All You Need to Know About Hook of Hamate Fracture

The hamate bone is one of eight bones in the wrist that make up the carpal bones. Like any bone in the body, the carpal bones are at risk of fracture from a fall or other acute trauma. However, the hamate is a peculiar bone containing a triangular body and a projection called a hook. The hook is particularly prone to a fracture. So, what causes a hook of hamate fracture, and what do you do about it?

Fractures of the hook of the hamate make up only 2% of wrist fractures. However, these fractures are challenging to diagnose and difficult to heal.

Cause of hook of hamate fractures

The mechanism of injury of a hook of hamate fractures differs from other wrist fractures. Fractures often occur in people who do a sport involving gripping an object. Generally, these fractures are caused by hitting the ground with a golf club or swinging at a ball awkwardly with a baseball bat. So, golfers, baseball players, and hockey players make up the majority of people who suffer from this type of fracture.

However, sometimes, a hook of hamate fractures occurs from a direct force to the wrist or a fall onto an outstretched hand.

Diagnosis

After a hook of hamate fracture, sportspeople report the following symptoms:

pain at the fracture, which is in the outer part of the wrist below the distal wrist crease line

swelling and bruising in the wrist

grip weakness

Pins and needles in the palmar aspect of the ring and little finger, meaning that the ulnar nerve in the wrist is affected.

When examining someone with a possible fracture, you must check the function of the ulnar nerve. This nerve courses close to the hook of the hamate and can be damaged by a fracture, leading to weak grip strength. We call this condition Guyon’s canal syndrome.

Hook of hamate pull test

While palpation of the hook is the most sensitive sign of a fracture, the pull test is also helpful. In this test, we ask the person to move the ring and little fingers by flexing the tendons. This movement causes pain at the fracture site.

You need to be careful about imaging. Standard X-rays of the wrist can miss a hook of hamate fracture. A unique view, called the carpal tunnel view, can more easily detect a hook fracture. Other imaging, such as an MRI and a CT scan, is often used to confirm the diagnosis.

Treatment

$wrist cast fro hook of hamate fracture$

Hook of hamate fracture is difficult to treat as the blood supply to the hook is not ideal, leading to delayed healing or non-union.

Nonetheless, for an undisplaced hook of hamate fracture, we use cast immobilisation for 6-8 weeks. Generally, these fractures heal well with strict immobilisation, although there is a small risk of delayed union or non-union. After immobilisation, physiotherapy is needed to regain range of motion, strength, and movement control.

However, if the fracture is displaced, we recommend surgery to fix it with a specific type of screw internally. Evidence from studies suggests that post-surgical healing is excellent.

How to manage complications

Sometimes, fractures fail to heal, leading to chronic pain and reduced grip strength. Studies suggest that delayed union and non-union occur in about 50% of cases. In these cases, we recommend removing the hook. Often, the ulnar nerve near the hook is also released. Generally, complete excision leads to excellent outcomes after eight weeks. However, there are risks with this type of surgery, including nerve injury, infections, and reduced grip strength.

Also, ulnar nerve irritation occurs in about 20% of cases and is treated by removing the hook.

Final word from sportdoctorlondon about hook of hamate fracture

Hook of hamate fractures are rare but occur primarily in people who grip objects with their hands. Generally, people report pain and reduced grip strength at the outer part of the wrist and hand. We recommend cast-immobilisation for 6-8 weeks, although about 50% can be challenging to heal.