Tarsal Coalition - Causes, Diagnosis, and Treatment

Introduction

An abnormal union of two or more foot bones is called a tarsal coalition. It is primarily a congenital condition, which can be a complete or partial fusion of bones in the midfoot or hindfoot region. It is a rare condition, commonly affecting males, involving both feet, but in some cases, it may be unilateral. It can be an osseous, cartilaginous, or fibrous union between the tarsal bones.

What Are Tarsal Bones?

Tarsal bones are calcaneus (heel bone), talus (ankle bone), navicular, cuboid, medial, middle and lateral cuneiform bones. They function together to help in the proper movement of the foot. The hind foot is formed by calcaneus and talus; the midfoot is formed by cuboid and cuneiform bones. Navicular is intermediate between the two groups.

What Are the Types of Tarsal Coalition?

• Tarsal coalition can be classified based on the type of tissue that bridges between the bones, such as osseous or bone tissue (synostosis), cartilage (synchondrosis), and fibrous tissue (syndesmosis).

• It can also be classified as a juvenile and adult tarsal coalition based on osseous (bone) maturity.

• Anatomically or based on the bones involved in fusion, the tarsal coalition can be classified as:

Talo calcaneal (fusion of talus and calcaneus), calcaneonavicular (fusion of calcaneus and navicular bones), post talocalcaneal (middle facet of talocalcaneal), cubonavicular (fusion of cuboid and navicular), talonavicular (fusion of talus and navicular), calcaneocuboid (fusion of calcaneus and cuboid bones). Calcaneonavicular is the most common type of tarsal coalition, which becomes evident or symptomatic around 8 to 12 years, and talocalcaneal, around 12 to 15 years of age.

What Are the Causes of a Tarsal Coalition?

• Causes for the tarsal coalition are primarily congenital, the reason is unknown, or it may be due to gene mutation of the cells that form tarsal bones, which results in failure of embryonic segmentation of tarsal bones. It is usually asymptomatic till childhood or adolescence because of the soft-growing cartilage. With growth, the cartilage ossifies or mineralizes to develop into a hard mature bone. If there is a coalition between the bones, it also mineralizes, with the bridging of fibrous or osseous tissue, which leads to stiffness and pain.

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• If any one of the parents has a tarsal coalition, the child is susceptible to developing the condition.

• In adults, a tarsal coalition can be due to infections, trauma, arthritis, or a previous history of injury to the foot.

What Are the Signs and Symptoms of the Tarsal Coalition?

Even though the condition is present from birth, it becomes symptomatic in late childhood or adolescence, around 9 to 16 years, when there is a limitation of movement. Some of the signs and symptoms include

• Difficulty and fatigue in walking or standing

• Stiffness or rigidity of the foot and ankle.

• Walking with a limp.

• Recurrent ankle sprains and spasms

• Pain below the ankle region and around the midfoot and hindfoot region.

• Increased pain during physical activities like jumping, running, jogging, etc.

How Is the Tarsal Coalition Diagnosed?

The doctor notes the patient's medical history and performs a complete physical examination of the foot and ankle to check the flexibility and posture of the foot while standing and walking.

• Patients usually have a flat foot that does not reconstitute on pushing toes and raising the heel. A reverse Coleman block test is performed to evaluate the flexibility of the hindfoot and the forefoot pronation. The patient is asked to place the foot on a wood block measuring 2.5 to 4 feet in thickness. The position will be such that the lateral border and the heel rest on the block, whereas the first to third toes and the surrounding structures will hang freely.

• X-rays are advised in anterior-posterior view, standing lateral view, and oblique view to confirm the diagnosis. The oblique view generally confirms the calcaneonavicular coalition.

• Computed tomography (CT Scan) is the gold standard for diagnosing tarsal coalition, which helps to view the irregular bars formed by the tissues, irregularity, and narrowing of the bone interfaces and to assess the location, size, and extent of the coalition and rule out any other deformities.

• Magnetic resonance imaging (MRI) is advised to visualize the surrounding structures and to determine the type of tissue associated with the bridging of the bones.

How Is the Tarsal Coalition Treated?

Treatment is carried out only if the condition is symptomatic, and depending on the age and severity, it can be treated conservatively or by surgical methods. Conservative management includes:

• Discontinuation of physical activities for around three to six weeks reduces stress and pain. Non-steroidal anti-inflammatory drugs like Ibuprofen are prescribed to relieve pain and inflammation. Anesthetic injections may be given to relieve muscle spasms.

• Weight reduction and lifestyle modification in the case of overweight patients.

• Using orthotics, such as crutches, medial arch support, and shoe inserts like heel cups and wedges, can stabilize the foot by limiting movement and distributing the weight away from the joint, reducing pain and discomfort.

• Immobilization by cast boot or below-knee walking cast for four to six weeks or a temporary boot minimizes the stress on the tarsal bones.

• In some cases, steroid injections like cortisone are injected into the joint, along with other options, to provide temporary pain relief.

• Stretching exercises and range of motion therapy improve flexibility and stability.

Surgical management is necessary if the tarsal coalition involves more than fifty percent of the joint area or the non-operative methods are unsuccessful. The surgical procedures depend on the location, size, and signs of arthritis. The goal is mainly to remove the abnormal growth and establish a normal range of motion. Surgical treatment includes:

• Resection: It involves the removal of the coalition and replacement with tissue from another area of the body. It is the most commonly followed surgery in patients with no signs of arthritis, as it restores normal function and provides symptomatic relief.

• Fusion: Patients with a severe coalition and signs of arthritis are treated by fusion which involves fixing the bones with large screws, pins, or screws and plate devices; it limits the movement of the painful joints and places the bone in the proper position.

• Triple Arthrodesis: In cases of failure of resection or severe joint injuries, it is the fusion of the three joints of the hindfoot; it reduces pain and establishes a proper gait.

Immobilization is done with the cast for around four to six weeks, followed by replacement with walking boots and physical therapy.

What Are the Complications of the Tarsal Coalition?

Tarsal coalitions, when left untreated, can increase the intensity of pain and discomfort and hamper daily activities. It can also lead to arthritis or permanent stiff feet. Complications of the surgery include infection and poor wound healing, injury to the nerve, and hematoma (blood clot).

Conclusion

Tarsal coalition is a rare congenital condition characterized by the fusion of two or more bones of the foot, associated with pain around the ankle region; it is managed by symptomatic treatment and, in complex cases, by surgeries. The patient might take a few months to recover completely, but the treatment is known to have a good outcome and improvement.