A new intramedullary fixation method for distal biceps tendon ruptures: a biomechanical study

Background: Various techniques have been described for distal biceps tendon reinsertion. Although high success rates have been reported, all current techniques have specific shortcomings, with complications such as heterotopic ossification, nerve damage, and gap formation. The purpose of the present study was to hiomechanically evaluate a new intramedullary fixation device that might reduce the risk of posterior interosseous nerve lesions. We therefore compared the fixation strength of this new intramedullary button with an extramedullary placed classic extracortical button. Methods: A standard bicortical button was compared to the new intramedullary fixation device using fresh-frozen cadaveric specimens. The fixation strengths were tested both cyclically and statically. Load to failure and method of failure were also recorded. Results: There were no failures during the cyclic load testing. The mean tendon-bone displacement was 0.87 +/- 0.13 mm for the bicortical group and 0.83 +/- 0.13 mm for the new button. During static loading, the mean load to failure for the bicortical group was 296 +/- 97 N, whereas the new button group showed a higher mean load to failure of 356 +/- 37 N. Breakout through the anterior cortex was recorded in 2 of 6 bicortically placed buttons and 1 of 6 in the new device. Conclusions: The new intramedullary fixation device yields comparable loads to failure compared with currently used techniques in a biomechanical setup. These findings together with the theoretical advantages suggest that this technique may be a valuable solution for the repair of distal biceps tendon rupture. (C) 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.