Validation of an Inertial Sensor System for Physical Therapists to Quantify Movement Coordination During Functional Tasks

Associations Between Music and Dance Relationships, Rhythmic Proficiency, and Spatiotemporal Movement Modulation Ability in Adults with and without Mild Cognitive Impairment

Background

Personalized dance-based movement therapies may improve cognitive and motor function in individuals with mild cognitive impairment (MCI), a precursor to Alzheimer's disease. While age- and MCI-related deficits reduce individuals' abilities to perform dance-like rhythmic movement sequences (RMS)-spatial and temporal modifications to movement-it remains unclear how individuals' relationships to dance and music affect their ability to perform RMS.

Objective

Characterize associations between RMS performance and music or dance relationships, as well as the ability to perceive rhythm and meter (rhythmic proficiency) in adults with and without MCI.

Methods

We used wearable inertial sensors to evaluate the ability of 12 young adults (YA; age = 23.9±4.2 years; 9F), 26 older adults without MCI (OA; age = 68.1±8.5 years; 16F), and 18 adults with MCI (MCI; age = 70.8±6.2 years; 10F) to accurately perform spatial, temporal, and spatiotemporal RMS. To quantify self-reported music and dance relationships and rhythmic proficiency, we developed Music (MRQ) and Dance Relationship Questionnaires (DRQ), and a rhythm assessment (RA), respectively. We correlated MRQ, DRQ, and RA scores against RMS performance for each group separately.

Results

The OA and YA groups exhibited better MRQ and RA scores than the MCI group (p < 0.006). Better MRQ and RA scores were associated with better temporal RMS performance for only the YA and OA groups (r2 = 0.18-0.41; p < 0.045). DRQ scores were not associated with RMS performance in any group.

Conclusions

Cognitive deficits in adults with MCI likely limit the extent to which music relationships or rhythmic proficiency improve the ability to perform temporal aspects of movements performed during dance-based therapies.

Exercise quantification from single camera view markerless 3D pose estimation

Sports physiotherapists and coaches are tasked with evaluating the movement quality of athletes across the spectrum of ability and experience. However, the accuracy of visual observation is low and existing technology outside of expensive lab-based solutions has limited adoption, leading to an unmet need for an efficient and accurate means to measure static and dynamic joint angles during movement, converted to movement metrics useable by practitioners. This paper proposes a set of pose landmarks for computing frequently used joint angles as metrics of interest to sports physiotherapists and coaches in assessing common strength-building human exercise movements. It then proposes a set of rules for computing these metrics for a range of common exercises (single and double drop jumps and counter-movement jumps, deadlifts and various squats) from anatomical key-points detected using video, and evaluates the accuracy of these using a published 3D human pose model trained with ground truth data derived from VICON motion capture of common rehabilitation exercises. Results show a set of mathematically defined metrics which are derived from the chosen pose landmarks, and which are sufficient to compute the metrics for each of the exercises under consideration. Comparison to ground truth data showed that root mean square angle errors were within 10° for all exercises for the following metrics: shin angle, knee varus/valgus and left/right flexion, hip flexion and pelvic tilt, trunk angle, spinal flexion lower/upper/mid and rib flare. Larger errors (though still all within 15°) were observed for shoulder flexion and ASIS asymmetry in some exercises, notably front squats and drop-jumps. In conclusion, the contribution of this paper is that a set of sufficient key-points and associated metrics for exercise assessment from 3D human pose have been uniquely defined. Further, we found generally very good accuracy of the Strided Transformer 3D pose model in predicting these metrics for the chosen set of exercises from a single mobile device camera, when trained on a suitable set of functional exercises recorded using a VICON motion capture system. Future assessment of generalization is needed.

Systematic analysis of different low-pass filter cut-off frequencies on lumbar spine kinematics data and the impact on the agreement between accelerometers and an optoelectronic system

A necessary step in the validation of accelerometers for the measurement of spine angles is to determine the levels of agreement with current gold standard methods. However, agreement may be a function of filtering parameters. We aimed to (1) systematically determine the effect of different filter frequency cut-offs on the peak range of motion (ROM) during forward bending as measured by accelerometers and an optoelectronic (OE) system, (2) explore the influence of filtering on agreement between systems, and (3) determine the difference in peak ROM measurement between these systems. Accelerometers and OE sensors were attached at L2, L4, and S1 of 20 asymptomatic female participants for a guided flexion trial. Signals were then iteratively low-pass filtered with cut-off frequencies ranging from 14 Hz to 1 Hz and peak range of motion outcome measures were compared between systems. Peak ROM was minimally affected by filter cut-off frequency for both accelerometer and OE system. The difference in peak ROM between difference cut-off frequencies were maximum 0.66°, median 0.18° and minimum 0.06° for accelerometer derived values and maximum 0.23°, median 0.08° and minimum 0.03° for the OE system. The maximum difference across the filtering frequencies was 0.62° and the largest difference between the two systems (with outliers removed) was 0.82°. Cut-off frequencies ranging from 14 to 1 Hz had little effect of peak lumbar spine ROM during low velocity (6°/s) forward bending, regardless of motion capture method. Filtering cut-off frequency had little effect on the differences between the accelerometer and OE system and similar measurements can be achieved using accelerometers compared to OE systems.

Physiotherapists could detect changes of 12 degrees or more in single-plane movement when observing forward bending, squat or hand-over-head: A cross-sectional experiment

BACKGROUND

The visual accuracy of physiotherapists to detect changes in dynamic joint angles is currently unknown.

OBJECTIVE

To investigate (i) the smallest detectable change in movement that physiotherapists could visually observe, and (ii) whether visual accuracy was associated with the functional activity observed or characteristics of the physiotherapist.

METHODS

Thirty-four physiotherapists viewed and rated videos of squat, hand-over-head, forward bend functional activities and an artificial test condition (a reference movement followed by subsequent movements showing random differences in peak angle from 0° to 15°, so 18 sets of paired videos per functional activity). They rated each range of movement (same/more/less) relative to the reference movement, while their visual tracking was continuously monitored. Accuracy was calculated (multilevel regression) using two thresholds - two correct out of three viewings (2/3) and three correct out of three viewings (3/3).

RESULTS

More than 80% of physiotherapists were able to detect 9° difference using the 2/3 threshold and 12° using the 3/3 threshold. There was no association (p > 0.05) between visual accuracy and experience, sex, or movement type, except when viewing shoulder abduction compared with knee flexion using the 3/3 threshold. The only association between accuracy and visual tracking characteristics was for assessing lumbar flexion, where use of more visual fixation areas and a shorter fixation time per area were more accurate.

CONCLUSION

Physiotherapists were consistently accurate at detecting changes of ≥12° in single-plane, low-speed functional activities. Visual accuracy was not explained by experience or sex, and rarely associated with functional activity type or visual fixation.

Validity of inertial measurement units for tracking human motion: a systematic review

Human motion is often tracked using three-dimensional video motion tracking systems, which have demonstrated high levels of validity. More recently, inertial measurement units (IMUs) have been used to measure human movement due to their ease of access and application. The purpose of this study was to systematically review the literature regarding the validity of inertial sensor systems when being used to track human motion. Four electronic databases were used for the search, and eleven studies were included in the final review. IMUs have a high level of agreement with motion capture systems in the frontal and sagittal planes, measured with root mean square error (RMSE), intraclass correlation coefficient, and Pearson's correlation. However, the transverse or rotational planes began to show large discrepancies in joint angles between systems. Furthermore, as the intensity of the task being measured increased, the RMSE values began to get much larger. Currently, the use of accelerometers and inertial sensor systems has limited application in the assessment of human motion, but if the precision and processing of IMU devices improves further, it could provide researchers an opportunity to collect data in less synthetic environments, as well as improve ease of access to biomechanically analyse human movement.

Evidence for the Effectiveness of Feedback from Wearable Inertial Sensors during Work-Related Activities: A Scoping Review

Background: Wearable inertial sensor technology (WIST) systems provide feedback, aiming to modify aberrant postures and movements. The literature on the effects of feedback from WIST during work or work-related activities has not been previously summarised. This review examines the effectiveness of feedback on upper body kinematics during work or work-related activities, along with the wearability and a quantification of the kinematics of the related device. Methods: The Cinahl, Cochrane, Embase, Medline, Scopus, Sportdiscus and Google Scholar databases were searched, including reports from January 2005 to July 2021. The included studies were summarised descriptively and the evidence was assessed. Results: Fourteen included studies demonstrated a 'limited' level of evidence supporting posture and/or movement behaviour improvements using WIST feedback, with no improvements in pain. One study assessed wearability and another two investigated comfort. Studies used tri-axial accelerometers or IMU integration (n = 5 studies). Visual and/or vibrotactile feedback was mostly used. Most studies had a risk of bias, lacked detail for methodological reproducibility and displayed inconsistent reporting of sensor technology, with validation provided only in one study. Thus, we have proposed a minimum 'Technology and Design Checklist' for reporting. Conclusions: Our findings suggest that WIST may improve posture, though not pain; however, the quality of the studies limits the strength of this conclusion. Wearability evaluations are needed for the translation of WIST outcomes. Minimum reporting standards for WIST should be followed to ensure methodological reproducibility.

Advanced rehabilitation technology in orthopaedics-a narrative review

INTRODUCTION

As the demand for rehabilitation in orthopaedics increases, so too has the development in advanced rehabilitation technology. However, to date, there are no review papers outlining the broad scope of advanced rehabilitation technology used within the orthopaedic population. The aim of this study is to identify, describe and summarise the evidence for efficacy for all advanced rehabilitation technologies applicable to orthopaedic practice.

METHODS

The relevant literature describing the use of advanced rehabilitation technology in orthopaedics was identified from appropriate electronic databases (PubMed and EMBASE) and a narrative review undertaken.

RESULTS

Advanced rehabilitation technologies were classified into two groups: hospital-based and home-based rehabilitation. In the hospital-based technology group, we describe the use of continuous passive motion and robotic devices (after spinal cord injury) and their effect on improving clinical outcomes. We also report on the use of electromagnetic sensor technology for measuring kinematics of upper and lower limbs during rehabilitation. In the home-based technology group, we describe the use of inertial sensors, smartphones, software applications and commercial game hardware that are relatively inexpensive, user-friendly and widely available. We outline the evidence for videoconferencing for promoting knowledge and motivation for rehabilitation as well as the emerging role of virtual reality.

CONCLUSIONS

The use of advanced rehabilitation technology in orthopaedics is promising and evidence for its efficacy is generally supportive.

The feasibility and validity of a wearable sensor system to assess the stability of high-functioning lower-limb prosthesis users

Introduction

Lower-limb prosthesis users (LLPUs) experience increased fall risk due to gait and balance impairments. Clinical outcome measures are useful for measuring balance impairment and fall risk screening but suffer from limited resolution and ceiling effects. Recent advances in wearable sensors that can measure different components of gait stability may address these limitations. This study assessed feasibility and construct validity of a wearable sensor system (APDM Mobility Lab) to measure postural control and gait stability.

Materials and Methods

Lower-limb prosthesis users (n=22) and able-bodied controls (n=24) completed an Instrumented Stand-and-Walk Test (ISAW) while wearing the wearable sensors. Known-groups analysis (prosthesis versus controls) and convergence analysis (Prosthetic Limb Users Survey of Mobility [PLUS-M] and Activity-specific Balance Confidence [ABC] Scale) were performed on 20 stability-related measures.

Results

The system was applied without complications; however missing anticipatory postural adjustment data points for nine subjects affected the analysis. Of the 20 analyzed measures output by the sensors, only three significantly differed (p≤.05) between cohorts, and two demonstrated statistically significant correlations with the self-report measures.

Conclusions

The results of this study suggest the clinical feasibility but only partial construct validity of the wearable sensor system in conjunction with the ISAW test to measure LLPU stability and balance. The sample consisted of high-functioning LLPUs, so further research should evaluate a more representative sample with additional outcome measures and tasks.

Design of a Low-Cost, Wearable Device for Kinematic Analysis in Physical Therapy Settings

BACKGROUND

Unsupervised home exercise is a major component of physical therapy (PT). This study proposes an inexpensive, inertial measurement unit-based wearable device to capture kinematic data to facilitate exercise. However, conveying and interpreting kinematic data to non-experts poses a challenge due to the complexity and background knowledge required that most patients lack.

OBJECTIVES

The objectives of this study were to identify key user interface and user experience features that would likely improve device adoption and assess participant receptiveness toward the device.

METHODS

Fifty participants were recruited to perform nine upper extremity exercises while wearing the device. Prior to exercise, participants completed an orientation of the device, which included examples of software graphics with exercise data. Surveys that measured receptiveness toward the device, software graphics, and ergonomics were given before and after exercise.

RESULTS

Participants were highly receptive to the device with 90% of the participants likely to use the device during PT. Participants understood how the simple kinematic data could be used to aid exercise, but the data could be difficult to comprehend with more complex movements. Devices should incorporate wireless sensors and emphasize ease of wear.

CONCLUSION

Device-guided home physical rehabilitation can allow for individualized treatment protocols and improve exercise self-efficacy through kinematic analysis. Future studies should implement clinical testing to evaluate the impact a wearable device can have on rehabilitation outcomes.

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

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.