The tarsus is a group of bones located in the mid and hind foot that comprise the ankle and heel. A tarsal coalition is a developmental condition where two or more of a foot’s tarsal bones fuse together. Tarsal coalitions can occur across the joint between talus and calcaneus (talocalcaneal coalition) or between the calcaneus and navicular bones (calcaneonavicular coalition).
A tarsal coalition most often occur as a result of an inherited disorder where the cells of the tarsal bones fail to differentiate during a fetus’ development in the womb. Tarsal coalitions may also be caused by an infection, injury, or advanced arthritis.
Children typically do not develop symptoms until age 8 to 16 years. While symptoms vary, the most common are:
- Pain on the top of the foot
- Flat feet
- Muscle spasms
- Rigidity or stiffness in the affected foot
To diagnose a tarsal coalition, a medical history is taken followed by a physical examination and x-rays. Additional diagnostic tests such as MRI and CT scans are done to rule out other conditions and confirm the diagnosis.
The objective of non-surgical treatment for a tarsal coalition is to relieve pain and muscle spasms. Anti-inflammatory medications, cortisone injections, or anesthetic injections can provide temporary pain relief. Custom orthotics such as shoe inserts may be recommended to support the affected joint.
Surgery may be recommended if pain persists even after non-surgical treatment. If there is no arthritis, the union between the bones may be removed to allow for a normal range of motion. In some cases, the bones of the affected joints may be completely fused to limit range of motion and reduce pain. After surgery, the foot is immobilized with a splint or cast and crutches are used to prevent the foot from bearing weight as it heals. The child may be instructed to perform specific foot exercises to restore normal muscle tone and range of motion.