Three-dimensional analysis of functional femoral antetorsion and the position of the greater trochanter in high-grade patellofemoral dysplastic knees

Background: The relationship between functional femoral antetorsion, the greater trochan-ter (GT) position and anatomical antetorsion has been demonstrated in patients with a pri-mary hip pathology. However, the functional antetorsion and GT position have not been analyzed in patellofemoral dysplastic knees. The aim of this study was to develop a three-dimensional (3D) measurement to quantify the functional femoral antetorsion and position of the GT and to analyze these measurements in a cohort of high-grade patellofe-moral dysplastic knees.Method: A 3D measurement was developed to analyze functional antetorsion and the axial position of the GT and assessed in 100 cadaveric femora. For validity and repeatability test-ing, inter-and intra-observer reliability were determined using intraclass correlation coef-ficients (ICCs). These measurements were then evaluated in a cohort of 19 high-grade patellofemoral dysplastic knees (Dejour type C, D). The relationship between anatomical antetorsion, functional antetorsion and GT position were reported.Results: Inter-and intra-reader reliability for 3D functional antetorsion and axial position of the GT demonstrated a minimum ICC of 0.96 (P < 0.001). Anatomical and functional antetorsion demonstrated a highly linear relationship (R2 = 0.878; P < 0.001) in high-grade patellofemoral dysplastic knees. The mean difference between anatomical and func-tional antetorsion decreased with increasing anatomical antetorsion (R2 = 0.25; P = 0.031, indicating a more anterior position of the GT relative to the femoral neck axis.Conclusion: In high-grade patellofemoral dysplastic knees, the GT is located more anteri-orly, relative to the femoral neck axis, with increasing anatomical antetorsion and correc-tion osteotomy may result in an excessively anterior position of the GT.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).