Biomechanical Comparison of a Novel Tibial Fixation Technique Versus Interference Screw Fixation for ACL Reconstruction Using Soft Tissue Grafts

BACKGROUND: Controversy remains regarding the optimal technique for tibial fixation of soft tissue grafts in anterior cruciate ligament (ACL) reconstruction. PURPOSE/HYPOTHESIS: To compare the biomechanical outcomes of a novel transtibial tubercle fixation technique with those of a commonly utilized interference screw fixation at the tibial site. Our hypothesis was that transtibial tubercle fixation achieves higher ultimate failure loads than interference screw fixation. STUDY DESIGN: Controlled laboratory study. METHODS: We used 24 matched porcine tibias and digital extensor tendons, from which 12 grafts and tibial tunnels were prepared using the novel transtibial tubercle fixation technique and 12 were prepared using the interference screw fixation technique. The specimens underwent a cyclic loading test (50-250 N applied for 1000 cycles at a frequency of 1 Hz), followed by a load-to-failure test. The slippage, stiffness, and ultimate failure loads were compared between the techniques. RESULTS: No differences in slippage were found during the cyclic loading test, and no graft fixation or tibial complex failures occurred during cyclic testing in either group. The transtibial tubercle fixation technique had higher ultimate failure loads (mean ± SD, 756.28 ± 123.43 N) as compared with interference screw fixation (602.15 ± 81.62 N; P < .05). The grafts in the transtibial tubercle fixation group were less stiff than those in the interference screw fixation group (84.43 vs 101.23 N/mm; P < .05). CONCLUSION: Transtibial tubercle fixation achieved higher ultimate failure loads than interference screw fixation in the load-to-failure test. CLINICAL RELEVANCE: The novel transtibial tubercle fixation technique compared favorably with interference screw fixation during ACL reconstruction. This technique does not require hardware, has a low cost, theoretically eliminates the risk of complications associated with hardware implantation (eg, graft damage and pain attributed to retained hardware requiring removal), and is relatively easy to perform.