Introduction

Revision anterior cruciate ligament (ACL) reconstruction may be complicated by graft tunnel osteolysis, often requiring a two-stage procedure with initial bone grafting followed by definitive ligamentous reconstruction at a later date. This cadaveric study aimed to compare the biomechanical properties of an over-the-top (OTT) femoral fixation technique that does not require bone tunnels to the conventional single-bundle technique for ACL reconstruction. We hypothesized that the OTT technique would be biomechanically non-inferior to the conventional technique.

Methods

Eight matched pairs of cadaveric knees were used. Specimens in each pair were randomized to undergo either a conventional single-bundle ACL reconstruction with femoral and tibial bone tunnels or an OTT technique with extra-physeal fixation on the femoral side. An ACL rupture was simulated by transecting the ligament arthroscopically. All reconstructions were performed using a quadruple-strand hamstring autograft. Specimens were mounted onto a custom biomechanical testing jig, which held the femur in place and applied a 134N anterior force to the tibia with the knee flexed to 30 degrees. Displacement of the tibia relative to the femur was recorded and compared between groups using paired t tests.

Results

No significant difference in mean anterior tibial displacement was observed between the intact and reconstructed states for the control (6.19 vs. 7.13mm; p=0.41) or experimental (6.25 vs. 6.03mm; p=0.71) reconstruction techniques. Similarly, there was no significant difference in mean displacement observed between the reconstructed experimental specimens and reconstructed controls (6.03 vs. 7.13mm; p=0.28).

Conclusions

ACL reconstruction using an OTT femoral fixation technique demonstrated no significant difference in anterior tibial displacement compared to conventional single-bundle reconstruction. These data suggest that a single-stage reconstruction using OTT femoral fixation may be a biomechanically viable alternative to avoid a two-stage revision procedure in the setting of ACL graft failure with femoral tunnel osteolysis.