Introduction: Scope and Purpose
Upper extremity injury is one the most common presenting complaints after trauma in the pediatric population. Fractures of the forearm represent 40% of fractures in all age groups of children. Upper extremity fractures and dislocations are slightly more common in boys than in girls. There is a higher incidence from ages 4 to 14 years as children begin to independently interact with their environment and participate in recreational and competitive sporting activities. The most common injuries are to the distal metaphyseal and physeal region of the forearm. Diaphyseal fractures remain more common in prepubescent children, whereas physeal injuries are more common among adolescents. Fractures of the carpus are far less common. Frequently, these are subtle injuries that are initially overlooked. Hand injuries remain common and are most often due to direct trauma, such as crush injuries in the young and sports injuries in the school-age and adolescent athlete.
Mechanism of Injury/Biomechanics
It is important to understand the mechanism of injury and regional anatomy of the injured upper extremity to appreciate the resultant deformity and make appropriate treatment decisions. This understanding is necessary for correcting the deformity and preventing complications. In fractures of the distal radius and ulna, the three-dimensional location of the torn periosteum influences reduction maneuvers. In the diaphyseal forearm, the angular and rotational deformities guide reduction techniques. Interposed periosteum, muscle, or tendon may block reduction of fractures.
Mechanism of Diaphyseal Forearm Fractures
Fractures of the forearm in children often result from a fall on an outstretched hand. This results in forceful axial loading with resultant bony failure in compression and bending. These forces can cause plastic deformation, partial (greenstick) fracture, or complete fractures, usually of both the radius and ulna. Any fracture of a single bone of the forearm from a fall should be considered unusual and is highly suggestive of an associated injury to the proximal or distal radioulnar articulations or plastic deformation of the other bone. Single bone injuries are more characteristic of a direct blow, such as striking the ulna with an object such as a baseball bat. In addition to excessive axial loading, falls on an outstretched hand also result in forceful rotation of the forearm with resultant rotational deformity. This usually results in a supination deformity and apex volar angulation. The rotational malalignment may be unappreciated and undertreated. It is generally accepted that rotational deformities have little to no potential for remodeling, even in very young children. Thus a failure to diagnose and correctly treat rotational malalignment is the most common cause of permanent loss of forearm rotation in children.
Mechanism of Fractures of the Distal Radius
Fractures of the distal radius comprise approximately one third of all fractures in children. In the past 40 years, their incidence has increased, likely secondary to increased participation in sports or increased body weight. The mechanism of injury is usually a fall on an outstretched hand, similar to diaphyseal forearm fractures.
Mechanism of Carpal Fractures
Carpal fractures are uncommon in children. Similar to adults, the scaphoid remains the most fractured carpal bone in children, representing only 0.45% of all fractures in the pediatric population. Also similar to adult distributions, the scaphoid waist fracture is the most common (71%), followed by distal pole fractures representing 23% and proximal pole fractures comprising the remaining 6%. Carpal fractures are often missed in children on initial presentation; hence the treating physician must maintain a high index of suspicion to accurately make the diagnosis in a timely fashion. The mechanism of injury remains a fall on an outstretched hand.
Mechanism of Hand Fractures
Multiple mechanisms are responsible for hand fractures in children. Phalangeal fractures are the most common hand fractures in children ; metacarpal fractures are relatively rare. The most common mechanisms for hand fractures in children include jamming injuries in sports, crush injuries, and direct blow injuries.
Evaluation
Obtaining a thorough history is critical for the accurate diagnosis of these injuries. This can be difficult in small children, thus making an interview with parents or any witnesses to the injury essential. Unwitnessed injuries in nonverbal children may yield no available history. Clear details on the mechanism of injury are integral to understanding the deformity, energy of the injury, and the likelihood of associated injuries. To protect children in cases of abuse, physicians should always consider the plausibility and consistency of the history.
Examination
Physical examination is an integral part of deformity assessment. In addition to angular deformities, subtle rotational deformities should not be overlooked, and comparison with the unaffected limb is essential. In addition to the bony deformity, thorough examination of the shoulder, elbow, wrist, and hand must be completed to rule out concomitant injuries. Assessment of the soft tissues is important, particularly in higher energy and open fractures. Serial evaluations over several days may be necessary to fully appreciate the extent of associated soft tissue injuries in rare, major trauma situations. Compartment syndrome must be considered in all fractures and instances of severe soft tissue injury, such as crush or burn injuries. The three A s of compartment syndrome in children—agitation, anxiety, and analgesics—should be evaluated in all injuries at risk of development of compartment syndrome. Measurement of compartment pressures may be necessary in nonverbal or obtunded children. A careful prereduction and postreduction neurovascular assessment is mandatory, and frequent serial assessment is prudent. Open fractures and concomitant fractures of the same limb have the highest risk.
Imaging
Plain radiography remains the gold standard for musculoskeletal evaluation and should be completed in all patients with a physical examination suggestive of a fracture or dislocation. Biplanar radiographs demonstrate most fractures and dislocations. However, the limitations of two-dimensional evaluation of three-dimensional deformities are real and can result in a failure to clearly illustrate nondisplaced fractures, subtle dislocations, and malrotation injuries. Oblique radiographs can greatly aid in such diagnoses. Rotational deformities can be especially difficult to assess by plain radiography. Loss of anatomic bow or diameter mismatches may suggest such deformity. True anteroposterior and lateral views are requisite, whereas oblique and specially tailored views often aid in diagnosis. At a minimum, the joint above and below the injury should be clearly imaged. Suboptimal films are not acceptable and must be repeated. Magnetic resonance imaging (MRI) has emerged as a useful adjunct for evaluating soft tissues, diagnosing occult fractures (e.g., scaphoid fractures), and assessing cartilaginous injuries to the immature skeleton. Computed tomography (CT) remains the study of choice for detailed evaluation of bony anatomy, such as intraarticular fractures. A bone scan is a safe and reliable method for the diagnosis of occult fractures, but MRI has largely supplanted its use in the recent past. MRI and CT arthrograms can be invaluable in evaluation of joints, particularly in small children whose nonossified epiphyses can be difficult to evaluate by plain radiographs.
Classification
The Arbeitsgemeinschaft fur Osteosynthesefragen (AO) system or the Orthopaedic Trauma Association (OTA)-type fracture classification systems have not gained widespread use in describing upper extremity fracture patterns in pediatric patients. Instead, by convention they are described on the basis of (1) which bone or bones are involved, (2) fracture location (e.g., diaphyseal, metaphyseal, epiphyseal), (3) direction of displacement (e.g., apex volar), (4) physeal involvement (e.g., Salter–Harris classification), (5) articular involvement, and (6) failure mode (e.g., plastic deformation, partial or greenstick fracture, or complete fracture).
The biomechanical properties of bone in children differ from that in adults. Immature bone is more elastic and has a greater ability to deform without fracture. As a result, excessive mechanical loading of immature bone can result in a spectrum of pathologic change, including plastic deformation, greenstick fracture, and complete fracture. Each of these can result in clinically significant deformity. Combinations of these injuries are common and must be recognized (e.g., complete fracture of the radius with concomitant greenstick fracture of the ulna).
Plastic Deformation
Immature bone has greater elasticity. In children, bone may deform under loading with a resultant angular deformity but no actual cortical disruption ( Fig. 9-1 ). Thus the fracture may not be obvious radiographically. Rather, only the contour of the bone has changed. These injuries can range in severity from subtle and clinically insignificant to a complete loss of anatomic bow with permanent loss of forearm rotation if left untreated. Such deformities can be easily overlooked by the untrained eye and must always be suspected, particularly in cases of single-bone forearm fractures. Generally, a plastic deformation injury with restricted forearm pronation and supination requires a reduction with conscious sedation or general anesthesia. Considerable reduction force is required and applied over a solid bolster for several minutes ( Fig. 9-2 ).
Partial (Greenstick) Fractures
The elasticity of bone in children also explains its greater tendency for partial or unicortical fracture. Greenstick fractures are characterized by incomplete cortical fracture with angulation and rotation through plastic deformation of the remaining intact cortex. These fractures are commonly seen in children and are often noted in conjunction with a complete fracture of the other bone of the forearm. Diaphyseal fractures of the forearm are usually apex volar supination injuries ( Fig. 9-3 ). Greenstick fractures are primarily a rotational deformity, although the radiographs are commonly misinterpreted as an angular deformity. As with any fracture, the degree of angular and rotational deformity must be assessed and treated accordingly. Apex volar fractures are supination deformity injuries requiring pronation for reduction. Conversely, less common apex dorsal fractures are pronation deformity injuries requiring supination for reduction. Greenstick fracture patterns are inherently more stable than complete fracture patterns after reduction. As such, they are usually treated with cast immobilization in the appropriate corrective rotation with molding to maintain the interosseous space and a straight ulnar border.
The greater mechanical stability of greenstick fractures may also result in greater difficulty when a reduction is required. In the case of both-bone forearm fractures, greenstick fracture of the ulna in association with a complex fracture of the radius may act not only as a contributor to the deformity but also as a potential block to reduction. Several authors have advocated “completion” of the greenstick fracture to facilitate the ease of reduction. Others have suggested that this is not necessary and adds unwanted instability to the fracture. Long-term data on this subject are lacking, and this approach remains controversial. Most would agree that the completion of greenstick fractures is acceptable and appropriate when necessary for achieving an anatomic reduction.
Complete Fractures
Greater force of injury results in the complete disruption of cortical bone. In the forearm, this typically involves both bones but may involve a single bone in conjunction with greenstick fracture or plastic deformation of the other. True single-bone forearm fractures do occur and are typically the result of a direct blow. Single-bone forearm fractures in the setting of an axial load are rare and should raise the suspicion of an injury to the proximal or distal radioulnar joint (e.g., Monteggia or Galeazzi fracture, respectively) ( Fig. 9-4 ). Complete fractures usually occur in older children and are inherently more unstable after reduction.
Management
Diaphyseal Forearm Fractures
Emergent Treatment
The need for emergent treatment of diaphyseal forearm fractures is rare. Those fractures that are open, associated with a neurovascular injury, or are complicated by a developing compartment syndrome qualify for true emergent treatment. Otherwise, most forearm fractures can be treated with appropriate urgency to stabilize the injury. This can be completed temporarily with a splint in the emergency department before evaluation for definitive management.
Indications for Definitive Care
The goals of treatment include the safe and expedient correction of bony malalignment and rotation to as anatomic position as possible within acceptable standards of anticipated remodeling, anatomic reductions of joint dislocations, maintenance of reduction until adequate healing has occurred, and appropriate treatment of soft tissue injuries. Nondisplaced stable fractures are treated with brief immobilization for comfort and prevention of recurrent injury during the healing phase. Displaced fractures and dislocations in the forearm are most often treated with closed reduction and cast immobilization. Operative intervention is indicated when adequate reduction cannot be achieved or maintained by closed means. Frequently used methods depending on the clinical situation include closed reduction and percutaneous pinning, percutaneous or open intramedullary rodding, and open reduction–internal fixation with the use of plates and screws. External fixation is less commonly used in children.
Proximal forearm fractures are a challenge to treat. Closed reduction can be difficult because the margin for acceptable malalignment is narrow. Isolated injuries to the proximal radius or ulna are rare. They should be suggestive of associated fractures or dislocations. A high level of suspicion should be maintained for associated dislocation, physeal separation, or plastic deformation of the adjacent bone. Missed diagnoses in the proximal forearm often lead to chronic deformity with long-term consequences and inferior outcomes. Nondisplaced fractures of the proximal radius and/or ulna in younger children can be treated in a cast. A well-molded long arm cast is most appropriate for children younger than 5 years. Angulation greater than 10° to 15° in the proximal portion of the radius or ulna is unacceptable because of the risk of loss of forearm rotation with malunion. The remodeling potential of the proximal radius is limited. Distal insertions of the biceps, brachialis, and supinator muscles on the proximal radius generate strong deforming forces with resultant flexion and supination of the proximal radial fragment, whereas the triceps can cause extension of the proximal ulna.
Many diaphyseal fractures of the radius and ulna are amenable to treatment by closed means. Nondisplaced fractures are best treated with a well-placed long arm cast. Displaced, incomplete fractures in younger children can be treated with closed reduction and casting. Generally, postreduction malalignment beyond 20° is unacceptable. Bayonet apposition without malangulation or malrotation may remodel in children younger than 8 to 10 years in distal fractures because of their proximity to the physes. However, in older adolescents with displaced complete fractures, remodeling potential is less, and these patients are often best treated, as adults would be, with plate and screw fixation. A spectrum of fracture types and instability exists between these two extremes. In younger children with unstable fractures that are not amenable to closed reduction and casting, intramedullary fixation with heavy Kirschner wires or flexible rods is an effective, less-invasive technique.
Nonoperative Treatment
The majority of fractures and dislocations involving the forearm can be treated nonoperatively. The rapid healing, the remodeling potential of children’s bones in the planes of motion of the adjacent joints, and their tolerance for immobilization make cast-splint management the treatment of choice in most cases. Proper technique in reduction and immobilization is critical for successful treatment.
Displaced fractures, dislocations, and fracture–dislocations require reduction before immobilization. Manual manipulation of the extremity can range from gentle traction to vigorous and forceful re-creation of the injury mechanism for deformity correction, depending on the fracture location and degree of deformity. Determining whether a fracture reduction is necessary is of paramount importance. This decision is based on acceptable standards reported in the literature for expected specific injury outcomes as they relate to fracture displacement, joint dislocation or subluxation, fracture location (i.e., metaphyseal, diaphyseal, or epiphyseal), and the potential for remodeling (i.e., skeletal age of the patient, proximity to an open physis, and the plane of deformity relative to that of the proximate joints).
Once the determination has been made that the present fracture alignment is unacceptable, the patient is prepared for a reduction maneuver. In most children, this requires some level of anesthesia. In smaller children, this may be in the form of conscious sedation administered in the emergency department setting. This usually entails a combination of analgesic and amnestic medications such as ketamine, narcotics, and/or benzodiazepines. Conscious sedation should only be administered to children in a monitored setting by an experienced pediatrician or anesthesiologist who is certified in pediatric advanced life support (PALS). Oxygen, reversal agents, and equipment for emergency airway management must be made available before administration of sedation. For more complex cases or anticipated prolonged procedures, formal administration of a general anesthetic in the operating room is considered to be safer and a more controlled option. Adolescents approaching adulthood may not require sedation for closed reductions, particularly of distal radial metaphyseal and physeal fractures. A hematoma block or intrafracture local anesthetic injection may suffice for closed reductions in the emergency department in this age group.
Once the patient is adequately and safely sedated or anesthetized, the reduction maneuver is performed. Proper technique is essential for a successful reduction. The techniques used for reduction maneuvers vary greatly, depending on the specific injury pattern. However, some general principles apply to all reduction maneuvers. The patient must be positioned in such a way as to provide the surgeon optimal mechanical advantage and access to the extremity. Aid from a qualified assistant can be invaluable and should be sought if and when resources allow. Prereduction and postreduction neurovascular examination and documentation should be considered part of every reduction maneuver. Portable image intensification should be used when available. Casting or splinting materials should be collected and prepared as completely as possible before reduction. Some surgeons prefer to apply stockinette or even cast padding before reduction in an effort to minimize the risk of loss of reduction during cast application. The surgeon must then be prepared to safely apply the necessary amount of force to achieve reduction. This may range from only gentle axial traction to forceful manipulation. An understanding of the exact amount of force that is both necessary and safe is gained only by practical experience and reduction maneuvers performed under supervision whenever possible. In children, a partially intact layer of periosteum may act as a tether that indirectly blocks reduction, necessitating the re-creation of the injury mechanism with intentional exaggeration of angulation to “unhook” the fracture. This allows subsequent unfettered rotation at the fracture site around a hinge of intact periosteum. When the correct technique is used to unhook the fracture, this hinge of periosteum can act as an aid in reduction by preventing complete displacement, guiding the reduction to a more anatomic position, and adding stability to the injury pattern as a tension band. Attempts should be made to keep any remaining periosteum intact. The “three point” cast molding technique exploits the fulcrum created by the partially intact periosteum to provide added stability to the reduction and subsequent immobilization. Muscle spasm and contracture may contribute to fracture deformity. Relaxation can be achieved by steady longitudinal traction applied over time, which eventually results in muscle fatigue and gradual lengthening. Older children may tolerate elevation in finger traps with 5 to 10 pounds of weight suspended around the upper arm. Intravenous muscle relaxants are rarely necessary. The goal of closed reduction is anatomic alignment with correction of translation, malrotation, and malangulation. This lessens the risk of unacceptable loss of reduction over the ensuing 3 to 4 weeks of fracture healing.
Unacceptable reduction is generally considered to be greater than 20° malangulation with 2 years or less of growth remaining. However, in the proximal forearm, malalignment of greater than 10° to 15° may not remodel and thus impair forearm rotation permanently. Bayonet apposition has been thought to be acceptable up to 8 to 10 years of age, as long as malangulation and malrotation are corrected. In the case of unexpectedly difficult reductions, the surgeon must entertain the possibility of interposed tissues such as periosteum, muscle, tendon, or neurovascular structures. Interposed structures may render anatomic reduction impossible, necessitating surgical exploration. Particular caution is necessary when reduction of displaced physeal fractures is attempted. This should be limited to one or two gentle closed reduction attempts, and forceful manipulation of the physis should be avoided, if possible. Repeated attempts at reduction of physeal injuries may result in iatrogenic physeal injury and growth arrest.
The majority of forearm fractures, whether proximal or diaphyseal, should be immobilized in a long arm cast or splint. Important molding characteristics include (1) well-contoured supracondylar humeral molds, (2) well-contoured interosseous forearm molds, (3) three-point molding techniques, (4) allowance of appropriate elbow flexion, and (5) a straight ulnar border. If circumferential casting is the preferred immobilization technique, the cast should be bivalved to allow for swelling of the extremity. Poor casting technique can result in unnecessary loss of reduction and can place the patient at higher risk of cast-related complications such as skin breakdown and cast-saw burns ( Fig. 9-5 ).
Nondisplaced fractures should be casted with the elbow in 90° of flexion and the forearm in neutral rotation. Displaced fractures requiring reduction should also be casted with the elbow flexed 90°, but forearm rotation may be one of supination or pronation (more common), depending on the fracture pattern and the stable position after reduction. Cast immobilization is usually continued for 4 to 6 weeks, depending on evidence of radiographic healing. Frequent radiographs, usually weekly for up to 3 weeks, should be obtained for fractures requiring reduction so that acceptable alignment is maintained.
Surgical Treatment
Surgical treatment of forearm fractures is reserved for those fractures that are irreducible by closed means or that fail closed management because of loss of reduction, open fracture type, or compartment syndrome complications.
Surgical Anatomy
Development
A thorough understanding of the development of the radius and ulna and their articulation is essential for treating injuries to the growing forearm. Familiarity with normal ages of ossification and locations of all secondary growth centers, as well as the expected growth potential and age at fusion of all physes, is also essential for the protection of the immature physis and nonossified epiphyses when injuries are being treated. It is important to note that epiphyses form initially as cartilaginous structures, only to ossify secondarily with further growth. It is critical to remain cognizant of the fact that these structures can be significantly injured before ossification and radiographic evidence of injury.
The radius and ulna form from primary ossification centers that appear during the eighth week of gestation. Secondary ossification centers, or epiphyses, later begin to ossify at the proximal end of the radius in the fifth to seventh year and in the proximal ulna in the ninth to tenth years. The distal epiphysis of the radius ossifies during the first year in girls and shortly after 1 year in boys. The distal ulnar epiphysis, however, does not begin to ossify until approximately age 6 in boys and girls ( Table 9-1 ). It is important to note that either the distal radial or ulnar epiphyses may occasionally develop from two distinct ossification centers and should not be mistaken for fracture of the radial or ulnar styloids. Distal radial and ulnar physes typically fuse in the sixteenth to eighteenth year. Girls’ physes generally fuse earlier than boys’.
| OSSIFICATION | PHYSEAL CLOSURE | |||
|---|---|---|---|---|
| GROWTH CENTER | BOYS | GIRLS | BOYS | GIRLS |
| Proximal radius | 5–7 | 5–7 | 16–18 | 16–18 |
| Distal radius | 1–1.5 | <1 | 18–19 | 17 |
| Proximal ulna | 9–10 | 9–10 | 16–18 | 16–18 |
| Distal ulna | 6 | 6 | 17–18 | 16–17 |
| Primary radius | 8 weeks | 8 weeks | ||
| Primary ulna | 8 weeks | 8 weeks | ||
Osteology
The forearm is composed of the radius and ulna. They articulate with one another at both the proximal (PRUJ) and distal radioulnar joints (DRUJ). The interosseous membrane provides a fibrous attachment between the two bones along their length ( Fig. 9-6 ). At the elbow, the radius and ulna articulate with the capitellum and the trochlea of the humerus, respectively. At the wrist, the radius and ulna articulate with the proximal row of the carpus (i.e., scaphoid, lunate, and triquetrum from radial to ulnar). In cross section the radius is cylindrical proximally, becomes triangular in its middle third, and is more broad and elliptical distally. The radius has a physiologic bow in the radial and posterior direction with the forearm in supination, which creates the interosseous space, and is critical for forearm rotation. It is stabilized proximally by the annular ligament, the PRUJ and the quadrate ligament, proximal fibers of the interosseous membrane, lateral collateral ligaments of the elbow, and the osseous constraints of the radiocapitellar joint. The radial head and radial styloid are palpable proximally and distally, respectively. Just distal to the radial neck, the biceps tendon attaches to the bicipital tuberosity, which points anteriorly in supination and posteriorly in pronation. This can be a useful landmark radiographically for assessing rotational deformities and loss of the anatomic bow. The Lister tubercle is a dorsal prominence on the distal aspect of the radius, which can also serve as a useful landmark clinically and radiographically. The extensor pollicis longus (EPL) passes around the Lister tubercle and can be injured by fracture fragments or internal fixation techniques. The ulna is triangular in cross section and has a straight border and small posterior bow in its proximal third. It is statically stabilized proximally by the osseous constraints of the trochlea, the PRUJ, and the medial and lateral collateral ligaments of the elbow. The coronoid and olecranon processes form the trochlear notch of the ulna, providing the osseous stability of the ulnohumeral articulation. Distally, the ulna is stabilized by the DRUJ and the attachments of the triangular fibrocartilage complex (TFCC). The ulnar styloid is a palpable prominence at the distal ulnar aspect of the ulna.
Proximal Radioulnar Joint
The head of the radius sits in the radial notch of the ulna. It is stabilized in this position by the annular ligament, which encases the radial head nearly circumferentially, and has fibrous attachments both to the ulna and to the medial and lateral collateral ligaments of the elbow. The joint capsule and the oblique cord, which runs from the base of the coronoid process to just distal to the radial tuberosity, provide additional stability. The quadrate ligament is a stout and flat band that lies deep to the annular ligament on the anterior aspect of the PRUJ, extending from the base of the coronoid to the radial neck. Similar to the interosseous membrane, it tightens with supination of the radius, stabilizing the radial head in the notch of the ulna. Finally, during supination, the broadest area of the radial head is in contact with the radial notch of the ulna. It is for these reasons that the PRUJ is most stable in forearm supination. Injury to these structures can be seen in Monteggia fractures, elbow dislocations, and radial head fracture–dislocations.
Interosseus Membrane
This flat, fibrous layer runs from the medial border of the radius to the lateral border of the ulna. It extends from a level 1 cm distal to the radial tuberosity distally to the DRUJ. The obliquely oriented fibers run from the radius directed distally to the ulna at an angle of approximately 60°. The membrane is most taut in neutral to 30° of supination and relaxes in pronation and terminal supination. The interosseous membrane is important in the mechanics of forearm rotation, stabilization of the PRUJ, and in resistance of proximal migration of the radius relative to the ulna. It also serves as a useful surgical landmark for demarcating the anterior and posterior compartments of the forearm. The Essex-Lopresti lesion is characterized by radial head fracture with associated rupture of the interosseous membrane. In these injuries the DRUJ can be injured or unstable because of loss of bone and soft tissue constraints related to proximal migration of the radius.
Distal Radioulnar Joint
The volar and dorsal radioulnar ligaments, the ulnar collateral ligament of the wrist, and the attachments of the TFCC stabilize the DRUJ. The carpal ligaments contribute stability to the DRUJ and will be discussed under anatomy of the wrist. It is important to understand the relationship between the DRUJ and the TFCC and to recognize that an injury to one often suggests an injury to the other.
The TFCC consists of the triangular fibrocartilage and the ulnocarpal ligaments, serving as an important stabilizer of the DRUJ and ulnar aspect of the wrist. It also serves as a cushion to ulnotriquetral impaction during ulnar deviation of the wrist. The TFCC is a fibrocartilaginous disk similar to the meniscus of the knee. It is thicker and more vascular at its periphery but thinner and relatively avascular near its center. It has strong attachments to the volar and dorsal radioulnar ligaments and the ulnar collateral ligament of the wrist. At the periphery, it has attachments to the joint capsule. It spans the DRUJ, separating the carpal articular surface from the notch of the ulna. Extending from the ulnar aspect of the radial articular surface, it covers the distal aspect of the ulna with peripheral attachments at the joint capsule, the base of the ulnar styloid, and the ulnar collateral ligament of the wrist.
Injuries to the DRUJ may occur in isolation or may be seen in combination with a fracture such as in a Galeazzi fracture (DRUJ dissociation with radial shaft fracture) or Essex-Lopresti lesions (DRUJ injury in association with radial head fracture and interosseous membrane disruption).
Forearm Rotation
With forearm rotation, the radius rotates, or “radiates,” around the ulna and around a longitudinal axis centered through the radiocapitellar joint proximally and the center of the ulna distally. Rotation of the radius about the ulna has been described as forming a half-cone of approximately 150° to 180°. The radial head pivots within the annular ligament. With forearm supination, the quadrate ligament tightens across the anterior aspect of the PRUJ, and the volar radioulnar ligament tightens across the DRUJ.
It is critical to understand the significance of the interosseous space and membrane in forearm rotation. Cadaveric studies have shown that the diameter of the interosseous space and the tension across the interosseous membrane change with forearm rotation. At neutral to 30° of supination, the interosseous space is at its greatest diameter and the membrane is most taut. The interosseous space decreases with pronation and at extremes of supination, and the membrane tension decreases accordingly. The radial bow is normally in the radial and posterior direction. A loss of this anatomic bow can effectively decrease the diameter of the interosseous space ( Fig. 9-7 ). As a result, significant pronation may be lost secondary to radioulnar impingement at terminal pronation. The most common cause of loss of range of motion after a forearm fracture is a loss of rotation secondary to a failure to restore the anatomic bow of the radius. In malreduced proximal fractures, the bicipital tuberosity may impinge on the ulna.
Positioning Techniques
For procedures performed on the forearm, the patient is best positioned supine on the operating room table with the injured extremity extended onto a hand table. A tourniquet is useful for obtaining a bloodless operative field. Surgeon preference denotes the use of a sterile versus a nonsterile tourniquet across the upper brachium. The image intensifier is often placed perpendicular to the operating room table and parallel to the operative extremity to allow the surgeon and an assistant unimpeded access to the operative field.
Surgical Approach
Anterior (Henry) Approach to the Radius
The anterior approach to the forearm, also commonly referred to as the Henry approach ( Table 9-2 ), is a workhorse for the upper extremity surgeon ( Fig. 9-8 ). This extensile approach provides excellent exposure of the radius from the wrist to the elbow. It may also be extended across the elbow and carried proximally in the anterior approach to the upper arm and shoulder. Theoretically, the upper extremity osseous structures can be exposed from the wrist to the shoulder through one incision with the use of this approach. Five muscles must be detached from the anterior aspect of the radius to expose it in its entirety. From proximally to distally, they are the supinator, pronator teres, flexor digitorum superficialis, flexor pollicis longus, and pronator quadratus.
| APPROACH | MUSCULAR INTERVAL | INTERNERVOUS PLANE | DANGERS |
|---|---|---|---|
| Anterior radius | Proximal: pronator teres and brachioradialis | Median and radial nerves | PIN, superficial radial nerve, radial artery |
| Distal: FCR and brachioradialis |
The anterior approach to the forearm exploits the internervous plane between the median and radial nerves. Proximally, this plane lies between the pronator teres (median nerve) and brachioradialis (radial nerve) muscles. Distally, the plane is between the flexor carpi radialis (FCR) (median nerve) and the brachioradialis. For incision location, the brachioradialis muscle and mobile wad are palpated on the radial forearm. Just medial to the brachioradialis and lateral to the biceps tendon, a linear longitudinal incision is initiated just distal to the elbow flexion crease and is carried distally toward the insertion of the FCR tendon, in line with the radial shaft. The dissection is carried down to the subcutaneous fascia. The lateral antebrachial cutaneous nerve may be visualized in the proximal aspect of the wound and must be protected.
In the proximal third, the interval between the pronator teres and the brachioradialis is identified. The fascia is incised in line with these fibers, and the interval is bluntly defined. A collateral branch of the radial artery, known as the recurrent leash of Henry, is often encountered in this interval and must be ligated so that the brachioradialis can be mobilized laterally. The radial artery can then be retracted medially. The next muscle encountered is the supinator, which is easily identified by the transverse course of its fibers. Great care must be taken during this portion of the exposure to avoid injury to the posterior interosseous nerve (PIN). The radial nerve, which runs between the brachialis and brachioradialis muscles in the distal humerus, branches just below the elbow into the superficial (sensory) and posterior interosseous (motor) branches. The superficial branch continues distally between the brachioradialis and extensor carpi radialis longus (ECRL) muscles and should be mobilized laterally with the brachioradialis. It pierces the fascia to become subcutaneous roughly 5 to 7 cm above the wrist. The PIN travels medially and posteriorly, passing under the fibrous leading edge of the supinator, known as the arcade of Frohse, and splitting the two heads of the supinator muscle. Not all patients have two heads of the supinator muscle; thus the nerve can lie directly on the periosteum, where it is at greatest risk of injury. It then traverses the muscle, wrapping posteriorly around the radial neck and proceeding distally across the origin of the abductor pollicis longus (APL) muscle along the posterior aspect of the interosseous membrane. It is also at this level that the PIN is at greatest risk of injury during the anterior approach. It runs in very close proximity to the radius at this level and may be difficult to visualize through the supinator. Supination of the forearm will move the PIN radially and posteriorly, displacing it from the incision and protecting it. The insertion of the supinator on the radius is then identified and elevated in a subperiosteal fashion, moving circumferentially from medial to lateral, and carefully posteriorly around the radial neck. It is critical that the supinator be elevated subperiosteally to protect the PIN. Even gentle retraction of the supinator on the radial aspect of the radius can result in neurapraxia of the PIN and should be avoided whenever possible. Blind placement of retractors on the radial and posterior aspect of the proximal radius puts the nerve at risk and is not recommended. Subperiosteal exposure of the radius can then be safely carried distally.
The anterior middle third of the radius is covered by the insertion of the pronator teres and the origin of the flexor digitorum superficialis (FDS) tendons. Pronation of the forearm at this point exposes the lateral insertion of the pronator on the radius. The pronator and FDS can then be elevated from proximal to distal in a subperiosteal fashion. Distal to the pronator teres insertion the superficial plane lies between the brachioradialis and the FCR. Many surgeons incise the floor of the sheath of the FCR tendon longitudinally. The radial artery is identified and usually mobilized laterally. This reveals the pronator quadratus and flexor pollicis longus attachments to the anterior aspect of the distal radius. With the forearm once again in supination, these muscles can be detached subperiosteally from the lateral aspect of the radius and retracted medially, providing excellent exposure of the distal third of the radius. A cuff of tissue should be preserved to allow repair of these muscles, whenever possible.
Anterior Exposure of the Ulnar Nerve
Occasionally, exploration of the ulnar nerve may be necessary in the forearm ( Table 9-3 and Figs. 9-9 and 9-10 ). It is useful for the upper extremity surgeon to be comfortable with this approach and to be knowledgeable of the course of the major nerves in the forearm. This approach exploits the space between the flexor carpi ulnaris (FCU) (ulnar nerve) and the FDS (median nerve). The ulnar nerve provides motor innervation to the FCU and the ulnar half of the flexor digitorum profundus (FDP) in the forearm and can be found lying between these two muscles running medial to the ulnar artery. Proximally in the upper arm, the ulnar nerve pierces the intermuscular septum from anterior to posterior to travel posterior to the medial epicondyle at the elbow, traveling beneath the leading edge of the FCU. Distally at the wrist, the ulnar nerve traverses the wrist through the Guyon canal.
| APPROACH | MUSCULAR INTERVAL | INTERNERVOUS PLANE | DANGERS |
|---|---|---|---|
| Ulnar nerve, anterior | FCU and FDS | Ulnar and median nerves | Ulnar nerve and artery |
Posterior (Thompson) Approach to the Radius
The posterior approach to the radius, also known as the Thompson approach ( Table 9-4 ), is another useful and commonly used approach to the radius ( Fig. 9-11 ). This approach is particularly useful for fractures of the proximal third of the radius because it allows enhanced exposure and visualization of the posterior interosseous nerve, which is at risk in these fractures. It also provides exposure of the tension side of the bone, which is the optimal position for plate application. This approach exploits the internervous plane between the radial and posterior interosseous nerves because the dissection is performed proximally between the extensor carpi radialis brevis (ECRB) (radial nerve) and the extensor digitorum communis (EDC) (PIN). Distally, the plane lies between the ECRB and the EPL. A linear incision is made from just distal to the lateral epicondyle of the humerus, extending distally in line with the radius, and terminating on the ulnar side of the Lister tubercle of the radius. The fascia is split in line with its fibers. The interval between the ECRB and EDC is then identified. This plane can be more easily defined distally where the muscles of the first dorsal compartment (APL and extensor pollicis brevis [EPB]) travel between the two. Dissection is carried from distal to proximal. Blunt dissection in the proximal aspect of the space reveals the underlying supinator muscle and its associated PIN. As in the anterior approach at this level, the PIN is at risk and must be protected. In contrast to the anterior approach, in the Thompson approach, the PIN is typically identified and dissected free. This is achieved with the forearm positioned in pronation. The nerve is then identified proximally or distally as it enters or exits between the deep and superficial heads of the supinator. The nerve exits approximately 1 cm proximal to the distalmost extent of the supinator. It may be necessary to detach the origins of the ECRB and ERCL so that the PIN may be visualized entering the supinator proximally. Once the nerve has been identified and protected, the forearm is supinated, and the supinator is elevated off the anterior aspect of the radius in a subperiosteal fashion, similar to that used in an anterior approach. Distally, the interval between the ECRB and EPL is exposed deep to the overlying APL and EPB. The distal radius can then be safely exposed in a subperiosteal fashion. The crossing APL and EPB can be mobilized proximally or distally to facilitate exposure of the interval and the underlying radius.
| APPROACH | MUSCULAR INTERVAL | INTERNERVOUS PLANE | DANGERS |
|---|---|---|---|
| Radius, posterior | ECRB and EDC | Radial nerve and PIN | PIN |
Posterolateral (Boyd) Approach to the Proximal Radius and Ulna
The Boyd approach ( Table 9-5 ) is unique because it allows the simultaneous exposure of the proximal radius and ulna ( Fig. 9-12 ). This distal extension of the posterolateral (Kocher) approach to the elbow is most useful for the treatment of Monteggia fractures and equivalent injuries. Proximally it exploits the interval between the anconeus (radial nerve) and the extensor carpi ulnaris (ECU) (PIN) muscles. The dissection can be extended distally along the border of the ulna, with use of the space between the ECU (PIN) and the FDP (median nerve) and the FCU (ulnar nerve) more distally. Pronation of the forearm moves the PIN anteriorly and radially, displacing it from the wound and protecting it. The supinator can then be elevated from the ulna and retracted anteriorly and radially with the PIN safely protected in its substance. Vigorous retraction of the supinator and blind placement of retractors around the radius should be avoided. At this point, the annular ligament and anterior capsule of the elbow joint are exposed. Fractures of the proximal radius, ulna, or both may be treated at this point. Open reduction of the radial head and repair or reconstruction of the annular ligament may be performed. The surgeon must be aware of the close proximity of the median nerve and brachial artery as they cross the elbow joint on the anterior surface of the joint capsule medial to the biceps tendon. The radial nerve and its superficial branch are safely anterior in the interval between the brachialis and the brachioradialis muscles.
| APPROACH | MUSCULAR INTERVAL | INTERNERVOUS PLANE | DANGERS |
|---|---|---|---|
| Radius and ulna, posterolateral | Proximal: anconeus and ECU Middle: FDS and ECU Distal: FCU and ECU | Radial nerve and PIN Median nerve and PIN Ulnar nerve and PIN | PIN, median nerve, brachial artery |
Medial Approach to the Ulna
Exposure of the ulna is typically performed through a separate incision ( Table 9-6 ). The ulna is largely subcutaneous at its ulnar border, thus facilitating its rapid and safe exposure. In addition, neither the anterior nor the posterior approaches to the radius afford adequate exposure for safe and effective fixation of fractures of the ulna. The ulna can easily be exposed in its entirety along its subcutaneous border. This approach exploits the internervous plane between the FCU (ulnar nerve) and the ECU (PIN). A longitudinal incision is made over the cutaneous border of the ulna. The plane between the FCU and ECU is confirmed, and the incision is carried directly down to the periosteum on the ulnar aspect of the bone. The ulna is then exposed in a subperiosteal fashion. Care must be taken not to inadvertently dissect on the lateral side of the FCU muscle. It is here that the ulnar nerve and artery travel in the space between the FCU and FDP muscles and are at risk of injury. These structures are also at risk during dorsal-to-volar–directed drilling and screw placement in the ulna and must be protected with careful subperiosteal retractor placement around the ulna.
| APPROACH | MUSCULAR INTERVAL | INTERNERVOUS PLANE | DANGERS |
|---|---|---|---|
| Ulna, medial | ECU and FCU | PIN and ulnar nerve | Ulnar nerve |
Technique of Forearm Compartment Release
Compartment syndrome of the forearm can be a complication in the pediatric trauma patient. High-risk injuries include floating elbows (supracondylar humerus and forearm fractures) and open forearm fractures. Pinning of both the distal humerus and distal radius and application of a loose dressing and splint is recommended for the treatment of a floating elbow to lessen the risk of a compartment syndrome. The surgeon must always be prepared to identify and deal with compartment syndromes in a safe, expeditious, and effective manner before permanent ischemic injury occurs. Clinical examination for a compartment syndrome follows classic signs of the five P s: pain, pallor, paresthesias, pulselessness, and paralysis. Pain on passive stretching of the involved compartment is considered a classic sign, but in children, it may be difficult to distinguish fracture and muscle injury pain from compartment syndrome pain. Increasing analgesic requirement, anxiety, and agitation (the three A s) precede the more dramatic signs of neuromuscular ischemia in children postoperatively. The degree of compartment swelling and tenseness is assessed with removal of constrictive dressings and casts in any suggestive case. Compartment pressure measurements are performed by standard techniques in equivocal cases. Unquestioned cases of compartment syndrome are treated emergently with surgery. The treatment of choice for an established compartment syndrome remains emergent surgical decompression of all affected muscle compartments by open fasciotomy ( Fig. 9-13 ). In the forearm, this has classically required longitudinal volar and dorsal incisions providing the exposure necessary for fascial release of the deep and superficial muscles of the anterior and posterior forearm, the mobile wad, and the carpal tunnel. More recently, the authors have used a single volar incision because this generally decompresses both volar and dorsal compartments with reduced pressures ( Fig. 9-14 ). The dorsal compartment pressure is then remeasured after volar release; if it remains elevated, a dorsal compartment release is also performed. Presently, the authors have used a vacuum-assisted device over the open wound with serial trips to the operating room until delayed primary closure can be performed. With this technique, the use of skin grafts or flaps for coverage has decreased markedly.
Reduction Techniques
Most plastic deformation and incomplete diaphyseal radial and ulnar fractures in the skeletally immature can be treated by closed reduction and cast immobilization techniques. Plastic deformation fractures with significant deformity can limit forearm rotation and have a serpentine cosmetic appearance that does not remodel if closed reduction is not performed (see Fig. 9-1 ). Correction of a plastic deformation usually requires the application of a high degree of force, often with bolster or across-knee techniques. Therefore, reduction is usually performed in the operating room under general anesthesia. This allows for pain-free testing of forearm rotation to be certain the reduction is adequate.
Greenstick or incomplete fractures are generally treated with closed reduction techniques. These fractures have predominantly rotational malalignment, although the radiographs can be misinterpreted as showing mostly malangulation. The principle of closed reduction is therefore correction of the malrotation. Most are apex volar supination deformity fractures (see Fig. 9-3 ), which are reduced first with pronation, then by three-point molding ( Fig. 9-15 ). Less often, diaphyseal incomplete fractures are apex dorsal pronation deformity fractures treated with supination reduction. These fractures are generally stable after reduction; thus cast immobilization is used.
Fixation Techniques
Closed Reduction and Percutaneous Pinning
In unstable fracture patterns, an acceptable reduction may be achieved via closed manipulation but may be difficult or impossible to maintain with traditional noninvasive forms of immobilization, such as a cast. Percutaneous smooth K- or C-wire fixation has been used as a relatively noninvasive means for providing necessary stabilization to unstable distal radial fractures. Pin fixation is generally less mechanically stable than intramedullary or plate fixation, but it has been considered an acceptable or preferred treatment option for specific fractures. The procedure is performed in the operating room under general anesthesia with use of intraoperative imaging. After anatomic reduction, pins are advanced under power with the use of fluoroscopic guidance. Utilization of an adequate incision and pin guide protection is recommended whenever tendons or neurovascular structures are at risk. Pin size, number, and configuration are determined by the fracture location and pattern. A minimum of two parallel or divergent pins is optimal for rotational control but may not always be possible. Fracture reduction, stability, and pin position are then confirmed radiographically. The pins are then bent, cut at the tip, and may be buried or left above the skin. Most often, the authors leave them out of the skin for easy removal in the office setting. Supplementation with cast immobilization is standard in children. The pins are typically removed in 3 to 4 weeks, after adequate healing has occurred.
Intramedullary Fixation
Unstable complete diaphyseal forearm fractures in the skeletally immature are often now treated with intramedullary fixation ( Fig. 9-16 ). This allows for acceptable alignment of the fracture(s) by percutaneous or minimal surgical exposure. Closed reduction of a fracture in the operating room is performed with fluoroscopic guidance. If acceptable reduction can be obtained, percutaneous fixation is performed, generally with elastic stable intramedullary nailing as introduced by Lascombes and colleagues. Small-diameter nails (1.5 to 2.5 mm) are contoured so that the apex of the bow in the nail matches the fracture site. For the radius, insertion usually involves a distal-to-proximal insertion. The distal radial physis is protected. Insertion in the metaphysis can be radial, central, or ulnar. With radial insertion, care is taken to protect the radial sensory nerve and the extensor tendons of the first and second dorsal compartments. Central insertion is performed proximal to the Lister tubercle while the thumb (EPL) and digital (EDC) extensors are protected. Ulnar-sided insertion can also be performed between the fourth and fifth dorsal compartments while the EDC and extensor digiti quinti (EDQ) are protected. For the authors, the radial rod is inserted from the radial metaphysis through a protective skin incision for the extensor tendons and radial sensory nerve. The wire is prebent into an S or C shape. A drill hole is made proximal to the physis, and insertion into the medullary canal is performed bluntly to avoid impingement or penetration of the volar or ulnar cortex. Rotation of the rod with proximal passage is performed so that the proximal aspect of the nail is in the radial neck and the apex of the nail bow is at the fracture site. Passage across the fracture site can be difficult, especially if anatomic reduction does not take place. For the ulna, most surgeons use a proximal-to-distal insertion technique ( Fig. 9-17 ). The wire can usually be passed across the proximal ulnar apophysis without consequence. This is the authors’ preferred insertion technique. It allows for a straight passage of the wire. A small incision is made over the olecranon apophysis, blunt dissection is carried down to the apophysis, and drill entry is performed into the medullary canal. Care is taken not to create a false passage through the opposite cortex. Blunt passage of the wire to and across the fracture site is performed. The other alternative is to enter the ulnar metaphysis just distal to the apophysis. This avoids the theoretical worry about growth problems but requires a bend in the pin on insertion. Rods left for a longer period of time may do better if buried under soft tissues in the metaphyseal region.
Once the pins are safely in the diaphysis, they are passed to and across the fracture sites in sequence ( Fig. 9-18 ). Most often, this can be achieved with fracture manipulation by hand, by F-tool, or by intramedullary wire adjustments. The F-tool is designed to assist with reduction while avoiding unnecessary radiation to the surgeon’s hands. However, prolonged, repetitive manipulations of the fracture site and wire passage attempts can lead to an increased risk of compartment syndrome. Therefore, if passage is difficult percutaneously, open reduction and wire passage is advocated. This may be necessary in 10% to 30% of fractures to limit complications.
Single-bone intramedullary fixation is indicated in some young children (usually ages 8 to 12 years) with unstable fractures. Most often, this is performed by intramedullary fixation of the ulna and closed reduction of the radius. However, it is important to test radial stability in the operating room with rotation and stress. If it tends to collapse with loss of the radial bow, then dual fixation is advocated.
Plate and Screw Fixation
Standard adult treatment of diaphyseal radial and ulnar fractures is indicated in skeletally mature adolescents to provide stable fixation without immobilization and to allow for early motion to prevent contracture development. Operative exposure of the radius is usually by a standard Henry approach, and exposure of the ulna is by a direct medial approach. Anatomic reduction and compression plating techniques are performed. Correction of malrotation and restoration of the radial bow is critical to successful treatment. Prophylactic forearm fasciotomies are routinely performed. Immobilization postoperatively is brief until the patient is comfortable. Protected rehabilitation is performed until full fracture healing and restoration of motion and strength are achieved. Unless the hardware is irritating, plate removal is usually not performed because of the risks of neurovascular compromise and refracture.
Pitfalls/Avoidance of Complications
Good technique, attention to detail, and appropriate and timely follow-up are the keys to minimizing complications. Inadequate reduction and loss of reduction can result from poor casting technique or acceptance of a marginal reduction or cast. Failure to recognize the rotational component of deformity can result in loss of the normal anatomic alignment and joint motion. Concomitant injuries to neurovascular structures must be recognized and dealt with appropriately. Attention to detail and good technique in cast application is necessary to avoid preventable complications such as cast-saw burns and skin breakdown. Compartment syndromes must be ruled out in all traumatic injuries to the extremity, including open fractures. A high level of suspicion and a low threshold for prophylactic compartment release can help avoid the devastating complication of Volkmann ischemic contracture. Traumatic and iatrogenic physeal injuries are unique to children, and, if unrecognized or left untreated, they can result in partial or complete growth arrest with resultant limb-length discrepancy or progressive angular deformity. Appropriate and timely antimicrobial therapy, organism culture, when indicated, and meticulous wound management limit infections.
Postoperative Care and Rehabilitation
The postoperative care after fixation of forearm fractures varies depending on several factors. Diaphyseal fractures managed by closed means are generally treated in a long arm cast with the elbow flexed to 90° and appropriate forearm rotation for a period of 4 to 6 weeks based on radiographic evidence of healing. Those fractures managed with closed reduction and pin fixations are treated in a similar manner. After intramedullary nail fixation of fractures, some surgeons allow the child to move immediately postoperatively, whereas others prefer to immobilize the child. The length of postoperative immobilization in a cast and timing of wire removal varies widely among surgeons. The issues involved in these decisions are risk of stiffness, pin problems, and possibility of refracture. Some surgeons do not cast at all, and others cast until healing. Some remove the wires when the bone is healed at 6 to 12 weeks; others leave them in place for up to a year after fracture treatment. The clear indications for removal are pin problems or infections. The risk of refracture is present for up to a year after injury; thus the timing of removal and sports participation need to take this into account for each case.
Rehabilitation is an important component of the treatment of any fracture or dislocation. However, the necessity for a formal physical or occupational therapy program varies greatly by injury type, location, chronicity, duration of immobilization, and the age of the patient. Younger children have a greater tolerance for prolonged periods of immobilization than do adolescents and young adults. Contracture secondary to cast immobilization is much less of a problem in children, often obviating the need for formal therapy. Gradual return to normal play often provides the strengthening and range of motion necessary for full recovery. Conversely, adolescents approaching skeletal maturity may behave similarly to an adult. Formal therapy may be necessary to prevent the development of a permanent elbow contracture, for example, after even a brief period of long arm casting. The need for formal therapy should be decided on case by case. Injuries of or near the hand, particularly those combined with tendon or neurovascular lacerations, more often require formal intervention by a certified hand therapist.
Special Circumstances
Monteggia Fracture–Dislocations
Monteggia fracture–dislocations can lead to dire consequences if the injury is not recognized immediately or stable reduction that prevents redisplacement is not provided. Any fracture of the forearm should be assessed for dislocation of the PRUJ and radiocapitellar joint. Appropriate anteroposterior and lateral radiographs of the wrist, forearm, and elbow are necessary for exact injury definition. Despite extensive literature about the risk of a missed Monteggia lesion and the difficulties of chronic Monteggia fracture–dislocation reconstruction, this lesion is still missed by otherwise competent orthopaedic surgeons, radiologists, and emergency and primary care physicians. Simplistically, the radius needs to be in anatomic alignment with the capitellum in all radiographic views. If this relationship cannot be adequately seen, more radiographs need to be obtained in the acute care setting.
Pediatric Monteggia lesions are classified by the direction of displacement of the radial head (i.e., anterior, posterior, or lateral) and by the type of forearm fracture. Isolated ulnar fractures constitute the majority of forearm fractures associated with radial head dislocations. These isolated ulnar fractures are categorized as plastic deformation, incomplete, and complete fractures, similar to other diaphyseal forearm fractures. Complete fractures are further classified as transverse, short oblique, long oblique, and comminuted fractures. This subclassification of ulnar fractures aids the surgeon in determining both the stability of the ulnar fracture and appropriate treatment. Other forearm fractures associated with a radial head dislocation are called Monteggia equivalents, and there are many of these. Therefore, the treating clinician needs to be aware of the possibility of an unstable or dislocated proximal radioulnar and radiocapitellar joint with any forearm fracture. All forearm fracture radiographs should be scrutinized for proximal radioulnar and radiocapitellar joint dislocations.
Successful treatment of a pediatric Monteggia fracture–dislocation depends on anatomic reduction and stabilization of the ulna. With plastic deformation and incomplete fractures, reduction and stabilization can usually be obtained by closed manipulation. The problem with plastic deformation and incomplete fractures is more often the failure to recognize the injury immediately than loss of reduction after successful reduction. With complete fractures, the complication is more often the failure to maintain reduction. Treatment by closed means for displaced transverse, short oblique, long oblique, and comminuted ulnar fractures associated with proximal radial dislocations has an increasing risk of loss of reduction by fracture type with cast immobilization. Therefore reduction and stabilization of the ulnar fracture are recommended in all these cases. Transverse and short oblique fractures are best treated with intramedullary ulnar stabilization ( Fig. 9-19 ). Long oblique and comminuted fractures of the ulna are best treated with plate-and-screw fixation after anatomic reduction.
