[C-sign and talocalcaneal coalition].

Area of Science:

• Orthopedics
• Radiology
• Podiatry

Background:

• Talocalcaneal coalition is an uncommon condition (<1%) characterized by an abnormal bony or fibrous union between the talus and calcaneus.
• It typically manifests in the second decade of life, leading to pain, restricted subtalar motion, and associated foot deformities.

Observation:

• A case of talocalcaneal coalition was incidentally discovered in a 20-year-old male following an ankle fracture.
• The presence of the 'C-sign' on initial imaging prompted further investigation with CT, confirming the diagnosis.

Findings:

• Radiographic diagnosis can be challenging, as standard X-rays may appear normal.
• Secondary signs on lateral ankle radiographs, such as the 'C-sign', indicate abnormal joint mechanics and warrant further evaluation with CT or MRI.

Implications:

• Awareness of secondary radiographic signs is vital for early and accurate diagnosis of talocalcaneal coalition.
• Prompt diagnosis facilitates appropriate management, potentially preventing long-term complications associated with subtalar joint dysfunction.