WRIST MOTION IN HANDRIM WHEELCHAIR PROPULSION

Prevalence rates of carpal tunnel syndrome (CTS) in the wheelchair use r population are high. One of the possible causes of CTS in this popul ation is the movement pattern of the wrist during handrim wheelchair p ropulsion, which could include large wrist joint angles and wrist/fing er flexor activity. Combined with the repetitive character of the move ment, this could, in time, be detrimental to the soft tissue of the wr ist. To study peak wrist joint angles and their relationship with wris t- and finger-flexor activity, a three-dimensional (3-D) analysis of w rist movement during the push phase was performed. Nine subjects (five nonimpaired controls, four wheelchair users) propelled a handrim whee lchair on a treadmill at three different velocities (0.83, 1.11, and 1 .39 m/s) and three slopes (1, 2, and 3%), while the surface EMGs of th e wrist- and finger-flexor group were recorded. Average peak wrist joi nt angles during the push phase were: ulnar deviation, -24+/-11 degree s; radial deviation, 13+/-12 degrees; flexion, -14+/-18 degrees; and e xtension, 34+/-16 degrees. The values for ulnar and radial deviation w ere close to normal values for maximal range of motion (ROM) found in the literature. Peak extension was approximately 50% of ROM. The peak angles, which occurred with concurrent activity of the wrist flexors, were: ulnar deviation, -22+/-11 degrees; radial deviation, 13+/-10 deg rees; flexion, -16+/-15 degrees; and extension, 32+/-16 degrees. The l arge deviation and extension angles, especially those recorded simulta neously with wrist flexor activity, are serious risk factors for CTS. This finding may help explain the high rates of CTS in the wheelchair user population.