Reliability of isokinetic measurements of ankle dorsal and plantar flexors in normal subjects and in patients with peripheral neuropathy

Objective: To establish a reliable method for evaluation of motor performance of ankle dorsal and plantar flexors in healthy subjects and in patients with peripheral neuropathy. Design: Thirty-eight control subjects and 7 patients with peripheral neuropathy were studied. All patients and 25 control subjects were tested twice. Patients and Control Subjects: An outdoor clinic sample of 7 patients with hereditary motor sensory neuropathy (HMSN) and 38 control subjects. Main Outcome Measures: The effect of a rest interval, a displacement of the axis of rotation, examination by three investigators on the peak torque and work of dorsal and plantar flexors, and the percentage difference at test-retests. Results: Control subjects had percentage differences of 5.6% and 8.0% for dorsal flexion and 3.8% and 8.7% for plantar flexion at 60 degrees/sec and 180 degrees/sec, respectively. In neuropathic patients the percentage differences were 0% and 8.6% for dorsal and 5.1% and 12.3% for plantar flexion at 30 degrees/sec and 60 degrees/sec, respectively. No interindividual differences between 3 investigators were found. A rest interval between trials resulted in an increased plantar flexion peak torque (P < .05). Displacement of 1.5cm of the axis of rotation resulted in a change of the peak torque of 8.3% for plantar flexion (P < .01). Conclusions: A well-defined test protocol for isokinetic motor performance of the ankle dorsal and plantar flexors provides a reliable procedure for quantification of motor function in healthy subjects and in patients with HMSN1. (C) 1996 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation