Three Dimensional Morphologic Analysis of the Lateral Surface of the Canine Femur

Objectives Analyze the lateral plating surface of the femur to obtain bend and twist angles in dogs with non-chondrodystrophic phenotype. Study Design Retrospective computed tomography (CT) morphologic analysis. Sample Population Historical cohort, hindlimb CT scans (n = 30). Materials and Methods The CT images of 30 normal femurs were uploaded to surgical planning software and 13 points of interest and their respective bend/twist angles were identified on the lateral surfaces. Mean, standard deviation, coefficient of variation (CV), and range were calculated for each bend/twist angle. Hierarchal clustering and fast Fourier Analyses were used to segment the cohort. Distribution of age, breed, sex, and weight was evaluated between clusters with an exact Wilcoxon–Mann–Whitney test. Results The CV of bending ranged from 17% to 46% and for twisting ranged from 21% to 58%. The greater trochanter was the most pronounced bend on the lateral surface of the femur (mean ± SD 8.11 ± 1.35°, CV 17%), and the supracondylar region of the distal femur was the most marked twist (mean ± SD 48.98 ± 10.06°, CV 21%). Although there were no differences between dogs in proximal femur anatomy, 2 clusters of 9 and 21 dogs each were identified due to differences in bend/twist angles in the distal femur. There was no difference between clusters for age (P = .85), breed (P = .62), and sex (P = .15); however, weight differed (P = .03) but was not predictive. Conclusion Although distal femoral lateral surfaces varied sufficiently to result in 2 population clusters, further analysis is needed to determine if the differences prevent using the mean bending and twisting parameters as a template for clinical applications.