Differences in Glenohumeral Joint Contact Forces Between Recovery Hand Patterns During Wheelchair Propulsion With and...

Area of Science:

• Biomechanics
• Rehabilitation Engineering
• Musculoskeletal Health

Background:

• Manual wheelchair users (MWCU) frequently experience shoulder pain and injuries, often linked to impingement.
• Propulsion hand patterns influence shoulder loading and injury susceptibility in MWCU.
• The impact of specific shoulder muscle weakness on shoulder loading remains unclear.

Purpose of the Study:

• To compare glenohumeral joint contact forces (GJCFs) across different wheelchair propulsion hand patterns.
• To investigate how GJCFs change with weakness in primary shoulder muscle groups.
• To identify hand patterns and muscle strengthening strategies that may reduce shoulder injury risk in MWCU.

Main Methods:

• Musculoskeletal modeling and simulation were employed to analyze GJCFs.
• Experimental data classified MWCU into four distinct hand pattern groups.
• Simulations assessed baseline strength and six muscle weakness conditions for each hand pattern.

Main Results:

• The semicircular hand pattern demonstrated consistently lower shear GJCFs compared to other patterns.
• The double-loop pattern exhibited the highest superior GJCFs, while the single-loop pattern showed the highest anterior and posterior GJCFs.
• Weakening internal and external rotators significantly increased shear GJCFs and decreased compressive GJCFs.

Conclusions:

• The semicircular hand pattern may reduce the risk of shoulder injuries like subacromial impingement.
• Strengthening rotator cuff muscles, particularly internal and external rotators, is vital for mitigating shoulder overuse injuries in MWCU.
• Understanding hand patterns and muscle function is key to preventing shoulder pathologies in manual wheelchair users.