Journal of the Accident and Medical Practitioners Association (JAMPA) 2004; Vol. 1 (No. 2)
 Accident and Medical Practitioners Association, New Zealand
___________________________________________________________________________
Scaphoid Injury:
Optimal Diagnosis and Treatment
Alistair Blomley, MB BS, FRNZCGP, FAMPA
The Riccarton Clinic and After Hours, Riccarton, Christchurch
About the author:
Dr Alistair Blomley, MB BS, FRNZCGP, FAMPA, is a General Practitioner and A&M doctor
working in a Level 2 A&M clinic in Christchurch. His clinical interests are orthopaedics,
sports injuries, and all aspects of acute care.
Address for correspondence: Dr Alistair Blomley, MB BS, FRNZCGP, FAMPA, The
Riccarton Clinic and After Hours, 6 Yaldhurst Rd, Riccarton, Christchurch
E-mail: ab@riccartonclinic.co.nz
Issues this article will address

Diagnosing the “clinically fractured scaphoid”

Radiological investigation of the suspected scaphoid injury

Treatment and follow-up of scaphoid fractures
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Salient Points

Scaphoid fracture can be a difficult injury to diagnose

Immobilising the wrist on clinical impression, even if initial x-rays are normal, is
accepted practice.

If a scaphoid injury is suspected, and scaphoid views requested, plaster cast
immobilisation and follow-up at 10 to 14 days is mandatory.

Anatomical snuff box tenderness as a sign of clinical fracture has a low specificity.

MRI scanning is the investigation of choice.

Cast immobilisation remains the recommended first-line treatment for stable
fractures.

Because of the significant problems presented by non-union, it is wise to clinically
and radiologically reassess all scaphoid fractures at 6 months after injury.
Key words: Scaphoid injury · Clinically fractured scaphoid · Diagnosis · Treatment ·
Percutaneous screw fixation · Avascular necrosis
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Introduction
The scaphoid is one of the 8 carpal bones. It lies in the proximal row, has a vertical
orientation and, along with the lunate, has an articulation with the distal radius. The two rows
of carpal bones are bridged by the scaphoid, and it is the major bony block to extreme
dorsiflexion of the wrist. The distal volar wrist crease crosses the waist of the scaphoid.
In a sporting society like New Zealand, wrist injuries are commonplace. However, scaphoid
fracture can be a difficult injury to diagnose, and immobilising the wrist on clinical
impression, even if initial x-rays are normal, is standard, accepted and ‘traditional’ practice.
A clear understanding of the potential mechanisms of injury, clinical signs of fracture, and
available radiological investigative techniques is important in helping patients receive timely
and comprehensive treatment and follow-up, and avoiding long periods of unproductive
immobilisation.
Peak Incidence
Scaphoid fracture is the most common injury to the carpal bones, comprising >60% of all
carpal injuries. The peak incidence is in young adults aged 15 to 30 years.[1]
As ossification begins at about 5 to 6 years of age and is not complete until 13 to 15 years of
age,[2] the scaphoid is mostly cartilaginous in young children. This renders it less susceptible
to fracture, since the cartilage confers flexibility and a cushioning effect. However, studies
have reported scaphoid fracture in children as young as 9 years of age.[3]
Mechanism of Injury
A significant direct force to the outstretched dorsiflexed hand can result in fracture. However,
a direct blow to the scaphoid area or a twisting injury to the wrist is highly unlikely to fracture
the scaphoid, and therefore the injury does not need to be treated as a clinical scaphoid
fracture if x-rays are normal.[4]
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Around 80% of scaphoid fractures occur through the middle third, i.e. the body or waist,
while 10% involve the distal third, and 10% the proximal third.[5]
Note: the term “clinically fractured scaphoid” is used to describe a wrist injury suspicious for
scaphoid fracture where there are corresponding clinical signs and normal initial scaphoid
series x-rays.
Traditional Management of Clinical Scaphoid Injury
If a scaphoid injury is suspected and scaphoid views have been requested, then plaster cast
immobilisation and follow-up at 7 to 10 days should be mandatory. “If you think it, do it”. At
this time, resorption of bone around the fracture will have occurred and most fractures
become obvious. Immobilisation should be continued for a minimum of 6 weeks, and the
need for further immobilisation then assessed clinically and radiologically.
Clinical Signs of Possible Scaphoid Fracture
Because pain is often minimal in the initial phase, scaphoid fractures are easy to overlook but
must be suspected if the mechanism of injury is appropriate (see above). There are many
ways of identifying a clinically suspected fracture. Tenderness in the anatomical snuff box
(ASB) region is probably the most widely known and used sign by primary care clinicians.
Although this test is very sensitive, it has low specificity – resulting in a high rate of casting
of normal wrists, with subsequent time off work, cost implications, and potential
complications of plastering.
A number of studies have tried to identify how reliable clinical examination is at diagnosing
fractures. In a study that evaluated the efficacy of four signs of possible fracture – ASB
tenderness; scaphoid tubercle (ST) tenderness; pain on longitudinal compression of the thumb
(LC); and range of thumb movement (MT) – it was found that ASB, LC, ST were all 100%
sensitive but their specificities were only 9%, 30%, and 48%, respectively.[6] This means
that if ASB tenderness is relied upon as the only clinical marker for scaphoid fracture, we
could expect a true fracture rate of only 1 in 10 people that we sentence to 2 weeks of plaster
casting. However, when the above 3 signs are combined, the specificity improves to 74%.[6]
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Pain with thumb movement was found to be both insensitive (69%) and nonspecific (66%) in
the same study.[6] In another series, scaphoid compression tenderness was found to be 100%
sensitive and 80% specific for scaphoid fracture.[7]
It is clear, therefore, that accurate clinical diagnosis of scaphoid injury remains very difficult,
and that accurate radiology is needed to provide appropriate treatment.
X-ray Investigation
Multiple views of the scaphoid should be taken when injury is suspected. A fracture can be
difficult to spot, and comparative films of the uninjured side can be used to compare what
may be normal bone markings or abnormalities of ossification.[8] Scaphoid films have been
reported to have a false-positive diagnostic rate of up to 20%.[9]
A normal stripe of soft tissue can be identified paralleling the lateral aspect of the scaphoid.
This thin stripe is obliterated or displaced (convex laterally) in the case of scaphoid fracture.
If the fat stripe is clearly visible and is straight or concave in the acute case, then a scaphoid
fracture is highly unlikely.[10]
Other Imaging Techniques
A bone scan is an excellent and cost-effective (approximately NZ$250) investigation to rule
out a scaphoid fracture, and possibly save the patient 2 weeks of time off work and
unnecessary cast immobilisation. In 1979, it was reported that a negative bone scan 24 to 72
hours after injury excluded the possibility of a scaphoid fracture.[11] Although day 4 bone
scans have been shown to be 100% sensitive, they are only 92% specific. False-positives can
occur in the presence of acute tenosynovitis,[12] in elderly patients with arthritis, and in
children with open epiphyses.[13] Therefore, day 4 bone scans do not reliably confirm the
diagnosis of scaphoid fracture.[12]
Although expensive, MRI scanning is the investigation of choice and this technique is also
useful for identifying associated soft tissue injuries that bone scans don’t pick up. A study
evaluating MRI use in the management of clinical scaphoid fracture found that 19% of
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patients did indeed have a fracture, while 14% had a radius fracture, and 5% had other carpal
bone injuries.[14] As a result, 60% of patients in this study escaped the mandatory 2-week
period of cast immobilisation. In a Canadian study that evaluated MRI use in 186 consecutive
patients with clinical scaphoid fracture diagnosed in the emergency department, 94.6% had
repeat imaging and only 3.9% had a true scaphoid fracture (95% CI 2.1-5.7%).[15]
A study in an American radiology department that identified a true fracture rate of 25% found
that the cost of MR imaging was comparable to the costs incurred with ‘traditional’
immobilisation and radiographic follow-up.[16] The authors estimated the respective costs to
be US$677 for the ‘traditional’ approach compared with US$770 for MRI. However, this cost
analysis did not take into account the loss of productivity by patients who were unnecessarily
immobilised in plaster. In New Zealand, the current cost of a limited MRI of the scaphoid is
approximately NZ$300.
All scaphoid fractures identified by MRI can also be identified by bone scan,[17] but
ligamentous injury and carpal instability diagnosed by MRI are not evident on a bone scan.
Optimal Treatment of Scaphoid Injury (Casting)
The traditional scaphoid cast is applied with the wrist fully pronated, radially deviated, and
moderately dorsiflexed, with the thumb in mid-abduction and the plaster running up to the
thumb interphalangeal joint (IPJ). A randomised, prospective trial undertaken in the UK to
assess whether the thumb needs to be immobilised used conventional scaphoid casts with the
thumb incorporated up to the IPJ and Colles-type casts with the thumb left free. After 6
months, the incidence of non-union was independent of the type of cast used.[18] Wrist
position has been found not to influence the rate of union of scaphoid fracture (89%), but
patients immobilised in flexion show a greater restriction of wrist dorsiflexion than those
splinted in slight extension.[19]
Cast immobilisation remains the recommended first-line treatment for stable fractures.
However, there is growing interest in closed reduction and the use of percutaneous screw or
pin fixation (PCFS). The latter technique has been shown to produce consistently good
results.[20] It is minimally invasive and can be done under Bier’s block. Casting
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postoperatively is not required and wrist movements can be regained early. A >95% primary
radiologic union rate has been reported.[20]
Open reduction is recommended for all other displaced fractures – which obviously need
orthopaedic referral.
Complications of Scaphoid Fractures
The principal complications that may arise are:
1. Avascular necrosis (AVN): as the blood supply to the scaphoid enters distally, about
30% of waist and nearly 100% of proximal pole fractures result in AVN if adequate
stabilisation of the fracture is not achieved.[21]
2. Non-union: the most important factor leading to non-union of scaphoid fractures is
delayed or inadequate stabilisation. This is the reason why clinically suspected fractures
are treated as such, even if initial x-rays are normal. A retrospective study of 30 patients
with non-union of scaphoid fractures seen at a UK hospital found that the patients
presented at a mean of 5 years after the initial injury, and 3 of these cases ended up
involving litigation.[22] Non-union is associated with later arthritic change. Prompt
diagnosis and treatment of non-union is therefore vital, whether symptomatic or not, to
prevent osteoarthritis developing in the future.
Importance of Follow-up
Because of the significant problems presented by non-union, it is wise to clinically and
radiologically reassess all scaphoid fractures at 6 months after injury.
Conclusion
In an ideal world, an immediate MRI scan of patients with scaphoid injuries would be the
optimal diagnostic approach. If this reveals a fracture, the option of a percutaneous screw
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fixation and immediate return to work/activity is infinitely preferable over a 6- to 12-week
period of troublesome casting.
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