The Pediatric Mandible: II. Management of Traumatic Injury or Fracture

Transcription

1 CME The Pediatric Mandible: II. Management of Traumatic Injury or Fracture James M. Smartt, Jr., M.A., M.D., David W. Low, M.D., and Scott P. Bartlett, M.D. Philadelphia, Pa. Learning Objectives: After studying this article, the participant should be able to: 1. Describe the changing epidemiology of mandibular fractures in children and adolescents. 2. Discuss the appropriate use of internal fixation in the treatment of pediatric mandibular fractures. 3. Describe the difficulties posed by the deciduous dentition in the use of interdental wiring. 4. Understand reasons why techniques specific to adult fractures may not be applicable to the growing mandible. 5. Understand the etiology and epidemiology of pediatric mandibular fractures. 6. Understand the reasons for conservative (closed) versus aggressive (open) treatment of mandibular injury. Background: Fractures of the pediatric mandible are complicated by the anatomic complexity of the developing mandible, particularly by the presence of tooth buds and the eruption of deciduous and permanent teeth. Traditional methods of fracture reduction and fixation employed in adults have little applicability in the pediatric population. Methods: The authors describe the surgical techniques that have been used at their institution and those that can be used safely in the pediatric setting. Results: In most cases, conservative management is the preferred option, especially in the treatment of condylar fractures. In cases requiring surgical intervention, interdental wiring, drop wires in combination with circummandibular wires, and acrylic splints are suited well to specific phases of dental maturation. Conclusion: Open reduction and internal fixation using monocortical screws and microplates or resorbable plates and screws are acceptable techniques in the pediatric patient, but they require special safeguards. Algorithms are presented to simplify management of these complicated injuries. (Plast. Reconstr. Surg. 116: 28e, 2005.) Management of pediatric mandibular fractures is predicated upon an understanding of the developmental anatomy of the lower jaw. This information was presented in Part I of this article in the July 2005 issue of this Journal. We apply this knowledge to the development of specific age-dependent treatment protocols. EPIDEMIOLOGY, ETIOLOGY, AND DISTRIBUTION The distribution of fracture patterns at various stages of development follows logically from an understanding of mandibular anatomy. 1 While, for the majority of childhood, the mandible is small compared with the rapidly growing neurocranium, its undeveloped structure makes it vulnerable to a variety of insults. Given the protected environment provided most children during early life, it is not surprising that fractures of the mandible comprise a small percentage of facial trauma as a whole. Most series report the incidence of pediatric facial fractures as 1 to 15 percent of all facial fractures occurring in adults and children. 2 8 However, within the pediatric subpopulation, mandibular fractures are relatively prominent. The majority of large series of pediatric patients report the incidence of mandibular fractures at approximately 20 to 50 percent of all From the Division of Plastic Surgery, Department of Surgery. The University of Pennsylvania Medical Center, The Children s Hospital of Philadelphia, and the Edwin and Fannie Gray Hall Center for Human Appearance. Received for publication May 28, 2004; revised December 10, DOI: /01.prs f8 28e

2 Vol. 116, No. 2 / THE PEDIATRIC MANDIBLE childhood facial fractures Earlier studies by McCoy et al. and Hall found the incidence of mandibular fractures to be 20.7 to 40.8 percent of all pediatric facial fractures. 10,12 Later studies by Posnick et al. and Tanaka et al. largely have confirmed these earlier studies with rates of 34 and 46.9 percent, respectively. 2,13 In all studies, fractures of the mandible are more common in boys and increase in frequency until they reach 15 years of age. 2,5,13 The mechanisms of injury vary from series to series, with motor vehicle accidents, falls, and sports-related injuries contributing significantly. 5,11,13 15 In a series of 81 patients reviewed by Posnick et al., motor vehicle accidents accounted for 50 percent of all mandibular fractures, with falls (23 percent) and sports-related injuries (15 percent) accounting for the majority of the remaining fractures. 2 Siegel et al., reporting on a series from our institution, found altercations to be the most common cause of injury (35 percent), along with motor vehicle accidents (28 percent), bicycle accidents (12 percent), and falls (7 percent). 5 In most series, the proportion of injuries attributable to altercations and sports-related injuries increased with age. Strikingly, a large proportion of patients with mandibular fractures (30 to 60 percent) also experience a serious associated intra-abdominal, neurocranial or orthopedic injury attesting to the force required to effect such injuries. 9,11,16 Fracture patterns also vary with age. Multiple studies in pediatric patients have found that the incidence of condylar fractures is initially high and decreases with age. Conversely, fractures of the body and angle are initially infrequent, but increase with age. 5,8,17 Pediatric patients are more likely than adults to sustain greenstick or incomplete fractures. This is because of the relatively high elasticity of the mandible s thin cortical bone and thick surrounding layer of adipose tissue. Furthermore, because of the presence of tooth buds and developing crypts, pediatric fractures are often long and irregular in character, with the fracture generally running inferiorly and anteriorly. 12 Pediatric fractures are less likely to have multiple comminutions compared with those in adults. SPECIAL CONSIDERATIONS IN THE MANAGEMENT OF PEDIATRIC MANDIBULAR FRACTURES The anatomical complexity of the developing mandible, and concerns regarding the biocompatibility of implanted hardware, often 29e mandate the use of surgical techniques that differ markedly from those used in adults. While anatomic reduction utilizing wide exposure and rigid internal fixation has been the standard of care in adults for a long time, this method of treatment is seldom useful in children. In fact, given the pediatric skeleton s capacity for remodeling and the high incidence of minimally displaced or greenstick fractures, conservative therapy alone often is effective. 8,16,18 Clinical evidence suggests that many fractures in children remodel with little or no intervention This is especially true of the many minimally displaced greenstick fractures of the condylar necks that occur early in childhood. Consequently, a decision to undertake surgical reduction of a mandibular fracture can only be made after having assessed the age of the patient and the severity of the fracture. When surgical management is indicated, a few basic guidelines are likely to make therapy more efficacious. First, the least possible amount of the fracture site should be exposed during treatment. Recent evidence suggests that soft-tissue undermining incurred during surgery can adversely affect craniofacial growth. 22,23 These studies reaffirm Moss s original assertion regarding the importance of the functional matrix in normal growth. 24 Despite these findings, however, it has been noted that patients undergoing extensive craniofacial reconstruction for simple suture synostosis seem to attain relatively normal growth parameters. 25 While conflicting reports exist, a more conservative approach to manipulation of the periosteum and its muscular attachments seems warranted until definitive evidence is available. Finally, the pediatric dentition presents a formidable challenge to traditional surgical techniques. Arch bars used for intermaxillary fixation in adults may be of little value in the pediatric patient as the primary teeth and partially erupted secondary teeth are not a sufficiently stable foundation. In fact, the pressure exerted in intermaxillary fixation may avulse the primary teeth. The conical shape of the primary teeth, with their wide cervical margins and tapered occlusal surface, makes the placement of eyelet wires or arch bars technically challenging. Some authors have indicated that intermaxillary fixation using arch bars is safe in younger children, especially those older than 9. 16,26,27 Other studies have used mini arch

3 30e PLASTIC AND RECONSTRUCTIVE SURGERY, August 2005 bars, which exert less strain on the developing teeth. 28 In our experience, intermaxillary fixation with arch bars can only safely be used in patients older than 11 whose permanent dentition has been able to form adequate roots. 29 Before this age, one may utilize interdental wiring techniques, such as the use of eyelet wires. These techniques take advantage of individualized tooth anatomy, and, when wired to an adjacent tooth, are less prone to avulsion or tearing of the periodontal ligament. The presence of tooth buds in the pediatric mandible further complicates treatment. As discussed earlier, during the majority of childhood, tooth buds nearly approximate the inferior border of the mandible. Previous reports suggest that tooth damage and pulp obliteration are not uncommon at mandibular fracture sites. 30 Disruption of these tooth buds, or the developing teeth, with any form of internal stabilization can result in maldevelopment of permanent teeth. 31,32 Consequently, if internal fixation is used, the surgeon must be careful to avoid the developing structures. Débridement and manipulation of tooth fragments and bone chips also should be kept to a minimum. Despite these concerns, a few characteristics of the developing craniofacial skeleton make therapy somewhat easier in children than in adults. Given the high metabolic rate of most developing tissues and the increased osteogenic capacity of the periosteum, rates of healing are much higher in children. As a result, for even complex mandibular fractures, 2 to 3 weeks of immobilization may be all that is required for union. 18 This tenet holds true for nearly any form of surgical therapy that might be used. Fibrous union during the healing process is very uncommon and excellent remodeling of fracture sites is standard. This remains true even in the setting of masticatory stresses and imperfect apposition of the bone surfaces. Consequently, a much greater degree of tolerance is allowed in the alignment of bone fragments and the restoration of occlusion than in the treatment of adults. 33 NONSURGICAL TREATMENT STRATEGIES The first question that must be answered in the treatment of any child s fracture is whether or not to undertake surgical intervention. As discussed previously, the ability of the developing facial skeleton to remodel to normal proportions in the absence of treatment has been observed both clinically and experimentally. 19,20,34 Conservative management has many advantages, including a decreased immobilization time, decreased muscular atrophy, better oral hygiene, and a decreased risk of ankylosis. 35 This is especially true of condylar fractures and nondisplaced or greenstick fractures of the body and ramus in which normal occlusion is present following injury. 36,37 While the literature on condylar fractures suggests that affected children may have an increased risk of growth disturbances, no particular surgical therapy has been demonstrated to be more or less efficacious in preventing these problems. 19,38 Conservative management is further supported by clinical and experimental evidence that documents the uncomplicated healing of various mandibular fractures, including those of the condyles. 6,7,9,13,39 In our experience, conservative management of intracapsular condylar fractures, high fractures of the condylar neck, and coronoid fractures is warranted when the occlusion is normal and no barriers to movement exist. 40,41 However, in the case of fractures low in the condylar neck with significant displacement, open reduction and internal fixation should definitely be considered especially in children more than 9 years of age. Fractures of the body and angle may be treated conservatively when displacement is minimal and the patient is without functional deficits or malocclusion. After a proper radiological assessment (including Panorex films and/or axial and coronal computed tomography scans) and physical examination for normal occlusion, the imposition of a soft diet, rigorous physiotherapy, avoidance of rigorous physical contact, and symptomatic pain control may be an adequate treatment plan for a wide variety of mandibular fractures. Nonetheless, as the literature on pediatric condylar fractures attests, the effect of fractures on growth is unpredictable, making long-term follow-up essential. 38,42 SURGICAL MANAGEMENT Interdental Wiring In many cases, the use of interdental wiring is a relatively noninvasive and safe method of fracture reduction. Through this method, wires are placed around the cervical margins of stable teeth on either side of the fracture site. These wires may be attached to individual teeth or looped around a series of teeth in a bridle wire fashion. In either case, a pre-

4 Vol. 116, No. 2 / THE PEDIATRIC MANDIBLE stretched, 15-cm-long, 26-gauge, soft stainless steel wire can be used. After placement, the wire is tightened around the neck of the tooth through twisting. In the case of interdental wiring of individual teeth, a 3-cm tail should be left so as to facilitate connections with adjoining structures (Fig. 1). When bridle wires are used, shorter tails may be utilized, as they are rarely attached to other structures at the tail itself. To avoid soft-tissue trauma, the cut ends of any tails should be bent into the interdental spaces. The wires should be left in place for 2 to 3 weeks and can sometimes be removed in the office, without the need for general anesthesia. The benefits of these methods are not universal. Sufficient reduction using these techniques presupposes the presence of stable dentition, preferably of permanent teeth. As a consequence, this method is often not a viable option in children younger than 3 years of age. FIG. 1. Interdental Wiring. (Above) Bridle wires around multiple teeth. Note the placement of the wire near or at the gumline to ensure good purchase on the deciduous teeth. (Below) The use of wiring around individual teeth. These individual wires can be connected to one another to form a system of interdental stabilization. 31e Between the ages of 3 and 12, it can be applicable, but the stability of anchoring teeth must be checked in the operating room through bimanual examination. For patients between the ages of 3 and 7, the deciduous molars often provide a stable surface for immobilization. Between the ages of 8 and 13, the permanent incisors and molars often can be used. 16 This technique also can be problematic in children with stable deciduous dentitions. The shape of deciduous teeth differs markedly from their permanent counterparts. 43 The cervical margins of permanent teeth are narrower than their occlusal surface. Consequently, the teeth provide more purchase for the placement of any form of interdental wiring or intermaxillary fixation. The deciduous teeth have a tapered shape that is sometimes widest at the cervical margin. As a result, dental wires and arch bars are often difficult to apply, and may slip. When used, care must be taken to place such hardware well below the gumline. Given the large percentage of only minimally displaced or greenstick fractures of the pediatric mandible, this somewhat conservative approach is often sufficient to provide normal occlusal relations and anatomic reduction. This includes many fractures of the body, especially those in the alveolar regions. In addition, interdental wiring can be used in conjunction with any of the following techniques to gain additional stabilization of complex or oblique fractures. Occlusal Splints with Circummandibular Wires The use of occlusal splints is a versatile technique that can be used for a wide range of ages. While the composition of these splints varies, catalyst-activated acrylic has been the choice at our institution because of its ease of use. Fracture reduction is generally first performed bimanually in a closed fashion, or with a combination of interdental wiring and direct monocortical wires at the fracture site. Splints should be constructed so that the occlusal surface makes contact with the maxilla or maxillary dentition, and maintains a normal vertical dimension. After contouring and curing in the operating room with the patient under general anesthesia, the splint is applied to the lower dental arch and monomaxillary fixation achieved using two to four circummandibular wires (Fig. 2). 40 Nishioka et al. have correctly emphasized the careful placement of circummandibular wires

5 32e PLASTIC AND RECONSTRUCTIVE SURGERY, August 2005 FIG. 2. (Above) The application of occlusal splints using circummandibular wires. Note the placement of circummandibular wires both proximal and distal to the fracture itself. (Below) Axial view of the occlusal splint. Care should be taken to form the splint only after complete fracture reduction has been achieved. Furthermore, the splint should encompass both the lingual and buccal surfaces of the existing dentition. Note that the use of splints such as these is possible in nearly every stage of dental maturation and mandibular growth. so as to avoid injury to the mental nerve. 27 Wires should not be placed near the mental foramen (under the first deciduous molar, or first and second permanent premolars) or engage the fracture line (Fig. 2). In addition, care must be taken not to apply excessive force in the application of these (or any) wires as they can easily cut into the immature cortical bone. Schweinfurth and Koltai have noted the importance of thinning the posterior portion of the splint overlying the molars to prevent premature closure resulting in an open bite. 16 The acrylic splint should be left in place for 2 to 3 weeks and can usually be removed in the office, or in the operating room under light sedation. The use of splints can be particularly advantageous in a few clinical situations. In patients less than 3 years of age, with few stable dental structures, the use of splints is encouraged. In these cases, even markedly displaced fractures of the body or angle can be stabilized adequately with these techniques. Splints also provide an acceptable way to ensure normal occlusion in the face of dental instability, especially between the ages of 5 and 12. The use of splints is helpful in many situations in which interdental wiring is not acceptable. In addition, use of acrylic materials circumvents the time-consuming process of splint construction using plaster casts of the upper and lower dental arches. Splints constructed of this material can be made in any size a feature that can be of particular value when inclusion of the molars is desired. Finally, the use of monomaxillary acrylic splints obviates the use of Gunningtype splints and encourages early jaw mobilization, thus further decreasing the risk of ankylosis. Nonetheless, despite these advantages, splints also have drawbacks that make their use difficult for some practitioners. The creation of splints often increases operative time, and may not be appropriate in the presence of maxillary fractures. Splints often are unnecessary in complex fractures in which some form of internal fixation is used. In such cases, intermaxillary fixation can be provided through the use of suspensory wires attached to the piriform aperture in combination with an intermediate connecting wire. Drop Wires and Circummandibular Wires Drop wires, or a set of superiorly anchored wires attached at the midface, in combination with circummandibular wiring, offer another method of fracture reduction and fixation in children. The literature has provided various descriptions of drop wires, all using slightly different techniques. Nishioka et al. advocated the use of circummandibular, piriform rim suspension, arch bars, and a bridle wire in the treatment of isolated fractures of the mandible. 27 After the initial application of a maxillary arch bar, a bridle wire is placed to reduce the mandibular fracture at the level of the dentition and alveolar bone. A mandibular arch bar, circummandibular wires, and drop wires suspended from the lateral piriform apertures are placed and further reduction is performed. Fixation and normal occlusal relations are achieved when the maxillary and mandibular portions are connected through the use of an intermediate wire (Fig. 3). Renner et al. used a single drop wire suspended from the nasal spine in combination with two circummandibular wires in the treatment of pediatric mandibular fractures. 44 Unlike Nishioka, these authors used bimanual reduction, drop wires, and circummandibular wiring without the use

6 Vol. 116, No. 2 / THE PEDIATRIC MANDIBLE 33e FIG. 3. Intermaxillary fixation using drop wires with the application of mini arch bars, circummandibular wires, and an intermediate wire. FIG. 4. Drop wires using circummandibular wires, piriform rim suspension, and intermediate wires. (Above) The application of circummandibular wires using an awl. To insert the wires, a small stab incision is placed under the anterior surface of the inferior mandibular border. (Below) Circummandibular wires are then pulled around the inferior mandibular border and pushed superiorly through the lingual mucosal layer of the oral cavity. The buccal and lingual ends of the wires can then be tightened through gaps in the existing dentition. Intermediate wires of a lighter gauge are used to ensure that wire failures can be repaired without the need for additional invasive wiring. of arch bars. Lastly, Eppley has described the use of a large, circummandibular suture in the treatment of condylar fractures and nondisplaced fractures of the body and angle. 45 After placement of resorbable screws in each zygomatic body, a large (2-0), nonresorbable monofilament suture is passed around each side of the mandible using an awl guided through a small submandibular incision. The suture is then tied, leaving a knot high in the vestibule. With a cooperative patient, the suture can be removed in the office setting, leaving the screw to be resorbed over time. At our institution, we have used drop wires in combination with circummandibular wires in a number of patients. Ideally, we prefer to suspend the drop wires from the lateral piriform aperture (Fig. 4). In patients in whom reduction can be achieved with normal occlusion, we prefer to use the procedure without adjunctive measures such as splints or arch bars. However, the use of an interdental acrylic splint may be necessary to effect proper reduction of condylar fractures with occlusal deformities without the use of intermaxillary fixation. More specifically, fracture reduction is achieved in the operating room using bimanual manipulation. When possible, pre-installed orthodontic appliances (braces) can be used for temporary intermaxillary fixation to attain normal occlusion. After reduction, a small, submandibular incision is made and a prestretched, 25-gauge wire run on the lingual and buccal side of the mandible using an awl (Fig. 4). The wires are then tightened around the mandibular corpus, taking care to avoid damage to the mental nerve. The wires are tightened enough to provide proper reduction and fixation of the fracture, but not so much as to damage the developing bone. Moderate tension will provide adequate force to stabilize most fractures of the body, even oblique fractures in which it is important to realign both the buccal and lingual cortices. The exact number of circummandibular wires used depends on the extent of the fracture and the number of sites involved. Ideally, two wires should be place in the para-symphyseal region distal to the fracture and at least one additional wire proximal to the

7 34e PLASTIC AND RECONSTRUCTIVE SURGERY, August 2005 fracture itself. Exposure of the piriform rim is then performed through a high vestibular incision. A subperiosteal dissection is performed, with adequate release of any attachments to the anterior floor of the nose and nasal spine. A transosseous hole is then created in each piriform aperture using a 1-mm drill. A single, 26-gauge, prestretched wire is placed on each side and twisted down on an instrument with the distal portion of the wire extending just through the mucosal incision. Subsequently, a smaller, 28-gauge, intermediate wire is placed connecting the circummandibular wires (up to two within each intermediate wire) and those in the piriform aperture. Using this intermediate wire, tension is increased gradually, bringing both dental arches into proper occlusion while simultaneously providing enough force to stabilize any underlying fracture. Use of a smaller gauge connecting wire assures that if wire failure occurs it is usually in the connecting wire itself. Therefore, if replacement is necessary, it can be done without opening of the vestibular incision or placement of additional circummandibular wires. The use of drop wires offers many advantages not possible with other techniques. First, the amount of operative time is significantly decreased since the splint-making procedure is not necessary. There also is significantly less surgical exposure than that which accompanies open reduction and internal fixation. The risk to developing tooth buds is minimized, as the mandible itself is never penetrated. Also, this technique is acceptable as an adjunct for use with other methods such as splitting, interdental wiring, or the use of internal fixation. As Nishioka et al. have indicated, this method is often effective in oblique displaced fractures where the fabrication of dental splints is complicated by a poor fit. 27 Drop wires also can be effective in treating fractures of the condyles, coronoid, and body. For instance, unilateral condylar fractures with occlusal deformities and bilateral condylar fractures with a posteriorly displaced open-bite deformity are two problems that can be treated effectively using occlusal splints such as these. When used alone, the technique may not be appropriate for the treatment of angle fractures in which dentition is unavailable for proximal reduction using circummandibular wires. This technique also has many potential drawbacks. The maintenance of proper occlusal relations is contingent upon the presence of some stable dentition, preferably the deciduous molars or permanent teeth. In the case where such dentition does not exist, occlusal splinting or internal fixation is probably a better option. This criticism applies to all of the techniques reviewed above. The attachment of drop wires to different locations on the midface is also potentially problematic. Drop wires should never be placed around the zygomatic arch, as the wires will likely cut through the soft bone. 40 While Renner et al. mention the use of their nasal spine technique in children, 44 we question the ability of this structure to support the pressure exerted by intermaxillary fixation. The technique may be viable in adults, but should be applied with caution in children. Eppley s use of a nonresorbable suture should be reserved primarily for patients with nondisplaced or condylar fractures and the dental stability to maintain proper occlusion. 45 More generally, drop wires may not be efficacious in the treatment of fractures posterior to the dentition, such as fractures of the angle. Finally, the use of drop wires requires a period of immobilization and impairs oral hygiene. Open Reduction and Internal Fixation While the use of internal fixation is increasingly widespread, few studies inform the practitioner about its application in the treatment of pediatric mandibular fractures. Early discussions emphasized the importance of avoiding developing dental structures, but provided few technical details. 16,46,47 While the use of open reduction and internal fixation with and without intermaxillary fixation was indicated as a treatment modality in some publications, technical methods were not specifically addressed. 2,5,6,13,48 Wong s case description of a 5-year-old child treated with open reduction and internal fixation and arch bars was the first discussion to provide technical details. 26 Subsequently, Davison et al. were the first to undertake a larger clinical study of internal fixation of pediatric mandibular fractures. In their series of 29 pediatric patients, the authors compared more traditional methods of intermaxillary fixation (using arch bars, eyelet wires, circummandibular wires, or splints) with a free hand technique that used open bimanual reduction and internal fixation using a combination of plates, wires, and screws. The authors noted numerous advantages of using internal fixation without intermaxillary fixation, including de-

8 Vol. 116, No. 2 / THE PEDIATRIC MANDIBLE creased immobilization time, quicker resumption of a soft diet, and a quicker return to normal dental hygiene habits. They also observed similar rates of adverse events, including malocclusion, trismus, and the need for reoperation. 49 Hardt and Gottsauner also documented the use of internal fixation in a subset of patients in their study of fracture treatment. 28 Unfortunately, while offering support for the role of internal fixation without intermaxillary fixation in the treatment of children, the articles fail to provide specific technical details related to the use of internal fixation or long-term follow-up regarding efficacy and complications. At our institution, we have found that open reduction and internal fixation, when used judiciously, are indispensable in the treatment of specific subsets of mandibular fractures, including displaced fractures of the body or angle, fractures of the condylar neck with significant barriers to movement, complex fractures, and fractures in non toothbearing areas. In general terms, the use of internal fixation should follow the guidelines already discussed in this series. Open reduction should be performed cautiously, with minimal manipulation of overlying soft tissues. When possible an intraoral approach should be used to minimize the potential for visible scarring that can be significant in these cases. In addition, external appliances requiring skin incisions should be avoided whenever possible. Given the pediatric mandible s capacity to remodel properly in the face of small discrepancies in occlusion, we believe that some fractures safely can be reduced bimanually without intermaxillary fixation. Metallic internal fixation can be achieved through the use of interosseous wiring or plate fixation. Recent evidence suggests that softtissue undermining incurred during surgery can adversely affect craniofacial growth; therefore, the fracture site should only be exposed to the extent that exposure is required for treatment. 22,23,50 In patients less than 9 years of age, plates should be placed only on the mandible s inferior border using monocortical screws (Fig. 5). Drill holes always should be placed at the most inferior position and directed posteromedially, not superiorly. The use of transosseous wiring and bicortical screws should be reserved for patients older than 11 to 13, when the space between the mandible s 35e FIG. 5. Monocortical plating of the developing mandible using miniplates and screws. (Above) Note the relatively superficial movement of the monocortical screw at the inferior mandibular border. (Below) Again, placement of plate and screw fixation at the inferior mandibular border. Despite the use of these conservative fixation techniques, note the proximity of the monocortical screws and the unerupted tooth buds. inferior border and developing teeth is sufficiently large. One exception to this rule might be symphyseal fractures, in which it may be safe to use bicortical screws in patients older than 8. During the placement of screws of any type, passive adaptation of the plate to the bony surface always should be achieved. As discussed by Luhr, failure to do so can result in separation of the cortices and spurious fracture reduction with lingual gaps. 46 In addition, when fixation of the superior mandibular border is required, interdental wiring or splints should be used cautiously to avoid damage to tooth roots. While some authors have advocated the use of monocortical screws above the inferior border of tooth roots, we caution against their use because of the risk of damage to the developing teeth (Fig. 6). 49 Furthermore, to prevent plate migration and the potential for the interference with growth, interval removal of any hardware is recommended in patients less than 10 years of age. When performed properly, open reduction and internal fixation is probably a safe and versatile treatment modality. In addition to the benefits outlined by Davison et al., 49 internal

9 36e PLASTIC AND RECONSTRUCTIVE SURGERY, August 2005 fixation decreases operative time, produces stabilization in more complicated cases, and provides a means of fixation in non toothbearing areas of the mandible. Furthermore, as we have discussed elsewhere, microplates act more to FIG. 6. Compressive plate fixation at the inferior mandibular border, though not damaging to the teeth, has contributed to eruption of a permanent canine well below the alveolus. (Above) Application of monocortical plate fixation to the inferior mandibular border following fracture of the mandibular body. (Center) Panorex of a patient at 2-month followup. (Below) Patient at 1-year follow-up. stabilize fractures than to provide rigid internal fixation. As such, they act more like interosseous wires and should, in theory, be less likely to adversely affect facial growth. Nonetheless, the scale of the plates used warrants discussion. While the biomechanical forces generated by children during mastication are often of smaller magnitude than those generated by adults, we have observed clinically that children are less apt to test the repair by early chewing of hard food. 51 Hence, 1.3-mm, 1.5- mm, and 2.0-mm (midface) plates have been utilized. We have never witnessed plate bending, fracture, or displacement. This is especially true if combined with a period of intermaxillary fixation. If using plates for children, a rough guideline might include a 1.0 or 1.3 system plate in those less than 3 years of age; 1.5 system plates in patients aged 4 to 9, and 1.5 or 2.0 system plates in preadolescents and teenagers. This recommendation is experiential rather than based on experimental studies. The use of resorbable plates also is an increasingly attractive option in the treatment of a variety of conditions affecting the pediatric craniofacial skeleton, including mandibular fractures. Recent experimental studies suggest that poly-l-lactide resorbable plates may be used effectively for treatment of mandibular fractures or osteotomies in the mature craniofacial skeleton. 52,53 Studies using a variety of mandibular fracture models in animals indicate that resorbable plates and screws may be used successfully in surgical management. 54,55 The use of resorbable plates and screws has been supported further by successful reports of their clinical use in the treatment of mandibular fractures in adults. 56,57 Unfortunately, to date, the use of resorbable plates and screws has not been investigated in the treatment of pediatric mandibular fractures. However, given the decreased force exerted during mastication in children, the use of resorbable plates and screws may, in theory, be used most efficaciously in the pediatric setting. There is little evidence to suggest that poorly placed resorbable screws have any less deleterious effect on the developing dentition. It also must be remembered that, due to the biomechanics of the resorbable plates themselves, the strength of equally sized resorbable and metallic plates is not equivalent. A 1.5 -mm system resorbable plate probably provides much less stability than a 1.5-mm titanium plate. In light of this, we believe that resorbable

10 Vol. 116, No. 2 / THE PEDIATRIC MANDIBLE 37e FIG. 7. Algorithm 1. Management of body and angle fractures. CMW, circummandibular wires; IDW, interdental wiring; IMF, intermaxillary fixation; ORIF, open reduction and internal fixation. plates likely have the role of helping to maintain fracture reduction and alignment, but must be utilized with additional methods (such as wires, splints, and intermaxillary fixation). Large-scale resorbable plates (greater than 2.0 mm system) may have a role in fractures posterior to the dentition in older children, but until more experiences are published, judgment must be reserved. The possible deleterious effects of open reduction and internal fixation in children have been well documented in the literature. Experimental evidence provided by Lin et al. has demonstrated that plates and screws of the size used in managing adult fractures may, to a limited extent, adversely affect facial growth. 58 The migration of such implanted hardware also has been observed both clinically and ex-

11 38e PLASTIC AND RECONSTRUCTIVE SURGERY, August 2005 FIG. 8. Algorithm 2. Management of condylar and coronoid fractures. PRS, piriform rim suspension; CMW, circummandibular wires; IDW, interdental wiring; IMF, intermaxillary fixation; ORIF, open reduction internal fixation. perimentally. 59,60 The fate of developing teeth in fracture lines remains a controversial subject, and has great significance to surgical therapy. Kamboozia and Punnia-Moorthy have reported an increased incidence of devitalized teeth adjacent to mandibular fractures treated with plates when compared with interosseous wiring. 31 While this study is cause for concern, it should be noted that grossly displaced fractures are more likely to be treated with plates making it difficult to draw conclusions regarding the modality s actual effect on tooth vitality. While Davison et al. s study of the freehand technique provides some vindication for

12 Vol. 116, No. 2 / THE PEDIATRIC MANDIBLE the use of open reduction and internal fixation without intermaxillary fixation in pediatric patients, its conclusions should be viewed with skepticism until sufficient, long-term follow-up (19 months in their study) of facial growth, occlusion, and dental vitality is provided. 49 Given all the considerations stated above, which include age, fracture type, and location variables, as well as treatment materials, we believe it is difficult to construct an absolute treatment algorithm for these often-complicated injuries. Nevertheless, we have included here a treatment proposal realizing that flexibility in its application is the watchword, and modification may be necessary as more clinical reports detailing specific treatment modalities emerge. As a point of departure, refer to Figures 7 and 8. SUMMARY The treatment of the fractured pediatric mandible represents a therapeutic challenge to the surgeon. Treatment is complicated by the dynamic nature of the developing mandible, the presence of tooth buds, and dental instability. In the majority of cases of minimally displaced or greenstick fractures in pediatric patients, conservative management, possibly with a brief period of intermaxillary fixation, is appropriate. When surgical management is indicated, interdental wiring, occlusal splints, drop wires, and monocortical plates and screws are all legitimate treatment options. The two treatment algorithms presented here are not absolute in their applicability and mandate individualization of treatment. Furthermore, with the addition of resorbable systems to the surgeon s armamentarium and the growing literature documenting the efficacy of various treatment strategies, flexibility in the surgical management of these complicated injuries remains paramount. Scott P. Bartlett, M.D. Division of Plastic Surgery The University of Pennsylvania and The Children s Hospital of Philadelphia The Edwin and Fannie Grey Hall Center for Human Appearance Wood Building, First Floor 34th and Civic Center Boulevard Philadelphia, Pa scottbartlett@uphs.upenn.edu 39e REFERENCES 1. Smartt, J., Low, D. W., and Bartlett, S. P. The pediatric mandible. I: A primer on growth and development. In Press, Posnick, J. C., Wells, M., and Pron, G. E. Pediatric facial fractures: Evolving patterns of treatment. J. Oral Maxillofac. Surg. 51: 836; discussion 844, Rowe, N. Fractures of the jaws in children. J. Oral Surg. 27: 497, Rowe, N. Fractures of the facial skeleton in children. J. Oral Surg. 26: 505, Siegel, M. B., Wetmore, R. F., Potsic, W. P., Handler, S. D., and Tom, L. W. Mandibular fractures in the pediatric patient. Arch. Otolaryngol. Head Neck Surg. 117: 533, Norholt, S. E., Krishnan, V., Sindet-Pedersen, S., and Jensen, I. Pediatric condylar fractures: A long-term follow-up study of 55 patients. J. Oral Maxillofac. Surg. 51: 1302, Hardt, N., and Gottsauner, A. The treatment of mandibular fractures in children. J. Craniomaxillofac. Surg. 21: 214, Thoren, H., Iizuka, T., Hallikainen, D., and Lindqvist, C. Different patterns of mandibular fractures in children: An analysis of 220 fractures in 157 patients. J. Craniomaxillofac. Surg. 20: 292, Thaller, S. R., and Mabourakh, S. Pediatric mandibular fractures. Ann. Plast. Surg. 26: 511, McCoy, F. J., Chandler, R. J., and Crow, M. L. Facial fractures in children. Plast. Reconstr. Surg. 37: 209, Kaban, L. B., Mulliken, J. B., and Murray, J. E. Facial fractures in children: An analysis of 122 fractures in 109 patients. Plast. Reconstr. Surg. 59: 15, Hall, R. Injuries of the face and jaws in children. Int. J. Oral Surg. 1: 65, Tanaka, N., Uchida, N., and Suzuki, K. Maxillofacial fractures in children. J. Craniomaxillofac. Surg. 21: 289, Thomson, H. G., Farmer, A. W., and Lindsay, W. K. Condylar neck fractures of the mandible in children. Plast. Reconstr. Surg. 34: 452, Ramba, J. Fractures of facial bones in children. Int. J. Oral Surg. 14: 472, Schweinfurth, J. M., and Koltai, P. J. Pediatric mandibular fractures. Facial Plast. Surg. 14: 31, Lehman, J. A., Jr., and Saddawi, N. D. Fractures of the mandible in children J. Trauma 16: 773, Maniglia, A. J., and Kline, S. N. Maxillofacial trauma in the pediatric age group. Otolaryngol. Clin. North Am. 16: 717, Leake, D., Doykos, J., III, Habal, M. B., and Murray, J. E. Long-term follow-up of fractures of the mandibular condyle in children. Plast. Reconstr. Surg. 47: 127, Hazelrigg, C. O., and Jones, J. E. Conservative management of a fractured mandible in a ten month old child. J. Oral Med. 40: 112, Grymer, L. F., Gutierrez, C., and Stoksted, P. The importance of nasal fractures during different growth periods of the nose. J. Laryngol. Otol. 99: 741, Bardach, J., and Kelly, K. M. Does interference with mucoperiosteum and palatal bone affect craniofacial

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