Biomechanical comparison of interference screw and cortical button with screw hybrid technique for distal biceps brachii tendon repair

Various fixation techniques have been described for ruptured distal biceps tendons. The authors hypothesized that no significant differences would be found between the mean failure strength, maximum strength, and stiffness of the interference screw and hybrid technique. Fourteen fresh-frozen human cadaveric elbows were prepared. Specimens were randomized to either interference screw or hybrid cortical button with screw fixation. The tendon was pulled at a rate of 4 mm/s until failure. Failure strength, maximum strength, and stiffness were measured and compared. Failure strength, maximum strength, and stiffness were 294±81.9 N, 294±82.1 N, and 64.4±40.5 N/mm, respectively, for the interference screw technique and 333±129 N, 383±121 N, and 56.2±40.5 N/mm, respectively, for the hybrid technique. No statistically significant difference existed between the screw and hybrid technique in failure strength, maximum strength, or stiffness (P>.05). The interference screws primarily failed by pullout of the screw and tendon, whereas in the hybrid technique, failure occurred with screw pullout followed by tearing of the biceps tendon. The results suggest that this hybrid technique is nearly as strong and stiff as the interference screw alone. Although the hybrid technique facilitates tensioning of the reconstructed tendon, the addition of the cortical button did not significantly improve the failure strength of the interference screw alone.