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Distal radius fractures are not a single injury that can be treated with one method of management.
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Patterns of injury should be characterized in the context of the type of patient, the mechanism and principal direction of injury, the fragmentation pattern, any associated pathology, and the presence of osteoporosis.
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No single method is uniformly effective for all fractures.
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Recent advances in both the evaluation and management of distal radius fractures continue to improve our understanding of the nature of these injuries as well as the expected outcomes.
Blocking a fall with the outstretched hand is a primitive reflex that appears in infancy just before walking age and persists throughout life. When the parachute reflex is combined with activities that challenge gravity, conditions that interfere with balance, or structural pathology that weakens bone, the result may be an unhappy patient with a fractured distal radius.
Epidemiology
Fractures of the distal radius are among the most common osseous injuries of the musculoskeletal system. Vogt and colleagues examined the incidence and distribution of distal radius fractures treated at four separate medical centers in the United States over a 10-year period and found an overall incidence of 7 per 1000 person-years. In this sample population, 27% of these fractures presented as an intra-articular pattern and 73% as an extra-articular pattern. A decreased bone mineral density increased the relative risk of fracture to 1.8, whereas a history of falls increased the relative risk to 1.6. If the injury occurred in a female with diabetes, the rate of intra-articular fractures nearly doubled. Chung and colleagues, in a review of nearly 1.5 million fractures recorded by the National Hospital Ambulatory Medicare Care Survey, determined that 44% of fractures involved the distal radius; of these, 30% occurred from an injury at home and 47% were caused by accidental falls.
Several studies demonstrate that both the number and incidence of distal radius fractures have been steadily increasing over the past several decades and have varied in relation to gender, age, and ethnicity. Hagino and colleagues in Japan determined that the incidence of fractures in women increased from 165/100,000 in 1986 to a rate of 211/100,000 in 1995 and that the incidence was lower in Japanese persons than in whites. Studies by Solgaard and Petersen and Jonsson and colleagues in Sweden also confirm an increase in the incidence in wrist fractures over the past several decades. Thompson and colleagues in the United Kingdom found a female-to-male ratio of 3.9:1, with a premenopausal risk in women of 10/10,000 that increased to 120/10,000 in women older than 85. In contrast, men younger than the age of 65 showed a reduced risk of only 10/10,000 that increased to only 33/10,000 in men older than the age of 85. These authors also noted an increase in the incidence over the past 30 years. Nguyen and colleagues, in a prospective study on osteoporosis in Dubbo, Australia, studied individuals older than 60 years of age and found an incidence of distal radius fractures of 34/10,000 in men compared with 125/10,000 in women.
In younger patients, recreational activities may often influence the incidence and pattern of distal radius fractures. Distal radius fractures can occur with any contact sport including basketball, soccer, skiing, and football. Skateboarding and rollerblading are activities that are particularly prone to fractures of the distal radius. The recent increase in popularity of snowboarding has added yet another recreational sport as a consistent source of distal radius fractures in the young active adult population. In a study of snowboarders who sustained distal radius fractures, Matsumoto and colleagues reported that these fractures were more often seen in those with less experience; inexperienced snowboarders accounted for 42% and intermediate snowboarders for 48%. In beginners, extra-articular fracture patterns were more common injuries and were usually caused by a simple fall. Intermediate snowboarders, however, more likely had comminuted intra-articular fracture patterns that were caused from a failed jump. In this study, the side opposite to the rider’s preferred position of stance was more commonly affected, with a higher frequency of injury associated with the technique of opposite-side edging.
Classification
Classification of distal radius fractures is helpful only if it provides meaningful information that improves our understanding of the injury or helps influence the course of treatment. A classification system should clarify differences in natural history and prognosis as related to differences in the patterns of injury. In addition, a useful classification system that is able to distinguish the unique personalities of various patterns of injury can provide insight as to why a particular type of treatment may work well in one fracture and fail in another. Most classification systems are based on parameters such as patient age, patient activity, fracture geometry, mechanism of injury, direction of displacement, and the number and type of fragments. In addition, the local tissue environment, mechanism of injury, and associated pathology are additional parameters that may be relevant to define the type of fractures. An accurate and consistent classification system for distal radius fractures is essential to generate meaningful scientific evaluations in the clinical setting and enable comparison of data across institutions, especially because conclusions from research data implicitly assume that a homogeneous population sample was examined in each group. Unfortunately, many previous scientific investigations on distal radius fractures may be flawed simply because the author included widely disparate patterns of injury in a single study group.
Initial descriptions of distal radius fractures during the early part of the 19th century by individuals such as Colles, Poutreau, and Dupuytren were an intuitive leap from the prevalent belief at the time that these injuries were caused by a dislocation of the carpus. Although these initial authors grouped distal radius fractures as a single entity and type of injury, it should be remembered that these early descriptions predated the discovery of x-rays by nearly 80 years. Unfortunately, for many surgeons, it is an unfortunate legacy that this tendency to consider all Colles fractures as a single, homogeneous injury pattern persists to this day and may remain one of the greatest impediments to appropriate treatment.
In contrast to these limited early descriptions, there are few areas of skeletal anatomy that over the past century have generated as many different classification systems of patterns of injury as fractures of the distal radius. Classification systems by authors such as Lidstrom, Nissen-Lie, Older, Destot, Gartland and Werley, and Frykman sought to distinguish differences in fracture patterns based on the amount of displacement, comminution, involvement of the distal radioulnar joint, and involvement of the radiocarpal joint. Later classification systems by authors such as McMurty, Melone, and Cooney further advanced our knowledge, with particular focus on fragmentation of the dorsal and palmar joint surfaces in conjunction with the degree and direction of displacement.
The Comprehensive Classification of Long Bone Fractures (AO) is a global system that was designed for classification of extremity fractures in general and includes classification of fractures of the distal radius as a subcategory. This classification system is often designated as the preferred description when reporting clinical data. The AO classification system separates distal radius fractures into three basic types: extra-articular fractures (type A), partial articular fractures (type B), and intra-articular fractures (type C). Type A fractures are subdivided further into three groups that include isolated fractures of the ulna (A1), simple extra-articular fractures of the radius (A2), and multifragmentary extra-articular metaphyseal fractures of the radius (A3). In a similar manner, type B fractures are grouped into medial or lateral shear fractures of the radius (B1), dorsal rim fractures of the radius (B2), and volar rim fractures of the radius (B3). Finally, type C fractures, complete articular fractures of the radius, are subdivided into three major groups that include simple articular fractures (C1), simple articular fractures with metaphyseal comminution (C2), and combined multifragmented articular fractures of the radius (C3). Each of these 9 groups is subdivided further into 3 subgroups according to specific features, producing 27 distinct subgroups; the addition of ulnar pathology to each individual subgroup can result in 144 potentially different combinations of injury.
Although currently this classification system is often designated arbitrarily as the preferred method for reporting clinical data, the utility of this system has been called into question. In a study that examined clinical use of the AO classification system, the reliability and accuracy of this classification when evaluating radiographs of distal radius fractures was studied. Consistency between different surgeons was found to be limited only to determination of the three basic fracture types, namely, extra-articular (type A), partial articular (type B), and intra-articular (type C) fractures. Consistency seemed to be improved by the clinical experience of the surgeon. In addition, when the same observer was asked to separately evaluate the radiographic studies of the same injury at two separate points in time, consistency remained limited to classification of the three basic types. Despite the fact that this system is the most widely used method for reporting clinical data of distal radius fractures, these studies question the validity of the AO classification beyond the three basic fracture types.
The classification system of distal radius fractures by Jupiter and Fernandez categorizes distal radius fractures according to the mechanism of injury. With this method of classification, fractures are separated into five basic groups. Bending injuries produce the extra-articular fracture patterns characterized by an intact radiocarpal joint surface. Shear fractures make up the second group of injuries, characterized by osseous failure along one side of the articular surface of the distal radius caused by shearing loads that are the result of dorsal, palmar, or radial translation of the carpus. Shear fractures include injuries that previously were described under the eponyms of Barton’s, reverse Barton’s, and Chauffer’s fractures. The third group of injuries, axial loading fractures, are caused by direct impaction of the carpus longitudinally against the articular surface of the distal radius resulting in either simple or complex articular fractures depending on the magnitude of applied load. Carpal avulsions make up the fourth group, characterized as predominantly ligamentous injuries of the carpus in which osseous avulsion of the distal radius has also occurred. Finally, high-energy injuries caused by mechanisms such as vehicular trauma or falls from an elevated height make up the last group and can be identified by the extensive comminution of the distal radius and ulna, disruption of the distal radioulnar joint, and fracture extension into the forearm. Often high-energy injuries are associated with extensive soft-tissue trauma that may dominate management of these extensive injuries.
Extra-articular fractures that dorsally displace often have different mechanisms of injury and different biomechanical components of instability than extra-articular fractures associated with palmar displacement. Similarly, shear fractures that involve the dorsal rim often have a different mechanism of injury and approach to treatment from that of shear fractures that involve the palmar rim or radial margin. Because of this, a refinement of the mechanism-based classification system has been proposed that distinguishes dorsal and palmar extra-articular fractures, as well as dorsal, palmar, and radial shear fractures. In this modified classification system, axial load injuries are also divided into two basic groups. One group is the relatively common, simple three-part fracture consisting of a dorsal ulnar corner fragment along the sigmoid notch and a second large articular fragment. The second axial loading group is the more complex polyarticular fracture, which may include radial column, free intra-articular, and volar rim fracture elements with or without ulnar column disruption ( Table 69-1 , online).
| Mechanism of Injury | Fracture Personality |
|---|---|
| Bending | Dorsal extra-articular |
| Volar extra-articular | |
| Shear | Dorsal shear |
| Volar shear | |
| Radial shear | |
| Axial load | Simple three part |
| Complex articular | |
| Complex articular + distal radioulnar joint instability | |
| High energy | Complex articular + shaft extension |
| Carpal avulsion | Carpal dislocation with osseous avulsion |
Medoff and Rickli and Regazzoni independently developed a description of intra-articular injuries of the distal radius according to a columnar concept. Medoff stressed the importance of the radial column, a pillar of support behind the scaphoid facet and formed by the three orthogonal surfaces of cortical bone along the dorsal, radial, and palmar surfaces that make up the normal lateral support structure of the distal radius. In fractures that disrupt the radial column, the radial column migrates proximally, resulting in loss of length of the radial border. The terminal insertion of the brachioradialis tendon on the unstable distal fragment may contribute to this loss of radial length. With loss of carpal support by the radial column, secondary migration of the carpus occurs, resulting in further overload to the lunate facet. In this situation, reducing and stabilizing the central portion of the joint surface often may be simplified by first restoring length back to the radial column. Like a car jack lifting a car frame to change a tire, reduction of the radial column allows maintenance of radial length across the carpus, thereby unloading the middle column. Fractures that are characterized by extensive comminution of the radial column into multiple small pieces often may exhibit extreme instability because the proximal carpal row has lost radial column support. Rickli and Regazzoni added to this concept further, describing the importance of the central column, which is formed by the lunate facet and lateral border of the distal radius, as well as the ulnar column, which includes the distal ulna, triangular fibrocartilage complex, and distal radioulnar joint. Disruption between the middle column and ulnar column can lead to dissociation and instability of the distal radioulnar joint. This three-column concept is useful to identify and describe abnormal relationships within the three major load-bearing areas of the joint.
The fragment-specific classification is used to describe the components of articular involvement in the case of intra-articular fracture patterns ( Fig. 69-1 ). The fragment-specific classification system identifies five possible major fracture elements: (1) radial column, (2) dorsal wall, (3) ulnar corner, (4) volar rim, and (5) free intra-articular. In this system, any particular intra-articular fracture is described according to which subset of these five basic fracture components is present. Analysis of the ulnar column injury and metaphyseal void is added to provide a comprehensive overview of any particular injury. By determining the specific components of a complex articular fracture of the distal radius, the surgeon is better prepared to determine the approach to treatment and to assess the adequacy of reduction.
Classification of distal radius fractures is incomplete without consideration of the type of patient. In general, there are four major demographic groups, with individual characteristics and expectations specific to each group: (1) pediatric, (2) young adult, (3) active adult, and (4) senility fractures. Pediatric fractures are injuries that occur in bones with open epiphyseal plates. In this group, concerns include growth plate disturbance, plastic deformation of bone, patient compliance, and compartmental problems. Because of the structural and mechanical differences of the immature musculoskeletal system, the approach to management of pediatric fractures is quite different from that for other age-groups; many of these fractures are successfully treated with closed methods of management. Fractures that occur in the second group of patients, young adults, typically involve individuals who have a normal skeletal structure and an active lifestyle. Because these individuals frequently have high demands, they may be less tolerant of fractures that are malreduced or outcomes that have some residual loss of function. Younger active patients are much more likely to have associated intracarpal pathology such as scapholunate ligament tears; this risk appears to be increased in the context of preexisting positive ulnar variance and intra-articular fracture patterns. The active adult population typically has somewhat different concerns regarding the level of physical activity and time lost from work; in addition, this group may have some mild degree of osteoporosis. Finally, senility fractures in patients with limited functional demands are often associated with other systematic pathology as well as significant osteoporosis. For each of these basic groups, the patient expectations and functional requirements may be quite different; what may be regarded as a satisfactory outcome for one group may be completely unacceptable for another.
Radiographic Evaluation
Classification of distal radius fractures is largely dependent on accurate interpretation of the patient’s radiographs. Recently, modalities such as computed tomography, 3D reconstruction of CT, and MRI have been major technical advances that may provide more detailed assessment of these injuries. In addition, correlation of these advanced methods of imaging with careful examination of findings on plain radiographs has significantly improved our ability to analyze and recognize important elements of structural anatomy and details regarding pathology that have been largely overlooked in the past.
The minimal radiographic study for evaluation of distal radius fractures should include both posteroanterior and lateral views. The 10-degree lateral and oblique radiographs can often provide additional useful information to these basic views. Because radiographs are a simple two-dimensional representation of a complex 3D solid object, creating a mental image and model of the fracture requires careful analysis of radiographs of reasonably good quality. Complex fractures often cause marked distortion of normal anatomic features, resulting in radiographic images that are difficult to interpret. In these situations, clarification of the nature of the injury is often no more complicated than simply getting a second set of radiographs after a closed reduction.
Examination of radiographs should include identification of the carpal facet horizon, the radiodense line that runs transversely across the distal end of the radius on the posteroanterior view, and correlation of this structure with the tilt of the articular surface on the lateral-view radiograph. If the articular surface is tilted in a volar direction on the lateral view, this landmark corresponds to the volar rim of the lunate facet. If the articular surface is tilted in a dorsal direction on the lateral view, this landmark corresponds to the dorsal rim of the lunate facet. This simple correlation of the tilt of the joint surface on the lateral view with identification of the carpal facet horizon on the posteroanterior view helps to determine whether the palmar or dorsal rim of the sigmoid notch is involved and may potentially affect the type of treatment.
The joint interval of the radiocarpal and distal radioulnar joints should also be carefully examined. Normally, the radiocarpal joint interval measures 2 mm and is congruent on both posteroanterior and lateral views. On the lateral projections, the arc of curve of the lunate should match the corresponding arc of curve of the distal radius and show a concentric, uniform joint interval. A nonuniform joint interval, nonconcentric arc of curve, or widening of the dorsal-to-palmar distance between the dorsal rim and palmar rim of the articular surface on the lateral view indicates intra-articular disruption of the articular surface and a potentially nonanatomic reduction.
The joint interval at the distal radioulnar joint is typically 1 to 2 mm. Ideally, this joint interval is assessed in a position of neutral forearm rotation because apparent widening of the distal radioulnar joint interval normally occurs with radiographs that are taken with supination of the forearm. On a neutral or pronated view, however, excessive separation of the sigmoid notch from the ulnar head indicates disruption of the ligaments across the distal radioulnar joint and often pathology in the triangular fibrocartilage complex. Failure to close a significantly widened distal radioulnar joint with reduction or internal fixation may contribute to dysfunction of forearm rotation or stability at this joint.
Similarly, fractures through the ulnar styloid should be identified because they can have an adverse effect on the stability of the distal radioulnar joint. The presence of excessive radial translation should be assessed because this may indicate instability at either the radiocarpal or distal radioulnar joint. Distal radioulnar joint instability may occur without obvious signs of osseous involvement of the distal ulna if there is a purely ligamentous injury of the ulnar column. In such cases, radial translation of the carpus on a radiograph may be one sign that may suggest this type of instability.
With the hand in a position of 0 to 15 degrees of dorsiflexion, the center of the base of the capitate is normally aligned on the lateral-view radiograph with a line extending from the volar shaft of the radius. Significant displacement of this carpal alignment may be a subtle sign of incomplete articular reduction and can occur with fractures that displace in either a dorsal or palmar direction. Because dorsal translation of lateral carpal alignment is also seen with dorsal segmental intercalated instability from pathology of the scapholunate ligament, this etiology should also be considered.
The teardrop is a landmark on the lateral radiograph that is easily overlooked. Formed by the confluence of the distal flare of the radial shaft, the distal radial ridge, and the volar rim of the lunate facet, the teardrop represents an important part of the volar rim and is a major contributor to structural support of the carpus. Normally, a line drawn down either the center of the teardrop or parallel to the subchondral bone of the volar rim of the lunate facet subtends an angle of approximately 70 degrees to the longitudinal axis of the radial shaft. Fractures that involve a separate teardrop fragment are nearly always unstable and may displace either palmarly into the volar soft tissues or rotate into hyperextension with subluxation of the carpus dorsally and abnormalities of the lateral carpal alignment. The latter injuries are characterized by depression of the teardrop angle to less than 45 degrees ( Fig. 69-2 , online).
