A 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 lack of motion or absence of motion is due to abnormal bone, cartilage or fibrous tissue growth across a joint. When excess bone has grown across a joint there is usually little or no 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 or in surrounding joints.
The decreased motion can cause pain in surrounding joints as they try to compensate for the affected joint. When one joint has restricted motion the surrounding joints will be stressed more than normal. This is an attempt to “take up the slack” for the diseased joint.
Tarsal coalitions can occur outside of a joint as well. This is referred to as a bar. A bar connects two bones that don't normally touch or have a joint between them. The bar will limit motion in surrounding joints causing abnormal wear and tear to the joints of the foot. This can lead to early arthritis and pain. The bar itself can be painful as well if it is incomplete, traumatized during walking, sporting activities, or an accident.
In the foot, the bones found at the top of the arch, the heel' and the ankle are referred to as the tarsal bones. Thus, 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 and passed down from generation to generation. All coalitions are not inherited though. They can also arise from outside sources such as arthritis, infections, trauma and abnormal bone growth. These outside causes are much less frequent.
Patients with a painful tarsal coalition commonly describe an aching sensation deep in the foot near the ankle or arch. In many cases, muscle spasm on the outside of the affected leg is present. This is a natural reaction of the body as it tries to limit the painful motion occurring in the foot. Patients may notice that the affected foot is not as flexible and appears significantly more flattened when compared to the other foot. This only holds true if only one foot is affected, as it is common for both feet to be affected. All flat-footed people do not have tarsal coalitions. There are many causes of flat feet.
Symptoms most commonly appear in the teenage or early adult years depending on the location of the coalition. It should be noted that not all tarsal coalitions become symptomatic. The onset of symptoms may be delayed into adulthood.
Diagnosis of a tarsal coalition can usually be made from symptoms described by the patient to the doctor. X-rays are usually taken and in most cases a CT scan or MRI will confirm the diagnosis and provide valuable information regarding the type of coalition, its location, and how the joints have been affected.
There are a variety of methods to treat a tarsal coalition depending on the severity of the condition, the age of the patient and which joint is affected. Conservative treatment involves non-surgical treatment options. Conservative treatment is directed toward reducing motion in the affected joints to decrease pain and muscle spasm. Orthotics (shoe inserts) are commonly used accomplish this decrease in motion. Physical therapy and anti-inflammatory medication may be utilized as well. Cortisone injections in the affected area may provide relief for an indefinite period of time. These conservative methods of treatment may or may not provide long-term relief.
If symptoms do persist surgical correction is often entertained. Surgical intervention will vary depending on the type of coalition, its location, and the amount of arthritis it has caused in the foot. Surgery can involve removing the coalition to allow for more normal motion between the bones. Many times surgery may involve fusing the affected joint or surrounding joints. This is designed to limit or completely stop the painful motion of the affected joints.
Recovery from surgery often involves a period of non-weight bearing on crutches and utilization of a cast. Physical therapy will often be used once the normal bone healing is complete to restore muscle tone and full available range of motion.(For more information see Hindfoot and Ankle surgery.