The pelvis

Chapter 11 The pelvis



Chapter contents



Different pelvic types


Pelvic architecture











Gait and the pelvis


Therapeutic considerations



Pelvic problems and the low back






Screening









Testing and treating pelvic, sacral, iliac and sacroiliac dysfunctions








Standing pelvic assessments










Seated pelvic assessments



Supine pelvic assessments and treatment protocols















Prone pelvic assessment and SI treatment protocols












Muscles of the pelvis













































Functional adaptations create the structural features of the pelvis, which has locomotion and support as primary purposes in both genders, and that in the female specifically includes parturition. The pelvis of the male and the female are, therefore, distinctly different and provide marked skeletal variations.


A partial list of pelvic differences related to gender includes the following.





Pelvic architecture


The pelvis is composed of two innominate bones (each made up of an ilium, ischium and pubis), with the sacrum wedged between the ilia posteriorly. The ilium, ischium and pubis have cartilaginous connections in the young but fuse to become one bone by adult life. (Fig. 11.1A/B)



Each innominate bone articulates with its pair anteriorly at the symphysis pubis, thereby forming the pelvic girdle. On the lateral surface of each innominate a cup-shaped, deep depression forms the acetabulum for articulation with the femoral head. The acetabulum comprises the junction of the ilium, ischium and the pubic bones and its articulation with the femur constitutes a true ball and socket joint.




Pregnancy and the pelvis


The ligaments of the pelvis relax during pregnancy, making the joints they serve flexible for expansion and often creating instability in the process. The relaxation of previously stable structures increases the potential for dysfunction and Gray’s anatomy (2005, p. 1439) reports that:



Note: Form and force closure mechanisms for the SI joint are discussed fully later in this chapter.


Levangie & Norkin (2005) discuss the influences of relaxin, a hormone produced during pregnancy that is thought to activate the collagenolytic system. This system alters the ground substance by increasing its water content and decreasing viscosity and also regulates new collagen formation.


The action of relaxin is to decrease the intrinsic strength and the rigidity of collagen and is thought to be responsible for the softening of the ligaments supporting the [sacroiliac joints] and the symphysis pubis. Consequently, the joints become more mobile and less stable, and the likelihood of injury to these joints is increased. The combination of loosened posterior ligaments and an anterior weight shift caused by a heavy uterus may allow excessive movement of the ilia on the sacrum and result in stretching of the SIJ capsules.


Cyriax (1982) states that relaxin is present for up to 3 months after pregnancy. In the authors’ opinion, this is the ideal time to assess and deal with possible displacement of the pelvic bones that may have occurred as a result of pregnancy and/or labor. If possible, correction of such situations should take place before the depletion of relaxin firms the ligaments with the bones in inappropriate positions.


Lee (2004) reports that:



The type of stabilizing belt Lee suggests is worn just above the greater trochanters in order to augment sacroiliac form closure mechanisms ‘until such time as the connective tissue tightens and rehabilitation for force closure mechanisms is instituted’. SI rehabilitation is discussed later in this chapter.



The innominates


As mentioned previously, each innominate is formed from three component bones, the ilium, ischium and pubic bone, and these elements can be described individually (Figs. 11.2 A/B).




The ilium (Fig. 11.3)










The symphysis pubis




According to Gray’s anatomy (2005): ‘Angulation, rotation and displacement are possible but slight…Some separation is said to occur late in gestation and during childbirth’. Despite Gray’s suggesting that ‘possible but slight’ displacement can occur at the symphysis, osteopathic and chiropractic clinical experience contradicts this apparent minimizing of the potential for pubic dysfunction. Pubic dysfunction patterns, and suggested treatments, are described on p. 334 (Greenman 1996, Ward 1997).



The sacrum (Figs. 11.6 A/B)




The female sacrum is shorter and wider than the male’s, as a rule (as is the pelvic cavity – see notes on pelvic classifications on p. 301).


The sacrum, a triangular fusion of five vertebrae, is wedged between the innominate bones to form the posterosuperior wall of the pelvic bowl.


The caudal end of the sacrum (the apex) articulates with the coccyx while the flat cephalad aspect (the base) articulates with the 5th lumbar vertebrae at the sacrovertebral angle.


The dorsal surface of the sacrum is convex and the ventral surface concave.


The sacral base is wide transversely with an anteriorly projecting edge, the sacral promontory.


The sacral foramen is triangular in shape and caudally is known as the sacral hiatus.


The superior, concave-shaped, articular processes of the sacrum project cephalad, articulating with the inferior articular processes of the 5th lumbar vertebra.


Modified transverse processes and costal elements fuse together, and to the rest of the modified vertebral structure, to form the sacral ala or lateral mass.


The ventral surface of the sacrum is usually vertically and transversely concave.


The four pairs of sacral foramina have access to the sacral canal via intervertebral foramina, through which the ventral rami of the upper four sacral nerves pass on the ventral surface.


Lateral to the foramina, costal elements merge and, together with the transverse processes (also known as the costal elements), form the lateral aspect of the sacrum.


The dorsal surface of the sacrum has a sacral ‘crest’ with either three or four spinal tubercles, formed from fused sacral spines.


Inferior to the lowest spinal tubercle is the sacral hiatus formed by the failure of the 5th sacral segment’s laminae to meet medially, so exposing the dorsal surface of the 5th sacral vertebral body.


Fused laminae lie alongside the sacral tubercles and lateral to these are the dorsal sacral foramina (which lead to the sacral canal) through which run the dorsal rami of the sacral spinal nerves.


Medial to the foramina runs the intermediate sacral crest, composed of fused sacral articular processes, the lowest pair (5th) of which is not fused and projects caudally to form the sacral cornua on each side of the sacral hiatus.


The sacral cornua links with the coccygeal cornua by means of the intercornual ligaments.


The lateral surface of the sacrum is formed from fusion of the vertebral transverse processes and costal elements.


The inferior half of the lateral surface is L-shaped and broad (auricular surface) and articulates with the ilium (see p. 311, sacroiliac joint).


Posterior to the auricular surface is a rough area where ligamentous attachments occur (see later in this chapter).


The sacral apex is formed from the inferior aspect of the 5th sacral vertebral body and has an oval facet that articulates with the coccyx.


The sacral canal, as discussed, forms from fused sacral vertebral foramina, with the upper aspect of its triangular opening pointing cranially when the individual is in a standing position.


The cauda equina, the filum terminale and the spinal meninges run through the sacral canal.


The lateral walls of the canal open to the sacral vertebral foramina while inferiorly the canal opens at the sacral hiatus.


The filum terminale (which attaches to the tip of the coccyx) exits from the sacral hiatus (as do the 5th sacral spinal nerves).


Attaching to the ventral and dorsal surfaces of the first vertebral sacral body are terminal fibers of anterior and posterior longitudinal ligaments. The lowest pair of ligamentum flava attach to the upper laminar borders.


The ala or lateral mass is smooth superiorly (covered by psoas major) and laterally rough where the iliolumbar ligament attaches. Iliacus attaches to the anterolateral aspect of this area.


The sacrum’s pelvic surface provides attachments for piriformis muscles.


Running anterior to piriformis, having emerged from the pelvic foramina, are the first three sacral ventral rami.


The sympathetic trunks and the median sacral vessels descend medial to the foramina, directly in contact with bony surfaces.


Lateral sacral vessels descend lateral to the foramina, also in touch with the bony surface.


The ventral surface of the upper sacral segments is covered by parietal peritoneum and is crossed by the attachment of the sigmoid mesocolon.


The rectum is directly in contact with the pelvic surfaces of the 3rd, 4th and 5th sacral vertebrae.


Erector spinae attach to the dorsal sacral surface, overlying multifidus, which also attaches to the sacrum.


The upper three sacral spinal dorsal rami penetrate these muscles as they emerge from the dorsal foramina.


The auricular surface is covered by cartilage and has elevations cranially and caudally. Posterior to the auricular surface are depressions and roughened attachment sites for interosseous sacroiliac ligaments.


Inferior to the auricular surface are a cluster of attachment sites for gluteus maximus and coccygeus as well as the sacrotuberous and sacrospinous ligaments.







Nutation


The movement of the sacrum between the ilia involves a nodding motion, known as nutation, which creates an anterior motion of the sacral promontory. Counternutation is the return to the neutral start position from a nutated position as well as a posterior motion of the sacral promontory.


Bilateral sacral nutation and counternutation movements occur around a coronal axis within the interosseous ligament. Unilateral sacral nutation takes place when the lower extremity is extended. There is also a constant degree of alternating (muscularly) ‘braced’ nutation in the standing position (Dorman 1997). Some muscular influences on sacroiliac function are discussed later in this chapter.


Figures 11.8 and 11.9 illustrate clearly the way in which the SI joint allows a gliding action of the sacrum to occur inferiorly (caudally) along the short arm and posteriorly along the long arm of the joint during nutation; during counternutation the sacrum glides anteriorly on the long-arm surface and superiorly (cephalad) along the short arm. The total degree of movement that occurs in either nutation or counternutation does not exceed 2 mm, but is palpable (see palpation tests later in this chapter). Snijders et al (1997) report that multifidus and levator ani act as a force couple, to help in control of the sacral nutation/counternutation processes.






The coccyx




The coccyx is composed of three, four (most commonly) or five fused, rudimentary vertebrae. The first coccygeal vertebral body forms its upper surface, or base, and articulates via an oval facet with the sacral apex.


Dorsolaterally to the facet lie two coccygeal cornua, which articulate with the sacral cornua superiorly.


A thin, fibrocartilagenous disc, somewhat thinner laterally, lies between the surfaces of the coccyx and sacrum.


Rudimentary transverse processes project superolaterally, which sometimes articulate and sometimes fuse with the inferolateral sacral angle, to complete the 5th sacral foramina.


The 2nd to 4th coccygeal segments become progressively smaller, described by Gray’s anatomy (2005) as ‘mere fused nodules’.


The levator ani and coccygeus muscles attach to the pelvic surface laterally.


The ventral sacrococcygeal ligament attaches ventrally to the 1st and sometimes 2nd coccygeal bodies, as well as to the cornua.


Between the 5th sacral body and the cornua an intervertebral foramen allows passage of the 5th sacral spinal nerve.


The dorsal surface of the coccyx has attachments for gluteus maximus, sphincter ani externus (at the very tip) and the deep and superficial dorsal sacrococcygeal ligaments.


The filum terminale lies between the deep and superficial dorsal sacrococcygeal ligaments, merges with them and to the dorsum of the 1st coccygeal segment. This filament therefore represents a direct attachment of the meninges of the brain, via the spinal dura, to the coccyx. Goodheart (1985) has described a positional release method involving the coccyx and the filum terminale. The objectives include easing spinal and pelvic dysfunctions relating to hypothesized dural restrictions (see Box 11.1).



Box 11.1 Goodheart’s filum terminale (coccygeal) lift technique


Goodheart (1985) has described a method that seems to rely on the crowding, or slackening, of spinal, dural tissues with the coccyx being used as the means of achieving this. Good clinical results in terms of improved function and release of hypertonicity in local areas, as well as those some distance from the point of application, are claimed. Goodheart’s term for this is a ‘filum terminale cephalad lift’.


Goodheart (1985) and Walther (1988) report that there is frequently a dramatic lengthening of the spinal column after application of this coccygeal lift procedure, with Goodheart mentioning specifically that, in good health, there should be no difference greater than about 1 inch in the measured length of the spinal column sitting, standing and lying, using a tapeless measure, which is rolled along the length of the spine.


Goodheart (1984) states:



Improvements in pelvic, spinal and cervical function have been reported (Goodheart 1985, Walther 1988) following use of the coccygeal lift.


As in all positional release methods, tender areas are used as the means of monitoring the lift of the coccyx designed to produce the effects Goodheart describes. The tender areas employed are located in the neck flexor or extensor muscles.


One of the authors (LC) has found the following version of the coccygeal lift (there are prone position variations) to be effective. Note that the application of this method is contraindicated if there is any inflammatory process in the coccygeal region. The method is unlikely to be successful (and could prove uncomfortable) if there has been a previous fracture of the coccyx, altering its normal contours, to an ‘L’ shape, for example.



Method




The patient is sidelying and an area of particular sensitivity to pressure is located in the cervical spinal area.


The patient uses his own digital pressure to monitor the pain once the practitioner has identified it. A score of ‘10’ is ascribed to the tender point and the objective is for this to reduce by at least 70% during the procedure.


The practitioner stands at upper thigh level, behind the sidelying patient, facing the side of the table.


Using the lateral aspect of her cephalad hand (which should be relaxed and not tense throughout the procedure) she achieves contact along the length of the coccyx as she tucks her cephalad elbow against her hip/abdomen area.


The force required to move the coccyx toward the head is applied by the practitioner leaning into the hand contact, not by any arm or hand effort.


This application of pressure is not a push on the coccyx but a slowly applied easing of it toward the head and should cause no pain in the coccygeal region if introduced gently but firmly.


Simultaneously the caudad hand holds the ASIS area in order to stabilize the anterior pelvis and so be able to introduce fine tuning of its position during the ‘lift’, in order to reduce the reported sensitivity score.


As in positional release methods, the patient reports on the changes in palpated pain levels until a 70% reduction is achieved.


This position is held for 90 seconds after which reevaluation of dysfunctional structures is performed.



Ligaments of the pelvis


The sacroiliac (SI) joint is supported by ligaments ventrally dorsally and interosseously, as follows.




The interosseous SI ligament


This vast connection is the main bonding structure between the sacrum and the ilium, filling much of the space posterosuperior to the joint. Covering it superficially is the dorsal SI ligament (below). Gray’s anatomy (2005, p. 1439) describes this as ‘the major bond between the [sacrum and ilia], filling the irregular space posterior superior to the joint’. It is the largest typical syndesmosis in the body (a syndesmosis is a fibrous articulation in which the bony surfaces are held together by interosseous ligaments). Bogduk (2005) regards this structure as ‘the most important ligament of the sacroiliac joint’, the main function of which is to bind the ilium strongly to the sacrum.




The sacrotuberous ligament


The sacrotuberous ligament is really a vertebropelvic ligament although it has, via its connections, profound influence over the SI joint. Both it and the sacrospinous ligament (see below) reduce the opportunity for the sacrum to tilt (nutate), by holding it firmly to the ischium (Bogduk 2005).


The ligament is attached at its cephalad end to the posterior superior iliac spine, blending with the dorsal SI ligaments, the lower sacrum and the coccyx, from where it runs via a thick narrow band, which widens caudally as it attaches to the medial aspect of the ischial tuberosity. From there it spreads toward a merging with the fascial sheath of the internal pudendal nerves and vessels. The posterior surface of the sacrotuberous ligament hosts the attachment of the gluteus maximus, while the superficial lower fibers are joined by the tendon of biceps femoris.


Gray’s (1995, p. 668) notes:



The ligament is penetrated by the coccygeal branches of the inferior gluteal artery, the perforating cutaneous nerve and filaments of the coccygeal plexus (Gray’s anatomy 2005)


The clinical significance of these attachments warrants emphasis. For example, as Van Wingerden et al (1997) state:



Such considerations should be kept in mind when SI joint dysfunction or persistent hamstring tightness is noted, as there would be little benefit in interfering with such a protective mechanism by overenthusiastic treatment of a hamstring. Conversely, treatment of the hamstrings should be considered when the lumbar region, SIJ and or sacrotuberous ligament stabilization can be produced but is inefficient.


Also relevant is the knowledge that an active trigger point in biceps femoris may modify its own tone (Simons et al 1999) and thereby influence SI joint stability (i.e. the muscle would have increased tone but may well be weaker than is appropriate, causing imbalances). This highlights the need for a trigger point search in muscles associated with dysfunctional joints. The eventual course of therapeutic action may or may not involve deactivation of a trigger point in such a setting. See the discussion on trigger points and gluteus weakness on p. 365.




The sciatic foramina


There are two sciatic foramina, the greater and the lesser on each side. The greater sciatic foramen has as its anterosuperior margin the greater sciatic notch, with the sacrotuberous ligament forming its posterior boundary and the ischial spine and sacrospinous ligament providing its inferior borders. The piriformis muscle passes through it as do the superior gluteal vessels and nerves, which leave the pelvis via this route. Below the piriformis, a number of additional structures exit the pelvis via the greater foramen, including the sciatic nerve (usually), inferior pudendal nerve and vessels, inferior gluteal nerve and vessels, posterior femoral cutaneous nerves and the nerves to obturator internus and quadratus femoris (Heinking et al 1997).


The lesser sciatic foramen has as its boundaries the ischial body anteriorly, the ischial spine and the sacrospinous ligament superiorly and the sacrotuberous ligament posteriorly. The tendon and nerve of obturator internus as well as the pudendal nerve and vessels pass through the foramen.


Note: Piriformis is a postural muscle, which will shorten if stressed (Janda 1983). The effect of shortening is to increase its diameter and, because of its location, this allows for direct pressure to be exerted on the sciatic nerve within the foramen, since they pass through it together. After exiting the foramen, the nerve passes under the piriformis in 85% of people. However, in the other 15% the sciatic nerve (or part of it) passes through the muscle so that contraction, spasm, or contractures could produce direct muscular entrapment of the nerve (Beaton & Anson 1938, Te Poorten 1969, Travell & Simons 1992). A diagnosis of piriformis syndrome might be made for either foraminal or muscular belly entrapment (Fig. 11.11).



In addition, the pudendal nerve and the blood vessels of the internal iliac artery, as well as common perineal nerves, posterior femoral cutaneous nerve and nerves of the hip rotators, can all be affected in a similar manner (Janda 1996). If the pudendal nerve and blood vessels, which pass through the greater sciatic foramen and reenter the pelvis via the lesser sciatic foramen, are compressed because of piriformis contractures, impaired circulation to the genitalia will occur (in either gender). Since external rotation of the hips is required for coitus by women, pain noted during this act, as well as impotence in men, could relate to impaired circulation induced by piriformis dysfunction within the sciatic foramen.


The next focus of this chapter is the sacroiliac joints – a major source of pain and dysfunction. Before looking at this remarkable structure, we suggest that the subjects of pain in general, and pain as it relates to the pelvis in particular, as discussed in Box 11.2 on p. 317, should be read as the definitions are relevant in the remaining discussions.



Box 11.2 Definitions of pelvic pain




Pelvic girdle pain (PGP)


The pelvic girdle is considered to be the bony ring formed by the hip bones and the sacrum, to which the lower limbs are attached. A definition has been proposed of pelvic girdle pain (and dysfunction), that aims to distinguish this from pelvic pain and dysfunction relating to gynecological or urological disorders. (Vleeming et al 2008)



In reality, these structural (PGP) and gynecological and/or urological features of pelvic pain frequently overlap, so that the definition above may need to be supplemented by a further definition – that of ‘chronic pelvic pain’ (CPP).


CPP has been defined as follows (Fall et al 2004):



It is clear that this broader CPP definition incorporates the features of PGP, without specifying tissues or locations.


The American College of Gynecologists, also in 2004, proposed the following definition of CPP:



Therefore, when the term chronic pelvic pain (CPP) is used in this text, unless specifically stated to the contrary, this will refer to pain anywhere in the pelvis, arising from, or being referred to part or all of the region that lies inferior to the lumbar spine (although this will be involved at times) and superior to the gluteal folds (although adductors and hamstrings may contribute to it) – whether involving osseous, neurological, ligamentous, or other soft tissues, including the viscera.



The sacroiliac joint


The surfaces of articulation between the sacrum and the ilium are reciprocally irregular, which restricts movement and provides the joint with considerable strength as it transmits weight from the vertebral column and the trunk to the lower limbs. There is an articular joint capsule that attaches close to both articular margins.


With age, in both genders, fibrous adhesions and other changes gradually obliterate the joint. ‘In old age the joint may be completely fibrosed and occasionally even ossified’ (Gray’s anatomy 2005, p. 1438). Clinically, these changes are important as radiographic research has demonstrated that even before age 50, 6% of joints show evidence of a degenerative process (Cohen et al 1967).



SI joint movement


A very small amount of anteroposterior rotation occurs around a transverse axis when the trunk is flexed or extended, with the degree of movement increasing during pregnancy. According to Gray’s anatomy (1995):



Bogduk (2005) explains the essential role of the SI joints.



Indeed, the evidence is that when the SI joint fuses, as it does in some people due to age or disease (ankylosing spondylitis, for example), the sacrum does literally crack, especially if weakened by osteoporosis (Lourie 1982). Bogduk (2005) reports:



The current understanding of the SI joint is therefore that it performs stress absorption functions as forces from above or below are transferred into the pelvic mechanism. These forces are partially absorbed into the enormous and powerful ligamentous support which the joint enjoys and partially into the unique mechanical relationship the sacrum has with the ilia, where an osseous locking device allows transfer of forces into the pelvis as a whole. Bogduk (2005) again succinctly summarizes the way in which the functional needs of the SI joint have been accommodated into its design.


For its longitudinal functions, it will exhibit osseous features that lock it into the pelvic ring. For its anti-torsion functions it will exhibit, in a parasagittal plane, a planar surface that can allow gliding movements, but it will be strongly reinforced by ligaments that both retain the locking mechanism and absorb twisting forces.


These functional needs have been superbly incorporated into the SI joint’s design.



Self-locking mechanisms of the SI joint


Two mechanisms lock the joint physiologically and these are known as ‘form closure’ and ‘force closure’ mechanisms.


Form closure is the state of stability that occurs when the very close-fitting joint surfaces of the SI joint approximate, in order to reduce movement opportunities. The efficiency and degree of form closure will vary with the particular characteristics of the structure (size, shape, age) as well as the level of loading involved. Lee (2004) lists three ways that fit (form) of the sacroiliac joint protect it from shear.



‘All three factors enhance stabilization of the SIJ when compression (force closure) are required to balance the moment of a large external load.’


Force closure refers to the support offered to the SI joint by the ligaments of the area directly, as well as the various sling systems which involve both muscular and ligamentous structures (see discussions within this chapter) (Vleeming et al 2007).


Examples of ‘force closure’ are:




Motor control and force closure


O’Sullivan & Beales (2007) suggest that the motor control system can become dysfunctional in a variety of ways, leading to maladaptation and pain (see Figure 11.12). Maladaptive changes might then in turn lead to reduced force closure (involving a deficit in motor control) or excessive force closure (involving either a deficit, or an increase in motor activation), resulting in a mechanism for ongoing peripheral pain sensitization and leading to chronic pain that involves the sacroiliac and/or other pelvic structures. Additionally the pelvic floor itself may be involved in such adaptations – with the possibility of chronic pelvic pain (CPP) symptoms emerging (O’Sullivan, 2005).



Note: See notes toward the end of this chapter on pelvic floor issues.


A summary of muscular involvements in these processes is outlined below.



Innervation of the SI joint


Bogduk (2005) reports that there is little in the way of authoritative evidence to support various contradictory claims as to the precise innervation of the joint. Lee (2004) reports that there is evidence that posteriorly the SI joint is supplied from the posterior rami of the S1 and S2 spinal nerves (Solonen 1957); that the dorsal SI ligaments (and probably the joint) are supplied from lateral divisions of the dorsal rami of L5, S1, S2 and S3 spinal nerves (Bradlay 1985), while the lateral branches of L5, S1 and S2 dorsal rami form a plexus between the interosseous and dorsal sacroiliac ligaments (Grob 1995). There was contradictory research evidence from Solonen and from Grob as to the ventral neural supply to the SI joint, which apparently varied considerably between different individuals. Lee asserts: ‘The wide distribution of innervation is reflected clinically in the variety of pain patterns reported by patients with SI joint dysfunction’.



Muscles and the SI joint


According to Bogduk (2005) there are no muscles that actively move the SI joints; however, a great many muscles attach powerfully on either the sacrum or the ilia and are therefore capable of strongly influencing the functional adequacy of the pelvis as a whole and of SI joints in particular.


Dorman (1997) suggests that: ‘Judging by their attachments, various muscles are probably involved, directly or indirectly, in force closure of the SIJ’. Indirectly muscles can act on ligaments and fascia (see the discussion regarding the influence of the hamstrings on the sacrotuberous ligament on p. 436 and in Chapter 3).




Slings, units and systems (Fig. 11.13)


Lee (2004) discusses muscular contributions to the stability of the pelvic structures (as well as the lumbar spine and the hip) and points out that there are two muscular systems involved, a local and a global system.



The local system includes:



In the past, four slings (then referred to as systems) were described by Lee (1999) as comprising the second muscle system, these being


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Dec 11, 2016 | Posted by in NEUROLOGY | Comments Off on The pelvis

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