Wrist motion in handrim wheelchair propulsion

Prevalence rates of carpal tunnel syndrome (CTS) in the wheelchair user population are high. One of the possible causes of CTS in this population is the movement pattern of the wrist during handrim wheelchair propulsion, which could include large wrist joint angles and wrist/finger flexor activity. Combined with the repetitive character of the movement, this could, in time, be detrimental to the soft tissue of the wrist. To study peak wrist joint angles and their relationship with wrist- and finger-flexor activity, a three-dimensional (3-D) analysis of wrist movement during the push phase was performed. Nine subjects (five nonimpaired controls, four wheelchair users) propelled a handrim wheelchair 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 the wrist- and finger-flexor group were recorded. Average peak wrist joint angles during the push phase were: ulnar deviation, -24 +/- 11 degrees; radial deviation, 13 +/- 12 degrees; flexion, -14 +/- 18 degrees; and extension, 34 +/- 16 degrees. The values for ulnar and radial deviation were 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 degrees; flexion, -16 +/- 15 degrees; and extension, 32 +/- 16 degrees. The large deviation and extension angles, especially those recorded simultaneously 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.