Knowing Your Accessory Foot Ossicles and Avoiding Misdiagnoses: A Case Report of Painful Os Vesalianum Pedis.

Os vesalianum pedisis located proximal to the base of the fifth metatarsal. Rarely, this accessory ossicle can be the source of lateral foot pain. There are very few cases of symptomatic os vesalianum pedisdescribed in the literature, and most of them were surgically managed. We report a painful case of os vesalianum pedis managed conservatively. A 25-year-old professional soccer player presented with lateral left midfoot pain. There was no known acute sprain or trauma, and no history of injuries in the left lower limb. The athlete reported both mechanical and inflammatory pain findings and tenderness on the palpation of the fifth metatarsal base. We conducted a radiographic study of the left foot and found an image compatible with os vesalianum pedis​​​​​​​. A right foot X-ray was also performed, and similar findings were reported, although the athlete had no pain. The athlete was treated conservatively, and the return-to-play was seven days.  Due to the unspecific symptoms of our athlete, many diagnoses could be considered such as peroneus brevistendinopathy, lateral plantar fasciitis, ligamentum plantare longumsprain. However, the X-ray findings led us to other possible pathologies, mainly affecting the bone. Integrating clinical and radiological findings is mandatory to achieve a proper diagnosis and avoid mistakenly diagnosing a fracture such as a Jones fracture or pseudo-Jones fracture. Even though os vesalianum pedis​​​​​​​ is usually asymptomatic, this condition can lead to chronic pain. Well-designed conservative management should always be pursued to treat this condition as it might prevent the need for surgery.