PURPOSE

This study investigated background factors and bone tunnel location related to cyclops lesions and knee extension loss after anterior cruciate ligament (ACL) reconstruction, and the relationship between cyclops lesions and postoperative muscle strength changes.

METHODS

This study included 192 patients (101 male and 91 female patients, mean age of 27.9 years [range, 13-70 years]) who had undergone ACL double-bundle reconstruction and had cyclops lesions evaluated by magnetic resonance imaging or second-look arthroscopy. The bone tunnel position was measured using computed tomography, and knee extension limitation was measured postoperatively. Knee extension and flexion strength was measured preoperatively and postoperatively. Differences between the cyclops and no-cyclops groups were analyzed.

RESULTS

The presence of cyclops lesions was significantly associated with a shallower femoral bone tunnel of the posterolateral bundle (p = 0.03). In the presence of a cyclops lesion, the higher position of the femoral bone tunnel of the anteromedial bundle (p = 0.01) and the posterior location of the tibial bone tunnel (p = 0.048) cause extension limitation. There was no difference in knee extension strength between the cyclops and no-cyclops groups preoperatively (p = 0.73), and the postoperative differences at 4, 6, 9,12 months (each p < 0.05) were significantly larger, with the cyclops group having lower values than the no-cyclops groups. There was no significant difference in knee flexion strength (p > 0.05).

CONCLUSION

Bone tunnel position and graft size are associated with the formation of cyclops lesions, and subsequent extension loss and cyclops lesions are related to weakness in extension strength one year after ACL reconstruction.