Scaphoid Fractures

Natasha,  a 13-year old girl, attends the Emergency Department with pain in the right wrist after falling onto her outstretched hand whilst ice skating. There is minimal swelling, but she is reluctant to move the wrist. She is tender on palpation of the anatomical snuffbox and on telescoping of the thumb. A senior colleague suggests this could be a scaphoid fracture and advises some plain radiographs. These show no bony injury, so she is placed in a wrist splint and referred for outpatient follow-up with the orthopaedic surgeons.

What is the scaphoid?

The scaphoid lies between the proximal and distal rows of carpal bones, on the radial side of the wrist. Its name comes from the Greek ‘skaphos’, meaning boat, due to its boat-like shape. It starts to ossify between the ages of four and six years, forming two poles (proximal and distal) united by the waist. Ossification occurs from the distal pole and moves proximally. During ossification, it is protected by cartilage. The scaphoid receives its blood supply from the branches of the radial artery, but due to retrograde flow, the blood supply can be interrupted when the bone is fractured, risking avascular necrosis.  Full ossification is usually complete by age 13 in girls and 15 in boys.

How common is scaphoid fracture in children?

Scaphoid fractures are uncommon in young children, due to protection of the bone during its ossification by a thick layer of cartilage and soft tissue. Cartilaginous fractures are possible but require reasonable force; simple soft tissue injuries are more common in younger age groups. Bony scaphoid fractures are seen predominantly in older children (ages 12-15). Any fracture diagnosed in the presence of growth plates seen elsewhere on radiographs are classified as paediatric fractures.

Mechanism of Injury:

 The injury pattern for scaphoid fractures is similar to that of adults, with the typical presentation being a fall onto an outstretched hand. Scaphoid fractures may also result from punching against resistance. This injury should also be considered in higher impact trauma, where the wrists are forcefully hyperextended against resistance; a child putting their arms out against a dashboard or front seat in the context of a car accident may lead to scaphoid fracture.

Examination Findings:

As with any orthopaedic examination, it is time to use the principle of look, feel and, finally, move.

As well as examining the distal radius and ulna, any wrist examination should include consideration of the scaphoid as the area of injury.

Although there is no positive finding which is pathognomonic of a scaphoid fracture, there are clues which should increase our clinical suspicion (see below)

Tenderness in the anatomical snuffbox – located in the first web space.

Tenderness of the scaphoid tubercle – located on the proximal palm at the base of the thumb

Pain elicited on axial loading, or ‘telescoping’ of the thumb.

Bear in mind that other injuries may be present.

Children can be difficult to assess, and if they are behaving as though they have a fracture, it can be difficult to rule out anything based on examination alone. Have a low threshold for imaging an area in which you are suspicious of a bony injury.

Imaging:

NICE recommends MRI as the first line imaging modality in suspected scaphoid fractures. MRI is not only expensive, but most emergency departments have restricted access to this investigation. Plain radiographs miss up to 25% scaphoid fractures across all age groups (Pincus, 2009), but this is our most readily available test.

A scaphoid series of plain x-rays includes four views: postero-anterior (PA), pronated, lateral, and supinated. A further view, PA with a clenched fist, allows some assessment of the scapholunate ligament integrity – although soft tissues cannot reliably be assessed on plain radiographs, a widened space between the scaphoid and lunate may suggest ligamentous disruption.

Plain x-rays are very specific – the presence of a cortical interruption or trabecular abnormality is highly likely to represent a true fracture. However, a normal radiograph is not sensitive enough to rule out a fracture. Patients with normal radiographs, in the presence of clinical symptoms or signs suggestive of a fracture, should be treated as such, and require further imaging, either in the form of repeat films 10-14 days post-injury, or an early MRI.

Fracture Patterns in Children:

Due to the scaphoid ossifying from the distal pole proximally, this is the most likely part of the bone to fracture first in children (Gajdobranski, 2014). Unlike in adults, the middle and proximal parts of the bone are less frequently encountered. Similar to other fractures in paediatric patients, scaphoid fractures in this younger age group may be incomplete (uni-cortical) or non-displaced.

Management:

There is some overlap in the management in of suspected and confirmed scaphoid fractures based on the initial x-ray.

Paracetamol, ibuprofen and elevation in a sling are all appropriate whilst waiting for radiology.

If there is a confirmed fracture seen on the patient’s initial imaging, they can have a scaphoid cast applied. This is a below elbow backslab with a thumb spica. These patients should be referred to the fracture clinic for further management.

Normal plain radiographs do not exclude a fracture. In this instance, a wrist splint is appropriate to immobilise the affected area. There is no evidence for splinting with the thumb in extension (Dawson-Bowling, 2014). These patients need to be brought back to the fracture clinic for repeat radiography, or more advanced imaging in the form of MRI, dependent on local protocols.

Most scaphoid fractures in children and teenagers are managed conservatively with a cast. Whilst immobilisation time is usually the final remit of the orthopaedic surgeons, it is helpful to be able to offer children and their parents some advice in the Emergency Department as to how long healing will take. As a rule, the more distal the fracture, the quicker the healing process. This is in part due to the blood supply of the scaphoid. Longer immobilisation times will be needed for middle and proximal fractures.

Occasionally, surgical fixation will be required for significantly displaced fractures, or in cases on non-union. This is beyond the scope of Emergency Department management.

Do not miss scaphoid fractures on wrist x-rays – don’t be distracted by other, more obvious fractures. This patient complained of distal forearm pain but the scaphoid region was not specifically examined. A distal radius fracture and an ulnar styloid fracture were spotted on the x-ray. But, if you look at the very top of the film, you’ll also see a fracture through the scaphoid. Children may not complain of pain exactly over the fracture site, especially when there are fractures elsewhere.

Case Resolution

Natasha is seen at ten days post-injury in the fracture clinic. Her splint is removed and whilst the swelling has improved, her range of motion is still restricted by pain and she remains significantly tender in the anatomical snuffbox. She is booked for an MRI of the wrist, which shows a non-displaced fracture line through the distal pole of the scaphoid. She is placed into a scaphoid plaster cast and remains immobilised for a total of six weeks. When the cast is removed, she has no residual symptoms and makes a full, uncomplicated recovery.