Biomechanical comparison of different fixation techniques for reconstruction of tibial avulsion fractures of the anterior cruciate ligament.

PURPOSE

The most common fixation techniques for tibial avulsion fractures of the anterior cruciate ligament (ACL) described in the literature are screw and suture fixation. The fixation of these fractures with the TightRope® device might be an alternative. Up to now it has been commonly used in other injuries, such as acromioclavicular joint or syndesmosis ruptures. The purpose of this study was to evaluate the biomechanical properties of different fixation techniques for the reconstruction of tibial avulsion fractures.

METHODS

Type III tibial avulsion fractures were simulated in 40 porcine knees. Each specimen was randomly assigned to one of four groups: (1) anterograde screw fixation, (2) suture fixation, (3) TightRope® fixation or (4) control group. The initial displacement, strength to failure and the failure mode were documented.

RESULTS

The maximum load to failure was 1,345 ± 155.5 N for the control group, 402.5 ± 117.6 N for the TightRope® group, 367 ± 115.8 N for the suture group and 311.7 ± 120.3 N for the screw group. The maximum load to failure of the control group was significantly larger compared to all other groups. The initial dislocation was 0.28 ± 0.09 mm for the control group, 0.55 ± 0.26 mm for the TightRope® group, 0.84 ± 0.15 mm for the screw group and 1.14 ± 0.9 mm for the suture group. The initial dislocation was significantly larger for the suture group compared to the TightRope® and control groups.

CONCLUSIONS

The TightRope® fixation shows significantly lower initial displacement compared to the suture group. The TightRope® fixation might be an alternative for the repair of ACL tibial avulsion fractures that can be used arthroscopically.