DIAGNOSIS AND TREATMENT THE SACROILIAC By Howard Turner, MCSP

CLINICAL SIGNIFICANCE The SIJs as a source of pain Pain of sacroiliac joint origin is actually well documented and relatively common. Injection studies have identified that some 20% of the chronic low back pain population have SIJ-mediated pain (2,3). With a nerve supply of L2-S4 its pain pre- sentation is variable but it commonly pro- duces buttock and posterior thigh pain, can refer to the groin and adductor area and, contrary to traditional thought, is just as common a source of referred leg and foot pain as the lumbar spine (3).

Injection studies, of course, can only comment on intracapsular sources of pain. Many other potential sources of pain in the area have been proposed, most notably the surrounding ligaments, so these figures may underestimate the true proportion of SIJ-related pain.

The SIJs and dysfunction elsewhere Clinical interest in the sacroiliac joints extends beyond its capacity to produce pain in certain patients. Movement dys- function of the sacroiliac joints and pelvis appear related to a wide variety of clinical presentations both up and down the kinetic chain, in particular disorders of the lumbar spine and certain lower limb problems.

There has long been interest in the sacroiliac joints (SIJs) in relation to back pain but it has not been without controversy. At the beginning of the 20th century the joints were considered the major source of sciatic distribution pain (1) and yet there are many today who would subscribe to an idea dating back to Hippocrates time - that the sacroiliac joints are immobile, except during pregnancy, and cannot cause pain. It is only relatively recently that research has provided a clear insight into the biomechanics of the pelvis, and therefore an improved understanding of the mechanisms of pain production.

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Their effect on the lumbar spine must at least in part be mechanical - a disruption of normal movement and load transfer through the pelvis must alter the forces acting on the spine and impose con- straints upon its movement, which in turn may be involved in the development or perpetuation of pain-provoking movement patterns.

There also appears to be a relationship between SIJ function and the function of local stabilising musculature. Whilst it may not be entirely analogous, Indahl’s study on the porcine SIJ showed that stimulation of the joint and its capsule stimulated predictable and reproducible

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