--- title: Cyclops Lesion - ProScan Education description: Cyclops lesions are typically the result of complications in the reconstruction of an anterior cruciate ligament (ACL). Also referred to as localised anterior arthrofibrosis, this fibrous anterior knee mass is a common cause of extension loss. --- # Dr. Pomeranz's Ultimate Guide to : ## MRI of the Knee ## **Cyclops Lesion**   Cyclops lesions are typically the result of complications in the reconstruction of an anterior cruciate ligament (ACL). Also referred to as localized anterior arthrofibrosis, this fibrous anterior knee mass2 is a common cause of extension loss. Predisposing factors include “non-isomeric” or abnormal graft tunnel placement, small or dysplastic femoral notch, and unrecognized injuries of other ligaments.       ## **Cyclops Lesion: Clinical Presentation** Extension of the repaired knee results in pain to the patient. Within 8 to 32 weeks of ACL repair, the patient may experience an audible and palpable “clunk”. Post ACL reconstruction, cyclops lesions are estimated to occur in approximately 5% of patients. 1   ## **Cyclops Lesion: Pathology** Though the pathophysiology in not completely certain, the possible reasons could be:   - Fraying of remnant ACL fibres - Excessive fibrosis - Uplifting of fibrocartilaginous tissue during ACL reconstruction 2   ## **Cyclops Lesion: MRI** In all pulse sequences, the signal intensity of a cyclops lesion is intermediate to low. This is due to the fibrous structure of the lesion. Close to the tibial insertion of the reconstructed ACL, a mass such as this one is located anteriorly / anterolaterally in the intercondylar notch. 2   ## **Cyclops Lesion: Treatment** Typically, arthroscopic excision is recommended. 2   ## Cyclops Lesion: References 1. Runyan BR, Bancroft LW, Peterson JJ et-al. Cyclops lesions that occur in the absence of prior anterior ligament reconstruction. Radiographics. 27 (6): e26. 2. Weerakkody Y., Gaillard F., et-al. Cyclops Lesion (Knee): Radiopaedia (sourced 10Jan2018): [https://radiopaedia.org/articles/cyclops-lesion-knee](https://radiopaedia.org/articles/cyclops-lesion-knee)     ## **Cyclops Lesion: Example** *[Click here to launch this case](http://cases.proscan.com/288492902264)* ** ** ### **HISTORY:** Knee pain. No injury.   ![axial t2 fse](https://info.medality.com/hs-fs/hubfs/Project%20Cerebro%20(All%20images)/image72.png?width=250&height=250&name=image72.png)    ![sagittal t2 fse](https://info.medality.com/hs-fs/hubfs/Project%20Cerebro%20(All%20images)/image28.png?width=250&height=250&name=image28.png) ** ****  ** **Image 1 - Axial T2 FSE                      Image 2 - Sagittal T2 FSE** ** **       ### **FINDINGS:** - No microtrabecular or macrotrabecular fracture. - Slightly laterally displaced patella. Massive induration of Hoffa fat pad. - No high-grade chondromalacia of the patellofemoral compartment. - Flexors and extensors are intact. - Partial-thickness chondral thinning of the weight bearing medial femoral condyle. Minimal marginal spurring medial femoral condyle. Stable healing complex vertical tear in the outer red-red zone posterior horn to posterior body of the medial meniscus likely from original pivot-shift injury. - PCL is intact. ACL graft is intact. Giant **cyclops lesion** (images 1 and 2, green arrows) anterior to the ACL graft favored over localized PVNS (also known as giant cell tumor of tendon sheath, intra-articular). - MCL and LCL are intact. - No high-grade chondromalacia of the lateral compartment. Minimal marginal spurring lateral femoral condyle. No lateral meniscus tear. - Posterolateral corner is intact. - 2+ proteinaceous effusion. - Swelling of the subcutaneous tissues anteriorly. ** ** ### **CONCLUSION:** - ACL graft is intact with giant cyclops lesion anterior to the ACL graft favored over localized PVNS. - Stable healing complex vertical tear outer healing red-red zone posterior horn to posterior body of the medial meniscus likely from original pivot-shift injury.   * *   ## **Table of Contents**  [Clinical Presentation](https://info.medality.com/cyclops-lesion#Cyclops%20Lesion:%20Clinical%20Presentation) [Pathology](https://info.medality.com/cyclops-lesion#Cyclops%20Lesion:%20Pathology) [MRI](https://info.medality.com/cyclops-lesion#Cyclops%20Lesion:%20MRI) [Treatment](https://info.medality.com/cyclops-lesion#Cyclops%20Lesion:%20Treatment) [References](https://info.medality.com/cyclops-lesion#Cyclops%20Lesion:%20References) [Example](https://info.medality.com/cyclops-lesion#Cyclops%20Lesion:%20Example) [![Explore MRI Online's MSK Imaging Courses](https://no-cache.hubspot.com/cta/default/4177793/e30972f9-1305-47ab-8629-838627df4437.png)](https://cta-redirect.hubspot.com/cta/redirect/4177793/e30972f9-1305-47ab-8629-838627df4437) [![View Courses](https://no-cache.hubspot.com/cta/default/4177793/4b4ae251-ef8e-4c9d-8bea-ec59f19899e8.png)](https://cta-redirect.hubspot.com/cta/redirect/4177793/4b4ae251-ef8e-4c9d-8bea-ec59f19899e8) - [**](https://www.facebook.com/proscaneducation/) New MRI Cases Sent Weekly ### About Us We're on a mission to bring the best online MRI education to the world's radiologists ### Office 5400 Kennedy Ave. Cincinnati, OH 45202 ### Contact Us M-F 8AM-5PM EST +1 866-MRI-EDUC (866-674-3382) support@medality.com ### Latest Cases to Review © 2018 [Medality / MRI Online](https://medality.com/) [Terms of Use](https://medality.com/terms/) | [Privacy Policy](https://medality.com/privacy-policy/) ** google-site-verification=ecoazcFTJuw2sjsuFaHY5TQ03ZyOnJrReauQoQP4DBI