The effect of surgical change to hip geometry on hip biomechanics after primary total hip arthroplasty
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(Published version)
Date
2023
Authors
Bahl, J.S.
Arnold, J.B.
Saxby, D.J.
Taylor, M.
Solomon, L.B.
Thewlis, D.
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Journal article
Citation
Journal of Orthopaedic Research, 2023; 41(6):1240-1247
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Jasvir S. Bahl, John B. Arnold, David J. Saxby, Mark Taylor, Lucian B. Solomon, Dominic Thewlis
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Abstract
The aim of this study was to determine the effect of surgical change to the acetabular offset and femoral offset on the abductor muscle and hip contact forces after primary THA using computational methods. Thirty-five patients undergoing primary THA were recruited. Patients underwent a computed tomography scan of their pelvis and hip, and underwent gait analysis pre- and 6-months post-operatively. Surgically induced changes in acetabular and femoral offset were used to inform a musculoskeletal model to estimated abductor muscle and hip joint contact forces. Two experiments were performed: (1) influence of changes in hip geometry on hip biomechanics with preoperative kinematics; and (2) influence of changes in hip geometry on hip biomechanics with postoperative kinematics. Superior and medial placement of the hip centre of rotation during THA was most influential in reducing hip contact forces, predicting 63% of the variance (p<0.001). When comparing the preoperative geometry and kinematics model, with postoperative geometry and kinematics, hip contact forces increased after surgery (0.68 BW, p=0.001). Increasing the abductor lever arm reduced abductor muscle force by 28% (p<0.001) and resultant hip contact force by 17% (0.6 BW, p=0.003), with both preoperative and postoperative kinematics. Failure to increase abductor lever arm increased resultant hip contact force 11% (0.33 BW, p<0.001). In conclusion, increasing the abductor lever arm provides a substantial biomechanical benefit to reduce hip abductor and resultant hip joint contact forces. The magnitude of this effect is equivalent to the average increase in hip contact force seen with improved gait from pre-to post-surgery. This article is protected by copyright. All rights reserved.
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Published June 2023
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© 2022 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.