Design and mechanical testing of an adjustable posterior leaf spring ankle-foot orthosis for patients with drop foot

Objectives: This study aimed to design an adjustable posterior leaf spring (PLS) ankle-foot orthosis (AFO) with an affordable material in low-income countries and investigate the mechanical properties between an adjustable PLS AFO and a standard PLS AFO. Study Design: Static and dynamic mechanical testing. Methods: This study preliminarily tested a new adjustable PLS AFO against a standard PLS AFO. Each AFO design was tested with mechanical testing using an Instron 8801 universal testing machine. Results: The stiffness value of the adjustable PLS AFO was greater than that of the standard PLS AFO during the static loading test. The energy dissipated ratios were lower in the adjustable PLS AFO than in the standard PLS AFO. After 110,000 cycles of fatigue testing, the distal rivet of the adjustable PLS AFO became loose, although the standard PLS AFO had no problem. Conclusions: The novel adjustable PLS AFO achieved noninferior mechanical properties except fatigue strength. The connecting area always initiated fatigue failure. It is suggested that this area must be prevented for stress concentration. As a preliminary study, this study is fundamental for future studies.