Navicular stress fractures (NSFs) are relatively uncommon, and predominantly affect athletes. Patients complain of vague pain, bruising, and swelling in the dorsal aspect of the midfoot. Os supranaviculare (OSSN) is an accessory ossicle located above the dorsal aspect of the talonavicular joint. There have been few previous reports of NSFs accompanied by OSSN. Herein we report the case of a patient with OSSN who was successfully treated for an NSF. A 34-year-old Asian man presented with a 6-month history of insidious-onset dorsal foot pain that occasionally radiated medially toward the arch. The pain worsened while sprinting and kicking a soccer ball with the instep, whereas it was temporarily relieved by rest for a week and analgesics. Plain radiographs of the weight-bearing foot and ankle joints revealed a bilateral, well-corticated OSSN. Computed tomography (CT) revealed a sagittally oriented incomplete fracture that extended from the dorsoproximal cortex to the center of the body of the navicular. The OSSN was excised and the joint was immobilized with a non-weight-bearing cast for 6 weeks, followed by gradual weight bearing using a boot. The 5-month follow-up CT scan demonstrated definite fracture healing. At the 1-year follow-up, the patient's symptoms had resolved, the American Orthopedic Foot and Ankle Society midfoot score had improved from 61 to 95 points, and the visual analog scale pain score had improved from 6 to 0. We describe a rare case of NSF accompanied by OSSN. Because of the fracture gap and biomechanical properties of OSSN, OSSN was excised and the joint was immobilized, leading to a successful outcome. Further research is required to evaluate the relationship between NSFs and OSSN, and determine the optimal management of NSFs in patients with OSSN.
Keywords: os supranaviculare; stress fracture; tarsal navicular.