Case of the Month

CLINICAL

24 year old male with hindfoot stiffness

FINDINGS

Xrays of the ankle showed a continuous C sign.
CT confirmed Talocalcaneal coalition with involvement of the middle subtalar facet with overgrowth and joint space irregularity. The coalition is either fibrous or cartilaginous as there is not a bony bridge present.

DIAGNOSIS

Talocalcaneal coalition which is either cartilaginous or fibrous involving the middle subtalar joint.

DISCUSSION

Tarsal coalition is the result of abnormal fusion between two or more tarsal bones. The fusion can be bony, cartilaginous or fibrous. The estimated incidence is approximately 1% and occurs bilaterally in about 50%. The two most commonly involved joints are the Calcaneonavicular and Talocalcaneal.

People often present in the second decade of life and present with pain, hindfoot stiffness. Xrays are usually the first step with MRI and CT useful for confirmation and for determining the type of coalition.

Xray signs of Talocalcaneal coalition.

• Continuous C sign
• Talar beak

Calcaneonavicular Coalition on Xray

• Prominent anterior process of the calcaneous (described as ant eater nose).

TREATMENT

Treatment includes conservative management, orthotics and surgery