DescriptionIn the US alone, more than 10,000 spinal cord injuries (SCI) are reported each year. Those who use a manual wheelchair (WC) depend upon their upper limbs to provide a means of locomotion during completion of their activities of daily living. As a result of greater than normal usage of the upper limbs, shoulder pain and pathology is common among manual wheelchair users (MWUs). The use of a patient-specific computational biomechanical model of WC propulsion may help guide rehabilitation that may improve clinical instruction and patient performance. The focus of the work will be two-fold: 1.) experimentally investigate the simultaneous kinematics, kinetics, and electromyography (EMG) throughout WC propulsion, and 2.) computationally, use these data for the creation and validation of a computational model examining resulting shoulder joint forces.
1.) Experimentally: An integrated data collection and analysis of kinematics, kinetics, and EMG data allow for the comparison of differences in WC propulsion between able-bodied and persons with paraplegia. Resulting muscle activity differences may be responsible for the observed kinematic and kinetic disparities between the two groups. The high incidence of shoulder pain in MWUs may be the result of such differences.
2.) Computational: When prescribing a WC, the use of a computational model may aide in determining an axle placement in which shoulder joint forces are at a minimum. Created from the information collected above, a patient-specific model was used to calculate the magnitude of shoulder joint forces throughout propulsion. In addition, results from a parametric study, determine the effect of axle placement on the magnitude of these forces. The overall goal is to find an ideal axle placement that minimizes the magnitude of these forces throughout propulsion.
In summary, the current patient-specific computational model can serve as a rehabilitative guide in WC prescription. With its ability to identify varying magnitudes of compressive loads in different axle positions, clinicians can target the resulting axle positions that minimize shoulder joint forces as an ideal set-up when prescribing a WC. In turn, minimizing joint forces from injury onset may prolong a MWU's pain-free propulsion and quality of life.