The availability of radiological measurement of tibial torsion: three-dimensional computed tomography reconstruction.

OBJECTIVE: To assess the intra-rater and inter-rater reliability for measuring tibial torsion measurements by a radiographic method using three-dimensional computed tomography reconstruction (3D-CT) and to compare the physical measures to those of 3D-CT.

METHOD: The study included 33 children who presented with intoeing gait. Tibial torsion was measured by 3D-CT. Distal reference point was the bimalleolar axis. Proximal reference points were the transtibial axis and posterior condylar axis. Physical measurements included thigh-foot angle (TFA) and bimalleolar angle (BMA). 3D-CT measurement and physical measurement were performed twice at both lower extremities by each rater. The intra-rater and inter-rater reliability were calculated by intraclass correlation coefficiency (ICC). The relationship between radiological and physical examination was calculated by Spearman correlation coefficient.

RESULTS: The 3D-CT measures for tibial torsion were reliable within individual raters and between different raters. However, physical measures for tibial torsion were reliable within an individual rater but not reliable between raters. The 3D-CT measures by any proximal reference axis were more reliable within a rater and between raters than physical measurements. There was no significant impact introduced by the selection of the proximal reference axis. The correlation coefficiency between 3D-CT and physical measurement methods was low.

CONCLUSION: Because the 3D-CT measurements for tibial torsion are more reliable than physical measurements, we recommend that accurate diagnosis of internal tibial torsion should be detected by using 3D-CT measurements. Also, considering the disadvantages of radiological measurements, physical measurement may be used for short term follow-up by same raters, as intra-rater reliability is relatively good.