No abstract

A systematic integrated data collection and analysis of kinematic, kinetic, and electromyography (EMG) data allow for the comparison of differences in wheelchair propulsion between able-bodied individuals and persons with paraplegia. Kinematic data from a motion analysis system, kinetic data from force-sensing push rims, and electromyography data from four upper-limb muscles were collected for ten push strokes. Results are as follows: Individuals with paraplegia use a greater percentage of their posterior deltoids, biceps, and triceps in relation to maximal voluntary contraction. These persons also reached peak anterior deltoid firing nearly 10 deg earlier on the push rim, while reaching peak posterior deltoid nearly 10 deg later on the push rim. Able-bodied individuals had no triceps activity in the initial stages of propulsion while their paraplegic groups had activity throughout. Able-bodied participants also had, on average, peak resultant, tangential, and radial forces occurring later on the push rim (in degrees). There are two main conclusions that can be drawn from this integrative investigation: (1) A greater "muscle energy," as measured by the area under the curve of the percentage of EMG throughout propulsion, results in a greater resultant joint force in the shoulder and elbow, thus potentially resulting in shoulder pathology. (2) Similarly, a greater muscle energy may result in fatigue and play a factor in the development of shoulder pain and pathology over time; fatigue may compromise an effective propulsive stroke placing undue stresses on the joint capsule. Muscle activity differences may be responsible for the observed kinematic and kinetic differences between the two groups. The high incidence of shoulder pain in manual wheelchair users as compared to the general population may be the result of such differences, although the results from this biomedical investigation should be examined with caution. Future research into joint forces may shed light on this. Further investigation needs to focus on whether the pattern of kinematics, kinetics, and muscle activity during wheelchair propulsion is compensatory or evolutionary by tracking individuals longitudinally.

In the United States alone, more than 10,000 spinal cord injuries (SCI) are reported each year. This population depends 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, proper propulsion mechanics are paramount in preventing injuries. Upper limb pain and pathology is common among manual wheelchair users due to the requirements placed on the arms for wheelchair locomotion. During the wheelchair rehabilitation process following an SCI, an individual is prescribed a wheelchair (WC). 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 overall goal of this study is to develop and refine a computational model that may aide in minimizing shoulder pathology.

No abstract

Pain throughout wheelchair (WC) propulsion is a very real fact of life for individuals who use a manual WC as their primary means of locomotion. A number of studies have reported the prevalence of shoulder pain in manual wheelchair users (MWU’s) ranging between 30–73% [1, 2]. Questions exist as to what may cause the extent of such shoulder pain. It is possible that a lack of education on proper propulsion techniques leads to poor propulsion habits that can be detrimental to overall shoulder health. It is also possible that such acquired techniques translate into shoulder joint forces whose repetition and magnitude may be so high that they are injurious to the user.