Tarsal Coalition

Written By: Chloe Wilson BSc(Hons) Physiotherapy
Reviewed By: FPE Medical Review Board

Tarsal Coalition is a problem in the foot where two bones are joined by an abnormal connection or bridge.

It causes pain and stiffness in the foot, typically starting during adolescence.

It is typically a congenital problem i.e. something you are born but can be caused by a foot injury or infection.

Tarsal Coalition is one of the rarer causes of side of foot pain affecting approximately 1 in every 100 people. One or both feet may be affected.

Symptoms of tarsal coalition often come on very suddenly resulting in side foot pain, fatigue and foot cramps often causing people to walk abnormally. It can cause other foot problems such as ankle sprains and abnormal foot biomechanics.  Tarsal coalition treatment usually consists of surgery, shoe inserts or casting to immobilise the foot.

What Is Tarsal Coalition?

The bones at the back of the foot are known as the tarsal bones, made up of the talus, calcaneus, cuboid, navicular and cunieform bones. 

Tarsal coalition is a condition where two of the tarsal bones become become attached to each other by abnormal growth of either:

• Bone: Osseus Coalition (synostosis)
• Cartilage: Cartilagenous Coalition (synchondrosis)
• Fibrous Tissues: Fibrous Coalition (syndesmosis)

This abnormal growth forms a "bridge" or "bar" between the two bones. The extent of the join varies from mild to extensive.

The most common types of tarsal coalition are:

• Calcaneonavicular Coalition: between the calcaneus (heel bone) and the navicular aka CN bar
  
• Talocalcaneal Coalition: between the calcaneus and the talus aka TC bar

These account for over 80% of cases of tarsal coalition but bridges can form between other tarsal bones.

Tarsal coalition restricts the normal movement between the two bones resulting in stiffness and immobility in the hind/mid foot region. This in time impacts on the surrounding joints and can lead to degenerative arthritis.

What Causes Tarsal Coalition?

There are a number of things that can cause tarsal coalition:

• Genetic Abnormality
• Foot Trauma
• Infection
• Arthritis

Most cases of tarsal coalition are congenital due to a genetic mutation which affects how the individual tarsal bones develop.

A process called mesenchymal segmentation fails to happen properly so rather than developing as separate structures, two or three of the tarsal bones become connected.

There is thought to be a genetic link with tarsal coalition.

Tarsal Coalition Symptoms

Typical symptoms of tarsal coalition include:

• Foot & Ankle Stiffness: and rigidity in the back of the foot, known as the hindfoot
• Foot Pain: below the ankle and at the back of the foot, worse when weightbearing or with activity e.g. standing, walking, running
• Flat Foot Arches: reduced height of foot arches in one or both feet
• Muscle Spasms: increased spasticity in the peroneal muscles causing calf pain
• Limping: when walking, particularly long distances
  
  

Symptoms of tarsal coalition don't usually appear until a child reaches around 10 years of age as that is when their bones start to mature.

Up until this point, much of the foot structure is cartilage which gradually changes and hardens, through a process called ossification, to bone. If a coalition structure is present, it ossifies too.

This ossification happens at different ages depending on which bones are involved:

• Calcaneonavicular Coalition: typcially ages 8-12 years
• Talocalcaneal Coalition: typically ages 12-15 years

Prior to ossification, people don't usually develop any symptoms of tarsal coalition. But once the area starts to harden it may start to cause problems.

Only around one quarter of people who have tarsal coalition will get symptoms from it, in most cases it goes completely unnoticed. Many only experience symptoms in adulthood or if they develop secondary conditions such as arthritis or suffer from a foot injury.

How Is Tarsal Coalition Treated?

Tarsal coalition only requires treatment if it is causing symptoms, otherwise it is best left alone. Many symptomatic cases can be treated non-operatively but in just over 50%, surgery may be required.

Non-Operative Treatment

Non-operative treatment for tarsal coalition includes:

• Rest: Avoiding aggravating activities for 4-6 weeks reduces the stress on the tarsal bones and can reduce pain
  
  
• Shoe Inserts: Orthotics e.g. heel wedges or arch supports can be used to correct abnormal foot position, stabilize the foot and reduce the forces going through the affected joint
  
  
• Temporary Immobilization: with a below knee cast/boot and crutches for 6 weeks to take the weight and stress off the tarsal bones - abolishes symptoms in around 30% of people
  
  
• Injections: A mixture of anesthetic and steroid can be injected into the area to reduce pain, inflammation and spasming
  
  
• Medications: Non-steroidal anti-inflammatories such as ibuprofen can help to reduce the pain and inflammation associated with tarsal coalition
  
  
• Physical Therapy: gentle range of motion exercises, calf stretches, massage and ultrasound

These treatments help to reduce the symptoms of tarsal coalition but do not correct the deformity.

Tarsal Coalition Surgery

Tarsal coalition surgery is indicated if:

• Symptoms have failed to settle with non-operative treatment
• Coalition involves more than 50% of the joint surface

Surgery will depend on the location and severity of the tarsal coalition, the condition of the surrounding joints and the age and activity level of the person. The two options are:

• Resection: Removal of the coalition to restore normal movement. The coalition bridge is surgically removed and replaced with muscle or tendon and fatty tissue.For calcaneonavicular coalition they use part of the extensor digitorum brevis muscle and for talocalcaneal coalition they use part of the flexor hallucis longus tendon.  Foot deformities can also be corrected at the same time.
  
  
• Arthrodesis: The affected joint is fused so the bones are held in the correct position by screws, pins or a screw-and-plate system. This prevents any movement at the joint and is typically done for larger coalitions or when there are associated degenerative changes.

Following each type of tarsal coalition surgery, you are normally given a cast or boot to immobilise the foot, and crutches as you will not be allowed to take weight through the foot for a few weeks while it heals. After this, you will start physical therapy in order to regain mobility and strength in your foot.

It can take 6-12 months to fully recovery from tarsal coalition surgery, but surgery is successful in around 85% of cases.

Summary

Tarsal coalition is a congenital foot problem that can cause pain and stiffness in the foot due to a bridge forming between two tarsal bones. It is present in around 1% of the population but does not always cause any problems.

Treatment usually involves a combination of rest, orthotics, injections and medications but the more severe cases may require tarsal coalition surgery.

Most people make a good recovery with the correct treatment.

Tarsal coalition is just one possible cause of foot pain - for help working out what is wrong visit the foot pain diagnosis section.

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Page Last Updated: 11/03/21
Next Review Due: 11/03/23

References

1. Joints Journal: Talonavicular Coalition as a Cause of Foot Pain. By A. Macera, F. Teodonno, C. Carulli, A. Borrego and M. Innocenti

2. Science Direct: Tarsal Coalition. By M.Myerson MD & A. Kadakia MD. 2019

3. Resection of Tarsal Coalition. Southampton Children's Hospital. March 2019