Semimembranosus insertion syndrome: a treatable and frequent cause of persistent knee pain.

The semimembranosus insertion syndrome causes pain at the medial aspect of the knee. This pain is aggravated by exercise, walking downstairs and sharp bending of the knee. The patient experiences tender, moderately puffy swelling at the lowest part of the medial hamstrings muscles and painful passive rotation of the knee, while finger pressure over the insertion of the semimembranosus tendon elicits sharp pain. One hundred patients with semimembranosus insertion syndrome were treated with local injection of lidocaine hydrochloride and triamcinolone. All experienced temporary relief of pain immediately. Long-lasting relief of signs and symptoms was achieved in 58 patients, 30 of whom required repeat injections in 3 to 5 months. Pain decreased and disability was less severe in 9 other patients. There were 18 treatment failure, and 15 patients were lost to follow-up.