Rockwood Children CH8

8

Fractures of the Distal Radius and Ulna William L. Hennrikus and Donald S. Bae

INTRODUCTION TO FRACTURES OF THE DISTAL RADIUS AND ULNA  243

Physeal Arrest of the Distal Radius  289

CONTROVERSIES RELATED TO FRACTURES OF THE DISTAL RADIUS AND ULNA 296 Acceptable Deformity  296 Greenstick Fractures  296 Immobilization  297 Immediate Pinning of Displaced Distal Radius Fractures  297 Open Fractures  297

ASSESSMENT OF FRACTURES OF THE DISTAL RADIUS AND ULNA  244

Mechanisms of Injury of Fractures of the Distal Radius and Ulna  244 Injuries Associated With Fractures of the Distal Radius and Ulna  246 Signs and Symptoms of Fractures of the Distal Radius and Ulna  248 Imaging and Other Diagnostic Studies Fractures of the Distal Radius and Ulna  249 Classification of Fractures of the Distal Radius and Ulna  249

CONCLUSIONS  298

PATHOANATOMY AND APPLIED ANATOMY RELATING TO FRACTURES OF THE DISTAL RADIUS AND ULNA  253

INTRODUCTION TO FRACTURES OF THE DISTAL RADIUS AND ULNA

TREATMENT OPTIONS FOR FRACTURES OF THE DISTAL RADIUS AND ULNA  255 Nonoperative Treatment of Fractures of the Distal Radius and Ulna  255 Operative Treatment of Fractures of the Distal Radius and Ulna  267

Forearm fractures are the most common long-bone fractures in children, occurring with an annual incidence of approximately 1.5/100 children per year 33 and comprising up to 40% of all pediatric fractures. 13,30,33,107,122 Among all forearm fractures, the distal radius and ulna are most commonly affected. 30,122,214 Peak incidences of distal radius and ulna fractures occur during the preadolescent growth spurt. 13,30,122,214 The nondominant arm in males is most commonly affected. Several recent studies suggest that the frequency of pediatric distal radius fractures is rising, likely due to epidemiologic trends toward diminished bone density, increased body mass indices, higher-risk activities, and younger age at the time of initial sports participation. 82,83,116,181 In children younger than 15 years of age, the frequency with which these fractures occur demonstrates considerable seasonal variation. 202 In a prior longitudinal study of 5,013 children over 1 year in Wales, the incidence of wrist and forearm fractures was roughly half (5.9/1,000 per year) in the three winter months compared with the rest of the year (10.7/1,000 per year). In addition, the non-winter fractures were more severe in terms of requiring reduction and hospitalization.

AUTHORS’ PREFERRED METHOD OF TREATMENT FOR FRACTURES OF THE DISTAL RADIUS AND ULNA   282 Torus Fractures  282 Incomplete Greenstick Fractures  282 Bicortical Complete Radial Metaphyseal Injuries  284 Physeal Injuries  285 MANAGEMENT OF EXPECTED ADVERSE OUTCOMES AND UNEXPECTED COMPLICATIONS IN FRACTURES OF THE DISTAL

RADIUS AND ULNA  287 Loss of Reduction  287

Malunion  287 Nonunion  289 Cross-Union  289 Refracture  289

243

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SECTION TWO • Upper Extremity

Because of the greater forces borne and imparted to the radius, as well as the increased porosity of the distal radial metaphysis, distal radial fractures are far more common than distal ulna fractures and so, isolated distal radius fractures do occur regularly. However, fractures of the distal ulna most often occur in association with fractures of the distal radius. 122,158 The metaphysis of the distal radius is the most common site of fore- arm fracture in children and adolescents. 13,116,122 The pediatric Galeazzi injury usually involves a distal radial metaphyseal frac- ture and a distal ulnar physeal fracture that result in a displaced distal radioulnar joint (DRUJ). Galeazzi fracture–dislocations are relatively rare injuries in children with a cited occurrence of 3% of pediatric distal radial fractures. 200 Given the frequency with which these injuries occur, the evaluation and management of distal radius and ulna fractures in children remain a fundamental element of pediatric orthope- dics. Despite established treatment principles, however, care of these injuries remains challenging due to the spectrum of injury patterns, issues of skeletal growth and remodeling, diversity of nonoperative and surgical techniques, evolving patient/family expectations, and increasing emphasis on cost-effective care.

forearm (Fig. 8-1). Conversely, axial loading on the flexed wrist will produce a volarly displaced fracture with apex dorsal angu- lation (Fig. 8-2). Occasionally, a direct blow sustained to the distal forearm may result in fracture and displacement. In addi- tion to the angular deformity caused by axial and bending loads applied to the distal forearm, rotational displacement may also occur, based on the position of the forearm and torsional forces sustained at the time of injury. Fracture type and degree of displacement are also dependent on the height and velocity of the fall or injury mechanism. 214 Indeed, the spectrum of injury may range from nondisplaced torus (or “buckle”) injuries (common in younger children with a minimal fall) or dorsally displaced fractures with apex volar angulation (more common in older children with higher-velocity injuries) (see Fig. 8-1). Displacement may be severe enough to cause foreshortening and bayonet apposition. Adult type inju- ries with intra-articular extension do occur. Rarely, a mechanism such as a fall from a height can cause a distal radial fracture asso- ciated with a more proximal fracture of the forearm or elbow (Fig. 8-3). 12,173 These “floating elbow” situations connote higher- energy trauma and as a result are associated with risks of neuro- vascular compromise and compartment syndrome. 12,173 Fractures of the distal forearm in children typically occur when the radius and/or ulna are more susceptible to fracture sec- ondary to biomechanical changes during skeletal development. Work based on load-to-strength ratio and other measures of bone quality has identified specific times during skeletal development where the biologic properties of the distal upper extremity pro- duce relatively weaker bone, making a child more susceptible to fracture. 65,109,118,147 In these studies, prepubescent boys and girls were found to have lower estimates of bone strength com- pared to same-sex postpubertal peers. From these studies, it can be concluded that children are uniquely susceptible for fracture when longitudinal growth outpaces mineral accrual during rapid

ASSESSMENT OF FRACTURES OF THE DISTAL RADIUS AND ULNA

MECHANISMS OF INJURY OF FRACTURES OF THE DISTAL RADIUS AND ULNA Distal Radius and Ulna Fractures

The mechanism of injury is generally a fall on an outstretched hand. Typically, the extended position of the wrist at the time of loading leads to tensile failure on the volar side of the distal

B

Figure 8-1.  A: Tension failure greenstick fracture. The dorsal cortex is plastically deformed ( white arrow ), and the volar cortex is complete and separated ( black arrows ). B: Dorsal bayonet.

A

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CHAPTER 8 • Fractures of the Distal Radius and Ulna

been shown to decrease the injury rate in snowboarders, espe- cially beginners and persons with rental equipment. 175 As cited above, there is seasonal variation, with an increase in both incidence and severity of fractures in summer. 203 Children who are overweight, have poor postural balance, ligamentous laxity, or less bone mineralization are at increased risk for distal radial fractures. 83,117,123,167,182,214 Although bone quality measures predict that boys had lower risk of fracture than girls at every stage except during early puberty, 147 these fractures have been reported to be three times more common in boys. This may be due to relative risk-taking behaviors or participation in higher risk of injury activities. However, the increased participation in athletics by girls at a young age may change this ratio. Radial Physeal Stress Fractures Repetitive axial loading of the wrist may lead to physeal stress injuries, almost always involving the radius (Fig. 8-4). These physeal stress injuries are most commonly seen in competi- tive gymnasts. 29,47,52,193,194 Factors that predispose to this injury include excessive training, poor techniques, and attempts to advance too quickly in competitive level. Stress injuries have been also observed in other sports including wresting, break dancing, and cheerleading. 76 Galeazzi Fracture Axial loading of the wrist in combination with extremes of forearm rotation (Fig. 8-5) may result in distal radius fractures with associated disruption of the DRUJ, the so-called “pediatric Galeazzi fracture.” 26,40,72,122,127,137,201 In adults, the mechanism of injury usually is an axially loading fall with hyperpronation. This results in a distal radial fracture with DRUJ ligament dis- ruption and dorsal dislocation of the ulna. However, in chil- dren, both supination (apex volar) and pronation (apex dorsal) deforming forces have been described. 126,200 The mechanism of injury is most obvious when the radial fracture is incomplete. With an apex volar (supination) radial fracture, the distal ulna is displaced volarly; whereas with an apex dorsal (pronation) radial fracture, the distal ulna is displaced dorsally. This is evi- dent both on clinical and radiographic examinations. In addi- tion, the radius is foreshortened in a complete fracture, causing more radial deviation of the hand and wrist. In children, this injury may involve either disruption of the DRUJ ligaments or, more commonly, a distal ulnar physeal fracture (Fig. 8-6). 1,172 B Figure 8-2.  Reverse bayonet. A: Typical volar bayonet fracture. Often the distal end of the proximal fragment is buttonholed through the extensor ten- dons ( arrows ). (Reprinted from Wilkins KE, ed. Operative Management of Upper Extremity Fractures in Children. Rosemont, IL: American Academy of Orthopaedic Surgeons, 1994:27, with permission.) B: Intact volar periosteum and disrupted dorsal periosteum ( arrows ). The extensor tendons are displaced to either side of the proximal fragment.

A

growth. 13 As 90% of the radius growth is from the distal physis and accounts for 70% of the loading across the wrist, the radius is more prone to fracture than the ulna during rapid growth. 202 Fractures occur at the biomechanically weakest anatomic loca- tion of bone, which also varies over time. As the metaphyseal cortex of the radius is relatively thin and porous, fractures of the metaphysis are most common, followed by physeal. 140,191 Usually, fractures occur during sports-related activities. Indeed, the trend toward increased sports participation in chil- dren has led to a substantial increase in the incidence of distal radius and/or ulna fractures. 102,213 Certain sports, such as skiing/ snowboarding, basketball, soccer, football, rollerblading/skating, and hockey have been associated with an increased risk of distal radial fracture, though a fall or injury of sufficient severity may occur in any recreational activity. 190 Protective wrist guards have

Figure 8-3.  A 10-year-old girl with an innocuous-appearing distal radial fracture associated with an ipsilateral angulated radial neck frac- ture ( arrows .)

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SECTION TWO • Upper Extremity

A

B Figure 8-4.  Radiographic images of the gymnast’s wrist. A: AP radiograph of the left wrist in a 12-year-old female demonstrates physeal widening, cystic changes, and metaphyseal sclerosis. B: AP radiograph of the same wrist after 3 months of rest from gymnastics, demonstrating incomplete resolution of the physeal changes.

ipsilateral extremity fractures. 184 Associated fractures of the hand and elbow regions need to be assessed because their pres- ence implies more severe trauma. For example, the incidence of a compartment syndrome is higher with a “floating elbow” combination of radial, ulnar, and elbow fractures. 173 With marked radial or ulnar fracture displacement, neuro- vascular compromise can occur. 15,44,205 Median neuropathy may be seen in severely displaced distal radius fractures, due to direct

INJURIES ASSOCIATED WITH FRACTURES OF THE DISTAL RADIUS AND ULNA

The risk of associated injuries is significantly less in the skel- etally immature as compared to skeletally mature patients. 58 The entire ipsilateral extremity should be carefully examined for fractures of the carpus, forearm, or elbow. 12,32,91,120,173,184,195 Indeed, 3% to 13% of distal radial fractures have associated

A

B

Figure 8-5.  Supination-type Galeazzi fracture. A: View of the entire forearm of an 11-year-old boy with a Galeazzi fracture–dislocation. B: Close-up of the distal forearm shows that there has been disruption of the distal radioulnar joint ( arrows ). The distal radial fragment is dorsally displaced (apex volar), making this a supination type of mechanism. Note that the distal ulna is volar to the distal radius.

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CHAPTER 8 • Fractures of the Distal Radius and Ulna

C

D Figure 8-5.  ( Continued ) C, D: The fracture was reduced by pronating the distal fragment. Because the distal radius was partially intact by its greenstick nature, the length was easily maintained, reestablishing the congruity of the distal radioulnar joint. The patient was immobilized in supination for 6 weeks, after which full forearm rotation and function returned.

nerve contusion sustained at the time of fracture displacement, persistent pressure or traction from an unreduced fracture, or an acute compartment syndrome (Fig. 8-7). 205 Ulnar neuropathy has been described with similar mechanisms, as well as entrap- ment or incarceration of the ulnar nerve within the fracture site. Wrist ligamentous and articular cartilage injuries have been described in association with distal radial and ulna fractures in adults and less commonly in children. 12,55 Concomitant scaphoid fractures have occurred (Fig. 8-8). 32,41,196 Associated wrist injuries need to be treated both in the acute setting and in the patient with persistent pain after fracture healing. More

than 50% of distal radial physeal fractures have an associated ulnar fracture. This usually is an ulnar styloid fracture, but can be a distal ulnar plastic deformation, greenstick, or complete fracture. 33,107,123,191 Some patients with distal radial and ulna fractures are multitrauma victims. Care of the distal forearm fracture in these situations must be provided within the context of concomitant systemic injuries. Isolated ulnar physeal fractures are rare injuries. 1,185 Most ulnar physeal fractures occur in association with radial metaphyseal or physeal fractures. Physeal separations are classified by the stan- dard Salter–Harris criteria. The rare pediatric Galeazzi injury

Physis

Metaphyseal fracture fragment

Epiphysis

1st metacarpal

Median nerve

Transverse carpal ligament

Hematoma

Figure 8-7.  Volar forearm anatomy outlining the potential compression of the median nerve between the metaphysis of the radius and dorsally displaced physeal fracture. The taut volar transverse carpal ligament and fracture hematoma also are contributing factors. (Redrawn with permission from Waters PM, Kolettis GJ, Schwend R. Acute median neuropathy following physeal fractures of the distal radius. J Pediatr Orthop. 1994;14(2):173–177.)

Figure 8-6.  Galeazzi fracture–dislocation variant. Interposed perios- teum can block reduction of the distal ulnar physis ( arrow ). This desta- bilizes the distal radial metaphyseal fracture. (Reprinted with permission from Lanfried MJ, Stenclik M, Susi JG. Variant of Galeazzi fracture– dislocation in children. J Pediatr Orthop. 1991;11(3):333–335.)

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SECTION TWO • Upper Extremity

A

by testing the abductor pollicis brevis (intrinsic) and flexor pol- licis longus (extrinsic) muscles. Ulnar nerve motor evaluation includes testing the first dorsal interosseous (intrinsic), abductor digiti quinti (intrinsic), and flexor digitorum profundus to the small finger (extrinsic) muscles. Radial nerve evaluation involves testing the common digital extensors for metacarpophalangeal joint extension as well as thumb extensor pollicis longus. Sen- sibility to light touch and two-point discrimination should be tested. Normal two-point discrimination is less than 5 mm but may not be reliably tested in children younger than 5 to 7 years of age. Pinprick sensibility testing will only hurt and scare the already anxious child and should be avoided. Radial Physeal Stress Fracture In contrast to the child with an acute, traumatic distal radius fracture, patients with distal radial physeal stress injuries typi- cally report recurring, activity-related wrist pain. Characteristi- cally, this pain is described as diffuse “aching” and “soreness” in the region of the distal radial metaphysis and physis. Pain may be reproduced in the extremes of wrist extension and flexion, and usually there is local tenderness over the dorsal, distal radial physis. Resistive strength testing of the wrist extensors will also reproduce the pain. There may be fusiform swelling about the wrist if there is reactive bone formation. The differential diag- nosis includes physeal stress injury, ganglion, inflammatory arthritis, ligamentous or TFCC injury, tendinosis or musculoten- dinous strain, carpal fracture, and osteonecrosis of the scaphoid (Preiser disease) or lunate (Kienbock disease). Diagnosis is made radiographically in the context of the clinical presentation. Radiographs are also usually diagnostic in cases of suspected distal radial physeal stress injuries. Physeal widening, cystic and sclerotic changes in the metaphyseal aspect of the distal radial physis, beaking of the distal radial epiphysis, and reac- tive bone formation are highly suggestive of chronic physeal stress fracture. In advanced cases, premature physeal closure or physeal bar formation may be seen, indicating long-stand- ing stress. 29,47,52,176,194,215 In these situations, continued ulnar growth leads to an ulnar positive variance with resulting pain B Figure 8-9.  Dorsal bayonet deformity. A: Typical distal metaphyseal fracture with dorsal bayonet showing a dorsal angulation of the distal forearm. B: Usually, the periosteum is intact on the dorsal side and disrupted on the volar side.

usually involves an ulnar physeal fracture rather than a soft tissue disruption of the DRUJ. Another ulnar physeal fracture is an avul- sion fracture off the distal aspect of the ulnar styloid. 1 Although an ulnar styloid injury is an epiphyseal avulsion, it can be asso- ciated with soft tissue injuries of the triangular fibrocartilage complex (TFCC) and ulnocarpal joint, though does not typically cause growth-related complications. Figure 8-8.  Coronal computed tomography (CT) image of an adoles- cent with ipsilateral distal radius and scaphoid fractures. (Courtesy of Children’s Orthopaedic Surgery Foundation.) Children with distal radial and/or ulna fractures present with pain, swelling, and deformity of the distal forearm (Fig. 8-9). The clinical signs depend on the degree of fracture displace- ment. With a nondisplaced torus fracture in a young child, med- ical attention may not be sought until several days after injury; the intact periosteum and biomechanical stability are protective in these injuries, resulting in minimal pain and guarding. Simi- larly, many of the physeal injuries are nondisplaced and present only with pain and tenderness at the physis. 144,156 With displaced fractures, the typical dorsal displacement and apex volar angu- lation create an extension deformity that is usually clinically apparent. Careful inspection of the forearm is critical to evaluate for possible skin lacerations, wounds, and open fractures. With greater displacement, physical examination is often lim- ited by the patient’s pain and anxiety, but it is imperative to obtain an accurate examination of the motor and sensory components of the radial, median, and ulnar nerves before treatment is initiated. Neurovascular compromise is uncommon but can occur. 205 A prior prospective study indicated an 8% incidence of nerve injury in children with distal radial fractures. 206 Median nerve irritability or dysfunction is most common, caused by direct trauma to the nerve at the time of injury or ongoing ischemic compression from the displaced fracture. Median nerve motor function is evaluated SIGNS AND SYMPTOMS OF FRACTURES OF THE DISTAL RADIUS AND ULNA Traumatic Fractures

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CHAPTER 8 • Fractures of the Distal Radius and Ulna

from ulnocarpal impaction and/or TFCC tear. 12,176,215 Plain radiographs may not reveal early physeal stress fracture. If the diagnosis is suggested clinically, additional studies may be indicated. Technetium bone scanning is sensitive but nonspe- cific. Magnetic resonance imaging (MRI) is usually diagnostic, demonstrating the characteristic “double line” on coronal T1 and gradient echo sequences. 128 Galeazzi Fracture Children with Galeazzi injuries present with pain, limited fore- arm rotation, and limited wrist flexion and extension. Neurovas- cular impairment is rare. The radial deformity usually is clinically evident. Prominence of the ulnar head is seen with DRUJ disrup- tion. Ligamentous disruption is often subtle and may be evident only by local tenderness and instability to testing of the DRUJ. IMAGING AND OTHER DIAGNOSTIC STUDIES FRACTURES OF THE DISTAL RADIUS AND ULNA Plain radiographs are diagnostic of the fracture type and degree of displacement. Standard anteroposterior (AP) and lateral radiographs usually are sufficient. Complete wrist, forearm, and elbow views are recommended in cases of high-energy inju- ries or when there is clinical suspicion for an ipsilateral frac- ture of the hand, wrist, or elbow. More extensive radiographic evaluation (e.g., computed tomography [CT], MRI) is typically reserved for evaluation of suspected or known intra-articular fractures or associated carpal injuries (e.g., scaphoid fractures, hook of hamate fractures, perilunate instability); these situa- tions are most commonly encountered in older adolescents. There has been increasing enthusiasm for the use of ultra- sound in the diagnostic evaluation of distal radius and ulna fractures. 28,60,99,144,156,164 Two independent studies have demon- strated the feasibility and accuracy of bedside ultrasound for diagnosing nondisplaced fractures. 28,164 Ultrasonography is most useful in cases of suspected fractures in the absence of plain radiographic abnormalities, or in very young children in whom the skeletal structures are incompletely ossified. Since ultrasound machines are now commonplace in emergency departments and used by many nonradiology physicians, usage as a screening diagnostic tool is evolving. Radiographic evaluation should be performed not only to confirm the diagnosis but also to quantify the degree of displace- ment, angulation, malrotation, and comminution (Fig. 8-10). Understanding of the normal radiographic parameters is essen- tial in quantifying displacement. In adults, the normal distal radial inclination averages 22 degrees on the AP view and 11 degrees of volar tilt on the lateral projection. 73,139,150,183,222 Radial inclination is a goniometric measurement of the angle between the distal radial articular surface and a line perpendicular to the radial shaft on the AP radiograph. Volar tilt is measured by a line across the distal articular surface and a line perpendicular to the radial shaft on the lateral view. Pediatric values for radial inclination and volar tilt may vary from adult normative values, depending on the degree of skeletal maturity and the ossifica- tion of the epiphysis. Indeed, radial inclination is often less than 22 degrees in younger children, though volar tilt tends to be more consistent regardless of patient age.

As noted above, advanced imaging may be helpful in cases of intra-articular extension to characterize fracture pattern and joint congruity. This may be done by AP and lateral tomograms, CT scans, or MRI. Dynamic motion studies with fluoroscopy can provide important information on fracture stability and the success of various treatment options. Dynamic fluoroscopy requires adequate pain relief and has been used more often in adult patients with distal radial fractures. In Galeazzi fractures, the radial fracture is readily appar- ent on plain radiographs. Careful systematic evaluation of the radiographs will reveal concurrent injuries to the ulna and/or DRUJ (Fig. 8-11). A true lateral radiograph is essential to iden- tify the direction of displacement and thus to determine the method of reduction. Rarely are advanced imaging studies, such as CT or MRI scan, necessary. Figure 8-10.  Angulation of the x-ray beam tangential to the articular surface, providing the optimal lateral view of the distal radius. The wrist is positioned as for the standard lateral radiograph, but the x-ray beam is directed 15 degrees cephalad. (Reprinted by permission from Springer: Johnson PG, Szabo RM. Angle measurements of the distal radius: A cadaver study. Skel Radiol. 1993;22(4):243–246. Copyright © 1993 International Skeletal Society.)

CLASSIFICATION OF FRACTURES OF THE DISTAL RADIUS AND ULNA Distal Radius and Ulna Fractures

Distal Forearm Fractures: GENERAL CLASSIFICATION

Physeal fractures  Distal radius  Distal ulna

Distal metaphyseal (radius or ulna) Torus Greenstick Complete fractures Galeazzi fracture–dislocations Dorsal displaced Volar displaced

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SECTION TWO • Upper Extremity

Figure 8-12.  Dorsally displaced physeal fracture (type A). The dis- tal epiphysis with a small metaphyseal fragment is displaced dorsally ( curved arrow ) in relation to the proximal metaphyseal fragment.

Salter–Harris type I fractures also usually displaced dorsally. Volar displacement of either a Salter–Harris type I or II fracture is less common (Fig. 8-13). Nondisplaced Salter–Harris type I fractures may be indicated only by a displaced pronator fat pad sign (Fig. 8-14), 177,220 ultrasound, 28,99,155 or tenderness over the involved physis. 143,155 A scaphoid fat pad sign may indicate a scaphoid fracture (Fig. 8-15). 94 Salter–Harris type III fractures are rare and may be caused by a compression, shear, or avulsion of the radial origin of the volar radiocarpal ligaments (Fig. 8-16). 9,125 Triplane-equivalent fractures, 160 a combination of Salter–Harris type II and III frac- tures in different planes, have similarly been reported but are rare. CT scans may be necessary to define the fracture pattern and degree of intra-articular displacement in deciding best treatment options.

Figure 8-11.  Lateral radiograph depicting volar subluxation of the dis- tal ulna in relation to the distal radius, a pediatric Galeazzi equivalent. Careful inspection reveals a distal ulnar physeal fracture.

Distal radius and ulna fractures are classified according to frac- ture pattern, type of associated ulnar fracture, and direction of displacement, angulation, and rotation. Most distal radial metaphyseal fractures are displaced dorsally with apex volar angulation. 191 Volar displacement with apex dorsal angulation occurs less commonly with volar flexion mechanisms. Distal radial and ulna fractures are then defined by their ana- tomic relationship to the physis. Physeal fractures are classified by the widely accepted Salter–Harris system (see below). 27,177 Metaphyseal injuries are often different from their adult equiva- lents, due to the thick periosteum surrounding the relatively thin metaphyseal cortex. Metaphyseal fractures are generally clas- sified according to fracture pattern and may be torus fractures, greenstick or incomplete fractures, or complete bicortical inju- ries. Pediatric equivalents of adult Galeazzi fracture–dislocations involve a distal radial fracture and either a soft tissue disruption of the DRUJ or a physeal fracture of the distal ulna. Physeal Injuries The Salter–Harris system is the basis for classification of phy- seal fractures. 176 Most are Salter–Harris type II fractures. 27 In the more common apex volar injuries, dorsal displacement of the distal epiphysis and the dorsal Thurston–Holland metaph- yseal fragment is evident on the lateral view (Fig. 8-12).

Figure 8-13.  Volarly displaced physeal fracture (type B). Distal epiphysis with a large volar metaphyseal fragment is displaced in a volar direction ( curved arrow ). (Reprinted fromWilkins KE, ed. Operative Management of Upper Extremity Fractures in Children . Rosemont, IL: American Academy of Orthopaedic Surgeons; 1994:21, with permission.)

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CHAPTER 8 • Fractures of the Distal Radius and Ulna

Extensor pollicis brevis

NFS

Radial collateral ligament

A

Abductor pollicis longus

Figure 8-15.  Anatomic relationships of the navicular fat stripe (NFS). The NFS, shaded black, is located between the combined tendons of the abductor pollicis longus and extensor pollicis brevis, and the lateral surface of the carpal navicular. (Adapted from Terry DW, Ramen JE. The navicular fat stripe. Ham J Roent Rad Ther Nucl Med . 1975;124:25, with permission.)

B

C

D

Figure 8-14.  A: Subperiosteal hemorrhage from an occult fracture of the distal radius causes an anterior displacement of the normal pro- nator quadratus fat pad ( arrows ). B: A 13-year-old girl with tender- ness over the distal radius after a fall. The only radiographic finding is an anterior displacement of the normal pronator quadratus fat pad ( arrow ). C: The opposite normal side ( arrow indicates normal fat pad ). D: Two weeks later, there is a small area of periosteal new bone forma- tion ( arrow ) anteriorly, substantiating that bony injury has occurred.

Figure 8-16.  AP radiograph of Salter–Harris type III fracture of the distal radius.

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SECTION TWO • Upper Extremity

Metaphyseal Injuries

intact surrounding periosteum. Rarely, they may extend into the physis, putting them at risk for growth impairment. 157–159 Incomplete or greenstick fractures occur with a combination of compressive, tensile, and rotatory forces, resulting in com- plete failure of one cortex and plastic deformation of the other cortex. Most commonly, the combined extension and supina- tion forces lead to tensile failure of the volar cortex and dorsal compression injury. The degree of force determines the amount of plastic deformation, dorsal comminution, and fracture angu- lation and rotation. With greater applied loads, complete fracture occurs with disruption of both the volar and dorsal cortices. Length may be maintained with apposition of the proximal and distal frag- ments. Frequently, the distal fragment lies proximal and dorsal to the proximal fragment in bayonet apposition. Ulna fractures often associated with radial metaphyseal injuries may occur in the metaphysis, physis, or through the ulnar styloid. Similar to radial metaphyseal fractures, the ulnar fracture can be complete or incomplete. These inju- ries are also characterized according to fracture pattern and displacement. Distal radial fractures also can occur in conjunction with more proximal forearm fractures, 19,205 Monteggia fracture–dislocations, 18 supracondylar distal humeral fractures, 172,183 or carpal fractures. 32,41,91,119 The combination of a displaced supra- condylar distal humeral fracture and a displaced distal radial metaphyseal fracture has been called the pediatric floating elbow. This injury combination is unstable and has an increased risk for malunion and neurovascular compromise including compartment syndrome.

Distal Metaphyseal Fractures: CLASSIFICATION

Directional displacement Dorsal Volar Fracture combinations Isolated radius Radius with ulna

Ulnar styloid Ulnar physis

Ulnar metaphysis, incomplete Ulnar metaphysis, complete

Biomechanical patterns Torus

Greenstick One cortex Two cortices

Complete fracture Length maintained Bayonet apposition

Metaphyseal fracture patterns are classified as torus, incomplete or greenstick, and complete fractures (Fig. 8-17). This system of classification has been shown to have good agreement between experienced observers. 169 Torus fractures are axial compression injuries. The site of cortical failure is the transition frommetaph- ysis to diaphysis. 128 As the mode of failure is compression, these injuries are inherently stable and are further stabilized by the

A, B

C

Figure 8-17.  Metaphyseal biomechanical patterns. A: Torus fracture. Simple bulging of the thin cortex ( arrow ). B: Compression greenstick fracture. Angulation of the dorsal cortex ( large curved arrow ). The volar cortex is intact but slightly plastically deformed ( small white arrows ). C: Complete length maintained. Both cortices are completely fractured, but the length of the radius has been maintained. (Reprinted from Wilkins KE, ed. Operative Management of Upper Extremity Fractures in Children . Rosemont, IL: American Academy of Orthopaedic Surgeons; 1994:24, with permission.)

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CHAPTER 8 • Fractures of the Distal Radius and Ulna

Distal Ulna Fractures Isolated ulnar physeal fractures are rare, as most ulnar physeal injuries occur in association with radial metaphyseal or phy- seal fractures. 1,184 Physeal injuries are classified according to the Salter–Harris classification. 158 Ulnar physeal fractures may also be seen with the pediatric Galeazzi injuries, 171 which usually involve an ulnar physeal fracture rather than a soft tissue dis- ruption of the DRUJ. Avulsion fractures of the ulnar styloid also represent epiph- yseal avulsion injuries. Most commonly associated with distal radial fractures, 1,184 these styloid fractures typically represent soft tissue avulsions of the ulnar insertion of the TFCC or ulno- carpal ligaments 12 and are rarely associated with growth-related complications.

progressively elongates with advancing skeletal maturity. The secondary center of ossification for the distal ulna appears at about age 7 years. 149 Similar to the radius, the ulnar styloid appears with the adolescent growth spurt. It also becomes more elongated and adult-like until physeal closure. On average, the ulnar physis closes at age 16 in girls and age 17 in boys, whereas the radial physis closes on average 6 months later than the ulnar physis. 174,222 The distal radial and ulnar physes con- tribute approximately 75% to 80% of the growth of the forearm and 40% of the growth of the upper extremity (Fig. 8-18). 150 The distal radius articulates with the distal ulna at the DRUJ. 179 Both the radius and ulna articulate with the carpus, serving as the platform for the carpus and hand. The radial joint surface has three concavities for its articulations: the scaphoid and lunate fossa for the carpus and the sigmoid notch for the ulnar head. These joints are stabilized by a complex series of volar and dorsal radiocarpal, ulnocarpal, and radioulnar liga- ments. The volar ligaments are the major stabilizers. Starting radially at the radial styloid, the radial collateral, radioscapho- capitate, radiolunotriquetral (long radiolunate), and radios- capholunate (short radiolunate) ligaments volarly stabilize the radiocarpal joint. The dorsal radioscaphoid and radial triquetral ligaments are less important stabilizers. The complex structure of ligaments stabilize the radius, ulna, and carpus through the normal wrist motion of 120 degrees of flexion and extension, 50 degrees of radial and ulnar deviation, and 150 degrees of forearm rotation. 152 The TFCC is the primary stabilizer of the ulnocarpal and radioulnar articulations. 152 It extends from the sigmoid notch of the radius across the DRUJ and inserts into the base of the ulnar styloid. It also extends distally as the ulnolunate, ulnotriquetral, and ulnar collateral ligaments and inserts into the ulnar carpus and base of the fifth metacarpal. 152 The volar ulnocarpal liga- ments (V ligament) from the ulna to the lunate and triquetrum are important ulnocarpal stabilizers. 22,180 The central portion of the TFCC is the articular disk (Fig. 8-19). The interaction between the bony articulation and the soft tissue attachments accounts for stability of the DRUJ during pronation and supina- tion. 153 At the extremes of rotation, the joint is most stable. The compression loads between the radius and ulna are aided by the tensile loads of the TFCC to maintain stability throughout rotation. The interosseous ligament of the forearm (Fig. 8-20) helps stabilize the radius and ulna more proximally in the diaph- ysis of the forearm. The ulna remains relatively immobile as the radius rotates around it. Throughout the mid-forearm, the interosseous ligament connects the radius to the ulna. It passes obliquely from the proximal radius to the distal ulna. However, the interosseous ligament is not present in the distal radius. Moore et al. 142 found that injuries to the TFCC and interos- seous ligament were responsible for progressive shortening of the radius with fracture in a cadaveric study. The soft tissue component to the injury is a major factor in the deformity and instability in a Galeazzi fracture–dislocation. The length relationship between the distal radius and ulna at the wrist is defined as ulnar variance. In adults, this is mea- sured by the relationship of the radial corner of the distal ulnar articular surface to the ulnar corner of the radial articular

Galeazzi Fracture

Galeazzi Fractures: CLASSIFICATION

Type I: Dorsal (apex volar) displacement of distal radius Radius fracture pattern Greenstick Complete Distal ulna physis Intact Disrupted (equivalent) Type II: Volar (apex dorsal) displacement of distal radius Radius fracture pattern Greenstick Complete Distal ulna physis Intact Disrupted

Galeazzi fracture–dislocations are most commonly described by direction of displacement of either the distal ulnar dislocation or the radial fracture. 126 Letts preferred to describe the direc- tion of the ulna: volar or dorsal. 77,200 Others classified pediatric Galeazzi injuries by the direction of displacement of the distal radial fracture. Dorsally displaced (apex volar) fractures were more common than volarly displaced (apex dorsal) injuries in their series. Wilkins and O’Brien 211 modified the Walsh and McLaren method by classifying radial fractures as incomplete and complete fractures and ulnar injuries as true dislocations versus physeal fractures. DRUJ dislocations are called true Galeazzi lesions and distal ulnar physeal fractures are called pediatric Galeazzi equivalents. 109,121,126

PATHOANATOMY AND APPLIED ANATOMY RELATING TO FRACTURES OF THE DISTAL RADIUS AND ULNA

The distal radial epiphysis normally appears between 0.5 and 2.3 years in boys and 0.4 and 1.7 years in girls. 73,138,149 Ini- tially transverse in appearance, it rapidly becomes more adult- like with its triangular shape. The contour of the radial styloid

254

SECTION TWO • Upper Extremity

C

A

D

B

E

Figure 8-18.  Ossification of the distal radius. A: Preossification distal radius with transverse ossification in a 15-month-old boy. B: The triangular secondary ossification center of the distal radius in a 2-year-old girl. C: The initial ossification center of the styloid in this 7-year-old girl progresses radially ( arrow ). D: Exten- sion of the ulnar ossification center into the styloid process of an 11 year old. E: The styloid is fully ossified and the epiphyses have capped their relative metaphyses in this 13-year-old boy.

255

CHAPTER 8 • Fractures of the Distal Radius and Ulna

and wrist placed on the cassette, with the shoulder abducted 90 degrees, elbow flexed 90 degrees, and forearm in neutral rota- tion (Fig. 8-22). The importance of ulnar variance relates to the force transmission across the wrist with axial loading. Normally, the radiocarpal joint bears approximately 80% of the axial load across the wrist, and the ulnocarpal joint bears 20%. Changes in the length relationship of the radius and ulna alter respective load bearing. Indeed, 2.5 mm of ulnar positive variance has been demonstrated to double the forces borne across the ulnocarpal articulation in adult biomechanical analyses. 105,153 Biomechani- cal and clinical studies have shown that this load distribution is important in fractures, TFCC tears (positive ulnar variance), and Kienbock disease (negative ulnar variance). 4,75 The distal radius normally rotates around the relatively sta- tionary ulna. The two bones of the forearm articulate at the proximal radioulnar joints and DRUJs. In addition, proximally the radius and ulna articulate with the distal humerus and distally with the carpus. These articulations are necessary for forearm pronation and supination. At the DRUJ, the concave sigmoid notch of the radius incompletely matches the convex, asymmetric, semicylindrical shape of the distal ulnar head. 22,153 This allows some translation at the DRUJ with rotatory move- ments. The ligamentous structures are critical in stabilizing the radius as it rotates about the ulna (Fig. 8-23).

V

C

H

S

TQ

L

surface. 100 However, measurement of ulnar variance in chil- dren requires modifications of this technique. Hafner et al. 89 described measuring from the ulnar metaphysis to the radial metaphysis to lessen the measurement inaccuracies related to epiphyseal size and shape, a technique recently validated by Goldfarb et al. (Fig. 8-21). 80 If the ulna and radius are of equal lengths, there is a neutral variance. If the ulna is longer, there is a positive variance. If the ulna is shorter, there is a negative variance. Variance measurement is made in millimeters. Although not dependent on the length of the ulnar styloid, 22 the measurement of ulnar variance is dependent on forearm posi- tion and radiographic technique. 61 Radiographs of the wrist to determine ulnar variance should be standardized with the hand Figure 8-19.  Diagrammatic drawing of the TFCC and the prestyloid recess. The meniscal reflection runs from the dorsoulnar radius to the ulnovolar carpus. The arrow denotes access under the reflection to the tip of the styloid, the so-called prestyloid recess. V, fifth metacarpal; S, scaphoid; C, capitate; H, hamate; L, lunate; TQ, triquetrum. (Redrawn from Bowers WH. Green’s Operative Hand Surgery . New York: Churchill- Livingstone; 1993.)

TREATMENT OPTIONS FOR FRACTURES OF THE DISTAL RADIUS AND ULNA

NONOPERATIVE TREATMENT OF FRACTURES OF THE DISTAL RADIUS AND ULNA

The goal of pediatric distal radius fracture care is to achieve bony union within acceptable radiographic parameters to opti- mize long-term function and avoid late complications. Manage- ment is influenced tremendously by the remodeling potential of the distal radius in growing children (Fig. 8-24). In general, remodeling potential is dependent on the amount of skeletal growth remaining, proximity of the injury to the physis, and relationship of the deformity to plane of adjacent joint motion. Fractures in very young children, close to the distal radial physis, with predominantly sagittal plane angulation have the greatest remodeling capacity. Acceptable sagittal plane angu- lation of acute distal radial metaphyseal fractures has been reported to be from 10 to 35 degrees in patients under 5 years of age. 63,108,114,149,163,171,211 Similarly, in patients under 10 years of

Ulna

Interosseous membrane

Figure 8-20.  The attachment and the fibers of the interosseous membrane are such that there is no attachment to the distal radius. (Redrawn from Kraus B, Horne G. Galeazzi fractures. J Trauma . 1985;25:1094.)

Radius

256

SECTION TWO • Upper Extremity

A

A

B

B

Figure 8-21.  Hafner’s technique to measure ulnar variance. A: The distance from the most proximal point of the ulnar metaphysis to the most proximal point of the radial metaphysis. B: The distance from the most distal point of the ulnar metaphysis to the most distal point of the radial metaphysis. (Adapted by permission from Springer: Hafner R, Poznanski AK, Donovan JM. Ulnar variance in children. Standard mea- surements for evaluation of ulnar shortening in juvenile rheumatoid arthritis, hereditary multiple exostosis and other bone or joint disor- ders in childhood. Skel Radiol. 1989;18(4):513–516. Copyright © 1989 International Skeletal Society.)

Figure 8-22.  Technique for neutral rotation radiograph with wrist neutral, forearm pronated, elbow flexed 90 degrees, and shoulder abducted 90 degrees.

Volar

Dorsal

Dorsal

Volar

Volar

Dorsal

Pronation Midrotation Figure 8-23.  Distal radioulnar joint stability in pronation ( left ) is dependent on tension developed in the volar margin of the triangular fibrocartilage (TFCC, small arrowheads ) and compression between the contact areas of the radius and ulna (volar surface of ulnar articular head and dorsal margin of the sigmoid notch, large arrows ). Disruption of the volar TFCC would therefore allow dorsal displacement of the ulna in pronation. The reverse is true in supination, where disruption of the dorsal margin of the TFCC would allow volar displacement of the ulna relative to the radius as this rotational extreme is reached. The dark area of the TFCC emphasizes the portion of the TFCC that is not supported by the ulnar dome. The dotted circle is the arc of load transmission (lunate to TFCC) in that position. (Redrawn from Bowers WH. Green’s Operative Hand Surgery . New York: Churchill-Livingstone; 1993.) supination

257

CHAPTER 8 • Fractures of the Distal Radius and Ulna

Indications/Contraindications

age, the degree of acceptable angulation has ranged from 10 to 25 degrees (Table 8-1). 63,108,114,149,163,171,211 Criteria for what constitutes acceptable frontal plane deformity have been more uniform. The fracture tends to displace radially with an apex ulnar angulation. This defor- mity also has remodeling potential, 154,223 but less so than sag- ittal plane deformity. Most authorities agree that 10 degrees or less of acute malalignment in the frontal plane should be accepted. Greater magnitudes of coronal plane malalignment may not remodel and may result in limitations of forearm rotation. 42,44,54,62,210 In general, 10 to 30 degrees maximum of sagittal plane angulation, 10 to 15 degrees maximum of radioulnar deviation, and even complete bayonet apposition will reliably remodel in younger children with at least 2 years of significant growth remaining. 50,70,97,223

Nonoperative Treatment of Distal Radius Fractures: INDICATIONS AND CONTRAINDICATIONS Indications Relative Contraindications

Torus fractures Nondisplaced fractures Displaced fractures within acceptable radiographic alignment Displaced fractures amenable to closed reduction and immobilization Late-presenting physeal fractures Distal radial physeal stress fractures

Open fractures Neurovascular compromise or excessive swelling precluding circumferential cast immobilization

Irreducible fracture in unacceptable alignment Unstable fractures failing initial reduction and cast immobilization

A

Figure 8-24.  A: AP and lateral views of displaced radial physeal fracture. B: Healed malunion 1 month after radial physeal fracture.

( continues )

B

258

SECTION TWO • Upper Extremity

C

Figure 8-24.  ( Continued ) C: Significant remodeling at 5 months after fracture. D: Anatomic remodeling with no physeal arrest.

D

For the reasons cited above, most pediatric distal radius frac- tures can be successfully treated with nonoperative means (no reduction or closed reduction, cast immobilization). General indications for nonoperative treatment include torus fractures, displaced physeal or metaphyseal fractures within acceptable parameters of expected skeletal remodeling, displaced fractures with unacceptable alignment amenable to closed reduction and immobilization, and late-presenting displaced physeal injuries in which late closed reduction has high risk of growth arrest. Contraindications to nonoperative care include open frac- tures, fractures with excessive soft tissue injury or neurovascular compromise precluding circumferential cast immobilization, irre- ducible fractures in unacceptable alignment, unstable fractures failing initial nonoperative care, and fractures with displacement that will not remodel sufficiently to be acceptable long term.

TABLE 8-1. Angular Corrections in Degrees Sagittal Plane Age (yrs) Boys Girls

Frontal Plane

4–9

20

15

15

9–11

15

10

5

11–13

10

10

0

> 13

5

0

0

Acceptable residual angulation is that which will result in total radiographic and functional correction. (Courtesy of B. De Courtivron, MD. Centre Hospitalie Universitaire de Tours. Tours, France.)

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CHAPTER 8 • Fractures of the Distal Radius and Ulna

A

B

Figure 8-25.  Anteroposterior ( A ) and lateral ( B ) radiographs of a distal radius torus fracture.

Splint Immobilization of Torus Fractures By definition, torus fractures are compression fractures of the distal radial metaphysis and are therefore inherently stable (Fig. 8-25). There is typically minimal cortical disruption or displacement. As a result, treatment should consist of pro- tected immobilization to prevent further injury and relieve pain. Multiple studies have compared the effectiveness and cost of casting, splinting, and simple soft bandage applica- tion in the treatment of torus fractures. As expected, there is little difference in outcome of the various immobilization techniques. 2,21,102,147,163,173,182,207 Davidson et al. 43 randomized 201 children with torus fractures to plaster cast or removable wrist splint immobili- zation for 3 weeks. All patients went on to successful healing without complications or need for follow-up clinical visits or radiographs. Similarly, Plint et al. 161 reported the results of a prospective randomized clinical trial in which 87 children were treated with either short-arm casts or removable splints for 3 weeks. Not only were there no differences in healing or pain, but also early wrist function was considerably better in the splinted patients. West et al. 209 even challenged the need for splinting in their clinical study randomizing 39 patients to either plaster casts or soft bandages. Again, fracture healing was universal and uneventful, and patients treated with soft ban- dages had better early wrist motion. Given the reliable healing seen with torus fracture healing, Symons et al. 186 performed a randomized trial of 87 patients treated with plaster splints to either hospital follow-up or home removal. No difference was seen in clinical results, and patient/ families preferred home splint removal. A similar study by Khan et al. 115 confirmed these findings. No differences in outcomes

were seen in 117 patients treated with either rigid cast removal in fracture clinic versus soft cast removal at home, and families preferred home removal of their immobilization. A meta-analysis of torus and minimally displaced fractures treated by removable splints instead of circumferential casts was found to have improved secondary outcomes for the patient and family and with equal position at healing. 11 SCAMPs (Stan- dardized Clinical Assessment and Management Plans) work from Boston Children’s Hospital has indicated that reduction in casting and postinjury radiographs, coupled with phone call follow-up visits, have lessened direct and indirect costs, radi- ation and cast saw injury risk significantly, with no change or improved outcome for torus fractures. 130,131 Therefore, simple splinting is sufficient, and once the patient is comfortable, range-of-motion exercises and nontrau- matic activities may begin. Fracture healing usually occurs in 3 to 4 weeks. 2,10 Simple torus fractures heal without long-term sequelae or complications.

Cast Immobilization of Nondisplaced or Minimally Displaced Distal Radial Metaphyseal and Physeal Fractures

Nondisplaced fractures are treated with cast immobilization until appropriate bony healing and pain resolution have been achieved. 47,52,175 Although these fractures are radiographically well aligned at the time of presentation, fracture stability is dif- ficult to assess and a risk of late displacement exists (Fig. 8-26). Serial radiographs are obtained in the first 2 to 3 weeks pos- treduction to confirm maintenance of acceptable radiographic alignment. In general, most fractures will heal within 4 to 6 weeks.