The scaphoid is ‘boat’-shaped* bone and is the most common carpus to be fractured.
Scaphoid fractures are most common in men aged 20-30 years and are high-energy injuries. Approximately 10% have an associated fracture.
They are very commonly referred to orthopaedics, due to diagnostic uncertainty; however, only around 1 in 10 referred patients actually have a scaphoid fracture.
*The word scaphoid derived from the Greek word “skaphos”, which means boat
The scaphoid is anatomically divided into three parts: the proximal pole, waist, and distal pole.
It is important to appreciate the blood supply to the scaphoid (Fig. 2), which is by branches of the radial artery. The dorsal branch of the radial artery, which supplies 80% of the blood, enters in the distal pole and travels in a retrograde fashion towards the proximal pole.
Consequently, fractures can compromise the blood supply, leading to avascular necrosis (AVN) and subsequent degenerative wrist disease. The more proximal the scaphoid fracture, the higher the risk of AVN.
The scaphoid is fractured following trauma, which is often high energy. Patients will complain of sudden onset wrist pain and bruising may be present.
There is tenderness in the floor of the anatomical snuffbox, pain on palpating the scaphoid tubercle, and pain on telescoping of the thumb.
The Anatomical Snuffbox
The anatomical snuffbox (also termed the radial fossa) is a triangular depression found on the lateral aspect of the dorsum of the hand, located at the level of the carpal bones. It is defined laterally by the abductor pollicis longus and extensor pollicis brevis tendons (the 1st extensor compartment), and medially by the extensor pollicis longus tendon (the 3rd extensor compartment).
The contents of the snuffbox includes the radial artery, superficial radial nerve, and the cephalic vein. The floor of the snuffbox is made of the scaphoid, along with the trapezium (distally) and the radial styloid (proximally); tenderness in this area may indicate a scaphoid fracture, but this is not specific.
The main differentials of radial wrist pain following trauma are distal radial fracture, an alternative carpal bone fracture, fracture of the base of the 1st metacarpal, ulnar collateral ligament injury, wrist sprain, or De Quervains tenosynovitis.
For suspected cases of scaphoid fracture, initial plain radiographs should be taken. A “scaphoid series” should be requested, including anteroposterior, lateral, oblique views.
Scaphoid fractures are not always detected by initial radiographs (especially undisplaced fractures); if there remains sufficient clinical suspicion, despite negative initial imaging, the patient should have the wrist immobilised in a thumb splint and repeat plain radiographs in 10-14 days for further evaluation (Fig. 3).
If repeat radiographic imaging is negative, however clinical findings are still in keeping with a scaphoid fracture, an MRI scan of the wrist is indicated. This is the definitive investigation and, whilst it is awaited, the interim management is as for a fracture.
The treatment of scaphoid fractures is determined by location of the fracture and degree of the fracture.
Undisplaced fractures can typically be managed with strict immobilitasion in a plaster with a thumb spica splint. However, undisplaced fractures of the proximal pole have a high risk of AVN and surgical treatment may be advocated, particularly if it is the dominant hand of a working-age patient.
All displaced fractures should be fixed operatively. The most common operative technique is using a percutaneous variable-pitched screw, which can be placed across the fracture site to compress it.
Avascular necrosis is common complication of a scaphoid fracture (in around 30% of cases), with its risk increasing the more proximal the fracture.
Non-union is the bone failing to heal properly, most commonly due to a poor blood supply. It is particularly common in scaphoid fractures (in around 10% of cases) that go undiagnosed or are inappropriately managed. Such cases can be managed with internal fixation and bone grafts, although the morbidity is high, even with surgical repair.
- The scaphoid is the most commonly fractured carpal bone, often occurring through falling on an outstretched hand
- Diagnosis is based on history, clinical examination, and imaging
- If initial radiographs do not show evidence of a fracture however there is sufficient clinical suspicion, treat conservatively and re-image in two weeks
- Important complications of scaphoid fractures are avascular necrosis and non-union