The ankle joint is an important part of the body which is responsible for normal gait cycle. Dorsiflexion, plantar flexion, inversion and eversion are four types of movements controlled by the ankle joint. All these movements are controlled by the ligaments and the muscles associated with the ankle. Disorders of these ligaments and muscles leads to ankle dysfunction.

The hysteresis concept was employed to determine if there is any ankle dysfunction. A recently developed device, the Ankle Torsion Monitor (AnTm) was employed to evaluate the viscoelasticity and stiffness of the ankle joint. The greater the hysteresis loop area (HLA) the more inelastic is the ankle joint. Similarly the greater the Range of Motion (ROM), the less stiff is the ankle joint. Nineteen subjects (12 control and 7 patients) were examined to evaluate their viscoelastic properties and passive ROM of the ankle joint. The control subjects were given four different types of exercises; it was found that these exercises are considered to be suitable to improve the viscoelasticity of their ankle joints, although there was variation in the results of four exercises.

A mathematical model was also developed to determine the elastic constants such as stiffness, damping and friction. This model could be employed for each individual subject based upon the experimental results obtained by using the AnTm. The values obtained can be used for designing ankle braces that will give strength to the ankle joint for preventing falls.