Fractures of the Distal Radius
Colles Fracture. The most frequently encountered injury to the distal forearm,
Colles fracture, usually results from a fall on the outstretched hand with the forearm pronated in dorsiflexion. It is most commonly seen in adults older than the age of 50 years and more often in women than in men. In the classic description of this injury, known in the European literature as the
Pouteau fracture, the fracture line is extraarticular, usually occurring approximately 2 to 3 cm from the articular surface of the distal radius. In many cases, the distal fragment is radially and dorsally displaced and shows dorsal angulation, although other variants in the alignment of fragments may also be seen (
Fig. 7.9). Commonly, there is an associated fracture of the ulnar styloid process. It should be noted that some authors (e.g., Frykman) include intraarticular extension of the fracture line, as well as an associated fracture of the distal end of the ulna, under this eponym (
Fig. 7.10,
Table 7.3).
Radiographs in the posteroanterior and lateral projections are usually sufficient to demonstrate Colles fracture. The complete evaluation on both views should take note of the status of the radial angle and the palmar inclination as well as the degree of foreshortening of the radius secondary to impaction or bayonet-type displacement (
Figs. 7.11 and
7.12). Computed tomography (CT) scanning may provide additional information concerning the exact position of displaced fragments (
Figs. 7.13,
7.14,
7.15).
Complications. At the time of fracture, a concomitant injury to the median and ulnar nerves may occur. A lack of stability of the fragments during healing may result in a loss of reduction, but delayed union and nonunion are very rarely seen. As a sequela, posttraumatic arthritis may develop in the radiocarpal articulation.
Barton and Hutchinson Fractures. Both these fractures are intraarticular fractures of the distal radius. The classic
Barton fracture affects the dorsal margin of the distal radius and extends into the radiocarpal articulation (
Fig. 7.16); occasionally, there may also be an associated dislocation in the joint. When the fracture involves the volar margin of the distal radius with an intraarticular extension, it is known as a
reverse (or
volar)
Barton fracture (
Fig. 7.17). Because in both variants the fracture line is oriented in the coronal plane, it is best demonstrated on the lateral or oblique projections.
The
Hutchinson fracture (also known as chauffeur’s fracture—a name derived from the era of hand-cranked automobiles when direct trauma to the radial side of the wrist was often sustained from recoil of the crank) involves the radial (lateral) margin of the distal radius, extending through the radial styloid process into the radiocarpal articulation. Because of the sagittal orientation of the fracture line, the posteroanterior view is better suited to diagnose this type of injury (
Fig. 7.18).
Smith Fracture. Usually resulting from a fall on the back of the hand or a direct blow to the dorsum of the hand in palmar flexion, a Smith fracture consists of a fracture of the distal radius, which sometimes extends into the radiocarpal joint, with volar displacement and angulation of the distal fragment (
Fig. 7.19). Because the deformity in this fracture is the opposite of that seen in a Colles injury, it is often referred to as a reverse Colles fracture; it is, however, much less common than Colles. There are three types of Smith fracture, defined on the basis of the obliquity of the fracture line (
Fig. 7.20), which is best assessed on the lateral projection. Types II and III are usually unstable and may require surgical intervention.
Galeazzi Fracture-Dislocation. This abnormality, which may result indirectly from a fall on the outstretched hand combined with marked pronation of the forearm or directly from a blow to the dorsolateral aspect of the wrist, consists of a fracture of the distal third of the radius, sometimes extending into the radiocarpal articulation and an associated dislocation in the distal radioulnar joint. Characteristically, the proximal end of the distal fragment is dorsally displaced, commonly with dorsal angulation at the fracture site; the ulna is dorsally and ulnarly (medially) dislocated (
Fig. 7.21). On rare occasion, the distal fragment of the radius is volarly (anteriorly) displaced in relation to the proximal fragment and medially angulated (
Fig. 7.22). Two types of Galeazzi injury have been identified. In type I, the fracture of the radius is extraarticular in the distal third of the bone (see
Figs. 7.21 and
7.22). In type II, the radius fracture is usually comminuted and extends into the radiocarpal joint (
Fig. 7.23).
Posteroanterior and lateral radiographs are routinely obtained when this injury is suspected, but the lateral view clearly reveals its nature and extent (see
Figs. 7.21B,
7.22C, and
7.23B).
Piedmont Fracture. An isolated fracture of the radius at the junction of the middle and distal thirds without an associated disruption of the distal radioulnar joint is known as the Piedmont fracture (
Fig. 7.24A). This injury is also called “fracture of necessity,” because open reduction and internal fixation are necessary to achieve an acceptable functional result (
Fig. 7.24B). If this fracture is treated conservatively with closed reduction and cast application, then the interosseous space may be compromised because of muscle action, resulting in the loss of pronation and supination after the bone union is completed.
Essex-Lopresti Fracture-Dislocation. This fracture, which affects the radial head and is associated with a tear of the interosseous membrane of the forearm and dislocation in the distal radioulnar joint, was discussed in
Chapter 6.
Ulnar Impingement Syndrome. Ulnar impingement syndrome is caused by a short distal ulna that impinges on the distal radius proximal to the sigmoid notch. A short ulna may represent a congenital anomaly, such as negative ulnar variance, or may be the result of premature fusion of the distal ulnar growth plate secondary to previous trauma. In most cases, however, it is caused by surgical procedures that involve a resection of the distal ulna secondary to trauma, rheumatoid arthritis, or correction of a Madelung deformity. The clinical symptoms of the ulnar impingement syndrome consist of ulnar-sided wrist pain and limitation of motion in the radiocarpal joint. In addition, patients experience discomfort during pronation and supination of the forearm. On radiography, the characteristic changes of this abnormality include a short ulna and scalloping of the medial aspect of the distal radius, in cases of negative ulnar variance (
Fig. 7.25) or premature
fusion of the distal ulnar growth plate, or radial scalloping and radioulnar convergence, in cases of distal ulnar resection. Before these findings become obvious on conventional radiologic studies, magnetic resonance imaging (MRI) may be helpful in early recognition of this condition.
Ulnar Impaction Syndrome. Also known as the ulnolunate abutment syndrome or ulnocarpal loading, the ulnar impaction syndrome is a well-recognized entity clinically characterized by ulnar-sided wrist pain and limitation of motion in the radiocarpal joint. It is frequently associated with the positive ulnar variance. The pathologic mechanism of this syndrome is linked to altered and increased forces transmitted across the ulnar side of the wrist, leading to a compression of the distal
ulna on the medial surface of the lunate bone. This causes the development of degenerative changes in the cartilage covering both bones. In addition, frequent association of the tear of the triangular fibrocartilage has been reported. In cases of excessive ulnar length, dorsal subluxation of the ulna is present compromising supination of the forearm. The conventional radiography shows a positive ulnar variance associated with significantly decreased ulnolunate interval and occasionally foci of sclerosis or cystic changes in the lunate (
Fig. 7.26). MRI is the most effective technique for the diagnosis of this syndrome and demonstration of pathologic changes in the affected bones and surrounding soft tissues. MRI reveals bone marrow edema of the distal ulna and lunate, subchondral sclerosis and cyst formation, and destruction of the cartilage. Associated abnormalities, such as tears of the triangular fibrocartilage and lunotriquetral ligament, are also well imaged (
Figs. 7.27 and
7.28). Treatment of this condition includes TFCC debridement and ulnar shortening.
Injury to the Soft Tissue at the Distal Radioulnar Articulation
One of the most common sequelae of injury to the distal radioulnar articulation is a tear of the TFCC. A tear may occur as the result of fractures such as those described in the preceding sections or independently after an injury to the distal forearm and wrist.
Radiographs in the standard projections are invariably normal regarding the status of the triangular cartilage, particularly if there is no evidence of fracture or dislocation on which to base a suspicion of soft-tissue injury. When it is suspected, however, a single-contrast arthrogram of the wrist can confirm or exclude the diagnosis. Normally, a contrast fills the radiocarpal compartment, the prestyloid and volar radial recesses, and the pisotriquetral space (see
Fig. 7.7). The presence of a contrast in the distal radioulnar compartment or at the site of the triangular cartilage indicates a tear (
Fig. 7.29).
Until recently, arthrography has been the procedure of choice for the evaluation of TFCC. Currently, it is generally believed that in the diagnosis of TFCC abnormalities, particularly when using eight-channel phased-array extremity coil, MRI approaches and frequently surpasses arthrography in accuracy. The advantage of MRI is its noninvasiveness and ability to image the entire fibrocartilage substance, whereas arthrography is limited to the evaluation of the surface of this structure only. On coronal T1-weighted MR images, the normal TFCC appears as a biconcave band of homogeneous low signal intensity extending across the space between the distal ulna, the medial aspect of distal radius, and the triquetrum and lunate bones (
Fig. 7.30, see also
Fig. 7.8). Tears of the TFCC manifest as discontinuities and fragmentation of this structure. The torn fibrocartilage becomes irregular in contour and is interrupted by high signal intensity areas on T2-weighted images (
Fig. 7.31). However, one of the studies published by Haims and colleagues, questions the sensitivity of MRI in diagnosing peripheral tears of the triangular fibrocartilage. In this respect, the authors reported the sensitivity of MRI of only 17%, with a specificity of 79%, and accuracy of 64%.