Recalcitrant patellar tendinitis. Magnetic resonance imaging, histologic evaluation, and surgical treatment.

Magnetic resonance imaging findings and the results of surgical treatment and histologic evaluation of 11 knees in 9 athletes with recalcitrant patellar tendinitis are reported. All of the athletes had no improvement with traditional nonoperative treatment and all had abnormal magnetic resonance imaging findings consistent with chronic patellar tendinitis. Surgical exploration and debridement were performed on the 11 knees by the same surgeon. With a minimum followup of 1 year, 7 of the 11 knees had excellent results, 3 had good results, and 1 had a poor result. Histologic evaluation of the debrided tissue was consistent with "angiofibroblastic tendinosis," which correlated with the abnormal preoperative magnetic resonance imaging findings in the proximal third of the infrapatellar tendon. This study correlated histologic findings with magnetic resonance imaging findings and shows that in selected patients excellent results can be achieved with surgical treatment of recalcitrant patellar tendinitis or "jumper's knee."