Arthroscopic treatment of cyclops nodule after rupture of the anterior cruciate ligament

Background
Cyclops nodule can develop after anterior cruciate ligament (ACL) injury. It can lead to loss of full knee extension with development of an audible and palpable ‘clunk’ with terminal extension.
Patients and methods
Sixteen patients presented with persistent lack of full knee extension after torn ACL. All patients were subjected to rehabilitation with emphasis on knee extension for 6 weeks after presentation. Persistent lack of full extension despite aggressive rehabilitation was an indication for arthroscopic resection of the cyclops nodule. At arthroscopy, a cyclops nodule was found impinged in the intercondylar notch and acted as a mechanical block to full knee extension. After arthroscopic resection of the nodule under spinal anesthesia, the knee was manually manipulated to regain full knee extension. Physical therapy exercises were then prescribed to obtain and maintain full extension.
Results
Full knee extension was achieved for 12 (75%) patients at the time of the surgical procedure. After 2 years of follow-up, all patients achieved full range of knee motion with no complications.
Conclusion
It is important to recognize a cyclops nodule as a possible cause of extension loss in any patient with ACL injury. It is readily amenable to arthroscopic resection and good patient outcome.