Osteopathy Journals and Research by Darren Chandler

 

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  1. Introduction

    The sacroiliac joint is responsible for many different pain presentations. Clinical testing and the effects of joint manipulation has received mixed reviews.

    A full understanding of the anatomy and mechanics of the sacroiliac joint can give a better understanding of the mechanical injuries affecting the joint as well as the different manipulative and diagnostic procedures used in sacroiliac joint pain management.

    The article is separated into:

    • Review of the structures: capsular, ligamentous, myofascial and neurological.

    • Movements of the sacroiliac joint: movement in health and injury.

    • Mechanisms of sacroiliac joint dysfunction.

    • Entrapment neuropathies in the pelvis causing sacroiliac joint pain.

    • Sacroiliitis.

    • Diagnostic testing for the sacroiliac joint.

    Review of the structures: capsular, ligamentous, myofascial and neurological

    The sacroiliac joint is located between the sacral and iliac articular surfaces. Zou et al (2015) measured the width of the joint space at 2–3-mm which declines with age.

    The joint surface is flat in childhood but then becomes irregular in adulthood. The curves and irregularities are reciprocal e.g. a convexity on the iliac surface is met with a concavity on the sacral surface.

    The joint consists of (1) a syndemosis (fibrous) part and (2) a synovial part.

    (1) Syndemosis (fibrous) part: this lies in the superior two-thirds of the sacroiliac joint parallel to S1-2 and is composed of the interosseous sacroiliac ligaments (Zou et al 2015).

    (2) Synovial part: this lies in the inferior one-third parallel to S3–S4 levels (Zou et al 2015).

    Brun-Rosso et al (2016) found that under vertical loads (e.g. standing) the sacrum rotates around a horizontal axis (nutation) with some accompanied translation movement. This horizontal axis goes through the interosseous ligaments.

    This ligament exerts the greatest strain in restricting movement (Eichenseer et al 2011). If the movement in the superior two thirds of the joint has to be relatively restricted so the interosseous ligament can provide this stable horizontal axis then the movement will be greater farther away from the axis in the inferior one third of the joint.

    This would explain the presence of the synovial part of the joint in the lower third (Zou et al 2015). It would also explain how stiffness in the sacrotuberous and sacrospinous ligament increases the range of motion of the sacrum by pulling on this distal mobile area (Hammer et al 2013).

    The sacrum is covered by hyaline cartilage which is thicker anteriorly than posteriorly in adults. The hyaline cartilage on the ilium is thinner. This cartilage has been proposed to have a mechanical effect on restricting sacroiliac joint movement (Hammer et al 2013).

    Articular capsule

    Both the anterior and posterior sacroiliac joint capsules attach close to both articular margins of the joint.

    (1)   Anterior sacroiliac joint capsule.

    The anterior sacroiliac joint capsule is relatively thin. It relates closely to the nerve fibers of the lumbosacral trunk (L4 and L5 nerve roots) and the nerve bundles of the obturator nerve (Vleeming et al 2012).

    Soft tissues that blend with the anterior sacroiliac joint capsule include:

    • Piriformis (Solonen, 1957 & McCory and Bell 1999).

    • Iliacus: Solonen (1957) claimed that the Iliopsoas muscle partly originates from the anterior sacroiliac joint capsule although the author was probably refering to the Iliacus. More recently Standring (2017) claimed the Iliacus originated from the anterior sacroiliac ligament but not the joint capsule.

    • The sacrospinous ligament (Stout 2010).

    Otsuru et al (2017) found a ureretric entrapment inside the sacroiliac joint.

    (2)   Posterior sacroiliac joint capsule.

    The posterior sacroiliac joint capsule is discontinuous (Fortin et al 1999) and is closely related to the nerves exiting the sacral foramen.

    Ligaments

    (1)    Iliolumbar ligaments.

    The iliolumbar ligaments run from L4 and L5 to the sacrum and ilium. It forms hoods over the L4 and L5 nerve roots that are capable of causing an entrapment neuropathy of these nerves (Vleeming et al 2012). The iliolumbar ligaments blends with the thoracolumbar fascia and anterior sacroiliac joint capsule.

    Mens et al (1999) illustrated the functional relationship of the shared anatomy between the iliolumbar ligament, ilium, and anterior joint capsule. “As the right innominate rotates anteriorly and produces a caudad shift of the pubis the right illiolumbar ligament pulls L4-5 into left rotation and right lateral flexion”.

    (2)    Anterior sacroiliac joint ligament.

    The anterior sacroiliac ligament is a thickening of the anterior-inferior joint capsule. It is particularly well developed near the arcuate line and the posterior inferior iliac spine where it connects S3 to the lateral side of the preauricular sulcus. It is thin elsewhere.

    Solonen (1957) claimed the anterior sacroiliac ligaments were direct continuations of fibers from the Piriformis and iliopsoas (the author is probably referring to Iliacus). He claimed that part of the origin of these muscles originate, in part, from inside the capsule of the sacroiliac joint. 

    McCory and Bell (1999) found there is a fascial origin for the Piriformis arising from the capsule of the sacroiliac joint. As these fibres pass inferiorly rather than laterally it brings the Piriformis in contact with the anterior ligament of the sacroiliac joint and the roots of the 1st to 3rd sacral nerves. The Iliacus has more recently been documented as originating partly from the anterior sacroiliac ligament (Standring 2017) but not the anterior sacroiliac joint capsule as claimed by Solonen (1957).

    (3)    Interosseus sacroiliac ligament (including the short posterior sacroiliac ligament).

    The interosseous sacroiliac ligament is a major bond between the ilium and sacrum forming the syndemosis part of the superior two thirds of the joint.

    Short posterior sacroiliac ligament: extension of the interosseous sacroiliac ligament passing from S1 and S2 to the ilium.

    (4)    Posterior sacroiliac ligament (including the long posterior sacroiliac ligament).

    Lies superficial to the interosseous ligament and blends with the sacrotuberous ligament. Connects the intermediate and lateral sacral crests to the PSIS and the posterior end of the internal lip of the iliac crest.

    Long posterior sacroiliac ligament: extension of the posterior sacroiliac ligament. Fibers extend from S3 and S4 to the PSIS and the posterior end of the internal lip of the iliac crest.

    Between the deeper interosseous ligament and more superficial posterior sacroiliac ligament lies the dorsal rami of the sacral spinal nerves.

    The long posterior sacroiliac ligament can either be penetrated by the sacral rami (McGrath & Zhang 2008) or have the nerves run underneath or over it (Konno et al 2017). There is a wide-ranging variation among fibers of the long posterior sacroiliac ligament being connected to (Vleeming et al 2012):

    • The deep lamina of the posterior lumbar fascia.

    • Aponeurosis of the erector spinae muscle and multifidus muscle.

    • Gluteus Maximus (Barker et al 2014).

    • Blending distally into the sacrotuberous ligament.

    Traditionally lip service has been paid to these attachments of the long posterior sacroiliac ligament but on dissection it must be remembered that these attachments are through the tough dense sheaths of the thoracolumbar fascia (Willard et al 2012).

    (5)    Sacrotuberous ligament.

    Runs from the PSIS, posterior sacroiliac ligaments (with which it is partly blended), lateral sacral crest to the upper coccyx to the ischial tuberosity and ramus.

    Its soft tissue attachments are:

    (a)   Blends with the fascial sheet of the internal pudendal vessels and pudendal nerve.

    (b)   Piriformis (Solonen 1957).

    (c)   Lowest fibers of the Gluteus Maximus.

    (d)   Blends partially with the sacrospinous ligament.

    (e)   Biceps Femoris and semimembranosis (Solonen 1957).

    (f)    Thoracolumbar fascia: between the outer thoracolumbar fascia and inner sacrotuberous ligament a tunnel is formed that nerves from the sacral rami run through (Willard et al 1998).

    Nerves that pierce this ligament are:

    (a)   Nerves from the coccygeal plexus

    (b)   Perforating cutaneous nerve

    (6)    Sacrospinous ligament.

    Extends from the ischial spine to the lateral margins of the sacrum and coccyx anterior to the sacrotuberous ligament.

    The sacrospinous ligament attaches to:

    (a) Sacrotuberous ligament (Standring 2017).

    (b) Anterior sacroiliac joint capsule (Stout 2010).

    (c) Coccygeus muscle: the anterior surface of this ligament is the coccygeus muscle.

    Usually ligaments restrict movement. Hammer et al (2013) found this to be the case with the sacrotuberous and sacrospinous ligaments reducing movement at the acetabulum and the pubic symphysis. However at the sacrum they found increased stiffness in the sacrospinous and sacrotuberous ligaments increased sacral movement. They attributed this to their distal attachments and the relative fixation of the upper part of the sacrum. In other words the stiffness in these ligaments pull on the more flexible lower part of the sacrum. 

    Biomechanics of the sacroiliac ligaments

    Different trunk positions have been shown to place maximum strains on the sacroiliac ligaments (Kim et al 2014):

    Anterior sacroiliac ligament: flexion, extension, torsion and flexion with torsion.

    Interosseous sacroiliac ligament: flexion with torsion.

    Long and short posterior sacroiliac ligament: extension.

    Sacrospinous Ligament: flexion and flexion with torsion.

    Sacrotuberous Ligament: flexion and flexion with torsion.

    Movements of the sacroiliac joint: movement in health and injury

    Sacroiliac joint movements includes (1) movements of the sacrum on the innominate bone and (2) movements of the innominate bone on the sacrum.

    (1) Movements of the sacrum on the innominate bone.

    Goode et al (2008) found movement at the sacroiliac joint in six planes. Three were pivoting around three axes and three were translating along these same three axes. The axes are:

    (a)   Transverse axis (sacral X-axis): courses mediolateral through the left and right PSIS. This permits sacral rotation in a sagittal plane (nutation and counternutation, Forst et al 2006) and translation transversely along this axis.

    (b)   Longitudinal axis (sacral Y-axis): this permits sacral rotation in the horizontal plane and translation superiorly along this axis.

    (c)   Sagittal axis (sacral Z-axis): courses anterior-posterior midway between the anterior superior iliac spines (ASIS). This permits sacral rotation in the coronal plane and translation anteriorly along this axis.

    Ranges of motion:

    (a)   Transverse axis (sacral X-axis): rotation around the axis ranged between −1.1 and 2.2 degrees.  Translation along the axis ranged between −0.3 and 8.0mm.

    (b)   Longitudinal axis (sacral Y-axis): rotation around the axis ranged between −0.8 and 4.0 degrees. Translation along the axis ranged between −0.2 and 7.0mm.

    (c)   Sagittal axis (sacral Z-axis) rotation around the axis ranged between −0.5 and 8.0 degrees. Translation along the axis ranged between −0.3 and 6.0 mm.

    Forst et al (2006) associated lumbosacral extension and flexion with movement of the sacrum around a transverse axis in nutation and counternutation respectively.

    (2) Movements of the innominate bone around the sacrum.

    Innominate ranges of motion has been documented in:

    (a) Rotation around a transverse axis.

    (b) Rotation around a vertical axis.

    (c) Vertical shear along a longitudinal axis.

    (a) Rotation of the innominate around a transverse axis: anterior and posterior rotation.

    • Anterior rotation of the innominate is produced by:

    Hip extension: extension of the hip produces an anterior rotation (Barakatt et al 1996) and moves the innominate away from the sacrum (Stout 2010). Mens et al (1999) contradicted this saying that during hip flexion the innominate rotates anteriorly. This closely allies Kibsgard et al (2017) (refer to posterior innominate rotation).

    Short leg: Coopersten and Lew (2010) found the innominate bone rotates anteriorly on the side of the short leg.

    Inferior vertical shear of the innominate: When standing on a step with one leg the other leg hanging down undergoes anterior rotation of the innominate bone (Mens et al 1999). This relates to Barakatt et al (1996) who found doing the opposite i.e. elevating the leg (as opposed to letting it hang down) posteriorly rotates the innominate bone.

    • Posterior rotation of the innominate is produced by:

    Standing: the forces coming up from the ground along the long axis of the leg runs up through the hip joint and posteriorly rotates the innominate (Hungerford et al 2004).

    Hip flexion: Stout (2010) found on hip flexion the innominate rotates posteriorly, translates caudad down the vertical axis and compresses the sacrum. This finding however was contradicted by Kibsgard et al (2017) who found during an active SLR (unilateral hip flexion) there was greater movement in posterior rotation of the innominate on the contralateral side that wasn’t undergoing hip flexion.

    Superior vertical shear of the innominate: Barakatt et al (1996) found elevating the innominate by either placing a platform under the foot or an ischial tuberosity posteriorly rotates the ipsilateral innominate.

    Long leg: Barakatt et al (1996) findings of an elevated leg posteriorly rotating the innominate was confirmed by Cooperstren and Lew (2009) who performed a literature review on leg length discrepancy and innominate rotation. They found the literature supported a posteriorly rotated innominate on the side of the longer leg.

    Prone hip abduction and external rotation (HABER): this has been shown to posteriorly rotate the ipsilateral innominate (and anteriorly rotate the contralateral innominate) (Bussey et al 2009).

    (b) Rotation of the innominate around a vertical axis.

    Kibsgard (2017) noted when performing an ASLR the innominate bone of the rested leg (the one not being tested) had an inward tilt of 0.3. degs and a posterior rotation of 0.8°.

    The compression and decompression of the sacrum noted by Stout (2010) in posterior and anterior rotation respectively presumably related to rotation around a vertical axis. Whether she defined compression and decompression as an inward tilt (which would cause force closure of the sacroiliac joint) or outward tilt around the sacrum was not specified.

    Bussey and Milosavljevic (2013) investigated movement of the innominate bone around a vertical axis using hip abduction and external rotation (HABER). They found in healthy controls the rotation of the innominate was either reciprocal (e.g. with the right hip in HABER each innominate bone will rotate in opposing directions) or unilateral (e.g. if the right hip is in HABER both innominate bones would rotate to the right and if the left hip is in HABER both innominate bones would rotate to the left).                        

    (c)   Vertical shear of the innominate along a vertical axis.

    Greenman (1986) identified movement of the innominate bone in a cephalad or caudad direction along a vertical axis creating a superior innominate shear (upslip innominate) or inferior innominate shear (downslip innominate). Mens et al (1999) found an inferior vertical shear of the innominate (downslip innominate) anteriorly rotates the innominate bone.

    Mechanisms of sacroiliac joint dysfunction

     Mechanisms for sacroiliac joint dysfunction are:

    1. Mechanical loading: mechanical loading produces an eccentric load that can ‘contort’ the pelvis causing articular and soft tissue strains.

    2. Hormonal changes and an enlarged uterus.

    3. Altered neuromuscular control: altered neuromuscular control to the muscles that support the sacroiliac joint can occur secondary to a sacroiliac joint injury. However altered neuromuscular control to the muscles that support the sacroiliac joint from other causes can cause sacroiliac joint injury by directly force closing the joint (Barker et al 2014).

    Mechanical loading

    The far reaching effects of pelvic mechanics on the soft tissues has been summarised by Adhia et al (2016). They found when you induce an oblique axis by placing the subject in prone hip abuction and external rotation on the right leg (HABER) the following:

    • The right innominate rotates posteriorly and externally rotates.

    • The left innominate rotates anteriorly and internally rotates.

    • At the right sacroiliac joint the sacrum rotates to the left and nutates.

    • At the left sacroiliac joint the sacrum rotates to the left and counternutates.

    • The right short and long posterior sacroiliac ligaments relaxes.

    • The left short and long posterior sacroiliac ligaments tenses.

    • The right anterior sacroiliac, interosseous, sacrotuberous, sacrospinous and iliolumbar ligaments tense.

    • The left anterior sacroiliac, interosseous, sacrotuberous, sacrospinous and iliolumbar ligaments relaxes.

    Adhia et al (2016) refers to a posterior rotation of the innominate causing tension in the ipsilateral iliolumbar ligament which is the opposite to Mens et al (1999) who found anterior rotation of the innominate caused tension in the iliolumbar ligament. However in the model used by Mens et al (1999) this anterior rotation was secondary to a leg hanging off a step where the innominate bone shifts caudad.

    It’s not just in a HABER position that altered axes of motion are produced for the sacroiliac joint. Fortin and Flaco (1997) highlighted how a vertical shear of the innominate from injuries such as landing in mid-stance or ‘missing a step’ can cause complications. The result of this ipsilateral upward shear is that the sacrum no longer rotates around a straight horizontal axis but eccentrically pivots around an oblique axis.

    For example if you missed a step with the right leg the right innominate will shear superiorly along a vertical axis and be higher. If the right innominate is higher the right side of the transverse axis will be higher. If the right side of the transverse axis is higher when the sacrum nutates instead of the sacral base ‘nodding’ directly forwards it will ‘nod’ or nutate around an oblique axis to the right.

    It’s not just the sacrum that moves incorrectly when subject to injury. Hungerford et al (2004) found that posterior rotation of the innominate occurred during weight bearing in healthy subjects. This movement pattern optimises stability of the pelvic girdle during weight bearing. In symptomatic individuals the innominate bone anteriorly rotated during weight bearing. This faulty pattern may indicate abnormal articular function due to altered axis of movement through the pelvis.

    Hormonal changes and an enlarged uterus

    Hormonal changes and an enlarged uterus causes an increased lumbar hyperlordosis, pelvic anteversion, and widening of the pubic symphysis. The sacroiliac joints oppose this rotation causing an increase of mechanical tension of the pelvic ligaments, which eventually results in lower back pain (Sipko et al 2010).

    Altered neuromuscular control

    Subjects with sacroiliac joint pain try to enhance force closure of the sacroiliac joint by faulty motor control of the muscles that stabilise the joint (O’Sullivan et al 2002). Therefore tightness in the myofascial structures associated with sacroiliac joint stabilisation (and compression) may be indicative of a sacroiliac joint dysfunction or intern directly cause it (Barker et al 2014). The myofascial structures that induce force closure of the sacroiliac joint include (Wingerden et al 2004):

    • Gluteus Maxims (Barker et al 2014).

    • Biceps femoris.

    • Latissimus dorsi.

    • Posterior layer of the thoracolumbar fascia.

    • Transverse abdominals and external and internal obliques.

    • Aponeurosis of the erector spinae (including the Multifidus).

    • Pelvic floor (O’Sullivan et al 2002).

    • Diaphragm (O’Sullivan 2002).

    The erector spinae aponeuriosis (with the Multifidus), the biceps femoris, gluteus maximus, oblique and transverse abdominis muscles were shown to have the greatest effect on sacroiliac joint force closure. The latissimus dorsi has the small effect (Wingerden et al 2004).  

    Entrapment neuropathies in the pelvis causing sacroiliac joint pain

    The dorsal sacral rami refers pain mimicking sacroiliac joint pain. The dorsal sacral rami penetrates and can be trapped in the:

    (1) Multifidus.

    (2) Long Posterior Sacroiliac Ligament.

    (3) Between the Sacrotuberous Ligament and Thoracolumbar fascia.

    (4) Gluteus Maximus.

    All these soft tissues cause force closure of the sacroiliac joint. Their anatomy has been discussed in 'review of the structures: capsular, ligamentous, myofascial and neurological' . Their function in stabilising the sacroiliac joint and contributing to its injury is discussed in 'mechanisms of sacroiliac joint dysfunction (altered neuromuscular control)'. 

    What is discussed here is the anatomy of the dorsal sacral rami in reference to entrapment neuropathies in these myofascial and ligamentous structures. This has been shown to mimic sacroiliac joint pain in the long posterior sacroiliac ligament (McGrath and Zhang 2005, Murakami et al 2007) and be at the very least a potential source of double crush in the other tissues.

    Murakami et al (2007) compared the effects of blocking injections into the sacroiliac joint and around the Long Posterior Sacroiliac Ligament in patients with sacroiliac joint pain. 100% got relief by blocking the Long Posterior Sacroiliac Ligament and only 9 out of the 25 patients got relief from the intraarticular injection. Could this relief be due to the anatomy of the Long Posterior Sacroiliac Ligament in trapping the dorsal sacral rami causing sacroiliac joint pain?

    Multifidus

    The Multifidus arises from the spinous process of L5 to as low as the fourth sacral foramen, PSIS and dorsal sacroiliac ligament. The longest fibers of the Multifidus run from the spinous processes of L1 and L2 to the dorsal segment of the iliac crest.

    Along with being tightly adhered to the erector spinae aponeurosis the sacral attachment of the multifidus is also tightly adhered to the medial branches of the sacral dorsal rami. To illustrate how tight this adherence is when the multifidus was removed piecemeal many of these nerves were removed along side with it (Cox & Fortin 2014).

    Long Posterior Sacroiliac Ligament

    The dorsal sacral rami pass either through (McGrath & Zhang 2005), beneath or over (Konno et al 2017) the long posterior sacroiliac ligament (along with minute blood vessels potentially creating ischaemic zones Willard et al 1998). 

    The levels at which the lateral branches of the dorsal sacral rami typically penetrate the Long Posterior Sacroiliac joint Ligament are: 

    S1

    4%

    S2

    96%

    S3

    100%

    S4

    59%

    (McGrath & Zhang 2005)

    Sacrotuberous Ligament 

    The sacral rami run posterior to the sacrotuberous ligament (Standring 2017) through a tunnel created by the sacrotuberous ligament internally and an outer sheath of the thoracolumbar fascia (Willard et al 1998).

    Gluteus Maximus

    The sacral rami run from the sacrotuberous ligament forming loops under the Gluteus Maximus. These nerves then pierce the Gluteus Maximus along a line running from the PSIS to the apex of the coccyx (Standring 2017).

    Sacroiliitis

    Sacroiliitis has been associated with inflammatory changes (Almodovar et al 2014, Fortin et al 1999) as well as changes to the bone (Panwar et al 2017) and joint space (Zou et al 2015).

    The diffuse local and lower extremity pain referred from sacroiliac joint problems has been associated with (1) the joint's innervation and (2) its close association with neighbouring nerve trunks.

    The anterior sacroiliac joint capsule relates closely to the nerve fibers of the lumbosacral trunk (L4 and L5 nerve roots) and the nerve bundles of the obturator nerve (Vleeming et al 2012). The anterior sacroiliac joint capsule being relatively thin allows substances in the joint space to leak out and potentially irritate the lumbosacral trunk (Vleeming et al 2012).

    The dorsal sacroiliac joint capsule is discontinuous (Fortin et al 1999) and is closely related to the nerves exiting the sacral foramen. This discontinuous capsule allows once again for extravastation of joint fluid to potentially irritate the neighbouring nerves.

    Fortin et al (1999) found three pathways between the sacroiliac joint and neural structures. These were:

    (1) Posterior extravastation into the dorsal sacral foramen.

    (2) Superior recess extravastation at the sacral alar level to the L5 epiradicular sheath.

    (3) Ventral extravastation to the lumbosacral plexus.

    Due to the discontinuous nature of the posterior sacroiliac joint capsule the most common pattern of extravastation was posteriorly. Whilst it is not known if this ‘inflammatory leakage’ is a pathological mechanism for neuropathies its potential effects not only directly on the nerves but indirectly by its effects on the connective tissue could be a potential mechanism for neuropathies.

    Four zones of the sacroiliac joint have been identified accounting for different symptoms when stimulated (Kurosawa et al 2015). These zones are:

    Zone 1 (upper section): pain was referred around the PSIS.

    Zone 2 (middle section): pain was referred to the middle buttock.

    Zone  3: (lower section): pain was referred to the lower buttock.

    Zone 0 (cranial portion of the ilium outside the SIJ): pain was referred mainly to the upper buttock along the iliac crest.

    All subjects complained of groin pain, which was slightly relieved by lidocaine injection into zones 1 and 0.

    Diagnostic testing for the sacroiliac joint

    Diagnostic testing for the sacroiliac joint has received mixed reviews due to the complexities of the joint and its soft tissues.

    The sacroiliac joint tests associated with stretching the different sacroiliac ligaments are (Kim et al 2014): 

    (a) Anterior sacroiliac ligament: thigh thrust test and Gaenslens test.

    (b) Interosseous sacroiliac ligament: compression test, distraction and sacral apex pressure test, thigh thrust test, Patrick FAbER and Gaenslens test.

    (c) Long posterior sacroiliac ligament: Gaenslens test (minimal).

    (d) Short posterior sacroiliac ligament: thigh thrust test, Patrick FAbER and Gaenslens test.

    (e) Sacrospinous ligament: Gaenslens tests (minimal).

    (f) Sacrotuberous ligament: Gaenslens test (minimal).

    van de Wurrf et al (2000) reviewed clinical testing for the sacroiliac joint and found the two most reliable tests were Gaenslens and the thigh thrust test.

    This was later confirmed by Arnbak et al (2017) who advocated these two tests but also a pain provocation sign when palpating the long posterior sacroiliac ligament. However these authors only found these tests accurate in men.

    Werner et al (2013) found a 100% accuracy when performing a PSIS distraction test. This was performed as a pain provocation test where a punctual force was applied to the PSIS in a medial to lateral direction. The rationale for the high degree of sensitivity was the relationship of the sacral rami to the long posterior sacroiliac ligament. 

    Active straight leg raising test (ASLR) has also been shown to be a more reliable test for the diagnosis of sacroiliac joint pain. However in this test there has been shown to be a greater posterior rotation of the innominate on the side not being tested (Kibsgard et al 2017). As a whole, the research papers tend to point not so much towards the shearing movement of the sacroiliac joint during this test but the altered neuromuscular control in the muscles trying to force close the sacroiliac joint (Shadmehr et al 2012). Changes in neuromuscular control when performing an ASLR can even effect the control of respiratory muscles in order to try and force close the sacroiliac joint (O’Sullivan et al 2002). This is why pain in the sacroiliac joint is reduced during this test with bilateral compression to the ASIS in a medial direction to replicate the action of these muscles in force closing the sacroiliac joint.

    Innominate movement patterns in healthy and sacroiliac joint pain subjects were examined in prone hip abduction and external rotation (HABER). Innominate movement around a horizontal and vertical axis were analysed and they found:

    (a) Healthy controls: posterior rotation of the ipsilateral innominate (Adhia et al 2016) with rotation around a vertical axis either of both innominate bones towards the side being tested or in opposing directions (Bussey & Milosavljevic 2013).

    Example: if the left hip was placed in HABER the left innominate would rotate posteriorly with either or both innominate bones rotating to the left (not to the right) or the left innominate would rotate to the left (not to the right) and the right innominate to the right.

    (b) Sacroiliac joint positive subjects: posterior rotation of the innominate decreases as rotation around a vertical axis increases (Adhia et al 2016). This rotation around a vertical axis is always unilateral (i.e. both innominate bones always rotate to the same side) and this unilateral pattern was always to the same side regardless of what hip was placed in HABER.

    Example: if the left hip was placed in HABER the left innominate would posteriorly rotate but with a reduced movement. Rotation about a vertical axis would always include both innominate bones to one side only regardless of what leg was tested.

    References

    Clinical tests of the sacroiliac joint. A systematic methodological review. Part 1: Reliability. (2000). van der Wurff PHagmeijer RHMeyne W.

    Distraction test of the posterior superior iliac spine (PSIS) in the diagnosis of sacroiliac joint arthropathy (2013). Clément M L Werner, Armando Hoch, Lucienne Gautier, Matthias A König, Hans-Peter Simmen and Georg Osterhoff

    Innominate movement patterns, rotation trends and range of motion in individuals with low back pain of sacroiliac joint origin (2016). Divya Bharatkumar Adhia Stephan Milosavljevic SteveTumilty Melanie D.Bussey

    The sacroiliac joint: an overview of its anatomy, function and potential clinical implications (2012). A Vleeming et al

    Three pathways between the sacroiliac joint and neural structures (1999). Fortin JD, Washington WJ Falco FJ.

    Changes in recruitment of pelvic stabilizer muscles in people with and without sacroiliac joint pain during the active straight-leg-raise test (2012). Shadmehr AJafarian ZTalebian S.

    Referred pain location depends on the affected section of the sacroiliac joint (2015). Kurosawa D, Murakami E, Aizawa T.

    Referred leg pain originating from the sacroiliac joint: 6-month outcomes from the prospective randomized controlled iMIA trial (2016). Dengler J, Sturesson B, Kools D, Prestamburgo D, Cher D, van Eeckhoven E, Erk E, Pflugmacher R, Vajkoczy P7; and the iMIA study group.

    The diagnostic value of three sacroiliac joint pain provocation tests for sacroiliitis identified by magnetic resonance imaging (2017). Arnbak BJurik AGJensen RKSchiøttz-Christensen Bvan der Wurff PJensen TS.

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    Association of biomarkers of inflammation, cartilage and bone turnover with gender, disease activity, radiological damage and sacroiliitis by magnetic resonance imaging in patients with early spondyloarthritis.(2014). Almodóvar RRíos VOcaña SGobbo MCasas MLZarco-Montejo PJuanola X.

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  2. Introduction

    Rhomboid, Levator Scapula and Upper Trapezius dysfunction are commonly diagnosed in patients experiencing thoracic and cervical spine complaints. Less widely documented is the influence of the Serratus Anterior. Casteless (2016) documented a significant correlation with neck pain and impairment of Serratus Anterior activation.

    This functional relationship of the muscles is mirrored by their strong anatomical attachments to each other. This anatomical interaction is through dense aponeuroses and strong bands of connective tissue that attach the Rhomboids, Levator Scapula and Serratus Anterior into one muscular sheet.

    The topics in this article include:

    • Shared anatomical connections of the Rhomboids, Serrratus Anterior and Levator Scapula.
    • Anatomy and functions of the Levator Scapula, Rhomboids and Serratus Anterior.
    • Stretching the Serratus Anterior, Levator Scapula and Rhomboids. 

    Shared anatomical connections of the Rhomboid, Serratus Anterior and Levator Scapula

    (1) Scapula attachments

    Bharihoke & Gupta (1986) studied the attachments of the Levator Scapula, Rhomboid minor and major to the scapula. They found anterior and posterior attachment of these muscles to the scapula “enveloping” the bone. Standring (2017) found the enveloping of the Rhomboid Minor encloses the inferior boarder of the Levator Scapula. 

    The anterior attachments of all three muscles overlapped the costal surface of the Serratus Anterior fascia for about three centimeters. The fasciae of these muscles merges with each other along a straight line joining the free margins of their costal flaps (Barihoke & Gupta 1986).

    The continuity of the Serratus Anterior and the Rhomboid/Levator Scapulae has been described as a wide muscular sheet with a deep common fascia (Nguyen & Nguyen 1987).

    This continuity of the upper fibers of the Serratus Anterior and Levator Scapula not only dictates their dual function in suspending the scapula (Standring 2017) but anatomically is that of a composite aponeurosis (Nguyen & Nguyen 1986). This tough aponeurosis at the anterior supraspinous region of the scapula is also compounded by the Rhomboid Minor. The Rhomboid Minor has a tough wide anterior tendon extending 2-3 cm medial to and below the Levator Scapula where the fascia of the Rhomboid Minor and Serratus Anterior are fused (Standring 2017).

    Bharihoke & Gupta (1986) didn’t only notice the Rhomboids and Levator Scapula enveloping the scapula but the Serratus Anterior also. This muscle sandwiches the anterior and posterior surfaces of the superior and inferior angles of the scapula. Being attached to both surfaces of the scapula at these sites allowes for a posterior continuity of the Serratus Anterior and the Rhomboids and Levator Scapula.

    (2) Anterior rib attachments (including Scalene Medius)

    Smith et al (2003) and Webb et al (2018) followed these aponeurotic and fascial attachments between the Serratus Anterior and Levator Scapula. They found the fibers of the Serratus Anterior that attaches to the Levator Scapula course anteriorly around the body and constitute the Serratus Anterior's upper two ribs attachment (and occasionally the third, Smith et al 2003). Lifchez (2004) found these upper rib attachments thicker than the more inferior fibers.

    Hester et al (2000) identified a tight fascial band of tissue running from the inferior aspect of the brachial plexus, extending just superior to the Scalene Medius muscle insertion on the first rib and presented a digitation that extended to the proximal aspect of the Serratus Anterior muscle.

    (3) Extrathoracic fascia

    The common fascia covering and blending with this collective muscular sheet comprising the Serratus Anterior, Rhomboid, Levator Scapula and Trapezius is the extrathoracic fascia. Described by Latarjet and Juttin (1953) it's boundaries are: 

    Superiorly: blends with the aponeurosis of the Trapezius and Levator Scapula.

    Medially: vertebral attachment of the Rhomboid and latissimus dorsi extending down to T9.

    Lateral: anterior insertions of the Serratus Anterior (rib 2 to 8) at it’s fascia.

    Running medial to lateral the extrathoracic fascia blends with the aponeurosis covering the anterior surfaces of the Rhomboid and Serratus Anterior.

    Inferior: runs parallel to the body of the ninth rib or, less frequently, the ninth intercostal space. Thus its course is obliquely downwards and lateral. It is covered by the anterior surface of the latissimus dorsi medially and of the Serratus Anterior laterally.

    At the inferior border the extrathoracic fascia divides into two sheets:

    (a) the superficial sheet which blends with the anterior part of the aponeurosis of the Latissimus Dorsi medially and the Serratus Anterior laterally.

    (b) the deep sheet which is thinner than the superficial and merges with the thoracolumbar region.

    (4) Deep cervical fascia

    Syed et al (1953) identified the connections of the middle layer of the deep cervical fascia as providing a common fascia for the Omohyoid, Rhomboid and Levator Scapula.

    The authors separated the middle layer of the deep cervical fascia into three laminae of fascia:

    • Omosternal fascia.
    • Hyosternal fascia.
    • Visceral fascia.

    Only the omosternal and hyosternal fascia are covered here as they are intimately linked with the musculature.

    Omosternal fascia

    The Omosternal fascia is a thin lamina that ensheaths four muscles:

    a. Subclavius.

    b. Omohyoid (superior and inferior belly).

    c. Levator scapulae.

    d. Rhomboids.

    It also surrounds:

    a. Sternohyoid muscle.

    b. Omohyoid muscle.

    Boundaries:

    a. Superiorly: Hyoid bone where it blends with the superficial layer of the deep cervical fascia and the Hyosternal fascia.

    b. Anteriorly:

    Anterior triangle of the neck: blends at the superolateral margin of the omohyoid with the overlying superficial layer of the deep cervical fascia and the underlying hyosternal fascia.

    Median line: crosses the median line of the neck to the other side.

    c. Anterior-Inferiorly: manubrium and clavicle.

    d. Laterally:

    At the region of the Sternocleidomastoid:

    Blends with the superficial layer of the deep cervical fascia that surrounds the Sternocleidomastoid.

    Under the Sternocleidomastoid it forms a fascial pulley to permit the intermediate tendon of the Omohyoid to pass through.

    Posterior triangle of the neck: the omosternal fascia blends with the superficial layer of the deep cervical fascia along the inferior belly of the omohyoid and with the underlying hyosternal fascia. The omosternal fascia reaches along the omohyoid to the upper boarder of the scapula.

    e. Posteriorly-Inferiorly: between the scapula and the vertebral column it ensheaths the levator scapula and rhomboids 

    Hyosternal fascia

    ls a thin laminae of fascia similar to the omosternal fascia.

    Covers:

    a. Sternothyroid muscle.

    b. Thyrohyoid muscle.

    Boundaries:

    a. Laterally:

    At the Sternocleidomastoid: blends with the superficial layer of the deep cervical fascia surrounding the Sternocleidomastoid.

    Posterior triangle of the neck: blends with the omosternal fascia.

    b. Superiorly: Hyoid bone and Thyroid cartilage. At the Hyoid bone it blends with the superficial layer of the deep cervical fascia and the omosternal fascia.

    c. Anteriorly: crosses the midline of the neck to the other side.

    d. Inferiorly: posterior boarder of the manubrium sterni and medial part of the clavicle.

    Anatomy & function of the Levator Scapula, Rhomboids and Serratus Anterior

    Levator Scapula

    Attachment: C1-4 to supraspinous angle.

    Accessory attachments can exist to the mastoid process, occipital bone, rib 1 and 2, Scalene, Trapezius, Serratus Anterior and Serratus Posterior Superior. 

    Action: elevates the scapula and ipsilateral sidebends the cervical spine.   

    Rhomboid Major

    Attachment: T2-5 to medial boarder of scapula.

    Action: retracts the scapula superiorly and medially.

    Rhomboid Minor

    Attachment: C7-T1 to medial supraspinous boarder.

    Action: retracts the scapula superiorly and medially.

    Occasionally Rhomboid Occipitalis

    Attachment: upper boarder of Rhomboid Minor to occipital bone.

    Serratus Anterior

    Attachment: rib 1-8(-10) to the medial boarder of the scapula.

    Webb et al (2018) divided the Serratus Anterior into sections tracking the scapula attachments anteriorly to their rib attachments. They divided the Serratus Anterior into three divisions: 

    (1) Superior division: attaches to the superior angle of scapula (anterior and posteriorly) and rib 1 and 2.

    (2) Middle division: attaches to the medial boarder of scapula and rib 2 and 3.

    (3) Inferior division: attaches to the inferior angle of scapula (anteriorly and posteriorly) and rib 4 to 8/10.

    This makes makes the attachments of the Serratus Anterior to the Levator Scapula and Rhomboid continuous with the upper three ribs and the attachments of the Serratus Anterior and external oblique continuous with the inferior angle of scapula.

    Nguyen & Nguyen (1986) identified two differently oriented layers for the muscular digitations of the middle and inferior parts of the Serratus Anterior. Could this represent a dual function associated with the muscles own role on the scapula as well as this part of the muscle’s attachment and role in functionally working with the external oblique? (de Arauju et al 2018)

    Lifchez (2004) identified the Serratus Anterior muscle slips (i.e., the portion of the muscle that inserts on a rib) and subslips (superficial or deep subdivision of the slip). Deep subslips were thinner than superficial subslips and the most inferior slips were thinner than those of the superior slips. This would suggest a pronounced action of the superior fibers of the Serratus Anterior in functioning with the upper fibers of Trapezius and Levator Scapula in suspending the scapula.

    Action: all fibers protract the scapula with the pectoralis minor and fix the scapula against the thorax.

    Upper fibers: suspend the scapula with the Levator Scapula and upper fibers of Trapezius.

    Lower fibers protact the scapula to assist the upper fibers of Trapezius to raise the arm above the head.

    Stretching the Serratus Anterior, Levator Scapula and Rhomboids

    Stretching the Serratus Anterior

    Upper fibers: retraction and depression of the scapula. Due to the attachments of the fascial sling from the Scalene Medius to the Serratus Anterior could contralateral sidebending increase this stretch?

    Middle and inferior fibers: retraction of the scapula.

    Stretching the Levator Scapula, Rhomboid Minor and Major

    Best with the patient seated head face down on the bench (comfortably) elevated. With the patient's ipsilateral arm hanging by the side the scapula can be protracted/depressed for the Rhomboids and Levator Scapula using the relevant hand contacts.

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