Clinical features:
(1) buttock pain
(2) pain radiating down the posterior thigh and leg along the sciatic nerve
(3) buttock pain while walking up an incline or climbing stairs
Risk factors:
(1) history of pelvic trauma
(2) overuse of the hip
(3) prolonged sitting
(4) hypertrophy of the piriformis muscle
(5) disease of the piriformis muscle
Testing:
(1) pain on palpating the piriformis muscle as it runs from the greater trochanter to the sacrum
(2) positive Trendelenburg test
(3) positive FAIR (flexion, adduction, internal rotation) test while supine
(4) negative FAIR test 1 hour after injection of lidocaine and corticosteroids into the implicated piriformis muscle
Differential diagnosis:
(1) ischiogluteal bursitis
(2) herniated lumbar disc
(3) other causes of sciatic nerve compression
(4) sacroiliac joint dysfunction
