Piriformis syndrome has been recognised as a source of buttock and leg pain for 80 years, but it is still a controversial diagnosis. The pain is thought to be related to the proximity of the muscle to the sciatic nerve in the buttock and irritation or compression of the nerve have been suggested as causes. Physiotherapists diagnose and treat piriformis syndrome regularly, as it can often be mistaken for sciatica.
The piriformis muscle is flat and small, lying in the centre of the buttock, taking its origin from the sacral area and inserting on to the top of the greater trochanter of the thigh, the bony prominence easily felt on the side of the leg below the hip. It either turns the leg outwards or moves the thigh away from the body, depending on the position of the hip. The sciatic nerve and the piriformis muscle vary in their structure and position in the buttock. Typically the muscle lies behind the nerve but in some cases the piriformis is divided into two parts with the sciatic nerve passing between them.
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.
The physiotherapist may find tightness in the piriformis and hip muscles and institute a treatment regime of stretches after loosening up the hip muscles. To stretch the piriformis the patient lies on their back, bends up the hip to 90 degrees and moves the hip across the body with the opposite hand, holding at the end of the stretch. A home exercise programme of stretches is set for regular performance, with the stretches being done every few hours in the more acute episodes. The Physio may find the piriformis muscle is stretched rather than tight, leading them to work on strengthening it up and stretching the opposing tight structures.
Local manipulation is a common treatment directly over the most painful point in the buttock, which can be very tender indeed. Transverse or longitudinal mobilisations over the muscle is the technique used, maintaining the pressure steadily for up to 10 minutes initially. Treatment of the back and sacro-iliac joints is important to address any dysfunction which might contribute. Modifying posture and activity, muscle injections, mobilisations and stretching are commonly successful in reducing symptoms. In resistant cases surgery to the muscle or the tendon at the greater trochanter may be contemplated.