The tarsal bones are a set of seven bones that make up the heel and the lower ankle area of the foot. Tarsal coalition describes a birth condition where two or more bones in that area are connected abnormally. While this occurs at birth, it usually is not diagnosed until late childhood or early adolescence, when tarsal coalition may begin to cause limited motion, stiffness, pain, or frequent ankle sprains. An x-ray is required to diagnose this condition and some go undiscovered throughout life.
Coalitions can be a connection of bone, bone and cartilage, or fibrous tissue. The two most common tarsal coalitions are between the heel bone to the foot bones or the heel bone to the ankle bones. If symptoms are not severe, then rest and immobilization will alleviate problems. Next steps include orthotics, steroid injections, and finally, surgery to remove or separate the coalition and insert muscle or fat to keep it separated.