Lower extremity muscle strength training is a focus of rehabilitation following total hip arthroplasty (THA). Strength of the hip abductor muscle group is a predictor of overall function following THA. The purpose of this study was to investigate the effects of hip abductor strengthening following rehabilitation on joint contact forces (JCFs) in the lower extremity and low back during a high demand step down task. Five THA patients performed lower extremity maximum isometric strength tests and a stair descent task. Patient-specific musculoskeletal models were created in OpenSim and maximum isometric strength parameters were scaled to reproduce measured pre-operative joint torques. A pre-operative forward dynamic simulation of each patient performing the stair descent was constructed using their corresponding patient-specific model to predict JCFs at the ankle, knee, hip, and low back. The hip abductor muscles were strengthened with clinically supported increases (0–30%) above pre-operative values in a probabilistic framework to predict the effects on peak JCFs (99% confidence bounds). Simulated hip abductor strengthening resulted in lower peak JCFs relative to pre-operative for all five patients at the hip (18.9–23.8 ± 16.5%) and knee (20.5–23.8 ± 11.2%). Four of the five patients had reductions at the ankle (7.1–8.5 ± 11.3%) and low back (3.5–7.0 ± 5.3%) with one patient demonstrating no change. The reduction in JCF at the hip joint and at joints other than the hip with hip abductor strengthening demonstrates the dynamic and mechanical interdependencies of the knee, hip and spine that can be targeted in early THA rehabilitation to improve overall patient function.
|Number of pages||10|
|Journal||Journal of Biomechanics|
|State||Published - Aug 27 2019|
Bibliographical noteFunding Information:
This study was supported by the National Institute on Aging of the National Institutes of Health under Award Number T32AG000279 , the NIH/NCATS Colorado CTSA Grant Number UL1 TR001082 , and the Donald W. Gustafson Fellowship in Orthopaedic Biomechanics.
This study was supported by the National Institute on Aging of the National Institutes of Health under Award Number T32AG000279, the NIH/NCATS Colorado CTSA Grant Number UL1 TR001082, and the Donald W. Gustafson Fellowship in Orthopaedic Biomechanics.
© 2019 Elsevier Ltd
- Hip arthroplasty
- Joint contact forces
- Muscle strength
- Musculoskeletal modeling
- Regional interdependence
ASJC Scopus subject areas
- Biomedical Engineering
- Orthopedics and Sports Medicine