Progressive Loss of Knee Extension after Injury

Abstract

Cyclops syndrome has been defined as a loss of knee extension due to impingement of a pedunculated proliferative tissue mass after anterior cruciate ligament reconstruction. We describe four patients who were operated on for progressive loss of knee extension after minor knee injury. During the arthroscopic procedure, the consistent finding was a fibrous pedunculated nodule adhering to the anterolateral aspect of the original anterior cruciate ligament, obstructing extension by impingement in the anterior aspect of the knee. At least part of the anterior cruciate ligament was intact in all cases. These patients were compared with seven patients who developed cyclops syndrome after anterior cruciate ligament reconstruction. Clinical and arthroscopic findings were the same in both groups. An arthroscopic excision of the nodule, performed an average of 12 weeks after knee trauma or after reconstruction, gave very good results. Histologic examination of the excised nodules from both groups showed fibroelastic connective tissue proliferation, thromboangiitis, and areas of necrotic bone and foreign body giant cell granuloma. On the basis of our observations, we conclude that formation of a fibrous pedunculated nodule may occur after an anterior cruciate ligament injury as well as after surgical reconstruction of the anterior cruciate ligament.

Cyclops lesions detected by MRI are frequent findings after ACL surgical reconstruction but do not impact clinical outcome over 2 years

“…No revision surgeries were performed in the period evaluated by our study. The “cyclops syndrome” [8,18] has been described as very rare (0–2%) and most of the symptomatic cases with extension loss are reported in the literature within the first two years after surgery. Therefore, we were not surprised that there was no patient in our cohort that had to undergo surgery because of a cyclops lesion.…”

“…Arthroscopic studies have estimated the prevalence of symptomatic cyclops lesions after ACL surgery ranging between 1% and 9.8% [16, 17]. Symptomatic cyclops lesions, also referred as cyclops syndrome [8, 18], are treated by arthroscopic removal with eventually an additional notchplasty, regaining the full extension of the knee [19–22]. …”

Stump Entrapment of the Torn Anterior Cruciate Ligament

“…Cyclops lesions are a recognized complication of ACL reconstruction surgery and much like ACL stump entrapment, cause an inability to fully extend the knee because of a nodular mass of granulation tissue that extends into the anterior joint compartment [4, 6]. As in ACL stump entrapment, the lesion lies in the intercondylar notch between the tibial plateau and the femoral condyle [7].…”

“…Stump entrapment of the ACL causes a pseudo-cyclops lesion, albeit similar in appearance and presentation to the cyclops lesion seen following ACL repair [1, 2, 4, 6, 7]. Although this entity is rare, proper understanding and recognition are imperative for prompt surgical resection.…”

Sonographic and Magnetic Resonance Imaging Examination of a Cyclops Lesion After Anterior Cruciate Ligament Reconstruction: A Case Report

“…Cyclops lesions are proliferative fibrous nodules with neovascularity that may be a complication of anterior cruciate ligament (ACL) reconstructions or, rarely, acute ACL injury without reconstruction. [1][2][3][4][5][6][7][8][9][10][11][12] The etiology of these nodules is multifactorial, including iatrogenic bone and cartilage drilling debris or anteriorly positioned graft, ACL stump remnants, partially torn anterior graft fibers, and graft hypertrophy from chronic impingement. 1,2,4 Patients often present with medial joint line pain and loss of full extension of the knee, 1,2,4-10 suggesting cyclops syndrome.…”