MR Imaging of Cyclops Lesions

Abstract

MR imaging was sensitive, specific, and accurate in revealing cyclops lesions in a subgroup of patients with extension loss after ACL reconstruction.

T2 black lesions on routine knee MRI: differential considerations

“…The lesions are so called because of their bulbous, head-like appearance with reddish-blue discoloration that resembles an 'eye' on arthroscopy. MRI of cyclops lesions shows a well-circumscribed nodule anteriorly or anterolaterally in the intercondylar notch and posterior to the infrapatellar fat pad, with intermediate to low signal intensity on all pulse sequences [54,62]. Diffuse arthrofibrosis, on the other hand, engulfs the graft extending anteriorly, between the graft and the infrapatellar fat pad, and posteriorly between the ACL graft and the joint capsule [61].…”

Analysis of cyclops lesions after different anterior cruciate ligament reconstructions: a comparison of the single-bundle and remnant bundle preservation techniques

“…Typically, MR images show an intermediate signal intensity lesion located anterior to an ACL graft and the lesion extends anteriorly to a line along the intercondylar roof. In previous studies, the sensitivity (85.0%), specificity (84.6%), and accuracy (84.8%) of MRI were found to be high in patients with persistent symptoms after ACL reconstruction [10].…”

“…They are a localized form of anterior fibrosis, and these cyclops lesions are an important cause of partial knee extension loss after ACL reconstruction. The potential origins of cyclops lesions are a residual tibial ACL stump, a tibial tunnel trapdoor, infrapatellar fat pad metaplasia, intercondylar fibrosis, or the graft itself [10]. Symptomatic cyclops lesions are reported in 0-2% of patients after ACL reconstruction [3,10,20,21], and these lesions are amenable to arthroscopic resection.…”

“…Their characteristic clinical findings include a rubbery end point at full extension with or without a palpable pop, a rebound after manipulation into full extension and an initial full range of motion that is subsequently lost [10]. However, these findings are variable and unreliable.…”

“…However, in the remnant bundle preservation technique, the remnant bundle is located anterior along the ACL graft, and so it can mimic a cyclops lesion. Moreover, the residual tibial ACL stump can be a source of cyclops lesion [10]. To the best of our knowledge, no previous study has compared the prevalence and imaging findings of a cyclops lesion after these surgical techniques.…”