Movement Quality Parameters During Gait Assessed by a Single Accelerometer in Subjects with Osteoarthritis and Following Total Joint Arthroplasty

Background: This study aimed to evaluate which of movement quality parameters measured with a single trunk worn Inertial Measurement Unit (IMU) can distinguish the gait pattern of people with hip or knee osteoarthritis (OA) compared to asymptomatic controls. Secondly, we evaluated the sensitivity of these parameters to capture gait changes at 6 weeks, 3, 6, and 12 months following total knee arthroplasty (TKA). Thirdly, we investigated whether observed changes in movement quality from 6 weeks and 12 months following total knee arthroplasty were related to changes in patient-reported outcome measures.Methods: Twenty people with hip OA, 18 people with knee OA, and 20 asymptomatic controls participated in this study. Seventeen people with knee OA were treated with a TKA and additionally followed for one year postoperatively. The participants were equipped with a single trunk-worn IMU and were instructed to walk back and forth along a 10m walkway at a self-selected speed. The movement quality parameters (quantified by symmetry—step/stride regularity; complexity—Sample entropy; smoothness—Log Dimensionless Jerk; and dynamic stability—maximum Lyapunov Exponent) were calculated from the raw 3D acceleration signal. Comparisons were made between groups and between timepoints in the TKA patients. Finally, changes in movement quality were correlated with patient-reported outcomes in the TKA group.Results: We found significant group differences in movement symmetry and stability pre-operatively. Post-TKA, all parameters, except movement smoothness, reflected an initial decrease in movement quality at 6 weeks post-TKA, but all except movement complexity, normalised after 6 months. Moreover, improved movement quality (6 weeks-12 months post-TKA) related to improvements in patient-reported outcome measures.Conclusions: A single lower back IMU can characterise movement quality before and after a total joint arthroplasty. Most symmetry measures recovered but a more unstable, less complex gait pattern was observed at follow-up. The correlation between these parameters and patient-reported outcome measures shows the potential to monitor movement quality in a clinical setting to inform objective data driven personalised rehabilitation of quantified gait symmetry, stability, complexity, and smoothness.