Cyclops lesions are nodular structures that form anteriorly along anterior cruciate ligament (ACL) grafts after ACL reconstruction. The purpose of this study was to investigate the occurrence rate and pathogenesis of cyclops lesions after reconstruction of the ACL. We evaluated 40 patients by follow-up arthroscopy after anatomical bi-socket ACL reconstruction with hamstring tendons. Ten patients (25%) showed cyclops lesions, and 4 of these (10%) had extension loss.
We investigated the pathogenesis of cyclops lesion based on the impingement theory. All patients underwent measurement of intercondylar notch dimensions and graft size by MRI. We found that a narrower notch and larger graft size were associated with the formation of cyclops lesion.