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
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.
In these circumstances a bone graft and screw may be required to secure bone healing.
4. Avascular Necrosis
The blood supply to the proximal part of the scaphoid is precarious (see diagram below) and fractures may rupture the arteries within the bone resulting in part of the bone dying. This 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. This is not a common occurrence.
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 recommended.
This means that the fracture has healed but in an abnormal shape (usually the bone crushes into itself ). If the fracture is displaced an operation is usually recommended to prevent malunion. If the fracture is mal-united it may cause premature wrist arthritis.
If the fracture is undisplaced and stable then it usually heals in plaster in 8-12 weeks. If it is unstable or displaced it may require immediate operation with bone graft taken from the pelvis and fixation of the fracture with a screw or wire. If the fracture doesn’t heal by 3 months it may require operation.