The Ankle Foot Orthosis is designed to be modular or custom made, and a clinician can send either a 3D scan or a plaster model. If they choose a plaster model, they will scan the cast to obtain a virtual image. The design allows for changes in dimension of the calf section and foot plate, as well as adjustments to the diameter of the rods that make up the leaf spring to influence the control that the device provides.

The device is primarily designed for individuals who have a neurological condition such as multiple sclerosis or complications arising from a cerebrovascular accident (CVA), which affect muscle control in the lower limbs, particularly in the dorsiflexion muscles. These muscles help provide ground clearance of the foot during the swing phase of gait, prevent the foot from slamming to the ground at initial contact, and also provide some push off at the end of gait.

Crispin Orthotics’ specialists have designed this orthosis to prevent the foot from dropping downward during the swing phase of gait. The leaf spring at the back of the device supports the weight of the foot, and upon initial contact, the ground reaction force creates a flexion movement of the leaf spring, allowing a controlled downward progression of the footplate to prevent the foot from slamming to the ground. Upon progression of gait towards terminal contact, the footplate acts as a leaf spring and stores energy to provide some assistance prior to initiating the swing phase. In addition to the control element of the orthosis, they have designed the leaf spring to incline forward to increase the control and preclude the use of a calf strap, thus making the device more cosmetic, lightweight, and cost-effective. The device can be prescribed in the United Kingdom by a state-registered orthotist.

Specialists have tested the device using HP 3D HR PA 12 and have completed more than 500,000 cycles of repetitive loading without any visual changes within the properties of the orthosis. They are also conducting controlled tests of the orthosis to ascertain its effectiveness for long-term use.

Within the orthotics industry, it is not possible to create a dynamic ankle foot orthosis without using carbon fiber. The carbon fiber system used in orthotics is weaker in compression than the HP 3D HR PA 12 materials used with HP Multi Jet Fusion technology.

Carbon fiber is also non-adjustable, not environmentally friendly, difficult to finish, and very expensive to produce, all problems that can be solved using HP Multi Jet Fusion.

The dynamic 3D printed ankle foot orthosis costs 50% less than producing a carbon fiber product, and Crispin is confident that the device they have designed is more cosmetic and more accurate in fit due to the digital manufacturing process.