Functional knee phenotypes of OA patients undergoing total knee arthroplasty are significantly more varus or valgus than in a non‐OA control group

Abstract

Purpose The aim of this study was to analyse the coronal alignment of a large population of patients undergoing total knee arthroplasty using a modern classification of the knee phenotypes found in a population of non-osteoarthritic individuals. Methods Five hundred and four navigated total knee arthroplasties were included in the OA group. The following angles were measured with a computer image-free navigation system: mechanical femorotibial angle measured on the medial side without stress and with maximum manual stress to reduce deformation, and medial distal femoral mechanical angle. The native medial distal femoral and medial proximal tibial angles (coronal orientation of the femoral or tibial joint line after correction of wear) were calculated. The data were analysed as categorical data. These data were then compared with those published in a non-arthritic population, considered as a control non-OA group. The main criterion was the percentage of subjects with normal overall coronal alignment, defined by the association of a normal native medial distal femoral angle and a normal native medial proximal tibial angle. The secondary criteria were the percentages of subjects with normal medial femorotibial mechanical angle, normal native medial distal femoral angle and normal native medial proximal tibial angle. The influence of gender on primary and secondary criteria in the study group was analysed. The most frequent phenotypes in the study group were identified. Results N…