Variations in calcaneonavicular morphology demonstrated with radiography.

Purpose: To determine and classify radiographically demonstrated variations in calcaneonavicular morphology and to estimate prevalence in a clinically relevant patient population.

Materials And Methods: Retrospective review was performed of foot radiographs obtained during diagnostic evaluation of 460 consecutive patients who presented to the emergency department with acute foot pain. Variations in calcaneonavicular morphology depicted on the medial oblique view (obtained at a 45 degrees angle) were classified into four groups according to morphologic type (types 1-4), and the prevalence of each type was calculated. Chi2 analysis was used to compare the prevalence of each type in male patients and in female patients. One-way analyses of variance were used to compare mean ages of patients for each type and mean calcaneonavicular gaps for each type.

Results: The prevalence of morphologic types 1, 2, and 3 was 94.3%, 2.8%, and 2.8%, respectively. The combined prevalence of types 2 and 3 (calcaneonavicular coalitions produced by synchondrosis and syndesmosis, respectively) was 5.6% (95% CI: 3.5%, 7.8%). There were no patients with type 4 morphology (synostosis). The numbers of male patients and female patients with morphologic types 1-3 were approximately equal (P =.9), and there was no statistically significant correlation between any of these three morphologic types and patient age (P =.2). The calcaneonavicular gap was significantly narrower in types 2 and 3 than in type 1 (P =.01), which was characterized as the normal morphology.

Conclusion: The general prevalence of calcaneonavicular coalition (synchondrosis and syndesmosis) may be greater than previously reported, but further research is needed to prove the validity of this hypothesis.