Introduction: Tophaceous gout rarely manifests within intra-articular structures of the knee, and involvement of cruciate ligaments is exceptionally uncommon. Such atypical presentations frequently simulate degenerative or cystic ligament pathology on magnetic resonance imaging (MRI), leading to diagnostic delay and inappropriate preoperative diagnosis.

Case Report: A 30-year-old male with chronic kidney disease and hyperuricemia presented with painful hyperflexion of the knee and difficulty in sitting cross-legged. Clinical examination revealed stable Lachman with a doubtful end point, negative anterior and posterior drawer tests, and absence of joint line tenderness. MRI suggested mucoid degeneration of the anterior cruciate ligament. Diagnostic arthroscopy revealed extensive chalky white tophaceous deposits diffusely involving the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), synovium, and articular cartilage. Arthroscopic debridement and debulking were performed. The patient experienced significant pain relief postoperatively and regained comfortable cross-legged sitting by 15 days.

Conclusion: Intra-articular tophaceous gout involving cruciate ligaments is a rare diagnostic masquerader. Arthroscopy remains the definitive diagnostic and therapeutic modality. Gout should be considered in patients with atypical intra-articular knee pathology, especially in the presence of hyperuricemia and renal disease.