A cyclops lesion is a bunched up area of scar tissue in the notch of the femur, usually seen as a complication of anterior cruciate ligament reconstruction.

Page updated September 2023 by Dr Sheila Strover (Clinical Editor)

cyclops lesion after ACL reconstruction

A cyclops lesion filling the notch of the femur anterior to the reconstructed anterior cruciate ligament (ACL).

cyclops cartoon

The original cyclops of mythology was a one-eyed monster.


Extension deficit as a result of a cyclops lesion

The bunched up tissue causes problems with achieving full extension. There may be a complete inability to achieve full extension, or it may be possible with an uncomfortable clunk.

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What cause a cyclops lesion

The problem may be triggered by doing the ACL reconstruction too early, when there is still inflammation in the area. In these circumstances the presence of bone debris can trigger the arthrofibrotic process.

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Forum discussions

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Peer-reviewed papers

  • Quote:

    Recommended strategies to prevent cyclops lesions include...."

    • Delaying ACLR until after recovery of ROM

    • Minimally invasive surgery compared with open ACLR

    • Creating less debris by use of a sequential reamer and thorough removal of debris

    • Correct tunnel positioning

    • Debridement in and around the bone tunnel"

    Citation: Kambhampati SBS, Gollamudi S, Shanmugasundaram S, Josyula VVS. Cyclops Lesions of the Knee: A Narrative Review of the Literature. Orthop J Sports Med. 2020 Aug 28;8(8):2325967120945671. doi: 10.1177/2325967120945671. PMID: 32923503; PMCID: PMC7457408.

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localised anterior arthrofibrosis

Dr Sheila Strover (Editor)
BSc (Hons), MB BCh, MBA

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