#treatment - Foot & Ankle

Ankle Fusion (Arthrodesis)

When ankle arthritis reaches end stage levels an ankle fusion may become necessary. Most surgeons in the U.K. now perform this through keyhole techniques. Occasionally an open technique may be indicated, for example in cases where there is gross deformity or if previous plates and screws have been used and need to be removed. 

Ankle fusion is a reliable operation with good results in eliminating pain from arthritis. 

What are my alternatives?

Non surgical options include injections and braces which can be effective in the early stages of arthritis.

By the time an ankle fusion is indicated the so called ‘joint preserving’ options such as injections or keyhole clean up surgery will probably have been tried and would not be indicated.

The main alternative to an ankle fusion therefore is a total ankle replacement. You can find further information on Ankle replacement surgery on this website.

On occasions bone realignment surgery may also be indicated. This may be the case if there is significant mal-alignment and the ankle joint is preserved.  You should discuss your individual options with your surgeon before deciding on which operation you should have. 

What is an ankle fusion?

An ankle fusion is a recognised and reliable surgical treatment for symptomatic ankle arthritis. The aim is to “freeze” the ankle so no movement remains and in doing so relive the pain from the arthritis.

In an arthroscopic ankle fusion a keyhole approach is made to the front of the ankle and the joint surfaces are prepared for fusion. This means that any bone spurs are shaved away, the remaining cartilage covering the joint is cleared down to the underlying bone which is then breached so that bleeding surfaces are reached. When this process is complete screws are put across the joint through separate small 5-10 mm incisions on the inside of the lower leg whilst ensuring that the foot is in a flat 90 degree position. 

X-ray of an ankle fusion using the described technique

The operations usually takes around 90 mins and you will have four or five small (5-10mm) incisions which are closed with absorbable sutures. A below the knee half plaster is then used.

What are the risks of this surgery?

Infection

 A small risk of infection exist at a rate of around 1 %. This is higher in diabetics or those who smoke. Some cases can be treated with antibiotics alone. More severe cases may need surgery to remove the screws and perform a clear out. Often multiple operation may be needed to eradicate the infection and the fusion operations may have to be repeated occasionally using external fixation frames and plastic surgery to achieve skin cover. Extremely rare cases may end in a below the knee amputation. 

Bleeding

 Excessive bleeding may lead to formation of congealed blood under the skin (Haematoma) this may need surgery to evacuate in rare cases. 

Nerve injury or Numbness

Sensory nerves to the foot cross the ankle. Whilst care is taken to avoid injury occasionally they can be bruised or cut. This will not affect walking ability but may cause a patch of numbness on the back or outside of the foot. Sometimes a small regrowth of the nerve may lead to a painful nodule in the scar (neuroma), this may need to be surgically excised. 

Blood vessel injury 

One of the blood vessels that supply the foot runs in front of the ankle and is at risk of injury. The rate is less than 1%. 

Thrombosis 

Blood clots in the calf (Deep vein Thrombosis) can occur after lower limb surgery. These can break off and go to the lungs causing pulmonary embolism (PE). We assess individual risks of thrombosis and balance against the side effects of blood thinning injections. You are likely to be offered these injections for the time you are in plaster. Usually for around six weeks. 

Complex Regional Pain Syndrome (CRPS)

This is a rare complication that can result in post operative pain and skin colour changes in the whole of the foot and sometimes the entire lower leg. It occurs in less than 0.5% but can result in a poor outcome and prolonged recovery. 

Non Union 

This is when the fusion fails to happen and the ankle joint will have motion which can remain painful and may result in the screws breaking. If this happens then you may need the procedure repeated to ensure a solid fusion occurs. You may find that bone graft is used or an open approach adopted in the repeat of the operation. 

Mal-Union

Occasionally the foot is placed in a sub-optimal position. The aim is to fuse the ankle in a position that results in the foot being square to the ground. If this isn’t achieved then you may find it difficult to walk. In most mild deformity a shoe insert is likely to solve the problem. More severe cases may need repeat surgery. 

Longer-term Arthritis in other foot joints

In the long-term, stress placed on the surrounding joints may lead to wear and tear and arthritis in those joints as they will be working harder to compensate for a stiff ankle. This may lead to pain in those joints. This occurs after 10 or 15 years and if severe may need further surgical treatment.

How stiff will my ankle be? What can I do?

This is the question most people will ask. By the time the ankle needs fusing a significant amount of up and down motion has been lost from your ankle. Any remaining motion is painful.

There are many other joints in your foot that can compensate and take on the up and down motion. In fact, most day to day activity can be performed with a fused ankle, including higher impact exercises such as jumping or running although sprinting may be difficult.

Most patients will walk without an an obvious limp and will be able to drive.

Any task that requires you to maximally bend the ankle may need to be adapted. One such task is going down stairs.

This article in the daily mail demonstrates how active individuals are following this surgery.

Below is a patient with a fused ankle who has been asked to move his ankle up and then down. The movement is generated from the neighboring joints and demonstrate the range of movement that is still available after an ankle fusion.

 

Ankle in the 'up' or maximal dorsi-flexion position

Ankle in the ‘up’ or maximal dorsi-flexion position

 

Ankle in the 'down' or maximal plantar-flexion position

Ankle in the ‘down’ or maximal plantar-flexion position

What happens after surgery?

Weeks 0-2

In this time you will be in the post operative plaster back-slab. You must not weight-bear on the operated leg. Take time to elevate and control the swelling and take the prescribed painkillers one the local aneasthetic block has worn off (usually by around 24 hours post op). 

You should also try and get around in crutches regularly to make sure the rest of your bones and joints don’t become weak and wasted. It will also help blood flowing around and reduces the risk of thrombosis. 

At the end of this period you will have an appointment to see your surgeon who will change the cast to a full plaster and inspects the wounds. 

Weeks 2-6

Following your 2 week appointment you will remain non-weight-bearing on your crutches for a further 4 weeks. 

You must continue with regular elevation and control the swelling. The pain should be more tolerable by now and you may need fewer painkillers. 

Weeks 6-12 

You will attend for a check X-ray at the 6 week mark and at this stage if good healing is seen you will be taken out of the cast. Occasionally you may be taken out completely into your normal footwear but often a walking boot is provided to help you transition. 

Weeks 12 plus

At this stage an X-ray is repeated and full healing should be demonstrated. You will be in your normal footwear and getting back to normal day to day activity perhaps with a physiotherapist helping you. Return to higher impact activities is normally possible from around 6 months post op.

Swelling may persist for up to 12 months from the operation.

 

Further information

Below you can find links to recommended further information on the internet.

Patient information leaflet provided by Guy’s and St. Thomas’ NHS Trust.

Information provided by the American Foot and Ankle Society