An isometric hand tester: quantifying motor function in the hand

The aim of this study was to develop and assess an isometric hand tester to measure multiple strength parameters of the muscles of the hand. Nineteen men and 22 women took part in a first study and 17 men were tested in a second one. Five different tests were developed: wrist flexion, wrist extension, metacarpophalangeal joint flexion, thumb adduction and proximal and distal interphalangeal joint flexion. Reliability was tested with an intraclass correlation coefficient for single measures. When the results from men and women were analysed separately, all tests except metacarpophalangeal joint flexion and thumb adduction produced intraclass correlation coefficients greater than 0.7. Combining the genders gave intraclass correlation coefficients greater than 0.9 except for metacarpophalangeal joint flexion and thumb adduction. After adjustments, intraclass correlation coefficients for metacarpophalangeal joint flexion and thumb adduction were between 0.70 and 0.83 in the second study. The new isometric hand tests improve the measurement of intrinsic and extrinsic hand muscle strength.