What is the Hamate Bone?
The hamate bone is one of eight bones in the wrist known as the carpal bones. It is sometimes referred to as the unciform bone. Unciform means hook-shaped, and the hamate has a hook-like section protruding from the main, triangle-shaped bone which is known as the body. The hook sticks up into the palm, where it is sometimes injured, either as the result of a fall or during sports such as golf or tennis, where a club or racket is gripped and swung in a way that can place stress on the bone and cause a fracture. Hamate fractures may be treated using a cast, but surgery may be needed in more complex cases.
Inside the wrist, the carpal bones form two rows, with the hamate bone being located in the row further away from the forearm and closer to the bones of the fingers. Each carpal bone is attached to its neighbors by strong strips of tissue called ligaments. Although the hamate is not a frequently damaged wrist bone, hamate fractures are becoming more common as sports involving clubs, bats and racquets increase in popularity.
Two different types of fractures may affect the hamate bone. In the first type, the hook breaks away from the body of the bone, perhaps following repeated use of a bat or racket, or as the result of a direct blow during a fall or a single, forceful swing of a golf club. With the second type of hamate fracture, the body of the hamate is broken, and this can follow a direct blow or crushing injury involving the wrist. Symptoms of a broken hamate bone include pain, a weak grip, and if the ulnar nerve, which runs nearby, is also damaged, the fourth and fifth fingers may tingle and feel numb. Sometimes, ligaments and muscle tendons rub against the fractured bone causing possible fraying, and even tearing, if the injury is not treated.
Hamate bone fractures can be difficult to diagnose on an X-ray, as the wrist bone may be hidden by its neighbors. A CT, or computerized tomography, scan is sometimes used to obtain a better image of the injured hamate. When a fracture involving the hook of the hamate is treated early, simply immobilizing the arm in a cast may be enough to allow the bone to heal. Sometimes, especially if a person does not seek treatment straight away, there is a risk that part of the hamate bone could die off and the hook might have to be removed. While hook removal is the more commonly performed operation, an alternative procedure exists which involves opening up the wrist and fixing the hamate bone together with screws.
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