The Influence of Sex on Upper Extremity Joint Dynamics in Pediatric Manual Wheelchair Users With Spinal Cord Injury.

Introduction: Manual wheelchair propulsion is a physically demanding task associated with upper extremity pain and pathology. Shoulder pain is reported in over 25% of pediatric manual wheelchairs users, and this number rises over the lifespan. Upper extremity biomechanics in adults has been associated with shoulder pain and pathology; however, few studies have investigated upper extremity joint dynamics in children. Furthermore, sex may be a critical factor that is currently unexplored with regard to pediatric wheelchair mobility.

Objectives: To investigate differences in upper extremity joint dynamics between pediatric male and female manual wheelchair users with spinal cord injury (SCI) during wheelchair propulsion.

Methods: Novel instrumented wheelchair hand-rims synchronized with optical motion capture were used to acquire upper extremity joint dynamics of 20 pediatric manual wheelchair users with SCI (11 males, 9 females). Thorax, sternoclavicular, acromioclavicular, glenohumeral, elbow, and wrist joint kinematics and kinetics were calculated during wheelchair propulsion. Linear mixed models were used to assess differences between sexes.

Results: Females exhibited significantly greater peak forearm pronation ( p = .007), normalized wrist lateral force ( p = .03), and normalized elbow posterior force ( p = .04) than males. Males exhibited significantly greater peak sternoclavicular joint retraction ( p < .001) than females. No significant differences between males and females were observed for the glenohumeral joint ( p > .012).

Conclusion: This study found significant differences in upper extremity joint dynamics between sexes during manual wheelchair propulsion. Our results underscore the importance of considering sex when evaluating pediatric wheelchair mobility and developing comprehensive wheelchair training interventions for early detection and prevention of upper extremity pain and pathology.