Anterior process calcaneal fractures: a systematic evaluation of associated conditions.

OBJECTIVE: The objective was to evaluate the association, by MRI, of anterior calcaneal process fractures with tarsal coalitions, ankle sprains, and bifurcate ligament abnormalities.

DESIGN AND PATIENTS: A retrospective review of 1,479 foot and ankle MR images was performed, over a period of 5 years, for isolated anterior process fractures of the calcaneus. Fifteen 1.5-T MR examinations were systematically evaluated by two radiologists in consensus. Marrow edema patterns, presence of a calcaneonavicular coalition, as well as bifurcate and anterior talofibular ligaments, were evaluated.

RESULTS: There were 15 fractures of the anterior calcaneal process with an incidence of 1%. The average patient age was 51 years (range 25-82). Twelve patients were women and 3 were men. The majority of the fractures (14 out of 15) presented as an edema pattern on T2-weighted images, either diffuse (9 out of 15), or vertical (5 out of 15). One case did not show marrow edema, but rather a hypointense line. Nine patients (60%) demonstrated calcaneonavicular coalition and anterior calcaneal process fracture. In 6 patients (50%) the anterior talofibular ligament (ATFL) was thickened. Three patients did not have axial images, and were classified as non-conclusive for the ATFL evaluation. The bifurcate ligament was thickened with hyperintense signal demonstrating a sprain in 9 out of 13 (69%). Only 2 patients (16.5%) had an anterior calcaneal process fracture without any associated abnormality.

CONCLUSIONS: We believe that there is a probable association of anterior process fractures and calcaneonavicular coalitions. We also feel, based on our results and the prior literature that there is likely also an association with both ATFL injuries and bifurcate ligament injuries.