The Missing Navicular: Bilateral Navicular Agenesis Presenting as Adult-acquired Flatfoot with Subtalar Arthritis: A Case Report.

INTRODUCTION: Anatomical variations of the navicular bone, including accessory ossicles, hypoplasia, and complete absence, can influence foot biomechanics and clinical presentation. Complete absence of the navicular bone is exceptionally rare and may not be readily recognized. CASE REPORT: We report a rare case of bilateral navicular agenesis in a 34-year-old male presenting with chronic foot pain and deformity. Imaging revealed a complete absence of the navicular bone with altered midfoot biomechanics and secondary degenerative changes. The patient underwent subtalar arthrodesis with midfoot correction, achieving a stable plantigrade foot. At 12 months follow-up, there was significant pain relief and a satisfactory functional outcome. CONCLUSION: Navicular agenesis should be considered in atypical cases of flatfoot deformity. Accurate diagnosis using advanced imaging is essential, and surgical management can provide good functional outcomes.