Epidemiology

Distal radius fractures, first described by Abraham Colles1 in 1814, are among the most common fractures seen in emergency rooms. They account for 20% of all the fractures treated in the emergency departments and comprise 74.5% of all fractures distal to the elbow.2,3 Overall, distal radius fractures account for approximately 200,000 fractures per year in the United States.4 They account for 0.7% of all work-related injuries, 3% of all upper-extremity injuries, and 10% of all work-related fractures.5,6 The classic Colles fracture, defined as a dorsally displaced fracture of the lower end of the radius within 1.5 inches of the joint, accounts for the majority of distal radius fractures. Smith fractures, described by Robert William Smith, are volarly angulated fractures. Barton′s fracture, which are intra-articular shearing fractures of the distal radius with dislocation of the radiocarpal joint, account for a small subset of fractures but are important injuries that cannot be overlooked. The volar Barton′s fracture is more common than the classically described dorsal shear fracture. Radial styloid fractures also account for a small but important percentage of distal radius fractures.7,8

There is a bimodal distribution of fractures of the distal radius, with two peaks occurring—one between the ages of 6 and 10 years and the other between the ages of 60 and 69 years. A large series evaluated over 4,000 consecutive acute fractures of the distal radius presenting to a large trauma unit.9 Important findings included that most patients were functional before their injury, with 87% of the elderly being independent for all the activities of daily living. This emphasizes the need to return patients with these injuries to their preinjury level of activity. The mechanism of injury is usually a fall on an outstretched hand. The simplest fracture mechanism is a bending fracture, typical in an elderly woman, that usually leaves the articular surface intact but creates a fracture in the metaphysis. Distal radius fractures may be intra-articular by extending into either the radiocarpal or the distal radioulnar.9,10 Over 50% of the fractures in the Edinburgh series, previously mentioned, were AO type A3.2 (extra-articular with metaphyseal comminution) or C2.1 (simple articular with metaphyseal comminution).9

Anatomy

The distal end of the radius has two concave articular surfaces that engage with the proximal carpal row—the scaphoid fossa and the lunate fossa. The scaphoid fossa is elliptical and thus does not tolerate carpal malalignment well, whereas the lunate facet is spherical and thus is more tolerant of lunate flexion or extension. There is a ridge between these two facets that may be pronounced in some individuals. The sigmoid notch is concave and articulates with the ulnar head and makes up a portion of the distal radioulnar joint (DRUJ) (Fig. 19.1). The sigmoid notch is flatter, with a greater radii of curvature than the ulnar head; thus, DRUJ motion involves rotation and translation. The triangular fibrocartilage complex originates from the ulnar aspect of the radius and attaches to the base of the ulnar styloid. The thickened dorsal and volar margins of the triangular fibrocartilage form the dorsal and ulnar radioulnar ligaments.11 Radial deformity, especially radial shortening, can alter the kinematics of both the radiocarpal joint and the DRUJ.12,13

The metaphysis of the radius is composed primarily of cancellous bone and is located 2 to 3 cm proximal to the radiocarpal joint. At the metaphyseal flare, the thickness of the cortical bone decreases and the amount of cancellous bone increases, forming a zone predisposed to fracture.14 The volar surface is concave, whereas the dorsal surface is convex. The volar cortex is thicker, and thus easier to align during fracture reduction, whereas the dorsal cortex is thin and often multifragmented from fracture. The radiocarpal articular surface has 10 to 14 degrees of volar tilt, and approximately 22 degrees of ulnar-facing inclination in the frontal plane. The distal radius also makes up a portion of the floor of the carpal tunnel volarly, which has implications with regard to median nerve dysfunction and complications.15

Force transmission from the hand to the arm occurs through the wrist. In a neutral axis, the radiocarpal joint receives 80 to 85% of the load, whereas the ulnocarpal joint receives the remaining 15 to 20%.13 The fraction of force transmission may vary or be altered with changes in ulnar variance or in dorsal tilt of the radius.16 An ulnar-positive deformity of 2.5 mm results in 42% of the load being born by the distal ulna, whereas a 2.5-mm negative alignment of the distal ulna decreases its received load to 4.3%.16 Numerous biomechanical investigations have shown that dorsal malunions of the distal radial metaphysis can effect changes in carpal alignment, resulting in adaptive dorsal carpal instability.12,13,15,16 The load is also displaced dorsally and concentrated in a smaller area, which theoretically could accelerate joint arthrosis. Dorsal malunions often result in decreased grip strength, which may be a result of pain or the decrease in the functional length of the tendons crossing the wrist resulting from radial shortening.17–19

The dorsal radiocarpal ligaments originate on the radius just ulnar to Lister′s tubercle. They extend from the radius to the triquetrum to form the dorsal radiocarpal ligament (DRC) and from the triquetrum to the scaphoid to form the dorsal intercarpal ligament (DIC). The dorsal ligaments expand with volar flexion and can become contracted with injury. The volar radiocarpal ligaments originate from the volar metaphysis of the radius 5 mm from radiocarpal joint. These ligaments are often the site of small avulsion fractures from the distal radius.20–22

The extensor and flexor tendons of the wrist traverse the distal aspect of the radius to insert onto the metacarpals dorsally and phalanges volarly, respectively. Only the brachioradialis tendon inserts onto the distal aspect of the radius. It often acts as a deforming force on the fracture fragments that may be worsened with the chronicity of the injury.23

Radiographic Evaluation

Preoperative radiographic evaluation is of vital importance to successful assessment of fracture characteristics and optimal treatment outcomes. Plain radiographs should include a posteroanterior (PA), lateral, and oblique radiograph of the distal radius at injury and then after closed reduction and splinting. Proper orientation of the plain films is critical, as malrotation will alter the apparent radiographic parameters.24 The PA zero-rotation radiograph (Fig. 19.2a) should be tangential to the DRUJ, and determines radial shortening and inclination, and can assess articular step-off. The PA view should be taken with the shoulder abducted, the elbow flexed to 90 degrees, and the forearm in neutral rotation. This standardizes the assessment of ulnar variance, which may help in deciding on the appropriate treatment.

A true lateral view shows the pisiform to lie between the volar lip of the scaphoid and the volar cortex of the capitate. Angular tilt of the radius and proper carpal alignment on the radius is detected from this view (Fig. 19.2b). A fossa-lateral view is shot at a 20-degree angle where the beam is directed from distal radially to the proximal ulnarly. This view clearly demonstrates the articular surface by removing the radial styloid from the projection (Fig. 19.3). This view has also been shown to better assess the dorsal tilt and articular congruence than does a traditional lateral view.25 The oblique radiograph is particularly helpful in identifying displacement of fractures of the lunate facet. This view profiles the portion of the dorsal ulnar cortex, which supports the dorsal lunate articular facet, and also the dorsal margin of the sigmoid notch.

The standard normal radiographic parameters of the distal radius include a radial inclination of 22 degrees (range, 13–30 degrees), a radial length of 12 mm (range, 8–18 mm), and an average volar tilt of 12 degrees (range, 1–21 degrees).26 For complex articular fractures a computed tomography (CT) scan is helpful in detecting the location of fracture fragments, in determining the degree of comminution, and in assessing the subtle subluxations of the radiocarpal and DRUJ. The scan should be done after closed reduction of the fracture and should include two-dimensional reconstruction views in the frontal and sagittal planes. At times, a three-dimensional reconstruction provides additional information. It is important to recognize that distal radius fractures can be intra-articular fractures not only at the radiocarpal joint but also at the DRUJ. Information gleaned from the CT scan can aid in determining the appropriate surgical approaches and the specific requirements for fracture fragment reduction.

Classification

Historically, there have been many classification systems for fractures of the distal radius. In 1951, Gartland and Werley27 based their classification on the presence, but not the extent, of fragment displacement, and on the presence of intra-articular involvement. The Frykman15 classification described in 1967 is based on the distinction between extra- and intra-articular fractures in the presence of distal ulna fracture involvement. This classification is one of the first to regard involvement of the radiocarpal joint and of the distal radioulnar joint as distinct. The limitations of the Frykman classification are that it does not describe the amount of fracture displacement or the degree of fracture comminution. The Melone28 classification, introduced in 1984, is one of the first to provide a description of the important component parts of the distal radius fracture. It importantly terms the “medial complex” as the portion of the sigmoid notch and lunate facet that may be fragmented and split into volar and dorsal fragments. The AO/Orthopaedic Trauma Association (OTA) classification system is complex, as it has 27 categories. It is difficult to use clinically, but it serves as a useful guide in research and comparative studies. A mechanistic classification developed by Jupiter and Fernandez29 is helpful in describing the amount of energy imparted to, and the instability of, the various fractures (Fig. 19.4). The mechanisms, moving from simple to more complex, include bending, shear, compression, avulsion, and combined injuries.22,29

Treatment Closed Treatment

Closed treatment of distal radius fractures is still an acceptable option for appropriate fractures. Traction and ligamentotaxis is used to reduce the fracture fragments. The radiocarpal ligaments are attached to the rim of the metaphysis, and thus minimal reduction of impacted articular fragments is usually achieved with closed reduction. Fractures must be maintained in an acceptable alignment to ensure adequate functional results. Radiographic parameters that are deemed unacceptable are articular incongruity greater than 2 mm (step-off is more important than gap), dorsal tilt past 10 degrees, volar tilt greater than 20 degrees, radial inclination less than 15 degrees, ulnar positive variance of greater than 5 mm, and any carpal subluxation.30

It is often difficult to determine which fractures are amenable to closed reduction. Two different scoring systems that attempt to evaluate stability of distal radius fractures were evaluated in a study of 105 patients.31 In this prospective review, it was found that both scoring systems underestimated the degree of fracture instability. In a different study analyzing 71 elderly patients with extra-articular distal radius fractures treated by closed means, the signs of early (1 week) and late (6 weeks) in-stability were evaluated.32 The investigators found that radial shortening and volar tilt greater than 20 degrees were the best predictors of early instability, and that radial inclination less than 10 degrees, age older than 65 years, and dorsal tilt greater than 20 degrees were predictive of late instability.

The specific type of immobilization of closed fractures is often debated. In a meta-analysis of a total of 404 patients with distal radius fractures, the technique of closed reduction and immobilization showed no significant difference in final radiographic alignment or complication rate.33 This included the type of traction (manual traction with or without finger traps), rotational position of splinting (supination, pronation, neutral), or material used for immobilization.

The question of short- or long-arm immobilization is often debated. In a prospective randomized trial evaluation of the closed treatment of distal radius fractures, a sugar-tong splint and a radial gutter splint were compared. Both groups exhibited similar rates of lost reduction, and the short-arm immobilization group had significantly better functional outcome scores.34 While taking the varied clinical data in consideration, with an unstable distal radius fracture in a young patient, immobilization above the elbow does minimize rotation and deforming forces at the fracture site.

In treating comminuted fractures of the distal radius in the elderly with closed reduction and cast immobilization, reduction is often lost. A study evaluating 60 elderly patients who underwent closed reduction cast immobilization demonstrated that 88% lost fracture reduction. Of the 53 fractures that lost reduction, the majority of them (75%) did so within 1 week of initial reduction.35

Surgical Treatment

Indications

Radiographic signs that should alert the surgeon that the fracture is likely unstable and that closed reduction may be insufficient include the following:

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  Dorsal comminution greater than 50% of the volar-dorsal dimension of the radius

  
  
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  Palmar metaphyseal comminution

  
  
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  Initial dorsal tilt greater than 20 degree

  
  
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  Initial displacement (fragment translation) greater than 1 cm

  
  
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  Initial radial shortening more than 5 mm

  
  
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  Intra-articular disruption

  
  
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  Associated ulna fracture

  
  
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  Severe osteoporosis26,36

Surviving the Night

Distal radius fractures present within a spectrum of severity. The injury pattern ranges from low-energy injuries that can be treated closed, to high-energy injuries that have associated soft tissue injuries and higher rates of complications. It is crucial to recognize the differences in these types of injuries. Associated soft tissue injuries that are of concern with distal radius fractures include median nerve involvement, acute carpal tunnel syndrome, compartment syndrome, ligamentous injury, and carpal dislocations. Neuritis of the median nerve is often seen with distal radius fractures, and it is crucial to ensure that it is not progressive. The nerve may be irritated by contusion at injury or during reduction, affected by the hematoma block, compressed by hematoma in the carpal tunnel, or involved in a compartment syndrome of the forearm.

If paresthesias are present in the median nerve after a distal radius fracture, the patient should be evaluated in a systematic fashion. First the dressing and splint should be examined to ensure that the dressing is not excessively tight and the position of wrist flexion is not beyond 20 degrees. After these offending agents have been removed, the neuritis should improve. The important factor is that the paresthesias lessen over time and that there is no motor involvement. If this does not occur in a short time, the dressing should be removed and the soft tissues inspected. If there is evidence of acute carpal tunnel syndrome or compartment syndrome, then urgent release should be performed. If possible, this should be combined with appropriate fixation of the distal radius fracture.

Open fractures of the distal radius are not uncommon. If a distal radius or ulnar injury is an open fracture, then acute surgical treatment is required. The open wound should be extended in anticipation of the open surgical approach that is necessary for appropriate fixation. If the surgeon is experienced in these techniques, then definitive fixation can be performed. If the fracture is extremely complex and beyond the surgical skills of the treating physician, then irrigation and debridement and external fixation is appropriate. Care should be taken to place the radial shaft external fixator pins sufficiently proximal to avoid any encroachment on eventual plate application.

Infrequently, a compartment syndrome of the forearm may be associated with a distal radius fracture. This requires urgent fasciotomies and appropriate treatment of the distal radius fractures. A carpal tunnel release should be combined with incisions proximally into the volar forearm. The carpal tunnel incision is in line with the ring finger ray and then the incision is curved ulnarly at the wrist crease. Over the volar forearm the incision is gently curved and then is stopped at the ulnar aspect of the antecubital fossa at the biceps tendon. If the swelling is in the upper arm, a Z-shape is made in the incision and it is carried proximally into the arm. The superficial and deep volar forearm compartments must be released as well as the lacertus fibrosis in the arm. Through the volar forearm incision, the mobile wad (brachioradialis and extensor carpi radialis longus [ECRL] and extensor carpi radialis brevis [ECRB]) muscles can be released. If the dorsal forearm still has swelling, then the extensor muscles are released through a longitudinal incision.

Principles and Surgical Approaches for Internal Fixation

Recent trends have noted a dramatic increase in the incidence of operative treatment of these fractures with plating, and an associated decrease in the use of external fixation.37 The efficacy of plating has been demonstrated in the literature and has shown some advantages over non-operative treatment and external fixation in terms of early return to function and less malunions. Newly designed dedicated hardware options specific to the distal radius have aided the stabilization of these fractures, but the principles of anatomic reduction still remain. When the injuries and fracture patterns become increasingly complex, newer fixation options enable a more accurate reconstruction than in the past. Today, advances in technology have enabled multiple approaches; lower profile plating; and rigid, fragment-specific fixation to address even the most complex fracture patterns.

When considering how to restore anatomic alignment in complex distal radius fractures, it is important to consider the two separate joint surfaces (the radiocarpal and distal radioulnar); the three columns of the distal radius (the radial, intermediate, and ulnar columns); and the distal ulna and triangular fibrocartilage complex (TFCC). The principles and goals of fracture fixation at the wrist are anatomic reduction of the articular surface; proper alignment of the joint surface with regard to length, tilt, and inclination; and stable fixation that will enable early function and range of motion of the fingers and adjacent joints.

Preoperatively, the fracture pattern must be evaluated to determine the appropriate method of fixation. It is critical to assess if the fracture involvement is extra- or intra-articular. The articular fracture may involve the entire joint surface or be a partial articular shear fracture. The approximate number of fragments must be estimated, as greater comminution may require multiple plates and/or multiple surgical approaches. If there is a large amount of dorsal comminution, a supplemental dorsal approach may be needed. The medial facet (intermediate column) can be split into volar and dorsal portions that can displace in separate directions. The columns involved should be noted. In general, the intermediate column should be addressed first and is the “keystone” to the radius as it contains both the radiocarpal and radioulnar joint surfaces. Severe articular impaction may necessitate bone grafting when the fragments are reduced into their appropriate locations. Once preoperative planning is completed, several surgical approaches can be utilized to achieve ideal exposure access to specific fracture fragments.

Volar Approaches

Video 19.1 Volar Plating Distal Radius Fracture

Excellent access to the distal radius can be achieved via the distal Henry or flexor carpi radialis (FCR) approach. With the advent of precontoured locked plates, designed to be applied to the volar distal radius, the volar approach has become the utilitarian approach for the majority of distal radius fractures (Fig. 19.5). The incision is made between the radial artery and the FCR tendon. In contrast to the classic Henry approach to the volar forearm, the radial artery is retracted radially. The deep interval is through the floor of the sheath of the FCR tendon. Care should be taken not to dissect ulnar to the FCR as the palmar cutaneous branch of the median nerve is in this interval.38 The pronator quadratus and flexor pollicis longus (FPL) muscle bellies are elevated and retracted radial to ulnar and the fracture is exposed39 (Fig. 19.6). The dissection of soft tissue off the distal radius must not be extended to the most distal end of the volar radius, as this would release the volar radiocarpal ligaments and induce wrist instability.39 Repair of the pronator quadratus is helpful for soft tissue cover of the plate, but its functional importance is debated. A recent comparative study did not find significant differences in function or complication rate in patients with and those without repair of the pronator muscle.40

A volar plate should be applied to the radial shaft in an appropriate proximal-distal position in order to span the fracture and to ensure that the distal aspect of the plate is proximal to the “watershed line” of the distal radius. The line has been described by Orbay,41 and is the volar-most cortical surface of the distal radius and actually extends more distally on the ulnar aspect than on the radial. Plates more distal to this line can irritate flexor tendons and the median nerve. Particular attention should be paid to avoiding plate prominence at the radial styloid, as irritation of the FPL tendon can occur. It is usually helpful to release the brachioradialis tendon from the radial styloid for fracture reduction. This can be done by complete elevation from the radial styloid, or it can be released in a step-cut method. Repair of this tendon after fracture reduction has been advocated, but is not necessary from a functional aspect (Fig. 19.7).

Comminuted distal radius fractures can be reduced and stabilized with a plate through the volar approach. The volar cortex is generally thicker than the dorsal cortex and can be used as guide for fracture correction of both angulation and rotation. Dorsal fragmentation can often be reduced with flexion of the distal radial fragments to the plate. In general, screw fixation should begin with the ulnar-sided screws to ensure that screws do not penetrate the radiocarpal joint. If the distal fracture fragment needs to be pulled toward the plate, a nonlocking screw can be inserted first, followed by locking screws in the adjacent holes. The initial screw can then be exchanged for a locking screw if the initial purchase is poor. It is important that the screws not be overly long, as dorsal tendon irritation and rupture may occur. After measuring the length, subtract 2 to 3 mm, as the dorsal cortex provides little purchase (Fig. 19.8). With fracture fragment elevation there is often a defect in the metaphyseal cancellous bone. If needed, bone grafting can be achieved from the volar side through the fracture gap or after pronation of the radial shaft out of the wound.42

At times, a volar plate cannot adequately reduce the radial styloid fragment if it is severely displaced or malrotated. In these instances, a radial styloid buttress plate can provide the reduction force necessary to reduce and stabilize this fragment. The radial styloid can be addressed and plated from the volar Henry approach. After releasing the brachioradialis insertion distally, the first dorsal compartment is identified and partially released to enable plate placement. The plate is stabilized on the radial shaft proximal to the first dorsal compartment, and the fracture is secured distal to it. The distal screws must be targeted around the volar plate screws, and are either bicortical or unicortical and locking.

An alternative approach for fracture stabilization is the ulnar extensile approach to the distal radius. The surgical interval is between the ulnar neurovascular bundle and the carpal tunnel contents. The approach ends at the wrist crease if fracture fixation alone is needed. This exposure is ideal to address complex fractures of the volar-ulnar corner of the radius, and it provides access to the sigmoid notch, the DRUJ, and the ulnar column. A plate can be easily applied through this approach, but exposure of the radial styloid is not as broad as the FCR approach (Fig. 19.9). This approach is also ideal for distal radius fractures associated with median nerve injury, as it can be easily extended into a carpal tunnel release and the median nerve can be examined through its entire course (Fig. 19.10).

Tips and Tricks

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  The distal radius is triangular in the axial plane; thus, screws that may appear within the bone on a straight lateral view may actually be out of the dorsal cortex by several millimeters.

  
  
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  Each distal radius fracture should be evaluated for the most appropriate approach. Fractures that are better treated with an ulnar extensile approach are those with a comminuted volar-ulnar corner fragment; those that involve injury to the median nerve; and those associated with carpal dislocation or compartment syndrome.

  
  
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  Provisional reduction of distal radius fractures treated with volar plating can be first obtained with multiple Kirschner wires (K-wires) placed through holes in the plate.

  
  
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  Reduction of dorsally displaced fractures that are to be fixed with a volar plate requires hyperflexion of the distal fragment to the plate. Compression of the distal fragment to the plate is required before pin or screw fixation.

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