Unlike other peripheral joints, the sacroiliac joints do not have muscles that directly control their movement. However, because contraction of the muscles of the other joints may stress these joints or the symphysis pubis, the examiner must be careful during the active or resisted isometric movements of other joints and must be sure to ask the patient about the exact location of the pain on each movement. Table 10-1 outlines the muscles that attach to the pelvis. For example, resisted abduction of the hip can cause pain in the sacroiliac joint on the same side if the joint is injured, because the gluteus medius muscle pulls the ilium away from the sacrum when it contracts strongly. In addition, side flexion to the same side increases the shearing stress to the sacroiliac joint on that side. When doing active movements, the examiner is attempting to reproduce the patient’s symptoms rather than just looking for pain.

The sacroiliac joints move in a “nodding” fashion of anteroposterior rotation. Normally, the PSISs approximate when the patient stands and separate when the patient lies prone. When he or she stands on one leg, the pubic bone on the supported side moves forward in relation to the pubic bone on the opposite side as a result of rotation at the sacroiliac joint.

The stability at the sacroiliac joint is determined by three factors—form closure, force closure, and motor control along with psychological aspects.^12,34 Form closure refers to the close packed position of the joint where no outside forces are necessary to hold the joint stable. Thus, intrinsic factors such as joint shape, coefficient of friction of the joint surfaces, and integrity of the ligaments contribute to form closure.^5,12,35 Force closure would be similar to the loose packed position in that extrinsic factors, primarily the muscles and their neurological control, along with the capsule are needed to maintain stability of the joint as well as the forces applied to the joint.^5,12,35 These two forms of closure and neurological control enable the sacroiliac joints to self lock as they go into close pack and slightly release when the joint unlocks.

During the active movements of the pelvic joints, the examiner looks for unequal movement, loss of or increase in movement (hypomobility or hypermobility), tissue contracture, tenderness, or inflammation.

The movements of the spine put a stress on the sacroiliac joints as well as on the lumbar and lumbosacral joints. During forward flexion of the trunk, the innominate bones and pelvic girdle as a whole rotate anteriorly as a unit on the femoral heads bilaterally. The same thing occurs when one rises from supine lying to sitting. If one leg is actively extended at the hip, the innominate on that side will unilaterally rotate anteriorly.⁵ During the anterior rotation of the innominate bones (counternutation), the innominate slides posteriorly along its long arm and inferiorly down its short arm (Figure 10-17).⁵ Initially, the sacrum nutates up to about 60° of forward flexion, but once the deep posterior structures (deep and posterior oblique muscle systems, thoracolumbar fascia, and the sacrotuberous ligament) become tight, the innominates continue to rotate anteriorly on the femoral heads, but the sacrum begins to counternutate.⁵ This counternutation causes the sacroiliac joint to be vulnerable to instability as greater muscle action (force closure) is required to maintain stability with counternutation.⁷ Thus, the earlier counternutation occurs during forward flexion, the more vulnerable is the sacroiliac joint to instability problems. Excessive counternutation is more likely to occur in patients who have tight hamstrings.⁵

To test forward flexion, the patient stands with weight equally distributed on both legs. The examiner sits behind the patient and palpates both PSISs (Figure 10-18). The patient is asked to bend forward (see Tables 10-2 and 10-3) and the symmetry of movement of the PSIS superiorly is noted. At the same time, the examiner should note the amount of flexion that has occurred when sacral nutation begins. This can be done by having the patient repeat the forward bending motion while the examiner palpates the PSIS (inferior aspect) on one side with one thumb while the other thumb palpates the sacral base so the thumbs are parallel. In the first 45° of forward flexion, the sacrum will move forward (nutate) (Figure 10-19, A), but near 60° (normally), the sacrum will begin to counternutate or move backwards (Figure 10-19, B).⁵ During the sacral counternutation, the two PSISs should move upward equally in relation to the sacrum and toward each other or approximate. At the same time, the ASIS will tend to flare out.

During extension, the opposite movements occur (see Tables 10-2 and 10-3).^5,8 During extension or backward bending of the trunk, the innominate bones (the pelvic girdle) as a whole unit rotate posteriorly (nutation) on the femoral heads bilaterally. If one leg is actively flexed at the hip, the innominate on that side unilaterally rotates posteriorly.⁵ During the posterior rotation of the innominate bones, the innominate slides anteriorly along the long arm and superiorly up the short arm. This movement is the same as sacral nutation (Figure 10-20). With backward bending, both PSISs move inferiorly an equal amount.

To test backward bending, the patient stands with weight equally distributed on both legs. The examiner sits behind the patient and palpates both PSISs. The patient is asked to bend backwards while the examiner notes any asymmetry (Figure 10-21). Normally, the PSISs move inferiorly. During backward bending, the innominate bones and sacrum remain in the same position, so there should be no change in their relationship.⁵ The examiner palpates both sides of the sacrum at the level of S1. As the patient extends, the sacrum should normally move forward. This is called the sacral flexion test.

Side flexion normally produces a torsion movement between the ilia and the sacrum. As the patient side flexes, the innominate bones bend to the same side and the sacrum rotates slightly in the opposite direction; the thumb of the examiner on the same side (the thumbs are palpating on each side of the sacrum at the level of S1) moves forward. This is called the sacral rotation test.⁵ If this torsion movement does not occur (e.g., in hypomobility), the patient finds that more effort is required to side flex and it is harder to maintain balance.⁸

During rotation, the pelvic girdle moves in the direction of the rotation causing intrapelvic torsion. The innominate, which is on the side to which rotation is occurring, rotates posteriorly while the opposite innominate rotates anteriorly, pushing the sacrum into rotation in the same direction (i.e., right rotation of the trunk and pelvis causes right rotation of the sacrum). This causes the sacrum to nutate on the side to which rotation occurs and counternutate on the opposite side.⁵

The hip movements performed are also affected by sacroiliac lesions. As the patient flexes each hip maximally, the examiner should observe the ROM present, the pain produced, and the movement of the PSISs. The examiner first notes whether the PSISs are level before the patient flexes the hip. Normally, flexion of the hip with the knee flexed to 90° or more causes the sacroiliac joint on that side to drop or move caudally in relation to the other sacroiliac joint (Gillet test). If this drop does not occur, it may indicate hypomobility on the flexed side. The examiner can observe this movement by placing one thumb over the PSIS and the other thumb over the spinous process of S2 (Figure 10-22, A). In the patient with a normal sacroiliac joint, the thumb on the PSIS drops (Figure 10-22, B). If it is hypomobile, the thumb moves up on hip flexion. The two sides are compared. Sturesson and colleagues³⁶ have questioned whether much movement occurs at all because the stress of doing the test on one leg causes “force closure” of the sacroiliac joints, thus limiting movement.

The examiner then leaves the one thumb over the sacral spinous process and moves the other thumb over the ischial tuberosity (Figure 10-22, C). The patient is again asked to flex the hip as far as possible. Normally, the thumb over the ischial tuberosity moves laterally (Figure 10-22, D). With a fixed or hypomobile joint, the thumb moves superiorly or toward the head. Again, the two sides are compared.

The examiner then sits in front of the standing patient and palpates the ASIS. Testing one leg at a time, the patient pivots the leg on the heel into medial and lateral rotation. When doing these movements, the ASIS should move medially and laterally. Both sides are compared.⁵

The position of the sacrum can then be determined. To do this, the examiner tests the patient in two positions—sitting and prone—doing three movements: flexion, staying in neutral, and extension. Before testing, the examiner palpates the base of the sacrum and the inferior lateral angle (near apex) of the sacrum on both sides (Figure 10-23). Normally, the sacral bone and the inferior lateral angle of the sacrum are level (i.e., one is not more anterior or posterior than the other). The first test involves the patient sitting with the feet supported and the spine fully flexed. The examiner palpates the four points (Figure 10-24) and determines their relationship to one another. The patient is then put in prone lying with the spine in neutral and the relationship of the four points determined. The examiner then asks the patient to fully extend the spine and then determines the relationship of the four points. In any of the positions tested, if the examiner found, for example, an anterior left sacral base along with a posterior right inferior lateral angle, it would indicate a left rotated sacrum.⁵

The final active movements of the pelvis that the examiner may observe is the action of the pelvic floor muscles (Table 10-5). If the pelvis has been found to be unstable or the patient is suffering from incontinence, the examiner can ask the patient to contract the muscles by asking the patient to squeeze the muscles tight by trying to stop peeing and hold the contraction. With strong pelvic floor muscles, the patient should have little trouble holding the contraction for at least 30 seconds.

The passive movements of the pelvic joints involve stressing of the ligaments and the joints themselves. They are not true passive movements, like those done at other joints, but are in reality stress or provocative tests. It should be noted, however, that the effectiveness of these tests in confirming sacroiliac joint problems has been questioned even when combined in a clinical prediction rule.31,37 Lee¹² feels these passive movements or tests should be used to determine symmetry or asymmetry of stiffness rather than normal, hypermobile, or hypomobile. It is her contention that asymmetry at the two sacroiliac joints is the problem, not the amount of movement. Laslett, et al.³⁸ and van der Wurff, et al.³⁹ felt that individually the sacroiliac provocative tests were not reliable enough to make a diagnosis, but a combination of the tests were. They felt that if two of four tests were positive (see box on the next page), these tests were the best predictors of an intra-articular sacroiliac joint block. If all six tests were negative, sacroiliac joint pathology could be ruled out.⁴⁰ Doing the passive movement is more likely to eliminate muscle tension effects that cause compression and increased stiffness.¹² Because of their anatomic makeup, the pelvic joints do not move to the same degree or in the same fashion as other joints of the body. When doing these provocative passive movements/tests, the examiner is looking for the reproduction of the patient’s symptoms, not just pain or discomfort.^33,41

 Approximation (Transverse Posterior Stress) Test.5,38

The patient is in the side lying position, and the examiner’s hands are placed over the upper part of the iliac crest, pressing toward the floor (Figure 10-25). The movement causes forward pressure on the sacrum. An increased feeling of pressure in the sacroiliac joints indicates a possible sacroiliac lesion and/or a sprain of the posterior sacroiliac ligaments.

 Femoral Shear Test.

The patient lies in the supine position. The examiner slightly flexes, abducts, and laterally rotates the patient’s thigh at approximately 45° from the midline. The examiner then applies a graded force through the long axis of the femur, which causes an anterior-to-posterior shear stress to the sacroiliac joint on the same side (Figure 10-26).⁴²

 Gapping (Transverse Anterior Stress or Distraction Provocation) Test.5,38

The patient lies supine while the examiner applies crossed-arm pressure to the ASIS (Figure 10-27, A) (some examiners prefer not to cross arms, Figure 10-27, B). The examiner pushes down and out with the arms. The test is positive only if unilateral gluteal or posterior leg pain is produced, indicating a sprain of the anterior sacroiliac ligaments. Care must be taken when performing this test. The examiner’s hands pushing against the ASIS can elicit pain, because the soft tissue is being compressed between the examiner’s hands and the patient’s pelvis.

 Ipsilateral Prone Kinetic Test.5,8

This test is designed to assess the ability of the ilium to flex and to rotate laterally or posteriorly. The patient lies prone while the examiner places one thumb on the PSIS and the other thumb parallel to it on the sacrum. The patient is then asked to actively extend the leg on the same side (Figure 10-28). Normally, the PSIS should move superiorly and laterally. If it does not, it indicates hypomobility with a posterior rotated ilium, or outflare.

 Passive Extension and Medial Rotation of Ilium on Sacrum.5,8

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