Anterior Cruciate Ligament Ganglion Cyst and Mucoid Degeneration: A Review

Mucoid degeneration and ganglion cyst are two distinct non-traumatic lesions of the anterior cruciate ligament (ACL) that most commonly occur discretely but occasionally coexist. They are relatively uncommon, and their exact aetiopathogenesis is still not clear. ACL ganglion cyst occurs more frequently among relatively younger patients compared to mucoid degeneration. They could be asymptomatic and discovered incidentally while evaluating the knee for other pathologies. Symptomatic cases of the two conditions present with nonspecific chronic pain, painful limitation of terminal flexion and extension, and mechanical block (among other symptoms), similar to that of other internal derangement pathologies of the knee. Magnetic resonance imaging is the investigation of choice, and diagnostic criteria are defined. Arthroscopic management of these conditions efficiently provides an improvement in symptoms without instability. Computed tomography scan guided aspiration is also useful in selected cases of ACL ganglion cyst. ACL ganglion cyst and mucoid degeneration should be considered in the differential diagnosis of chronic knee pain and stiffness of unspecified etiology.