It is the fracture that hides behind a wrist sprain. A young man falls on his hand, a radiograph is taken, nothing is seen, the word sprain is used and he is sent home with a soft splint. In a considerable proportion of these patients the fracture is indeed there: it simply cannot be seen yet. The scaphoid receives its blood supply against the current, from the bottom upwards, which makes its proximal pole dependent on a fracture line that has just cut off its supply. It is the only common fracture in which the main risk factor for nonunion is not the violence of the impact, but the time taken to recognise it.

Summary written from primary sources verified one by one on PubMed through the E-utilities interface: identifier resolved, journal, year and author list checked, abstract read before citation. Full bibliography at the end of the article.

Clinical summary

Scaphoid fracture is not missed because it is rare or misleading. It is missed because a normal radiograph is falsely reassuring, and because the word “sprain” closes the file.

Why the scaphoid breaks, and why it unites badly

A bone that bridges the two rows of the carpus, and that receives its blood against the current: two anatomical peculiarities, two clinical consequences.

A hinge bone, and therefore exposed

The scaphoid is the most lateral bone of the proximal row of the carpus. Its elongated, oblique shape carries it across the midcarpal joint line: it is the only bone that articulates with both rows, which makes it the mechanical link of the carpus. Three parts are described: the distal pole (or tubercle), the waist or middle third, and the proximal pole.

That hinge position explains its exposure. In a fall on the hand in hyperextension, the load concentrates at the junction of the two rows, precisely where the scaphoid crosses the joint line. That is why the waist accounts for most fracture lines: Jørgsholm's systematic review finds 60 to 69 % of fractures at the waist1.

A blood supply that runs upwards, and that one fracture line is enough to cut

The decisive peculiarity is vascular. The main arterial supply to the scaphoid enters through its distal and dorsal part, then runs inside the bone towards the proximal pole. That supply is described as retrograde : it flows against what anatomy would lead you to expect. The proximal pole has no significant arterial entry of its own; it depends entirely on that flow coming up from below.

The consequence is mechanically unavoidable. A fracture line at the waist, and all the more so at the proximal pole, interrupts the supply to the fragment lying upstream. The more proximal the line, the larger the devascularised fragment, and the slower and more uncertain union becomes. That is what sets this fracture apart from almost all others: it is not only the bone that is broken, it is also its supply line.

Buijze's review of scaphoid nonunion lists the risk factors in this order: displacement and instability first, then a delayed or missed diagnosis, an inadequate treatment, the site of the fracture line and the blood supply12. Three of those five factors depend on what the health system does, or fails to do, in the first few weeks.

Who fractures their scaphoid, and how?

The typical profile is useful because it guides the pre-test probability, and therefore the decision about imaging.

A young man, in the great majority

Duckworth's prospective Scottish study, which recorded over one year every radiographically confirmed scaphoid fracture in a defined adult population, finds 151 fractures and an annual incidence of 29 per 100,000 (95 % CI 25 to 34). The male predominance is clear (105 men out of 151, p < 0.001), and the median age of men is significantly younger than that of women (p = 0.002)2.

Jørgsholm's systematic review, covering 42 studies, sets out the age distribution: in men, the peak lies between 20 and 29 years, with reported incidences of 107 to 151 per 100,000 men; in women, the peak is earlier, between 10 and 19 years, with incidences of 14 to 46 per 100,0001. In children, the fracture mainly affects boys aged 12 and over, and remains rare before the age of 9.

The gap between Duckworth's overall incidence (29 per 100,000) and Jørgsholm's figures comes from the reference population: the first covers all adults, the second age and sex bands in which the risk concentrates. Both are consistent, and Jørgsholm in fact concludes that there is considerable heterogeneity between studies and that the epidemiological level of evidence is overall low1.

Two mechanisms, two severity profiles

Duckworth adds a distinction useful for clinical reasoning. Low-energy falls from standing height accounted for 40.4 % of mechanisms, but men were significantly more likely to fracture in a high-energy injury (p < 0.001). The most frequent Herbert classification was type B2 (55 cases, 36.4 %), and above all, unstable fractures were more frequent in younger patients (p = 0.025) and after a high-energy injury (p = 0.042)2.

Why the initial radiograph does not settle it

This is the heart of the subject, and the reason this fracture is nicknamed the wrist sprain trap.

What the figure really means

The widespread claim that “one scaphoid fracture in four cannot be seen on the initial radiograph” circulates a great deal, and it needs rewording to be accurate.

What Carpenter's meta-analysis establishes, from 75 studies included out of 957 citations examined, is a pre-test probability : in adult emergency department patients with clinical concern about a scaphoid injury and a non-diagnostic initial radiograph, the prevalence of fracture found on subsequent imaging ranged from 12 % to 57 %, with a point estimate of 25 %3. In other words, the figure describes the proportion of true fractures among suspected patients with a normal radiograph, and not the proportion of scaphoid fractures that escape radiography.

Two other pieces of work measure the same quantity and give lower values, which is worth saying rather than keeping the most striking figure:

• Coventry's systematic review, across 8 studies and 1,685 injured wrists, finds a prevalence of scaphoid fracture despite normal radiographs of 9.0 %5.
• The Cochrane imaging review gives a median prevalence of true fractures among suspected cases of 20 %6.

These gaps are not contradictions: they reflect different populations and different thresholds of suspicion. A department that radiographs widely will have a low prevalence; one that suspects only on clear signs will have a high one. The clinical conclusion is the same in all three cases, and it is robust: a normal radiograph does not allow the fracture to be ruled out, and Carpenter states it plainly from the outset.

Which clinical signs are actually worth something?

Many tests, little specificity, and a single sign that genuinely helps rule the diagnosis out.

The anatomical snuffbox: very sensitive, not very specific

Mallee's meta-analysis identified 13 studies describing 25 clinical tests, including only studies carried out before radiographic assessment and with an acceptable reference standard. Two tests had enough data for statistical analysis:

• Tenderness on palpation of the anatomical snuffbox (8 studies, 1,164 patients): sensitivity of 0.87 - 1.00, specificity of 0.03 - 0.98.
• Longitudinal compression of the thumb (8 studies, 961 patients): sensitivity of 0.48 - 1.00, specificity of 0.22 - 0.97.

Heterogeneity was such that the authors gave up on calculating pooled estimates. Two other tests had high sensitivity: scaphoid tubercle tenderness (sensitivity 0.82 to 1.00; specificity 0.17 to 0.57) and pain on ulnar deviation (0.67 to 1.00; 0.17 to 0.60). Above all, three studies showed that combining tests increased specificity and post-test probability while keeping sensitivity high4.

What a more recent review adds

Coventry's systematic review, focused on patients with normal radiographs, assessed which signs best predict an occult fracture. Its results deserve careful reading, because they point to tests that are not much used:

The best-performing test, pain on resisted supination, reaches remarkable values, but its very wide confidence interval (6.5 to 312.5) betrays a limited sample. The authors say so explicitly: this sign would need external validation before being widely adopted. And their general conclusion is unambiguous: no single sign satisfactorily rules out an occult scaphoid fracture5.

That conclusion meets Carpenter's, put differently: apart from the absence of anatomical snuffbox tenderness, which significantly lowers the probability of fracture with a negative likelihood ratio of 0.15, history and physical examination alone are insufficient to confirm or rule out the diagnosis, and no validated clinical decision rule exists3.

Which imaging when the radiograph is normal?

Three possible investigations, three very different error profiles, and a trade-off that depends on what you fear most.

What the Cochrane review measured

Mallee's Cochrane review compared CT, MRI and bone scintigraphy in suspected patients with normal radiographs. Eleven studies were included: 4 for CT (277 suspected cases), 5 for MRI (221) and 6 for scintigraphy (543). The pooled estimates are as follows6 :

Reading this table is subtler than it looks, and the authors do it explicitly. Statistically, scintigraphy is the best investigation for establishing a definitive diagnosis : its sensitivity is the highest, and it is the one that misses fewest fractures. But its lower specificity becomes a problem when prevalence is low: across 1,000 patients it would lead to 112 people being overtreated, against 8 with CT. Conversely, CT overtreats almost nobody but would let 56 fractures through where scintigraphy would miss only 26.

The authors add three important caveats: scintigraphy is more invasive, involves radiation and imposes a diagnostic delay of at least 72 hours ; the confidence intervals are wide for all three investigations; and the comparisons are mostly indirect, which exposes them to confounding6.

What the emergency meta-analysis concludes

Carpenter reaches a more clear-cut recommendation, in the specific context of the emergency department: in patients whose initial radiograph shows no fracture but in whom concern persists,MRI is the most accurate investigation, superior to scintigraphy, CT and ultrasound, both for confirming and for ruling out the diagnosis. If MRI is not available, CT is enough to confirm a fracture but remains insufficient to rule one out. The author also notes that MRI and CT share the advantage of identifying other causes of post-traumatic wrist pain3.

The apparent divergence between these two sources can be explained. The Cochrane review reasons on pure statistical accuracy, Carpenter's meta-analysis on clinical usefulness in the emergency setting, taking in availability, delay and invasiveness. For a physiotherapist, the practical conclusion is a single one: when doubt persists, cross-sectional imaging settles it, and passive waiting is not a diagnostic strategy.

Cast or surgery? What the SWIFFT trial settled

A large pragmatic trial, five years of follow-up, and a conclusion that reversed a surgical trend.

The trial and its primary result

SWIFFT is a pragmatic, multicentre, open-label randomised superiority trial conducted in 31 hospitals in England and Wales. It included adults aged 16 and over with a bicortical fracture of the scaphoid waist displaced by 2 mm or less. Of 1,047 patients assessed, 439 were randomised (mean age 33, 363 men or 83 %) between early surgical fixation (n = 219) and below-elbow cast immobilisation, followed by immediate fixation if nonunion was confirmed (n = 220)7.

The primary outcome was the PRWE score at 52 weeks. The results:

• No significant difference : adjusted mean of 11.9 (95 % CI 9.2 to 14.5) in the surgery group against 14.0 (95 % CI 11.3 to 16.6) in the cast group, an adjusted difference of 2.1 points (95 % CI 5.8 to 1.6), p = 0.27.
• Potentially serious complications : 31 patients out of 219 (14 %) in the surgery group, against 3 out of 220 (1 %) in the cast group.
• Cast-related complications : 5 patients (2 %) in the surgery group against 40 (18 %) in the cast group.
• Medical complications were equivalent (2 % in each group).

The authors' recommendation is explicit: adults with a waist fracture displaced by 2 mm or less should receive initial cast immobilisation, with any suspected nonunion confirmed and then fixed immediately. That strategy avoids the risks of surgery and reserves it for the fractures that do not unite7.

The five-year follow-up confirms it, and adds a nuance

The five-year follow-up, published in 2026, reinforces this result. Across 344 patients who provided a valid PRWE score (78.4 % of the initial cohort), no significant difference appeared between the groups: a mean difference of 0.6 points (95 % CI 2.4 to 3.6), p = 0.709. Neither the pain and function subscores, nor the global estimate of treatment effect differed. Grip strength and range of motion were comparable. The nonunion rate among imaged patients remained very low: 3 out of 146 (2.1 %) in the fixation group against 4 out of 121 (3.3 %) in the immobilisation group8.

The radiological arm of the same follow-up brings two pieces of information a physiotherapist needs to know9 :

• Fractures with at least 20 % bony bridging at one year united over time, without intervention. Incomplete union at one year is therefore not synonymous with failure.
• Osteoarthritis progresses in both groups. At five years, 140 patients out of the 267 imaged (52.4 %) had osteoarthritis in at least one joint, with a prevalence, a number of joints involved and a maximum severity similar in both arms. And the mean PRWE score was higher in patients whose osteoarthritis was more severe, reflecting more pain and poorer function.

That last point deserves emphasis: early surgery does not protect against the development of osteoarthritis, and that development is not silent.

How long to immobilise, and in what cast?

This is the question where the temptation to immobilise less is most costly, and where the evidence is old but clear.

Gellman's trial: short against long

The benchmark randomised trial on this question dates from 1989 and is still cited for the simple reason that no more recent trial has produced as clear a result on this precise point. Fifty-one patients with an undisplaced scaphoid fracture were allocated to two forms of immobilisation, with follow-up at least until union and a mean duration of twelve months:

• Long thumb-spica cast (n = 28), replaced by a short cast after six weeks;
• Short thumb-spica cast from the outset and maintained (n = 23).

The results are as follows10 :

Three lessons follow. First, more restrictive initial immobilisation shortens the time to union by more than three weeks. Second, it clearly reduces the number of nonunions and delayed unions. Third, and this is the most useful point in practice, the advantage depends on the site of the fracture line : it was significant for fractures of the proximal third and the waist, whereas distal third fractures did well whatever the form of immobilisation10.

The trial has to be placed for what it is: 51 patients, a 1989 publication, immobilisation practices that have moved on since. It does not set a protocol, but it clearly documents the direction of the effect, and that direction is consistent with the vascular physiology described above.

What becomes of a fracture diagnosed late?

The good news is real, and it does not remove the need to make the diagnosis early.

A missed fracture can still unite in a cast

Grewal's study assessed the outcome of so-called subacute fractures, that is, diagnosed between six weeks and six months after the injury, and treated with a cast alone. Twenty-eight patients were included (20 men, 8 women, mean age 30), with 20 waist fractures, 7 proximal pole and 1 distal pole, with union assessed by CT.

The results are encouraging11 :

• An overall union rate of 82 % (23 out of 28) with a cast alone, despite the diagnostic delay.
• A mean immobilisation of 11 weeks for the waist and 14 weeks for the proximal pole.
• Three factors increased the risk of nonunion in that cohort: diabetes, the presence of comminution and the hump-shaped deformity (humpback deformity).
• Excluding those cases, the union rate reached 96 % (23 out of 24).

The authors conclude that subacute scaphoid fractures, up to six months from injury, can unite with a cast alone, even if the initial diagnosis was delayed, and that the expected time to union is shorter than previously reported. It is a level IV study, retrospective and without a control group: it describes an outcome, it does not compare strategies.

What becomes of an untreated nonunion

When union does not occur, the classically described course is degenerative osteoarthritis of the wrist following a stereotyped sequence, scaphoid nonunion advanced collapse or SNAC wrist12. That established osteoarthritis, its stages and its salvage procedures are the subject of a separate article on this site: carpal osteoarthritis of the wrist. This article stops where that one begins, at the fracture and its union.

But Buijze's review introduces here an intellectual caveat that deserves to be reported as it stands, because it is rarely mentioned: the correlation between symptoms and disease is poor, and the true natural history is debatable, since only symptomatic patients who present are assessed. The authors go further: it is not established that surgery alters the natural history, even when union is achieved12.

That finding is not an invitation to neglect the diagnosis, it is an invitation to measured language. Clinical reasoning remains unchanged: early diagnosis avoids heavier treatment, there is no benefit in delay, and caution is called for in any wrist pain that drags on. But telling a patient that osteoarthritis is inevitable goes beyond what the data allow.

What does a real case report teach us?

A published case, with its identifier, that reproduces exactly the trap described in this article.

How do you apply all this on Monday morning?

What these data change in the assessment, the referral and the conduct of rehabilitation.

The diagnostic reflex, including in a physiotherapy clinic

The physiotherapist is not the one who requests imaging, but they are very often the one who sees these patients repeatedly, and therefore the one who can catch a missed diagnosis. Three situations should prompt a return to the doctor:

• A “wrist sprain” after a fall on the hand that is not getting better within the expected time, with persistent pain on the radial side.
• Pain reproduced by palpating the anatomical snuffbox, the sensitivity of which is the highest of the available tests4.
• Pain reproduced by resisted supination, a sign whose reported performance is the highest in Coventry's review, subject to the external validation its authors call for5.

Conversely, the absence of anatomical snuffbox tenderness is the only element that substantially lowers the probability of fracture, with a negative likelihood ratio of 0.153 - 0.25 depending on the source. That does not rule it out, but it is the most useful clinical information available.

During immobilisation

• Do not negotiate the duration downwards. It is imaging that allows the cast to come off, not the disappearance of pain10.
• Maintain what is not immobilised : the long fingers, the elbow and the shoulder, whose stiffening later costs rehabilitation time with no benefit at all for union.
• Watch for cast complications, which are not rare: they affected 18 % of patients in the cast arm of SWIFFT7.

After immobilisation

• Regain range gradually, bearing in mind that a fracture which required 11 to 14 weeks in a cast leaves a stiffness proportionate to that duration11.
• Restore strength last, after union has been confirmed.
• Be wary of pain that persists or returns when loading resumes: a nonunion can present that way, and the follow-up recommended for conservative treatment includes clinical and CT assessment at three months14.
• Do not promise inevitable osteoarthritis in the event of nonunion: the data on natural history are more uncertain than the usual account suggests12.

Frequently asked questions

Is a normal radiograph enough to rule out a scaphoid fracture?

No, and that is the central message of this article. In emergency department patients with clinical suspicion and a non-diagnostic initial radiograph, the pre-test probability of fracture is estimated at 25 %, with a spread from 12 to 57 % across studies3. Other work measuring the same quantity finds 9.0 %5 or a median of 20 %6. Whatever figure is used, the conclusion is identical: a normal radiograph does not rule the diagnosis out, and the strategy of a repeat radiograph at six weeks has been judged unsuitable15.

Which investigation should be requested when the radiograph is normal?

In the emergency setting, Carpenter's meta-analysis concludes that MRI is the most accurate investigation, superior to scintigraphy, CT and ultrasound, both for confirming and for ruling out the diagnosis; failing that, CT can confirm but remains insufficient to rule out3. The Cochrane review, reasoning on pure statistical accuracy, names scintigraphy as the best performing, while stressing that it is more invasive, involves radiation, imposes a delay of at least 72 hours and would lead to 112 patients out of 1,000 being overtreated against 8 with CT6. The decision rests with the prescriber.

Should a scaphoid fracture be operated on?

For a bicortical waist fracture displaced by 2 mm or less, no. The SWIFFT trial found no difference in functional score at one year between early surgery and casting, whereas potentially serious complications affected 14 % of those operated on against 1 % of those in a cast7. The equivalence still held at five years, with nonunion rates of 2.1 % and 3.3 %8. The recommended strategy is cast first, with immediate fixation if nonunion is confirmed. Fractures displaced by more than 2 mm and those of the proximal pole do not fall within that frame.

Why does this fracture take so long to unite?

Because the fracture line often cuts off the blood supply to the proximal fragment. The main artery enters through the distal pole and runs up towards the proximal pole: the more proximal the line, the more dependent the fragment deprived of supply. That is why the time to union depends on the site, as Grewal's study shows, with 11 weeks of immobilisation on average for the waist against 14 weeks for the proximal pole11.

My cast is a nuisance, can it come off earlier?

That is precisely the decision that exposes you to nonunion. In Gellman's randomised trial, more restrictive initial immobilisation achieved union in 9.5 weeks against 12.7 weeks, with no nonunion against two in the short immobilisation group, the advantage being significant for fractures of the proximal third and the waist10. The disappearance of pain does not mean union in a bone whose proximal fragment may be devascularised: it is imaging that allows the cast to come off.

My fracture was diagnosed several weeks late, is it lost?

No, and that is reassuring information to give. In Grewal's series covering fractures diagnosed between six weeks and six months from injury and treated with a cast alone, the union rate reached 82 %, and 96 % after excluding patients with diabetes, comminuted fractures and humpback deformities11. It is a retrospective series of 28 patients, level IV evidence: it describes a favourable outcome, it does not guarantee an individual result.

Does a nonunion inevitably lead to osteoarthritis?

The classically described course is the SNAC wrist, a progressive degenerative osteoarthritis. But Buijze's review adds a rarely cited caveat: the correlation between symptoms and disease is poor, the true natural history is debatable since only symptomatic patients who present are assessed, and it is not established that surgery alters that natural history, even when union is achieved12. Note also that in the SWIFFT trial, 52.4 % of patients imaged at five years had osteoarthritis in at least one joint, with a similar prevalence after surgery and after casting9.

When can sport be resumed?

None of the sources used for this article provides a validated return-to-sport criterion specific to this fracture, and it is better to say so than to offer a convenient timescale. The reasoning rests on union confirmed by imaging, and not on the disappearance of pain alone. Two useful markers: the immobilisation times observed range from 9.5 to 14 weeks depending on the form and the site1011, and the recommended conservative follow-up includes clinical and CT assessment at three months14.

Bibliography

Fifteen references, each verified individually on PubMed through the E-utilities interface: identifier resolved, title, journal, year, pagination and author list checked on the record itself, abstract read before citation. The links point to the PubMed record.

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