Osteoid osteoma of os calcis. Diagnosis is made by computerized tomography.

The authors describe a young college student with hind foot pain that was initially thought to be degeneration of the subtalar joint. Initial x-rays showed a small "cyst" but were initially interpreted as being normal. A bone scan clearly showed a focal area of increased uptake. It was only with computerized tomography (CT) that the diagnosis of osteoid osteoma was made. This was resected and now, two years later, the patient is symptom-free. The patient had been scheduled for a subtalar arthrodesis, which was avoided fortunately when the correct diagnosis was made by CT scan.