A Study of Hydraulic Ankles

Over a decade after challenging conventional wisdom, new scientific evidence continues to be published on the medical advantages of hydraulic ankles.

In humans, each foot is composed of 26 bones – together making up 25% of all the bones in the whole body. In addition, the foot also contains 30 different joints and more than a hundred muscles, tendons and ligaments. This complex design allows us to move and balance over a variety of different surfaces, usually without even thinking about it.

The prosthetic foot has always been a much simpler design. It has long been based on the concept of storing and returning energy as efficiently as possible. This is achieved using carbon fibre spring-like elements which deform during weight acceptance, storing energy, which is then returned as the user pushes off with their toe. This helps to restore some of the propulsion that would ordinarily be provided by ankle muscles.

However, the ankle in such designs is usually fixed to ensure efficient energy transfer. This means that they rely on the flexibility of these spring-like elements to adapt to uneven ground. Previous studies have reported this lack of adaptation to be a drawback for conventional prostheses1, as such, most prosthetic users have some difficulty walking on ground that isn’t completely flat.

The introduction of hydraulic-damping ankles to address this was a controversial one, going against the teaching and understanding of prosthetic biomechanics at the time. How could this technology be of benefit to the user when it affects the efficiency of energy return?

Clinical Studies Compendium

Clinical Compendium

This third edition compendium provides a summary of the scientific studies relating to our hydraulic ankle-foot products up to 2020. As such, it acts as a reference for patients, clinicians and health care providers, in order to help them make the most informed decision regarding their prescription.

Since the release of the previous compendium edition in 2014, the amount of new evidence for hydraulic ankles has grown significantly. This compendium includes 23 peer-reviewed journal publications describing the clinical benefits of hydraulic ankle technology, as well as nine key conference abstracts.

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