Sciatica and the Sacroiliac Joint

The sacroiliac joint is the location where your pelvic bones articulate with the sacrum. If you look at someone from behind you will notice a divot or dimple on either side of the spine in the low back above the buttocks. This point is called the PSIS or Posterior Superior Iliac Spine. The sacroiliac joint lies deep to this landmark. When things are functioning properly the two pelvic bones rotate very slightly at this joint when we walk.

If you have injured this joint the deep pelvic muscles that surround the joint will react by increasing their tone and will in turn restrict the rotational movement that would normally be there. In the short term this is probably a good coping mechanism for the body to deal with an acute joint injury as it essentially eliminates any stress to the articular surfaces. However in the longer term, when things don't return to normal biomechanic movement patterns, pain and abnormal movement can persist.

The pain that can arise from this joint is often mistaken for sciatica.

True sciatica is caused by pressure or irritation to the sciatic nerve. The nerve is made up nerve roots that exit the spinal canal in the lumbar spine. Pressure or irritation to this nerve can cause pain down the back of your leg.

There are a few ways to distinguish between true sciatica and sacroiliac pain.True sciatica can be felt all the way down the back of the leg past the knee and sometimes includes pain to the toes. Sacroiliac leg pain typically doesn't travel past the knee. Another distinguishing feature is pain that predominates on one side over the region of the PSIS. This one sided low back pain almost always presents on the same side as the "pseudo sciatica".

There is an easy test that one can try at home to distinguish sacroiliac pain from sciatica. Get a partner to stand behind you with their hands on your hips. Bend forward and then straighten back to the original upright position. If there is mechanical pain in the low back, this movement usually provokes it. Now to distinguish between sciatica and sacroiliac joint pain do the same movement but get your partner to stabilize your hips by blocking movement at the hip. As you bend forward your hip should be pulled tight to your partners leg or hip to prevent forward rotation of your hip. If done correctly this maneuver will either provoke your back pain or make it better depending on which problem is the cause. If the forward bending movement is much less painful when the hip movement is blocked it suggests that the sacroiliac joint is the source. If it greatly increases the pain, it points to lumbar disc issues that can cause sciatica.

Sacroiliac joint dysfunction is one of the most common disorders seen in a chiropractic office. Chiropractors are well trained to recognize this condition and should be considered when considering treatment options.