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Inside Spinal Pelvic Stabilizer Research
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Sacroiliac Subluxations and Low Back Pain

The sacroiliac joints (SI) are the source of many symptoms categorized as ‘mechanical low back pain.’ Estimates of the prevalence of painful sacroiliac problems in patients with low back pain vary widely, from 22.5%,1 up to 88%.2 Such a range is probably due to variances in definitions, testing methods, and patient selection. While a pattern of unilateral pain extending from the lowest part of the spine into the buttock and down the back of the upper leg is classic (Fig. 1), this, too, can vary significantly from one patient to the next. Effective chiropractic care of spinal problems can proceed only when the sacroiliac joints are evaluated and all subluxations and malfunctions are addressed.

Sacroiliac joint pain can interfere with standing, walking, lifting, and changing positions. When sacroiliac dysfunction is not cared for appropriately, chronic back pain can develop. Misdiagnosed patients may undergo a discectomy or spinal fusion surgery, with little to no relief. Fortunately, most sacroiliac conditions respond well to chiropractic care, especially when accompanied by custom-made Spinal Pelvic Stabilizer Orthotics and rehabilitative exercise.

Sacroiliac Joint Function

Anatomy. The pelvic ring is made up of two innominate bones that join anteriorly at the pubic symphysis and are separated posteriorly by the sacrum. The main function of the sacroiliac joints is to support the vertebral column and transmit motion and weightbearing between the spine and the pelvis and lower extremities (Fig. 2). The upper portion of each sacroiliac joint is a fibrous articulation, while the lower two thirds is a true synovial joint. A small amount of movement occurs in these joints, in spite of the irregular surfaces and very strong anterior, interosseous, and posterior ligaments.3 In the fifth decade of life, fibrosis begins to take place between the cartilage surfaces, reducing mobility.4 True bony anklyosis is a rare phenomenon late in life.5 No muscles cross the joints, but the gluteus maximus, piriformis, and long head of the biceps femoris muscles attach into the sacrotuberous ligament, and may influence sacroiliac joint movement and stability.6

Biomechanics. The sacroiliac joints do not flex and extend or rotate. Because of their complex anatomy, the axis of joint motion is unique, and the movement of the sacroiliac joints is called ‘nutation.’7 Most of the important work of the sacroiliac joint occurs during gait. With each step, one leg swings forward and the pelvis twists forward on that side. At heel strike, the leg is externally rotated and the ilium is posterior (PI). As the foot and ankle pronate, the leg rotates inward and the sacroiliac joint ‘contranutates.’8 The ilium moves anterior (AS) during mid-stance. As the foot and ankle supinate and the leg rotates outward, the opposite movement (nutation) now brings the ilium posterior. If this complex movement pattern is disrupted, gait abnormalities and pelvic-region pain develop.

The ground reaction forces that are generated during gait (and especially when running) result in two additional phenomena:

1. Because of the irregular contour of the joint surfaces, sacroiliac movement occurs only when there is enough force to overcome ligamentous resistance. This is thought to constitute a shock-absorbing mechanism.9
2. When there is a difference in leg lengths, the increased ground reaction force from the longer leg causes the ipsilateral ilium to rotate more
posteriorly.10 The higher forces and repetitive
subluxation of the sacroiliac joint may be the underlying cause of the increased frequency of low back pain seen in patients with a leg length discrepancy.11

Acute sprain. The sudden onset of unilateral sacroiliac pain is usually caused by forceful twisting, or heavy lifting (especially from a stooped position). Stepping off a curb, and even twisting in bed have also been reported as causes. The provocative tests for the SI joint — such as Gaenslen’s (Fig. 3) and Yeoman’s (Fig.4) — is positive, increasing the local pain. Initial care consists of a protective support (trochanter brace), activity restrictions (especially weightbearing), and cryotherapy. Adjustments should be performed cautiously, to avoid overstretching the stabilizing ligaments (Fig. 5).12 Once the acute phase has subsided, an in-depth evaluation of the biomechanics of the pelvis and lower extremities should be done. This discloses any predisposing factors such as excessive pronation, leg length inequality, or muscle imbalance. Caring for these factors prevents chronicity.

Sacroiliac syndrome. Recurrent problems and non-traumatic subluxations of the sacroiliac joints are usually due to an acquired instability. These patients may be athletes, post-partum females, or in their middle age. Pain is usually aggravated by prolonged or repetitive weightbearing activities. These patients have a chronic dysfunction of the joint, which may now be undergoing degeneration. They often get dramatic relief from specific sacroiliac adjustments, but the condition tends to recur. A search for underlying gait asymmetries and biomechanical imbalances is needed.

Other factors. It is very important to recognize the functional short leg, since providing a lift instead of an orthotic is likely to perpetuate the associated sacroiliac subluxations.13 And there is no reliable information on the radiographs to differentiate these conditions. A pelvic tilt, a lower sacral base, and a femur head discrepancy indicate a lower extremity source, but not whether it is an anatomical or a functional short leg. A good clinical postural exam with lower extremity screening (including shoe wear patterns) is the only way to make this determination.

Orthotic Support

Because the SI joints are so intimately involved in gait, orthotic support for the feet is often a necessary component of care in sacroiliac conditions:

Rehabilitative Support

Corrective exercises done at home to strengthen supporting muscles can be recommended as an adjunct to clinical treatment. Activity should focus on developing strength in the abdominals and supporting pelvic muscles. This can also enhance the shock-absorbing properties of the tissues. Foot Levelers’ BACKSYS® exercise program is especially suited for SI rehabilitation (Figs 7a and 7b).

Adjunctive Care for Total Support