SCAPHOID FRACTURES
What is the scaphoid?
In the wrist, there are eight small bones known as the carpal bones. They are arranged in two rows, one on top of the other.
The row that is closest to the long forearm bones (the radius and ulnar) is called the proximal row.
In the proximal row are the scaphoid (on the thumb side of the wrist), lunate, triquetrum and pisiform bones.
The second row (distal row) is formed with hamate, capitate, trapezoid and trapezium bones.
The scaphoid bone is one of the largest of the carpal bones and looks a bit like a cashew nut and is roughly the same size. It is narrow in the middle, called the waist, and the two halves of scaphoid link the two rows of carpal bones together and actually helps to stabilise them.
Scaphoid fracture
The scaphoid bone is the most commonly fractured carpal bone. This is because of its size and vulnerable position between the carpal rows and the much larger long radius forearm bone that meets it in the wrist.
A Fall On to your Outstretched Hand, called a FOOSH, is the most common cause. That is, when your hand is stretched out in front of you during a fall and your wrist is bent backward. You will usually put your hands out in this position for protection if you fall forwards, fall off a bike, or off a ladder. Your body weight is transferred down through the radius and onto the small scaphoid resulting in it fracturing.
Sometimes a direct blow to the palm of your hand can cause a scaphoid fracture. Rarely, repeated 'stress' on the scaphoid bone can lead to a fracture. This can occur, for example, with kango hammers and using a shovel in hard ground.
A scaphoid fracture may be one of many fractures in the wrist at the same time and they will require very careful placement to set correctly.
Scaphoid fractures may be non-displaced (the fragments of the broken bone haven't moved out of position) or displaced (there is some movement of the bone fragments).
Diagnosis
A Doctor will usually suspect a scaphoid fracture by the mechanism of injury, such as a FOOSH injury. There is a spot near the thumb called the snuff box which would be very tender if the scaphoid is fractured.
2 out of every 10 scaphoid fractures do not show up on an X-ray because it can hide behind all the other carpal bones. A repeat X-ray can be performed after 10-14 days to confirm the original suspected diagnosis because at this stage of healing a scaphoid fracture is more visible on X-ray.
It is usual to wear a wrist support to protect the scaphoid bone if a fracture is suspected but not confirmed. This is because the scaphoid bone can have difficulty healing as it has a poor blood supply. As bone heals it is very delicate so it is best to support it and keep it stabilised as a precaution.
Complications
Common complications:
- Delayed union means the scaphoid bone has not completely healed even after wearing a splint for 4 months
- Non-union means the scaphoid bone has not healed at all, the bony fragments are still separate. Non-unions are more common after scaphoid fractures because the blood supply to the scaphoid bone is poor. Good blood supply to a bone is very important in fracture healing—since blood carries oxygen and nutrients to the site of the fracture to aid in healing.
Both delayed and non-union scaphoid fractures are more likely if treatment is delayed for some reason or if the person is a smoker or has another underlying condition such as diabetes. This is the main reason why it is important to treat scaphoid fracture promptly.
However, the exact position of the fracture in the scaphoid bone, whether the fracture is displaced or not, and whether or not there is avascular necrosis (see below) can also affect the healing of a scaphoid fracture.
If delayed or non-union occurs, various treatments may be suggested, including wearing a cast for a longer period or surgery to help join the bone fragments together. Surgery may involve a bone graft to help with fracture healing. This is a procedure where bone tissue is taken from another area of bone in the wrist and inserted into the fracture site.
Malunion
This occurs when the fragments of the scaphoid bone heal in an incorrect position - for example, at a slight angle. If this happens, it may affect the movement of the wrist and lead to pain and problems gripping and holding objects.
Malunion may be seen on an X-ray or scans of the scaphoid bone.
Surgery is usually needed to correct this complication. The scaphoid bone is re-broken, aligned correctly and a bone graft is used to correct the deformity and encourage healing.
Avascular necrosis
Most commonly, a fracture occurs at the narrowest part of the scaphoid (known as the waist). This is where the blood supply enters the scaphoid bone. So, there is a risk that if you have a fracture in this area, it can sometimes stop the blood supply to part of the scaphoid bone, leaving part of the bone without a blood supply.
This means that the scaphoid will not be able to heal properly and part of the scaphoid bone 'dies', collapses and breaks up. ('Avascular' refers to having no blood supply and 'necrosis' means death.)
If it occurs, avascular necrosis can be seen on an X-ray of the scaphoid bone some months after the initial injury. However, avascular necrosis does not occur with all fractures around the waist of the scaphoid.
Osteoarthritis
Osteoarthritis can develop some time after a scaphoid fracture in some people. It is more likely if there have been complications of non-union, malunion or avascular necrosis.
Treatment at Hand Kinetics
In most cases the scaphoid bone will heal after 6 weeks, or a little longer, in a splint which immobilises the wrist and base of the thumb.
It is important to have several x-rays to check on the healing bone and this may mean removing the splint.
Hand Kinetics can make you a customised splint that will be super comfortable to wear and can be adjusted as swelling goes down.
If necessary after wearing a splint for a couple of months an exercise programme designed to target the muscles surrounding the scaphoid bone can be designed.
Please note:
If you have had arm or hand surgery please telephone to discuss this before attending. It is always helpful to bring any x-ray reports you may have if you recently attended hospital for your hand or arm condition.
Hand Kinetics Telephone: 0044 28 417 72301
www.handkinetics.com
contactus@handkinetics.com
