Tarsal coalition is a condition where bones in the foot are abnormally connected, impacting normal foot function. This abnormal connection can lead to discomfort and limited movement, often becoming noticeable during childhood or adolescence.
What is Tarsal Coalition?
Tarsal coalition refers to an unusual union between two or more bones located in the midfoot and hindfoot regions. These bones, known as tarsal bones, typically include the talus (ankle bone), calcaneus (heel bone), and navicular bone, essential for proper foot movement and stability. The abnormal connection can take several forms: a fibrous bridge, a cartilaginous link, or a complete bony fusion.
The most common types of tarsal coalition occur between the talus and calcaneus (talocalcaneal coalition) or between the calcaneus and navicular bones (calcaneonavicular coalition). These two types account for approximately 90% of all reported cases. While present from birth, symptoms often become apparent as the cartilaginous connection hardens into bone over time.
How Tarsal Coalition Develops
Tarsal coalition originates as a congenital condition. It arises from a failure in the normal segmentation process during fetal development. In typical development, the bones of the foot separate to form distinct joints, but in individuals with tarsal coalition, this separation does not occur completely.
Instead, primitive mesenchymal tissue, which should form separate bones, remains connected, leading to the formation of a bridge between two or more tarsal bones. While the coalition is present at birth, it may initially be composed of soft cartilage or fibrous tissue, which gradually ossifies, or turns into bone, as a child grows.
Recognizing Tarsal Coalition
Symptoms of tarsal coalition typically emerge during late childhood or early adolescence, often between the ages of 8 and 16, as the foot bones mature and the coalition ossifies. Common complaints include foot pain, stiffness, and muscle spasms, particularly in the outer leg due to the foot’s abnormal position. The pain often intensifies with increased activity, such as walking or running.
Individuals may also exhibit a characteristic “rigid flatfoot” appearance, where the arch of the foot does not flatten or correct itself when standing or walking. This rigidity can lead to difficulty walking on uneven surfaces and may contribute to recurrent ankle sprains because the foot’s natural shock absorption and flexibility are compromised.
Diagnosing Tarsal Coalition
Diagnosis of tarsal coalition begins with a detailed medical history and a thorough physical examination of the foot and ankle. During this examination, the doctor will assess foot flexibility, observe gait abnormalities, and check for a rigid flat arch that does not improve when standing on toes. Limited motion in the subtalar joint, which is located below the ankle, is a common finding.
Imaging tests are essential for confirming the diagnosis and determining the specific type and extent of the coalition. X-rays are often the initial imaging tool, providing an overview of the foot bones. However, computed tomography (CT) scans offer greater detail of the bones and are effective for visualizing tarsal coalitions. Magnetic resonance imaging (MRI) can provide images of both bones and soft tissues, which is particularly useful for identifying fibrous or cartilaginous coalitions that may not be clearly visible on X-rays or CT scans.
Treatment Approaches for Tarsal Coalition
Treatment for tarsal coalition begins when symptoms cause discomfort or functional limitations, as many individuals with the condition remain asymptomatic. Conservative approaches are the initial approach. Rest from activities that aggravate the pain, often for several weeks, helps reduce inflammation and stress on the affected area. Anti-inflammatory medications can also help manage pain and swelling.
Orthotics, such as shoe inserts or arch supports, can stabilize the foot and redistribute pressure, while a temporary boot or cast may be used to immobilize the foot and relieve stress on the tarsal bones. Physical therapy can help improve foot mechanics and reduce muscle spasms. If these non-surgical methods do not provide sufficient relief, surgical intervention may be considered.
Surgical resection involves removing the abnormal coalition and often interposing tissue from another area to prevent recurrence. This procedure restores more natural foot motion and relieves pain. For more extensive coalitions, those with significant deformity, or in cases where arthritis has developed, joint fusion may be performed. Fusion involves permanently joining the affected bones to eliminate painful motion, though it results in a stiffer foot. Surgical recovery can vary, typically taking several months, to improve quality of life and reduce pain.