Towards an Inertial Sensor-Based Wearable Feedback System for Patients after Total Hip Arthroplasty: Validity and Applicability for Gait Classification with Gait Kinematics-Based Features.

Teufl Teufl,Jöllenbeck Jöllenbeck,Fröhlich Fröhlich,Lorenz Lorenz,Bleser Bleser,Miezal Miezal,Taetz Taetz,Pietschmann Pietschmann

doi:10.3390/s19225006

Teufl Teufl, Jöllenbeck Jöllenbeck + Show 6 more

Open Access

https://doi.org/10.3390/s19225006

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Abstract

Patients after total hip arthroplasty (THA) suffer from lingering musculoskeletal restrictions. Three-dimensional (3D) gait analysis in combination with machine-learning approaches is used to detect these impairments. In this work, features from the 3D gait kinematics, spatio temporal parameters (Set 1) and joint angles (Set 2), of an inertial sensor (IMU) system are proposed as an input for a support vector machine (SVM) model, to differentiate impaired and non-impaired gait. The features were divided into two subsets. The IMU-based features were validated against an optical motion capture (OMC) system by means of 20 patients after THA and a healthy control group of 24 subjects. Then the SVM model was trained on both subsets. The validation of the IMU system-based kinematic features revealed root mean squared errors in the joint kinematics from 0.24° to 1.25°. The validity of the spatio-temporal gait parameters (STP) revealed a similarly high accuracy. The SVM models based on IMU data showed an accuracy of 87.2% (Set 1) and 97.0% (Set 2). The current work presents valid IMU-based features, employed in an SVM model for the classification of the gait of patients after THA and a healthy control. The study reveals that the features of Set 2 are more significant concerning the classification problem. The present IMU system proves its potential to provide accurate features for the incorporation in a mobile gait-feedback system for patients after THA.

Highlights

Hip osteoarthritis describes a degenerative process of the cartilage at the hip joint
The present examination evaluated the applicability of features taken from the inertial measurement unit (IMU)-based 3D gait kinematics of the lower body for the discrimination of the gait of patients after total hip arthroplasty (THA) and a healthy control
The features were divided into two groups of features, spatio-temporal gait parameters (STP) and joint kinematics, due to the different kind of measurement approach to these variables

Summary

Introduction

Hip osteoarthritis describes a degenerative process of the cartilage at the hip joint. Pain and immobility are the common consequences leading to changed gait patterns in the affected subjects. Total hip arthroplasty (THA) is considered the most promising option once conservative therapies are exhausted [1]. Gait abnormalities, such as asymmetries in the kinematics between implanted and non-implanted hip joints, persist even after successful THA and the consecutive rehabilitation process [2]. The literature reveals persisting changes of the joint angle kinematics of the implanted. According to Queen et al [6], these asymmetries persist up to one year after the THA and they recommend a continuative physical therapy to eliminate these deviations

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Conclusion