Tarsal Coalition

What is tarsal coalition?

The bones of the foot found at the top of the arch, the heel, and the ankle are called the tarsal bones. A tarsal coalition is an abnormal connection between two or more of these bones. These coalitions can form across joints in your child’s foot or can occur between bones that don't normally have a joint between them.

About 25 percent of children with tarsal coalition have a rigid flat foot. The chief symptom of tarsal coalition is pain starting in late childhood or early adolescence.

  • Your child may experience rigidity and stiffness in around their ankle, and a decreased range of motion.
  • Treatment can be non-surgical or surgical, depending on its severity.
  • A severe case of tarsal coalition can interfere with the function of the foot and may interfere with a child’s activities. The condition is not life- or limb-threatening.

What are the tarsal bones?

The tarsal bones in the middle and back of the foot — the calcaneus, talus, navicular, and cuboid — together form joints that are extremely important to proper foot function.

When there’s abnormal growth of bone cartilage or fibrous tissue across these joints (tarsal coalition), a child’s range of motion either decreases or ceases entirely, causing pain and rigidity in the area.

The most common coalitions occur either:

  • across a joint between the talus and calcaneus bones (talocalcaneal coalition, also referred to as a TC bar)
  • between the calcaneus and navicular bones (calcaneonavicular coalition, also referred to as a CN bar)

Calcaneonavicular coalitions are more common than talocalcaneal coalitions. Together, these two types account for about 90 percent of all coalitions. There are other more rare types, as well. More than 50 percent of the time, tarsal coalition occurs in both feet. Sometimes both types of coalition are present in the same foot.

What causes a tarsal coalition?

Tarsal coalition can be a genetic error in the dividing of embryonic cells that form the tarsal bones during fetal development can sometimes be triggered by:

  • trauma to the area
  • infection
  • self-fusion of a joint caused by advanced arthritis (rare in children)

What are the symptoms of a tarsal coalition? When do they occur?

Even though most children with tarsal coalitions are born with them, painful symptoms typically set in sometime between the ages of 8 and 16. During late childhood and early adolescence children’s bones change from mostly cartilage to mostly bone (a process known as ossifying). During this period, the hardening (calcifying) tarsal coalition grows more rigid and painful. Sometimes symptoms don't flare up until early adulthood.

While each child may experience symptoms differently, the most common symptoms of a tarsal coalition include:

  • pain, typically on the outside and top of the foot (though some children have no pain)
  • flat feet or a flat foot (though not all children with flat feet have a tarsal coalition)
  • rigidity and stiffness in the affected foot
  • muscle spasms

How common is tarsal coalition?

Experts estimate that about 3 to 5 percent of people have a tarsal coalition. About 50 percent of these individuals have it in both feet.

How serious is tarsal coalition?

The answer to this question depends on the severity of the condition and your child’s level of activity. If sports are central to your child’s life, tarsal coalition could be viewed as a serious problem. If your child has only occasional aches, such as when running in gym class, and sports are not very important to them, the condition probably will not have a profound impact on their life.

A severe case of tarsal coalition can pose functional problems, make walking difficult, and may alter a child’s activity level. While treatment is recommended to improve function and relieve pain, the condition is not life-threatening or limb-threatening.

What if tarsal coalition goes untreated?

Over time, a child, teen, or young adult may experience enough pain that they can’t do the activities they enjoy. Later in life, they may have a very stiff foot (indicating a large coalition). The foot may be so stiff and painful that surgical repair is no longer an option. In such cases, a joint fusion would be the remaining option to alleviate pain.

Who’s at risk for developing tarsal coalition?

Tarsal coalition is a genetically determined condition. If one of a child’s parents has the condition, there is a chance that the child will also have it. If it occurs sporadically (by chance), it means that a genetic mutation took place during a child’s fetal development.

There is no genetic test available yet for tarsal coalition. Many people living with tarsal coalitions have few or no symptoms. Treatment of tarsal coalitions is only for symptomatic ones, therefore, evaluation for tarsal coalition occurs only for those people presenting with symptoms.

How we care for tarsal coalition

As part of the national and international referral Orthopedic Center at Boston Children's Hospital, our Lower Extremity Program offers comprehensive assessment, diagnosis, and treatment of lower limb conditions for children of all ages. Our specialists start with a conservative, non-surgical approach. If a case requires surgery, our surgical team has extensive experience correcting tarsal coalition, as well as other issues of the foot. We provide expert diagnosis, treatment, and care for every severity level of tarsal coalition to ensure our patients can live full, pain-free lives.

Tarsal coalition glossary

Terms to know
  • arthritis: joint inflammation and damage, resulting in pain, swelling, stiffness, and limited movement. Arthritis can occur when a joint’s cushioning cartilage wears away
  • bilateral: both of two sides
  • bone bridge: another term for the coalition that forms between the tarsal bones
  • calcify: harden into bone by the deposit of calcium salts into cartilage; ossify
  • CT scan (computerized tomography scan): the gold standard for the diagnostic imaging of tarsal coalitions; uses a combination of x-rays and computer technology to produce cross-sectional horizontal and vertical images (called "slices") of the body
  • diagnosis, diagnostics: identifying disease or injury through examination, testing, and observation
  • gait: manner of walking
  • Hale Family Center for Families at Boston Children’s Hospital: dedicated to helping families find the information, services, and resources they need to understand their child’s medical condition and take part in their care
  • lower extremities: parts of the body from the hip to the foot — includes hip, thigh, ankle, leg, and foot
  • MRI (magnetic resonance imaging): a diagnostic imaging tool that produces detailed images of organs and structures within the body
  • onset (of signs or symptoms): the first appearance of signs or symptoms
  • orthopedic surgeon, orthopedist: a doctor who specializes in surgical and non-surgical treatment of the skeletal system, spine, and associated muscles, joints, and ligaments
  • orthopedics: the medical specialty concerned with diagnosing, treating, rehabilitating, and preventing disorders and injuries to the spine, skeletal system, and associated muscles, joints, and ligaments
  • ossify: a natural progression as a child grows in which cartilage turns into bone or bony tissue
  • prognosis: outlook for the future
  • resection: a surgical procedure in which an organ or body structure is removed
  • sporadic: by chance
  • tarsal coalition: an inherited condition in which there’s an abnormal connection between two or more of the tarsal bones. These coalitions can form across joints of the foot or can occur between bones that don't normally have a joint between them.
  • x-rays: a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film; “standing” x-rays are x-rays taken while the child is standing up, as in diagnosing tarsal coalition

See our extensive Glossary of Orthopedic Terms.