The Habilitation Technology Laboratory at Gillette Children's Hospital has developed two designs for durable “short” double-flexure type ankle joints. Flexure elements, singly and in multiples, have been used for centuries to create hinges. Some of the earliest hinges were of animal hides and used for doors and lids. In recent decades, long (flexure length-to-thickness ratios greater than 5-to-1) plastic flexures have been used as a bridge between thigh, calf and foot sections of fracture orthoses. Those designs were unstable when subjected to varus, valgus, torsional or longitudinal loading, and, because of that, gave a poor impression of the potential value of flexure designs in orthotics. At Gillette, we have been developing and using short (flexure effective length-to-thickness ratios less than 2-to-1) double-flexure orthotic joints since 1976. The short flexure design solves the structural instability problems but magnifies fatigue durability problems. We have designed a testing apparatus which simultaneously subjects four ankle-foot orthoses to service cycle repetitions. This has helped to determine more quickly and objectively which designs and materials are more durable. The double-flexure design approach retains the weight and cosmetic advantages of plastic orthoses while providing several advantages over the posterior leaf design. The flexures can be located for full congruency at anatomic and orthotic joint axes. The desired ankle range-of-motion is almost totally free of resistance, and the degree of motion restraint can be easily and precisely controlled. Gillette has provided several thousand ankle-foot and knee-ankle-foot orthoses utilizing these ankle joints. Utilization has been in a wide variety of diagnoses among adults as well as children.