Total hip arthroplasty restores lost mobility to patients suffering from osteoarthritis and acute trauma. In recent years, navigated surgery has been used to control prosthetic component placement. Furthermore, there has been increasing research on what constitutes correct placement. This has resulted in the definition of a safe-zone for acetabular cup orientation. However, there is less definition with regard to femoral anteversion and how it should be measured. This study assesses the validity of the femoral anteversion measurement method used in imageless navigation, with particular attention to how the neutral rotation of the femur is defined. CT and gait analysis methodologies are used to validate the reference which defines this neutral rotation, i.e., the ankle epicondyle piriformis (AEP) plane. The findings of this study indicate that the posterior condylar axis is a reliable reference for defining the neutral rotation of the femur. In imageless navigation,when these landmarks are not accessible, the AEP plane provides a useful surrogate to the condylar axis, providing are liable baseline for femoral anteversion measurement.
Bibliographical noteThis is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The moral rights of the named author(s) have been asserted.
FunderThe authors would like to acknowledge the assistance of the Gait Laboratory, based within the School of Engineering at the University of Warwick, and funded through the Science City Research Alliance (SCRA) Translational Medicine Project (a collaborative research program between the Universities of Birmingham and Warwick).
- Total hip arthroplasty
- computer-assisted navigation
- computed tomography
- femoral anteversion
- gait analysis