Design of a manual device to measure ankle joint stiffness and range of motion.

Abstract

Ankle joint stiffness and its range of motion (ROM) are commonly assessed to determine the appropriate mechanical characteristics required in an effective ankle-foot orthosis (AFO) prescription. The aim of this technical note is to present the design of a manual device that enables their convenient measurement in the clinical setting and to demonstrate its reliability. The manual device was designed with a torquemeter, a potentiometer, a steering wheel, a rotary plate, and a foot plate. The measurement of resistive torque at 0° (neutral), 5° (dorsiflexion) and 10° (dorsiflexion) ankle angular positions demonstrated the high reliability of the device with Intraclass Correlation Coefficient (ICC) (1,k) values over 0.97. Quantitative measurement of ankle joint stiffness and ROM by this manual device would provide objective information that could potentially assist AFO prescriptions. A future study should investigate how to incorporate the measurement obtained from the device into the prescription of an AFO.