Piriformis Syndrome is an impingement syndrome that occurs when the piriformis muscle compresses the sciatic nerve. This causes pain in the buttocks region and may even result in referred pain in the lower back and thigh or leg. In addition to pain, weakness and even numbness or tingling may be felt in the same regions.
The piriformis muscle is a small muscle deep in the buttocks that rotates the leg outwards. It runs from the sacrum (the base of the spine) and attaches to the top of the femur (thigh bone). The sciatic nerve runs under this muscle and down the leg, although in about 10% of the population it actually runs through the muscle fibers.
Piriformis syndrome is predominantly caused by a shortening or tightening of the piriformis muscle. This can occur when the piriformis muscle is overloaded from activities such as exercising on hard surfaces or uneven ground, increasing exercise intensity too quickly, or sitting for long periods of time. Biomechanical inefficiencies can also lead to piriformis syndrome. This can include faulty foot and body mechanics, gait disturbances and poor posture or sitting habits.