Cyclops Lesion

A cyclops lesion, its name deriving from its resemblance to an eyeball at arthroscopy, is a complication of ACL repair. It is also known as localized anterior arthrofibrosis, and its exact aetiology is uncertain, and may be related to gradual fraying and bunching up of ACL or graft fibres, excessive fibrosis, or even as a result of tissue fragments released from drilling. The end result, regardless of cause, is a rounded fibrous ball sitting in the intercondylar notch. (see annotated image). When symptomatic the knee has difficulty fulling extending and is painful when attempts are made. Treatment is by arthroscopic excision.
For a picture of a cyclops, please visit Radiopaedia.org here.
Reference: T. R. McCauley “MR Imaging Evaluation of the Postoperative Knee” Radiology 2005;234:53-61
Credit: Dr Frank Gaillard
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