Distal Biceps Tendon Repair: A Biomechanical Comparison of Intact Tendon and 2 Repair Techniques

Background A variety of techniques have been described for distal biceps tendon reattachment—bone tunnel with transosseous sutures, suture anchors, and interference screw techniques. Hypothesis There will be no significant difference between the mean failure strength, maximum strength, and stiffness of the intact specimen and repair techniques tested: bone tunnel with transosseous sutures and interference screw. Study Design Controlled laboratory study. Methods Nine matched pairs of fresh-frozen human cadaveric elbows were prepared. The intact tendon was pulled from the radial tuberosity; the right and left elbows were randomized to bone tunnels with transosseous sutures or interference screw repair techniques. The repaired specimens were pulled using the same regimen for the intact tendon. Failure strength, maximum strength, and stiffness were measured and compared. Results The mean failure strength, maximum strength, and stiffness of intact tendons were 204.3 ± 76.9 N, 221.7 ± 65.9 N, and 30.1 ± 12.4 N/mm, respectively; for the interference screw specimens, 178.0 ± 54.5 N, 192.1 ± 53.1 N, and 30.4 ± 9.5 N/mm, respectively; and for the bone tunnel specimens, 124.9 ± 22.8 N, 206.6 ± 49.8 N, and 15.9 ± 5.6 N/mm, respectively. There were no significant differences between measures in the intact and interference screw specimens. Mean failure strength and stiffness of the bone tunnel specimens were significantly lower than those of the intact and interference screw specimens; there was no significant difference between the maximum strengths of the treatments. Interference screw failure occurred abruptly with little plastic deformation in nearly all specimens with the tendon and screw pulling out as a unit, often involving fracture of the radial wall. Two of the bone tunnels failed at the bony bridge; the remainder lost bone-tendon contact as the distal tendon was shredded by the suture. Conclusion The results suggest interference screw fixation repair is nearly as strong and stiff as the intact tendon and stronger than the bone tunnel repair technique. Clinical Relevance The interference screw provides better stiffness and failure strength compared with the bone tunnel technique for distal biceps tendon repair. Given the superior mechanical properties, the interference screw technique is recommended as the treatment of choice for biceps tendon rupture repair.