In vitro evaluation of the tension band suture method for proximal humerus fracture treatment.

Abstract

Proximal humeral fractures are common, and more than half occur in patients over 65 years of age. Operative treatment may be recommended for displaced, complicated fractures; however, surgery may lead to displacement of the greater tuberosity or humeral head. Supplemental tension band sutures have been recommended to prevent such a complication. In this study, we investigate the best combination of suture, washer, and threading angle for proximal humeral fractures from a mechanical view. The mechanical durability of 18 combinations of suture materials (Fiberwire, Ethibond, and Surgilon), threading washers (ring washer, disc washer), and threading angles (15 or 45°) were examined via a cyclic loading test. The most durable combination in the cyclic loading test consisted of threading the Fiber Wire to the washer ring using only one hole (ring washer-1) at 45°. In contrast, the most vulnerable combination was threading Ethibond to the washer disc at 15°. Breakage of all suture materials occurred at the suture-washer interface, and no failure or loosening of the knots was observed. FiberWire gradually eroded until the loss of equilibrium; whereas the rupture of Ethibond and Surgilon occurred suddenly. From a mechanical viewpoint, we demonstrated that applying a supplemental tension band suture using FiberWire with a single-hole ring washer threaded at a wider angle is recommended.