Localized Synovial Hypertrophy in the Anteromedial Compartment of the Osteoarthritic Knee

Purpose: The purpose of this study was to investigate the clinical and arthroscopic findings of osteoarthritis (OA) of the knee with localized synovial hypertrophy in the anteromedial compartment and the clinical results of arthroscopic partial synovectomy. Type of Study: Retrospective case series. Methods: We treated 19 osteoarthritic knees with localized synovial hypertrophy in 19 patients by arthroscopic partial synovectomy under local anesthesia. All patients had complained of knee pain (mechanical type pain) and catching sensations preoperatively. Preoperative diagnosis based on physical findings and imaging studies was a medial meniscus tear with medial OA in all patients. The mean follow-up was 37 months (range, 28 to 46 months). Clinical results were assessed with the Hospital for Special Surgery (HSS) scoring scale, overall subjective estimation, and patient satisfaction. Results: The catching sensation resolved immediately after surgery in all patients. The mean HSS score improved from 56.8 to 72.4 points (P < .01). Nine patients (47.4%) were rated excellent or good according to the overall subjective estimation, and 11 patients (57.9%) were satisfied with the treatment. Both HSS score and patient satisfaction were higher in patients (10 patients) who complained of intraoperative pain during synovectomy than in those (9 patients) who hardly felt the pain. Conclusions: Localized synovial hypertrophy in the anteromedial compartment of OA knees occasionally caused symptoms of pain and catching sensations that resembled meniscal symptoms. Arthroscopic partial synovectomy was effective, especially for those who complained of intraoperative pain during synovectomy under local anesthesia. Level of Evidence: Level IV.