Factors Associated With Kirschner Wire Backout After Tension Band Wiring for Olecranon Fractures: A Retrospective Study

BACKGROUND: Tension band wiring (TBW) is widely used for olecranon fractures; however, posterior migration of Kirschner wires (K-wires), termed "backout," is a common complication. At our institution, during intramedullary fixation, the proximal ends of K-wires are bent by 180° and embedded into the olecranon fragment. This study aimed primarily to identify clinical and radiographic factors associated with K-wire backout after TBW for olecranon fractures, and secondarily to explore clinically relevant thresholds of insertion depth and backout distance in relation to postoperative symptoms and reoperation. METHODS: We retrospectively reviewed data from 34 patients with olecranon fractures who underwent TBW and intramedullary K-wire fixation at our institute between 2014 and 2023. The backout distance was measured using postoperative radiographs. Patients were divided into backout (≥ 5 mm) and non-backout (< 5 mm) groups, and their clinical and radiographic parameters were compared. RESULTS: The mean follow-up period was 12 months. Irritation symptoms occurred in 11 (33%) of the cases, and implant removal was required in 18 (53%). The insertion depth was significantly shallower in the backout group than in the non-backout group. The data suggested that an insertion depth of approximately 4-5 mm may be a practical target to reduce the likelihood of clinically relevant backout. Although thinner K-wires (1.6 mm) were used more frequently in the backout group, diameter was not independently associated with backout. Backout exceeding approximately 7-8 mm was frequently observed in patients with irritation symptoms and those who underwent reoperation. CONCLUSION: In this retrospective cohort, a shallower embedding depth of the bent K-wire tip was associated with a higher likelihood of postoperative backout. Ensuring sufficient insertion depth and the use of thicker wires, when feasible, may help reduce complications following TBW.