The adult tarsal navicular: why it matters.

The adult tarsal navicular is an integral part of the midfoot. Many unique pathological conditions affect its function, and while subtle in their presentation, they can be significant sources of pain and deformity. Recognition of these abnormalities in imaging is essential to obtaining prompt diagnoses and instigating early management interventions. In this pictorial essay, accessory ossicles, stress fractures, avascular necrosis, and tarsal coalitions involving the navicular will be discussed in terms of their characteristic imaging findings. Normal anatomy and biomechanical functional aspects of the navicular will be reviewed and multiple images from plain film, ultrasound, bone scan, computed tomography, and magnetic resonance imaging will be presented. Improved familiarity with the adult tarsal navicular and its various abnormalities will enable radiologists to recognize its importance in the differential diagnosis of midfoot pathology.