Insufficiency fractures of the calcaneus: a diagnostic pitfall for ankle arthritis.

OBJECTIVE To highlight the differential diagnosis between insufficiency fractures (IF) of the calcaneus and arthritis of the ankle. METHODS We retrospectively reviewed clinical charts and imaging findings for 6 patients with 7 IF of the calcaneus who were referred with the diagnosis of ankle arthritis. The main predisposing factors, clinical features, therapy, and outcome were recorded. IF was considered when occurring spontaneously or with minimal trauma. RESULTS All patients were women, with a mean age of 73.8 +/- 6.3 years. The median delay to diagnosis was 6 weeks (25th, 75th percentiles: 1, 12). Two had previous IF at other locations. Three patients had a history of chronic inflammatory conditions while receiving longterm steroid therapy. All complained of moderate to severe pain that interfered with daily activities and was relieved with rest. Physical examination revealed ankle inflammation in all cases. Radiographs were normal in 5 patients. Magnetic resonance imaging (MRI) was diagnostic. All received conservative treatment with complete resolution of symptoms without sequelae. CONCLUSION IF of the calcaneus are relatively rare but can be mistaken for ankle arthritis. MRI is recommended because this type of fracture is difficult to detect on plain films. Although IF have a good prognosis with conservative treatment, increased awareness is of importance for prompt diagnosis and proper management.