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Information on ankle replacement and some frequently asked questions

Ankle Replacement

The ankle is a hinge joint made up of three bones, which are connected by muscles, ligaments and tendons. These bones are:

  • the talus, which is the ankle bone,
  • the tibia, which is the large shin bone,
  • the fibula, which is the smaller shin bone, located next to the tibia.

The bones at the articular surface are covered with a protective ‘shock absorber’ articular cartilage. The whole joint is enclosed in a joint capsule which is lined with a protective lining, called the synovium, which produces a lubricant called synovial fluid.

What is an ankle replacement?

An ankle replacement, often referred to as an ankle implant or device implant is, in more basic terminology, an artificial implant that replaces an ankle joint that is damaged.

Joint replacements are nearly always carried out because of pain that cannot be controlled by other methods such as painkillers, physiotherapy or other surgery. The most common cause of pain is osteoarthritis or inflammatory arthritis.

An ankle replacement procedure consists of replacing the worn out joint surfaces of the ankle with metal and plastic components shaped to allow continued movement of the ankle. There are several different types of ankle replacement available.

An ankle replacement involves replacing the bone at the lower end of the tibia (shin bone) and replacing the top of the talus (ankle bone).

There are two main types of ankle replacement. A fixed bearing (two part) or a mobile bearing (three part) implant. In either type the bones are covered by a metal component and then a plastic component is placed in between them. In a two-part implant, the plastic is fixed to the tibial component. In a three-part implant the plastic component moves freely between the metal parts. We do not yet know which type is better but in England the fixed bearing implant is now the most frequently used.

There are far fewer ankle replacements than hip or knee replacements because ankle arthritis is less common. Unlike hip or knee arthritis, most ankle arthritis is post traumatic. The commonest causes are following severe ankle fractures or recurrent severe ankle sprains. In addition the ankle sits upon a mobile foot which moves in multiple directions and the joint is also put under heavy weight load, often several times body weight. Ankle replacements are also newer technologies than hip or knee replacements. For these reasons ankle replacements have not yet achieved quite as good long-term results as hip or knee replacements.

The main implant components are described below:

The meniscal component is made of hard-wearing plastic (ultra-high molecular weight polyethylene) and sits between the talar and tibial parts. In a three-part ankle implant it moves forwards and backwards or twists slightly when the ankle moves (mobile bearing implant). In a two-part implant design, the plastic component is not mobile but instead is fixed to the tibial component (fixed bearing implant).

Ankle replacement implants must be aligned properly in order to work properly, and additional surgical procedures may be required at the same time as the replacement to help this to happen. For example, realignment surgery to ensure your heel is under your knee or soft tissue surgery to establish the right range of motion of the joint.

This covers the lower half of the ankle joint and the bone deep inside the ankle (talus). It is normally curved and fixed into place using pegs. Both of these components are made of metal and have a special coating to encourage the patient’s bone to grow into them.

The meniscal component is made of hard-wearing plastic (ultra-high molecular

weight polyethylene) and sits between the talar and tibial parts. In a three-part ankle implant it moves forwards and backwards or twists slightly when the ankle moves (mobile bearing implant). In a two-part implant design, the plastic component is not mobile but instead is fixed to the tibial component (fixed bearing implant).

on the outer side of the arm. Only part of the upper arm bone (humerus) and, if

required, the top of the outer forearm bone (radius) are replaced with a metal and plastic joint.

For all procedures, different sizes of components are available to aid the surgeon in finding the most suitable ‘fit’ for the patient.

Thinking about your treatment options

Joint replacement is a highly successful operation that can bring relief from pain and improve mobility. However, going through the process can be baffling and many patients do not always understand their options or the detail of their treatment plan. It is important you feel supported by your surgeon when discussing your available options.

Working together with your practitioner is known as shared decision-making.

Shared decision-making recognises all the different factors in your life that will lead to better quality decisions, from your own research, your surgeon’s advice, through to the support from your family and friends.

Sources such as this National Joint Registry information should make you feel confident in asking questions about your surgery, your implant and your recovery. There are some commonly-asked questions below. You may wish to write these out and make some notes.

Whatever the reason for your joint replacement, there are many others going through the same process, and it may help to know you are not alone. There is additional support out there for you on shared decision-making as well as advice on looking after yourself before and after surgery.

FAQs

As you make plans for your joint replacement surgery it may be helpful for you to make a note of any questions or queries you may have either for your surgeon or clinical team at the hospital. Some commonly asked questions are: 

  • Do I need joint replacement surgery? Are there other options available to me?
  • If I do, how should I prepare for surgery?
  • What type of implant are you recommending? What are the pros and cons?..
  • What surgical technique would be used? What are the pros and cons?
  • What should I know about my aftercare?
  • What do I need to think about when I return home after my operation?

Further information about ankle replacement

There are many organisations that provide additional general information about ankle joint replacement, including specific guidance before and after surgery as well as online discussion forums. Please see links here for some of these, such as: patient groups including Versus Arthritis; and the British Orthopaedic Foot and Ankle Society (BOFAS) who all have further useful advice.

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