Talar Beak
Tarsal Coalition

General Considerations

• Rare (1% incidence)
• Fusion of two or more tarsal bones in the hindfoot (talus and calcaneous) or midfoot (cuboid, navicular and 3 cuneiforms)
• Most common coalitions (90% of total) are
  • Calcaneous and navicular (calcaneonavicular)
• Calcaneous and talus (talonavicular)
• Fusion may be congenital or acquired
• Congenital form is familial
• Autosomal dominant with near complete penetrance
• Bilateral 50% of time
• More common in males than females
• Acquired form may be due to trauma, infection, arthritis, surgery
  

Types

• Complete coalition
  • Bony (synostosis)
• Incomplete coalition
  • Cartilaginous (synchondrosis)
• Fibrous (syndesmosis)
  

Clinical Findings

• Most are asymptomatic
• When symptomatic, symptoms begin in 2^nd decade of life
• Pain is most common symptom
  • Made worse by physical activity
• Restricted range of motion
• Muscles spasms
  

Imaging Findings

• Conventional radiography of the foot is the study of first choice
• Calcaneonavicular fusions should all be evident on a 45° internal oblique view
  • Bridge is usually from anterolateral aspect of calcaneous to dorsolateral aspect of navicular
• With fibrous and cartilaginous coalition, the joints may be narrowed, sclerotic and irregular
• Talocalcaneal coalition may be more difficult to see
  • Most often involves junction between the middle facet of the talus and the sustentaculum talus
• Talar beak presumably occurs because of limitation of motion in subtalar joint
• At insertion of talonavicular ligament, periosteal reaction develops
• Beak not present in all patients with talocalcaneal coalition
• Pes planus deformity is common
• Hypoplasia of the sustentaculum tali may occur
• MRI is most sensitive to fibrous and cartilaginous fusion
  

Treatment

• Conservative treatment is utilized first
  • NSAID (non-steroidal anti-inflammatory drugs)
• Steroid injections
• Orthotics
• Surgical interventions most commonly involve resection of the bridge and placement of fat, muscle or tendon in place of the coalition
• Arthrodesis is sometimes used with severe coalitions
  

Complications

• Cause of spastic peroneal flatfoot
• Bony bridge can fracture

Talar Beak and Tarsal Coalition. The white arrow points to a "talar beak" seen on the dorsum of the talus which should raise suspicion for the presence of a tarsal coalition. The oblique view of the same foot demonstrates bony bridging between the tarsal navicular and the calcaneous.
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Tarsal Coalition  eMedicine Eric A Wang, MD, Amilcare Gentili, MD, Sulabha Masih, MD,  and Matthew C Wang, BS