[Rupture of the quadriceps tendon; cannot be missed?]

In four patients, two men aged 59 and 68 years and two women aged 59 and 50 years, a unilateral rupture of the quadriceps tendon was diagnosed. In two patients the disease was initially misdiagnosed. A depression was palpable in all patients just on the proximal side of the patella. All patients were treated operatively and all recovered with satisfactory knee function. In order to obtain full recovery early aetiological diagnosis is important; quadriceps tendon rupture should be considered in patients with haemarthrosis and inability to stretch the knee.