Introduction: It has been proposed that tunnel widening in ACL reconstructions is due to excessive graft tunnel motion secondary to elastic fixation.

Aim: To determine whether techniques which fix the graft closer to the joint (interference screws), eliminate the bungy cord and are stiffer will decrease tunnel widening. The clinical significance of tunnel widening is examined.

Method: Two hundred and fifty nine patients were evaluated prospectively. Four fixation methods were evaluated. Sixty-nine were reconstructed using Endobuttons and staples (elastic fixation). Forty-eight were subjects reconstructed with a bone mulch screw and staples, 55 patients were reconstructed with metal interference screws and 87 with bioabsorbable interference screws. Patients underwent a clinical examination, IKDC, Cincinnati knee score and KT-1000 testing one year post-operatively. These factors were correlated with tunnel widening. Tunnel widening was determined using magnification adjusted AP and lateral radiographs using Scion Image software.

Results: Tunnel widening occurred with all the fixation methods. Mean tunnel area increased 122% for the Bioscrew, 89% for the metal interference screw, 76% for the bone mulch screw and 36% for the Endobutton (ANOVA p=< 0.0001). Tunnel widening did not correlate with increased laxity, poor IKDC or Cincinnati knee scores.

Conclusions: Tunnel widening occurred with both elastic and rigid fixation methods. Tunnel widening could not be avoided by fixing the graft closer to the joint or eliminating the ‘bungy cord’. Graft tunnel motion was not the sole cause of tunnel widening in ACL reconstruction. Tunnel widening did not correlate with poor outcome in the short term.