Introduction
A scaphoid fracture is the fracture of one of the carpal bones, which topographically forms the ball of the hand. The healing of a scaphoid fracture is often difficult because this small bone is fed by a relatively poor blood supply. Thus, the scaphoid is not supplied from the middle of the body, but in this case with blood vessels coming from the direction of the fingers.
In addition, the blood vessels supplying the scaphoid itself do not form any connections, so that the rupture of a vessel automatically means that the corresponding part of the bone is undersupplied. Therefore, fractures in the distal two-thirds of the scaphoid near the fingers heal faster and better than those in the proximal third near the wrist. The healing of the scaphoid is therefore considered challenging, and is not always crowned with success.
Healing
A healing of the scaphoid fracture can be achieved with surgery or without surgery. How the fracture is treated depends on the type of fracture itself. Fractures in the distal two thirds can be treated conservatively.
The distal third is immobilized for about 6-8 weeks. The middle third should be immobilized for 10-12 weeks due to the poorer blood supply. After up to 3 months of immobilization, however, muscles are atrophied and tendons are usually shortened.
However, with the help of consistent physiotherapy and a little patience, these muscles will be regained after some time. In addition to the limited range of motion (which usually results directly from immobilising the muscles and joints and not from the fracture itself), other residual symptoms may remain after conservative treatment. These include swelling, numbness in arm and hand and/or increased sensitivity to the weather.
Surgery is always indicated for fractures of the proximal third. Such a scaphoid fracture should always be screwed down. For this purpose, the two fracture fragments are screwed together with a titanium screw.
The pressure that now acts on the fragments allows them to grow together more quickly, almost like gluing two pieces of wood together under pressure. The advantage of the operation is that the hand is stable again after only a few days, i.e. can be used freely. The muscles do not degenerate, the tendons do not shorten, and the screw can usually be left in the hand, which rules out further surgery.
The “Herbert screw” was developed especially for the treatment of scaphoid fractures with surgery. It is a screw that is completely sunk into the bone and exerts an optimal traction on the bone pieces due to the two threads at both ends. It is inserted through a small skin incision (approx.
1 cm long) on the inside of the wrist, below the ball of the hand. The incision usually heals easily, leaving a very thin, small scar. Following an operation, certain complaints can also occur.
Because nerves running in the forearm can be irritated during the operation, the affected areas may also feel tingling or numb. These symptoms then disappear completely within a few months, but ultimately in almost all cases, so that the wrist is just as fit for use as before the accident. From time to time, however, it can also happen that the healing process is rather unfavorable.
The risk of this is particularly high if a small piece of the bone has been blasted off, which cannot be supplied with sufficient blood and therefore the healing process is slowed down and made more difficult, or if a scaphoid fracture remains undetected for a long time and therefore remains untreated. Then in some cases a pseudarthrosis of the scaphoid develops. This means that the bone fragments do not grow back together properly.
This ultimately leads to symptoms similar to those of osteoarthritis. Bone rubs against bone, which causes pain for the patient and leads to limited mobility in the joint. In such a case, there is usually an indication for (further) surgical intervention to prevent the complaints from becoming chronic and the hand from being unable to be used properly.
Often, however, a scaphoid fracture is not detected, as it is usually relatively painless. It is possible that a slightly painful sensation remains in the palm of the hand for a few weeks or months, but this does not really bother and is therefore often ignored.Of course, not every bruise of the ball of the hand has to be caused by a scaphoid fracture, but these are often overlooked. Typically, a scaphoid fracture is also relatively difficult to detect on X-ray, which is why CT has established itself as the diagnostic tool of choice.
In the absence of treatment, there is a risk that the fracture fragments will grow on top of each other in a malaligned position. Since the eight carpal bones are in close physical relationship to each other, there is an altered force effect in the wrist. This can be imagined as if one bridge pier could suddenly carry less weight and distribute its load to the other bridge piers.
This can lead to the so-called “SNAC-Wrist Syndrome”, which is loosely translated as “Scaphoid Nonunion Advanced Collapse”. This syndrome can develop into pseudarhtrosis. In German, the term could best be translated as “Pseudo joint”, since the joint is still present, but does not function at all or only to a limited extent.
Pseudoarthrosis in the wrist area is problematic in that we use the hand daily for the simplest activities, and healing can only be achieved with surgery. For this purpose, a piece of bone is removed from the iliac crest and inserted into the fractured scaphoid. A wire is then drilled from the fingers to estimate the length of the required screw.
The individual bone fragments are threaded as centrally as possible on the screw, whereby care must always be taken to ensure an adequate blood supply. As the description of the operation already indicates, this is a relatively tricky procedure. However, it is relatively difficult to accelerate the healing process.
The bone needs time to grow together and the blood vessels must first find their way to the fractured bone fragments. To speed up the healing process, patients can take the greatest possible care and bring patience. Unfortunately, the scaphoid fracture is one of those fractures that take a long time to heal.
Even the best surgeon cannot change the anatomical conditions, so that at most only pain medication remains until the end of the therapy. In case of pain, the doctor usually prescribes commercially available painkillers such as ibuprofen or paracetamol, which are well tolerated by the patients.
