Reproduced with permission from Dr Stuart Myers at www.myhand.com.au
The scaphoid is the most important carpal (wrist) bone. It is a very important stabiliser of the mid carpal joint. It is also the most commonly injured wrist bone.
The Problem Bone
Scaphoid fractures can be difficult to treat for a variety of reasons.
1. Delay in Diagnosis:
- The first x-ray taken may be normal and the fracture may only become apparent on x-rays taken 10 - 14 days after the injury.
Because of this we treat the wrist as if it is broken until we can absolutely confirm that there is no fracture
- A Bone Scan taken about 3 days after the injury will confirm a fracture if it is present
2. Delayed Union (Delay in Healing):
- Fractures often taken 8 - 12 weeks to heal ( or even longer!) and require treatment for longer than other wrist injuries
- This is because the blood supply to the scaphoid is relatively tenuous
- The bone fails to heal despite adequate plaster treatment for 3 months
- More likely if the onset of treatment is delayed
- With longstanding fracture non-unions, cysts form
at the fracture site & the bone in this area resorbs
For this reason bone graft is needed to fill the resultant defect in this situation
4. Avascular necrosis:
- The blood supply to the proximal part of the scaphoid is precarious (see diagram) and fractures may rupture the arteries within the bone resulting in part of the bone dying. This may resolve spontaneously or may result in the bone softening and then collapsing years later
This can lead to irregularity of the joint surface and late onset wrist arthritis. Significant collapse is uncommon.
Sometimes the x-ray suggests the fracture has united but this may not be the case.
Therefore the wrist may require repeated x-rays for up to 12 months.
If there is any doubt about fracture healing a CT scan is often recommended.
When the Scaphoid fractures it tends to crush into itself. With the crushing the normal bean shape of
the Scaphoid is converted to an L shape.
A Mal-union means that the fracture has healed but in an abnormal shape.
In order to regain the normal shape the defect in the bone needs to be filled with bone graft removed
from the pelvis through a small incision. It is shaped accurately at the operation to fit the gap.
7. Wrist Arthritis
If the fracture is displaced an operation is usually recommended to prevent malunion.
1. Plaster - 8 - 12 weeks
2. Screw - Unstable or displaced fractures
- Allows early wrist movement ie no cast
- Rest in wrist brace
- Increases rate of healing
- Can be performed through a 10mm incision
3. Screw + Bone graft
- Crushing at fracture site
Bone graft is taken from the pelvis to fill defects in the scaphoid. Involves admission to hospital overnight. The fracture site is identified and any remaining scar tissue removed. The fracture ends are cut to smooth surfaces and the resultant defect measured. Bone is then harvested from the pelvis and shaped accurately to fill the gap.
The fracture is then stabilised with a screw &/or wires.
The position of the fracture is checked on an X-ray machine in the operating room.
Drains may be inserted in the wounds and removed after 24 hours.
A half plaster is then applied.
After the Operation
- If the fracture is stable the wrist can be gently moved immediately and rested in a splint for comfort
- If the fracture is unstable or there is concern about fracture healing then a plaster is worn until the fracture heals
- The time for fracture healing is very variable. In general it takes between 8 - 12 weeks
- The sutures in the hip are buried and will dissolve
Complications of Bone grafts to the Scaphoid:
- Non-union: The major problem is that the fracture fails to heal. This occurs in approx 5% of cases
- Swelling: The other concern after any hand surgery is excessive swelling resulting in the dressings or plaster becoming too tight. In general if the plaster feels too tight it is
- Other: Please read the handout sheet on Hand Surgery prior to coming into Hospital