Evaluation of safety and reliability in an infant reciprocal walking orthosis

In response to new demands for infant walking orthoses consideration was given to the development of a device for this category of patient. A specially developed hip joint with the required structural properties (Woollam et al., 2001) provided an opportunity for this development. Earlier structural assessment, and limited cyclic load testing of key elements of the orthosis (primarily the body brace), confirmed that a safe device for evaluation with patients could, theoretically, be produced. A provisional prototype was therefore designed and manufactured for initial structural testing of the complete infant orthosis (Stallard et al., 2001). Efficiency of walking is strongly influenced by the lateral rigidity of the orthosis. Monitoring the structural performance of the provisional infant design indicated it would equal or improve on the stiffness of that achieved in the adult specification. Additionally, relative strength was comparable with the adult version, which has proven to be safe and reliable in many years of routine prescription. This, together with the limited cyclic testing of the complete orthosis (Stallard et al., 2001), gave confidence that it was safe to proceed with controlled field evaluation of the infant design when supplied as a rehabilitation engineering device within the provisions of an ISO9001 and EN46001 QA System. This additional study of controlled patient use, and further representative cyclic load testing in parallel with the field evaluation, had established the long-term structural safety of the orthosis. Wider application is now to be introduced through completion of the EC (European Community) Medical Devices Directive formalities.