Rotational malalignment of the tibia following reamed intramedullary nail fixation

Objective: To determine the incidence and severity of tibial malrotation following reamed intramedullary nail fixation as measured by computerized tomography and to determine the repeatability of computed tomography measurement in the assessment of rotational malreduction. Design: Prospective cohort. Settings: Level I trauma center. Participants: Twenty-five consecutive patients with 25 tibial shaft fractures. Intervention: All patients were treated with reamed intramedullary nailing. Appropriate radiographs and a postoperative lower extremity computed tomography scan were obtained for each patient who consented to the study. Main Outcome Measure: Rotational alignment of affected tibia as compared to a version of the normal contralateral limb. Malrotation was defined as an internal/external rotation deformity greater than 10degrees. Results: Malrotation, comparing the fractured limb to normal limb, was determined using a similar measurement method previously described in the literature. Two patients declined inclusion, and in one case, the computed tomography was not acceptable for analysis. Malrotation, comparing the fractured limb to the normal limb, was determined using the measurements from axial computed tomography images. Results revealed a mean absolute rotational difference of 6.7degrees (SD +/- 6.3degrees). Rotational malreduction ranged from 15degrees of internal rotation to 22degrees of external rotation. Five of the 22 tibia (22%) were malrotated greater than 10degrees. A larger degree of deformity was seen with certain injury patterns. The intraobserver and interobserver repeatability testing revealed a mean absolute difference between paired malrotation calculations of 3.4degrees and 3.9degrees, respectively, and a repeatability coefficient of 8degrees for both. Conclusion: Computed tomography measurement is a repeatable method of assessing tibial torsion and in this study revealed a significantly higher incidence of rotational malreduction than that previously reported in the literature.