Hypertrophy of the synovium in the anteromedial aspect of the knee joint following trauma: an unusual cause of knee pain.

PURPOSE The purpose of this study was to describe the arthroscopic clinical findings and treatment in patients with pathologic hypertrophy of the synovium in the anteromedial joint compartment in conjunction with anteromedial knee pain. TYPE OF STUDY Case series. METHODS A group of 21 patients, ranging in age from 11 to 68 years (mean, 29 years) with pathologic hypertrophic changes of the synovium in the anteromedial joint compartment were studied. Pathologic changes included inflammation, polyp-type appearances, or hypertrophic string forming a loop. The most significant clinical finding was pain in the anteromedial aspect of the knee joint. Of the 21 cases, 20 (95%) had a history of trauma to the involved knee. Assessments performed included Lysholm knee scores with a special emphasis on knee pain. The duration of symptoms ranged from 2 to 32 months (mean, 13 months). Treatment consisted of an arthroscopic evaluation followed by debridement of the hypertrophic synovium using a laser, shaver, or thermal debrider. RESULTS The mean follow-up was 5.1 years (1.2 to 10 years). Mean Lysholm score improved from 64.1 to 96.4 (P <.05). Specifically, the pain score improved from 4.3 to 23 (P <.05). All patients were free of pain within 3 weeks following arthroscopic debridement. Return to normal function, including sports, was achieved for all patients within 2 months. Arthroscopic evaluation revealed that 18 of 21 (86%) knees had mild chondral damage on the medial femoral condyle, grade I or II according to Outerbridge grading. CONCLUSIONS Based on the clinical and arthroscopic findings, we concluded that pathologic hypertrophy of the synovium in the anteromedial joint compartment may result following trauma, causing mild chondromalacia changes in the medial femoral condyle and knee pain. Arthroscopic debridement of this pathologic tissue significantly improves symptoms.