What is Tarsal Coalition of the foot?

  • Tarsal Coalition is a disorder of mesenchymal segmentation that leads to fusion of two or three tarsal bones and lead to a deformity of rigid flatfoot.
  • The tarsal coalition might be:
    1. bony (synostosis).
    2. cartilaginous (synchondrosis).
    3. fibrous (syndesmosis).

Tarsal Coalition is either:

  1. Congenital: most common.
  2. Or Acquired: less common and caused by:
    1. Trauma
    2. Degenerative
    3. Infections
  • Tarsal Coalition’s forms are primarily a talocalcaneal or calcaneonavicular coalition:
    • Calcaneonavicular coalition is most common in children 9 to 12 years of age.
    • Talocalcaneal coalition is more common in children 12 to 14 years of age.
See Also: Tarsal Tunnel Syndrome

Deformity in Tarsal Coalition:

  1. Medial longitudinal arch flattening.
  2. Forefoot abduction.
  3. Hindfoot valgus.
  4. Peroneal spasticity.
  5. Absence of internal rotation of the subtalar joint during walking.
See Also: Anatomical Deformities in Hallux Valgus

Possible causes of pain:

  1. Ossification of previously fibrous or cartilaginous coalition
  2. Micro-fracture at coalition bone interface.
  3. Secondary chondral damage or degenerative changes.
  4. Increased stress on other hindfoot joints.

1. Calcaneonavicular coalition

  • The most common form.
  • Calcaneonavicular coalition is most common in children 9 to 12 years of age (but it probably presents since birth)
  • The abnormal bar runs from the anterior process of the calcaneus just lateral to the anterior facet dorsally and medially to the lateral and dorsolateral extraarticular surface of the navicular.
  • Bar usually is 1.0 to 2.0 cm long × 1.0 to 1.2 cm wide.
  • The talar head might appear small and underdeveloped.
  • Beaking of the dorsal articular margin of the talus (uncommon).
  • The symptoms of Calcaneonavicular coalition usually are:
    1. Dorsolateral foot pain centering around the sinus tarsi.
    2. Difficulty walking on uneven surfaces.
    3. Foot fatigue.
    4. Occasionally a painful limp.
    5. Hindfoot valgus, some loss of the longitudinal arch, peroneal spasm varying degrees of loss of subtalar motion are present in most adolescent patients.

Imaging Study:

  • X-Ray Views:
    1. AP view
    2. Standing lateral foot view
    3. 45-degree internal oblique view
    4. Harris view of heel
      • Findings:
        • Anteater sign elongated anterior process of the calcaneus.
  • CT scan:
    • Determine size, location and extent of coalition.
  • MRI:
    • Helpful to visualize a fibrous or cartilaginous coalition.

Tarsal Coalition Treatment:

  • Nonoperative:
    1. Observation and shoes with medial arch support
      • Asymptomatic flatfoot patients.
    2. A trial of reduced activity or cast immobilization or both:
      • Initial treatment for symptomatic cases
  • Operative:
    1. Coalition Resection with interposition of muscle (extensor digitorum brevis) or fat
      • Persistent symptoms despite prolonged period of nonoperative management
      • Coalition involves <50% of joint surface area.
    2. In advanced case, failed resections, and patients with multiple coalitions, triple arthrodesis is often required.

2. Talocalcaneal coalition

  • Talocalcaneal coalition is a bridge of bone between the sustentaculum of calcaneus and talus.
  • Talocalcaneal coalition is less common than calcaneonavicular coalition.
  • It’s more common in children 12 to 14 years of age.
  • The talocalcaneal bridge ossifies either completely or incompletely when an individual is between 12 and 16 years old
  • Symptoms and clinical examination:
    • Foot fatigue and pain around the hindfoot on increased activity.
    • Loss of the longitudinal arch.
    • Peroneal spasm frequently is present
    • Marked reduction or absence of subtalar motion (compared to calcaneonavicular bar, which may allow varying degrees of subtalar motion).
    • Tenderness in the sinus tarsi, over the talonavicular joint, along the peroneal tendons, and especially medially over the sustentaculum tali.
    • Heel valgus and loss of the normal longitudinal arch usually occur.

Imaging Study:

  • X-Ray Views:
    1. AP view
    2. Standing lateral foot view
    3. 45-degree internal oblique view
    4. Harris view of heel
      • Findings:
        1. Talar beaking on lateral radiograph
        2. C-sign: c-shaped arc formed by the medial outline of the talar dome and posteroinferior aspect of the sustentaculum tali
        3. Dysmorphic sustentaculum appears enlarged and rounded
  • CT scan:
    • Determine size, location and extent of coalition.
    • Size of talocalcaneal coalition based on size of posterior facet using coronal slices
  • MRI:
    • Helpful to visualize a fibrous or cartilaginous tarsal coalition.

Talocalcaneal coalition Treatment:

  • Nonoperative:
    1. Reduced activity 4 to 6 weeks in a short-leg walking cast followed by a period of wearing firm arch supports.
    2. Possibly a corticosteroid injection within the sinus tarsi.
  • Operative:
    1. Coalition Resection with interposition of muscle (extensor digitorum brevis) or fat
      • Persistent symptoms despite prolonged period of nonoperative management
      • Coalition involves <50% of joint surface area.
    2. Subtalar arthrodesis: If more than 50% of the middle facet is involved.
    3. In advanced case, failed resections, and patients with multiple coalitions, triple arthrodesis is often required.