Red Herring in Orthopedics: A Case Report on Painful Os Vesalianum Pedis Masquerading as an Avulsion Fracture of 5th Metatarsal and Review of Literature

Introduction: Os vesalianum pedis (OVP) is a rare accessory ossicle of the foot located proximal to the base of 5th metatarsal. It is usually asymptomatic but can mimic an avulsion fracture of proximal 5th metatarsal and is an infrequent cause of lateral foot pain. There have only been 11 cases of symptomatic OVP reported in the current literature. Case Report: Our patient, a 62-year-old male presented with lateral foot pain following an inversion injury of his right foot, with no history of any previous trauma. What was initially mistaken as an avulsion fracture of the 5th metacarpal base was later revealed to be an OVP on contralateral X-ray. Conclusion: Treatment is mostly conservative, but surgical excision can be done in cases following failed non-operative treatment. In the context of trauma, OVP must be differentiated from other causes of lateral foot pain such as Iselin’s disease and avulsion fractures of base of 5th metatarsal. Understanding the various etiologies of the condition and what those etiologies are usually related to can help prevent unnecessary treatment.