Does Computer-Assisted Femur First THR Improve Musculoskeletal Loading Conditions?

Tim A Weber,Tobias Renkawitz,Joachim Grifka,Sebastian Dendorfer,Gijsbertus J Verkerke

doi:10.1155/2015/625317

Abstract

We have developed a novel, computer-assisted operation method for minimal-invasive total hip replacement (THR) following the concept of “femur first/combined anteversion,” which incorporates various aspects of performing a functional optimization of the prosthetic stem and cup position (CAS FF). The purpose of this study is to assess whether the hip joint reaction forces and patient's gait parameters are being improved by CAS FF in relation to conventional THR (CON). We enrolled 60 patients (28 CAS FF/32 CON) and invited them for gait analysis at three time points (preoperatively, postop six months, and postop 12 months). Data retrieved from gait analysis was processed using patient-specific musculoskeletal models. The target parameters were hip reaction force magnitude (hrf), symmetries, and orientation with respect to the cup. Hrf in the CAS FF group were closer to a young healthy normal. Phase-shift symmetry showed an increase in the CAS FF group. Hrf orientation in the CAS FF group was closer to optimum, though no edge or rim-loading occurred in the CON group as well. The CAS FF group showed an improved hrf orientation in an early stage and a trend to an improved long-term outcome.

Highlights

Total hip replacement (THR) is one of the most successful operations of the 20th century [1]
Several authors have proposed starting with the preparation of the femur and transferring the orientation of the stem relative to the cup intraoperatively (“femur first,” “combined anteversion”) in order to minimize the risk of impingement and dislocation [7,8,9,10]
The purpose of the current study is to assess whether the artificial joint’s hip reaction forces and patient’s gait parameters can be improved by Computer-Assisted Minimally Invasive Femur First THR (CAS FF) THR by means of a combined workflow of experimental and computational methods relative to conventional THR

Summary

Introduction

Total hip replacement (THR) is one of the most successful operations of the 20th century [1]. Biomathematical calculations have shown that prosthetic instability can be reduced by regarding stem and cup as coupled partners in a biomechanical system [6]. In this context, several authors have proposed starting with the preparation of the femur and transferring the orientation of the stem relative to the cup intraoperatively (“femur first,” “combined anteversion”) in order to minimize the risk of impingement and dislocation [7,8,9,10]. One method to analyze hrf is to employ instrumented implants (II) [17, 18] This method is regarded as the gold standard, since it is the only way to measure such forces in vivo; it bears the disadvantage of being highly invasive. Validation of such models has been achieved by comparing computed

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Discussion

Conclusion