Some Biomechanical Considerations in the Design of Ankle-foot Orthoses

The proliferation of new designs for anklefoot orthoses fabricated with thermoplastic materials presents a bewildering picture for the clinician faced with the prescribing of a particular device for an individual patient. Indeed, the orthotics specialist with his spe­ cial knowledge may require to adopt a trial and error policy extending over a consider­ able number of patients before the advant­ ages of the various designs become apparent and a practical prescription philosophy can be formulated. T w o important factors that appear to gov­ ern the success or failure of a fitting with a particular device are the accuracy with which the patient's requirements have been assessed and the ability of the device to ful­ fill these requirements. A successful orthotic prescription may thus be considered as a process of patient-orthosis matching involv­ ing measurement of the patient's functional deficit and selection of an orthosis whose characteristics, also determined by measure­ ment, are such as to reduce the patient's defi­ cit to the minimum.