A tarsal coalition is an abnormal connection between two bones in the midfoot and/or rearfoot, referring to the group of bones in the mid- and rear- portions of the foot. A coalition is an abnormal connection, union, or bridge between two of these bones.
The most common tarsal bones affected are the heel bone (calcaneus) and the bones near the ankle (talus and navicular). The two most common coalitions are the talocalcaneal (between the talus and calcaneus) and the calcaneonavicular (between the calcaneus and navicular). Although tarsal coalitions can occur between any two or more bones, all are far less common than the talocalcaneal and calcaneonavicular coalitions.
Types of Coalition
Coalitions may involve an abnormal connection that is:
- bony (synostosis)
- cartilaginous (synchondrosis)
- fibrous (syndesmosis)
- combinations of these types
The extent of the abnormal the abnormal connection can be minimal to extensive, and can even replace the usual location of a joint.
Tarsal coalitions occur congenitally (present since birth) in about 1% of all people and may affect only one foot or both feet. The pain from a tarsal coalition may not arise until adolescence or later and some people with tarsal coalition do not experience any pain.
The abnormal connection between two bones in a tarsal coalition prevents what would otherwise be normal movement. As consequence, the hindfoot and/or midfoot usually are stiff and immobile in a foot affected by a tarsal coalition. As a person ages, the abnormal connection becomes more rigid and stiffer, which is why pain usually arises in adolescence (when the bones of the foot complete their maturation) or later. Because of the restricted movement between two bones, the joints around the coalition are functionally impaired and can develop painful degenerative arthritis as the person ages. In some cases, an injury can disrupt and aggravate a previously non-painful tarsal coalition.
Signs and Symptoms
A person affected by a tarsal coalition is often either flat-footed or high-arched to that side in which the tarsal coalition exists with decreased motion and increased stiffness. Pain is usually present just below the ankle area and made worse with weight bearing high-level activities and certain movements. In some cases, the muscles on the outside of the leg will spasm (tighten during certain movements). If you believe this may pertain to your foot, schedule an appointment with the Weil Foot and Ankle Institute today.
Examination and Diagnostic Testing
CT scan (coronal image) of a patient with a medial
posterior subtalar joint coalition.
The Weil Foot & Ankle Institute has three extremity MRI’s on site at our Des Plaines, Highland Park, and Lincoln Park locations. These extremity MRI’s only take about 30 minutes for the study and only requires the patient put their foot into a painless machine avoiding the uncomfortable claustrophobia that some MRI devices create.
Non-surgical treatment is directed providing a pain free life with day-to-day activities, but does not correct existing mal-alignment of the foot. Your Weil Foot and Ankle physician may recommend custom functional foot orthotics, bracings and/or strappings, and specific shoe gear alternatives.
Ultimately, surgery to remove the abnormal connection can be performed, but its success depends on a number of factors, including the person's age, the extent of the abnormal connection, and whether there is degenerative arthritis in the nearby joints and if any tendinopathy (unhealthy tendon) is present. These factors will determine if the goal of surgery is to resect the abnormal connection or, the alternative and at times better choice, to possible fuse the involved bones together, which typically leads to a lengthier recovery time.