Scaphoid fractures of the wrist are common injuries. They are caused by a fall on the hand when the force of the fall causes the Scaphoid bone to break. Scaphoid is one of the eight bones forming the wrist joint. It is a small curved bone and therefore the fracture is difficult to see on x-rays. Diagnosis is therefore difficult unless a scan is done. Most patients are treated because a scaphoid fracture is suspected after clinical examination even though it is not confirmed on x-rays. Some of the patients in this group turn out not to have a fracture and after a few weeks the treatment is discontinued. This means that some patients have to undergo plaster treatment which they did not in reality need. If MRI or CT scan is readily available then an exact diagnosis is possible at the start.
Another curious problem specific to Scaphoid bone is that it has a poor blood supply mainly because it is largely surrounded by a layer of articular cartilage and blood vessels cannot enter the bone expect through a very small area. This means that failure of fracture healing (non-union) is common even with appropriate treatment.
Injury and Symptoms
The fracture is caused after a fall on the outstretched hand. There is not much swelling or bruising but pain is severe especially on the thumb side of the wrist. Movements are restricted because of pain.
Examination by the orthopaedic surgeon reveals tenderness on the Scaphoid bone. The Scaphoid series x-rays are done to look at the Scaphoid bone from different angles. Fracture is commonly through the waist of scaphoid.
After clinical examination, helped by x-rays, a diagnosis is made and treatment is started. Most Scaphoid fractures are initially treated in Plaster casts. The plaster holds the wrist and thumb immobilised. Plasters are checked regularly and x-rays are repeated. If the fracture is not confirmed in the subsequent visits then treatment is discontinued. If a fracture is confirmed then plaster is continued for a period of 8 weeks.
Surgical treatment is sometimes recommended if fracture is unstable or displaced. Even stable fractures can be treated by operation if patients do not want to be in plaster for 8 weeks because of their work or sport commitments. Operative treatment means fixation of the fracture using a bone screw. The operation is often done through a 1 cm incision on the front or back of the wrist. If fracture is displaced then a small incision measuring 5cm is necessary.
When the treatment is progressing well and there are signs of fracture healing, the plaster cast is removed after 8 weeks. Physiotherapy is usually required to regain movements and strength. After surgical treatment plaster may be required for a short period followed by physiotherapy.
Non-Union (failure of fracture healing)
Around 10% of stable Scaphoid fractures fail to heal. Non-union rate is higher in unstable and displaced fractures and when no treatment was sought or it was delayed. Some non-unions are associated with avascular necrosis (AVN) which means that one half of the broken scaphoid is dead because of lack of blood supply. This is evident on x-rays and MRI scans.
In non-unions, the wrist is painful particularly after activity. The pain generally is not too severe and most patients are able to work. This state may continue for many years but if left untreated wrist may develop arthritis after some years. Some patients never see a doctor thinking that the injury was simple sprain and even when the wrist continues to ache now and then they do not have the wrist checked. Only after 5 - 10 years once they start getting increasing pain from arthritis that they see a doctor and to their surprise the x-rays then confirm that all along they had a fracture which failed to heal leading to arthritis.
Treatment of Non-Union
Treatment of non-union depends on a number of factors. From your point of view, the reason for having further treatment is continuing pain and disability. The operation when successful also prevents arthritis later in life. Once the diagnosis of non-union is confirmed, the surgeon will discuss further operation and the success rate. Success of the operation depends on the time passed from fracture. If the non-union is more than 5 years old, success of operation is low. Presence of AVN (see above) also substantially reduces the success of the operation. If arthritis has already started then you may require a different type of operation.
The standard operation for a non-union which is less than 5 years old is bone graft and screw fixation of the fracture. The operation is done under Regional or General Anaesthesia as a day case. You may require a plaster for a period of 4 to 6 weeks. Bone graft is usually taken from the radius (forearm) through the same incision.
If non-union is longer than 5 years old or if early arthritis appears to have set in then an Arthroscopy of the wrist may be necessary if only to establish the extent of arthritis and at the same time carry out excision of radial styloid to help arthritic pain.
If arthritis is already advanced then the only operation which will be suitable is partial fusion (SLAC operation) or total wrist fusion.
Your surgeon will discuss all these options including the risks and success rates to enable you to make a decision.
FRCS (Trauma & Orth)
Consultant Trauma and Hand Surgeon