a post-traumatic cyclops lesion arising from posterior cruciate ligament injury with loss of extension: a case report

Introduction: cyclops lesions or arthrofibrotic nodules of the knee, first described by jackson and schaefer, occur in the anterior aspect of the intercondylar notch. arthroscopically, they appear as head-like fibrous lesions with reddish-blue discoloration areas and consist of a pedunculated nodule of fibrovascular proliferative tissue, with or without bone or cartilaginous tissue. the cyclops lesion is a localized arthrofibrotic nodule most commonly seen following anterior cruciate ligament (acl) reconstruction but rare on posterior cruciate ligament injuries (pcl). in this study, we present a novel case of cyclops lesion from a minor pcl injury without laxity or previous surgery. case presentation: a 37-year-old man visited the outpatient clinic complaining of mild knee pain, intermittent locking, and extension discomfort after minor trauma. these symptoms started 3 weeks prior, during his usual baseball activity. the magnetic resonance imaging (mri) showed an intact acl. still, it had a partially injured pcl, a small suprapatellar effusion, and a cyclops lesion (2.4 × 3.4 × 2.5 cm) in the intercondylar notch of the femur, originating from the pcl. an arthroscopy confirmed and excised a cyclops lesion originating from the pcl. the microscopic findings included congested blood vessels of irregular-sized veins and hemorrhagic necrosis within the wavy ligament tissues, which confirmed its origin from the ligament tissue. after arthroscopic excision, the patient’s symptoms were relieved without laxity. conclusions: while most of these lesions can be treated efficiently by arthroscopy, the differential diagnosis should be performed for unique cases with a lesion from minor pcl injury without laxity or previous surgery.