Fractures of the carpal bones are rare, with the exception of the scaphoid bone. Of all the carpal bones, the hamate accounts for only 2% of fractures, while the scaphoid fractures would be 70%. Hamate fractures are classified based on the Milch classification which takes into account the part of the bone fractured. Fractures of the hook of Hamate are commonly seen in golfers, baseball players, and racket sports players. It is also very common in patients with falls and crash injuries In comparison, body fractures of the hamate are more associated with the act of a clenched fist striking a wall.
Hamate fractures can be difficult to treat and the diagnosis is often missed. In fact, it can take anywhere up to 5 weeks, but the average is about 10 days. It typically causes hypothenar pain worsened by palpation or gripping. The hook of the hamate pull test is performed to assess for hook fractures, and it is deemed positive if the resisted flexion of the fourth and fifth digits displaces the fracture and causes pain. A fracture of the Hamate can damage the ulnar nerve given its close proximity, causing additional symptoms of paresthesia or weakness.
Plain film radiography is performed for the diagnosis of these injuries. There is an overlap of the hook of the hamate on the body, which makes the radiological diagnosis quite difficult. Computed tomographic (CT) scan can be performed to assist in such cases and for preoperative planning.
The treatment of hamate fractures is dependent on the degree of the displacement and fracture location. For minor, nondisplaced hamate hook fractures, short arm cast immobilization is usually sufficient, along with close clinical follow-up to ensure there is no non-union. Displaced hook fractures or those that are associated with nerve or tendon irritation require a more involved approach. Excision needs to be performed in these settings, and it does not adversely affect grip strength or wrist range of motion. Excision is actually preferred to open reduction internal fixation. Hamate body fractures, on the other hand, are treated with a short arm cast for 4 to 6 weeks, if nondisplaced. Displaced hamate body fractures actually require an open reduction and internal fixation with either compression screws or low-profile plates. In some cases, temporary fixation across the carpometacarpal joints may also be required to aid in stability. Sometimes, rigid fixation is considered for these fracture patterns but may not always lead to desirable patient outcomes.
Overall, hamate fractures are quite rare and can be difficult to diagnosis, given the lack of experience of the radiologist and the intricate nature of the injury, and can lead to significant morbidity if not recognized and treated appropriately. Choosing the right treatment is the next critical step as full recovery depends on it. It has special relevance in sports medicine and lasting sequelae can severely compromise a sports career, making it all the more necessary to properly diagnose and treat it.