Cyclops Lesions of the Knee: A Narrative Review of the Literature

Cyclops lesion is a known complication of anterior cruciate ligament reconstruction (ACLR). Although the incidence of cyclops lesion appears to be decreasing, it remains an important cause of restriction of extension after ACLR. We reviewed the available literature regarding the cyclops lesion and syndrome and cyclops-like lesions to analyze available evidence on cyclops lesions and variants of cyclops lesions. A keyword search in PubMed, Scopus, Web of Science, and EMBASE, Ovid Medline, and Ovid journals provided 47 relevant articles in the English literature, which were used to create this review. We classified cyclops lesions based on clinical presentation, pathology, and location. Risk factors, management options, tips to reduce the condition, and controversies related to the condition have been discussed. Female sex, greater graft volume, bony avulsion injuries, excessively anterior tibial tunnel, double-bundle ACLR, and bicruciate-retaining arthroplasty appear to predispose patients to cyclops lesions. Cyclops syndrome is a cyclops lesion that causes a loss of terminal extension. Arthroscopic debridement is an effective treatment for cyclops syndrome, whereas cyclops lesions are usually managed conservatively. It is important to distinguish between cyclops lesion and cyclops syndrome, as management differs based on symptoms. Cyclops lesion is diagnosed using magnetic resonance imaging. The management of choice for symptomatic lesions is surgical excision. Outcomes after excision are very good, and recurrence is rare.