Large Individual Bilateral Differences in Tibial Torsion Impact Accurate Contralateral Templating and the Evaluation of Rotational Malalignment.

OBJECTIVE: To determine individual bilateral differences (IBDs) in tibial torsion in a diverse population. METHODS: Computed tomography scans of uninjured bilateral tibiae were used to determine tibial torsion and IBDs in torsion using 4 measurement methods. Age, sex, and self-identified race/ethnicity were also recorded for each subject. Mean tibial torsion and IBDs in torsion were compared in the overall cohort and when stratified by sex and race/ethnicity. Simple and multiple linear regression models were used to correlate demographic variables with tibial torsion and IBDs in torsion. RESULTS: One hundred ninety-five patients were evaluated. The mean tibial torsion was 27.5 ± 8.3 degrees (range -3 to 47.5 degrees). The mean IBD in torsion was 5.3 ± 4.0 degrees (range 0-23.5 degrees, P < 0.001). 12.3% of patients had IBDs in torsion of ≥10 degrees. In the regression analysis, patients who identified as White had greater average torsion by 4.4 degrees compared with Hispanic/Latinx patients (P = 0.001), whereas age and sex were not significantly associated with absolute torsion. Demographics were not associated with significant differences in IBDs in torsion. CONCLUSIONS: Tibial torsion varies considerably and individual side-to-side differences are common. Race/ethnicity was associated with differences in the magnitude of tibial torsion, but no factors were associated with bilateral differences in torsion. The results of this study may be clinically significant in the context of using the uninjured contralateral limb to help establish rotational alignment during medullary nail stabilization of diaphyseal tibia fractures. In addition, these findings should be considered in the evaluation of tibia rotational malalignment. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.