2001 OITE Question 197

Question

A 16 year-old boy has had pain in the lateral ankle and hindfoot after sustaining a minor ankle sprain 6 months ago. The pain is worse with twisting activity of the foot. Examination reveals normal alignment of the foot and ankle. An AP radiograph of the foot and ankle are normal. A lateral radiograph is shown in Figure 61. What is the most likely cause of his persistent pain?


1. Fracture of the lateral process of the talus


2. Fracture of the anterior process of the calcaneus


3. Fracture of the tibial plafond


4. Talocalcaneal coalition


5. Stress fracture of the calcaneus

Figures

Answer (click for answer)

Correct Answer: 4

Tarsal coalition, a fibrous, cartilaginous, or bony connection between 2 or more tarsal bones that results from a congenital failure of differentiation and segmentation, is a cause of stiff, painful flatfoot. The most common types are calcaneonavicular and talocalcaneal. These occur with equal frequency and account for almost 90% of the total number of coaltions in the foot. The onset of symptoms usually correlates with the coaltion from cartilage to bone at age 8-10 years for calcaneonavicular coalitions, and between 12-16 years for talocalcaneal coalitions. The most common site of coalition is the medial facet. The pain may have its onset with some unusual activity, trauma, or may be insidious. The pain can be in the sinus tarsi region or in the ankle region akin to an ankle sprain!

A fracture of the lateral process of the talus often mimics a lateral ankle sprain on exam with lateral tenderness and ecchymosis. Usually this can be seen on routine x-ray evaluation. A tibial plafond fracture should be picked up on x-rays. A fracture of the anterior process of the calcaneus is an avulsion fracture due to an inversion injury of the ankle- again usually picked up on x-rays. A stress fracture of the calcaneus in unlikely with the history given.

Reference: F&A OKU, pages 70-71, 210-211, 215