Ligaments at the posterior superior iliac spine

In Causes of Back Dimples, it was determined that these 'Dimples of Venus' are created by

a short ligament stretching between the posterior superior iliac spine and the skin. They are thought to be genetic. (@Johnny)

The linked article in the answer to my original question says nothing more other than the fact that dimples of venus are normal dimples (not medically significant). states:

The sacroiliac joints move together as a single unit. From the back it is common to see a pair of dimples on the buttock near the base of the spine. These are sometimes called the “dimples of Venus” and they are a landmark for the top portion of the sacroiliac joints.

Posterior superior iliac spine (PSIS) marked in red

Image made by DBCLS (Polygondata is from BodyParts3D) CC BY-SA 2.1 jp, via Wikimedia Commons

Ligaments of the PSIS

Cooperstein & Hickey (2016) has an image of ligaments connected to the PSIS, but unless I am mistaken, the image doesn't seem to have the ligament(s) involved with the dimples of venus.

It seems from the description in Kumar, et al. (2014) that the "dimples of venus ligament(s)" are connected to the skin, and seeing that ligaments are fibrous connective tissues that normally connect bones to other bones, I am intrigued to know more. What is the name of these "dimple of venus ligaments" and what is their purpose?


Cooperstein, R., & Hickey, M. (2016). The reliability of palpating the posterior superior iliac spine: a systematic review. The Journal of the Canadian Chiropractic Association, 60(1), 36.
PMCID: PMC4807681

Kumar, A., Kanojia, R. K., & Saili, A. (2014). Skin dimples. International journal of dermatology, 53(7), 789-797. DOI: 10.1111/ijd.12376

It seems from the description in Kumar, et al. (2014) that the "dimples of venus ligament(s)" are connected to the skin, and seeing that ligaments are fibrous connective tissues that normally connect bones to other bones, I am intrigued to know more. What is the name of these "dimple of venus ligaments" and what is their purpose?

First, re: what a ligament is, you're correct in your understanding that ligaments generally bind bones to bones (vs. tendons), but the term is used more broadly as connective tissue that binds things together, holds them in place, is a remnant of a fetal structure, or a mesenteric fold. Your wikipedia link acknowledges this. Some examples are:

  • Round ligament of the liver: a remnant of fetal structure

  • Broad ligament of the uterus: a mesenteric fold

  • Median arcuate ligament: this one actually binds two muscles together
  • Sternopericardial ligament: binds the pericardium to the sternum

The unnamed short ligaments Kumar describes (and wikipedia, quora, and This Site have repeated), are probably unnamed because they are difficult to isolate and study, and they are not clinically relevant. They may even be theoretical. There are no studies on them indexed in medline, and they aren't discussed in any anatomy text I've read. Dimples are generally thought to be caused by fibrous connections between the skin and muscle, bone, or other deep tissue. If you ever cut into the back of a cadaver or surgical patient, you'll see that there are a great number of unnamed fibrous connections to the skin. It's not unreasonable for Kumar to invoke them as the cause for these dimples.

Sacroiliac Joint

The Sacroiliac joint (simply called the SI joint) is the joint connection between the spine and the pelvis.

  • Large diarthrodial joint [1] made up of the sacrum and the two innominates of the pelvis.
  • Each innominate is formed by the fusion of the three bones of the pelvis: the ilium, ischium, and pubic bone. [2]
  • The sacroiliac joints are essential for effective load transfer between the spine and the lower extremities.
  • It functions both as a shock absorber for the spine above and converts torque from the lower extremities into the rest of the body.
  • The sacrum, pelvis and spine-, are functionally interrelated through muscles, fascia and ligamentous interconnections.

Pelvic girdle

The pelvic girdle can be considered as the lower limb analogue to the pectoral girdle. It is responsible for attaching the lower limb to the axial skeleton. The pelvis itself is a paired composite structure made up by three bones (ilium, ischium and pubis) that articulates with the sacral part of the axial spine. The named ligaments of the pelvis mostly arise from the sacrum and attach to varying segments of the pelvic bone. There are others that span from the pelvis to the lumbar vertebrae, as well as to different points of the pelvis.

Iliolumbar ligament

The major ligament that runs from the pelvis to the sacrum is the iliolumbar ligament. Surprisingly, it starts out as a muscular structure during early childhood. It gradually becomes ligamentous and completes the transition around the fiftieth to sixtieth years of life. It is one of those ligaments that spans between the pelvis and vertebrae. The ligament is made up of two bands that originate from the transverse processes of L5. The superior band extends over the sacroiliac joint and across the iliac crest to blend with the thoracolumbar fascia. The inferior band also passes over the anterior sacroiliac ligament to insert in the posterior region of the iliac fossa.

Sacroiliac ligaments

There are three ligaments situated around the sacroiliac joint known as the anterior, interosseous and posterior sacroiliac ligaments.

  • Anterior Sacroiliac Ligament - It forms the anteroinferior component of the joint capsule. It courses from the pre-auricular surface of the ilium to the third segment of the sacrum. Note that the pre-auricular surface of the ilium is the area just anterior to the auricular surface, which is the area of articulation between the ilium and the sacrum.
  • Posterior Sacroiliac Ligament - This ligament covers the interosseous sacroiliac ligament as well as exiting dorsal rami of the sacral nerves. It forms the communication between the posterior superior iliac spine, as well as part of the iliac crest to the lateral and intermediate sacral crests.
  • Interosseous Sacroiliac Ligament - It fills the gaps between the ilium and sacrum at the posterosuperior aspect of the joint, deep to the posterior sacroiliac ligament.

Sacrospinous and sacrotuberous ligaments

The next two ligaments are particularly famous for transforming the lesser and greater sciatic notches into the lesser and greater sciatic foramina. These are the sacrospinous and sacrotuberous ligaments. The former is a thin, triangular, fibrous band that extends from the margins of the coccyx and sacrum to the spine of the ischium. It is often referred to as the degenerate component of the coccygeus muscle and it also travels anterior to the larger, more robust sacrotuberous ligament.

Sacrospinous ligament (dorsal view)

The latter ligament has several attachments to the posterior sacroiliac ligaments, lower transverse tubercles of the sacrum, the posterior superior iliac spine, the proximal part of the coccyx and the lower lateral margins of the sacrum. It then travels across the sciatic notch to complete its connection to the ischial tuberosity and continues along the ramus of the ischium as the falciform process. Of note, the falciform integrates with the fascia of the pudendal neurovascular structures. The sacrotuberous ligament also serves as a point of attachment for the most caudal fibers of gluteus maximus. Additionally, the most superficial fibers of this ligament integrate with the tendon of biceps femoris and continue with this structure to its insertion.

Sacrotuberous ligament (dorsal view)

Obturator membrane

Probably the most confined of all the ligaments of the pelvis is the obturator membrane. Although it is not officially called a ligament, it is fibrous in nature and spans the inner margin of the obturator foramen. It acts as a point of origin for both the obturator externus and obturator internus muscles.

Pubic ligaments

As previously stated, there are two sets of pelvic bones that form the pelvic cavity with the aid of the sacrum and coccyx posteriorly and the pubic symphysis anteriorly. The stability of the pubic symphysis is reinforced by the superior and inferior (arcuate) pubic ligaments. The superior pubic ligament extends laterally from one pubic tubercle to the other. On the inferior surface, the arc-shaped arcuate pubic ligament also crosses from one pubic ramus to the next. Generally, no movement occurs at this joint. However, women may experience dislocation at this point during childbirth.

Poupart's, Gimbernat's and Cooper's ligaments

Finally, there are three interrelated ligaments that are located within the inguinal ligament. Each is fundamental to the formation of a larger structure.

  • Inguinal ligament (of Poupart) - It courses from the anterior superior iliac spine to the ipsilateral pubic tubercle. This fibrous structure, which is a continuation of the aponeurosis of the external abdominal oblique muscle, goes on to form the floor of the inguinal canal.
  • Ligament of Gimbernat – More commonly known as the lacunar ligament, it is continuous with the inguinal ligament. It is a short fibrous band that spans the space between the inguinal and pectineal ligaments. The crescentic structure also forms the medial border of the femoral canal.
  • Pectineal ligament (of Cooper) - This ligament is a continuation of the lacunar ligament along the pectineal line of the pubic bone. It forms the posterior border of the femoral canal.

Just to summarise, the ligaments of the pelvis listed in a craniocaudal fashion are as follows:

  • Iliolumbar Ligament
  • Sacroiliac
    • Anterior
    • Interosseous
    • Posterior
    • Superior
    • Inferior

    Anesthesia Key

    Illustration of the posterior sacral ligaments: posterior superior iliac spine (1) iliolumbar ligament (2) interosseous and dorsal sacroiliac ligaments (3) sacrotuberous ligament (4) sacrospinous ligament (5). (Reprinted with permission from Dr. Danilo Janovic)

    Patient Selection

    The SIJ plays a causative role in up to 30% of patients with chronic low back pain. Afflicted patients will typically have back pain below the L5 level with radiation to the buttocks or lower extremities. Provocative physical exam tests can be used to identify likely candidates, and the findings of 3 or more positive tests have been found to have a modest predictive power (sensitivity 91%, specificity 78%) in relation to controlled comparative SIJ blocks. Key tests include distraction, compression, thigh thrust, Gaenslen’s, sacral thrust, and Patrick’s FABER. However, their ability to detect posterior complex pain has not been evaluated.

    Ultrasound Scanning

    Probe: C5-2 MHz curved transducer.

    Transverse Plane Scan

    Sonographic images of the posterior sacrum depicting the various views required for the performance of an ultrasound-guided sacral lateral branch block. The three injection points on the sacral lateral crest are marked by a star (★) probe placement on the skin surface is illustrated in the upper left inset of panel ( a ) scan lines are illustrated on a skeletal model in the left lower insets. ( a ) transverse sonographic view of the lower sacrum demonstrating the sacral cornu (SC) and posterior foramen of S4 (S4) ( b ) sacral cornu (SC), posterior foramen of S3 (S3), lateral sacral crest (LSC) ( c ) median sacral crest (MSC), lateral sacral crest (LSC), yellow star indicates injection target ( d ) median sacral crest (MSC), posterior foramen of S2 (S2), lateral sacral crest (LSC), black arrow indicates caudal aspect of sacroiliac joint ( e ) median sacral crest (MSC), lateral sacral crest (LSC), yellow star indicates injection target ( f ) median sacral crest (MSC), posterior foramen of S1 (S1), yellow star indicates injection target, posterior superior iliac spine (PSIS). (Reprinted with permission from Philip Peng Educational Series)

    Sagittal Plane Scan

    Parasagittal scan of the sacrum demonstrating the posterior sacral foramen. This view is used to confirm needle placement. Probe placement on the skin surface is illustrated in the upper left inset. The posterior foramen of S1, S2, and S3 are visible. (Reprinted with permission from Philip Peng Educational Series)

    Causes of Pelvic Fracture

    Low-energy pelvic fractures occur commonly in adolescents and the elderly.

    Adolescents typically present with avulsion fractures of the superior or inferior iliac spines or with avulsion fractures of the iliac apophyses or ischial tuberosity resulting from an athletic injury.

    Low-energy pelvic fractures in the elderly frequently result from falls while ambulating or insufficiency fractures, typically of the sacrum and anterior pelvic ring.

    High-energy pelvic fractures most commonly occur after motor vehicle crashes. Other mechanisms of high-energy pelvic fractures include motorcycle crashes, motor vehicles striking pedestrians, and falls.

    High-energy injuries that result in pelvic ring disruption are more likely to be accompanied by severe injuries to the central nervous system, abdomen, and chest. These are often the results of motor vehicle accidents.

    The Sacroiliac Joint

    At the completion of this chapter, the reader will be able to:

  • Describe the anatomy of the bones, the ligaments, the muscles, and the blood and nerve supply that comprises the sacroiliac (SI) region.
  • Describe the biomechanics of the sacroiliac joint (SIJ), including coupled movements, normal and abnormal joint barriers, kinesiology, and reactions to various stresses.
  • Perform a detailed objective examination of the SIJ, including palpation of the articular and the soft-tissue structures, specific passive mobility tests, passive articular mobility tests, and stability tests.
  • Evaluate the total examination data to establish the diagnosis.
  • Describe the intervention strategies based on clinical findings and established goals.
  • Design an intervention based on patient education, manual therapy, and therapeutic exercise.
  • Apply active and passive mobilization techniques, and combined movements to the SIJ, in any position using the correct grade, direction, and duration.
  • Describe the common pathologies and lesions of this region.
  • Evaluate intervention effectiveness in order to progress or modify an intervention.
  • Plan an effective home program and instruct the patient in this program.

    The sacroiliac joint (SIJ) serves as the supporting base of the spine and as the point of intersection between the spinal and the lower extremity joints. The SIJ is the least understood and, therefore, one of the most controversial and interesting areas of the spine. Determining a diagnosis in this region is complicated by the biomechanics of the SIJ and its relationships with the surrounding joints, including the hip, pubic symphysis, and lumbar spine.

    Grieve 1 has proposed that the SIJ, together with the other areas of the spine that serve as transitional areas, is of prime importance in understanding vertebral joint problems. This level of importance is perhaps surprising because isolated pelvic impairments are rare. However, findings for SIJ dysfunction appear to be common, and the literature is replete with intervention techniques aimed at correcting pelvic dysfunctions. 2–11 This may be explained by the fact that, in addition to being able to produce pain on its own, the SIJ often can refer pain. 12

    The level of interest surrounding this joint dates back to the Middle Ages, a time when the burning of witches was commonplace. It was noticed after these burnings that three of the bones were not destroyed: a large triangular bone and two very small bones. It can only be assumed that some degree of significance was given to the large triangular bone as it was deemed a sacred bone and was thus called the sacrum. It is unclear what significance was given to the two smaller bones, the sesamoid bones of the great toe.

    Despite these illustrious beginnings for the sacrum, it was not until approximately 100 years ago that significant attention was applied to the study of pelvic anatomy and function, and its relationship to low back and pelvic pain. At the start of the 20th century, SIJ strain was thought to be the most common cause of sciatica. 13 Then, in 1934, Mixter and Barr 14 reported that sciatica could be caused by a prolapsed intervertebral disk, and the interest in the SIJ as a source of sciatica dwindled. Since then, there have been periods when the joint has been blamed for almost all low back and leg pain, and times when it has only been considered a problem during pregnancy. It is now generally accepted that approximately 13% (95% CI: 9–26%) of patients with persistent low back pain have the origin of pain confirmed as the SIJ. 15


    Anatomically, the SIJ is a large diarthrodial joint that connects the spine with the pelvis ( Fig. 29-1 ) and which serves as a central base through which forces are transmitted both directly and indirectly. The structure of the pelvis and its surrounding tissues has evolved in conjunction with the evolutionary changes in human gait. Three bones comprise the SIJ: two innominates and the sacrum.

    FIGURE 29-1 The pelvis. (Reproduced, with permission, from Chapter 6. Headache & Facial Pain. In: Greenberg DA, Aminoff MJ, Simon RP. eds. Clinical Neurology , 8e. New York, NY: McGraw-Hill 2012.)


    The sacrum (Fig. 29-1), a strong and triangular bone located between the two innominates, provides stability to this area and transmits the weight of the body from the mobile vertebral column to the pelvic region. Evolutionary changes have resulted in an increased size of the sacrum to accommodate the increased osseous attachment of the gluteus maximus muscle, and to facilitate the increased compression produced in a bipedal stance. 11 The sacrum base is above and anterior, and its apex below and posterior (Fig. 29-1). This differs from nonhuman mammals in which the sacral base is horizontal, and the lumbar spine is kyphotic. 11 Five centra fuse to form the central part of the sacrum, which contains remnants of the intervertebral disks enclosed by bone. The sacrum has four pairs of pelvic sacral foramina for transmission of the anterior (ventral) primary rami of the sacral nerves and four pairs of posterior (dorsal) sacral foramina for transmission of the posterior (dorsal) primary rami.

    The transverse processes of the first sacral vertebra fuse with the costal elements to form the ala and the lateral crests (see Fig. 29-1). The ala of the sacrum forms the superolateral portions of the base. The superior articular processes of the sacrum (Fig. 29-1), which are concave and oriented posteromedially, extend upward from the base to articulate with the inferior articular processes of the fifth lumbar vertebra.

    On the posterior (dorsal) surface of the sacrum is a midline ridge of bone called the median sacral crest, which represents the fusion of the sacral spinous processes of S1 to S4. Projecting posteriorly from this crest are four spinous tubercles. The fused laminae of S1 to S5, which are located lateral to the median sacral crest, form the intermediate sacral crest.

    The sacral hiatus exhibits bilateral downward projections that are called the sacral cornua . These projections represent the inferior articular processes of the fifth sacral vertebra and are connected to the coccyx via the intercornual ligaments. On the inferolateral borders of the sacrum, approximately 2 cm to either side of the sacral hiatus, are the inferior lateral angles (ILAs). The triangular sacral canal houses the cauda equina. In addition to the more commonly considered bones and joints are those of the coccygeal spine. The coccyx, which is variable in size, consists of three to five vertebral units that are usually fused, with the exception of the first segment, which articulates with the distal end of the sacrum, and is referred to as the sacrococcygeal joint. 16 In general, the posterior (dorsal) surface of the coccyx is convex, so that its inferior aspect slopes anteriorly.


    The ilium, ischium, and pubic bone fuse at the acetabulum to form each innominate (Fig. 29-1). The ilium of each of the two innominates articulate with the sacrum, forming the SIJ, and the pubic bone of each of the innominates articulate with each other at the symphysis pubis. The ilia have undergone significant adaptations in response to bipedalism in such a way that the bone has twisted so that the lateral aspect is now directed anteriorly, and the gluteus medius and minimus muscles have migrated anteriorly with a resultant change in their function. 11

    Sacroiliac Joint

    The articulating surfaces of this joint differ, with the joint surface of the ilium formed from fibrocartilage and the sacral surface formed from hyaline cartilage. 17 The SIJ is in part synovial (25% of its surface) and in part syndesmosis, and so between the sacral and iliac auricular surfaces, the SIJ is deemed a synovial articulation or diarthrosis. 18,19

    The inverted, L-shaped, auricular articular surface of the sacrum (Fig. 29-1) is surrounded entirely by the costal elements of the first three sacral segments. The short (superior) arm of this L-shape lies in a craniocaudal plane, within the first sacral segment, and corresponds to the depth of the sacrum (see Fig. 29-1). It is widest superiorly and anteriorly. The long (inferior) arm of the L-shape lies in an anteroposterior (A-P) plane, within the second and third sacral segments, and represents the length of the sacrum from top to bottom. It is widest inferiorly and posteriorly. There are large irregularities on each articular surface 20 that are approximately, though not exactly, reciprocal, with the sacral contours being generally deeper. 21,22 In addition to the larger irregularities, there are smaller horizontal crests and hollows that run anteroposteriorly. The sacral articular surface is wedge shaped in its upper portion, formed by the first sacral segment and half of the second. Below this, the joint surfaces run nearly vertically and then diverge somewhat, making a flare which tends to prevent the sacrum from sliding upward between ilia. 22

    The morphology varies in size, shape, and contour from side to side, and between individuals and changes with aging. 23 In fact, variations in the SIJ morphology are so common that they have been classified as type A, being less vertical than type B, and type C as an asymmetric mixture of types A and B. 5 Each of these variants can alter the function of the pelvis and its influence on the lumbar lordosis. 24


    The configuration of the SIJ is extremely variable from person to person and between genders in terms of morphology and mobility. 22,25,26 However, it has been determined that these differences are not pathological, but normal adaptations. 25

    The articulating surfaces of the joint respond differently to the aging process, with early degenerative changes occurring on the iliac surface rather than on both surfaces of the joint simultaneously. 27 Other changes associated with aging include the development of intraarticular fibrous connections. 28 However, even with severe degenerative changes, the SIJ rarely fuses. 18

    The SIJ can be the site of manifestation for several disease processes, including SI tuberculosis, spondyloarthropathy (ankylosing spondylitis), and crystal and pyogenic arthropathies.

    Joint Capsule

    The SIJ capsule, consisting of two layers, is extensive and very strong. It attaches to both articular margins of the joint and is thickened inferiorly.


    Like other synovial joints, the SIJ is reinforced by ligaments, but the ligaments of the SIJ are some of the strongest and toughest ligaments of the body.

    Anterior Sacroiliac (Articular)

    The anterior sacral ligament ( Fig. 29-2 ) is an anteroinferior thickening of the fibrous capsule, which is relatively weak and thin compared to the rest of the SI ligaments. The ligament extends between the anterior and inferior borders of the iliac auricular surface and the anterior border of the sacral auricular surface. 18 The anterior sacral ligament is better developed near the arcuate line and the posterior-inferior iliac spine (PIIS), where it connects the third sacral segment to the lateral side of the preauricular sulcus.

    FIGURE 29-2 Anterior ligaments.

    Because of its thinness, this ligament is often injured and can be a source of pain. It can be palpated at Baer’s SI point* 29 and can be stressed using the anterior distraction and posterior compression pain provocation tests (see later).

    *Baer’s SI point has been described as being on a line from the umbilicus to the ASIS, 5 cm from the umbilicus.

    Interosseous Sacroiliac (Articular)

    This is a strong, short ligament located deep to the posterior (dorsal) SI ligament, and it forms the major connection between the sacrum and the innominate, filling the irregular space posterosuperior to the joint between the lateral sacral crest and the iliac tuberosity ( Fig. 29-3 ). 30 The deep portion sends fibers cranially and caudally from behind the auricular depressions. The superficial portion is a fibrous sheet connecting the superior (cranial) and posterior (dorsal) margins of the sacrum to the ilium, forming a layer that limits direct palpation of the SIJ. The interosseous SI ligament functions to resist anterior and inferior movement of the sacrum.

    FIGURE 29-3 Posterior ligaments.

    Posterior (Dorsal) Sacroiliac (Articular)

    The posterior (dorsal) SI ligament or long ligament (see Fig. 29-3), which is easily palpable in the area directly caudal to the posterior-superior iliac spine (PSIS), connects the PSIS (and a small part of the iliac crest) with the lateral crest of the third and fourth segments of the sacrum. 31 This is a very tough and strong ligament. The fibers of this ligament are multidirectional and blend laterally with the sacrotuberous ligament. It also has attachments medially to the erector spinae 32 and multifidus muscles 33 and the thoracodorsal fascia. Thus, contractions of the various muscles that attach to this ligament can result in the tightening of the ligament.

    Directly caudal to the PSIS, the ligament is so solid and stout that one can easily think a bony structure is being palpated. What complicates matters is the fact that the area overlying the ligament is a frequent source of pain. 34

    The lateral expansion of the long ligament in the region directly caudal to the PSIS varies between 15 and 30 mm. The length, measured between the PSIS and the third and fourth sacral segments, varies between 42 and 75 mm. The lateral part of the posterior (dorsal) ligament is continuous with fibers passing between ischial tuberosity and iliac bone.

    At the superior (cranial) aspect, the posterior (dorsal) ligament is attached to the PSIS and the adjacent part of the ilium, at the inferior (caudal) side to the lateral crest of the third and fourth, and occasionally to the fifth, sacral segments. 32

    Nutation (anterior motion) of the sacrum appears to slacken the posterior (dorsal) ligament, whereas counternutation (posterior motion) tautens the ligament. 32

    Sacrotuberous (Extraarticular)

    This ligament (see Fig. 29-3) is composed of three large fibrous bands, broadly attached by its base to the PSIS, the lateral sacrum, and partly blended with the posterior (dorsal) SI ligament. Its oblique, lateral fibers descend and attach to the medial margin of the ischial tuberosity, spanning the piriformis muscle from which it receives some fibers. The medial fibers, running anteroinferior and laterally, have an attachment to the transverse tubercles of S3, S4, and S5, and the lateral margin of the coccyx. To the posterior surface of the sacrotuberous ligament are attached the lowest fibers of the gluteus maximus and the piriformis, the contraction of which produces increased tension in the ligament. 35 Superficial fibers on the inferior aspect of the ligament can continue into the tendon of the biceps femoris.

    In addition to stabilizing against nutation of the sacrum, the sacrotuberous ligament also counteracts against the posterior (dorsal) and superior (cranial) migration of the sacral apex during weight bearing. 36,37

    Sacrospinous (Extraarticular)

    Thinner than the sacrotuberous ligament, this triangular-shaped ligament extends from the ischial spine to the lateral margins of the sacrum and coccyx, and also laterally to the spine of the ischium (see Fig. 29-3). The ligament runs anterior (deep) to the sacrotuberous ligament to which it blends and then attaches to the capsule of the SIJ. 33

    The sacrotuberous and sacrospinous ligaments, which convert the greater and lesser sciatic notches into the greater and lesser foramen respectively, oppose forward tilting of the sacrum on the innominates during weight bearing of the vertebral column.

    Iliolumbar (Indirect)

    The anatomy of the iliolumbar ligament (Fig. 29-2) is described in Chapter 28.

    Pubic Symphysis

    The pubic symphysis is classified as a symphysis because it has no synovial tissue or fluid, and it contains a fibrocartilaginous lamina or disk (Fig. 29-2). The bone surfaces of the joint are covered with hyaline cartilage but are kept apart by the presence of the disk.

    The following are the supporting ligaments of this joint 21 :

    Superior pubic ligament, a thick fibrous band.

    Inferior arcuate pubic ligament, which attaches to the inferior pubic rami bilaterally and blends with the articular disk.

    Posterior pubic ligament, a membranous structure that blends with the adjacent periosteum.

    Anterior ligament, a very thick band that contains both transverse and oblique fibers.

    The pubic symphysis is a common source of groin pain, particularly in athletes (see section “Groin Pain”).


    Lee 11 lists 35 muscles that attach directly to the sacrum or innominate, or both ( Table 29-1 ). A muscle attaching to bone has the potential for moving that bone, although the degree of potential varies. Rather than producing movement at the SIJ, the muscles around the pelvis are more likely involved directly or indirectly in helping to provide stability to the joint.

    Muscles That Attach to the Sacrum, Ilium, or Both

    Superficial transverse perineal ischiocavernosus


    This muscle (see Chapter 19) arises from the anterior aspect of the S2, S3, and S4 segments of the sacrum the capsule of the SIJ and the sacrotuberous ligament. It exits from the pelvis via the greater sciatic foramen, before attaching to the upper border of the greater trochanter of the femur.

    The piriformis primarily functions to produce external rotation and abduction of the femur, but is also thought to function as an internal rotator and abductor of the hip if the hip joint is flexed beyond 90 degrees. It also helps to stabilize the SIJ, although too much tension from it can restrict the motion of this joint. 38 The piriformis has been implicated as the source for a number of conditions in this area, including the following two

    Entrapment neuropathies of the sciatic nerve (piriformis syndrome. 39–45 ). Piriformis syndrome is described in Chapter 5.

    Trigger and tender points.

    Transversus Abdominis

    The transversus abdominis (TrA) is the deepest abdominal muscle and arises from the lateral one-third of the inguinal ligament, the anterior two-thirds of the inner lip of the iliac crest, the lateral raphe of the thoracolumbar fascia, and the inner surface of the lower six costal cartilages, interdigitating with the costal fibers of the diaphragm. 11 For a detailed description of the anatomy and function of the TrA, refer to Chapter 28. Although the TrA does not cross the SIJ directly, it can affect the stiffness of the pelvis through its direct anterior attachments to the ilium, as well as its attachments to the middle layer and the deep laminae of the posterior layer of the thoracodorsal fascia. 46,47


    The anatomy of the multifidus muscle is described in Chapter 28. Some of the deepest fibers of the multifidus attach to the capsules of the zygapophyseal joints 48 and are located close to the centers of rotation of spinal motion. They connect adjacent vertebrae at appropriate angles, and their geometry remains relatively constant through a range of postures, thereby enhancing spinal stability. 49

    Erector Spinae

    For a detailed description of the anatomy of the erector spinae, refer to Chapter 28. Through its extending effect on the spine and its substantial sacral attachments, the erector spinae might be thought to promote sacral nutation, although this has not been proven.

    Gluteus Maximus

    This is one of the strongest muscles in the body (see Chapter 19). It arises from the posterior gluteal line of the innominate, the posterior aspect of the lower lateral sacrum and coccyx, the aponeurosis of erector spinae muscle, the superficial laminae of the posterior thoracodorsal fascia, and the fascia covering the gluteus medius muscle, before attaching to the gluteal tuberosity. In the pelvis, the gluteus maximus blends with the ipsilateral multifidus, through the raphe of the thoracodorsal fascia, 33 and the contralateral latissimus dorsi, through the superficial laminae of the thoracodorsal fascia. 50 Some of its fibers attach to the sacrotuberous ligament. Tension in the sacrotuberous ligament increases when these fibers contract. 51


    This muscle arises from the iliac fossa (see Chapter 19), the iliac crest, the anterior SI ligament, the inferior fibers of the iliolumbar ligament, 52 and the lateral aspect of the sacrum. As it travels distally, its fibers merge with the lateral aspect of the psoas major tendon to form the iliopsoas, which continues onto the lesser trochanter of the femur, sending some fibers to the hip joint capsule as it passes.

    Long Head of the Biceps Femoris

    The long head of the biceps femoris originates from the ischial tuberosity and sacrotuberous ligament. In addition to functioning as a hip extensor and knee flexor (see Chapter 19, the long head of the biceps femoris, due to its connections to the sacrotuberous ligament, may also have a proprioceptive role during activities such as gait.

    Pelvic Floor Musculature

    The term “pelvic floor muscles” primarily refers to the levator ani, a muscle group composed of the pubococcygeus, puborectalis, and iliococcygeus. The levator ani muscles join the coccygeus muscles to complete the pelvic floor. The pelvic floor muscles work in a coordinated manner to increase intraabdominal pressure, provide rectal support during defecation, inhibit bladder activity, help support the pelvic organs, and assist in lumbopelvic stability. 53

    Levator Ani. The levator ani ( Fig. 29-4 ) originates anteriorly from the pelvic surface of the pubis, posteriorly from the inner surface of the ischial spine, and from the obturator fascia. It inserts into the front and sides of the coccyx, to the sides of the rectum, and into the perineal body. The levator ani forms the floor of the pelvic cavity, functions to constrict the lower end of the rectum and vagina, and can also be activated during forced expiration.

    FIGURE 29-4 Pelvic floor muscles. (Reproduced, with permission, from Chapter 12. Pelvis and Perineum. In: Morton DA, Foreman K, Albertine KH. eds. The Big Picture: Gross Anatomy . New York, NY: McGraw-Hill 2011.)

    The muscle, which consists of anterior, intermediate, and posterior fibers, is innervated by the muscular branches of the pudendal plexus.

    Anterior Fibers. The anterior fibers insert into the perineal body, comprise the levator prostatae or sphincter vaginae, and form a sling around the prostate or vagina.

    Intermediate Fibers

    Puborectalis. The puborectalis (see Fig. 29-4) originates at the pubis and forms a sling around the junction of the rectum and the anal canal. The muscle pulls the anorectal junction anteriorly, assisting the external sphincter in anal closure.

    Pubococcygeus. The pubococcygeal muscle (see Fig. 29-4) arises from the pubis and its superior ramus and passes posteriorly to insert into the anococcygeal body between the coccyx and the anal canal. The muscle functions to pull the coccyx forward. It also serves to elevate the pelvic organs and compress the rectum and vagina.

    Posterior Fibers. The iliococcygeal muscle (see Fig. 29-4) arises from the arcus tendineus and ischial spine and inserts onto the last segment of the coccyx and the anococcygeal body. The muscle functions to pull the coccyx from side to side and to elevate the rectum.

    Levator Plate. The pubococcygeal muscle and the iliococcygeal muscle unite posterior to the anorectal junction to form the levator plate, which inserts into the coccyx.

    Coccygeus. This muscle (Fig. 29-4) arises from the pelvic surface of the ischial spine and sacrospinous ligament and inserts on the coccyx margin and side of the lowest segment of the sacrum. Supplied by the muscular branches of the pudendal plexus, the coccygeus functions to pull forward and support the coccyx. In addition, the coccygeus muscle provides support for the pelvic contents and the SIJ.


    It remains unclear precisely how the anterior and posterior aspects of the SIJ in humans are innervated, although the anterior portion of the joint likely receives innervation from the posterior rami of the L2 to S2 roots. 54 Contribution from these root levels is highly variable and may differ among the joints of given individuals. 55 Additional innervation to the anterior joint may arise directly from the obturator nerve, superior gluteal nerve, or lumbosacral trunk. 22,56 The posterior portion of the joint is likely innervated by the posterior rami of L3 to S3, with a particular contribution from S1 and S2. 57 An additional autonomic component of the joint’s innervation further increases the complexity of its neural supply and likely adds to the variability of pain referral patterns from this area. 56,58

    The current reference standard for confirming pain stemming from the SIJ is fluoroscopically guided, contrast-enhanced, intraarticular anesthetic blocks. 59 Using this method, the SIJ has been identified in 10% to 27% of patients with low back pain as a source of their primary pain. 15,60,61 Mechanical pain resulting from SIJ dysfunction may manifest as sacral pain but may also refer pain distally. For example, SIJ problems can refer pain to the iliac fossa, the buttock, the groin, the superior lateral and posterior thigh, and rarely below the knee. 62 In general, SIJ pain is characterized by unilateral pain below the level of L5, in the absence of midline pain, whereas irritation of a spinal nerve may cause radicular symptoms below the knee. 63 Pubic symphysis dysfunction typically results in localized pain, or groin pain, which is aggravated by activities involving the hip adductor or rectus abdominis muscles. 64 However, studies have shown that using evidence of pain referral patterns, or evidence of groin pain is neither sensitive nor specific for SIJ dysfunction. 65

    Pain also may be referred to the sacrum from a distant structure, including the contralateral sacrospinalis muscle, 66 the ipsilateral interspinous ligaments of L3 to S2, 67 and the L4 to L5 facet joints. 68 In addition, it is well established that dysfunctional pelvic floor muscles can contribute to the symptoms of interstitial cystitis and the so-called urethral syndrome, which is urgency frequency with or without chronic pelvic pain. 69–71


    Motions at the neighboring lumbar spine predominantly occur around the sagittal plane and comprise flexion and extension, whereas the motions occurring at the hip occur in three planes and include the one motion that the lumbar spine does not tolerate well, that is, rotation. Thus, the pelvic area must function to transfer the loads generated by body weight and gravity during standing, walking, sitting, and other functional tasks. 72 To date, there is very little agreement, either among or even within disciplines, about how the structures of the pelvis achieve this. For many decades, it was thought that the SIJ was immobile due to the close fitting nature of the articular surfaces. Research has now shown that mobility of the SIJ is not only possible, 73–76 but also essential for shock absorption during weight-bearing activities. 77 However, the range of motion (ROM) in the SIJ is small, less than 4 degrees of rotation and up to 1.6 mm of translation. 74,78 Of interest, is the fact that one study 79 found no difference in available ROM between the symptomatic and asymptomatic sides.

    It is likely that the movement of the pelvis is in the nature of deformations and slight gliding motions around a number of undefined axes, with the joints of the pelvic ring deforming in response to body weight and ground reaction forces. The amplitude of this motion likely varies among individuals. Motion at the SIJ is facilitated by several features, including the following:

    The fibrocartilaginous surfaces of the innominate facets, which are deformable, especially during weight bearing, when the surfaces are forced together.

    The pubic symphysis—if the innominates are moving at the SIJ, then they must also be moving at their anterior junction, which would allow for an immediate, and almost perfect, reciprocal motion.

    No manual diagnostic tests have shown reliability for determining how much an individual’s SIJ is moving in either symptomatic or asymptomatic subjects. In contrast to Sturesson’s study, 78 when Doppler imaging testing has been used to measure stiffness (or laxity) of the SIJ in subjects with and without pelvic pain, it has been shown that asymmetry of stiffness between sides correlated with the symptomatic individual. 80–82 These studies have shown that within the same subject, asymptomatic individuals have similar values for the left and right SIJs, whereas individuals with unilateral posterior pelvic girdle pain had different stiffness values for the left and right sides. Theoretically, when assessing SIJ mobility, a dysfunction at the SIJ can manifest as one of the two types of asymmetries

    If one of the SIJs is hypermobile, the amplitude of motion is increased asymmetrically, and the resistance to motion is decreased on the dysfunctional side.

    If one of the SIJs is hypomobile, the amplitude of motion is asymmetrically reduced, and the resistance to motion is increased on the dysfunctional side.

    Thus, the current trend is to focus more on the symmetry, or asymmetry, of the motions palpated or observed.

    Anatomical research, 83–85 initiated to determine the source of low back pain, has demonstrated that alterations in the pattern of muscular contraction and the timing of specific muscle activation differ between healthy subjects and those demonstrating symptoms. Furthermore, studies 86 have shown that the strength and endurance of the trunk muscles are important in determining the muscle capacity of individuals. This research has led to theories about the force- and form-closure mechanisms of joints and how stability is necessary at joints for effective load transfer. Based on this knowledge, functional tests of load transfer through the pelvic girdle have been developed 87–89 together with a number of treatment protocols. 90–92 This approach has three physical components (form closure, force closure, and motor control) and one psychological component (emotions).

    In upright positions, the SIJ is subjected to considerable shear force as the mass of the upper body must be transferred to the lower limbs via the ilia. 93,94 The body has two mechanisms to overcome this shear force: one dependent on the shape and structure of the joint surfaces of the SIJs (form closure), which is wedge shaped with a high coefficient of friction, and the other mechanism involving generation of compressive forces across the SIJ via muscle contraction (force closure). 94

    Form Closure

    Form closure refers to a state of stability within the pelvic mechanism, with the degree of stability dependent on its anatomy, with no need for extra forces to maintain the stable state of the system. 85 The following anatomic structures are proposed to assist with form closure:

    The congruity of the articular surfaces and the friction coefficient of the articular cartilage. Both the coarseness of the cartilage and the complementary grooves and ridges increase the friction coefficient and thus contribute to form closure by resisting against horizontal and vertical translations. 22 In infants, the joint surfaces are very planar, but between the ages of 11 and 15 years, the characteristic ridges and humps that make up the mature sacrum begin to form. By the third decade, the superficial layers of the fibrocartilage are fibrillated, and crevice formation and erosion has begun. By the fourth and fifth decades, the articular surfaces increase irregularity and coarseness and the wedging is complete. 18

    The integrity of the ligaments.

    The shape of the closely fitting joint surfaces.

    According to current research, when the sacrum nutates, or flexes, relative to the innominate ( Fig. 29-5 ), or when the innominate posteriorly rotates relative to the sacrum, the greatest number of ligaments, particularly the interosseous and posterior (dorsal) ligaments, are tightened at the SIJ. 85,95,96 These latter ligaments lie posterior to the joint and approximate the posterior iliac bones when placed under tension. 95 Thus, nutation of the sacrum can be described as the close packed position, or self-locking mechanism, for the SIJ and is, therefore, the most effective position for transferring high loads. This position somewhat conveniently produces a position of lumbar lordosis, which is advocated in many interventions for the lumbar spine.

    FIGURE 29-5 Sacral nutation.

    Just as nutation of the sacrum enhances the self-locking mechanism, counternutation of the sacrum ( Fig. 29-6 ), which occurs during activities, such as the end range of forward bending, sacral sitting, long sitting, and hip hyperextension, reduces the self-locking mechanism. 95 . This position results in a loss of the lumbar lordosis and an increase in intervertebral disk pressure (see Chapter 28).

    FIGURE 29-6 Sacral counternutation.

    Using forward bending at the waist as an example, a combination of anterior and outward rotation of both innominates results in the approximation and superior motion of both PSISs, while the sacrum nutates ( Table 29-2 ). After approximately 60 degrees of forward bending, the innominates continue to rotate anteriorly, but the sacrum no longer nutates. 84 If the sacrum remains nutated throughout the forward bending, the SIJ remains compressed and stable. However, if the sacrum is forced to counternutate earlier in the range, as in individuals with tight hamstrings, less compression occurs, thereby increasing the reliance on dynamic stabilization provided by muscles and thus making the SIJ more vulnerable to injury. 84

    Lumbar Motions and Sacroiliac Motions

    Nutation, then counternutation

    Slight posterior rotation

    Ipsilateral: Posterior rotation

    Contralateral: Anterior rotation

    Ipsilateral: Anterior rotation

    Contralateral: Posterior rotation

    Ipsilateral: Side bends ipsilaterally

    Contralateral: Side bends contralaterally

    Force Closure

    Force closure requires intrinsic and extrinsic forces to keep the SIJ stable. 85 These dynamic forces involve the neurological and myofascial systems and gravity. Together, these components produce a self-locking mechanism for the SIJ. Optimum force closure requires the application of just the right amount of force at just the right time, which in turn requires a motor control system that can predict the timing of the load and prepare the system appropriately. The degree of force closure depends on the capability of an individual’s form closure and the various loading conditions (e.g., speed, duration, magnitude, and predictability). 97

    In a kinetic analysis of the pelvic girdle, Vleeming et al. 50,95 identified a number of muscles that resist translational forces and which are specifically important to the force-closure mechanism: the erector spinae, gluteus maximus, latissimus dorsi, and biceps femoris (see Chapter 28). Two other muscle groups, an “inner muscle unit” and an “outer muscle unit” also play an important role. 84,86,92 The inner muscle unit consists of the following:

    Transversus abdominis (TrA). A study by Richardson et al. 98 found that contraction of the TrA significantly decreases the laxity of the SIJ, and that this decrease in laxity is larger than that caused by a bracing action using all the lateral abdominal muscles. Theoretically, contraction of the TrA produces a force that approximates the ilia anteriorly. 98

    The muscles of the pelvic floor. Hemborg et al. 99 have demonstrated that the pelvic floor muscles coactivate with the TrA during lifting tasks.

    Multifidus. Studies 100–102 have reported that the deep fibers of the multifidus become inhibited and reduced in size in individuals with low back and pelvic girdle pain.

    The outer muscle unit consists of four systems: the posterior oblique system (latissimus dorsi, gluteus maximus, and thoracolumbar fascia), the deep longitudinal system (erector spinae, deep lamina of the thoracolumbar fascia, sacrotuberous ligament, and biceps femoris), the anterior oblique system (external and internal oblique, contralateral adductors of the thigh, and the intervening anterior abdominal fascia), and the lateral system (gluteus medius–minimus and contralateral adductors of the thigh). The outer muscle unit is proposed to contribute to the force-closure mechanism in the following manner 84 :

    Posterior oblique system. The gluteus maximus (see Chapter 19), which blends with the thoracodorsal fascia, and the contralateral latissimus dorsi contribute to force closure of the SIJ posteriorly by approximating the posterior aspects of the innominates. This oblique system is a significant contributor to load transference through the pelvic girdle during the rotational activities of gait.

    Deep longitudinal system. This system serves to counteract any anterior shear or sacral nutation forces as well as to facilitate compression through the SIJs. As mentioned in the anatomy section, the long head of the biceps femoris muscle controls the degree of nutation via its connections to the sacrotuberous ligaments. 36

    Anterior oblique system. The oblique abdominals, acting as phasic muscles, initiate movements. 92 and are involved in all movements of the trunk and upper and lower extremities, except when the legs are crossed. 103

    Lateral system. The lateral system functions to stabilize the pelvic girdle on the femoral head during gait through a coordinated action.


    The stability of the SIJ is a factor of the length and strength of the muscle units, neuromuscular control, and the ability of the sacrum to nutate in all positions of threat. Weakness or insufficient recruitment and/or unbalanced muscle function within the lumbar/pelvic/hip region can reduce the force-closure mechanism, which can result in compensatory movement strategies. 104 These compensatory movement strategies and/or patterns of muscle imbalance may produce a sustained counternutation of the sacrum, thereby “unlocking” the mechanism and rendering the SIJ vulnerable to injury. This unlocked position of the pelvis may also increase shear forces at the lumbar spine and abnormal loading of the lumbar disks.

    The sacrococcygeal joint has a limited amount of movement in flexion and extension, ranging from approximately 5–15 degrees in either direction. 105 A posterior rotation (flexion) motion occurs when moving from a standing to a sitting position, which is thought to enable optimal force absorption in the seated position. 16 The reverse occurs when moving from a seated to a standing position.

    As alluded to earlier, the sacral positions that correspond to poor sacral biomechanics are very similar to those lumbar spine positions that are unfavorable to spinal stability. Conversely, the positions that enhance sacral stability also enhance lumbar spine stability. As a result, there has been much confusion amongst disciplines when determining whether the SIJ or lumbar spine is the cause of the patient’s symptoms. For example, consider the prone on elbows position (see Chapter 28), which nutates the sacrum and increases the lordosis of the lumbar spine. If a patient with either a sacral dysfunction or an intervertebral disk herniation is asked to adopt this position, the symptoms would likely decrease.


    Most investigators agree that no single test can be used to confirm the diagnosis of SIJ dysfunction because of the complexity of the anatomy and biomechanics and its proximity to other symptom-provoking structures.

    Diagnostic physical examination tests that are commonly used to determine a diagnosis include 55

    direct tenderness

    soft-tissue examination for zones of hyperirritability and tissue texture changes

    evaluation of referral zones

    associated fascial or musculotendinous restrictions

    abnormal regional length–strength muscle relationships

    postural analysis

    true leg length and functional leg-length determination

    static and dynamic osseous landmark examinations and

    provocative testing including traditional orthopaedic tests, motion demand tests, and ligament tension tests.

    Although traditionally assumed to be reliable and diagnostically useful, none of these tests has ever been validated against an independent criterion standard. 55 As a consequence, controversy exists about which group of tests is the best.

    Under the premise that a relationship exists between pelvic asymmetry and low back pain, orthopaedic, osteopathic, and physical therapy tests promote the use of pain provocation (symptom based) tests and static (positional) or dynamic (motion or functional) tests. 1,10,38,84,106–109

    The use of static tests has been questioned, 110–114 as, although Cibulka et al. 115 found the results from these tests reliable, Levangie 114 found a weak association between standing PSIS asymmetry and low back pain, at least in selected groups. The problems with static testing are

    the high degree of anatomical variability in this area

    determining whether the asymmetry noted is normal or abnormal

    determining which side is abnormal and

    determining whether the asymmetry is too asymmetric or not asymmetric enough. For example, if the right innominate is anteriorly rotated, compared with the left, is it rotated too much, too little, or just the right amount compared with its starting position? Because the starting position is not known, the degree of rotation cannot be assessed.

    The dynamic tests do not fare much better. Dreyfuss et al. 55 reported 20% positive findings in one or more of the dynamic (motion or functional) tests in a group of asymptomatic people. The major problem with the dynamic tests is that SIJ motion is small, so it is highly implausible to be able to detect it. An example of a dynamic test is the standing flexion test, which has frequently been used to analyze SIJ mobility and to determine the side of the impairment. The test is performed as follows: Each PSIS is palpated with the thumb placed under it caudally. The patient then bends forward at the waist. Provided there is no impairment in the SIJ or the lower lumbar spine, as the patient bends forward, both thumbs should move superiorly (cranially). If one SIJ joint is “blocked,” it moves upward further in relation to the other side. 113 Thus far, reliability studies of the standing flexion test show that it lacks sufficient diagnostic power. 113,116,117 This shortfall may be because the compression of the joints caused by the sacral nutation in the early to midranges of forward flexion likely limits movement of the SIJ. 118

    Some studies have reported that pain provocation tests have a good interexaminer reliability, 113,119 but they have not been found reliable by others. 15,116 This is likely because the pain provocation tests have only been found reliable in identifying SIJ dysfunction in certain populations, such as patients with posterior pelvic pain during or following pregnancy. 120 Laslett et al. 121 reported that adequate sensitivity (0.88) and specificity (0.78) can be achieved using a clinical prediction rule involving two positive tests of distraction, thigh thrust, compression, and sacral thrust (see Pain Provocation Tests in Special Tests section). The diagnostic process begins with the two tests that have the highest positive predictive value and specificity (distraction test) and negative predictive value and sensitivity (thigh thrust) for identifying SIJ pathology. If these two tests both recreate the patient’s SIJ pain (positive), further tests are not indicated. If one or neither of the two tests are positive, the clinician follows the algorithm in Figure 29-7 .

    FIGURE 29-7 Decision-making algorithm for the SIJ.

    As several recent studies have found improved interrater reliability in the diagnosis of low back pain when using a combination of physical examination procedures as opposed to a single model approach, 15,55,113,122,123 it would be logical to assume that a similar approach would work with the SIJ.

    Ideally, the diagnosis needs to be based on the results of a thorough biomechanical examination that includes an assessment of load transfer, and pain provocation. Patients with failed load transfer through the pelvic girdle often present with inappropriate force closure, in that certain muscles become overactive while others remain inactive, delayed, or asymmetrical in their recruitment. 124 When approaching SIJ dysfunction it is likely more important to determine why there are symptoms, rather than attempting to identify the specific symptom generating structures.


    The main objective of SIJ assessment is to determine whether the condition appears to primarily involve 97

    too much compression occurring from stiff, fibrosed joints or hypertonicity of the global muscles system

    poor control of loose joints or under-activation of the deep (local) stabilizing muscles system and

    a combination of too much compression and too little control throughout the lumbopelvic–hip complex.

    In most cases, an examination of the pelvic joints is of little use if the lumbar spine and the hip joints have not been previously cleared by examination or intervention, because both of these joints can refer pain to this area and may also profoundly affect the function of the SIJ.


    A history of low back pain or leg pain, or both, warrants an examination of the lumbopelvic–hip complex. The most common presenting symptoms in patients with SIJ dysfunction are complaints of pain or tenderness over the region of the PSIS. 125–127 The clinician must also determine whether the current problem is a consequence of pregnancy and/or delivery. If so, it is important to ascertain when the symptoms began, what was the nature of the delivery, and how much trauma occurred to the pelvic floor and the abdominal wall. 128

    The following findings are likely to be present with an SIJ dysfunction: 12,55,129,130

    A history of sharp pain that occurred with a particular activity and that awakens the patient from sleep upon turning in bed. The clinician must ask what kind of bed the patient sleeps in, and what position is most frequently adopted.

    Pain with running, walking, ascending or descending stairs, or hopping or standing on the involved leg.

    Pain with forward bending of the trunk and pain with standing hip flexion.

    Pain with transitional movements such as rising to stand from a sitting position or getting in and out of the car.

    Pain with a straight-leg raise at, or near, the end of the range (occasionally early in the range when hyperacute).

    Pain and sometimes limitation on extension and ipsilateral side bending of the trunk.

    Pain that is worsened with long periods of sitting or standing if the lumbar lordosis is not maintained.

    The clinician must determine the exact location of the pain/dysesthesia and whether it is localized or diffuse, and its quality (see Chapter 4). If the symptoms do radiate, the clinician must determine how far down the limb or limbs the symptoms are felt, or whether the symptoms radiate into the abdomen or thorax. 128

    Finally, the clinician should ask the patient if there have been any adjunctive diagnostic tests (i.e., x-ray, computed tomography, or magnetic resonance imaging), or any laboratory tests.

    Systems Review

    Given the number of visceral organs in the vicinity of the SIJ, the clinician must complete a thorough systems review to rule out a visceral source for the symptoms. A Cyriax scanning examination (see Chapter 4) should be performed on any patient who presents with an insidious onset of pelvic pain. The scanning examination, which includes the primary stress tests (anterior and posterior distraction), can be used to help detect sacroiliitis resulting from microtraumatic arthritis, macrotraumatic arthritis, or systemic arthritis (e.g., ankylosing spondylitis, Reiter’s syndrome), or the more serious pathologies grouped under the sign of the buttock (see Chapter 19). Primary breast, lung, and prostate cancers are among the most common cancers to metastasize to the axial skeleton, including the pelvic ring. 131 A further source of sacral pain can be a stress fracture of the sacrum, which can be associated with a wide range of extrinsic and intrinsic risk factors (see “Intervention Strategies”), and an equally wide range of symptoms and signs. 132

    Tests and Measures

    As previously mentioned, in order to rule in or rule out SIJ dysfunction, a thorough musculoskeletal examination of the low back, the pelvis, the hips, and the remainder of the lower extremities, including a full neurologic evaluation must be performed.


    The observation should begin as the patient enters the treatment area to assess the impact the patient’s condition has on gait. As described in chapter 6, there should be minimal deviation of the head in either plane and no deviation of the pelvis in the coronal plane relative to the lumbar spine and hip (Trendelenburg sign). Asymmetry in stride length and time spent in each phase of the gait cycle can be indicative of impairments within the lumbopelvic hip complex. 128 In addition, an avoidance of the normal heel impact at initial contact may indicate an attempt by the patient to reduce the ground reaction forces and resultant joint loading.

    Observation should also include an overall assessment of posture to check for the presence of asymmetry (see Chapter 6). The primary spinal curves should be maintained (i.e., gentle even lumbar lordosis, thoracic kyphosis, and cervical lordosis), and there should be no kinks, shifts, hinges, or transverse plane rotations in the entire spinal curve. 128 The clinician should observe the degree of tilt at the pelvis. The question of cause and effect should be raised. An anterior pelvic tilt, which occurs when the anterior-superior iliac spine (ASIS) moves anteriorly and inferiorly, causes hip flexion and an increase in the lumbar lordosis (extension) and thoracic kyphosis. The anterior pelvic tilt results in a stretching of the abdominals and the sacrotuberous, SI, and sacrospinous ligaments, and an adaptive shortening of the hip flexors, the hamstrings, and the erector spinae. In contrast, a posterior pelvic tilt, which occurs when the PSIS moves posteriorly and inferiorly, results in lengthening of the hip flexors, the hamstrings, and the erector spinae, and adaptive shortening of the abdominals and the gluteals.

    A lateral pelvic tilt results in opposite motions at each side of the pelvis. The pelvic motion is defined by what is occurring at the iliac crest of the pelvis that is opposite the weight-bearing extremity/side of the pelvis that is moving. A lateral pelvic tilt may be caused by scoliosis with ipsilateral lumbar convexity, a leg-length discrepancy, or shortening of the contralateral quadratus lumborum. This position results in adaptive shortening of the ipsilateral hip abductors and contralateral hip adductors, and weakness of the contralateral hip abductors. A lateral pelvic tilt is not the same as a pelvic shift. A pelvic shift results in extension of the hip and extension of the lower lumbar spinal segments and is often seen with slouched or relaxed postures.

    There appears to be a strong correlation between the position of the pelvis and the forward head. 133 If the pelvic landmarks are asymmetric, and the patient has a forward head, the clinician should attempt to correct the forward head. If the attempted correction of the forward head worsens the pelvic asymmetry and increases the symptoms, the intervention should be aimed at correcting the asymmetry. If the attempted correction of the forward head improves the pelvic asymmetry and the symptoms, the subsequent intervention should be aimed at correcting the forward head. 134


    The pelvic crossed syndrome (see Chapter 28) produces an increase in anterior tilt accompanied by an increase in lumbar lordosis.

    Hip Range of Motion

    The ROM of the hip, including internal and external rotation, is performed to help rule out pain referred from the hip joint. Although a unilateral limitation of hip motion, in which one of the motions is unequal between the left and right sides, has been observed in patients with disorders of the SIJ, 76,135–137 the evidence to demonstrate whether hip motion is limited in patients with signs of SIJ dysfunction is inconclusive. LaBan et al. 64 noted asymmetry in hip abduction and external rotation in patients with inflammation of the SIJs. Dunn et al. 138 reported limited hip mobility in patients with infection of the SIJ however, no mention was made as to which movements were limited.

    Others have described cases in which patients with low back pain had unilateral, limited internal hip rotation and excessive external hip rotation, and also exhibited signs of SIJ dysfunction. A recent study by Cibulka et al. 135 attempted to determine whether a characteristic pattern of hip ROM existed in patients with low back pain, and whether those classified as having SIJ dysfunction have a different pattern of hip ROM compared with those with unspecified low back pain. The study found that patients with low back pain, who had signs suggesting SIJ regional pain, had significantly more hip external than internal rotation ROM on one side. The authors concluded that identifying unilateral hip ROM asymmetry in patients with low back pain might help in diagnosing SIJ regional pain. 135 Hip ROM and its relation to lumbar and pelvic motion can be assessed using the one-leg stand test, also known as the stork test or Gillet test.

    One-Leg Stand Test. The patient is positioned in standing and is then asked to stand on one leg, and to flex the contralateral hip and knee towards the waist. The clinician observes the effort required and the ability to perform the task. The pelvis should not anteriorly/posteriorly/laterally tilt, nor rotate in the transverse plane as the weight is shifted to the supporting limb. 128 The test is then repeated on the opposite side. Once the patient has performed this maneuver several times, the clinician kneels behind the patient and, using the thumb of one hand, palpates the PSIS, and the thumb of the other hand to palpate the sacrum at either S2 or the ipsilateral ILA. The patient is asked to repeat the test while the clinician palpates. A small amount of posterior rotation of the innominate during this maneuver should be felt, and the quality and amplitude should be symmetrical between left and right sides. 128

    Lumbopelvic Range of Motion

    Forward Bending. The patient is positioned in standing and is asked to bend forward at the waist while the clinician observes and palpates. Forward bending at the waist results in a posterior displacement of the pelvic girdle which, in turn, shifts the center of gravity (COG) behind the pedal base such that slight plantar flexion of the talocrural joint occurs. 139 When the leg lengths are equal, the sacrum should nutate bilaterally and symmetrically relative to the innominates and remain nutated throughout the forward bending motion as the pelvic girdle flexes at the hip joints. 118 The innominate should remain posteriorly rotated relative to the sacrum throughout the forward bend. When the pelvis unlocks, the innominate can be felt to rotate anteriorly relative to the ipsilateral sacrum. 87,140 There should be a symmetry of the paravertebral fullness between the thorax and the pelvic girdle so that it is equal on both sides of the spinal column. As the patient returns to the standing position, the sacrum should remain symmetrically nutated until the erect posture is reached. There is no relative anterior or posterior rotation between the innominates during forward bending, but both should travel an equal distance as the pelvic girdle anteriorly tilts. 139 The forward bending should be repeated several times to note the consistency/inconsistency of any positive findings and the ease with which the patient is able to bend forward repeatedly. 128 A positive test for inadequate load transfer is if there is a lack of anterior pelvic tilt, excessive flexion of the thoracolumbar spine, and any twisting that occurs in the pelvic girdle. 97 Although asymmetry of motion of the innominate during forward bending is a positive finding, it is not indicative of any specific dysfunction of the SIJ.

    Backward Bending. The patient is positioned in standing and is asked to bend backward at the waist while the clinician observes and palpates. Backward bending at the waist results in an anterior displacement of the pelvic girdle which, in turn, shifts the COG in front of the pedal base such that slight dorsiflexion of the talocrural joint occurs. 139 When the leg lengths are equal, the sacrum should counternutate bilaterally and symmetrically relative to the innominates and remain counternutated throughout the backward bending motion as the pelvic girdle extends symmetrically at the hip joints. 118 The lumbar spinal segments should extend symmetrically without shifting or hinging, and the innominate should remain posteriorly rotated relative to the sacrum as the pelvic girdle tilts posteriorly throughout the backward bend. As the pelvis unlocks, the innominate can be felt to rotate anteriorly relative to the ipsilateral sacrum. Even though the pelvic girdle is tilting posteriorly, it is the relative motion between the innominate and the sacrum that is important to assess. 128 As the patient returns to the standing position, the sacrum should remain symmetrically counternutated until the erect posture is reached. There is no relative anterior or posterior rotation between the innominates during forward bending, but both should travel an equal distance as the pelvic girdle posteriorly tilts. 139 The backward bending should be repeated several times to note the consistency/inconsistency of any positive findings and the ease with which the patient is able to bend backwards repeatedly. 128 A positive test for inadequate load transfer is if there is a lack of posterior pelvic tilt, excessive extension of the thoracolumbar spine, and any twisting that occurs in the pelvic girdle. 97

    Side Bending. The patient is positioned in standing and is asked to side bend to the right and then to sidebend to the left while the clinician observes and palpates. Right side bending of the body is initiated by displacing the upper legs/pelvis to the left so that the right femur abducts and the left femur adducts, thus maintaining the COG within the pedal base. 139 The apex of this lateral bending curve should be at the level of the greater trochanter, and the body should remain in the coronal plane. The lumbar spinal segments should sidebend symmetrically without shifting or kinking. At the pelvis, during side bending, the left innominate posteriorly rotates relative to the right innominate, and the sacrum rotates to the left while the lumbar spine side bends to the right. 139 The reader should be able to extrapolate what happens during left side bending.

    Landmark Palpation

    The palpation of landmarks can be used to locate areas of tenderness rather than for detecting pelvic asymmetry, because as asymmetry of pelvic landmarks is the norm, “positive” findings are likely to be misleading. 114 The various landmarks of the pelvis are palpated with the patient positioned standing, sitting, and lying (see Figs. 29-8 and 29-9 ).

    Results The authors concluded “These results support for the first time the validity of clinical assumptions about disc behavior in functional positions: sitting postures may increase risk of posterior derangement, and prone and supine may be therapeutic for symptoms caused by posterior disc displacement.” These results confirmed the views of JH Cyriax which he had published as far back as 1945 2 and subsequently by others 3, ,4,5,6 . It also validates the 2Tilt concept as the most effective, possibly the only, way to ensure ‘Safe Sitting’.

    />The relevant weight bearing positions included sitting upright unsupported, with lumbar support (shown here) and slumped (also shown here). A standing position, which includes lumbar support is also shown here. Intradiscal pressure in this position was originally measured by Nachemson (1964) showed that intradiscal pressure to be 500-800 N for a 75 Kg man. See .

    Upright sitting, slumped.The usual position and was represented as 30% by students at Cambridge in a quick survey. Intradiscal pressure /load measured by Wilke (2001) was 0.48MP and by Sato 1127 kPa , 800N. This was less than sitting upright and can be explained by the pressure relieving effect of the abdominal cavity.

    Upright sitting with lumbar (not iliac) support. As can be seen, the support is applied above the Iliac crest and can be expected to have an opposite effect at the lower 2 joints (Gorman). This is shown to be so.

    In the flexed sitting view (left), It can be seen that there is an adverse posterior position of the Nucleus Pulposus (NP) of the vulnerable L4/5 & L5/S1 discs. When compared to non-loaded, uncompressed disc scans (right), the NP has migrated, or in clinical terms there is retropulsion, to the position that is potentially dangerous.

    This is precisely what Cyriax had postulated in 1945.

    Unexpectedly confirming the view postulated by JD Gorman the scan shows that support at the upper lumbar joints has a reverse, adverse, effect at the important lower joints. Lumbar v. pelvic support→ See Gorman’s view→

    Building a Rationale for Evidence-Based Prolotherapy in an Orthopedic Medicine Practice: Part IV: Diagnosing Linked Prolotherapy Targets by Applying a Data-based Biotensegrity Model

    Part I of this series presented the logical development of Prolotherapy, highlighting Empirical, Deductive, Inductive, and Abductive analytical reasoning (IDEA). 1 Part II discussed the application of the IDEA-based Scientific Method for evaluating Prolotherapy in an Orthopedic Medical setting. 2 Part III presented a data-based case series study of chronic back pain due to sacroiliac joint dysfunction (SIJD) treated by Prolotherapy. 3 Although that study was nonrandomized and uncontrolled, it strongly suggested important clinical correlations supporting and elucidating the nature of the injury—as well as the efficacy of the Prolotherapy.

    This, Part IV, employs lessons learned from the Part III case series study to expand the Chronic Back Pain-SIJD-Prolotherapy correlation. In doing so, this article provides a definitive description of clinically applied Biotensegrity. It presents a total body system of potential targets for Prolotherapy consideration—introducing a functional model of tension-compression injuries with a general grading system of Biotensegrity injury severity.


    Gravity exerts a constantly compressive force on all tissues: the human body moves through a sea of gravitational compression. All tissues must counter that force with equal or greater biologically-derived tension-compression forces. This complex geo-biological structural balance is termed “Biotensegrity,” as championed by Steven Levin, MD, and adapted from Buckminster Fuller’s “tensegrity,” which is a contraction of “tensional integrity.” The companion to tensegrity is “floating compression,” so labeled by Kenneth Snelson. 4, 5

    Organic structures that facilitate the transferring and stabilization of Biotensegrity tension-compression forces exist at every biological structural level. Those structures form a kinetic chain of interoperative components that extend from individual intracellular structure, to specific tissue composition, to whole organ architecture, on to organ system integration.

    The organ system that generates major counter-gravitational Biotensegrity forces is the neuromusculoskeletal system (NMS). A totally integrated NMS facilitates efficient, balanced ambulation and other movement—as well as minimization of compression-related neurological injury—all of which is centered at the joints. Joint tissues comprise the epicenter of a natural struggle at which there is a constant biodynamic flux in the balancing of NMS-derived tension and compression forces against persistent gravitational compression. Osteopathy, Rolfing (Structural Integration), and Pilates have long emphasized the clinical importance of balancing these countering forces.

    In an ideally uninjured state of normally functional Biotensegrity, the countering of gravity by ligamentous, muscular, and bony tension and compression is biodynamically balanced and synergistic. In the compromised state of Biotensegrity dysfunction, those NMS forces become unbalanced and dys-synergistic—accompanied by a variable extent of neuroprotective postural adaption. This is clinically manifested by tension-driven NMS soft tissue stretch, stress, strain, sprain, tear, and avulsion with bony tissue osteoneogenesis (i.e., spurring) injuries and compression-driven NMS soft tissue shortening or nerve impingement and bony tissue remodeling, osteoneogenesis, stress fracture, or osteoarthritic injuries.

    “Biotension” injury (versus “biocompression”) can be passive or active. Passive biotension injury results from:

    1. direct gravitational compressive force on ligaments, e.g., sacroiliac ligament sprain and collapse, or
    2. indirect muscular tensional force such as seen in compensatory leg shortening, e.g., Biceps femoris (hamstring) muscle ischial tendinosis of a compensatory functionally shortened leg.

    Active biotension injury results directly from muscular force actively causing a compensatory postural change, e.g., Tibialis posterior tendinosis causing adaptive supination in forming a compensatory functionally shortened leg.

    Tension-related lesions respond very well to Prolotherapy as a treatment of choice in restoring balanced, functional Biotensegrity. However, passive versus active tendon and ligament lesions may differ in their response to various proliferant delivery systems.


    Since early antiquity, the sacrum has earned the distinction of being the keystone to bipedal NMS form and function. Early Greeks referred to the sacrum as hieron osteon early Latin nomenclature referred to it as the os sacrum—in both cases meaning “strong, sacred, or holy bone.” 6 In pre-Cartesian philosophy, the sacrum was considered the seat of the soul. 7 In Slavic and German languages, it was referred to as the “cross bone,” (as in “transitional”). 8 It is clear that the Ancients had deduced that sacral integrity was fundamental to bipedal ambulation and related postural health.

    Volumes have been written about the manifold and complex physiologically normal sacral movements. The sacroiliac ligaments (SIL) and their companion iliolumbar ligaments (ILL) bear the burden of supporting those normal sacral movements under the force of gravity. The SIL and ILL comprise a kinetic chain of linked components that extend from one sacroiliac joint (SIJ) to the other SIJ when torqueing from one side to the other. In doing so, these ligaments bear at least half of the patient’s body weight from above the waistline. Additionally, these ligaments transfer all of the patient’s weight with every step that we take—as reported in one study, we might take up to 18,000 steps per day 9 —all in a gravitational field.

    As with every bone-to-bone-interface, there are the usual physiological restrictions and fixations of sacral movement that can occur within the normal arcs and ranges of movement. Gravitational force, however, is the proverbial bane to those physiological sacral movements, their weight-bearing sacroiliac ligaments, and their supporting muscles. Thus, a physiological joint restriction can become a pathological subluxation.

    Over time, therefore, the wear-and-(literally)-tear of normal sacral joint motion in gravity wages a predictably overwhelming physical toll on the tissues that support sacral form and function. When gravity wins out—and it often does—all of the normal sacral motions can virtually disappear in functional and therapeutic importance. The sacrum can ultimately assume a nonphysiological, side-bending, inferior displacement (i.e., subluxation)—as manifested by inferior displacement of the sacral base and sacral inferior angle and the displaced sacroiliac joint becoming immobile. This pathological sacral displacement is referred to, here, simply as “sacroiliac joint dysfunction” (SIJD), since patients can present with a mixed picture of subluxation that may be preceded by, or might alternate with, more physiological alignment abnormalities within the boundaries of normal range of motion.

    SIJD is primarily caused by SIL and ILL sprain injury with resultant ligament incompetence (e.g., lengthening, laxity, weakness). Although a patient presents with unilateral sacral displacement—and, often, with unilateral symptoms—the SIJ sprain lesion is almost always bilateral. This is due to the natural progression of the postural injury—due to the patient repetitively stretching through transitional, partially stressed, partially sprained SIJ and ILL ligaments on the initially extended side (e.g., the right SIL and ILL when rotating to the left) to the “end-organ,” fully stressed, fully sprained SIJ ligaments on the farthest extended side (e.g., the left SIL and ILL when rotating to the left), as illustrated by Ravin, et al. 10

    Right-handedness is found in 70-90 percent of the world population. 11 Right-handedness causes preferential turning to the left, which is correlated with right cerebral hemispheric dopamine predominance. 12 Of the 54 study patients requiring Prolotherapy in the Part III study, all were right-handed. There were no left-handed patients—they seemed to have been virtually spared. Could being left-handed in a right-handed world provide some protective balancing of tension-compression Biotensegrity and gravitational forces? It appears possible, especially when applying a functional Biotensegrity model, as described in this article. The relevance of right versus left-handedness to SIJD needs further study.

    Also shown in the Part III study, SIJD became evident by the average age of 43 and 45, female and male, respectively. 3 However, the ratio of females to males was 3 to 2 and females presented as early as their mid-teens ( i.e., 14 years) whereas the youngest male was 26 years old. Increased female propensity for SIJD was associated with increased signs of general ligament laxity (e.g., earlier onset of Pes planus, multiple joint hypermobility, and multiple sprain injury). Estrogen, progesterone 1 3 and relaxin 14 hormone-derived and familial genome-derived general ligament laxity have been observed to confound the natural forces of Biotensegrity, upsetting the delicate balance between biologically-derived tension and compression forces. Thus, such “ligament lax” individuals tend to experience a greater incidence of tension-related stretch, stress, strain, sprain, tear, or avulsion injury and compression-related shortening, impingement, erosion, or impact injuries.

    Summarizing, the following forces can cause injury to sacroiliac and iliolumbar ligaments:

    • Primarily , life-long weight-bearing and transfer of gravitational and Biotensegrity forces.
    • Life-long low back postural torqueing force from repetitive rotational twisting of the low back at the lumbar-sacral junction from one side to the other—possibly accentuated by right-handedness.
    • Secondarily , decompensatory postural habits secondary to Biotensegrity imbalance remote to the sacroiliac joint—e.g., secondary to Pes planus.
    • Traumatic force directly delivered to the sacrum, e.g., falling onto the sacral-ischial anatomy, or indirectly through the legs—e.g., falling onto the feet and legs, experiencing excessive traction on a leg.
    • Traumatic force directly delivered to the sacrum from the vertebral column and upper body—e.g., falling onto the upper body, heavy weight lifting—all aforementioned primary and secondary forces being potentially accentuated by general ligament laxity.

    In the Part III study, 3 54 patients presenting with back pain and unilateral SIJD required Prolotherapy for stabilization. Forty four (81%) of those requiring Prolotherapy presented with Left SIJD (LSIJD). Ten (19%) patients presented with the mirror-image Right SIJD (RSIJD).

    Using the LSIJD patients as an example, the sacrum—by general definition—was non physiologically side-bent and displaced (i.e., subluxed) inferiorly on the left while rotated anteriorly to the right at both its left base and inferior angle. (See Figure 1.) This subluxed left SIJ was markedly restricted in motion. The left ilium—as found in 93% of cases in the Part III study—was flexed anteriorly and the right ilium extended posteriorly. The causative SIL and ILL ligament sprains often generated left-to-central low back pain with variably referred pain to the left buttock, hip, groin, or down the left leg, mimicking sciatica.

    Potential Prolotherapy Targets in LSIJD : In the Part III study,3 23 (30%) of the initial 77 male and female patients responded to OMT sacral stabilization, alone. The other 54 (70%) patients failed to respond to OMT and required bilateral Prolotherapy to ultimately stabilize the sacrum. Therefore, definitive treatment of LSIJD consists, first, of OMT applied to the sacrum, iliac bones, and vertebral column. If the sacrum remains unstable after OMT, then those patients deserve treatment by appropriate Prolotherapy of the following, underlying tension-related injuries—bilaterally:
    • The iliolumbar ligament (ILL) at the proximal (transverse processes of L4 and L5) and distal (superior anterior medial iliac crest) bony attachments
    • The short posterior sacroiliac ligament (SIL) at the proximal sacral and distal iliac superficial fiber and deep fiber bony attachments
    • The long posterior sacroiliac ligament, if painful and tender, at its proximal attachment to the inferior posterior superior iliac spine.

    Severity Grading : Biotensegrity lesions requiring only OMT or Prolotherapy treatments to reach overall normal sacral, vertebral, and lower extremity stability in all kinetic chains are generally graded as Grade I of IV in severity.

    RSIJD forms a mirror-image of sacral and pelvic displacements in abnormal form and function. Patients with RSIJD routinely present with the exact same Prolotherapy targets and grading severity—they are usually just reversed left to right in degree of severity of ligament injury. Remember that these are usually bilateral lesions.


    SIJD with its unlevel sacral base can create tension-related stretch, stress, strain, and sprain joint injuries, compression-related joint injuries, dysfunction, and pain that can be distributed along three related kinetic chains of neuromusculoskeletal structures. Each kinetic chain extends from the site of primary sacral injury through multiple sites of secondary, compensatory NMS injuries to the end of that physical rotational moment of Biotensegrity tension-compression influence.

    In the Part III study, 3 LSIJD was found to universally demonstrate three specific kinetic chains:

    • Compensatory lumbar levoscoliosis (CLLS) accompanied by a thoracic dextro and cervical levoscoliosis—extending from the primary sacral injury through a scoliotic vertebral column to the nuchal line
    • Left functionally short leg (LFSL)—extending from the primary sacral injury through a functionally short leg to that plantar arch
    • Right functionally long leg (RFLL)—extending from the primary sacral injury through a functionally long leg to that plantar arch.

    In the same study, RSIJD was universally found to demonstrate the mirror-opposite patterns—i.e., compensatory lumbar dextro scoliosis, right functionally short leg, and left functionally long leg. In any case, the three secondary subpatterns of SIJD offer a wide spectrum of Prolotherapy-rich diagnostic and therapeutic targets of potentially great importance—from the plantar arch to the nuchal line.


    In the sitting or standing neutral position, the vertebral column normally rises plumb vertically from the normally level sacral base. During normal ambulation, however, the sacral base alternately shifts from level to unlevel from one side to the other, dropping slightly to the side of the unweighted leg in each early swing phase. The iliac bones synchronously and alternately rotate with the iliac bone of the unweighted leg flexing anteriorly in the early unweighted swing phase and the opposite iliac bone extending posteriorly in the early weighted stance phase.

    Importantly, as a result of the alternating sacral base orientation during ambulation, the lumbar vertebrae alternately side-bend toward the weighted side and rotate anteriorly toward the opposite, unweighted side in normal, coupled Type I motion. The thoracic vertebrae synchronously alternate in their side-bending toward the unweighted side and rotating anteriorly in normal, coupled Type I motion toward the weighted side. The cervical vertebrae alternately side-bend and rotate anteriorly to the same side in coupled Type II motion—both side-bending and rotating toward the weighted side. Thus, during normal ambulation, the three vertebral sections alternately “undulate” from levo to dextro “normoscoliosis” with each right to left weight-bearing step—side-bending and rotating as a synchronized, balanced kinetic chain of joints from the sacral base and iliac crests (i.e., the inferior NMS anchor point) through all the vertebrae up to the occiput and extending by the suboccipital musculature to the occipital nuchal line (i.e., the superior NMS anchor point).

    In comparison, patients with the sacral changes of LSIJD develop a fixed compensatory lumbar levoscoliosis (CLLS) due to the fixed, inferiorly displaced, left sacral base. And, the thoracic and cervical vertebral segments develop their fixed dextro and levo scoliotic arcs, respectively. This nonphysiological deformity is characterized by persistent lumbar right side-bending with left lumbar vertebral rotation, resembling a Type I motion that has become nonphysiologically persistent—the thoracic and cervical segments following suit with their respective scoliotic arcs and types of motion. (See Figure 2.) Consequently, the scoliotic vertebral segments do not move on ambulation with normally balanced symmetry or synchrony—they “undulate” unnaturally, favoring the aforementioned three persistently side-bent arcs with persistent vertebral rotational restrictions.

    Figure 2. Compensatory dextrolumbar scoliosis (CDLS) in LSIJD. Schematic showing dextrolumbar, levothoracic, dextrocervical, T12, T4 costovertebral and nuchal line components of CDLS with passive tension (PT), active tension (AT), and compression (C) related potentially injurious Biotensegrity forces. L = left R = right A = anterior P = posterior NL = nuchal line + = vertebral posterior rotation.

    These sacral, ilial, and vertebral misalignments may transiently return to normal position on manual manipulation, but they usually return to their abnormal positioning due to the persistently unlevel sacral base of LSIJD caused by sacral/ilial ligament incompetency. Until the sacrolumbar ligament injuries are healed and the sacral base is restored permanently to its normally level alignment, the scoliosis will resist manual and rehabilitative therapies.

    The three sequential arcs (i.e., lumbar, thoracic, and cervical) of persistent vertebral side-bending and rotation in CLLS of LSIJD exert constant tension-compression forces on their component vertebral soft and osseous tissues. Chronic intermittent convexity creates persistent passive tension. Chronic intermittent concavity creates persistent compression with active tension. These abnormal dynamics result in predictable tension-compression injuries that manifest as numerous Biotensegrity symptomatic and physical lesions up and down the compensatory scoliotic vertebral column.

    In CLLS of LSIJD, the lumbar levoscoliotic arc from L5 to L1 is often the most acutely angulated of the three vertebral segments. On the left, convex side of the lumbar segment, there are tension-related 1) chronic stretch, stress, strain, and sprain injuries of left-side inter and paravertebral ligaments and muscles, producing 2) left-side facet joint hypermobility with related left-side facet degenerative changes, possibly including various grades of spondylolesthesis, and 3) left-side ligament-muscle pain and dysfunction. On the right, concave side, there are compression-related 1) right-side facet compression with related right-side facet degenerative changes 2) compression of right-side intervertebral discs 3) chronic shortening of right-side inter and paravertebral muscles exerting active tension 4) gradual wedge-shaped remodeling of the osseous vertebral bodies due to selective compression of the vertebrae on that right side and 5) related right-side articular-muscular-neurological pain and dysfunction. Nerve impingement, exacerbation of degenerative disk disease, and/or compression fracture may be an end result, especially on the right, concave side with neurological symptoms of true sciatica possibly being radiated down the right leg.

    Moving upward, the vertebral segment from about L1 to T11 is positioned in a unique crossover of the lumbar levo and thoracic dextroscoliotic arcs. This short transitional segment is submitted to stretch, stress, strain, and sprain forces due to repetitive abnormal side-to-side bending and side-to-side rotation—often found fixed in persistent left vertebral rotation. As a result, the patient may report a persistently nagging lower back discomfort and dysfunction with the patient often pointing directly at T12 as the source of “weird” discomfort. As explained below, hypertonic, spasmed Quadratus lumborum muscles can significantly add to this L1 to T11 dysfunction. This L1 to T11 vertebral dysfunction often persists after successful restabilization of the sacral base.

    Along the thoracic spine region from T10 to T1, the vertebral column forms a thoracic dextroscoliotic arc with right vertebral (Type I) rotation. On the right convex side of that thoracic segment, there are the typical passive tension-related chronic stretch, stress, strain, and sprain injuries of ligaments and muscles and facet degenerative changes. On the left, concave side, there are the typical compression-related injuries with active tension. Again, nerve root impingement and/or compression fracture may result, predominantly on the left concave side.

    Along the vertebral segment, variably, from about T3 to T5 , the persistent thoracic dextroscoliotic left side-bending provokes an accentuated right vertebral rotation, all of which provokes right costovertebral joint and rib posterior displacement with associated ligament and muscle stretching and sprain injury along that passive tension-related convex arc. Often, the result is persistent right interscapular discomfort and pain with a discernible, tender, right paravertebral, parascapular, kyphoscoliotic hump caused by the posteriorly displaced costovertebral joints and ribs.

    Along the cervical spine region , the vertebral column is involved in the last, usually milder, cervical levoscoliotic arcing with left vertebral (Type II) rotation—which finally positions the head over the body’s newly adjusted center of gravity. On the left, convex side, there are the typical passive tension-related chronic stretch, stress, strain, and sprain injuries of ligaments and muscles with facet degenerative changes. On the right, concave side, there are the typical compression-related injuries with active tension extending up to the nuchal line. Again, nerve root impingement and/or compression fracture may be an end result, especially on the right, concave side with sensory or motor symptoms often being referred to the right arm.

    The more extreme mobility demands made on the neck can create an increased likelihood of manifesting scoliotic stress on susceptible neck tissues. The shortened, actively tensioned paraspinal and suboccipital muscles on the right, concave side of the neck are particularly prone to stretch, stress, strain, sprain, and spasm after repetitive side-bending and turning. Consequently, the suboccipital muscles, particularly, often are tender at their at their vertebral and nuchal line attachments causing chronic tension neck pain and headaches that can radiate over the head often to the ipsilateral eye or TMJ. These cervical tension-compression injuries can be aggravated by other factors, such as occupational or training positional-postural stress, shoulder injury, accidental whiplash—and even Pes planus, very remotely.

    The Quadratus lumborum (QL) arises by aponeurotic fibers from the iliolumbar ligament and directly from the adjacent, posterior-medial iliac crest and inserts onto the inferior margin of the twelfth rib and the transverse processes of L1 to L4. In LSIJD, the left Quadratus is actively recruited to left side-bend the lumbar vertebral segment as a correction of the lumbar levoscoliotic right side-bending and to lift the left ileum—and, indirectly, the left sacral base—in the unweighted left leg swing phase. This action helps to partially straighten (i.e., decompress) the lumbar concave arc and minimize potential nerve impingement injuries along that lower right lumbar concavity when the left leg is unweighted. Over time, chronic Quadratus activation can result in QL muscle shortening, trigger point generation, decompensatory spasm, degenerative tendinosis, and debilitating pain. The right QL, also, is usually posturally and actively shortened, being located within the concave lumbar arc—thus, also easily stressed, strained, and sprained. As aforementioned, either hypertonic, spasmed QL can aggravate the symptoms of restrictive movement along the abnormal T11-L1 segment.

    As another compensatory postural adaptation to the unlevel sacral base and resultant scoliosis in LSIJD-CLLS, the right shoulder is often dropped lower and can be more anterior than the left—as seen in 34 (63%) of 54 Prolotherapy cases in the Part III study. This is due to chronic activation of the posterior oblique sling, which consists of the right Latissimus dorsi and left Gluteus maximus muscle connected via the midline thoracolumbar aponeuroses. Chronic sling activation in the early to mid unweighted left leg swing phase assists in lifting the left sacral base, but often results in muscle shortening, trigger points, spasm, tendinosis, and pain of the two sling muscles.

    A chronically shortened right Latissimus dorsi (LD) can aggravate active tension-related tendinosis at its attachment to the floor of the right humeral intertubercular groove (bicipital groove) and a chronically shortened left Gluteus maximus can aggravate active tension-related tendinosis at its attachments to the ilium or greater trochanter. Chronic humeral internal rotation by the shortened LD can be accompanied by recruitment of Subscapularis internal rotation in assisting the sling compensatory effort and cause active tension-related tendinosis of the Subscapularis attachment to the lesser tubercle—as well as there occurring chronic passive tension-related sprain of the posterior capsular ligament and conjoining muscle tendons. Chronic dropping (lowering) of the shoulder effectively increases the angle of resting aBduction, which increases the exposure of the Supraspinatus, Infraspinatus, Subscapularis, and long head of the Biceps to impingement injury—as well as labral and other articular injuries of chronic shoulder joint misalignment.

    Potential Prolotherapy Targets in CLLS : Definitive treatment of patients with CLLS consists, first, of OMT and Prolotherapy of the underlying LSIJD tension-related injuries. All patients who remain symptomatic of CLLS-related injuries deserve assessment of additional Prolotherapy of the following potential tension-related injuries:

    • L1 through L5 interspinous ligament, intervertebral facet joint ligament, and paraspinal and Quadratus lumborum tendon attachments, particularly along the left, convex lumbar arc
    • Generally, all T1 through T12 interspinous ligament, intervertebral facet joint ligament, and paraspinal tendon attachments, particularly along the right, convex thoracic arc
    • Specifically, T11 through L1 interspinous ligament, intervertebral facet joint ligament, and laminar tendon attachments on both sides along the T12 crossover zone
    • Specifically, T3 through T5 interspinous ligament, intervertebral facet joint ligament, laminar tendon, and costovertebral joint ligament attachments, particularly along the right, convex thoracic arc
    • Cervical spine interspinous ligament, intervertebral facet joint ligament, and laminar tendon attachments, particularly along the left convex cervical arc from C7 through—but not above—C3 it is generally dangerous territory above C3, requiring advanced injection technique
    • Superficial and deep superior and inferior nuchal line suboccipital tendon attachments, particularly on right side
    • Left Quadratus lumborum attachments to the iliac crest and transverse processes of L1 through L4
    • Left posterior oblique sling tendon attachments, e.g., Latissimus dorsi and Gluteus maximus muscles
    • Rotator cuff tendon attachments—e.g., Subscapularis, Supraspinatus, Infraspinatus, and long head of the Biceps muscles—as well as superior labral and posterior capsular ligament attachments.

    While treating these potential target sprain injuries of CLLS by OMT and Prolotherapy, a concerted effort is required to rehabilitate the entire scoliotic vertebral column, including its supportive fascia, ligament, musculature, and osseous components. This should include Neural Therapy of muscle trigger points Rolfing (Structural Integration) to balance myofascial length and strength Pilates to balance and increase upper and lower body core strength and movement Physical Therapy to treat specific, persistent NMS dysfunctions and/or Orthotic treatment of coexistent Pes planus to eliminate any pronation-external rotation effect through either of the two lower extremity kinetic chains. One must remember that what has usually taken the patient years or, even, decades to develop often takes months to years of patient rehabilitation to resolve, including the vertebral remodeling.

    Severity Grading : Biotensegrity lesions characteristic of CLLS are generally graded as Grade II of IV in severity.

    Compensatory lumbar dextro scoliosis (CLDS), routinely found in RSIJD, presents with the mirror-image opposites of tension-compression injuries and equal grading severity requiring consideration of treating those injuries with appropriate Prolotherapy.


    A compensatory left functionally short leg (LFSL) characteristically occurs with LSIJD. The physical causes of functional leg length discrepancy are manifold and can be attributed to Biotensegrity forces acting from above and/or below the level of the lumbar-sacral joint. The dropped left sacral base left iliac (anterior) flexion and the lumbar right side-bending with left rotation of compensatory dextroscoliotic L4 and L5 vertebrae seen in LSIJD—each alone or combined—can result in a left functionally shortened leg. However, the presence of an unlevel sacral base can be counted as the primary cause until it has been rectified. The leg can be anywhere from 2 to 15 or more millimeters functionally short. A truly anatomically short-long leg is very uncommon and needs to be confirmed carefully with exact radiological leg length measurement.

    The major Biotensegrity dysfunctions inherent in LFSL are consequent to the patient’s unconscious, automatic effort to biomechanically lengthen that functionally shortened left leg—and physically raise the dropped left sacral base to reduce right lumbar nerve compression—by actively extending, plantar flexing, and internally rotating (i.e., supinating) the left foot and ankle with each left step at the time of heel strike. This abnormal posturing of the lower extremity can cause multiple passive tension-related stretch, stress, strain, spasm, sprain, and tear injuries along the dorsolateral foot, lateral ankle and knee, and posterior-lateral hip joints.

    The counter Biotensegrity forces of compression and active tension adversely affect the corresponding posteromedial aspects of the functionally short lower extremity from the plantar arch to the hip. Compression on the medial aspect of all lower extremity joints causes relative sparing of medial ligaments and muscles from tension-related sprain injuries. (See Figure 3.) These Biotensegrity lesions comprise what has been labeled as the “Short Leg Syndrome.”

    Figure 3. Left functionally short leg (LFSL). Schematic showing passive tension (PT), active tension (AT), and compression (C) related potentially injurious Biotensegrity forces. L = left R = right A = anterior P = posterior.

    At the left foot, constant passive, dorsilateral, tensional stretching from compensatory, adaptive supination can ultimately result in chronic passive tension-related sprain injury of dorsolateral foot ligaments and passive tendinosis at the Peroneus brevis and longus tendon lateral foot attachments. In the more extreme case, there is a predilection for occurrence of unilateral Lisfranc cuneiform-second metatarsal plantar ligament sprain injury and deformity of the left midfoot, as well as Morton’s neuroma between the third and fourth intermetatarsal joints of the left forefoot.

    The usual sequelae of Pes planus (e.g., flattened arch Hallux valgus and bunion) are often relatively spared compared to the other foot. In fact, the left foot may take on the unweighted appearance of being more varus, cavus, and internally rotated than the right (i.e., supinated) due to postural remodeling during chronic intermittent supination while ambulating. Chronic activation of the Tibialis posterior in its repetitive attempts to raise (plantar flex) and invert the flattened arch can also cause active, tension-related degenerative tendinosis at its medial and plantar midfoot tendinous attachments.

    Posterior column and plantar-wise, chronic, active compensatory shortening of the hamstring-gastrocnemius-Achilles tendon-plantar fascia kinetic chain occurs during the chronic intermittent supination. This chronic active intermittent posterior column shortening acted upon by the tension generated on stance phase toe off may result in left lateral plantar fasciosis and Achilles tendinosis—as well as left ischial tendinosis remotely proximal at the left ischial tuberosity.

    The compression-related impact upon left heel strike, compounded by the posterior column and plantar shortening and tension, can easily aggravate the already stimulated tension-related left lateral plantar fasciosis and Achilles tendinosis. Compression-related metatarsal stress fractures may also occur.

    At the left ankle, constant, active tensional stretching often results in lateral ankle ligament stretch, stress, strain, sprain, and even avulsive injuries. Such an ankle can adopt a varus deformity and is particularly prone to inversion sprain accident and injury consequent to the chronic supination at heal strike. Chronic medial compression upon heel strike impact can result in medial ankle-foot joint degenerative arthritic changes.

    At the left knee, Genu varus can occur with passive tension-related stress along the lateral aspect often results in predominant sprain injury of the lateral knee ligamentous structures, including the fibular (lateral) collateral, lateral coronary, and posterior lateral corner ligaments. Corresponding displacement of the proximal fibular head also can occur due to capsular ligament sprain injury. The left posterior cruciate ligament is relatively spared injury from any accentuated knee internal rotation-lateral tension due to its relatively short span and substantial strength—but there is always a possibility.

    At the left patella, chronic intermittent supination and internal rotation of the distal lower extremity exert a medial compression-related force on the patella, forcing it to the lateral side of its intercondylar groove. This lateral patellar misalignment can result in symptoms of predominantly lateral retropatellar chondromalacia—and may be potentially confused with an abnormal Q angle and mistreated surgically. Chronic medial compression at the knee also can result in accentuated erosion of the medial condylar articular cartilage surface with symptoms and signs of accelerated medial osteoarthritis. Additionally, chronic shortening of the posterior muscular column due to chronic supination can result in compensatory, active tension-related, left quadriceps strain and sprain and left patellar and quadriceps tendinosis (unilateral jumper’s knee). This unilateral presentation is similar to the bilateral jumper’s knee presentation seen in bilateral Pes cavus without SIJD.

    At the left hip, chronic supination and internal rotation exert chronic passive tension-related forces to the posterior lateral hip capsular ligament and the hip external rotator muscle (i.e., Gluteus maximus, Piriformis, Gemelli, Obturator femoris) tendon attachments. Chronic intermittent activation of the internal rotators (i.e., Gluteus minimis and medius and Tensor fascia latae)—and the aDductors—may produce easily stimulated spasm, trigger points, and a degenerative tendinosis at those tendinous attachment sites—often confused with and mistreated steroidally as trochanteric bursitis.

    Potential Prolotherapy Targets in LFSL : Definitive treatment of patients with LFSL consists, first, of OMT and Prolotherapy of the underlying LSIJD and CLLS injuries. All patients symptomatic of LFSL deserve assessment of additional Prolotherapy of the following tension-and-impact-compression-related injuries:

    • Dorsilateral, plantar left foot ligament attachments—e.g., calcaneocuboid (bifurcate), dorsal calcaneonavicular, talocalaneonavicular (in sinus tarsi), cuneiform-second metatarsal (Lis Franc), and 3rd to 4th intermetatarsal (Morton’s) ligaments
    • Lateral left foot Peroneus (Fibularis) brevis tendon attachment to the fifth metatarsal head
    • Plantar left foot fascia-ligament attachment to the lateral and mid-calcaneus
    • Medial left foot Tibialis posterior tendon attachments, particularly at the navicular
      Lateral left ankle ligament attachments—e.g., anterior and posterior talofibular and calcaneofibular ligaments
    • Left Achilles tendon attachment to the left calcaneus
    • Lateral left knee and fibular ligament attachments—e.g., fibular-collateral, lateral coronary ligaments, posterior lateral corner ligaments
    • Left posterior cruciate ligament attachments—possibly
    • Left Quadriceps and patellar tendon attachments to patella and tibial tubercle
    • Treating the sacrum, lateral knee structures, and whatever Pes planus exists by Prolotherapy and orthotic therapy help to correct patellar lateral misalignment and reduce medial plateau compression
    • Left hamstring tendon attachment at the left ischial tuberosity
    • Posterior-lateral hip capsular ligament attachments
    • Lateral hip external rotator tendon attachments —e.g. Piriformis, Gemelli, Obturators, Quadrator femoris)—along the posterior-superior greater trochanter
    • Lateral hip internal rotator and adductor tendon attachments—e.g., Gluteus minimis and medius and Tensor fascia latae—along the external iliac crest and antero-lateral surface of the greater trochanter.

    Severity Grading : Biotensegrity lesions characteristic of LFSL are generally graded as Grade II of IV in severity.

    Compensatory right functionally short leg (RFSL), routinely found in RSIJD, presents with the mirror-image opposites of tension-compression injuries and equal grading severity requiring equal consideration of treating those injuries with appropriate Prolotherapy.


    A compensatory right functionally long leg (RFLL), by definition, coexists with the left FSL in patients with LSIJD. It usually results from there being a persistently elevated right sacral base with right iliac extension and lumbar levoscoliosis/left vertebral rotation.

    The major Biotensegrity dysfunctions in RFLL are consequent to the patient’s unconscious, automatic effort to biomechanically shorten that functionally long leg by actively pronating and externally rotating the foot and ankle, thereby physically flattening the plantar arch. This also effectively helps to lower the high side of the unlevel sacral base and reduce the threat of nerve compression along the levolumbar concave arc. This dysfunctional lower extremity posturing can cause multiple passive tension-related stretch, stress, strain, spasm, sprain, and tear injuries along the medial aspect of the right foot, ankle, knee, and anterior-medial hip. In parallel, there are counter Biotensegrity forces of compression and active tension impacting on all lower extremity lateral-posterior compartment tissues. Compression on the lateral aspect of all lower extremity joints causes relative sparing of the lateral ligaments and muscles from tension-related sprain injuries. (See Figure 4.) These Biotensegrity lesions comprise a “Long Leg Syndrome,” which is equally as important as its “short leg” counterpart.

    Figure 4. Right functionally long leg (RFLL). Schematic showing passive tension (PT), active tension (AT), and compression (C) related potentially injurious Biotensegrity forces. L = left R =- right A = anterior P = posterior.

    At the right foot, constant medial, chronic passive tensional stretching due to excessive unilateral pronation can ultimately result in stretch, stress, strain, sprain, or tear injury of medial plantar ligaments and passive tendinosis of the Tibialis posterior tendon medial and plantar attachments. The usual sequelae of Pes planus (e.g., flattened arch, Hallux valgus, and bunion) are often relatively accentuated compared to the other foot, as well as persistent external rotation in the supine position unilateral Hallux limitans or rigidis also can result. Chronic intermittent activation of the Peroneus brevis to evert the foot can also cause active tension-related degenerative tendinosis at its lateral foot insertions.

    Abnormally directed heel strike impact of the chronically actively pronated-externally rotated right foot-ankle along with a a chronically passively stretched medial arch ligament, plantar ligament, and Achilles tendon architecture can aggravate compression-related medial plantar fasciosis. Chronic lateral compression with heel strike impact can result in lateral foot-ankle joint degenerative arthritic changes.

    At the right ankle, constant passive tensional stretching predominantly results in medial ankle ligament stretch, stress, strain, and or sprain injuries. Such an ankle can adopt a valgus deformity and is prone to eversion sprain accident and injury. Compression-related articular injury is predominantly found on the lateral side.

    At the right knee, Genu valgus can occur with chronic passive tension-related stress along the medial aspect often results in sprain injury predominantly of the medial knee ligamentous and muscular components, including the medial collateral and medial coronary ligaments and the Popliteus, Semimembranosis, and Pes anserinus tendinous tibial attachments. The right anterior cruciate ligament also is at an increased risk of passive tension-related sprain, especially during accentuated foot-ankle pronation-external rotation-eversion.

    Chronic pronation and external rotation of the distal lower extremity and resulting lateral compression tend to force the patella to the medial side of its intercondylar groove. This medial patellar misalignment can result in symptoms of predominantly medial retropatellar chondromalacia—and may be potentially confused with an abnormal Q angle and mistreated surgically. Chronic lateral compression at the knee can result in selective erosion of the lateral condylar articular surface. This can result in symptoms and signs of osteoarthritis predominantly on the lateral condylar surface. This unilateral presentation is similar to the bilateral knee presentation seen in bilateral, severe Pes planus without SIJD.

    At the right hip, chronic pronation and external rotation exert chronic passive tension-related forces to the anterior hip capsular ligaments, the hip internal rotator muscles (i.e., anterior fibers of Gluteus minimus and medius and tensor fascia latae), and the hip aDductors. This often can cause a tension-related tendinosis, particularly, at the Gluteus minimus and medius femoral trochanteric attachments, which can be confused with and is often mistreated steroidally as trochanteric bursitis, and the aDductor attachments along the pubic ramus.

    Constant overuse activation of the external rotator muscles may eventually produce decompensatory fatigue with the advent of easily triggered muscle spasm, trigger points, and chronic active degenerative tendinosis at those tendinous attachment sites. The diagnosis of a chronic active tension-related “Piriformis Syndrome”—which is often thought to be totally isolated and “idiopathic” or is misdiagnosed as “bursitis” and/or mistreated with inappropriate steroid injection (i.e., for an inflammatory process or “tendonitis” that does not exist)—is common in RFLL. The excessive vaulting nature of the long leg gait also can exert accentuated compressive force on the hip articular and labral structures, placing that hip at greater risk of wear-and-tear joint articular surface and labral damage.

    Potential Prolotherapy Targets for RFLL : Definitive treatment of patients with RFLL consists, first, of OMT and whatever Prolotherapy is required of the underlying LSIJD, CLLS, and LFSL injuries. All patients who remain symptomatic of RFLL deserve assessment of additional Prolotherapy of the following tension-and-impact-compression-related injuries:

    • Medial-plantar foot ligament attachments—e.g., plantar calacaneonavicular (spring), short and long plantar, 1st tarsometatarsal ligaments—and Peroneus brevis tendon attachments
    • Plantar fascial attachment from the medial to mid-calcaneus
    • Peroneus brevis tendon attachment at tuberosity of the 5th metatarsal bone
    • Medial ankle ligament attachments—e.g., deltoid ligament
      Medial knee ligament attachments—e.g., medial collateral and medial coronary ligaments
    • Right anterior cruciate ligament attachments
    • Medial tendon attachments—e.g., Popliteus, Semimembranosis, and Pes anserinus muscles
    • Treating the sacrum, medial knee structures, and whatever Pes planus exists by Prolotherapy and orthotic therapy helps to correct patellar lateral misalignment and reduce lateral plateau compression
    • Anterior hip capsular ligament attachments
    • Lateral internal rotator pelvic and greater trochanter tendon attachments—e.g., Gluteus minimis and medius muscles—and pubic ramus aDductor tendon attachments
    • Lateral hip external rotator pelvic and greater trochanter tendon attachments—e.g., Piriformis, Gemilli, and Obturator muscles.

    Severity Grading : Biotensegrity lesions characteristic of RFLL are generally graded as Grade II of IV in severity.

    Compensatory left functionally long leg (LFLL), routinely found in RSIJD, presents with the mirror-image opposites of potential Prolotherapy targets and equal grading severity requiring equal consideration of treating the mirror-image targets for Prolotherapy.


    In the more usual presentation of the LSIJD version of SIJD, the left ilium is anteriorly flexed and the right ilium is posteriorly extended. Consequently, the iliolumbar ligaments perform a tethering function, limiting L4-5 vertebral rotation—thus, limiting right lumbosacral side-bending.

    However, if the left ilium rotates and extends posteriorly and right ilium rotates and flexes anteriorly, the lumbar levoscoliotic curvature can be accentuated. The latter, “reversed” ilial flexion presentation was a rare but significant finding—3 of the 44 (7%) LSIJD patients—as observed in the Part III study. Such an ilial reversal can cause a paradoxical pulling on the L4 and L5 transverse processes by the iliolumbar ligaments that are anchored at the ilium, rotating those lumbar vertebrae even more anteriorly toward the left—and causing those vertebral bodies to side-bend to an even greater degree to the right in coupled Type 1 motion.

    These reversed ilial rotations can dramatically increase the severity of the lumbar levoscoliosis and drastically complicate Prolotherapy and post-Prolotherapy rehabilitation in SIJD. Moreover, this event significantly increases the potential severity of nerve root involvement on the right, concave side due to the greater lumbar curvature and increased biotensegritous compression see “A Perfect Storm,” below. The severely increased scoliosis consequent to such an ilial reversal calls for vigorous manual therapy, aggressive Prolotherapy, and disciplined rehabilitative therapy to all involved sacral, ilial, and vertebral structures. It requires a vastly different therapeutic strategy as to what structures should receive Prolotherapy, first, and what adjunct therapies need to be in play from the very beginning and thereafter. Otherwise, the patient is likely headed toward surgical intervention—and definitely deserves an Orthopedic consultation. Could accentuated scoliosis in SIJD be a cause of so-called “idiopathic” scoliosis?

    Severity Grading : Biotensegrity lesions characteristic of the accentuated scoliosis in LSIJD generated by right iliac flexion are generally graded as Grade III of IV in severity—and may progress to Grade IV with the advent of a “Perfect Storm.”

    The reverse of all the above events described in accentuation of lumbar scoliosis can be seen in RSIJD.


    Occasionally, one will detect sensory (e.g., paresthesia, numbness) and motor (e.g., foot drop) symptoms and signs indicative of right-sided L5-S1 and/or L4-L5 nerve root compression in a patient with a left-sided SIJD having the aforementioned CLLS, LFSL, and RFLL. Those truly neurological signs and symptoms can include transient to blatant right leg radicular paresthesia and pain with muscle weakness with early to profound right foot drop (i.e., true sciatica). It usually occurs on the side of the concave lumbar arc where the compression forces are the greatest—in the case of LSIJD, on the right, functionally long leg side. Bona fide sciatica can be easily confused with—or may be coexistent with—ligament referred pain (false sciatica) that can mimic true neurological sciatica—except for the motor symptoms. And, of course, there can be the atypical case of true nerve compression on the left, lumbar-concave side, but that is even more unusual because the convex arc of the right side-bent lumbar curve protects against that from happening.

    The combined occurrence of chronic ligamentous pain of all the components of LSIJD plus the acute pain and motor deficit of sudden nerve root compression can result in a catastrophic clinical picture that fits that of a “Perfect Storm”—an example of two clinically severe Biotensegrity “storms” colliding—i.e., that of severe LSIJD on the left side of the convex lumbar arc and severe nerve root compression on the right side of the concave lumbar arc. Such a patient can be in extreme distress, totally disabled—literally bent over by back pain—and even requiring being carried into the clinic. There is an even higher risk of such a “Storm” occurring when the scoliosis is accentuated by the aforementioned “reversed” ileil flexion.

    It is important to know that those emergency neurological symptoms and signs usually respond readily to manual therapy correction of the sacral displacement. Thus, leveling the sacral base can immediately reduce the left SIJD symptoms and signs, as well as reduce the right lumbar compressive forces on affected intervertebral discs, foramina, and the exiting nerve roots. Sixty seconds of applying very mild, low velocity, manual decompression of the sacral subluxation—thereby stabilizing the sacral base and, thus, reducing the right lumbar compression—usually can relieve all or most of the patient’s severe, acute discomfort. Then, instead of rushing into emergency back surgery, continued stabilization with a judiciously employed sacroiliac belt accompanied by aggressive Prolotherapy of the SIL and ILL over an average of three sessions followed by appropriate physical rehabilitation can save the patient’s day—and thwart unnecessary and potentially disabling surgery.

    Of course, one should always obtain a surgical consultation. And, it is occasionally necessary for surgical treatment of degenerative disk disease with persistent and extremely severe lumbar nerve root impingement—but not as often as surgeons and the public tend to think. Most often, the patient’s final narrative summary will document sustained patient relief after OMT and Prolotherapy with no need for surgical intervention. If back surgery is clinically mandatory, achieve sacral stabilization by Prolotherapy before the surgery, if at all possible.

    Severity Grading : Biotensegrity characteristic of severe LSIJD complicated by acute, severe nerve root compression are generally graded as Grade IV of IV in severity.

    The mirror-image of all the above events described for a “Perfect Storm” in LSIJD can be expected in RSIJD.


    Biotensegrity incorporates neuromusculoskeletal tension-compression structural elements and forces that not only counter gravity, viz., the classical Fuller-Snelson model, but also generate additional, adaptive posturing to minimize neurological injury. Stable sacral alignment is a keystone to maintaining functional Biotensegrity. Resolving chronic sacral displacement is the key to resolving many lesions of Biotensegrity dysfunction.

    Each patient with sacral dysfunction represents a unique Biotensegrity spectrum of balance and imbalance with infinite degrees of diagnostic possibilities. But, all three kinetic chains will be involved, presenting with their major defining manifestations to one degree or another. There can be variations of the theme with occasional exceptions to the general rules, particularly since many patients may be found caught in the midphase between a physiological restriction and a nonphysiological subluxation. But, recognizable patterns will emerge, offering hints as to where to look next. Such hints should guide decisions for staging treatment and joint stabilization based on analytical reasoning versus rote teaching. For example, if the lumbar spine is at risk of accentuated scoliosis in SJID, it may be wise to treat the iliolumbar ligaments with Prolotherapy and stabilize the lower lumbar vertebrae before treating the sacroiliac ligaments to stabilize the sacrum. Additionally, SIJD should be further scrutinized as a cause of idiopathic scoliosis and Prolotherapy with body work as treatment in lieu of a back brace and the Herrington rod.

    This series of four articles has presented a combination of Empirical, Deductive, Inductive, and Abductive clinical observations regarding back pain, sacral dysfunction, and Prolotherapy. Conclusions have been based on a Scientific Method approach to clinical practice—limited by nonrandomization. Many questions remain. For example, the Biotensegrity model described, here, needs to be further validated and characterized by other clinicians. Also, the differential effect of passive versus active tension on ligament and tendon needs to be further characterized. Biotensegrity patterns need to be further developed for various musculoskeletal regions other than the sacral kinetic chains herein described. Should preventive Prolotherapy be performed at nonpainful attachment sites that are at high risk of being subclinically injured?

    Given all the art and engineering forms available, there is no better model of Biotensegrity than the human form. Applying a functional Biotensegrity model clinically to sacroiliac sprain injury can reveal abundant targets for Prolotherapy from the plantar arch to the nuchal line, facilitating more efficacious diagnosis, treatment, and patient recovery—and prevention of further injury.


    1 Clark GB, Building a rationale for evidence-based prolotherapy in an orthopedic medicine practice. Part I. A short history of logical medical decision making. Journal of Prolotherapy. 2(Nov):512-5192010.

    2 Clark GB, Building a rationale for evidence-based prolotherapy in an orthopedic medicine practice. Part II. How to meld scientific methodology into the daily practice of prolotherapy. Journal of Prolotherapy. 3(Feb):582-5872011.

    3 Clark GB, Building a rationale for evidence-based prolotherapy in an orthopedic medicine practice. Part III: A case series report of chronic back pain associated with sacroiliac joint dysfunction treated by prolotherapy. A six-year prospective analysis. Journal of Prolotherapy. 3(May):632-6392011.

    4 “Tensegrity” Wikipedia. 26 March 2011:

    5 Levin S. The importance of soft tissues for structural support of the body. Spine. 9(May)1995.

    6 “Sacrum” Online Etymology Dictionary. 26 March 2011:

    7 Walker E. When I use a word. Pelvis. Brit Med J. Volume 325, Number 7358>BMJ325:264 doi:10.1136/bmj.3257538.264 (Published 3 August 2002).

    8 “Sacrum” Wikipedia. 26 march 2011:

    10 Ravin T, Cantieri M, Pasquarello G. Principles of Prolotherapy. Denver, CO: American Academy of Musculoskeletal Medicine 2008, p. 40-44.

    11 Right-handedness. Wikipedia. 26 March 2011:

    14 Dragoo JL, Lee RS, Benhaim P, Finerman GAM, Hame SL. Relaxin receptors in the human female anterior cruciate ligament. Am J Sports Med. 2003 July31(4):577-584.


    The author is grateful to Fran Brown, BA Matt Enos, CPI Allen Parker, EdD Michael Smith, MD Joseph Swartz, MD, for their generous editorial support. Many thanks to Nicole Baird and Travis Mitchell for their valuable staff support. I want to especially thank Thomas Ravin, MD, for his explaining the basics of Biotensegrity to me—many ski seasons ago. This article is dedicated to the memory of Michael W. Seamans, DO, who taught me the intricacy of sacral examination and subtlety of its manipulation.

    Shared Flashcard Set

    What are the functions of the pelvis and the perineium?

    • Pelvic Inlet
    • Plevic wall
    • Pelvic Outlet
    • pelvic Cavity
    • Pelvic Floor
    • Perineium
    • Is the superior rim of the pelvic cavity somewhat heart shaped and completely ringed by bone, is bounded posteriorly by the promontory of the sacrum (S1) and the anterior border of the ala of the sacrum (sacral part) , laterally by the arcuate or iliopectineal line of the ilium (iliac part) , and anteriorly by the pectineal line, the pubic crest, and the superior margin of the pubic symphysis (pubic part).
    • Is measured using transverse, oblique, and anteroposterior (conjugate) diameters.
    • Is crossed by the ureter, gonadal vessels, middle sacral vessels, iliolumbar vessels, lumbosacral trunk, obturator nerve, spermatic cord, round ligament of the uterus, sympathetic trunk, suspensory ligament of the ovary, etc

    What does the wall of the tru pelvis consist of?

    What are the two ligaments found in the wall?

    Walls of the true pelvis consist predominantly of bone, muscle, and ligaments, with the sacrum, coccyx, and inferior half of the pelvic bones forming much of them.

    Two ligaments-the sacrospinous and the sacrotuberous ligaments-are important architectural elements of the walls because they link each pelvic bone to the sacrum and coccyx. These ligaments also convert two notches on the pelvic bones-the greater and lesser sciatic notches-into foramina on the lateral pelvic walls

    Completing the walls are the obturator internuspiriformis muscles, which arise in the pelvis and exit through the sciatic foramina to act on the hip joint and

    What are the bones of the Pelvis?

    What are the divisons of the Pelvis?

    • Consist of the right and left pelvic bones, the sacrum, and the coccyx. The sacrum articulates superiorly with vertebra L5 at the lumbosacral joint.
    • The pelvic bones articulate posteriorly with the sacrum at the sacro-iliac joints and with each other anteriorly at the pubic symphysis
    • the pelvic bone above this line is the false pelvis, which is part of the abdomen
    • the pelvic bone below the line is the true pelvis, which contains the pelvic cavity

    The ilium is the superior,flattened fan-shaped part of the hip bone.

    The ala ofthc ilium represents he spread of the fan and the body the handle.

    The body of the ilium helps to form the acetabulum.

    The iliac crest the rim of fan has a curve that follows the contour of the ala between the anterior and posterior superior iliac spines.

    The nterior concave part of the ilium forms the iliac fossa.

    Has a body and ramus (L. branch). The body of the ischium helps form the acetabulum and the ramus of the ischium forms part of the obturator foramen.

    The large posteroinferior protuberance of the ischium is the ischial tuberosity the small pointed posteromedial projection near the junction of the ramus and body is the ischial spine.

    The concavity between the ischial spine and the ischial tuberosity is the lesser sciatic notch. The larger concavity, the greater sciatic notch , is superior to the ischial spine and is formed in part by the ilium.

    Is the expanded portion of the bony pelvis above the pelvic brim

    The greater pelvis (false pelvis, pelvis major) is the part of the pelvis :

    • Superior to the pelvic inlet.
    • Bounded by the iliac alae posterolaterally and the anterosuperior aspect of the S1 vertebra posteriorly.
    • Occupied by abdominal viscera (e.g., the ileum and sigmoid colon).
    • Is the cavity of the pelvis below the pelvic brim (or superior aperture) and above the pelvic outlet (or inferior aperture).
    • Has an outlet that is closed by the coccygeus and levator ani muscles and the perineal fascia, which form the floor of the pelvis.
    • link the axial skeleton (the skeleton of the trunk, composed of the vertebral column at this level) and the inferior appendicular skeleton (skeleton of the lower limb).
    • strong, weight-bearing compound joints, consisting of an anterior synovial joint (between the ear-shaped auricular surfaces of the sacrum and ilium, covered with articular cartilage) and a posterior syndesmosis (between the tuberosities of the same bones). The articular (auricular) surfaces of the synovial joint have irregular but congruent elevations and depressions that interlock differ from most synovial joints in that limited mobility is allowed, a consequence of their role in transmitting the weight of most of the body to the hip bones
    • Weight is transferred from the axial skeleton to the ilia and then to the femurs during standing and to the ischial tuberosities during sitting. As long as tight apposition is maintained between the articular surfaces, the sacroiliac joints remain stable
    • Is covered by cartilage and is supported by the anterior, posterior, and interosseous sacroiliac ligaments

    anterior sacroiliac ligament

    interosseous sacroiliac ligaments

    posterior sacroiliac ligaments

    • The anterior part of the fibrous capsule of the synovial part of the joint
    • Lying deep between the tuberosities of the sacrum and ilium and occupying an area of approximately 10 cm 2 are the primary structures involved in transferring the weight of the upper body from the axial skeleton to the two ilia of the appendicular skeleton
    • The posterior external continuation of the same mass of fibrous tissue
    • Because the fibers of the interosseous and posterior sacroiliac ligaments run obliquely upward and outward from the sacrum, the axial weight pushing down on the sacrum actually pulls the ilia inward (medially) so that they compress the sacrum between them, locking the irregular but congruent surfaces of the sacroiliac joints together. The iliolumbar ligaments are accessory ligaments to this mechanism
    • Inferiorly, the posterior sacroiliac ligaments are joined by fibers extending from the posterior margin of the ilium (between the posterior superior and posterior inferior iliac spines) and the base of the coccyx to form the sacrotuberous ligament. This massive ligament thus passes from the posterior ilium and lateral sacrum and coccyx to the ischial tuberosity, transforming the sciatic notch of the hip bone into a large sciatic foramen.
    • The sacrospinous ligament , passing from lateral sacrum and coccyx to the ischial spine, further subdivides this foramen into greater lesser sciatic foramina and
    • Is a cartilaginous joint between the sacrum and coccyx, reinforced by the anterior, posterior, and lateral sacrococcygeal ligaments
    • The anterior and posterior sacrococcygeal ligaments are long strands that reinforce the joint, much like the anterior and posterior longitudinal ligaments do for the superior vertebrae

    Posterolateral Wall and Roof

    What are its bony and musculoligamentous constituents and deswcribe them?

    Where does the piriformis muscles arise from?

    Posterior pelvic wall consists of a bony wall and roof in the midline (formed by the sacrum and coccyx) and musculoligamentous posterolateral walls, formed by the ligaments associated with the sacroiliac joints and piriformis muscles . The ligaments include the anterior sacroiliac, sacrospinous, and sacrotuberous ligaments.

    The piriformis muscles arise from the superior sacrum, lateral to its pelvic foramina . The muscles pass laterally, leaving the lesser pelvis through the greater sciatic foramen to attach to the superior border of the greater trochanter of the femur. These muscles occupy much of the greater sciatic foramen, forming the posterolateral walls of the pelvic cavity.Immediately deep (anteromedial) to these muscles (often embedded in the fleshy fibers) are the nerves of the sacral plexus . A gap at the inferior border of the piriformis allows passage of neurovascular structures between the pelvis and the lower limb (gluteal region).

    What are its constituents?

    • Formed by the bowl- or funnel-shaped pelvic diaphragm , which consists of the coccygeus and levator ani muscles and the fascias (L. fasciae ) covering the superior and inferior aspects of these muscles.
    • The pelvic diaphragm separates the pelvic cavity from the perineum within the lesser pelvis.
    • The pelvic diaphragm stretches between the anterior, the lateral, and the posterior walls of the lesser pelvis, giving it the appearance of a hammock suspended from these attachments, closing much of the ring of the pelvic girdle

    arise from the lateral aspects of the inferior sacrum and coccyx, their fleshy fibers underlying the deep surface of the sacrospinous ligament

    The levator ani (a broad muscular sheet) is the larger and more important part of the pelvic floor. It is attached to the bodies of the pubic bones anteriorly, to the ischial spines posteriorly, and to a thickening in the obturator fascia (the tendinous arch of the levator ani ) between the two bony sites on each side.

    An anterior gap between the medial borders of the levator ani muscles of each side of the urogenital hiatus gives passage to the urethra and, in females, the vagina.

    Levator ani forms a dynamic floor for supporting the abdominopelvic viscera. It is tonically contracted most of the time to support the abdominopelvic viscera and to assist in maintaining urinary and fecal continence. It is actively contracted during activities such as forced expiration, coughing, sneezing, vomiting, and fixation of the trunk during strong movements of the upper limbs (e.g., when lifting heavy objects), primarily to increase support of the viscera during periods of increased intra-abdominal pressure (resisting forces that would push it through the pelvic outlet), and perhaps secondarily to contribute to the increased pressure (to aid expulsion). Penetrated centrally by the anal canal, the levator ani is funnel shaped, with the U-shaped puborectalis looping around the funnel spout, its tonic contraction bends it anteriorly.

    The levator ani consists of three parts, designated according to the attachment and course of its fiber:

    Puborectalis: the thicker, narrower, medial part of the levator ani, consisting of muscle fibers that are continuous between the posterior aspects of the right and left pubic bodies. It forms a U-shaped muscular sling (puborectal sling) that passes posterior to the anorectal junction, bounding the urogenital hiatus. This part plays a major role in maintaining fecal continence

    Pubococcygeus: the wider but thinner intermediate part of the levator ani, which arises lateral to the puborectalis from the posterior aspect of the body of the pubis and anterior tendinous arch.It passes posteriorly in a nearly horizontal plane its lateral fibers attach to the coccyx and its medial fibers merge with those of the contralateral muscle to form a fibrous raphe or tendinous plate, part of the anococcygeal body or ligament between the anus and the coccyx (often referred to clinically as the levator plate).

    Iliococcygeus: the posterolateral part of the levator ani, which arises from the posterior tendinous arch and ischial spine. It is thin and often poorly developed (aponeurotic) and also blends with the anococcygeal body posteriorly

    Ovaries and uterine tubes

    Only the superior and superolateral surfaces of plevic viscrea are covered.

    Only the uterine tubes (except for their ostia, which are open) are intraperitoneal and suspended by a mesentery. The ovaries, although suspended in the peritoneal cavity by a mesentery, are not covered with glistening peritoneum instead a special, relatively-dull epithelium of cuboidal cells covers them.

    The median rectouterine pouch is often described as the being inferiormost extent of the peritoneal cavity in the female, but often its lateral extensions on each side of the rectum, the pararectal fossae , are deeper

    • Consists of two layers of peritoneum , extends from the lateral margin of the uterus to the lateral pelvic wall, and serves to hold the uterus in position.
    • Contains the uterine tube, uterine vessels, round ligament of the uterus, ovarian ligament, ureter (lower part), uterovaginal nerve plexus, and lymphatic vessels.
    • Does not contain the ovary but gives attachment to the ovary through the mesovarium.
    • Has a posterior layer that curves from the isthmus of the uterus (the rectouterine fold ) to the posterior wall of the pelvis alongside the rectum.

    The membranous parietal and visceral layers become continuous where the organs penetrate the pelvic floor .

    Here the parietal fascia thickens, forming the tendinous arch of pelvic fascia , a continuous bilateral band running from the pubis to the sacrum along the pelvic floor adjacent to the viscera.

    The anteriormost part of this tendinous arch ( puboprostatic ligament in males pubovesical ligament in females) connects the prostate to the pubis in the male or the fundus (base) of the bladder to the pubis in the female.

    The posteriormost part of the band runs as the sacrogenital ligaments from the sacrum around the side of the rectum to attach to the prostate in the male or the vagina in the female.

    • Is attached to the uterus in front of and below the attachment of the uterine tube and represents the remains of the lower part of the gubernaculum.
    • Runs within the layers of the broad ligament, contains smooth muscle fibers, and holds the fundus of the uterus forward, keeping the uterus anteverted and anteflexed.
    • Enters the inguinal canal at the deep inguinal ring, emerges from the superficial inguinal ring, and becomes lost in the subcutaneous tissue of the labium majus.

    Suspensory ligament of the ovary

    Lateral or transverse cervical (cardinal or Mackenrodt's) ligaments of the uterus

    Is a fibromuscular cord that extends from the ovary to the uterus below the uterine tube, running within the layers of the broad ligament

    Is a band of peritoneum that extends upward from the ovary to the pelvic wall and transmits the ovarian vessels, nerves, and lymphatics.

    Are fibromuscular condensations of pelvic fascia from the cervix and the vagina to the pelvic walls, extend laterally below the base of the broad ligament, and support the uterus.

    Pubovesical (female) or puboprostatic (male) ligaments

    Inferior pubic (arcuate pubic) ligament

    The origin of the obturator artery is variable usually it arises close to the origin of the umbilical artery, where it is crossed by the ureter

    The obturator artery courses anteriorly along the pelvic wall and leaves the pelvic cavity via the obturator canal. Together with the obturator nerve, above, and obturator vein, below, it enters and supplies the adductor region of the thigh.

    • larger in males than in females
    • courses inferiorly from its origin in the anterior trunk and leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle. In association with the pudendal nerve on its medial side, the vessel passes laterally to the ischial spine and then through the lesser sciatic foramen to enter the perineum. The internal pudendal artery is the main artery of the perineum. Among the structures it supplies are the erectile tissues of the clitoris and the penis.

    umbilical artery

    superior vesical artery

    inferior vesical artery

    middle rectal artery

    obturator artery

    internal pudendal artery

    inferior gluteal artery

    uterine artery

    The various plexuses within the lesser pelvis (rectal, vesical, prostatic, uterine, and vaginal) unite and are drained mainly by the internal iliac veins, but some of them drain through the superior rectal vein into the inferior mesenteric vein or through lateral sacral veins into the internal vertebral venous plexus

    The internal iliac veins merge with the external iliac veins to form the common iliac veins, which unite at the level of vertebra L4 or L5 to form the inferior vena cava .

    The iliolumbar veins from the iliac fossae of the greater pelvis usually drain into the common iliac veins.

    The superior gluteal veins, the accompanying veins (L. venae comitantes) of the superior gluteal arteries of the gluteal region, are the largest tributaries of the internal iliac veins except during pregnancy, when the uterine veins become larger.

    Testicular veins traverse the greater pelvis as they pass from the deep inguinal ring toward their posterior abdominal terminations, but do not usually drain pelvic structures

    median sacral vein

    median sacral veins coalesce to form a single vein that joins either the left common iliac vein or the junction of the two common iliac veins to form the inferior vena cava
    the ovarian veins follow the course of the corresponding arteries on the left, they join the left renal vein and, on the right, they join the inferior vena cava in the abdomen

    How many lymp nodes are are located in or adjacent to the pelvis

    External iliac lymph nodes

    Internal iliac lymph nodes

    Sacral lymph nodes

    Common iliac lymph nodes

    • The pelvic inlet in women is circular in shape compared with the heart-shaped pelvic inlet in men. The more circular shape is partly caused by the less distinct promontory and broader alae in women.
    • The angle formed by the two arms of the pubic arch is larger in women (80-85°) than it is in men (50-60°).
    • The ischial spines generally do not project as far medially into the pelvic cavity in women as they do in men

    obturator internus

    These contribute to the lateral walls of the pelvic cavity. These muscles originate in the pelvic cavity but attach peripherally to the femur.

    • Arises from the inner surface of the obturator membrane.
    • Has a tendon that passes around the lesser sciatic notch to insert into the medial surface of the greater trochanter of the femur.
    • Is innervated by the nerve to the obturator.
    • Laterally rotates the thigh
    • The obturator internus forms a large part of the anterolateral wall of the pelvic cavity.

    Triangular in shape and originates in the bridges of bone between the four anterior sacral foramina.

    It passes laterally through the greater sciatic foramen, crosses the posterosuperior aspect of the hip joint, and inserts on the greater trochanter of the femur above the insertion of the obturator internus muscle

    This muscle separates the greater sciatic foramen into two regions, one above the muscle and one below. Vessels and nerves coursing between the pelvic cavity and the gluteal region pass through these two region

    Apertures in the pelvic wall

    • the obturator canal
    • the greater sciatic foramen and
    • the lesser sciatic foramen

    The greater sciatic foramen is a major route of communication between the pelvic cavity and the lower limb. It is formed by the greater sciatic notch in the pelvic bone, the sacrotuberous and the sacrospinous ligaments, and the spine of the ischium

    The piriformis muscle passes through the greater sciatic foramen, dividing it into two parts:

    • The superior gluteal nerves and vessels pass through the foramen above the piriformis.
    • Passing through the foramen below the piriformis are the inferior gluteal nerves and vessels, the sciatic nerve, the pudendal nerve, the internal pudendal vessels, the posterior femoral cutaneous nerves, and the nerves to the obturator internus and quadratus femoris muscles

    Is formed by the lesser sciatic notch of the pelvic bone, the ischial spine, the sacrospinous ligament, and the sacrotuberous ligament. The tendon of the obturator internus muscle passes through this foramen to enter the gluteal region of the lower limb

    Because the lesser sciatic foramen is positioned below the attachment of the pelvic floor, it acts as a route of communication between the perineum and the gluteal region. The pudendal nerve and internal pudendal vessels pass between the pelvic cavity (above the pelvic floor) and the perineum (below the pelvic floor), by first passing out of the pelvic cavity through the greater sciatic foramen, then looping around the ischial spine and sacrospinous ligament to pass through the lesser sciatic foramen to enter the perineum.

    • above, with the sigmoid colon at about the level of vertebra SIII and
    • below, with the anal canal as this structure penetrates the pelvic floor and passes through the perineum to end as the anus.

    The rectum has three lateral curvatures the upper and lower curvatures to the right and the middle curvature to the left.

    The lower part of the rectum is expanded to form the rectal ampulla.

    Finally, unlike the colon, the rectum lacks distinct taeniae coli muscles, omental appendices and sacculations (haustra of the colon).

    the terminal parts of the ureters,

    the proximal part of the urethra

    • In women, these fibromuscular bands are termed pubovesical ligaments. Together with the perineal membrane and associated muscles, the levator ani muscles, and the pubic bones, these ligaments help support the bladder.
    • In men, the paired fibromuscular bands are known as puboprostatic ligaments because they blend with the fibrous capsule of the prostate, which surrounds the neck of the bladder and adjacent part of the urethra
    • Develops from the mesonephric ducts and the urogenital sinus.
    • The urethra in men is divided into preprostatic, prostatic, membranous, and spongy parts.The preprostatic part of the urethra is about 1 cm long, extends from the base of the bladder to the prostate, and is associated with a circular cuff of smooth muscle fibers (the internal urethral sphincter). Contraction of this sphincter prevents retrograde movement of semen into the bladder during ejaculation.The prostatic part of the urethra is surrounded by the prostate.The membranous part of the urethra is narrow and passes through the deep perineal pouch.The spongy urethra is surrounded by erectile tissue (the corpus spongiosum) of the penis.
    • In females, the upper part of the urethra develops from the mesonephric ducts, and the lower end forms from the urogenital sinus.
    • a single prostate
    • a pair of seminal vesicles and
    • a pair of bulbourethral glands.
    • Develops retroperitoneally and descends into the scrotum retroperitoneally.
    • Is covered by the tunica albuginea , which lies beneath the visceral layer of the tunica vaginalis.
    • Produces spermatozoa and secretes sex hormones.
    • Is supplied by the testicular artery from the abdominal aorta and is drained by veins of the pampiniform plexus.
    • Has lymph vessels that ascend with the testicular vessels and drain into the lumbar (aortic) nodes lymphatic vessels in the scrotum drain into the superficial inguinal nodes .
    • the efferent ductules, which form an enlarged coiled mass that sits on the posterior superior pole of the testis and forms the head of the epididymis
    • the true epididymis, which is a single, long coiled duct into which the efferent ductules all drain, and which continues inferiorly along the posterolateral margin of the testis as the body of epididymis and enlarges to form the tail of epididymis at the inferior pole of the testis.
    • Long muscular duct that transports spermatozoa from the tail of the epididymis in the scrotum to the ejaculatory duct in the pelvic cavity. It ascends in the scrotum as a component of the spermatic cord and passes through the inguinal canal in the anterior abdominal wall.
    • Between the ureter and ejaculatory duct, the ductus deferens expands to form the ampulla of the ductus deferens. The ejaculatory duct penetrates through the prostate gland to connect with the prostatic urethra
    • Are enclosed by dense endopelvic fascia and are lobulated glandular structures that are diverticula of the ductus deferens.
    • Lie inferior and lateral to the ampullae of the ductus deferens against the fundus (base) of the bladder.
    • Produce the alkaline constituent of the seminal fluid , which contains fructose and choline.
    • Have lower ends that become narrow and form ducts, which join the ampullae of the ductus deferens to form the ejaculatory ducts.
    • an unpaired accessory structure surrounds the urethra in the pelvic cavity and consists chiefly of glandular tissue mixed with smooth muscle and fibrous tissue
    • Lies immediately inferior to the bladder, posterior to the pubic symphysis, and anterior to the rectum
    • Has five lobes: the anterior lobe (or isthmus), which lies in front of the urethra and is devoid of glandular substance the middle (median) lobe , which lies between the urethra and the ejaculatory ducts and is prone to benign hypertrophy obstructing the internal urethral orifice the posterior lobe , which lies behind the urethra and below the ejaculatory ducts, contains glandular tissue, and is prone to carcinomatous transformation and the right and left lateral lobes , which are situated on either side of the urethra and form the main mass of the gland.
    • Secretes a fluid that produces the characteristic odor of semen. This fluid, the secretion from the seminal vesicles and the bulbourethral glands, and the spermatozoa constitute the semen or seminal fluid.
    • Secretes prostate-specific antigen (PSA) , prostaglandins, citric acid and acid phosphatase, and proteolytic enzymes.
    • Has ducts that open into the prostatic sinus , a groove on either side of the urethral crest.
    • Receives the ejaculatory duct , which opens into the urethra on the seminal colliculus just lateral to the blind prostatic utricle.
    • The two pea-size bulbourethral glands (Cowper glands) lie posterolateral to the intermediate part of the urethra, largely embedded within the external urethral sphincter
    • The ducts of the bulbourethral glands pass through the perineal membrane with the intermediate urethra and open through minute apertures into the proximal part of the spongy urethra in the bulb of the penis.
    • Their mucus-like secretion enters the urethra during sexual arousal.
    • an ovary on each side and
    • a uterus, vagina, and clitoris in the midline
    • a pair of accessory glands (the greater vestibular glands)
    • Extend from the uterus to the uterine end of the ovaries and connect the uterine cavity to the peritoneal cavity.
    • Are each subdivided into four parts: the uterine part , the isthmus , the ampulla (the longest and widest part), and the infundibulum (the funnel-shaped termination formed of fimbriae ).
    • Convey the fertilized or unfertilized oocytes to the uterus by ciliary action and muscular contraction, which takes 3 to 4 days.
    • Transport spermatozoa in the opposite direction (toward the eggs) fertilization takes place within the tube, usually in the infundibulum or ampulla. Fertilization is the process beginning with penetration of the secondary oocyte by the sperm and completed by fusion of the male and female pronuclei
    • Is the organ of gestation in which the fertilized oocyte normally becomes embedded and the developing organism grows until its birth.
    • Is normally anteverted (i.e., angle of 90 degrees at the junction of the vagina and cervical canal) and anteflexed (i.e., angle of 160 to 170 degrees at the junction of the cervix and body).
    • Is supported by thepelvic diaphragm the urogenital diaphragm the round, broad, lateral, or transverse cervical (cardinal) ligaments and the pubocervical, sacrocervical, and rectouterine ligaments.
    • Is supplied primarily by the uterine artery and secondarily by the ovarian artery.
    • Has an anterior surface that rests on the posterosuperior surface of the bladder.

    Body:Is the main part of the uterus located inferior to the fundus and superior to the isthmus. The uterine

    cavity is triangular in the coronal section and is continuous with the lumina of the uterine tube and with the internal os

    Isthmus:Is the constricted part of the uterus located between the body and cervix of the uterus. It corresponds to the internal os

    Cervix:Is the inferior narrow part of the uterus that projects into the vagina and divides into the following regions:

    • Extends between the vestibule and the cervix of the uterus.
    • Is located at the lower end of the birth canal.
    • Has a fornix that forms the recess between the cervix and the wall of the vagina.
    • Opens into the vestibule and is partially closed by a membranous crescentic fold, the hymen.
    • Is supported by the levator ani the transverse cervical, pubocervical, and sacrocervical ligaments (upper part) the urogenital diaphragm (middle part) and the perineal body (lower part).
    • Receives blood from the vaginal branches of the uterine artery and of the internal iliac artery.
    • Has lymphatic drainage in two directions: the lymphatics from the upper three fourths drain into the internal iliac nodes, and the lymphatics from the lower one fourth, below the hymen, drain downward to the perineum and thus into the superficial inguinal nodes.
    • The urogenital triangle is associated with the openings of the urinary systems and the reproductive systems and functions to anchor the external genitalia and is found anterior to the line.
    • The anal triangle contains the anus and the external anal sphincter and is found posterior to the line

    How may layers does it have?

    The superficial perineal pouch (compartment) is a potential space between the membranous layer of subcutaneous tissue and the perineal membrane, bounded laterally by the ischiopubic rami

    In males, the deep perineal pouch contains the:

    1.Intermediate part of the urethra , the narrowest part of the male urethra.

    Bipedalism and the lumbo-sacral junction

    Bipedalism requires anatomical changes so that the torso can remain balanced upright for most activities and there is an ability to stride forward with the swinging gait which is characteristically human. This requires the lumbar and cervical spine to be extended in a lordotic configuration so that the axial load of the body is directed down to the ground in a near straight line when standing. The head, specifically the foramen magnum, is balanced vertically over the plane of the hip joints, in males, and the point of contact of the foot with the ground. This has been achieved by pelvic rotation (retroversion) to enable the hips and knees to straighten.

    Anthrapoid apes have a straight spine and the torso weight lies anterior to the centre of gravity, Loading can be brought further back by flexion of the hips and knees, described as ‘Bent Hips/Bent Knees’ (BHBK, gait) is required for an upright stance. This incurs higher energy requirements and a slower gait. Simulation of BHBK walking by humans increases energy consumption by 50%. This is because 80% of energy is conserved by the exchange of potential for kinetic energy by the rising and falling of the centre of gravity.
    The orthograde upright spinal configuration was achieved, through natural selection, by the lordotic and kyphotic curves (below). Lumbar vulnerability occurs when the wedge angle of the IV disc is reduced..

    Lumbar vulnerability origins are dependant on reduction of these angles.

    The angles that determine lordosis have subsequently been extensively studied. Note, in the diagram above, that the upper surface of S1 forms part of both the Sacral horizontal angle and the wedge angle of L5/S1. The tilt of the pelvis therefore modifies L5/S1 angle. Upright sitting effects the configuration and reduces the wedge angles.

    Already mentioned, the origins of lumbar vulnerability show that lordosis developed at two levels of the human spine, cervical and lumbar. Both these spinal levels are where mobile segments meet a solid mass, the skull and the pelvis, and where mechanical spinal pathology mostly occurs and differences are found when comparing LBP patients with healthy patients (Jackson, 1994). Cyriax wrote in 1946 that “the spinal joints subject to internal derangement are the 4 th , 6 th & 7 th cervical and the 4 th & 5 th lumbar”. Cyriax also recognised that the lordotic wedging of the Inter Vertebral Discs (IVD) have an important function in protecting the discs (Harrison DD 1998) and is compromised by some sitting positions.

    Natural Selection developed an upright (orthograde) posture which results in :-

    • Lordotic changes to the lumbar spine to avoid walking with bent hips & knees (BHBK). See below⟶
    • An increase of the IV Disk wedge angle. This confers a degree of protection from NP retropulsion.
    • Rotation of the pelvic iliac blades for muscles to change from being extensors to abductors ensure pelvic stability.
    • Shortening of the ilium.
    • Relative reduction of the size of the birth canal.

    The early hominids, such as Homo erectus, had a brain of 900 cc. and its primitive variant, of 1.8 MYA, found at the Dmanisi (Georgia) site was only 650-780cc. These were probably the earliest hominids outside of Africa (Lordkipanidze, 2005). H. sapiens, with a volume of about 1300 cc appeared about 130,000 years ago according to the previous ‘out of Africa’ theory’ (Stringer 1970).

    Bipedal rats and others

    Hominids are the only known creatures which are truly bipedal and able to adopt our swinging gait apart possibly wingless birds, such as the ostrich, which are evolved from bipedal dinosaurs. The upright posture occurs in other animals but is usually for short periods and an examination of the skeleton, for example in the penguin, shows a different arrangement with only an analogous appearance of bipedalism. Performing Japanese monkeys (Macaca fuscata). can be trained to adopt an upright posture resulting in lumbar lordosis and bipedalism. Over time some bone remodelling occurs. However energy expenditure is higher than when plantigrade and they revert to this posture when retired from performing (Nakatsukas 2004). Slijper, in 1942, gave a detailed account of the changes in the skeleton of a phocomelic goat that had been born without forelegs. The spine and pelvis had been remodeled with changes suggestive of those found in bipedal animals.

    Rats have been shown (Cassidy 1968) to adopt a bipedal stance and gait if their forelegs are amputated at birth. Their ability to function is remarkable. Their posture and locomotion are surprisingly similar to that of humans and provides the nearest animal model to the human bio-mechanical condition at the lumbar spine. The lumbar spine adapts by becoming lordotic and approximates to that of the human spine and there are changes in the muscles acting around the pelvis. It can be shown that there is increased axial loading on the lumbar spine and a high proportion of these rats develop back disorders which are usually, almost uniquely, only found in humans. These include degenerative changes, disc protrusion, facet joint degeneration and spinal stenosis.