Tarsal coalition is a bone condition that causes decreased motion or absence of motion in one or more of the joints in the foot. The bones found at the top of the arch, the heel, and the ankle are referred to as thetarsal bones. A tarsal coalition is an abnormal connection between two of the tarsal bones in the back of the foot or the arch. This abnormal connection between two bones is most commonly an inherited trait.
The lack of motion or absence of motion experienced in a tarsal coalition is caused by abnormal bone, cartilage, or fibrous tissue growth across a joint. When excess bone has grown across a joint, it may result in restricted or a complete lack of motion in that joint. Cartilage or fibrous tissue growth can restrict motion of the affected joint to varying degrees, causing pain in the affected joint and/or in surrounding joints.
Symptoms usually include an aching sensation deep in the foot near the ankle or arch, accompanied by muscle spasms on the outside of the affected leg. Nonsurgical treatments, such as corrective shoes or custom orthotics, physical therapy, injections, and anti-inflammatory medications, are the first courses of action. Surgery is sometimes performed in severe cases to allow for more normal motion between the bones or to fuse the affected joint or surrounding joints.