Several accessory bones can be found around the wrist, which may pose a diagnostic challenge. Hereby, we report a unique case of a traumatic fracture of an aberrant os styloideum in a 66-year-old male. The patient presented with a swollen dominant right hand and a hematoma on its anterior and posterior aspects, as a result of a fall on an outstretched hand. The diagnosis was based on a CT scan, which showed a fractured accessory bone between the distal portion of the capitate bone and the base of the third metacarpus. Due to its typical location, the ossicle was identified as os styloideum. The patient was treated conservatively and the symptoms subsided on a short forearm cast after 2 weeks. At a 12-month follow-up, no other episodes were declared. Strong anatomical knowledge and sharing of such cases is essential for proper diagnosis and treatment of this very rare condition.

手腕周围可以发现几块副骨，这可能会给诊断带来挑战。在此，我们报告一例 66 岁男性异常茎突外伤性骨折的独特病例。由于跌倒时手伸直，患者右手肿胀，前侧和后侧有血肿。诊断基于 CT 扫描，结果显示头骨远端和第三掌骨基部之间的副骨骨折。由于其典型位置，小骨被确定为茎突骨。患者接受了保守治疗，两周后在短前臂打石膏后症状消退。在 12 个月的随访中，没有宣布任何其他发作。丰富的解剖学知识和此类病例的分享对于正确诊断和治疗这种非常罕见的疾病至关重要。