Abstract
The purpose of this study is to develop a clinically applicable method for quantitative evaluation of the ankle joint spasticity. Spasticity has bad influence on gait of hemiplegia, therefore it is important to estimate spasticity and to reduce it efficiently. Skeletal muscle spasticity is assessed by physical therapists as increased resistance of a particular muscle group to manually induced passive movement.
In this study the passive movement was produced by the gravitational force (2.0 kilogram weight) and we recorded the response of the ankle joint. The subjects consisted of 3 healthy individuals and 11 hemiplegic individuals with slight, moderate, and severe spasticity of ankle joint muscles. In healthy subjects the foot was dorsally flexed with smooth manner and little electromyogram (EMG) appeared when the subject was fully relaxed. But in severe spastic subjects the foot movement oscillated and the EMG appeared at each dorsal flexion of the ankle joint. The quantitative measurement of spasticity could be defined by the characteristics of the ankle goniogram. Evaluation index which we proposed showed a good agreement with clinical evaluation. In addition, mathematical model of the ankle joint movement given by this test was developed supporting the evaluation index. The simulated results revealed that on the severer spastic patients, muscle spindle excitability for passive stretch increased and ankle joint viscosity was decreased.
