The hand consists of several differently shaped bones. The scaphoid bone is one of the eight carpal bones and is part of the wrist. The lower edge of the scaphoid bone forms the joint surface in the direction of the radius.
Strictly speaking, the human body has two different scaphoids:
- the scaphoid bone at the carpus and
- the navicular bone at the base of the foot.
However, the injury is much more common in the hand, so that it is equated with the term scaphoid fracture. Doctors also refer to it as a scaphoid fracture.
Anatomy of the left hand showing the scaphoid © bilderzwerg / Fotolia
A scaphoid fracture is the most common fracture injury to the carpus. Around 75% of all carpal fractures affect the scaphoid bone.
Athletes between the ages of 20 and 30 are particularly frequently affected by scaphoid fractures. Around 90% of these are men.
A fracture of the scaphoid bone in the hand is caused by strong and direct force.
When falling, people reflexively stretch their arms forward to avoid falling on their face. The force transmitted by the forearm on impact often results in a fracture of the scaphoid or radius.
The point at which the scaphoid breaks depends on
- the extent of the hyperextension and
- the movements of the hand during the impact.
Scaphoid fractures occur particularly frequently during sporting activities. Inline skating or snowboarding are considered typical high-risk sports because they often involve falls.
© yodiyim / Fotolia
The typical symptom of a scaphoid fracture is pain in the hand. This is particularly noticeable on the back of the hand and on the side of the thumb. The wrist also swells and is particularly painful when moving. The affected person often adopts a relieving posture as a result.
There is also increased sensitivity to pressure on the back of the hand, at the wrist crevice. This is where the two tendons responsible for spreading the thumb run. If pressure pain is described at this point, this is usually a clear sign of a scaphoid fracture. This is true even if the fracture is not clearly visible on the X-ray.
Most patients usually hold the affected hand close to their body so that it is not exposed to shocks. The patient finds it difficult to grip and suffers considerable pain.
A scaphoid fracture therefore often has a considerable impact on everyday life.
The first step in diagnosing a scaphoid fracture is a physical examination of the affected hand. The doctor will look at exactly where the pain occurs. He or she will also observe whether the patient adopts a protective posture with the hand.
One of the examination options is the Watson shift test. In this procedure, the patient's hand is moved towards the thumb. If there is a fracture of the scaphoid bone, a small click can be felt above the bone, followed by a sharp pain in the wrist.
Imaging procedures such as X-rays are important for making a diagnosis. However, a scaphoid fracture cannot always be detected on an X-ray. Fresh fractures are often even overlooked in the X-ray image.
If the diagnosis remains unclear after the X-ray, the doctor will carry out a computer tomography(CT) scan. A CT scan produces fine slice images of the wrist. This usually allows the fracture line to be recognized.
A scaphoid fracture is treated either conservatively or surgically. Which form of therapy is ultimately considered depends on the individual. The treatment depends on the location of the injury in the hand.
Conservative treatment usually takes longer. On the other hand, there are certain risks associated with surgery.
Conservative therapy: patience and rest
Aprerequisite for the success of conservative therapy is that the fracture fragments of the scaphoid have not displaced.
Treatment of the fracture then essentially consists of immobilizing the affected hand. It is given a plaster cast or plastic bandage.
After around two to three weeks, the doctor will take x-rays again to check the healing process.
However, the scaphoid fracture takes a certain amount of time to heal. Patients should expect to have to immobilize their hand for two to three months.
After this time, the treatment should be followed by physiotherapy.
Surgery
Surgical intervention is considered necessary if
- there are separate fracture fragments or
- the scaphoid fracture is in the immediate vicinity of the forearm joint surface.
The reason for this is the poor healing prospects for these two fracture variants.
During the operation, the surgeon reconnects the two fracture fragments using screws (Herbert and Bold screws).
Operation on a scaphoid fracture (left) with Herbert screws (right) © Hellerhoff | Wikimedia
Under certain circumstances, this procedure can be performed in a minimally invasive way. This has the advantage of a significantly shorter aftercare period.
Following the operation, the hand is placed in a plaster cast for around four weeks.
In principle, healing is faster after surgery than with conservative therapy. In most patients, the screw remains in the wrist for the rest of their lives.
How long it ultimately takes for the scaphoid fracture in the hand to heal depends on where the fracture occurred. Age also plays an important role. The younger the patient is, the faster the healing progresses.
However, it is not possible to make a general prognosis for the healing time due to the numerous decisive individual factors.
If the fracture is uncomplicated and the patient is young, the prognosis for scaphoid fractures is usually favorable. In some cases, however, there is a risk of pseudarthrosis, in which the fracture heals only incompletely.