A guide for patients: Accessory navicular operation

An accessory navicular can affect up to 10 per cent of the population.

For some people, it does not cause any problems but for others it can cause pain around the inside of the arch and is often associated with a bony prominence. These problems are related to a small accessory bone, the accessory navicular. In cases where the accessory navicular causes pain it sits between one of the main tendons of the foot, the tibialis posterior tendon and the bone that the tendon is meant to insert into - the navicular. Pain occurs when the tendon contracts, which produces movement between the accessory navicular and the navicular. In some cases, osteoarthritic changes can develop between the two bones.

The tibialis posterior tendon is an important tendon of the foot and ankle and helps to maintain the foot’s position. In some cases, the patient may notice a reduction in the height of their arch.

Why does the pain suddenly occur?

The accessory bone has been present since birth, however once bones begin to fully harden, around puberty, they become less accommodating to movement. In some cases, pain does not happen until adulthood, perhaps after an injury, such as a trip or fall.

What can be done?

Sometimes, it is possible to relieve the pain by using an insole. This helps by supporting the foot and reducing the amount of work that the tendon needs to do, which reduces movement between the two bones. Wearing a trainer can also help as this provides more support to the foot. Unfortunately, not all cases respond to this care.

Surgical management

Surgery aims to improve your activities of daily living and quality of life by reducing discomfort around the arch area of your foot and to make fitting footwear easier by removing the bump on the side of your foot.

Surgery involves making an incision over the affected area to expose the accessory bone. The tendon that is attached to the accessory bone is released and the accessory bone removed. The tendon is then re-attached to the normal bone through a suture anchor; a small screw and stitch thread.

Following the procedure, you will be placed in a non-weight-bearing below knee cast for about six to eight weeks.

About day case surgery under local anaesthetic

Surgery is carried out under local anaesthetic as a day case. This means that you are awake during the operation but a screen will prevent you from seeing the surgery.

To numb your foot, you will either be given some injections around your ankle or behind the back of the knee. You can eat and drink on the day of surgery; there is no need for fasting.

The operation may take up to one hour but you should be ready to be at the hospital longer than this to allow for preparation and to give you the opportunity to rest after surgery. Throughout the operation, you will usually have a tight band, called a tourniquet, around the ankle to keep blood away from your foot. This is sometimes uncomfortable but is immediately released after the operation.

If you decide on surgical management, you will be invited back to attend a pre-surgical clinic. A member of the nursing team will take a medical history. If you are on any medication, please bring a list with you. This is a good opportunity to ask questions and discuss any concerns you may have about the procedure.

You must have a competent adult at home for the first day and night after surgery.

Recovery after your operation

Following this procedure, you will be in a non-weight bearing cast for up to eight weeks.

The first two days

• You will be in a plaster of Paris below knee cast. This cast is rather heavy but allows for swelling of your foot. This cast will be on for about two weeks.
• You should not walk on the foot which had surgery.
• You must rest with your feet up, as much as possible. You should restrict walking to bathroom visits. When getting about, you must use crutches. The nursing team will show you how to use your crutches and provide you with written information.
• You should take the prescribed painkillers. If you experience pain, it is usually worse for the first two days.
• If you are still experiencing pain after three to four days that is not relieved by the painkillers, you should contact the department.
• If you have any concerns over your foot you should contact the department.
• The department is closed at the weekend. If you need to call out-of-hours, please contact your GP and go to your local A&E department.

Two weeks after surgery

• The cast will be removed and is replaced with a lightweight fibreglass cast, which stays on for a further six weeks. You must continue not to bear weight on the foot and use crutches.

Eight weeks after surgery

• At eight weeks, the cast will be removed and you will be able to begin partial weight-bearing with your crutches and a rigid soled trainer.
• No high-impact activities are allowed.
• Your foot will swell and become uncomfortable, especially if you overdo it.
• You will still need to rest and keep the leg elevated.
• Once you begin to bear weight on the foot, the operation site will become painful and may swell. This is normal and you should not be concerned. However, if you are experiencing pain that is not alleviated by rest or pain killers you need to contact the department.
• Physical therapy exercises will be given to you by the podiatric surgeon.

10 weeks after surgery

• You can begin to fully weight-bear on the foot and can gently start to return to normal activities. You should still avoid high-impact activities and remain in your running trainer.
• Be aware that you should not walk on uneven ground, especially if it is going to make your foot roll out.
• You can now return to driving; however, you must feel able to perform an emergency stop without hesitation or pain. Check with your insurance company about your cover.
• You may return to work but this is dependent on the type of work and footwear necessary for your job. For certain jobs, returning to work in less than 12 weeks can be an unrealistic expectation.

Four months after surgery

• Although the foot should now be comfortable and returning to normal, there will still be noticeable swelling, particularly towards the end of the day. This is normal.
• You may need to stay in your running trainer for another six weeks.
• If the healing process is progressing well, you could start to look at returning to sporting activities. When returning to sports, please start slowly and be aware of the position of your foot.

Six months after surgery

• Residual swelling should now be slight, although the healing process continues for 12 months
• You should be getting the full benefit of the surgery.

12 months after surgery

• All healing is now complete, swelling should be completely resolved.

Frequent or serious risks

All operations carry a small risk of complications. In foot surgery, complications are uncommon and most resolve without permanent disability or pain.

General and specific complications of this procedure include:

• infection (two in 100)
• delayed healing of the skin (eight in 100)
• non-compliance of patients (four in 100)
• prolonged swelling post operatively (four in 100)
• thick or sensitive scar formation (four in 100)
• tendon avulsion – coming away from the bone
• blood clot - deep vein thrombosis (DVT)

About 20 per cent of patients can still experience pain in the arch of the foot following surgery. If this happens, the use of an insole and steroid injections can help settle the pain.

If the tendon does not fully heal to the bone, you may experience a slightly weaker foot and a decrease in the height of the arch. This can be treated with insoles but, in some cases, further surgery may be required.

Complications following foot surgery are rare but can happen. If a complication arises, you will need to visit the hospital more frequently and there could be a significant impact on your recovery and return to work time. Foot surgery should be avoided if it is for cosmetic gain only.