Biomechanical evaluation of distal biceps reconstruction with cortical button and interference screw fixation

Hypothesis: Tension slide repair maintains the strength of the standard cortical button repair but reduces gap formation at the repair. Distal biceps tendon repair with a suspensory cortical button has yielded the strongest published repair, despite observed gap formation and tendon pistoning. The tension slide technique (TST) was described to reduce gap formation while maintaining the strength of cortical button repair. This study evaluates the biomechanics of the TST compared with previously described EndoButton (Smith & Nephew, Memphis, TN) repair and the TST with and without an interference screw. Materials and methods: The study used 20 matched specimens: 5 had a standard cortical button repair, and 5 had biceps repair with the TST. An additional 10 specimens underwent a TST, 5 with an interference screw and 5 without. All were cyclically loaded for 3600 cycles. Gap formation and load to failure were measured. Results: The mean (SD) load to failure for standard technique was at 389 (148) N vs 432 (66) N for the TST (P=.28). The mean (SD) gap formation was 2.79 (1.43) mm with the standard repair and 1.26 (0.61) mm with the TST (P=.03). The mean (SD) load to failure with TST repair was 436 (103) N without the interference screw and 439 (94) N (P=0.48) with the screw. The mean gap formation was 1.63 (1.09) mm without the screw and 1.45 (0.67) mm with the screw (P=.38.) Conclusion: This TST maintains the strength of the standard cortical button repair, but significantly reduces gap formation and motion at the repair site.