Scaphoid Injury

Updated: Dec 05, 2017
  • Author: Scott R Laker, MD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Overview

Background

Scaphoid fractures are the most common type of wrist fracture, accounting for 10% of all hand fractures and up to 60-70% of all carpal fractures. [1]  They frequently occur after a fall on an outstretched hand. Plain radiographs after the initial injury may not reveal a fracture, and a delay in the diagnosis and treatment of a scaphoid fracture can alter the prognosis for union, increasing the risk of avascular necrosis and the long-term likelihood of arthritis.

Related Medscape Drugs & Diseases topics:

Avascular Necrosis

Wrist Fracture in Emergency Medicine

Wrist Fractures and Dislocations

Scapholunate Advanced Collapse

Scaphoid Fracture Imaging

Related Medscape resource:

Resource Center Fracture

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Pathophysiology

Anatomic considerations

The carpus contains eight small bones, which are arranged in two rows, proximal and distal. The proximal bones, from the radial to the medial side, are the scaphoid, lunate, triquetrum, and pisiform. Only the scaphoid and lunate articulate with the radius; thus, these 2 bones transmit the entire force of a fall on the hand to the forearm. The distal bones are, starting from the radial side, the trapezium, trapezoid, capitate, and hamate. In scaphoid injury, pain is often elicited in palpation of the anatomic snuffbox, which is bordered by the extensor pollicis longus tendon medially, the extensor pollicis brevis and abductor pollicis longus tendons laterally, and the styloid process of the radius proximally. 

Blood supply

Anatomically, the scaphoid may be divided into proximal, middle (termed the waist), and distal thirds. The scaphoid is unique in that it is supplied by the palmar carpal branch of the radial artery from the distal to the proximal pole. Fractures of the proximal third of the scaphoid account for 15% of scaphoid fractures, those of the middle portion account for 65%, those of the distal tuberosity account for 10%, and fractures of the distal body make up the remaining 10%. [2]  Diminished blood flow to the proximal pole is noted in about one third of fractures at the waist level. Since supply to the proximal pole is tenuous, disruption may result in avascular necrosis. Almost 100% of proximal pole fractures result in aseptic necrosis. Displaced scaphoid fractures have a nonunion rate of 55-90%.

Fall onto outstretched hand

The usual mechanism of injury is a fall onto the outstretched hand (FOOSH) that results in forceful hyperextension of the wrist and impaction of the scaphoid against the dorsal rim of the radius. This mechanism explains why snuffbox tenderness is so common, even in the absence of a scaphoid fracture. Conventional medical wisdom dictates that snuffbox tenderness should be equated with a scaphoid fracture unless radiographs prove otherwise. If initial radiographs do not show fracture, follow-up radiographs should be obtained in 7-14 days, because the fracture line may be more visible after some resorption.

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Epidemiology

Frequency

United States

Scaphoid fracture has been reported in people aged 10-70 years, although it is most common in young adult men following a fall, athletic injury, or motor vehicle accident.

Mortality/Morbidity

The scaphoid has no ligamentous or tendinous attachments, but joint compressive forces, trapezial-scaphoid shear stress, and capitolunate rotation moments exert control on the scaphoid. Therefore, scaphoid fractures have a high incidence of nonunion (8-10%), frequent malunion, and late sequelae of carpal instability and posttraumatic arthritis.

  • A higher incidence of aseptic necrosis and nonunion is noted with fractures of the proximal pole of the scaphoid, due to the blood supply (as detailed above).

  • A scaphoid fracture can present as a nondisplaced, stable fracture or as a displaced, unstable fracture. Displaced fractures frequently are associated with ligamentous tears in the wrist and require thorough evaluation and follow-up.

Race

No known correlation exists between race and scaphoid fracture.

Sex

Scaphoid injuries are more common in men than in women.

Age

Scaphoid fracture is uncommon in children because the physis of the distal radius usually fails first, resulting in Salter type I or II fractures of the distal radius. Similarly, in elderly patients, the distal radial metaphysis usually fails before the scaphoid can fracture.

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Patient Education

The patient should be informed that degenerative arthritis of the wrist is highly likely, but this condition may take years to develop, depending on the amount of chronic stress applied to the wrist.

To help prevent further morbidity, patients can be educated on the basics of wrist injury and how to properly care for their cast or splint. Common symptoms of wrist injury, including pain, swelling, bruising, stiffness, and weakness, can be discussed. In addition, patients can be counseled to monitor for warning signs and symptoms such as numbness and tingling (possible nerve injury), intractable pain (possible avascular necrosis), and redness, swelling, warmth, and tenderness (possible infection).

If the patient is using acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs), it is important to recommend adherence to prescribed limits, given the adverse effects associated with increased dosages. Treatment can also be covered, including rest, ice, elevation or elastic bandaging, or, in some cases, surgery. Discussion of proper cast and splint care is warranted, as is determination of a general timeline for the wrist sprain or fracture to heal. Special care should be taken for patients in labor-heavy industries or those whose activities place significant stress on the wrist. If warranted, smoking cessation is encouraged, as active smoking may prolong fracture healing. Appropriate follow-up and aggressive rehabilitation should also be emphasized to the patient.

For patient education information, see the articles Broken Hand and Wrist Injury.

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