Abstract
An Ankle-Foot Orthosis (AFO) is a device that prescribed to assist patient during recovering of lost functions, and at the same time, to protect the ankle-foot from further injuries when patients are in motion. Currently, polypropylene is the most popular thermoplastic for all kinds of custom-made orthoses. It has the characteristics of low weight, high strength, high fatigue resistance and excellent molding capabilities. However, there are too many pre-manufacturing parameters such as the thickness and curvatures required that makes the quality control impossible. Supan and Hovorka (1995) studied the thermoplastic Ankle-Foot Orthoses adjustments/replacements in young cerebral palsy and spina bifida patients. Six types of thermoplastic AFOs were tested. They found that neuromusculoskeletal functional status appears to determine the AFO design and its replacement. Chu, et al., (1997) developed an experimental method that studied the stress changes in the AFO due to AFO geometry changes. The goal of this project is to quantify the stress changes associated with a series of body weights and motion change; thus, to determine if the resulting stresses are of such magnitude as to potentially result in fractures and destruction of the AFOs.