Background:

The piriformis muscle is a short, thick muscle that runs from the outside aspect of the sacrum to the lateral bony portion of the hip. This muscle’s primary function is in external rotation of the hip, it helps with extension and taking the leg away from the body. This muscle can become injured form overuse, it can react to an injury of the sacroiliac joint, or it can be injured with significant trauma. Whatever the cause, initially the muscle starts to spasm and tighten up, just like when any other muscle is injured. 

The problem occurs when this muscle begins to exert compression on the sciatic nerve as it passes by the muscle. Anatomically the sciatic nerve can run either over the piriformis muscle, under the piriformis muscle and in less common cases the nerve will pierce through the muscle belly. Whatever the arrangement, when the injured piriformis muscle tightens up and compresses the sciatic nerve, pain similar to sciatica can be produced. The primary difference between Piriformis Syndrome and sciatica, besides for the cause of the pain, is that Sciatica pain will usually extend all the way down the leg and into the foot whereas the pain from Piriformis Syndrome will usually only extend to the knee.  

Signs and Symptoms:

Someone suffering from Piriformis Syndrome will describe pain and possibly numbness or weakness in the back, buttock or hip area and the symptoms may or may not extend down into the leg. The affected side will classically develop a laterally deviated foot, when you look down at your feet when you are standing or laying you will see the toe pointing outward in a laterally deviated foot. The piriformis muscle will be extremely tender to palpation and by putting pressure on the muscle the symptoms will be reproduced.

Treatment: