Subtalar Fusion

What is a Subtalar Fusion ?

The subtalar joint is below the ankle joint and allows side-to-side and tilting movements of the heel. This operation removes the arthritic joint and fixes the residual bones together with metal screws through the heel, such that new bone will grow across the gap and 'fuse' the joint . The surgery is performed through a 5-8 cm incision along the outer side of the ankle. The operation takes approximately 1.5 hours. The joint will then be permanently rigid and no longer painful. There will be no change in the up/down ankle movement, and walking will not be altered on flat ground; however on uneven surfaces the ankle will feel a little 'inflexible', and you may benefit from orthotics.

What happens after surgery ?      

After surgery, your leg will be immobilised in a backslab plaster cast for 2 weeks. You will remain in hospital at least 1 night. The foot must be elevated (above the level of the pelvis) for 90% of the time for the first 10 days. This helps to reduce swelling and the risk of infection, and helps wound healing.  Naturally, short periods of walking/standing are allowed but no weight must be taken through the operated leg for 6 weeks. After 2 weeks the backslab will be removed and the stitches taken out.   Another non-weightbearing plaster is applied for a further 4 weeks.  At 6 weeks if all is well then no more plastercasts are needed and you can walk freely. If the fusion has not completely healed, then a further 6 weeks in a weightbearing cast is necessary. Usually no physiotherapy is required.  

What are the risks of surgery ?

Stiffness & swelling
Initially the foot/ankle will be very swollen and need elevating. The swelling will disperse over weeks/months but may still be apparent at 9-12 months.

Infection
There is always a risk of infection with surgery. Smoking increases this 16-fold, and rheumatoid arthritis over 8 times. You will be given 1 dose of intravenous antibiotics during surgery, and 2 doses after surgery. The best way to reduce the chance of acquiring an infection is to keep the foot elevated for 10 days. If there is an infection it may resolve with a course of antibiotics but often results in failure of the fusion.

Malposition
Ideally, the ankle is fused in a position that allows optimum function and gives the best appearance.  I take great efforts to judge the best position for the fusion at surgery, but as you are asleep and lying down, it is not always possible to achieve this 'best' position.  If the position is not optimal following surgery, most deformities can be accommodated by insoles and footwear. Rarely is further surgery required.

Non Union.
This is when the joint fails to fuse and bone has not grown across the joint. It can take 6-12 months before we know if this is the case. The risk of this is approximately 5-10%.   Smoking increases this risk 4 times. If a non union does occur and is painful, then further surgery is usually needed.  

Nerve Damage.
Several nerves lie alongside the incision - the superficial peroneal and sural nerves.  They supply sensation to the side and the top of the foot and toes.  They may become damaged during the surgery and this will leave a patch of numbness, either at the side of the foot or over the top of the foot and toes.  The numbness may be temporary or permanent.  There is approximately a 10% of this happening.

How long will i be off work ?

4 weeks off work is required for sedentary posts
10 weeks for standing or walking posts, 12 weeks for manual / labour intensive posts
A sick note will usually be provided for the first 2 weeks, further notes can be obtained from the GP.

What is the usual postoperative follow up ?

2 weeks for removal of sutures and change of plaster
6 weeks for removal of cast and Ankle Xrays.
3 months Ankle Xrays.