unique orthopaedic devices

Are adjustable ankle AFO’s the future?


“We can rebuild him. We have the technology. We can make him better than he was. Better, stronger, faster.”

If you’re old enough to remember the above quote from the 1974 six million dollar man (currently 30 million with inflation) it was pure sci-fi that we could rebuild and restore limbs with identical biomechanical function.  It seems prosthetics are leaps ahead of orthotics in terms of R & D, with progress made year on year and technology filtering down to clinicians. I would suggest watching the several TED talks from amputee and MIT professor Hugh Herr on his neuro embodied design principals – prosthetics are closing in on replicating normal spatiotemporal parameters and ankle joint kinematics / kinetics, alongside proprioceptive integration.

Depending on the patient’s pathological gait, the Orthotists goal is to align the orthosis to provide the required lever effect whilst resisting / assisting motion where required, often with a reliance of ground reaction forces to assist in correction of the phases of gait.

Where it becomes challenging for the Orthotist is that it has become difficult to produce a perfectly effective orthosis due to the lack of adjustment options, and limitations of materials; although 3D printing does open up some interesting options. Do we get close? Yes. Do we mimic perfectly normal pathological gait? No, and how could we? We rely on tuning in conjunction with further modifications to footwear in order to try and optimise as close to the pathological gait as possible.  Somewhere a compromise is made.

Since all current AFO treatment options have their pros and cons. Almost all current AFOs limit plantar flexion and make it difficult to achieve the best possible compromise of dorsiflexion assist effect if available, energy storage for push off, and heel strike loading response.

In theory if we can match the spatiotemporal parameters and ankle joint kinematics / kinetics, then the correct cerebral connections are established through motor impulses and in some cases we have the potential for single muscle groups to be strengthened resulting in gait that is much closer to a physiological one.

With an adjustable ankle joint it can constantly be adapted to the patient’s rehab. The ability to lock / unlock, control dorsiflexion and plantarflexion ROM, and regulate dorsiflexion vs plantar flexion assistance has to be the future for articulating AFO’s. Currently Fior & Gentz are leading this methodology and technology with good results from Neuro swing.

Do we have evidence favouring the adjustable articulating AFO’s over non-articulating? It certainly seems strong, but still very limited; I would suggest reading articles by Yamamoto, Singer, Kobayashi, Kerkum, and Shabbagh.

What are your thoughts on this developing technology? Has anyone had any experience of actual objective data with regard to adjustable articulating AFO’s? As Orthotists we are largely under resourced in clinic and have to rely largely on subjective data, so any comments on this topic would be welcome.