Introduction
Background
The distal radial fracture is the most common forearm fracture. It is usually caused by a fall onto an outstretched hand (FOOSH). It can also result from direct impact or axial forces. The classification of these fractures is based on distal radial angulation and displacement, intra-articular or extra-articular involvement, and associated anomalies of the ulnar or carpal bones.
Most distal radial fractures are diagnosed by conventional radiography. Computed tomography (CT) scanning and magnetic resonance imaging (MRI) are used to evaluate complex distal radial fractures for the assessment of associated injuries and for surgical planning.
For excellent patient education resources, visit eMedicine's Breaks, Fractures, and Dislocations Center. See also eMedicine's patient education article Broken Arm, as well as the clinical eMedicine articles Distal-Third Forearm Fractures; Fractures, Forearm; and Fractures, Wrist. In addition, see the articles Splinting May Be Better Than Casting for Children With Distal Radius or Ulna Buckle Fractures and Closed Reduction Methods for Treating Distal Radial Fractures in Adults, on Medscape.
Pathophysiology
Distal radial fractures occur primarily after a FOOSH mechanism, but subtypes of these fractures occur by other mechanisms.
Frequency
United States
In the United States, 17% of all emergency room visits result from wrist injuries.1,2 In 1992, McMurtry and colleagues reported that distal radial fractures account for one sixth of all fractures seen in the emergency department.
Mortality/Morbidity
Resnick notes that approximately 40-78% of distal radial fractures are associated with the disruption of the triangular fibrocartilage (TFC) complex.3 Scapholunate and lunotriquetral interosseous ligament injuries occur in 20-50% and 10-15% of cases, respectively.
Common complications of distal radial fractures also include ulnar nerve injury, carpal tunnel syndrome, posttraumatic radiocarpal osteoarthritis with possible limited range of motion, heterotopic ossification, reflex sympathetic dystrophy (RSD), tendon rupture, nonunion, and radial shortening.
The most common complication of associated soft-tissue injury is peripheral nerve dysfunction. The median nerve is most commonly affected, but the ulnar nerve also may be injured. Mechanisms for neuropathy of the median nerve include direct trauma by fracture or displacement, injury through a proximal radial fragment, and injury from displacement of a volar fragment. The ulnar nerve is damaged by medial displacement of the radial fragment or by the ulnar head being volarly displaced.4
Injury to arteries occurs with open and closed fractures. It can also occur with markedly displaced fractures and with dislocations of the radius and ulna. Tendon lacerations occur from high-energy injuries and should be suspected with open fractures and high-velocity injuries. The incidence of tendon rupture is less than 0.2%, and tendon rupture is a late sequela of distal radial fractures.4
Intercarpal injuries may accompany fracture dislocations of the distal forearm. Scaphoid fractures are not uncommon. Intercarpal ligament injuries also may occur. Fractures through the radial styloid can disrupt the radioscapholunate and scapholunate interosseous ligaments, causing a disruption between the 2 bones.4 The extensor pollicis longus tendon is most frequently ruptured.
Race
To the authors' knowledge, no racial preferences have been reported.
Sex
Most wrist fractures occur in older postmenopausal women, with a female-to-male ratio of 4:1.5 However, in adolescent boys and girls, the ratio is 3:1, reflecting a differing level of sports involvement between boys and girls.6
Age
A bimodal age distribution has been documented for distal radial fractures; peaks occur at ages 5-14 years and at ages 60-69 years.6
Extra-articular metaphyseal fractures occur in elderly patients because of the thin osteoporotic cortex. Intra-articular fractures with joint surface displacement occur in young patients.
Age influences the location of fractures in the forearm and wrist. Young children present with metaphyseal fractures of the radius and ulna; adolescents, with physeal separations of the radius; and young adults, with scaphoid fractures. Middle-aged and elderly patients present with fractures of only the distal radius or of the radius and ulna.
Anatomy
The radiocarpal joint is a synovial joint that connects the hand to the forearm. The distal radius and ulna articulate at the radioulnar joint. The TFC is a concave, elliptical articular disc that extends from the ulnar side of the radius and forms a bridge to the styloid process of the ulna. The TFC is a key stabilizer of the distal radioulnar joint. A central ridge divides the radial articular surface into the scaphoid and lunate facets.
The pronator quadratus muscle is located across the volar aspect of the distal radius and ulna. This muscle is associated with an underlying fat pad that is seen as a flat, lucent line anterior to the distal end of the radius on the lateral image and that, if a bulge is present, is indicative of a soft-tissue injury.
The TFC is best evaluated by using arthrography or MRI.
Presentation
Wrist injuries that cause pain, edema, crepitus, deformity, or ecchymosis should be evaluated for radial fractures. Missed distal radial fractures can lead to significant morbidity.
A universal classification of distal radial fractures was proposed in 1990. This system differentiates between extra-articular and intra-articular fractures, as well as between stable and unstable fractures; it was created as a treatment-based algorithm. Classification systems are based on the following 2 principles:
- The classification should dictate the treatment.
- The classification should suggest the long-term, functional results of treatment or be correlated with these anticipated results.7
Table 1. Universal Classification of Distal Radial Fractures
Open table in new window
Table
| Classification | Description |
| I | Nonarticular, nondisplaced |
| II A B C | Nonarticular, displaced Reducible, stable Reducible, unstable Irreducible |
| III | Articular, nondisplaced |
| IV A B C D | Articular, displaced Reducible, stable Reducible, unstable Irreducible Complex |
| Classification | Description |
| I | Nonarticular, nondisplaced |
| II A B C | Nonarticular, displaced Reducible, stable Reducible, unstable Irreducible |
| III | Articular, nondisplaced |
| IV A B C D | Articular, displaced Reducible, stable Reducible, unstable Irreducible Complex |
Preferred Examination
Posteroanterior (PA), lateral, and oblique radiographs of the injured forearm should be obtained. Oblique views reveal intra-articular involvement that is not apparent on the other views. The semisupinated, oblique view demonstrates the dorsal facet of the lunate fossa, whereas the partially pronated, oblique PA view allows visualization of the radial styloid.
Radial height is assessed on the PA view. It is a measurement between 2 parallel lines that are perpendicular to the long axis of the radius. One line is drawn on the articular surface of the radius, and the other is drawn at the tip of the radial styloid. The normal radial height is 9.9-17.3 mm.8 Measurements of less than 9 mm in adults suggest the presence of comminuted or impacted fractures of the radial head. Comparison with the contralateral normal wrist is recommended if the diagnosis is unclear (see Images 1-2).
Radial inclination is measured on the PA view; this is a measurement of the radial angle. A line is drawn along the articular surface of the radius perpendicular to the long axis of the radius, and a tangent is drawn from the radial styloid. The normal angle is 15-25º.9,2 Angulation of the radial head also provides impaction clues (see Image 3).
The volar tilt, or palmar inclination, is measured on the lateral view. A line perpendicular to the long axis of the radius is drawn, and a tangent line is drawn along the slope of the dorsal-to-palmar surface of the radius. The normal angle is 10-25º.9,2 A negative volar tilt indicates dorsal angulation of the distal, radial articular surface (see Image 4).1
Ulnar variance is measured on PA radiographs. In adults, the following 3 methods are used8 :
- Project-a-line technique
- Method of perpendiculars
- Concentric-circle technique
Ulnar variance is described as being zero, minus, or plus. Positive (plus) or negative (minus) ulnar variance should be compared with the variance on the contralateral normal forearm.9 Normal ulnar variance is 9-12 mm. Note that ulnar variance does not depend on the length of the ulnar styloid but on the positioning of the forearm, as well as on the radiographic technique (see Image 1).
Because the distal radius and ulna can fracture and because related ligamentous or bony injuries can be occult, an evaluation of the soft tissues of the distal forearm is important. For this assessment, 2 fat planes on the lateral view and 5 fat planes on the PA view are useful.
On the lateral view, the deep fat pad of the pronator quadratus and the dorsal skin subcutaneous fat line can be seen anterior to the distal radius. The deep fat pad of the pronator quadratus forms a slight, ventral concave line. This is convexly bowed in a ventral direction or completely absent in pathologic conditions. The dorsal skin subcutaneous fat line is flat or is a dorsal concave line. It is abnormal when it is convex in the dorsal direction.
The PA view shows the thenar, hypothenar, pararadial, and paraulnar skin subcutaneous fat lines and the deep, navicular fat pad. Swelling that is not associated with an observed fracture should initiate a search for an additional abnormality.
In suspected instances of extensive soft-tissue damage, CT scanning or MRI may be used.
Limitations of Techniques
Plain radiographs do not show the extent of soft-tissue damage or of radioulnar and radiocarpal joint involvement.
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Further Reading
Keywords
broken wrist, broken arm, wrist fractures, forearm fractures, Colles' fracture, Colles fracture, Smith's fracture, Smith fracture, Barton's fracture, Barton fracture, chauffeur's fracture, Hutchinson's fracture, Hutchinson fracture, Galeazzi's fracture, Galeazzi fracture, Piedmont fracture, Essex-Lopresti injury, die-punch fractures, radial styloid, buckle fracture, greenstick fracture
