What is tarsal coalition?
What is tarsal coalition?
This is an inborn (present at birth, as it occurred during fetal development) condition. It affects the bones of the foot in both children and adolescents. It is characterized by failure of the bones in the feet to separate during fetal development which can cause the foot to be painful, stiff and flat. About one percent of the population has a tarsal coalition, which means that this condition is not very common, but neither is it rare.
What part of the foot is affected by tarsal coalition?
This condition affects any of the tarsal bones. These are the seven bones that form the heel and the middle part of the foot. Two most common types of tarsal coalition are the calcaneonavicular coalition and the talocalcaneal coalition, where calcaneus, navicula and talus are Latin names of the affected tarsal bones. Name indicates which two bones did not separate. Sometimes, the term "bar" is used instead of "coalition" as it indicates that there is an unusual bar between the affected bones. The bar need not be fully formed, and it can be made of bone, cartilage, or fibrous tissue, which will affect the stiffness of the bar.
Why is this troublesome?
The foot is a highly complex structure. It is responsible for adequate contact with the ground; transfer of forces that enable us to walk, and for dampening of the impact that is natural in every kind of motion. If all this is to work as it should, all of the bones of the foot must move in an adequate relation to each other. Abnormality or lack of motion between any two bones of the foot affects the entire foot and leads to increased stress in other joints in the foot, which will increase wear and tear in them and lead to pain.
Symptoms and diagnosis
The primary symptom caused is pain, which is typically felt on the outside of the foot, below that large bony protrusion on the outside of the ankle. Advanced condition affects other joints and in such cases pain may be felt on the top of the foot and on the outside of the foot. Diagnosis is determined by history and physical examination. Areas of tenderness and restriction of motion in each of the joints in the foot will be observed in particular. An X-ray exam is very helpful for overview of the situation in the foot, but the CT scan is regarded as the best tool. MRI scan is used if the coalition is made of soft tissue.
Surgery and recovery
Surgery is used to remove or excise the bar and to restore normal motion between the two bones as much as possible, or to fuse the affected joints together solidly. Excision works better for younger children, whereas a fusion may be necessary in adolescents and older children.
Recovery after the excision procedure is quicker as there is no bone to heal together, and any kind of activity, if not painful, is allowed soon after the surgery. On the other hand, the bones will need to heal together and fuse after the fusion procedure. Screws or metal pins are commonly used to hold the bones together until they heal, and use of a cast or brace is recommended. Weight bearing may be delayed up to six or eight weeks..