Since 1928 Piriformis Syndrome has been described as a source of buttock and leg pain, often confused with sciatic type leg pain of lumbar origin. The sciatic nerve and the piriformis muscle lie very close to each other in the buttock and the pain has been attributed to nerve irritation or compression, without much convincing evidence. Not universally recognised as a diagnosis, piriformis syndrome is regularly diagnosed and treated by physiotherapists.

The piriformis muscle (Latin for pear-shaped) is one of the smaller central buttock muscles, passing as a flat layer from the front of the sacral region and ending by its insertion into the top of the femoral greater trochanter, the large bony structure easily found with the hand on the outside of the thigh near the hip. Its actions vary with the position of the hip joint and can either be external rotation or abduction of the hip. The anatomical relationship between the sciatic nerve and the piriformis muscle is subject to some variation in individuals, with the sciatic nerve commonly passing in front of the muscle but in others the nerve can pierce the muscle or pass between two bellies.

Piriformis syndrome has no clear cause of onset and may occur with sacro-iliac and lumbar spinal syndromes. Direct damage to the buttock could cause scar tissue around the muscles and the nerve, while continual pressure over time could also alter the nerve's function. Other factors could be an increased lumbar curve, strong activity and hip replacement, with some cases imitating back pain problems such as sciatic pain. Diagnosis and treatment of piriformis syndrome is performed by physiotherapists on clinical findings due to the lack of diagnostic and imaging investigations.

Low back pain and leg pain can be lumbar or sacro-iliac in origin, but piriformis syndrome is a poorly recognised cause of these symptoms, simulating the picture of a disc protrusion or joint arthritic change. Trochanteric bursitis occurs over the area of the trochanter which also carries the insertion of the piriformis tendon, linking the two syndromes clinically. Physiotherapy examination clinically will note acute trigger point tenderness in the buttock, a reduction in hip lateral rotation, reduced power and pain on testing of hip abductor and lateral rotator strength and difficulty sitting on the affected buttock.

No scientific evidence exists for the usefulness of any particular physiotherapy treatment, especially as there are no agreed diagnostic criteria. Physiotherapy examination includes finding the physical restrictions such as tight muscles (piriformis, hip adductors, hip external rotators), joint stiffness and dysfunction (sacro-iliac joint and lumbar spine), walking with an outwardly turned hip, an apparently short leg and a shorter length of stride.

There may be tightness in the hip and piriformis muscles and in these cases the physiotherapist will start a programme of muscle stretches after warming up the hip muscles. Piriformis stretches are taught in lying, the hip positioned in 90 degrees, stretching the thigh over the other leg and pulling it with the other hand. The patient will need to follow a home exercise programme of muscle stretches, up to every few hours in cases of an acute nature. Stretching the piriformis may not be appropriate if the muscle is loose or stretched, in which case muscle strengthening and stretching of the opposing stiff areas is used.

Direct manipulation of the most tender spot in the central area of the buttock is a very useful treatment technique commonly used by physiotherapists. Longitudinal or transverse mobilisation techniques are employed on the muscle, with stronger pressure and longer periods being used as the pain reduces. The Physio will treat any contributory dysfunction of the lumbar spine or sacro-iliac joint. Taking this conservative approach is often helpful in reducing symptoms of this syndrome using mobilisation treatment, deep injections, changing typical activities and postures and setting a stretching regime. Where the problem is severe and does not settle then surgery to the tendon insertion or to the muscle may be considered.