Tarsal coalition is a congenital condition that occurs when the tarsal bones at the back of the foot are abnormally connected, causing pain and limitations in walking. Because of the joint bones, the foot may appear to be made up of a “bar of bones”, looking flatter and stiffer than a normal foot. Depending on the degree of attachment, if the bones are connected by fibrous tissue, the foot would be more flexible compared to a bony connection. About 1% of the population is affected by tarsal coalition.
Most cases are present at birth as the tarsal bones fail to separate during foetal development. And because tarsal coalition is an autosomal dominant genetic condition, children are likely to inherit the disorder if one of the parents has it.
The symptoms may only appear later in life or when the bones are beginning to mature. The most common sign is pain on the outside of the foot along the fibula, especially when walking or standing. The foot feels stiffer and flatter, and the patient might walk with a limp because of the rigid bone structure. Over time, other joints may be affected and pain is felt at the outer top side of the foot.
Because the bones are still developing during childhood, it may be difficult to diagnose until the bones begin to mature at about 9 years old. Some people only discover it during adulthood when affected by the symptoms. To help the doctor diagnose, it is important to give a full history of the duration and development of the symptoms, together with the activity level involved in the patient’s daily life. The patient’s walking movements are observed and followed by a thorough physical examination of the foot to look for tenderness and restriction of motions in the joints.
Depending on the severity of the condition, surgical or non-surgical treatment can be used to relieve the symptoms and reduce motion of the joints.
The foot is immobilized in a cast or brace for two to four weeks to allow the joints to rest. Steroid injections and oral medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) may be prescribed to reduce the pain and inflammation. After the cast is removed, custom made orthotics is placed into footwear to support the joints and reduce pain when walking. Patient may have to go through regular physical therapy sessions.
If the patient does not respond well to non-surgical treatment and the symptoms do not seem to subside, or if the condition is too severe, surgical treatment is opted for.
Depending on the age of the patient that tells the maturity of the bones, the goal of the surgery is either to restore the motion of the joints by removing or excising the bones, or fusing the joints together to form a solid bone. Removing or excising the bones is only recommended for young children as restoring motion in more mature and degenerative bones may not be enough to stop the pain.