Scaphoid Fractures:
The Wrist Break That Can Hide on X-Ray

What the scaphoid is

The wrist contains eight small carpal bones arranged in two rows. The scaphoid — named from the Greek for "boat" because of its curved shape — sits on the thumb side and bridges both rows, linking the forearm bone (radius) to the bones at the base of the hand. That bridging position makes it essential to normal wrist movement, and also makes it the carpal bone most likely to break: scaphoid fractures account for around 90% of all carpal fractures (Dias et al., Lancet, 2020). In Japanese it is called shūjōkotsu kossetsu (舟状骨骨折).

Two features make the scaphoid unusual. First, much of its surface is covered in joint cartilage, leaving limited room for blood vessels to enter. Second, its main blood supply enters toward the end nearest the thumb and flows backward to the end nearest the forearm (the proximal pole). A fracture across the bone can therefore cut off blood flow to the proximal fragment, which is one reason these fractures can be slow to heal, fail to heal (nonunion), or lead to loss of blood supply to part of the bone (avascular necrosis).

Who gets it and how

The classic mechanism is a fall onto an outstretched hand with the wrist bent backward. In a population study from Edinburgh, the annual incidence of confirmed scaphoid fractures was 29 per 100,000 adults; about 70% occurred in men, who were also significantly younger than the women affected. Simple falls from standing height were the most common cause, while men were more likely to be injured in higher-energy events such as sport or road accidents (Duckworth et al., Journal of Trauma and Acute Care Surgery, 2012). In Tokyo, cycling falls, skiing and snowboarding trips, ball sports and slips on wet stairs are familiar scenarios.

Fractures are described by location — the distal pole (nearest the thumb), the waist (the middle, and the most common site), and the proximal pole — and by whether the fragments have shifted (displaced) or remain aligned. Location and displacement are the two features that most influence treatment.

Symptoms

Typical symptoms are pain and swelling on the thumb side of the wrist, pain when gripping or pinching, and pain on moving the wrist or thumb. Many people can still move the wrist reasonably well, and visible deformity is unusual, which is why a scaphoid fracture is easily dismissed as a sprain. A doctor will usually press over the anatomical snuffbox (the small hollow at the base of the thumb when it is extended), over the bony prominence on the palm side of the wrist, and push along the thumb toward the wrist; tenderness at these points raises suspicion. None of these signs is definitive on its own, but together with the history they guide imaging.

Why diagnosis can be difficult

Standard wrist X-rays, including special scaphoid views, are the first test. The problem is that a fresh, undisplaced crack may not be visible for days or even weeks. At the same time, most people with a suspected scaphoid fracture do not actually have one. Doctors must balance two risks: missing a real fracture, which may then heal poorly, and immobilising many uninjured wrists "just in case".

Traditionally, a suspected fracture with normal X-rays was treated in a splint or cast with repeat X-rays after 10–14 days. Increasingly, advanced imaging is used earlier to reach a definite answer sooner.

Test	What it shows	Limitations
X-ray	Visible fractures, displacement, alignment of the carpal bones	Can miss fresh undisplaced fractures
MRI	Bone bruising and fracture lines not seen on X-ray; soft-tissue and ligament injury	Availability, cost and scan time; some false positives
CT	Fine bony detail — displacement, fracture pattern, and later whether the bone has healed	Less sensitive than MRI for subtle fresh fractures; radiation dose
Bone scan	Increased bone activity at a fracture site	Usually needs 72 hours after injury; less specific; radiation; now used less often

Even MRI has limits when the chance of a true fracture is low: a review noted that false-positive scans occur and that the best strategy may combine imaging with clinical prediction rules based on the patient's age, sex, mechanism of injury and examination findings (Duckworth et al., Journal of Bone and Joint Surgery British Volume, 2011). In Japan, MRI and CT are widely available, and early cross-sectional imaging is commonly used when the clinical picture is suggestive.

Treatment options

Treatment depends mainly on where the fracture is, whether it is displaced, how long ago it happened, and the person's work and activity demands.

Cast or splint immobilisation

Most undisplaced or minimally displaced fractures of the distal pole and waist are treated in a below-elbow cast. Distal pole fractures usually heal relatively quickly; waist fractures commonly need several weeks of immobilisation, with healing checked by X-ray or CT before the cast is removed. Whether the thumb needs to be included in the cast has been debated.

Surgical fixation

Surgery usually involves passing a small compression screw across the fracture, often through a short incision or percutaneously (through the skin) under X-ray guidance. It is generally recommended for displaced fractures, many proximal pole fractures (which have a higher risk of not healing), fractures associated with other wrist injuries, and established nonunions. For undisplaced waist fractures, early surgery was once promoted as a way to return to work and sport faster, and its use grew — which led to a large trial to test it.

SWIFFT result	Early surgery	Cast first
Wrist score (PRWE) at 1 year*	11.9	14.0 (no significant difference)
Potentially serious surgical complications	14%	1%
Cast-related complications	2%	18%
Nonunion on imaging at 5 years	2.1%	3.3%

*Patient-Rated Wrist Evaluation, 0–100; lower scores mean less pain and disability.

These findings apply to waist fractures with little or no displacement. Treatment of displaced fractures, proximal pole fractures and injuries in elite athletes or people with special occupational demands is more individualised, and the trade-offs — time in a cast versus the risks of an operation — are worth discussing openly with a hand surgeon.

When things don't heal

Timely immobilisation matters. In a Danish series of 285 scaphoid fractures, a delay of less than four weeks before immobilisation did not increase healing problems, but when the delay exceeded four weeks, most fractures had healing complications (Langhoff and Andersen, Journal of Hand Surgery British Volume, 1988). An untreated nonunion is not always painful at first, but over years it can change the mechanics of the wrist. In a classic study of 47 symptomatic nonunions followed for between 5 and 53 years, degenerative changes progressed from changes confined to the scaphoid to arthritis between the scaphoid and radius and, eventually, more generalised wrist arthritis; few nonunions remained free of arthritis after ten years (Mack et al., Journal of Bone and Joint Surgery American Volume, 1984). This pattern is sometimes called scaphoid nonunion advanced collapse (SNAC).

Nonunions are usually treated surgically, often with bone grafting and screw fixation; later-stage arthritis may require salvage procedures. Outcomes are generally better when nonunion is recognised early, which is why follow-up imaging until the bone has clearly healed is an important part of care.

Recovery

After the cast comes off or surgery heals, stiffness and weakness are common and usually improve with a graded programme of range-of-motion and grip-strengthening exercises, sometimes guided by a hand therapist. Return to desk work can often be early; heavy manual work, contact sports and activities that load the wrist in extension (push-ups, gymnastics, yoga weight-bearing poses) generally wait until healing is confirmed. Smoking is widely regarded as a risk factor for poor bone healing, and stopping is advisable.

When to see a doctor

After a fall onto the hand, wrist pain on the thumb side that persists beyond a day or two — particularly with tenderness at the base of the thumb or pain on gripping — is worth having examined, even if you can still move the wrist. If the first X-ray is normal but pain continues, ask about follow-up imaging rather than assuming it is a sprain. An old wrist injury that "never quite settled", with ongoing ache or reduced movement, can also be a reason to check for an unhealed scaphoid. In Tokyo, an orthopaedic hand surgery clinic (手外科) is usually the most appropriate first contact; many general orthopaedic clinics can perform the initial X-rays and refer on if needed.