Isokinetic dynamometric technique for spasticity assessment.

This study was conducted to determine the feasibility of quantifying spasticity by measuring the resistance to passive movement using an isokinetic dynamometer. A quantifiable method was developed by determining the summation of the four consecutive resisting torque amplitudes during flexion and extension of the knee at specified speeds and range of motion. A more rigorous assessment was made by finding the slope of the linear regression curve of torque-velocity data. Although the values of maximum torque were higher in the spastic group than in the normal group, the difference was statistically significant only when the sum of the torque amplitudes was considered (P < 0.0028). Values of the maximum torque as well as the sum of the torque amplitudes increased in a linear fashion (r > 0.75) with increasing velocity. The slopes of the torque-velocity curves were greater in spastic subjects than in normal subjects. The sensitivity to the rate of stretch was statistically greater (P < 0.0004) for the spastic group than normals only when the sum of torque amplitudes was considered. The corresponding data obtained during the flexion and extension of the knee were not statistically different (P > 0.05). Serial summation of torque amplitudes and measurement of slope in the torque-velocity curve are sensitive and repeatable methodologies for the measurement of spasticity assessment.