Advanced arthroscopic management of diffuse knee synovial chondromatosis with large tricompartmental nodules using trans-notch visualization and a safe posteromedial portal

Introduction: Synovial chondromatosis of the knee is a rare, intermediate (locally aggressive) disorder that may present as a diffuse disease with large nodules, which is particularly challenging when the posterior compartment and retrocruciate space are involved, as the proximity to the neurovascular bundle limits standard arthroscopic access. Case presentation: A 37-year-old woman presented with a 5–6-year history of progressive right knee pain, recurrent mechanical locking, spontaneous effusions, severe stiffness, and muscle atrophy. Range of motion showed a 12° extension deficit and flexion limited to 80°. Plain radiographs demonstrated multiple intra-articular calcifications, and magnetic resonance imaging revealed diffuse synovitis with chondromatous micronodules and three giant loose bodies (anterior, intercondylar, and retrocruciate). The condition was classified as primary synovial chondromatosis, Milgram stage III. The patient underwent comprehensive arthroscopic treatment using anterior portals, trans-notch visualization, and a safe posteromedial portal, achieving complete removal of the three giant bodies without posterior capsulotomy and with intact cartilage, menisci, and ligaments. Clinical discussion: Tricompartmental involvement with retrocruciate giant loose bodies is exceptional and has traditionally been considered an indication for open surgery. A systematic arthroscopic strategy, combining trans-notch visualization with a precisely planned posteromedial portal, widens the visual field, addresses blind areas in the posterior compartment, and enables mobilization of firmly adherent masses while minimizing neurovascular risk. Targeted synovectomy of inflamed areas may help reduce recurrence. Conclusion: Advanced arthroscopic management, integrating trans-notch visualization and a safe posteromedial portal, allowed effective treatment of diffuse knee synovial chondromatosis with large tricompartmental nodules, avoiding extensive arthrotomies and achieving a satisfactory functional outcome without clinical or radiological recurrence at the 4-year follow-up.