The scaphoid bone is one of the most important carpal bones. It connects the hand to the forearm and builds a part of the wrist joint. The scaphoid lies on the thumb side of the wrist at an angle between the other carpal bones and the radius. Due to its exposed position and its high mobility, the scaphoid is the carpal bone that breaks the most. A typical accident scenario causing a scaphoid break involves falling on outstretched hands, which is often the case in many movements in certain sports.
After the fall, the patient sometimes complains of swelling on the wrist and indicates pains on the thumb side of the wrist, which intensify under stress. Occasionally the fracture goes unnoticed. This is usually because, firstly, the symptoms that a scaphoid break causes are often not distinctive, and secondly, a standard x-ray of the wrist does not show the scaphoid adequately enough. If a scaphoid break goes unrecognised, there are considerable risks due to the extremely slow healing of the fracture and a generally poor blood supply to the scaphoid which can cause development of a so-called scaphoid pseudoarthrosis.
Scaphoid pseudoarthrosis concerns a type of “false joint” which brings about permanent discomfort in the wrist joint. For this reason, after the corresponding trauma and with reason to suspect a fracture, further x-ray examinations should be carried out (using the Stecher method; x-raying the wrist in maximum ulnar adduction). An exact imaging of the fracture is required, namely to ensure that adequate therapy is introduced. Should there be no clear conclusions drawn then computer tomography should be conducted along the longitudinal axis of the scaphoid in order to prove or rule out a fracture and to clarify the cause of the instability. Additionally, it can be simultaneously ascertained whether the break is stable or displaced and therefore unstable. An MRI scan of the wrist joint for diagnostic purposes is less helpful, however, it is fundamental if questioning whether there is ligament injury or not.
Scaphoid fractures in which the fractured parts have not displaced are so-called stable fractures. However, despite the name, these can only be treated by immobilisation through the wearing of a plaster cast for 12 weeks. In order to shorten this lengthy treatment time, it is also possible to surgically treat a stable scaphoid fracture. This uses a minimally invasive operative technique requiring only very small incisions through which titanium screws are inserted into the scaphoid to stabilise it.
Unfortunately the most scaphoid bone breaks are unstable. Unstable fractures have either displaced bones, are near the wrist joint or are fragmented. It is necessary to treat these fractures using an open surgical technique because the breaks must be optimally reset, which means exactly back-to-back. The operative access site is, depending on the position of the break, either chosen on the front or back side. Stabilisation then follows with a titanium screw (“Herbert screw”), which can normally remain in the bone, but can be removed in exceptional cases.
A scaphoid break can lead to scaphoid pseudoarthrosis and wrist osteoarthritis.
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