Variability and reliability of the pendulum test for spasticity using a Cybex II isokinetic dynamometer.

I undertook this study to determine the test-retest variability and reliability of the pendulum test for muscle spasticity performed with the Cybex II isokinetic dynamometer. Thirty patients, with intracranial lesions and hemiplegia of 15 days' to 3 years' duration, were tested four times, consecutively. With the patients lying supine, the angle of flexion, at which the knee first reversed direction after the leg was dropped, was measured on each goniogram from the dynamometer chart recorder. The mean differences between the angles of reversal and the angles of maximum possible knee flexion (the relative angle of reversal) for the first through the fourth trials were 27.2, 27.0, 26.3, and 25.6 degrees, respectively. The relative angle of reversal did not differ significantly between trials. The mean difference between the largest and smallest relative angle of reversal for each of the subject's trials was 6.1 degrees. The intraclass correlation coefficient between the relative angle of reversal for the four trials was .96. Because the test variability was not significant and because the correlation between trials was high, the test may merit broader application to patients with intracranial lesions. Further investigation of variability across days and after treatments is advised.