Patellar tendonitis and anterior knee pain.

Patellar tendonitis or "jumper's knee" is an important cause of anterior knee pain. The natural history, classification of the lesion, and treatment methods, however, remain controversial. This article presents a retrospective review of 40 patients (50 knees) with various stages of patellar tendonitis and examines the etiology, presentation, clinical picture, investigation, and results of conservative treatment. Twenty-nine men and 11 women ranging in age from 17-48 years comprised the study population. Ten patients had bilateral involvement. The overall evaluation of patients' treatment was 70% with normal or nearly normal results and 30% with abnormal or very abnormal results; most required surgical treatment in the form of arthroscopy, anterior compartment decompression, and patellar tendon exploration. Thirty-seven percent of the patients had a previous history of anterior knee pain (25% had Osgood-Schlatter disease and 12.5% had anterior knee pain). Patellar tendon involvement is appraised according to a new concept. Since patellar tendonitis is part of the wider picture of anterior knee pain, patellar tendonitis is classified as primary or secondary according to presentation, magnetic resonance imaging in general, and the pathology of the patellar tendon in particular. Treatment is planned accordingly.