Additional videos related to the subject of this chapter are available from the Medizinische Hochschule Hannover collection. The following videos are included with this chapter and may be viewed at https://expertconsult.inkling.com :
- 44-1.
Distal radius fracture: bridging external fixation.
- 44-2.
Distal radius fractures: nonbridging and transarticular external fixation.
- 44-3.
Extensor indicis transfer for rupture of the extensor pollicis longus tendon.
- 44-4.
Corrective osteotomy for malunion of the distal radius.
- 44-5.
Fractures of the styloid process: indications for surgery, techniques.
Although Colles first described the distal radius fracture in 1814, considerable controversy remains regarding the classification, appropriate treatment, and anticipated outcome of these injuries. Colles initially stated that the wrist would eventually gain “perfect freedom in all of its motions and be completely exempt from pain” after this fracture. This perpetuated the concept of distal radius fractures as a homogeneous group of injuries that could be treated nonoperatively with an expected good functional outcome.
It is now appreciated that well over half of these fractures involve either the distal radioulnar or the radiocarpal joint and that conventional reduction by traction or manipulation may not restore distal articular anatomy. Furthermore, many of these fractures, although initially reducible by manipulation, may be inherently unstable and may collapse with simple cast immobilization. More recent reports have confirmed a direct correlation between late functional results and residual deformity, especially in younger, more active patients. Emphasis has shifted toward efforts to restore articular congruency and the bony anatomy of the distal radius using operative means when appropriate. The advent of anteriorly applied locking plates has revolutionized the treatment of these injuries, allowing for stable fixation with an earlier rehabilitation and recovery of motion and function for many fracture types. Despite the popularity of volar plate fixation, other means of fixation such as fragment-specific fixation and dorsal bridge plating have gained popularity for specific types of fractures over the past decade and are important parts of wrist surgeons’ armamentarium.
Functional Anatomy
The distal end of the radius forms the anatomic foundation of the wrist joint. The flare of the radial metaphysis begins approximately 2 to 3 cm proximal to the radiocarpal joint. The articular surface of the distal radius is divided into two articular facets for the scaphoid and lunate by a longitudinal sagittal ridge ( Fig. 44-1 ). The ulnar surface of the distal radius has a separate articular facet, the sigmoid notch, for the seat of the ulna. It is here that forearm rotation takes place as the radius and carpus rotate around the ulna. The triangular fibrocartilage spans from the distal edge of the radius to the base of the ulnar styloid process, stabilizing the distal radioulnar joint (DRUJ) and supporting the ulnar carpus.
The normal distal radius articular surface inclines radially between 22 and 23 degrees in the frontal plane ( Fig. 44-2 ). The joint surface slopes palmward between 4 and 22 degrees, with an average palmar inclination of 10 to 12 degrees. This is best appreciated on a true lateral radiograph. Radial length refers to the distance between the tip of the radial styloid process and the distal articular surface of the ulnar head. The average radial length is 11 to 12 mm. Ulnar variance is the relative length between the head of the ulna and the articular surface of the distal radius. This measurement must be taken from a neutral rotation posterior-anterior (PA) radiograph because forearm rotation affects the relative length from the distal radius to the ulna. The average ulna and radius end within 1 mm of one another. These anatomic parameters have become well accepted in the radiographic evaluation of distal radius fractures (see Fig. 44-2 ).
Classification
Classification systems serve as a basis for treatment and provide a means of evaluating the outcome of different treatment procedures. Perhaps in no other area of skeletal injury have eponyms enjoyed such longevity as in fractures of the distal radius. Classification of these fractures as Colles, Smith, or Barton fractures continues in clinical practice and in the literature. However, most fractures of the distal radius do not fall into the simple extraarticular patterns described by Colles and Smith. The use of these terms has led to conflicting data with regard to treatment recommendations and expected outcome.
Since the 1960s, a number of classification schemes have been developed in an attempt to describe more accurately the variety and extent of fracture patterns of the distal radius. In 1967, Frykman established a system of classification that identified involvement of the radiocarpal and DRUJs as well as the presence or absence of a fracture of the ulnar styloid. Although this system has been used by many investigators, it fails to identify the extent of intraarticular injury or the degree of displacement or dorsal comminution. Simple low-energy fractures with minimal angulation and shortening are classified together with high-energy fractures that involve multiple displaced fragments. This system, therefore, has little value as a treatment guide or a predictor of outcome.
Jupiter and Fernandez developed a more useful classification based in part on the mechanism of injury. It reflects a better understanding of the various fracture patterns:
- 1.
Bending —metaphysis fails under tensile stress (Colles, Smith)
- 2.
Compression —fracture of the joint surface with impaction of subchondral and metaphyseal bone (die punch)
- 3.
Shearing —fractures of the joint surface (Barton, radial styloid)
- 4.
Avulsion —fractures of ligament attachments (ulna, radial styloid)
- 5.
Combinations of 1 through 4—high-velocity injuries
Melone introduced the concept that fractures of the distal radius often follow a similar pattern with respect to intraarticular fragmentation. He described four basic components of these fractures that are common and identifiable: (1) the radial shaft, (2) the radial styloid (scaphoid facet of the distal radius), (3) the dorsal aspect of the lunate fossa, and (4) the palmar aspect of the lunate fossa. The lunate fossa fragments are pivotal to both radiocarpal and DRUJ function and are termed the medial complex. A large percentage of so-called extraarticular fractures have nondisplaced intraarticular components that occur within these guidelines, the most common of which involves the dorsal aspect of the lunate facet. Using these fragments as a guide, Melone classified intraarticular fractures into five types based on the extent of comminution and separation of the fragments.
The most detailed of the classification systems is the Arbeitsgemeinschaft für Osteosynthesefragen (AO) system ( Fig. 44-3 ). This scheme is organized in order of increasing severity of the osseous and articular lesions. The classification divides distal radius fractures into extraarticular (type A), partial articular (type B), and complete articular (type C). Each type is then subdivided into three groups. Type C, for example, can be divided into C 1 (simple articular and metaphyseal fracture), C 2 (simple articular with complex metaphyseal fracture), and C 3 (complex articular and metaphyseal fractures). These groups, in turn, can be further subdivided into subgroups, reflecting the morphologic complexity, difficulty of treatment, and prognosis. Several studies have shown reliability and consistency in the ability of different assessors to agree on fracture type but to lesser extent on group and subgroup ( Fig. 44-3 ).
Unfortunately, despite multiple attempts at generating comprehensive classification schemes for distal radius fractures, both the intraobserver and interobserver reliability of the systems remains fair to moderate. This is likely because of the bony complexity of the distal radius and the variability of injury. Thus, it often is beneficial to apply the principles of several classification systems when evaluating a particular injury.
Classification of fractures by anatomic type using the number of fracture “parts” was introduced as a more clinically useful scheme by which to describe fractures of the distal radius. This system is used in this chapter. It uses the fracture fragment principles of Melone but expands these to include extraarticular and intraarticular fracture patterns. For the purposes of this classification, a part is defined as a fragment of bone of sufficient size to be functionally significant and capable of being manipulated or internally fixed.
Extraarticular Fractures
Extraarticular fractures are those that do not affect either the radiocarpal or the DRUJ. These are two-part fractures (involving the radial shaft and the articular segment), and they characteristically occur in the distal 3 to 4 cm of the radius. If they are displaced, a certain degree of injury or disruption of the DRUJ must be present unless a fracture of the ulna proximal to the DRUJ also occurs ( Fig. 44-4 ). Two-part extraarticular fractures can be associated with a minimal or a marked degree of dorsal comminution. The degree of initial displacement and comminution determines whether these injuries remain stable after being reduced (see later discussion).
Intraarticular Fractures
Intraarticular injuries include any fracture that extends into the radiocarpal or radioulnar joint and is displaced more than 1 to 2 mm. These fractures are further subdivided into fractures with two, three, four, and five or more parts.
The most common of the two-part intraarticular fractures are the simple transverse bending fractures, which enter the DRUJ but do not involve the radiocarpal articulation. Although these are often referred to as extraarticular fractures, they do disrupt the sigmoid notch of the distal radius and can lead to dysfunction of the DRUJ (pain and limitation of forearm rotation). DRUJ involvement should not be overlooked in fractures of the distal radius. This is often best appreciated on a hypersupinated anterior-posterior (AP) radiograph, which tends to show the DRUJ in direct profile (see Fig. 44-21 ).
Two-part intraarticular fractures that involve the radiocarpal joint include the dorsal and palmar Barton fractures. These are typically associated with radiocarpal subluxation. The radial styloid (chauffeur’s) fracture and the dorsoulnar impacted (die-punch) fracture are also in this category. A critical factor regarding these injuries is that the opposite portion of the radiocarpal joint remains intact and therefore in continuity with the remainder of the radius ( Fig. 44-5 ).
The three-part intraarticular fracture typically involves the lunate and scaphoid facets of the distal radius, which are split by a longitudinal fracture line. These fragments are displaced both from each other and from the proximal radius ( Fig. 44-6 ). The lunate facet is particularly critical, because it articulates not only with the radiocarpal joint but also with the DRUJ. This fracture is analogous to the medial complex fracture described by Melone.
The four-part intraarticular fracture is the same fracture as the three-part fracture with further separation of the lunate facet into dorsal and volar fragments. In general, any displaced intraarticular fracture extending into the lunate facet in the coronal plane (as seen on the lateral radiograph) must also be associated with a fracture extending into the DRUJ ( Fig. 44-7 ). The intraarticular fracture with five or more parts comprises a wide variety of high-energy distal radius fractures. At times the extent of disruption of the joint surface precludes direct manipulation or fixation.
Radiographic Assessment
The basic imaging techniques used in the evaluation of distal radius fractures are plain radiography, computed tomography (CT), and fluoroscopic examination. Most distal radius fractures can be adequately assessed with high-quality radiographic views. These are required to define the “personality” of the fracture, which is determined by the degree of initial displacement and the intrinsic stability of the fragments after reduction. The importance of the initial radiographs in the determination of fracture stability is critical. For example, two radius fractures that are perfectly reduced, where one was initially very comminuted and displaced and the other was only slightly angulated, will behave very differently after reduction.
In addition to standard PA and lateral views, additional radiographs are often essential. Directing the lateral view 20 to 25 degrees from distal to proximal improves visualization of the distal radius articular surface. The partially supinated oblique PA view allows evaluation of the dorsal facet of the lunate fossa (i.e., dorsomedial facet) ( Fig. 44-8 ). The partially pronated oblique PA view best projects the radial styloid ( Fig. 44-9 ). Oblique views frequently reveal intraarticular extension or displacement not appreciated on standard frontal and lateral projections. The DRUJ is frequently not in direct profile on standard PA projections. Transverse metaphyseal fractures of the distal radius often exit at the DRUJ and the only clue to step-off at the joint will be a step-off on the radial side until a hypersupinated radiograph or a true neutral rotation PA projection is obtained with the DRUJ in direct profile, demonstrating the displacement (see Fig. 44-21 ). The importance of good-quality radiographs (out of a splint if necessary) cannot be overemphasized in planning treatment. Inadequate radiographs and subsequent poor fracture characterization have contributed, in part, to the difficulty in comparing results among various treatment methods for these injuries.
Computed tomography can be valuable in accurately defining anatomic disruption, particularly for intraarticular fractures with multiple components. This technique permits a clear definition of the fragments and their displacement. Often, centrally impacted fragments cannot be appreciated on plain radiographs. Sagittal and coronal reformatted views allow clear visualization of these fragments and almost always reveal greater comminution and displacement than can be appreciated on plain radiographs ( Fig. 44-10 ).
Last, a significant amount of information can be obtained by performing a fluoroscopic examination with the patient under regional or general anesthesia. At times, it may be difficult to determine the precise nature of the fracture with routine radiographs. Cast or splint material may further obscure fracture detail. This usually occurs in highly comminuted or displaced fractures. A fluoroscopic examination under traction may permit a greater understanding of the fracture and may indicate a treatment method more specifically tailored to meet the needs of the fracture. It is common for operative decisions, such as those regarding the need for open reduction and inspection of the joint surface, to be made at the time of surgical intervention, when more detailed images can be obtained.
Determination of Stability
Most distal radius fractures can be reduced initially by manipulative closed reduction. This technique uses ligamentotaxis (fracture reduction through intact ligaments) to restore anatomic relationships. The stability of a fracture is best defined as its ability to resist displacement after it has been manipulated into an anatomic position. In addition to the anatomic type, a number of local factors contribute to fracture stability, including the degree of metaphyseal comminution, the quality of the bone, the energy of the injury, and the degree of initial displacement.
Comminution, or fracture fragmentation, tends to increase with both the energy of the injury and the patient’s age. The extent of cortical comminution is of particular importance in predicting the intrinsic stability of fracture reduction. Bone quality reflects the underlying skeletal osteopenia and has a direct relation to the fracture’s tendency to shorten and the ability of the bone to achieve a strong interface with implants. Fractures of the distal radius are more common in postmenopausal women, and the quality of the bone has a direct relation to treatment options. For example, the combination of a dorsal bending mechanism with substantial dorsal comminution creates an environment at high risk for collapse. The difficulty of maintaining reduction with casting or nonrigid internal fixation influences treatment decisions in this group of patients.
The energy imparted to the bone and soft tissues at the time of injury also affects fracture stability. Fractures of the distal radius most often result from a fall on the outstretched hand and involve relatively low energy. These, as previously noted, are found more frequently in postmenopausal women with localized or generalized osteoporosis. In contrast, young adults tend to incur high-energy injuries, which correspondingly present more difficulties in management. Greater degrees of displacement, articular impaction, comminution, and subsequent instability are present with high-energy injuries.
Displacement refers to the extent to which the bone, joint, or both have been disrupted from the normal alignment. The greater the extent of displacement, the more likely it is that soft tissue stripping and instability are also present. The degree of initial fracture displacement is very important and must be considered in evaluating treatment options. In addition, the treating physician must bear in mind the correlation between the extent of displacement and associated swelling or neurovascular compromise.
In an attempt to define more precisely the unstable distal radius fracture, Cooney and coworkers considered those fractures widely displaced with extensive dorsal comminution, a dorsal angulation of 20 degrees or more, or extensive intraarticular involvement to have a significant chance of redisplacement after reduction. Weber extended this concept to include any fracture in which the dorsal comminution is seen to extend volar to the midaxial plane of the radius on a lateral radiograph. LaFontaine and associates suggested five factors that indicate instability of distal radius fractures: (1) initial dorsal angulation greater than 20 degrees, (2) dorsal metaphyseal comminution, (3) radiocarpal intraarticular involvement, (4) associated ulnar fractures, and (5) patient age older than 60 years. Nesbitt and coworkers found age to be the most significant risk factor in predicting secondary displacement and instability. Last, Abbaszadegan and colleagues suggested that instability is present if the initial radiograph reveals more than 4 mm of impaction or axial shortening. It is clear from this discussion that absolute guidelines with respect to fracture stability have yet to be established. Each local factor contributes to stability, and a judgment must be made with respect to the ability to maintain fracture reduction in a splint or cast. Borderline fractures treated nonoperatively must be observed closely with repeat radiographs to evaluate displacement.
Relation of Anatomy to Function
Loading patterns across the wrist are affected by very minor changes in distal radial geometry. Axial loads at the radiocarpal joint are normally distributed primarily onto the radius (82%), with additional loading at the distal ulna through the triangular fibrocartilage complex (18%). At approximately 10 degrees of dorsal tilt of the distal radius, the load bearing across the radiocarpal joint begins to change significantly. For example, at 20 degrees of dorsal tilt, the ulna bears 50% of the load, and the radiocarpal forces become dorsally shifted and concentrated at the scaphoid articular facet. At 45 degrees of dorsal tilt, the ulna bears 67% of the axial load across the wrist. As little as 2.5 mm of radial shortening also significantly shifts force loading to the distal ulna (from 18% to 42% of total load). This additionally disturbs the relationships and the forces at the DRUJ, which can manifest as pain and limitation in forearm rotation (in addition to ulnocarpal impingement). These biomechanical parameters support the need for more aggressive approaches to restore anatomic relationships after fracture of the end of the radius.
Several contemporary prospective studies have focused on the relation between anatomy and function. Howard and coworkers, in a study comparing external fixation and plaster immobilization, found that functional results had a significant relation to the quality of the anatomic restoration and were less influenced by the method of immobilization. These findings were confirmed in additional prospective studies by van der Linden and Ericson, Porter and Stockley, and Jenkins and associates. In each of these studies, function, as reflected in grip strength and endurance, was impaired if the fracture healed with more than 20 degrees of dorsal angulation or less than 10 degrees of radial inclination. Radial shortening was associated in some cases with disruption of the DRUJ. Overall, a number of studies have suggested a direct relation between residual deformity and disability, especially in younger, higher demand patients. *
* References .
Residual intraarticular incongruence also has implications for late functional results and the development of degenerative arthrosis. Although mild articular involvement in low-energy fractures in older postmenopausal women has little impact on the generally favorable outcome found with these patients, this is not necessarily the case in younger, more vigorous persons. Impacted intraarticular fractures have received more attention in recent years because failure to reduce these fractures to within 2 mm of articular congruity, especially in young adults, will probably lead to symptomatic posttraumatic arthritis. †† References .
Articular impaction fractures in younger patients are more often the result of high-energy trauma and can be associated with a spectrum of injuries, including carpal instability, disruption of the DRUJ, and local soft tissue trauma. With greater understanding of the pathomechanics of these fractures has come the recognition that conventional manipulation or reduction by traction may not adequately reduce many of these impacted or rotated articular fractures and may not restore intracarpal ligament dissociations.A number of studies have highlighted the importance of the DRUJ in the overall functional outcome after distal radius fracture. This joint can be affected both by diastasis resulting from direct injury and by residual deformity of the distal radius. Although Darrach’s procedure of distal ulna excision was initially met with a high degree of enthusiasm, a predictable successful outcome has not always been achieved. Distal ulnar instability and weakness have tempered the interest in distal ulna excision, thus placing importance on restoration of the DRUJ anatomy after fracture in more active individuals.
Controversy exists regarding the precise relation between distal radius residual deformity and functional results in the elderly and lower demand population. It is well recognized that adequate and painless wrist function can coexist with radiographic deformity in certain individuals. However, even studies that have observed successful outcomes that did not correlate with anatomic restoration have noted that objective results may be inferior to the subjective results.
Evidence continues to mount over the past decade supporting nonsurgical treatment for even displaced and unstable fractures of the distal radius in the elderly population. In a randomized controlled trial (RCT), Arora and colleagues compared nonoperative treatment versus volar fixed-angle plating in patients older than 65 years and found improved function in the operative group in the early postoperative period and improved grip strength at all time points. However, a higher complication rate and no differences in pain, functional scores, or range of motion were observed at 1 year. Diaz-Garcia and colleagues, in a meta-analysis of 21 high-quality studies comparing cast immobilization with multiple surgical treatment types, found statistical differences in range of motion and functional scores. However, the differences were quantitatively small and deemed likely not clinically relevant. The complication rates were higher in the operative groups with most major complications due to volar fixed-angle devices, largely caused by tendon rupture or adhesions.
Given the fact that most distal radius fractures occur either in young patients with the potential for remodeling or in older patients with generally lower functional demands, it is not surprising that in most large clinical series, the majority of patients do relatively well.
Problems do exist, however, particularly with high-demand patients. Bacorn and Kurtzke evaluated a large number of patients with work-related distal radius fractures and found an average disability of 24% of the involved limb and no disability at all in only 3% of cases.
Treatment
Patient Considerations
Before considering the treatment of the fracture itself, all patients with distal radius fractures should be considered for possible bone density workup and treatment, especially perimenopausal women. High-risk patients include all those older than 65 years of age; middle-aged women; and younger patients with chronic disease processes such as a history of transplantation, chronic renal disease, or immobility for any reason. The incidence of hip fracture within the first year after distal radius fracture in patients older than 60 years old is nearly six times greater than in control participants without fracture and is highest at 17 times the risk within the first month, likely because of a combination of fall risk and bone density. Younger individuals may also be at risk. Rozenthal and colleagues compared bone density in premenopausal women with radius fractures with control participants and found decreased bone density in the patients with fractures. With increasing awareness of vitamin D deficiency and suboptimal bone health, density assessment must be considered when evaluating these individuals. Theoretical concerns exist with starting bisphosphonate treatment soon after a fracture is sustained. However, in a randomized trial, Gong and colleagues found no disadvantage to starting bisphosphonates at 2 weeks after fracture compared with at 3 months.
The initial selection of treatment options after fracture of the distal radius must be made in the context of the patient’s needs and functional requirements. Similar fractures in the dominant wrist of a 20-year-old athlete and in the nondominant wrist of a 72-year-old nursing home patient do not necessarily dictate similar treatment. Patient evaluation should take into consideration a combination of age, occupation, handedness, and lifestyle requirements. It must not be based solely on the chronologic age of the patient. The patient’s psychological outlook and associated medical conditions should also be considered.
The workup of a patient with a distal radius fracture should consist of a careful medical history, general physical examination, and routine laboratory testing. The coexistence of life-threatening injuries or long-standing systemic illnesses may represent a relative contraindication for more invasive management. A history of substance abuse or recurrent poor compliance also represents a relative contraindication to complicated treatment options. Appropriate treatment requires matching a patient’s needs and the character of the fracture with the best treatment alternative.
An example of a patient with a high loading expectation is a laborer or someone frequently involved in recreational sporting activities. The loads borne on the distal radius and ulna in normal functional activities have never been accurately defined. Brand and associates calculated the potential force generated by the forearm musculature to be approximately 500 kg. Young, active patients would be expected to have high loading of the distal radius with vigorous activities over many years. Anticipated functional loading should influence treatment far more than the patient’s age. Efforts should be concentrated on restoration of distal radius geometry and articular congruency in these more active individuals.
Options
The methods for treatment of fractures of the distal radius most simply include above-elbow and below-elbow cast immobilization, percutaneous pins and cast immobilization, external fixation with or without percutaneous pins, and limited or formal open reduction. The options for internal fixation, however, have evolved in recent years, with dorsal plating being largely replaced by volar fixed-angle fixation for most fractures. Arthroscopically assisted reduction, fragment-specific fixation, and dorsal bridge plating have roles in certain fracture types as well. In dealing with complex fractures, a combination of these methods may be required.
It is important to note that over the past 10 to 20 years, there has been a major shift in the way distal radius fractures are treated worldwide toward operative management and specifically internal fixation. Wilcke and colleagues, in a large Swedish database study of more than 42,000 patients, found that between just 2004 and 2010, the number of surgical procedures for distal radius fractures increased 40% despite a decreased incidence of injury. Over the same period, adult patients treated with plate fixation increased from 16% to 70%, with an almost equal drop in the use of external fixation. Similarly, Mattila and colleagues, in a Finnish database study of more than 14,000 distal radius operations between 1998 and 2008, found that the incidence of plating nearly doubled over the study period. This highlights the current shift away from external fixation toward internal plate fixation for these injuries.
Treatment of Extraarticular Fractures
Stable Fractures
Closed reduction with cast immobilization remains an acceptable method of treatment for approximately 75% to 80% of distal radius fractures that are considered inherently stable. Stable fractures are generally those that are undisplaced or only minimally displaced and impacted at the time of presentation. As previously stated, significant initial displacement and dorsal comminution are signs of fracture instability.
With a stable extraarticular fracture, a simple below-elbow or “sugar-tong” splint molded over the fracture site suffices initially in most patients. The splint remains in place for the first week after fracture reduction and is then replaced by a cast. Care is taken to end the splint proximal to the palmar metacarpophalangeal joint flexor crease. Digital motion is stressed throughout the healing phase. Follow-up radiographs at 1 and 2 weeks are necessary to monitor any displacement within the cast. Because of diminished soft tissue swelling and atrophy from disuse, several new, well-molded casts are required during the typical 5- to 6-week period of immobilization.
Despite the widespread acceptance of cast immobilization, questions remain as to the optimal position for immobilization and the need to extend support above the elbow. Several studies have addressed these issues in a prospective manner, looking at different positions of the hand and wrist, functional bracing with the forearm in supination versus short arm splints, and long arm versus short arm casts. Neither position of immobilization nor extension above the elbow appeared to influence the anatomic outcome to any noteworthy degree in these studies. This suggests that maintenance of fracture alignment depends mostly on the inherent characteristics of a given fracture (e.g., initial displacement, comminution, bone quality). We therefore tend to favor short arm cast immobilization for stable distal radius fractures.
Loss of reduction of fractures during cast or splint immobilization is common, and remanipulation has been reported. Unfortunately, two retrospective studies found displacement to recur in 46% and 67% of cases after remanipulation. A greater likelihood of retaining the reduction was noted in younger patients and in fractures remanipulated between 7 and 15 days after the initial reduction, but the failure rate was still quite substantial. Thus, loss of reduction in a cast is a sign of fracture instability, and consideration should be given to more aggressive treatment if warranted by the patient’s functional requirements.
Unstable Fractures
A number of treatment options exist to offset the loss of reduction in an unstable extraarticular distal radius fracture in a patient in whom the maintenance of anatomic position is deemed important. These include percutaneous pinning of the distal fragment, external skeletal fixation devices, and open reduction and internal fixation (ORIF). The development of anteriorly applied locking plates has revolutionized the treatment of these injuries and is currently the most commonly used surgical method. Intramedullary nailing, however, deserves mention as a minimally invasive treatment method for which adequate radiographic and functional results have been reported in select cases.
Percutaneous Pins
Extraarticular fractures with displacement and extensive comminution have been historically amenable to percutaneous pinning of the fracture fragments and application of a cast. Anatomic position was maintained in 28 of 30 patients reported by Clancey and in the majority of those reported by Benoist and Freeland with minimal complications. This technique, however, has less optimal results in high-energy, complex fractures. Benoist and Clancey recommended supplemental bone grafting in this subset of injuries. Fractures associated with soft tissue problems that would preclude a circular cast are also a relative contraindication to this treatment method. Percutaneous pinning can effectively be combined with external fixation in these cases, as discussed later.
The technique of percutaneous pinning involves an image intensifier. Regional anesthesia is preferred. If the fracture is treated within 5 to 7 days after injury, manipulative reduction should be all that is required to restore radial length and a normal volar tilt. The reduction is accomplished with traction, ulnar deviation, and dorsal pressure applied to the distal fragment and counterpressure on the volar cortex of the radial shaft ( Fig. 44-11 ). Reduction is held while two crossed 0.062-in Kirchner wires (K-wires) are placed to secure the fracture position. These are introduced percutaneously with a power wire driver. Pins smaller than 0.062-in in diameter provide minimal resistance to torsion and bending forces. The accuracy of the reduction and the placement of the wires are confirmed with fluoroscopic or plain radiographic imaging.
Both K-wires are cut beneath the skin, and a circular plaster or fiberglass cast is applied (with the tourniquet deflated). Again, digital motion is important and should be begun immediately. Follow-up radiographs are taken at 5 to 7 days to ensure maintenance of reduction and to apply a new, well-fitting cast. At approximately 5 to 6 weeks, the pins are removed, and at approximately 6 weeks, the cast is changed to a wrist splint, which allows wrist range of motion exercises with interval splinting for comfort and support.
Although most fractures do not redisplace with this method, poor osteoporotic bone or excessive dorsal comminution may lead to settling or pin migration with loss of reduction. Even while the wrist is casted, compressive loads cross the wrist with daily activities. Therefore, fractures treated with this method must be monitored closely. If signs of instability exist at the time of pin fixation or if bone quality is very poor (and maintenance of alignment is deemed important for a given patient), consideration should be given to more stable surgical options. Although percutaneous pinning is still very useful as definitive fixation in pediatric patients with good bone quality, in most cases, palmar locking plates have replaced pins and casting for the treatment of these fractures (see following section). It should be noted, however, that there may still be a role for percutaneous pinning alone in lower demand elderly patients because it can achieve improved radiographic alignment compared with cast treatment while being less invasive than plating.
External Skeletal Fixation
External skeletal fixation, although very commonly used in the past in the treatment of unstable extraarticular distal radius fractures, is much less popular today. For the most part, it has been replaced by newer anterior locking plate technology. Plating systems obviate the need for distraction, immobilization, and pin tract soft tissue problems associated with the use of an external frame. However, external fixation is clearly an effective method of treatment, and a number of studies have reported favorable results with its use. Several prospective, randomized studies comparing external fixation with cast immobilization for unstable distal radius fractures documented external fixation to be superior in maintaining fracture position and with respect to overall hand function. In fact, external fixation has been shown to yield better long-term outcomes than previously available open reduction methods (before anterior locked plating). Interest in the dynamic external fixation concept that allows for wrist motion while traction is maintained has been tempered by the complexity of the operative protocol and studies that showed greater loss of reduction, more complications, and no benefit in wrist motion with this procedure compared with those in static external fixation.
When applied in conjunction with percutaneous pins or bone grafting through a limited exposure, the external fixation device can be removed as early as 4 to 5 weeks after application. Protected wrist motion is begun at approximately 6 weeks, with interval splinting for comfort and support. If applied without adjuvant treatment, the device is best left in place for 6 to 8 weeks, until union has occurred.
The technique of applying external fixation depends on strict attention to detail (Video 44-1). The placement of the fixator pins can be accomplished before fracture reduction, but this alters the skin tension on the pins after the fracture is reduced. This problem can be avoided by obtaining an adequate reduction before placement of the external fixator pins. Supplemental K-wire fixation, as outlined previously, is a simple means of maintaining reduction before the fixator is applied. In this way, the external fixator functions as a stable neutralization device and is not the sole means of maintaining fracture position. This technique requires less distraction across the wrist by the fixator (which is deleterious both to digital motion and perhaps ultimately to wrist motion) to maintain reduction. The addition of supplemental K-wires also significantly improves fracture stability, thereby facilitating union.
The locations of the external fixator pins can be marked over the index metacarpal and distal forearm before application ( Fig. 44-12 ). Forearm pins are best placed just proximal to the first dorsal compartment outcropper muscles along the dorsoradial forearm between the extensor carpi radialis longus and brevis tendons. The metacarpal pins should be placed approximately 45 degrees off the horizontal plane of the palm to permit retroposition of the thumb. We advocate small incisions, which afford protection to the radial sensory nerve branches and allow central pin location with the bone. Even in the hard cortical bone of young adults, predrilling is typically unnecessary when using the 2.5-mm threaded half (Schanz) pins. By placement of pins at a slight angle, a greater degree of thread can be maintained within the narrow diaphysis of the second metacarpal.
After placement of the pins, an external frame is constructed and secured with slight radiocarpal distraction and the wrist in near-neutral position. Care must be taken to release the skin tension about the Schanz pins at completion to avoid local skin necrosis and subsequent pin tract problems. Although superficial pin tract infections are common, the majority respond to local antibiotics and local wound care, and osteomyelitis is rare. After fixator placement, digital motion must begin immediately, including the thumb. Patients often feel more secure if the wrist is supported in a palmar splint during fixator wear. This can be applied by an occupational therapist who monitors digital motion, edema, and pin tract care.
For unstable extraarticular injuries with large distal fragments, some investigators report placing the distal external fixator pins into the distal fragment without bridging the wrist (Video 44-2). In this way, earlier motion and return of function can be restored. However, when compared with treatment options that allow for early mobilization of the wrist, no measurable ultimate loss of motion or function can be identified with the use of static external fixation. In the wrist, early motion simply allows for a more rapid return of function after fracture.
Open Reduction
Open reduction and internal fixation is currently the most common treatment method used for unstable extraarticular fractures. This is because of the popularity of the newer anterior locking plate systems. * This technology uses stable fixation applied to the radial shaft and distal screws or bolts placed beneath the articular surface, which lock into the plate. Reduction is maintained by plate application to the tension side of the bone without compromise of fixation. With these fixed-angle constructs, there is no need to expose or fill the dorsal defect created by the initial fracture comminution and displacement ( Fig. 44-13 ). Anterior plating allows for a low-profile implant that does not have the tendon problems associated with larger dorsally placed implants. Furthermore, reduction is facilitated with exposure of the anterior cortex of the radius. This cortex is thicker and more easily allows for proper reduction with reconstitution of length, tilt, and rotation of the distal fragment relative to the radial shaft.
* References .
The utilitarian approach to the distal radius anteriorly is through the floor of the flexor carpi radialis (FCR) tendon ( Fig. 44-14 ). The tendon sheath is opened, and the tendon is retracted ulnarly. The floor of the tendon sheath is then opened with a knife, and the carpal canal contents (flexor tendons and the median nerve) are gently swept from radial to ulnar to expose the pronator quadratus, which blankets the distal radius anteriorly. Several small recurrent radial artery vessels may be seen as the tendons and median nerve are swept ulnarly. These are coagulated. Care is taken to keep all dissection at and radial to the plane of the FCR. This protects the palmar cutaneous branch of the medial nerve, which travels between the FCR and the palmaris longus on its way to innervate the radial palm. We generally recommend a concomitant release of the transverse carpal ligament if any preoperative median nerve symptoms exist. This can easily be accomplished through a separate palmar incision.
An alternative but much less commonly required approach involves exposure more ulnarly, bringing the flexor tendons, median nerve, radial artery, and FCR laterally. This wider exposure has the advantage of offsetting the potential for persistent retraction on the median nerve during the procedure. It affords a more direct view of the anterior aspect of the lunate facet. With this extended approach, the transverse carpal ligament is routinely released, allowing a wider zone of mobility for the soft tissue structures. This approach is ideal for isolated fractures of the volar lunate facet because it provides easier visualization and a more direct line for placing internal fixation from the ulnar side ( Fig. 44-15 ).
Whichever exposure is chosen, next the pronator quadratus is incised radially. The pronator muscle is elevated, and subperiosteal dissection is carried medially and laterally to expose the anterior radius. Distally, care is taken not to incise the important anterior wrist ligaments. From the anterior approach, the distal radius joint surface is thus not visualized. Ulnarly, the pronator muscle is elevated until the anterior aspect of the lunate facet is exposed. Radially, dissection is continued until the tendons of the first dorsal compartment are visualized. Beneath these, the brachioradialis insertion can be subperiosteally released or cut because this is a deforming force on the distal fragment.
The reduction is facilitated by control of the shaft of the radius proximal to the fracture with a claw-type clamp. After the fracture line is identified and cleaned, the distal fragment is translated and reduced. In many cases, no significant comminution of the thick anterior cortex is evident, and reduction is relatively easy to visualize. Cases in which the volar cortex is comminuted ( Fig. 44-16 ) are important to identify on preoperative imaging because in these cases, care must be taken when raising up the pronator quadratus to ensure that the comminuted fragment(s) and any periosteal attachments are not elevated with the pronator. In most cases, even if the volar comminution is broad, there will be at least a small portion that remains intact, often of the intermediate column, to allow for recovery of appropriate length.
Care is taken at this point to ensure reduction of the radius in the medial to lateral plane. Typically, the distal fragment tends to translate radially under the pull of the brachioradialis and the shaft ulnarly because of the interosseous ligament and forearm muscles. After the reduction is accomplished, it can be maintained with a provisional K-wire placed through the radial styloid if required.
The chosen anterior locking plate is then positioned. Most are precontoured for the anterior flare of the distal radius; however, there is variability between how distal plates extend along the anterior rim of the radius. When possible, it is important to have the volar plate extend no farther than the watershed line of the radius ( Fig. 44-17 ). Some very distal fractures may necessitate more distal plate placement, but efforts should be made to keep the plate proximal to the volar rim to avoid flexor tendon irritation and rupture, most commonly of the flexor pollicis longus. Flexor tendon complications have a higher incidence when plates cross the watershed line or protrude volarly ( Fig. 44-18 ). This principle will be covered in further detail later in the chapter. Most volar plates allow for placement of a screw through an oval hole in the radial shaft proximal to the fracture. In this way, the plate position can be adjusted based on intraoperative fluoroscopy. Plate position is verified in both the AP and lateral planes before the distal screws are placed. Use of intraoperative imaging is imperative. Most commonly, the plate is first fixed to the radial shaft. Placement of the distal screws is done while most typically anteriorly and ulnarly translating the distal fragment onto the plate (with translation of the shaft dorsally) to reconstitute volar tilt and coronal balance. Care must be taken when using screws distally to not place them past the dorsal cortex. If the dorsal cortex is used to measure the screw length, several millimeters should be subtracted so as not to have the sharp screw tips compromise the extensor tendons, which are tightly opposed to the dorsal bone. Evidence suggests that dorsal penetration of distal locking screws is hardest to recognize on fluoroscopy centrally and ulnarly. In addition, a dorsal tangential fluoroscopic view obtained nearly in line with the axis of the radius with the wrist flexed has been shown to be highly sensitive in detecting screw penetration into the third and fourth compartments, serving as a nice addition to standard lateral and 45-degree supinated views. The latter is typically sufficient to detect screw penetration into the second compartment.
