What Is a Tarsal Coalition?
Tarsal coalition (TC) is an abnormal connection between two or more bones which is present at birth. The connection may be made of fibrous tissue, cartilage, or bone. Most people with TC do not have symptoms, however, occasionally this abnormal connection leads to decreased motion in the joints of the foot and can be painful. As one joint loses motion, surrounding joints can develop arthritis.
TC usually affects children and teens but can appear in adults also. It occurs in 1-6 percent of the population and about half of patients have problems with both feet.
While TC may be present at birth, symptoms usually are delayed until the bone matures. This explains why most patients experience pain gradually. The typical patient is a child or teen with foot stiffness and pain with activity. Walking on uneven surfaces may cause discomfort. Frequent ankle sprains also may be a clue in diagnosing TC. Patients with TC have pain and limited side-to-side-joint motion and may have flat feet.
Tarsal coalition is caused by a gene mutation. The bones of the feet are divided into three parts: the hindfoot (back of the foot), midfoot (middle of the foot), and forefoot (front of the foot). Tarsal coalition involves the bones in the midfoot and hindfoot. Of these bones, the calcaneus, talus, and navicular are most commonly involved. Most tarsal coalitions are one of two types:
- Talo-calcaneal coalition: In this case the talus (lower bone of the ankle) and the calcaneus (heel bone) have not fully separated.
- Calcaneo-navicular coalition: In this case the front part (beak) of the calcaneus is attached to the outside and lower part of the navicular bone.
TC can be diagnosed with X-rays of the foot and ankle. In some cases, a CT scan or MRI can help in the diagnosis. A CT scan will best determine the extent of a bony coalition while an MRI will be more useful in diagnosing small, fibrous or cartilage coalitions.
In asymptomatic coalitions, observation is all that is needed. In almost all symptomatic cases, non-surgical treatment is the first option. Avoiding aggravating activities or walking on uneven ground often is helpful. A supportive shoe or orthotic, as well as anti-inflammatory medications also can relieve symptoms. A high-top shoe or ankle brace will provide stability. Occasionally, immobilization with a cast and walking boot is necessary.
When conservative management has been exhausted, surgical options should be considered. The type of surgery will depend on the location and size of the coalition, as well as the presence of any arthritis at the joints near the coalition, and expectations and activity level of the patient.
Resection of the coalition is performed to decrease pain and improve motion between the affected bones. Younger patients tend to do better with resection of a coalition. In large coalitions or if arthritis is present, a fusion of the affected joints is necessary. This improves pain but does not improve motion.
A walking cast or boot is used to protect the surgical site. If a fusion procedure is performed, a longer period of immobilization and non-weightbearing is necessary. This is followed by physical therapy to restore range of motion and strength. Arch supports or orthotics also can be helpful in stabilizing the joint, even after surgery. Although it may be up to a year to fully recover, most patients have pain relief and improved motion after surgery.
Risks and Complications
All surgeries come with possible complications, including the risks associated with anesthesia, infection, damage to nerves and blood vessels, and bleeding or blood clots. In fusion surgery there is a small risk that the bones will not fuse together.
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