Case: We report the case of a 39-year-old man who sustained an acute fracture of an os hamulus proprium, which was treated with open surgical excision after nonoperative treatment was unsuccessful. At the most recent follow-up, at 6 years after surgery, the patient was asymptomatic and maintained full function of the hand and the wrist.
Conclusion: An os hamulus proprium is often confused with a fracture of the hook of the hamate, and little information exists in the literature regarding these accessory ossicles. To our knowledge, an os hamulus proprium fracture has not previously been described in the literature.