Are pre- and postoperative true translational and angular displacement predictive of nonunion after intramedullary nail fixation of tibial shaft fractures?

PURPOSE: To determine if there is an association between pre-/postoperative translational and angular displacement with nonunion after intramedullary nail (IMN) fixation of tibial shaft fractures. METHODS: Retrospective review of 120 patients with tibial shaft fractures undergoing IMN at an urban level-one trauma center was performed. Demographics, injury characteristics, and pre-/postoperative translational and angular fracture displacement in the coronal and sagittal planes were recorded. True fracture translational and angular displacement (TTD and TAD) were calculated by combining sagittal and coronal displacement utilizing the Pythagorean theorem. RESULTS: 10.8% of patients (n = 13) developed nonunion with remaining patients serving as the control. Groups were similar across age, sex, and BMI. Univariate analysis revealed no difference in pre-/postoperative TAD between nonunion and union groups and an increased preoperative TTD (median difference (MD): 6.2 mm, CI: 1.4-10.8 mm) and postoperative TTD (MD: 1.8 mm, CI: 0-3.7 mm) in the nonunion group. On multivariate analysis, however, only tobacco use and type 2 or 3 open fractures were associated with nonunion (OR: 5.1, CI: 1.2-22.8 and OR: 4.9, CI: 1.2-19.2, respectively). CONCLUSION: True translational and angular displacement of tibial shaft fractures before and after IMN fixation were not independently associated with nonunion. Tobacco use and type 2 or 3 open fracture are independent factors for nonunion.