Tarsal coalition develops between the tarsal bones found in the back of the foot due to an abnormal connection between two of the tarsal bones. Tarsal bones include the heel bone, the talus and navicular bones above the heel bone, the cuboid in front of the heel bone, and the cuneiform bones that sit in front of the navicular bone and on top of the cuboid bone. Tarsal coalition can occur in one or both feet, resulting in pain and limited mobility. It most commonly results from bone malformation in-utero, but it does not usually cause problems for the affected individual until late childhood or the teenage years. It can also stem from infection, injury, or joint problems such as arthritis.

Symptoms include stiffness, pain, muscle spasms, and fatigue in the legs. Flatfoot can also arise from tarsal coalition. Treatments include orthotics, immobilization, anti-inflammatory medication (ask a doctor before taking any medication), cortisone and/ or anesthetic injections, physical therapy, and surgery if the above treatments are unsuccessful in alleviating pain and other symptoms.