Pigmented villonodular synovitis of knee with concomitant partial tear of anterior cruciate ligament in skeletally immature patient: A case report

Pigmented villonodular synovitis (PVNS) is benign but locally aggressive proliferative disorder that affects synovial joint, tendon sheaths, and bursae. PVNS is rare in child, while concurrent Anterior Cruciate Ligament (ACL) tear in PVNS is uncommon finding. Previous study reported ACL tear might be a risk factor in adult PVNS but lack of record for pediatric PVNS. We report a case of uncommon concomitant ACL partial tear in an already rare pediatric PVNS. A nine-year old female with pain and swelling on left knee, occurred intermittent every 2 months for 1 year prior to surgery. There was moderate knee movement restriction with history of fall from bicycle 1 year before surgery. No history of knee instability was reported. X-ray only denote joint swelling, while MRI shows intraarticular bodies suspected synovial chondromatosis with hyperintense signal sign of partial ACL tear. The patient underwent arthroscopic evaluation which exhibit intraarticular hyperemic and hypertrophic synovium with loosening anteromedial ACL bundle. Arthroscopic synovectomy was then performed followed by range of motion training and muscle strengthening rehabilitation program. Post-operative histopathological result confirms PVNS assessment. 1 year follow up post-surgery shows no recurrence of pain or swelling with free movement of left knee joint and no disturbance or instability while walking. In this case, partial ACL tear may contribute as risk factor of PVNS in child. Arthroscopic synovectomy with physical rehabilitation program shows good functional result with no recurrence at 1-year follow up.