Each joint in the foot serves a specific purpose to rotate and move the bones in relationship to one another for walking. Any lack of proper movement of the joints could lead to deformity and pain. Some people are born with a genetic joining of 2 foot bones that are normally separated from each other. This is called a collation. Coalitions of the foot are usually in the area called the rear-foot called the tarsus.
The two main Tarsal Coalitions are:
- Calcaneonavicular Colation: Between the heel bone and the inside arch bone. Often called a CN Bar.
- Talocalcaneal Coalition: Between the ankle bone and the heel bone. Often called a Subtalar Coalition.
Diagnosis is made by a thorough foot examination and gait analysis. Specialized x-rays and in office CT Scans are need to evaluate the structure of the bones and the relationship between them.
A coalition is present at birth, but the joining between the bones is soft tissue and the bones are able to move more freely, so most babies and children do not have pain. During development, the soft tissue joining between the bones will promote flattening of the arch. The soft tissue then becomes bone during growth. Once it has developed into bone, the foot can become painful at any time. Pain is usually triggered by a simple or sever foot sprain from an injury or sports. The arch will continue to flatten and can become a rigid flatfoot.
Over time painful arthritis can develop at the joints due to their abnormal movements causing cartilage and joint damage.
Early treatment will include, rest, use of a walking boot after injury, and physical therapy and use of anti-inflammatories. Custom molded orthotics can help to support the flattening arch and fatigue. Cortisone injections can help to reduce the inflammation and pain at the site.
In many cases, surgery is warranted to reduce or remove the coalition. Early surgical treatment can reduce the chance of arthritis and the need for joint fusions.