Pelvic and Sacroiliac Joint Pain

Anatomy

The pelvis is the bony ringed structure connecting the spine with the lower extremities.  It forms a stable base of support for the spine and provides the attachment sites, both bony and muscular, for the lower limbs.  The sacrum is a bone with a roughly inverted triangular shape lying at the base of the spine.  It serves as a keystone at the rear of the pelvis.  All of the longitudinal forces applied to the lumbar are transmitted to the sacrum.

The pelvis is not a fused ring, however.  The sacrum forms a joint on each side with the ilium bone at the rear of the pelvis.  This produces a pair of sacroiliac joints.  These joints have both load bearing and stress-relieving functions.  They are long, irregularly shaped joints that are lined with cartilage.  The strength of the sacroiliac joints results from its partially interlocked bony structure and a number of strong reinforcing ligaments.

Sacroiliac joints transmit forces from the spine to the lower limbs, while also helping to absorb twisting forces generated by movement of the legs during activities, such as walking.  Anatomic studies suggest that only a few degrees of motion are permitted through the sacroiliac joints.

The Problem

The sacroiliac joints are recognized as a potential source of low back, buttock and even leg pain.  The frequency with which this occurs and the mechanism by which pain is produced are not as clear and are the subject of scientific debate.  Also, the extent to which alterations in sacroiliac joint motion may contribute to pain is unclear.  In the past, the sacroiliac joints were considered to be a common source of low back pain.  The focus on the lumbar disc as a primary source of pain has increased as the technology to visualize disc-related problems has advanced.

Diagnosis

Accurately diagnosing sacroiliac joint problems can be difficult because the symptoms mimic those of other back-related problems, including lumbar disc herniation, lumbar radiculopathy and lumbar facet syndrome. There is no single physical examination, x-ray or MRI finding that makes the diagnosis.  A combination of hands-on provocative tests of the pelvis and sacroiliac joints may help to improve diagnostic accuracy.

A sacroiliac joint injection, sometimes called a sacroiliac joint block, is the most useful diagnostic test for sacroiliac joint pain and dysfunction.  A small amount of local anesthetic is injected into the joint.  The sacroiliac joint is felt to be the source of pain if the injection relieves the patient’s symptoms. 

Treatment

Ice and a limited period of rest can help treat pain and acute inflammation.  Local heat can be useful after acute inflammation has ended.  Pain medications, including steroids and non-steroidal anti-inflammatories, can provide some relief. 

Manual or manipulation therapy can be effective in relieving pain and may serve to improve pelvic alignment and pelvic motion.  Exercise can help to restore low back flexibility and strengthen muscles about the low back, pelvis and the core.

Sacroiliac joint injections are used primarily to help establish whether or not the sacroiliac joints are the source of the patient’s pain.  Steroid can be added to the injection to help treat pain and inflammation.  Injections may be used to help the patient tolerate a more aggressive therapy program to enable a return to normal activities.