Early diagnosis of acute rupture of the quadriceps tendon by arthrography.

Arthrographic study of the knee was performed in six patients for diagnosis of acute rupture of the quadriceps tendon. All of the patients gave a history of attempting to recover from a fall. Pain and tenderness over the suprapatellar area were common findings in all patients. Four patients had a positive arthrogram demonstrating extravasation of the radiopaque material outside the knee along the quadriceps tendon. Of these four patients, two had complete loss of quadriceps function, but the other two were able to partially extend the knee when the gravity was eliminated. Two patients had negative arthrograms; both had loss of active extension of the knee against gravity but were able to extend the knee when the gravity was eliminated. All four patients with a positive arthrogram had rupture of the quadriceps tendon, which was demonstrated at the time of surgery. In one patient with a negative arthrogram, exploration of the knee revealed an intact extensor mechanism. Arthrography of the knee is an aid to the diagnosis of rupture of the quadriceps tendon and when indicated can be performed in the emergency room.