Hamate fractures are uncommon injuries, representing only 2% of all wrist fractures. The break is often sustained by athletes who play sports where some type of object is swung or wielded, such as a stick or club that causes a direct blow to the hamate bone (Fig. 1). A golfer, for example, can fracture the hamate when hitting the ground during a golf swing. Golfers are not the only athletes at risk, however, baseball, hockey, racquetball, and tennis players are also known to injure the hamate bone. It rarely occurs, but a fall onto the palm can result in a hamate fracture, as well.
One of 8 carpal bones, the hamate is found in the hand, close to the wrist and below the ring and small finger (Fig. 2). The bone is triangular shaped and has a small hook-like bony projection on the palm side called the hook of the hamate. A fracture to the bone is either diagnosed as a fracture of the hamate body or to the hook. The hamate bone articulates (connects loosely to allow motion) with 5 other bones—2 in the hand and 3 in the wrist. The hook of the hamate also serves as the site of attachment for ligaments and it forms part of the Guyon, or ulnar canal. The ulnar nerve and the ulnar artery pass through the Guyon canal very close to the hamate, which explains some of the symptoms a patient may develop after a fracture.
Symptoms and diagnosis
A hamate fracture can be diagnosed with a physical exam and x-rays. Often, the patient will touch the area over the hamate to describe the location of the pain or complain of pain in the palm while holding an object. The physician may confirm the site by applying pressure over the area to see if it is sensitive or elicits pain. The physician may also use a resistance test since the hook of the hamate acts as a pulley for 2 of the fingers. To complete the test, the doctor places his or her fingers against the patient’s small and ring fingers while the patient
tries to resist the hold. If the resistance produces pain similar to what occurred during injury, there is a good chance that the hook of the hamate has been fractured. Other symptoms of a hamate fracture include decreased wrist strength and sometimes numbness or tingling in the ring and small fingers because the ulnar nerve that supplies both muscle stimulation and sensation is being compressed. If a fracture is suspected, the physician will order x-rays to capture the image of the hamate body and the hook that might otherwise not be visible. An x-ray image can confirm the fracture; however, there are occasional difficult cases that require more advanced imaging, such as a computerized tomography (CT) scan.
Treatment for fractures of the hamate body and hook vary slightly and fortunately, both types can often be treated without surgery. Nondisplaced fractures (the bones remain in place) can be successfully treated by immobilizing the wrist with either a removable brace or a fiberglass cast. If the patient has swelling a splint may be chosen instead. After 6 to 8 weeks of immobilization the fracture usually heals and activity can be resumed. If the injury is a displaced fracture (the bone fragments have moved out of alignment) treatment can be more difficult to manage and often requires surgery.
An untreated hook fracture can result in nonunion (the fracture fails to heal) if the ulnar artery is injured or pinched causing a poor blood supply to the bone and increasing the risk of osteonecrosis (death of the bone tissue). Additionally, without immobilization, the constant pull exerted on the hook fragment by finger movement does not give the bone time to heal. When nonunion occurs, the hook portion of
the bone can be removed. Athletes sometimes choose this type of surgery because they can return to sport earlier. With displaced hamate fractures, the surgeon often performs an open reduction (moving the bone back in the anatomic position) and uses internal fixation, such as a screw or pin.
After surgery, the incision may be tender and hand weakness can affect grip strength. This will improve as the incision heals and rehabilitation begins. Physical therapy with a certified hand therapist can begin 10 to 14 days after surgery.
Early treatment means better outcomes
A common problem with hamate fractures is that an injured patient often believes the injury is not serious and that it will heal on its own; and, therefore, doesn’t seek medical attention right away. When the pain continues or recurs after rest the patient seeks help, but with the time that has passed the fracture can fail to heal on its own. Then surgical intervention is needed. Hamate fractures that are treated soon after injury have excellent outcomes, especially when early treatment is followed by a rehabilitation program. Delaying treatment, however, can lead to complications that cause unnecessary pain and inconvenience for the patient.
Author: Darren E. Barton, DO
Reprinted with permission from the Hughston Health Alert, Volume 29, Number 3, Summer 2017.