The clinical application of a novel instrumented wheelchair pushrim

Sustained manual wheelchair propulsion is related to shoulder injury, which is associated with increasing age and time as a wheelchair user. Consequently, the biomechanics of manual wheelchair propulsion have been widely examined, both to quantify the demand of a task and also to guide optimisation of technique. Such analysis has incorporated assessment of push rim kinetics using instrumented wheelchair wheels. The major limitation of the instrumented wheels currently available is that they add significant weight to the wheelchair, increasing the demand on the user and altering propulsion biomechanics. This thesis presents the design and potential clinical application of a novel lightweight instrumented wheelchair wheel, the ‘Sensewheel’. In this thesis, the Sensewheel is used to investigate the influence of ageing on propulsion biomechanics and to quantify shoulder joint demand during various types of over ground propulsion. Propulsion demand is quantified with the use of surface electromyography and a musculoskeletal model of the trunk and upper limbs, animated with data collected from the Sensewheel. The Sensewheel is also used to identify pushing technique differences during over ground propulsion, and also to provide real time feedback as a training intervention to improve technique. This thesis consists of a series of short clinical studies exploring the use of the Sensewheel. The design and measurement capabilities of the Sensewheel are introduced, alongside discussion of current limitations and future development requirements. The first experimental study investigates age related differences in propulsion biomechanics and muscle activity levels during wheelchair propulsion on a treadmill. The results of the study are not conclusive in supporting the theory that older wheelchair users are at greater risk of injury due to greater relative muscle demand. The second experimental study examines shoulder joint demand during level, 2.5% cross slope, 6.5% and 12% incline over ground propulsion. The results demonstrate significantly greater levels of shoulder joint demand during incline propulsion, with glenohumeral (GH) joint contact force rising above 2000N and muscle activity levels rising to 92% of maximum during the 12% incline task. The results also demonstrate a strong positive correlation between force applied at the wheelchair push rim and resultant GH joint contact force. The third experimental study compares the propulsion technique of novices and experts during the same over ground propulsion tasks. The results demonstrate that the experts are able to use the force they apply to the push rim more effectively to reduce the repetition of the task, but that during more challenging tasks this may increase shoulder joint demand. A systematic review of the literature identifies that push rate and push arc can be successfully optimised using real time feedback. The fourth experimental study describes how the Sensewheel is used to provide real time data to inform real time verbal feedback to novice non wheelchair users, with the goal of optimising push arc. The intervention is successful in increasing push arc, reducing the number of pushes required whilst maintaining shoulder joint load within the range of normal daily activity. In summary, the thesis introduces the various potential clinical applications of a novel lightweight instrumented wheelchair wheel. In this thesis, the Sensewheel is used to assess the extent of the shoulder demand experienced during manual wheelchair propulsion, and to identify the importance of optimising pushing effectiveness. It is also used to successfully provide an intervention to improve propulsion technique