Anterior Cruciate Ligament Ganglion Cyst: Uncommon Cause of Knee Pain

Purpose: Anterior cruciate ligament (ACL) ganglion cysts are rare intra-articular lesions, particularly uncommon in the pediatric population. This report describes a symptomatic ACL ganglion in a child, detailing clinical presentation, imaging findings, arthroscopic management, and postoperative outcome, and reviews the current literature. Methods: We present the case of a 7-year-old male with a 3-month history of progressive right knee pain, culminating in extension block. Clinical examination revealed a 10° extension deficit without instability or swelling. Magnetic resonance imaging (MRI) demonstrated an intrasubstance ganglion cyst within the proximal and middle thirds of the ACL, associated with partial fiber disruption. Arthroscopic resection and aspiration of the cyst were performed, followed by a structured rehabilitation program. Results: Arthroscopy confirmed a ganglionic lesion attached to the ACL walls, with intact menisci and no other intra-articular pathology. Complete cyst excision was achieved without complications. At 3-month follow-up, the patient was pain-free, had regained full range of motion and strength, and returned to sports activities. Conclusion: Although rare in children, ACL ganglion cysts should be considered in the differential diagnosis of pediatric knee pain with unexplained motion restriction. MRI is the diagnostic modality of choice, and arthroscopic resection offers an effective and definitive treatment with excellent functional recovery.