Verification of a Portable Motion Tracking System for Remote Management of Physical Rehabilitation of the Knee

Abstract

Rehabilitation following knee injury or surgery is critical for recovery of function and independence. However, patient non-adherence remains a significant barrier to success. Remote rehabilitation using mobile health (mHealth) technologies have potential for improving adherence to and execution of home exercise. We developed a remote rehabilitation management system combining two wireless inertial measurement units (IMUs) with an interactive mobile application and a web-based clinician portal (interACTION). However, in order to translate interACTION into the clinical setting, it was first necessary to verify the efficacy of measuring knee motion during rehabilitation exercises for physical therapy and determine if visual feedback significantly improves the participant’s ability to perform the exercises correctly. Therefore, the aim of this study was to verify the accuracy of the IMU-based knee angle measurement system during three common physical therapy exercises, quantify the effect of visual feedback on exercise performance, and understand the qualitative experience of the user interface through survey data. A convenience sample of ten healthy control participants were recruited for an IRB-approved protocol. Using the interACTION application in a controlled laboratory environment, participants performed ten repetitions of three knee rehabilitation exercises: heel slides, short arc quadriceps contractions, and sit-to-stand. The heel slide exercise was completed without feedback from the mobile application, then all exercises were performed with visual feedback. Exercises were recorded simultaneously by the IMU motion tracking sensors and a video-based motion tracking system. Validation showed moderate to good agreement between the two systems for all exercises and accuracy was within three degrees. Based on custom usability survey results, interACTION was well received. Overall, this study demonstrated the potential of interACTION to measure range of motion during rehabilitation exercises for physical therapy and visual feedback significantly improved the participant’s ability to perform the exercises correctly.

Validation of a Device to Measure Knee Joint Angles for a Dynamic Movement

“…While the RMSE value observed within our study fell into the range reported by both Tong et al, and Takeda et al (6 • to 9 • ), it was seen to be much higher than that observed by Watanabe et al; 8.11 • in our study compared with a range between 3 • and 4 • reported by Watanabe et al [28][29][30]. Lower RMSE values were seen in studies conducted by both Bakhshi et al (reported range between 0.08 • and 3.06 • ) and Bell et al (reported range between 2 • and 2.9 • ), though in both cases, angles were obtained through the IMU software, not the derivation of angular velocity, as was the case in the previously mentioned studies [27,35]. Previous studies have reported considerably higher interclass correlation coefficients with their respective IMUs (range: 0.94 ≤ ρ < 1) than what was observed within our study (0.34) [27][28][29][30].…”

“…Previous studies have compared the accuracy of various IMU sensors to a motion capture system in order to validate them, though they were primarily concerned with knee flexion angles [27,28,30,35,36]. Studies conducted by Tong et al, Takeda et al and Watanabe et al all derived angles from the gyroscopic data during a gait analysis [28][29][30].…”

“…The studies conducted by Bell et al and Zügner et al also reported the correlation between IMUs and a motion capture system, though they reported intraclass correlation (ICC) [35,36]. While Zügner et al reported a high ICC between their sensors and motion capture system (ICC > 0.8), Bell et al reported values that ranged from moderate to high ICC between their two systems (range: 0.58 ≤ ICC ≤ 0.86) [35,36]. The statistical method used to quantify correlation presented by both Zügner et al and Bell et al, while valid, can be somewhat misleading.…”

“…Of note are the population sizes used in the various studies. [27][28][29][30]35]. The population used by Bakhshi et al had only a single subject, which may not be enough to establish trends [27].…”

A Portable System for Remote Rehabilitation Following a Total Knee Replacement: A Pilot Randomized Controlled Clinical Study

“…The authors have developed and previously validated the accuracy [40] of a remote rehabilitation monitoring platform (interACTION) that uses portable inertial measurement units (IMUs) combined with a mobile application and back-end clinician portal. The present study's objective was to assess the feasibility of utilizing interACTION for remote management of rehabilitation after TKR and to determine a preliminary estimate of the effects of the interACTION system on the value of rehabilitation.…”