Inertial Measurement Unit–Derived Ergonomic Metrics for Assessing Arm Use in Manual Wheelchair Users With Spinal Cord Injury: A Preliminary Report

Top Spinal Cord Inj Rehabil, 2021 · DOI: 10.46292/sci20-00059 · Published: July 1, 2021

Spinal Cord Injury Occupational Health Rehabilitation

Simple Explanation

This study uses wearable sensors (IMUs) to measure how manual wheelchair users (MWC) with spinal cord injury (SCI) use their arms during daily activities. The study looks at 'risk' (arm elevated >60°) and 'recovery' (static arm posture <40° for ≥5 seconds) metrics derived from the RAMP II to see if they can differentiate MWC users with SCI from able-bodied individuals. The study also investigates if these metrics can differentiate MWC users who experienced rotator cuff pathology progression over one year from those who did not.

Study Duration

1 year

Participants

34 MWC users with SCI and 34 age- and sex-matched able-bodied individuals

Evidence Level

Longitudinal study

Key Findings

1
MWC users had a higher frequency of risk events, summated duration of recovery events, and duration of each recovery event compared to able-bodied participants.
2
MWC users with rotator cuff pathology progression had longer summated durations and higher frequencies of risk events, and larger risk to recovery ratios compared to those without progression.
3
MWC users with pathology progression had shorter summated durations and lower frequencies of recovery events.

Research Summary

This study investigated risk and recovery metrics derived from IMUs to differentiate arm use between MWC users with SCI and able-bodied individuals, and to compare MWC users with and without rotator cuff pathology progression. The study found that MWC users had higher frequencies of risk events, while those with pathology progression had longer durations of risk events and lower durations of recovery events. The study concludes that IMU-derived metrics quantifying arm use at postures >60° and risk to recovery ratios may provide insights of potential risk factors for rotator cuff pathology progression.

Practical Implications

Intervention Targets

Metrics quantifying arm use at postures >60° and risk to recovery ratios may provide clinically relevant interventional targets.

Free-living Arm Use Monitoring

Arm use monitoring in a free-living environment may be able to identify arm use profiles that are protective of accelerated tendon aging.

Biofeedback Index

A multifactorial ratio (risk to recovery) could be utilized as a biofeedback index in interventional studies.

Study Limitations

1
Humerothoracic elevation angles and elevation planes relative to the thorax were not calculated.
2
One or two days of data were collected for participants, which might not be a reliable representation of their arm use throughout a week.
3
A larger sample size and longer follow-up are warranted to fully investigate the associations between risk and recovery metrics with the progression of rotator cuff tendon pathology.

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