A cyclops lesion is known as anterior arthrofibrosis, and is a post surgical complication of anterior cruciate ligament reconstruction that leads to limited knee extension range of motion. It is called a cyclops because the nodule of fibers looks like an eye.
Cyclops lesions have been reported after complete and partial ACL tears. Microtrauma following injury leads to the formation of the nodule and has been found following different types of ACL grafts and reconstruction types. Research has found cyclops lesions to be more common in double-bundle and quadriceps grafts compared to single-bundle and hamstring grafts. This may be due the larger volume of the graft impinging in the knee join
Causes:
Microtrauma to the graft following surgery e.g. slip, trip or fall
Hypertrophied or enlarged graft
More common in double bundle graft than single bundle graft
Can be due to the larger bunching of the graft impinging in the joint
More anterior placed tibial tunnel in surgery
Symptoms:
Patients with symptomatic cyclops lesions (known as cyclops syndrome) often demonstrate loss of terminal knee extension, report discomfort with walking/running/lying supine, and have an audible or palpable clunk during terminal knee extension. Other common symptoms include unresolved swelling after reconstruction surgery and locking of the knee. The most common clinical sign is loss of knee extension (straightening knee) post-operatively.
Management:
Unfortunately Physiotherapy can not structurally change a cyclops lesion, however we can recognise one may be present and alert the surgeon. For symptomatic cyclops lesions, arthroscopic surgical debridement of the lesion can restore normal biomechanics of the knee. Patients typically have good prognosis of recovering function and full knee range of motion following excision surgery. After debridement of the cyclops lesion, Physiotherapy can continue rehabilitation as per normal, following the Foundation Clinic ACL Protocol.
