Ramon Gheno MD, Presenter: Nothing to Disclose

Eric Nectoux MD, Abstract Co-Author: Nothing to Disclose

Bernard Herbaux, Abstract Co-Author: Nothing to Disclose

Matteo Baldisserotto MD, Abstract Co-Author: Nothing to Disclose

Anne Cotten MD, Abstract Co-Author: Nothing to Disclose

Nathalie Boutry, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to determine the utility of a bi-planar X-rays device, called EOS, in the evaluation of the misalignment of the lower limbs in adolescents.

Two radiologists analyzed retrospectively two and three-dimensional measurements of 47 lower limbs of 27 randomized adolescents. The evaluated parameters were the femoral and tibial length, femoral and tibial mechanical angle, frontal and lateral knee angulation, and the cervicodiaphysary angle. The analysis was performed using a semi-automated software for the three-dimensional measurements and a conventional imaging processor for the two-dimensional measurements. An interobserver analysis was also performed. Wilcoxon and student's t tests, as well as Pearson and Spearman correlations were used for statistical analysis.

The comparison between two and three dimensional measurements showed significant differences in tibial length (p: 0,003), femoral mechanical angle (p < 0,001) and cervicodiaphysary angle (p: 0,001). Differences regarding the other parameters were unremarkable: femoral length (p: 0,267), tibial mechanical angle (p: 0,342), frontal knee angulation (p: 0,725) and lateral knee angulation (p: 0,101). The interobserver analysis presented good correlations for the femoral length (r: 0,991), tibial length (r: 0,996), frontal knee angulation (r:0,829) and lateral knee angulation (r:0,950). Moderate agreement was observed in the femoral mechanical angle (r:0,644), tibial mechanical angle (r:0,603) and cervicodiaphisary angle (r: 0,756).

Besides the overall good agreement within the observers, some differences in the comparison between two and three dimensional measurements were found, as expected. These differences are believed to be originated not just from the spatial orientation of the lines (using two or three coordinates) but also from the degrees of femoral and tibial rotation, as well as flexion or extension of the knee. Future studies are clearly needed to define normal values for 3D measurements.

There are no studies in the literature analysing the usefulness and indications of the three dimensional measurements in adolescents.

Gheno, R, Nectoux, E, Herbaux, B, Baldisserotto, M, Cotten, A, Boutry, N, Three-dimensional Evaluation of the Lower Limbs in Adolescents Using the EOS System.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11012952.html