Although ankle replacements were first implemented about 30 years ago, it is only recently that they have become popular. The design of the implants improved in the 1980’s and a ‘third generation’ of implants have been in use for up to 10 years.
Ankle replacement involves replacing the natural surfaces of the ankle joint which have degenerated
The results of ankle replacement today are generally good and the outcome of ankle replacement from a functional standpoint is thought to be better than that of an arthrodesis or fusion as patients with a successful ankle replacement are able to do day-to-day activities more easily than those who have had ankle fusion surgery. Ankle replacement patients tend to walk with a more normal gait and stresses on the other joints next to the ankle are reduced. Following an ankle fusion there is evidence of degeneration or wear and tear in the joint next to the ankle in all patients – an ankle replacement aims to reduce this risk considerably.
Ankle replacement involves replacing the natural surfaces of the ankle joint which have degenerated with an artificial cover known as a prosthesis.
The current ankle replacement has three components. There is one on the tibia, one on the talus and there is a third, mobile component. This allows for greater movement and reduces the stress between the bone and the implants.
The component which covers the part of the ankle joint known as the tibia is flat. It is integrated into the bone with a short stem. The component which covers the part of the ankle joint known as the talus is curved and fixed into place with pegs. These components are covered in a bioactive coating which encourages the patient’s own bone to grow into the artificial fixtures.
This type of operation allows the patient to preserve the movement that they have and often (but not always) gain a few degrees. The use of a mobile plastic bearing means the prosthesis is under much less stress and should, other things being equal, stay in place longer than the old two-part ankle joint replacements.
However, like knee and hip joints, an ankle replacement will eventually wear out and need to be replaced or the patient might have ankle fusion surgery. Currently the series of the third generation of ankle replacements suggest that over 80% will still be in place after 10 years.