Three dimensional morphologic analysis of the lateral surface of the canine femur.

ObjectivesAnalyze the lateral plating surface of the femur to obtain bend and twist angles in dogs with non-chondrodystrophic phenotype. Study DesignRetrospective computed tomography (CT) morphologic analysis. Sample PopulationHistorical cohort, hindlimb CT scans (n=30). Materials and MethodsThe 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. ResultsThe 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 (meanSD 8.11 +/- 1.35 degrees, CV 17%), and the supracondylar region of the distal femur was the most marked twist (mean +/- SD 48.98 +/- 10.06 degrees, 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. ConclusionAlthough 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.