Assessment of Gait Characteristics in Total Knee Arthroplasty Patients Using a Hierarchical Partial Least Squares Method

Quantitative gait analysis is an important tool in objective assessment and management of total knee arthroplasty (TKA) patients. Studies evaluating gait patterns in TKA patients have tended to focus on discrete data such as spatiotemporal information, joint range of motion and peak values of kinematics and kinetics, or consider selected principal components of gait waveforms for analysis. These strategies may not have the capacity to capture small variations in gait patterns associated with each joint across an entire gait cycle, and may ultimately limit the accuracy of gait classification. The aim of this study was to develop an automatic feature extraction method to analyse patterns from high-dimensional autocorrelated gait waveforms. A general linear feature extraction framework was proposed and a hierarchical partial least squares method derived for discriminant analysis of multiple gait waveforms. The effectiveness of this strategy was verified using a dataset of joint angle and ground reaction force waveforms from 43 patients after TKA surgery and 31 healthy control subjects. Compared with principal component analysis and partial least squares methods, the hierarchical partial least squares method achieved generally better classification performance on all possible combinations of waveforms, with the highest classification accuracy 85.14%. The novel hierarchical partial least squares method proposed is capable of capturing virtually all significant differences between TKA patients and the controls, and provides new insights into data visualization. The proposed framework presents a foundation for more rigorous classification of gait, and may ultimately be used to evaluate the effects of interventions such as surgery and rehabilitation.

I. Introduction

Total knee arthroplasty (TKA) is the established treatment for end-stage osteoarthritis, and one of the most commonly performed orthopaedic surgical procedures [1]. Based on self-reported measures of pain and physical function, TKA has been shown to lead to improved knee functional performance and high patient satisfaction [2]; however, gait impairments have been shown to be present in TKA patients, even those with excellent post-operative clinical scores  [3]. These include lower knee range of motion  [4], smaller knee adduction moment [3] , reduced vertical ground reaction forces (GRFs) [5] and decreased hip flexion angles during early stance [6]. Elucidating gait patterns in patients following TKA surgery may assist clinicians in quantifying the influence of different implant designs on gait, as well as evaluating the effectiveness of gait rehabilitation approaches.