A portable intelligent stretching device for treating spasticity and contracture with outcome evaluation

Abstract

A portable stretching device with intelligent control was developed to treat the spastic/contractured ankle of neurologically impaired patients and evaluate the outcome. The device stretched the ankle throughout the range of motion (ROM) to extreme dorsiflexion and plantar flexion until a specified peak resistance torque was reached with the stretching velocity controlled based on the resistance torque. Stretching velocity was adjusted constantly. It was slow at the joint extreme positions, making it possible to reach a larger ROM safely, and it was fast in the middle ROM so the majority of the treatment was spent in stretching the problematic extreme ROM. The ankle was held at the extreme position for a period of time to let stress relaxation occur before it was rotated back to the other extreme position. Furthermore, the device evaluated treatment outcome quantitatively in multiple aspects, including active and passive ROM, joint stiffness and viscous damping, and reflex excitability. Combined with ultrasonography, the device was used to evaluate changes in mechanical properties of the Achilles tendon-aponeurosis induced by the stretching. The intelligent stretching reduced spasticity and contracture, including increases passive and active ROMs, decreases in elastic stiffness and viscous damping, and increase in muscle force-generating capacity.