MR imaging of cyclops lesions

OBJECTIVE. Localized anterior fibrosis (cyclops lesion) is a known cause of extension loss of the knee after anterior cruciate ligament (ACL) reconstr uction. We describe MR imaging as a noninvasive diagnostic tool to examine cyclops lesions. SUBJECTS AND METHODS. Thirty-three MR studies of 31 patients with residual persistent extension loss after ACL reconstruction using patellar tendon au tograft were reviewed and compared with results of second arthroscopy. We u sed MR imaging to describe the ACL graft signal intensity and course, tibia l and femoral tunnel placement, quantitative measurements of notch size and shape, and the presence or absence of cyclops lesions. When a cyclops lesi on was revealed on MR imaging, the signal-intensity characteristics, locati on, and size were documented. Preoperative MR imaging findings were then co rrelated with findings at arthroscopy, RESULTS. The sensitivity, specificity, and accuracy of revealing a cyclops lesion on MR imaging were 85.0%, 84.6%, and 84.8%, respectively, We found n o statistically significant differences in the size of intercondylar notche s for patients with and patients without cyclops lesions. CONCLUSION. MR imaging was sensitive, specific, and accurate in revealing c yclops lesions in a subgroup of patients with extension loss after ACL reco nstruction.