Impact of Reach Height on Estimated Rotator Cuff Compression Risk in Manual Wheelchair Users With Spinal Cord Injury

Area of Science:

• Biomechanics
• Musculoskeletal Health
• Rehabilitation Science

Background:

• Reaching is a fundamental daily activity.
• Humeral elevation during reaching can lead to rotator cuff compression.
• Understanding this compression is crucial for manual wheelchair users with spinal cord injury (SCI).

Purpose of the Study:

• To estimate the risk of supraspinatus and infraspinatus tendon compression.
• To evaluate this risk relative to the acromion and coracoacromial ligament.
• To assess risk during reaching in manual wheelchair users with SCI.

Main Methods:

• Cross-sectional study with 8 participants (manual wheelchair users with SCI).
• Electromagnetic motion capture recorded shoulder kinematics during reaching tasks at two heights.
• Computed tomographic (CT)-based bone models and glenohumeral kinematics were used to evaluate tendon compression risk.

Main Results:

• Supraspinatus and infraspinatus tendons showed approximately 40% more activity duration (0.8 seconds) within 5 mm of scapular landmarks during low reaches compared to high reaches.
• This suggests a potentially increased risk of compression during lower reaching tasks.
• Results were consistent with prior studies on planar arm movements.

Conclusions:

• Estimating tendon compression risk, particularly using absolute time, can enhance understanding of cumulative exposure.
• Findings highlight potential biomechanical risks during daily reaching activities for individuals with SCI.
• Further research may inform interventions to mitigate rotator cuff compression in this population.