Patient-specific musculoskeletal modeling of the hip joint for preoperative planning of total hip arthroplasty: A validation study based on in vivo measurements

<div><p>Validation of musculoskeletal models for application in preoperative planning is still a challenging task. Ideally, the simulation results of a patient-specific musculoskeletal model are compared to corresponding in vivo measurements. Currently, the only possibility to measure in vivo joint forces is to implant an instrumented prosthesis in patients undergoing a total joint replacement. In this study, a musculoskeletal model of the AnyBody Modeling System was adapted patient-specifically and validated against the in vivo hip joint force measurements of ten subjects performing one-leg stance and level walking. The impact of four model parameters was evaluated; hip joint width, muscle strength, muscle recruitment, and type of muscle model. The smallest difference between simulated and in vivo hip joint force was achieved by using the hip joint width measured in computed tomography images, a muscle strength of 90 N/cm², a third order polynomial muscle recruitment, and a simple muscle model. This parameter combination reached mean deviations between simulation and in vivo measurement during the peak force phase of 12% ± 14% in magnitude and 11° ± 5° in orientation for one-leg stance and 8% ± 6% in magnitude and 10° ± 5° in orientation for level walking.</p></div

Results for level walking using CT-HJW, 90 N/cm² muscle strength, PN recruitment, and simple muscle model (n = 10).

<p>Results for level walking using CT-HJW, 90 N/cm² muscle strength, PN recruitment, and simple muscle model (n = 10).</p

Deviations between simulated and in vivo HJF for one-leg stance and level walking for each combination of the four investigated parameters.

<p>Only successful simulations were included. The parameter combinations with the smallest MAPE^PFP, the smallest sum of RMSE_ML, RMSE_PA and RMSE_IS, as well as the smallest RMSE_R are marked in grey.</p

Anthropometric data of the ten patients with the instrumented Hip III implant of the OrthoLoad database.

<p>Anthropometric data of the ten patients with the instrumented Hip III implant of the OrthoLoad database.</p

Individual results for one-leg stance and level walking averaged over the full motion cycle for CT-HJW, 90 N/cm² muscle strength, PN recruitment, and simple muscle model.

<p>Mean and standard deviation (SD) are presented in %BW for the AnyBody (AB) simulations, the OrthoLoad (OL) in vivo measurements and the MAE of the AnyBody simulations in each direction of the HJF. MAE above 50%BW are marked in grey.</p