Bilateral Symptomatic Lateral Parapatellar Synovial Plica of the Knee in an Adolescent Athlete: A Case Report

We report herein a rare case of lateral parapatellar synovial plica that developed simultaneously in both knees. A 15-year-old competitive soccer player visited our institution with a six-month history of anterolateral pain and catching sensation in both knee joints. On physical examination, he complained of tenderness along the joint line of bilateral patellofemoral joint (PFJ). Visible and palpable popping was observed at the lateral margin of each patella during active knee motion. Magnetic resonance imaging showed obvious synovial soft nodules in the lateral side of the PFJ. On arthroscopy, a yellowish, thick, tongue-shaped tissue extending transversely from the lateral parapatellar synovium was identified in both knees, and parts of this tissue showed avascular hypertrophy. Arthroscopic findings of both knees are almost symmetrical in anatomical location, but no similar in size. After arthroscopic excision, the patient became asymptomatic. At 24-month follow up, he demonstrated full knee function, without evidence of local recurrence.