What is the diagnosis and treatment of a cyclops lesion in the knee?

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Last updated: April 17, 2025View editorial policy

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From the Research

Arthroscopic removal of the cyclops lesion is the most effective treatment for cyclops syndrome, allowing for full range of motion and improved function, as evidenced by the most recent study in 2022 1. The cyclops lesion is a known complication of anterior cruciate ligament reconstruction (ACLR) that can cause loss of knee extension, pain, and impaired function. Key characteristics of cyclops lesions include:

  • Formation of a scar tissue nodule adjacent to the tibial tunnel of the ACL graft
  • Loss of knee extension range of motion (ROM)
  • Pain and impaired function
  • Typically diagnosed using magnetic resonance imaging (MRI) Treatment options for cyclops lesions include:
  • Arthroscopic debridement, which has been shown to be effective in gaining symmetrical knee extension range of motion and improved function 2
  • Conservative management for asymptomatic lesions
  • Surgical excision for symptomatic lesions, which can result in resolution of symptoms and improved knee extension 3 The rehabilitation protocol after surgery typically includes:
  • Range-of-motion exercises
  • Progressive strengthening
  • Gradual return to activities over 4-6 weeks Early recognition and treatment of cyclops lesions are crucial to prevent long-term knee stiffness and functional limitations. If you experience persistent inability to fully straighten your knee after ACL reconstruction, especially with pain at the end range of extension, consult your orthopedic surgeon promptly for evaluation. Recent studies have also explored the use of minimally invasive approaches, such as the NanoScope, for the excision of cyclops lesions, which may offer decreased postoperative pain and swelling, and a quicker recovery 1. Overall, the treatment of cyclops lesions should prioritize the restoration of full knee extension and strength, and the prevention of long-term functional limitations, as supported by the evidence from recent studies 4, 5.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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