Preferred elbow position in confined wheelchair configuration

High mechanical load leads to pain and damage in the upper extremities of wheelchair users. Wheelchair users suffer a limited range of motion of the upper extremities due to the confining wheelchair configuration. This is a key factor affecting the efficiency of wheelchair propulsion and upper extremity loading. With a view toward further understanding the interaction between the user and wheelchair, this study identifies the accessible workspace of the elbow under conventional wheelchair design and identifies the actual location and range of motion of the elbow during wheelchair propulsion. An eight-camera motion analysis system recorded the kinematics of 14 non-experienced wheelchair users. Users under standardized conservative wheelchair-sitting position moved their right elbow as widely as possible at five different wheel angles while elbow positions were recorded, thereby establishing the maximum possible elbow workspace. Actual positions of the right elbow were recorded during wheelchair propulsion. The arc angles of the elbow workspace range from 68.8 degrees to 83.4 degrees and are located at the lateral and posterior quadrant of the circle on which the elbow trajectories located. Reachable workspace is smaller when the hand holds the hand rim at a larger wheel angle. The preferred positions for propulsion are located approximately 2/3's of the way through the total workspace. The obtained data will be useful for improved wheelchair design and biomechanical modeling of the wheelchair/user system.