Smoking and lateral hinge fracture are associated with delayed union at 6 months in open wedge distal tibial tuberosity osteotomy.

Purpose: This study aimed to identify risk factors for delayed union 6 months after open wedge distal tibial tuberosity osteotomy (owDTO) using computed tomography (CT) and to evaluate the association between distal flange and posterior cortex union. Methods: This retrospective study was conducted on all patients who underwent owDTO. The exclusion criteria were failure to undergo a 6-month postoperative follow-up, absence of CT evaluation, simultaneous anterior cruciate ligament reconstruction, double-level osteotomy and cases requiring multiple surgical debridements for deep infection. Bone union rates at the flange and posterior cortex were evaluated using CT images obtained 6 months postoperatively. Bone union was determined using zone classification from a previous report. Various factors influencing bone union were examined. Statistical significance was set at Results: Of the 122 knees reviewed, a total of 79 knees from 77 patients (43 males and 34 females; age, 55 ± 10 years) were analysed after the exclusion of 43 knees. Twenty-two patients were current smokers. The body mass index was 25.1 ± 3.8 kg/m Conclusions: Smoking and LHF were associated with delayed union at 6 months in owDTO. Distal flange union was significantly associated with posterior cortex union. These findings may assist surgeons in identifying patients at risk for delayed union after owDTO and may contribute to improved postoperative management. Level of Evidence: Level IV, retrospective study.