Tarsal coalitions: A guide for patients

What is a tarsal coalition?

A tarsal coalition is when a bridge is created between two or more bones in the foot. Coalitions happen at the bones towards the back of the foot; around the heel area. They affect less than one per cent of the population, but can be on both feet in up to 50 per cent of patients. They affect men more than women (12:5) and they can also be found in first line relatives 38 per cent of the time.

What is the coalition made of?

The coalition can be made up of a number of different types of tissue, including bone, cartilage, fibrous or a mixture of these tissues.

Why does a coalition occur?

The main reason for the development of a coalition is the failure of the cells between the bones to differentiate/separate as a foetus.

What types of coalitions are there?

There are three main types of coalitions:

• Calcaneonavicular - 48 per cent
• Talocalcaneal - 44 per cent
• Talonavicular and calcaneocuboid - three per cent
• Other - five per cent.

Your podiatric surgeon will tell you what type of coalition you have.

The symptoms associated with the different types of coalitions happen at different times. These coalitions become more solid at different times.

• Calcaneonavicular,12 to 16-years-old
• Talocalcaneal, eight to 12-years-old
• Talonavicular and calcaneocuboid, three to five-years-old.

The age of coalition solidification influences when you start developing problems with the foot. However, many coalitions are not a problem for years, if at all. They often only become a problem after some type of trauma, for example spraining your ankle.

What are the most common problems associated with a coalition?

Most coalitions are non-problematic but when problems do occur, they are secondary to the rigid flatfoot that develops. A rigid flatfoot is when the foot stays flat when both weight and non-weight bearing. The lack of motion at the back of the foot can produce pain where the coalition is, as well as around the tendons on the inside aspect of the foot. Other problems can include arthritis; this is due to the lack of motion placing abnormal stress on to the joint and the associated bony overgrowth of arthritis.

Also, 20 to 30 per cent of patients can develop muscle spasms on the outside of the leg. The spasms occur in response to pain. The spasm further reduces the motion of the joint and so the pain, but in itself it can also become a problem.

The pain and lack of motion associated with a coalition can have a negative effect on your activities and quality of life.

What treatment options are available?

Treatment is either conservative or surgical.

The treatments outlined here are for the two most common coalitions: Calcaneonavicular and Talocalcaneal.

Conservative treatment

• Popliteal nerve block - if peroneal spasm is present. A popliteal nerve block is an injection behind the back of the knee that numbs the leg and reduces the spasm, allowing to see if the foot can be corrected for casting or insole therapy.
• Cast immobilisation – weight bearing below-knee cast for four to six weeks. This can help reduce the pain.
• Insoles - can help in splinting and supporting the foot.

Surgical treatment

Calacaneonavicular coalition

The most effective surgery for this type of coalition is removal. This has been proven to produce satisfactory results in many studies.

Following removal of the coalition, either a bone wax is applied to the bony surfaces or the muscle belly, which is present on the top of the foot, is placed into the gap. This sealing off significantly reduces the risk of the coalition redeveloping.

The procedure can be carried out under local anaesthetic. You will be in a below-knee cast for four to six weeks. After the operation, you will need to be seen by the physiotherapy department to help your rehabilitation.

Talocalcaneal coalitions

Surgery for talocalcaneal coalitions involves either:
• removal of the coalition
• fusion of the joints surrounding the coalition.

Removing the coalition is done when the coalition is not too big and when there is no arthritis affecting the surrounding joints.

A coalition greater than 50 per cent of the entire joint surface has been shown to produce poorer outcomes. However, some believe removal should be the first surgical option despite the size of the coalition.

Often, following removal of the coalition, the heel’s position needs to be addressed too. If the heel is still rolled out following the coalition’s removal, a procedure to reposition the heel by cutting the heel bone and moving it towards the inside of the foot is required. While the bone heals, the new position of the heel is held together by a screw.

All the studies mentioned previously were carried out on children under 16. The outcomes may vary in adults. If removal is chosen as the first surgical option and fails, this will not have an adverse effect on any future fusions. Fusion of the joints surrounding the coalition is suggested if a patient has arthritis. The type of fusion depends on the extent of the arthritis. For example, the number of joints affected. A fusion produces a rigid foot, but the degree of rigidity will depend on the number of joints that have been fused. Following a fusion, you will be placed in a non-weight bearing below knee cast for up to eight to 10 weeks.

Frequent or serious risks

All operations carry a small risk of complications. In foot surgery, complications are uncommon and most are resolved without permanent disability or pain. If you have any concerns, please discuss them with your specialist before deciding to have surgery.

• Infection (two in 100)
• Delayed healing of the skin (eight in 100)
• Prolonged swelling post operatively (four in 100)
• Thick or sensitive scar formation (four in 100)
• Blood clot deep vein thrombosis (DVT)
• No improvement – further surgery
• Non-compliance of patients (four in 100).

Complications following foot surgery are rare, but can happen. It is important to remember that if there is a complication, 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 only for cosmetic gains.