Tarsal coalition is an abnormal connection of two or more bones in the foot. The bones affected — called tarsal bones — are located toward the back of the foot and in the heel, and the connection of the bones can result in a severe, rigid flatfoot.Although tarsal coalition is often present at birth, children typically do not show signs of the disorder until early adolescence. The foot may become stiff and painful, and everyday physical activities are often difficult.
A tarsal coalition occurs when two bones grow into one another, connected by a bridge of bone, cartilage, or strong, fibrous tissue. These bridges are often referred to as “bars” and they can cover just a small amount of the joint space between the bones, or a large portion of the space.
The two most common sites of tarsal coalition are between the calcaneus and navicular bones, or between the talus and calcaneus bones. However, other joints can also be affected.
In most people, the condition begins before birth. Although the coalition forms before birth, its presence is often not discovered until late childhood or adolescence.This is because babies’ feet contain a higher percentage of soft, growing cartilage. As a child grows, this cartilage mineralizes (ossifies), resulting in hard, mature bone. If a coalition exists, it may harden, too, and fuse the growing bones together with a solid bridge of bone or fibrous tissue similar to a scar. As a result, the hindfoot stiffens, causing pain and other symptoms. The stiffness and stress that tarsal coalitions produce may lead to arthritis over time.
Many tarsal coalitions are never discovered because they do not cause symptoms or any obvious foot deformity. When symptoms do occur, they may include:
To accurately diagnose the number, location and extent of the coalition(s), we will need images of your foot and ankle.
When nonsurgical treatments are not effective at easing pain or improving function, surgery is recommended. The surgical procedure will depend on the size and location of the coalition, as well as whether the joints between the bones show signs of arthritis.