Glenohumeral joint dynamics and shoulder muscle activity during geared manual wheelchair propulsion on carpeted floor in individuals with spinal cord injury

Trends and advancements in shoulder biomechanics research

The 12th International Shoulder Group (ISG) Conference was held at Mayo Clinic in Rochester, Minnesota, USA, from August 12-13, 2018, and was hosted by Dr. Melissa (Missy) Morrow of Mayo Clinic and Dr. Meghan Vidt of Pennsylvania State University. This conference was held as a satellite conference to the annual 2018 American Society of Biomechanics Conference. This Editorial accompanies the Special Issue of the Journal of Electromyography and Kinesiology, and contains a selection of the work presented during the 12th Meeting of the ISG. Fourteen full-length articles describe advancements in shoulder research relevant to both basic science and clinical outlets. The work presented herein spans the research areas of methodology, mechanistic understanding, and clinical management. These areas are synergistic and equally important to propel the field forward and enhance impact. These manuscripts reinforce the dedication of the ISG and its members and showcase the ongoing drive toward translational application of these concepts across the common themes of rotator cuff, muscle, wheelchair & ergonomics, and methods & modeling. Highlights of each of the special issue publications are described within the context of the current trends in shoulder research and areas for further advancement.

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

Background:

Individuals with spinal cord injury (SCI) who use manual wheelchairs (MWCs) have a higher rate of rotator cuff pathology progression than able-bodied individuals.

Objectives:

This study aimed to test the ability of risk and recovery metrics of arm use to differentiate between (1) MWC users with SCI and matched able-bodied participants (cross-sectional matched-sample study) and (2) MWC users with rotator cuff pathology progression over 1 year from those without pathology progression (longitudinal study).

Methods:

Thirty-four MWC users and 34 age- and sex-matched able-bodied individuals were recruited. Upper arm risk (humeral elevation >60°) and recovery (static ≥5 seconds and humeral elevation <40°) metrics were calculated from wireless inertial measurement units (IMUs) worn on the upper arms and torso in the free-living environment. Two separate magnetic resonance imaging studies were completed and assessed for a subset of 16 MWC users approximately 1 year apart.

Results:

The frequency of risk events (p = .019), summated duration of recovery events (p = .025), and duration of each recovery event (p = .003) were higher for MWC users than able-bodied participants. The summated duration of risk events (p = .047), frequency of risk events (p = .027), and risk to recovery ratio (p = .02) were higher and the summated duration of recovery events (p = .036) and frequency of recovery events (p = .047) were lower for MWC users with rotator cuff pathology progression (n = 5) compared to those without progression (n = 11).

Conclusion:

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.