Reproducibility of isokinetic test findings for assessment of wrist spasticity in stroke patients

We aimed to determine the test-retest reproducibility of isokinetic dynamometric measurement of the resistance to passive motion for quantitative evaluation of wrist flexor spasticity in stroke patients. In a repeated measures design, 2 raters tested each subject 3 times on 6 separate days. Twenty one sub-acute/chronic stroke patients 55 +/- 14.1 years of age with an average disease duration of 7.04 +/- 2.87 months volunteered to take part along with 20 age-matched healthy controls. Clinical assessment of spasticity was performed using an Ashworth Scale. Resistance measurements of 5 consecutive flexion/extension movements of the wrists were performed at 3 reselected angular velocities ( 10 degrees/ s, 30 degrees/ s, 45 degrees/ s), using a computerized dynamometer, set in the continuous passive joint motion mode. The maximum peak torque values in for each subject were calculated for each set of repetitions. The reproducibility of strength measurements were evaluated using single-measure and average-measure intra class correlation coefficients ( ICCs). There was a significant positive correlation between Ashworth Scale and torque values. Torque values were significantly higher in groups with patients who had strokes than in the control group. The dynamometric scores were positively correlated with Ashworth Scale grades. The ICCs for intra-tester measurements were high and ranged 0.82-0.87. The Bland-Altman plots indicated no systematic bias. The standard error of measurement ( SEM) ranged 0.27-0.38 Nm while the smallest real difference ( SRD) ranged -1.0 Nm to 1.1 Nm). These values correspond to a mean SEM% of 31% and SRD% of 85%. These values indicate relatively large measurement error and thus does not support the use of isokinetic dynamometry, using this protocol and measurement system, in assessing wrist muscles spasticity in stroke patients.