Ankle replacement FAQ: Everything patients need to know

An ankle replacement can offer life-changing mobility and pain relief to those suffering from arthritis of the ankle. In his latest online article, esteemed consultant orthopaedic surgeon Mr Adam Ajis offers his expert insight into this procedure, explaining the different types of ankle replacement available and who is a suitable candidate.

Am I a good candidate for ankle replacement surgery?

I am often asked what makes a good candidate for ankle replacement surgery. Ankle replacements work best in people who are over 60 years of age, and diagnosed with end-stage ankle arthritis. The symptoms of this are typically pain, which is worse during activity and when weight-bearing in the affected ankle. This is often accompanied by swelling and stiffness. There may be a crunching or grinding sensation in the ankle on mobilising.

We will often take weight-bearing x-rays of the ankle to determine the extent of the ankle arthritis and to determine the alignment of the ankle joint itself. Sometimes the ankle joint can wear out unevenly, and one side can appear more worn out than the other. This causes the ankle to become tilted. If the tilt becomes too severe, an ankle replacement may no longer be a good option.

If the arthritis or wearing out is limited to the ankle joint, an ankle replacement can give the best results here. Often there is lesser arthritis in the surrounding joints, which can sometimes give residual pain even after an ankle replacement. Typically, this is not as severe. The quality of bone has to be good and there should not be too many/very large cysts in the bone. However, with more modern ankle replacements and newer techniques, even these difficulties can be overcome.

What are the different types of ankle replacements available, and which one is best for me?

There are various different types of ankle replacements available. Some have been around longer than others. Generally speaking, these can be divided into two broad categories. These are fixed bearing or mobile bearing ankle replacement.

With a mobile bearing ankle replacement, the high molecular weight polyethylene component is designed to move between the upper and lower metal alloy components. The advantages of this group of ankle replacements, is that it can be more forgiving in terms of component positioning and it is easier to revise if needed. The disadvantages are that there can be more microscopic polyethylene wear particles generated as there is friction on both sides of the polyethylene component. These small particles can cause osteolysis or cyst formation in the surrounding bone.

The other group of ankle replacements are known as fixed bearing ankle replacements. In this type of ankle, the polyethylene component is vigorously fixed in place to the tibial or upper component. This means that the talar or lower component will slide upwards and downwards along a predefined track or grooves incorporated into the polyethylene. The advantage of this type of ankle replacement is there is only one surface for polyethylene wear to be generated from. However, it requires a more precise and exact approach for implantation and has to be put in at exactly the right angle and position to get the best out of it. It is less forgiving for small areas of malalignment.

The latest generation of ankle replacement, involves patient specific implementation. With this type of ankle replacement, a more precise biomechanical alignment can be achieved. A CT scan is taken of the lower leg, which is then converted into a three-dimensional model of the bony anatomy. This is then uploaded to a computer software programme, which allows you to determine optimal implant size, alignment and position in all three dimensions.

Complex deformities can be accounted for and corrected accordingly. Potential hazards and pitfalls can be pre-empted, such as pre-existing metal work from previous fractures, which might get in the way, or large cysts in the bone which might compromise longevity. These can then be planned for and accommodated for during the surgery. This is my preferred option for all patients and is something I am particularly passionate about.

What are the typical risks and complications associated with ankle replacement surgery?

Ankle replacement surgery is on the whole very safe and predictable. Like with all surgery however, unexpected complications can arise such as infection, which can often be cleared up with antibiotic tablets or in the rarer case of deep infection, may require multiple surgeries to clear and having the new ankle removed.

Numbness over the top of the foot caused by division or stretching of the nerves can sometimes occur as part of the surgical approach to the ankle joint. Fractures can occur intra-operatively or post-operatively during the healing process.

Blood clots in the legs, which can travel to the heart and lungs is also a rare complication. However, steps are taken to mitigate this. Sometimes the tendons behind the ankle joint can get damaged if they are very stuck down.

In the longer term, the ankle joint can wear out if excessive demands are placed on it. Osteolysis or cysts in the bone can develop in a small minority of patients. Revision surgery to replace the ankle joint can sometimes be necessary.

What is the recovery process like after ankle replacement surgery?

Ankle replacement surgery typically involves a 1-night hospital stay. Occasionally, patients can be discharged home the same day. The first few weeks are typically spent in a plaster cast without being able to put weight on the operated leg. Elevating the leg is extremely important in these first two weeks, to keep swelling under control and to help the incision to heal.

Slow incision healing can be a complication due to poor blood supply, supplying the skin at the front of the ankle joint. Once the skin incision has healed, typically in a boot to offer some protection. The boot is worn for up to 4 weeks and physiotherapy can commence in the interim period. Pain relief from arthritis is very vast and a full return to normal function can be expected in the coming months.

What are the long-term outcomes of ankle replacement surgery?

The earlier ankle replacements didn’t do so well and many have been taken off the market so are no longer in use. The more modern ones appear to have a much better track record. Generally speaking, around 8/10 ankle replacements are still doing well 10 years into their lifespan. As time progresses, more data will be collected for longer term results. We expect the latest generation of ankle replacements to do better.

Mr Adam Ajis is a distinguished consultant orthopaedic surgeon based in West Sussex & Brighton, with over 20 years of experience. If you would like to book a consultation with Mr Ajis, you can do so today via his Top Doctors profile.