Radiographic diagnosis of quadriceps tendon rupture.

Traumatic rupture of the quadriceps tendon is an uncommon knee injury which occurs in the elderly, and/or the obese, and in those with underlying systemic disease. Ten patients with 13 ruptures have been seen at the Massachusetts General Hospital in the last nine years. Clinically, the patient is unable to actively extend the knee. On the lateral view of the knee there is loss of normal quadriceps outline and a soft-tissue mass with calcification representing the retracted quadriceps tendon. Most patients have a hemarthrosis. The clinical diagnosis is often overlooked, and the radiologist could be the first to suggest the diagnosis.