What Is A Tarsal Coalition?

In early development before birth, all the bone in the body is a mass of cartilage tissue. Then the individual bones start to develop inside that cartilage framework. At birth there is still a lot of the cartilage present, but the main bones are well on their way to being developed. They continue developing up until the mid to late teenage years when the growing bone has fully replaced all the cartilage framework. This is all quite normal and is how growth occurs.

While, this process can proceed quite normally, there are times when it does go wrong. In the foot, with its 26 small bones, the cartilage growth areas may not separate into individual bones and two bone may develop as one or a cartilage bridge may exists between two bones. This is technically referred to as a failure of differentiation. When this happens there will be no deformity or anything appearing wrong with the foot. Everything else develops normally and it usually does not interfere with the development of walking. As the bridge between the bones across where the joint should be is still the developing cartilage, some movement is possible. When problems start to develop is when the bone begins to develop and the two “bone” cannot move independently of each other. This may create some pain in that area or pain at other joints as the foot attempts to get the motion at other joints. This is called a tarsal coalition.

A tarsal coalition is a fusion between two bones in the rearfoot or a bridge of bone in the rearfoot. Any of the adjacent bones can be involved. The most common is a fusion between the talus and calcaneus bones (a talocalcaneal coalition). The next most common one is a fusion between the calcaneus and the navicular bones (a calcaneonavicular coalition). Both these start to become painful between about the ages of 5 to 10 as the bone develops and restricts movement and the child becomes more active. The pain is usually a vague ache in the joints around the area. The diagnosis is easily established with the use of an x-ray of CT scan.

The treatment of a tarsal coalition is usually with some sort of foot orthotic or support to restrict motion, as the pain comes from excessive motion of joints not involved in the coalition. The success of this often depends on the activity levels of the child. If that does not help a surgical removal of the boney bridge between the two bones is often successful.

By: Craig Payne

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Podiatry Arena has all the latest research and discussion on tarsal coalition including the talocalcaneal coalition and the calcaneonavicular coalition