Measurement of the car steering wheel turning force of persons with cervical cord injuries.

Steering wheel turning force was measured in persons with cervical cord injuries for evaluation of their ability to drive a car. Seventeen subjects were divided into two groups according to their functional level: Group I (comprising 11 subjects of functional level C6) and Group II (comprising 6 subjects of functional level C7-C8). A device for hand fastening was attached to a steering wheel, which was mounted onto the rotation shaft of a Cybex machine, and the torque for turning the wheel with the right hand at a constant speed was measured. Persons with cervical cord injuries showed characteristically higher left-turning torque than right-turning torque. Mean values and standard deviation of the two groups were: 0.52 +/- 0.16 kgf-m (left-turning) and 0.40 +/- 0.12 kgf-m (right-turning) for Group I; and 0.81 +/- 0.16 kgf-m (left-turning) and 0.76 +/- 0.15 kgf-m (right-turning) for Group II. Subjects in Group I had a turning torque lower than 0.30 kgf-m (the lowest wheel turning torque shown by Japanese cars equipped with a power-steering system) at a turning angle range of between 0-135 degrees in left-turning and 45-200 degrees in right-turning.