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

Abstract

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 6 8.3 degrees (range 23 to 47.5 degrees). The mean IBD in torsion was 5.3 6 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 individualside-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.

The Intermalleolar Method for Intraoperative Rotational Assessment of the Tibia – A Prospective Clinical Validation Study

“…First, it provides an absolute value that reflects the actual rotation of the tibia rather than a proxy value or the requirement of the surgeon to compare relative radiographic overlap of anatomic structures. Even though large variation of anatomic tibial rotation exists within the population and even within an individual, 17,18 the absolute value is useful, particularly when the contralateral limb cannot be used as a reliable comparison. For example, in the setting of amputation, total knee or ankle arthroplasty, or deformity, the injured limb's rotation can be set to that of the population norm of approximately 30 degrees.…”

“…For example, in the setting of amputation, total knee or ankle arthroplasty, or deformity, the injured limb's rotation can be set to that of the population norm of approximately 30 degrees. [17][18][19][20] It is important to interpret the results of this study with consideration of the strengths and limitations. The intraoperative measurements throughout the course of the study were performed by 3 orthopaedic traumatologists, improving the generalizability of this study with multiple observers.…”

“…For example, in the setting of amputation, total knee or ankle arthroplasty, or deformity, the injured limb's rotation can be set to that of the population norm of approximately 30 degrees. 17–20…”

“…The most commonly used techniques were fluoroscopic fracture reduction reads, cortical thickness, and clinical examination in addition to the intermalleolar measurement values when assessing tibial rotation, but attempts were not made to use the intraoperative fluoroscopic method to perfectly match the limbs knowing that potentially large bilateral differences exist. Gallo et al 18 and Volkmar et al 21 studied bilateral lower extremity CT scans in patients without femur or tibia trauma and found 12.3%–18% of patients had a >10-degree bilateral rotational difference. Therefore, it was not felt to be necessary to report how often the injured side was within 10 degrees of the uninjured side.…”

Trauma

“…The study reported here from Los Angeles (California, USA) included 195 scans with calculated rotations. 10 The mean external rotation was 27°, with a mean difference (IBD) of 5° between legs. A > 10° difference was present in 12.3% of reported cases, and was more likely if the reported baseline amount of torsion was higher.…”