DOI: 10.1148/rg.282075060
RadioGraphics 2008;28:441-461
© RSNA, 2008
Pediatric Facial Fractures: Children Are Not Just Small Adults1
Andrea Alcalá-Galiano, MD,
Ignacio J. Arribas-García, MD,
Manuel A. Martín-Pérez, MD,
Ana Romance, MD,
Juan J. Montalvo-Moreno, PhD, and
José M. Millán Juncos, PhD
1 From the Departments of Radiology (A.A.G., M.A.M.P., J.M.M.J.) and Oral and Maxillofacial Surgery (I.J.A.G., A.R., J.J.M.M.), Hospital Universitario 12 de Octubre, Av Córdoba s/n, 28041 Madrid, Spain. Presented as an education exhibit at the 2006 RSNA Annual Meeting. Received April 2, 2007; revision requested June 12 and received August 17; accepted August 27. All authors have no financial relationships to disclose.
Address correspondence to A.A.G. (e-mail: andrearoob{at}hotmail.com).
 |
Abstract
|
|---|
Radiologic imaging is essential for diagnosing pediatric facial fractures and selecting the optimal therapeutic approach. Trauma-induced maxillofacial injuries in children may affect functioning as well as esthetic appearance, and they must be diagnosed promptly and accurately and managed appropriately to avoid disturbances of future growth and development. However, these fractures may be difficult to detect on images, and they are frequently underreported. The interpretation of facial radiographs is particularly challenging, and computed tomography (CT) is necessary in many cases to achieve an accurate diagnosis. To keep the radiation dose as low as reasonably achievable, ultrasonography may be used instead of radiography for the initial imaging evaluation when the clinical suspicion of fracture is low; if evidence of fracture is found, CT then may be performed for a more detailed evaluation. Regardless of the modality used, a familiarity with the characteristic imaging features of pediatric facial fractures is necessary for accurate image interpretation. In addition, knowledge of the epidemiologic and anatomic distribution of pediatric facial fractures is helpful. Particular kinds of fracture (nondisplaced, greenstick, displaced, comminuted) tend to occur at specific anatomic sites in children, with the severity and extent of the fracture varying according to the patient’s age and the stage of skeletal development. Midfacial fractures and fractures that are severely displaced and comminuted may be accompanied by neurocranial injuries or other complications and should be evaluated at CT with multiplanar reformatting of image data.
© RSNA, 2008
|
LEARNING OBJECTIVES FOR TEST 3
|
|---|
After reading this article and taking the test, the reader will be able to:
- Describe the main differences between facial fractures in children and those in adults.
- Recognize the major facial fracture patterns seen in children at radiologic imaging.
- Identify pediatric facial fractures that have esthetic and functional implications.
|
Introduction
|
|---|
Trauma is the leading cause of morbidity and mortality among children. Although fractures of the facial skeleton are less common in children than in adults (1–8), an important part of pediatric morbidity is related to craniofacial fractures. There is a great disparity between pediatric and adult patients with regard to the available epidemiologic data, and there is little consensus in the literature about the management of pediatric facial fractures (2). Although these fractures are well described in the maxillofacial surgical literature, they have received little attention in the radiology literature.
This article describes the epidemiologic, anatomic, and radiologic characteristics of maxillofacial injuries in children. It is based on our review of the existing literature and on our findings in a series of 320 fractures in 262 patients who underwent imaging from 1992 to 2004 at our institution, one of the largest series studied to date. We begin with an overview of epidemiologic characteristics of facial fractures in children that emphasizes anatomic and developmental factors. We then describe state-of-the-art diagnostic imaging and postoperative follow-up imaging of pediatric facial fractures, giving particular attention to computed tomography (CT).
Patterns of facial injury in children differ from those in adults (1–6) because of anatomic and physiologic characteristics at different stages of facial development, as well as the extent of paranasal sinus pneumatization and phase of dentition. Therefore, radiologists must be familiar with the characteristics of facial growth and development at various ages (5). The diagnosis of facial fractures in children is difficult, and such fractures are frequently underreported (1). The interpretation of pediatric facial radiographs is especially challenging, and, in many cases, CT is necessary to confirm the diagnosis (1,4,5). However, regardless of the imaging modality used, radiologists must know where to look and what to look for.
|
Epidemiologic Features
|
|---|
The overall frequency of facial fractures in children is much lower than that in adults: Approximately 5%–15% of all facial fractures occur in children (1–6). The prevalence of pediatric facial fractures is lowest in infants and increases progressively with increasing age (1–5,8). Only 0.87%–1.0% of facial fractures occur in children younger than 5 years, whereas 1.0%–14.7% occur in patients older than 16 years (1,2). Two peaks have been observed in the frequency of such fractures: The first, at the age of 6–7 years, is associated with the beginning of school attendance (1). The second, at 12–14 years, is related to increased physical activity and participation in sports during puberty and adolescence (1,3).
In our case series, the age distribution was as follows: 56 children (21.4%) were younger than 5 years, 138 (52.7%) ranged in age from 6 to 12 years, and 68 (25.9%) were older than 13 years. Children near the age of 16 years were probably excluded from our series because they are usually attended in the adult division.
There is a marked preponderance of boys in the worldwide pediatric population affected by facial fractures, with the male-to-female ratio ranging from 1.1:1 to 8.5:1, depending on the series (1–4). The preponderance of boys is attributed mainly to the fact that their physical activity is more intense and more hazardous than that of girls (1,2,4,5,8). The statistics from our patient population are comparable to those reported in the literature: 66.5% of facial fractures occurred in boys and only 33.5% in girls.
|
Causes of Facial Fracture
|
|---|
The main causes of pediatric facial fracture vary, depending on the data source. The statistics in our series are well within the ranges reported in the literature: Motor vehicle accident was the most common cause; it accounted for 36.4% of fractures in our case series (5%–80.2%, in the literature). Sports-related injury was the next most common cause, at 26.2% (4.4%–42%). It was followed by accidental causes, such as a fall, at 23.1% (7.8%–48%); violence, at 9.3% (3.7%–61.1%); and other causes, at 6.2% (9.3%) (1–4,8). Some authors group bicycle accidents in a broader category with other accidental causes of fracture, as we did for the present analysis. However, because a large percentage of facial fractures are attributable to bicycle accidents (7.4%–48%), such accidents have been considered as an independent category by other authors.
Causes of fracture are closely linked with age-related levels of activity (1,3,5). Young children who are supervised constantly and have a protected environment usually sustain fractures from low-velocity forces such as those encountered in falls, whereas older children more commonly have injuries due to high-velocity forces such as those encountered in motor vehicle accidents or sports activities. The frequency of severe fractures increases with age, as does the frequency of surgically treated fractures.
When assessing fractures in children, the radiologist should always bear in mind the possibility of child abuse. Half of all injuries in battered children (especially in infants and children younger than 5 years) are injuries to the head and neck (2,5). Facial fractures are seen in 2.3% of abused children (1). Multiple physical injuries to the head and neck, missing or broken teeth, multiple fractures of different ages, and fracture malunion or nonunion should arouse suspicion about child abuse (2).
|
Associated Injuries
|
|---|
Pediatric facial fractures generally result from severe trauma, and the frequency of associated injuries therefore is high (25%–75% in our series and 10%–88% in the previously published literature, depending on the type of facial fracture) (1–6,8). There is a positive association between the complexity of the fracture and the likelihood of other injury (1,5). Midfacial or mandibular fractures, in particular, entail a higher risk of associated injury, since these fracture patterns imply high-energy mechanisms (1,8). The presence of an associated injury may be expected if there is a fracture of resistant or protected bones, since such fractures imply a high-force impact (5). The most common associated injuries in cases of midfacial and mandibular fractures are neurocranial injuries (1,3,5,9). It is important to consider the possibility of a central nervous system injury in such cases (2,5).
|
Anatomic Distribution of Facial Fractures
|
|---|
Fracture patterns in children are similar to those in adults, but the percentages of fractures found at each anatomic site are different in the pediatric age group (8). In our series of pediatric patients, nasal fractures were by far the most frequent (58.6%), followed by mandibular fractures (21.5%). Orbital (9.5%), frontal skull (5.1%), and midfacial (3.8%) fractures were next in frequency, and complex fractures (naso-orbito-ethmoidal, Le Fort) were the least common (1.5%) (Fig 1). Alveolar and dental fractures were not included in our series, since they are usually managed in the outpatient setting (1,2). Those kinds of fractures are very common in children and, together with nasal fractures, they are the ones most frequently considered in the pediatric literature (1,2,4,5,8). They are most prevalent in children aged 8–9 years (2). Because many nasal fractures are treated in the office setting (6), the frequency of their occurrence is probably underestimated.
View larger version (40K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1. Drawing of the pediatric skull shows the anatomic locations and frequency of occurrence of common fractures in our case series. Nasal fractures are the most frequent, followed by mandibular fractures, which are the most commonly found facial fracture in hospitalized patients. Orbital, frontal skull, and midfacial fractures occur with moderate frequency. Complex fractures, such as naso-orbito-ethmoidal (NOE) and Le Fort fractures, are the least frequently occurring facial fractures in children.
|
|
The results of our analysis are comparable to those previously reported in the literature. 
According to the available sources, nasal fractures are the most common, around 50% of the total, followed by mandibular fractures (15%–48.8%). Mandibular fractures are most often diagnosed in the hospital setting (1,2,8,10). The reported frequency of orbital fractures ranges from 3% to 20%, and that of midfacial fractures, from 8% to 54%. The frequency of zygomatic arch fractures is 23.6%; that of alveolar fractures, 19.4%; and that of Le Fort fractures, 4.6%. Hard palate fractures are the least common, at 0.5% (1–3,5,8,9).
|
Effects of Age and Development
|
|---|
Pediatric facial trauma has distinctive imaging characteristics because of anatomic and physiologic differences between the pediatric and the adult facial skeleton (5). The main differences may be observed in (a) the extent of facial growth and development (skull-to-face ratio), (b) the extent of paranasal sinus development, (c) the phase of dentition, and (d) the structure of bone and soft tissues. As a result of these differences, facial fractures occur less frequently and are more often minimally displaced or nondisplaced in children than in adults (1–8).
In very young children, the frontal protrusion of the cranium and the relative retrusion of the face generate a greater risk of skull fracture than of facial fracture from blunt frontal trauma; the skull absorbs the full force of the initial impact, thus "protecting" the face (1,3,5,6). With increasing age and physiologic development, the face undergoes a downward and forward projection, with the midface and mandible becoming more prominent. The skull-to-face ratio is 8:1 at birth and 2.5:1 in adulthood: The cranium quadruples in size from birth to adulthood, while the face undergoes a 12-fold increase (3,5,6) (Fig 2). The frequency of pediatric facial fractures thus increases with age, while that of cranial lesions decreases (1,3,5). Among children younger than 5 years, midfacial and mandibular fractures are less common than cranial, frontal, and orbital fractures (1,6). Fractures in children younger than 3 years usually are isolated, nondisplaced, and caused by low-energy forces (1). In contrast, older children sustain a greater number of mandibular and midfacial fractures.
View larger version (86K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2. Comparison of the facial anatomy of a child and an adult. Diagrams (top row) and radiographs (bottom row) show the characteristic frontward protrusion of the child’s sinciput (left column) and the relative retrusion of the adult’s sinciput with greater prominence of the midface and mandible (right column). The skull-to-face ratio decreases almost four times with normal growth and development between birth and adulthood.
|
|
Pneumatization of the paranasal sinuses begins in the ethmoid sinus and continues sequentially in the maxillary sinuses, the sphenoid sinuses, and, finally, the frontal sinuses (2,5,10). The sinuses reach their full size only after puberty and the complete emergence of all the teeth (2). The maxillary and frontal sinuses (Fig 3) play an important role in pediatric facial fracture patterns, with a positive correlation existing between the frequency of midfacial fractures and the stage of development and pneumatization of the paranasal sinuses (3,5). Lack of pneumatization is associated with increased stability (1,3); however, with greater pneumatization, the sinuses may absorb more of the impact and provide a cushioning effect (5).
View larger version (41K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3. Diagram shows the development of the frontal and maxillary sinuses according to age in years. Increasing development of the paranasal sinuses is positively correlated with the prevalence of midfacial fractures in children. The sinuses reach their full size after puberty.
|
|
With regard to dentition, three phases have been described: (a) a deciduous phase, around the age of 2 years, (b) a mixed phase, from 6 to 12 years, and (c) a permanent or definitive phase, around the age of 13 years (2,5). Incomplete dentition provides additional strength to the maxilla and mandible, because the presence of tooth buds within the jaw increases the stability and elasticity of the bone (1,3,5). The phase of dentition may limit the options for treating fractures of the jaw.
Children have a higher resistance to facial fractures and a greater susceptibility to greenstick fractures than adults do, in part because of the structure of bone in the pediatric facial skeleton. The abundance of cartilage and cancellous bone, low mineralization, and underdeveloped cortex, along with the more flexible suture lines and indistinct corticomedullary junction, confer greater elasticity and flexibility on the pediatric facial skeleton (1,3,5,6). The thick layer of adipose tissue that overlies much of the pediatric facial skeleton, and the fat pads that surround the upper and lower jaws, also help protect these bones (1,3).
|
Diagnostic Imaging Methods
|
|---|
Radiography provides limited diagnostic information about pediatric facial fractures—particularly midfacial and condylar fractures, which may be easily overlooked on radiographs (1–3,6). Fractures may be obscured by anatomic features such as incompletely ossified areas with underdeveloped cortical bone or abundant cartilage and soft tissues. In addition, numerous tooth buds may mask anatomic landmarks in both the maxilla and the mandible. The paranasal sinuses often are small and minimally pneumatized (1–6). Greenstick fractures, which occur with a high frequency in children, are difficult to detect on radiographs because they are not displaced and do not disrupt both cortical tables. In addition, children are often uncooperative, and patient positioning for the various necessary radiographic projections often requires more cooperation than is possible (5,6). Although these factors generally hinder the radiographic depiction of fractures, many specialized radiographic techniques have been devised to allow depiction of the entire facial skeleton (eg, Waters, Caldwell, and Towne views; submentovertex and lateral projections; and panoramic radiographs [orthopantographs]). Panoramic radiographs provide accurate depiction of fractures in the body of the mandible and are essential for surgical planning. Panoramic radiography therefore is performed for the initial diagnostic evaluation when a mandibular fracture is believed present, and supplemental radiographic views are acquired if necessary (1,5,6).
Multi–detector row CT, where it is available, has largely replaced radiography as the modality of choice for the imaging of pediatric patients with maxillofacial trauma, especially for evaluating fractures of the middle and upper regions of the face (5). CT greatly increases diagnostic accuracy and may reveal previously unsuspected fractures (1,3,4,11). CT with multiplanar reformatting and three-dimensional (3D) volume rendering of image data allows accurate diagnosis and provides precise depiction of anatomic details to guide surgeons in achieving the accurate reduction of fractures, particularly those of the midface (1,3–5). Coronal reformatted images provide important information about midfacial and complex fractures, are useful for depicting changes in facial volume and width, and are essential for assessing orbital roof and floor fractures (6). A detailed assessment of pediatric mandibular fractures, especially those involving the temporomandibular joint or the condyle, more frequently requires the multiplanar reformatting of image data than does the assessment of similar fractures in adults (1,5,6,9).
One of the main disadvantages of CT is the high radiation dose to which the eye may be exposed, with the resultant increased potential risk for the development of cataracts. However, low-dose scanning protocols may be used (12–17), particularly if there is little suspicion of a fracture or if low-energy trauma has been sustained. The image acquisition parameters may be modified to reduce the effective dose, but this generally results in increased image noise (14,16), although some authors have claimed the achievement of a 40% dose reduction without any loss of diagnostic image quality (17). The use of dose modulation with maximum amperage of 160 mA and with a reduction of peak voltage to 120 kVp results in a reduction of the effective radiation dose, but the protocol has to be adapted to each individual patient. Some authors (16) have described the acquisition of images with adequate diagnostic quality by using amperage as low as 40 mA and peak voltage of 80 kVp. In general, the tube voltage and current are the parameters that most affect dose reduction; increasing the section thickness, the pitch factor, or the detector configuration does not lead to a significant reduction in the radiation dose (15–17). Multi–detector row CT incurs greater radiation exposure than does helical CT (15).
In general, although the interpretation of radiographs of the midface in children is particularly difficult, radiography is useful for the initial evaluation of low-energy trauma. If high-energy trauma has occurred or if the findings at clinical examination are suggestive of a complex fracture with possible neurocranial injuries, CT should be performed instead of radiography for optimal diagnostic assessment.
Ultrasonography (US) has been described as a useful method for the initial detection of displaced fractures in the midfacial region (the orbit, zygomatic arch, and nasal bone) and screening for dubious fractures. High-frequency US with either a linear- or a curved-array transducer (the latter type being used to assess the orbital walls) may be performed as an alternative to radiography for the initial diagnostic work-up (12,13,18). High-frequency US is safe, inexpensive, and accurate and may be used in place of radiography before CT, as an adjunct technique with physical examination, or as a substitute for follow-up radiography (12,19). It has been used for immediate postoperative evaluation and to assess the subsequent remodeling of bone (12,13). US can help identify small bone fragments in cases of comminuted fracture, as well as the typical M-shaped reflections in depressed or displaced fractures (13). The use of US is less widely established for the evaluation of fractures in the maxillofacial area than in other parts of the anatomy, and there are not enough data available currently to support such use (12,13). Some authors have stated that US has a positive predictive value similar to that of CT and may be used as an alternative to CT (12,18). In the detection of fractures of the zygomatico-orbital complex at US, satisfactory sensitivity and specificity have been reported (12). Other authors have asserted that US is less sensitive than CT, that it results in too great a number of false-negative results (19), and that it is insufficient for the diagnosis of nondisplaced fractures and fractures of the mandibular condyle and mandibular ramus; radiography is better for such purposes (13). Emphysema greatly limits the diagnostic accuracy of US (12,13) because the condition causes a ring-down artifact. Soft-tissue swelling and edema also decrease the sensitivity of this technique (12). Moreover, US should not be performed on open wounds or painful injuries. Since there is a consensus about the need to decrease radiation exposure by decreasing the total number of diagnostic radiographic studies, CT should be performed (without previous radiography) if US images depict a displaced fracture (13).
Magnetic resonance (MR) imaging provides reliable and adequate information about soft tissues but not bone fractures (12,13). It is also time consuming and may require patient sedation. For these reasons, it is not included in the standard diagnostic work-up for facial trauma in children.
|
Imaging Appearances
|
|---|
Nasal Fractures
Apart from alveolar fractures, nasal fractures are the most common type of pediatric facial fracture. Nasal fractures account for approximately half of all pediatric facial fractures (1,2,5) (Fig 4). The nasal bones are the least resistant and most prominent bones in the facial skeleton (1), and this fact helps explain why they are so often fractured although the nasal cartilage is compliant (6). When a nasal fracture is suspected, a clinical examination and lateral radiographs should be sufficient for the initial work-up. Many nasal fractures are diagnosed and treated in an outpatient setting. However, nasal fractures in children frequently are masked by edema, and the standard radiographic assessment may be inadequate (2). Nasal fractures also may be obscured by cartilaginous nasal structures (6). Even at CT nasal fractures are frequently overlooked; the radiologist must remember to examine the nasal bones carefully, checking for depressed fragments, lateral deviation of the nose, and evidence of septal disruption. Septal fracture is common (5,6), and in such cases a septal hematoma, although rare, must be ruled out at CT. Septal hematomas generally are detected during the initial clinical examination and immediately drained to prevent septal avascular necrosis, superinfection, and later growth disturbances (2,5,20–22). In cases of complex fractures that impede examination or in uncooperative patients, a septal hematoma may be detected incidentally. On CT images, a septal hematoma appears as a subperiosteal hyperattenuating fluid collection that causes a thickening or bulging of the nasal septum; however, this feature may be difficult to distinguish from intranasal surgical packing material (2,5).
Mandibular Fractures
Fractures of the jawbone are most frequently found in hospitalized children (1). This type of fracture is more frequent in children than in adults (50% vs 30%) because of the prominent vascularization of the condyle in children and the relatively large amount of medullary bone surrounded by a thin rim of cortical bone (1,6). Children tend to have only one fracture site, whereas adults usually have more than one site of fracture (6). In our series, the most frequent mandibular fracture sites were condylar and subcondylar (43.5%) (Figs 5–7). Next in order of frequency were sites in the parasymphysis (24.2%), angle (19.3%), symphysis (3.2%), and various other parts of the mandible (9.7%). Our results are comparable to those reported in the literature, in which condylar fractures are by far the most frequent (14.5%–60%), followed by fractures of the body (5.6%–44%) (Fig 8), symphysis (1.8%–40.4%), parasymphysis (23.9%–33.7%), angle (3%–27%) (Fig 9), ramus (0.75%–10%), and coronoid process (0.1%–19%) (1–3,6).
View larger version (135K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5a. Intracapsular condylar fracture in a 6-year-old girl involved in a motor vehicle accident. (a) Lateral facial radiograph shows a fracture line (arrowhead) in the left condylar head. (b) Axial unenhanced CT image provides better delineation of the intracapsular fracture of the left condyle (arrow), which is dislocated from the temporomandibular joint fossa. Note the small bone fragments posterior to the condyle. No additional mandibular fractures were found.
|
|
View larger version (108K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5b. Intracapsular condylar fracture in a 6-year-old girl involved in a motor vehicle accident. (a) Lateral facial radiograph shows a fracture line (arrowhead) in the left condylar head. (b) Axial unenhanced CT image provides better delineation of the intracapsular fracture of the left condyle (arrow), which is dislocated from the temporomandibular joint fossa. Note the small bone fragments posterior to the condyle. No additional mandibular fractures were found.
|
|
View larger version (84K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6a. Intracapsular crush fracture of the left condylar head in a 13-year-old boy after a fall from a bicycle. (a) Panoramic radiograph shows a slight inferior displacement of the left condyle (arrowhead) in comparison with the right condyle, although the contours of the condyles are partially obscured. (b) Axial unenhanced CT image clearly shows a comminuted intracapsular fracture of the left condylar head (arrowhead), which is dislocated from the temporomandibular joint fossa. No other mandibular fractures were found.
|
|
View larger version (137K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6b. Intracapsular crush fracture of the left condylar head in a 13-year-old boy after a fall from a bicycle. (a) Panoramic radiograph shows a slight inferior displacement of the left condyle (arrowhead) in comparison with the right condyle, although the contours of the condyles are partially obscured. (b) Axial unenhanced CT image clearly shows a comminuted intracapsular fracture of the left condylar head (arrowhead), which is dislocated from the temporomandibular joint fossa. No other mandibular fractures were found.
|
|
View larger version (87K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7a. Subcondylar fractures. (a) Panoramic radiograph shows an isolated displaced left subcondylar fracture (arrow) in a 13-year-old boy after a fall from a bicycle. (b) Axial CT image shows a fracture (arrowhead) in the lower right subcondylar region in a 9-year-old girl who was run over by a vehicle. Note the tooth buds embedded in the posterior walls of the maxillary sinuses and the opacification of the right maxillary sinus.
|
|
View larger version (107K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7b. Subcondylar fractures. (a) Panoramic radiograph shows an isolated displaced left subcondylar fracture (arrow) in a 13-year-old boy after a fall from a bicycle. (b) Axial CT image shows a fracture (arrowhead) in the lower right subcondylar region in a 9-year-old girl who was run over by a vehicle. Note the tooth buds embedded in the posterior walls of the maxillary sinuses and the opacification of the right maxillary sinus.
|
|
View larger version (118K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8a. Fracture of the horizontal ramus of the right mandibular body in a 12-year-old boy after a fall from a bicycle. (a) Lateral projection radiograph shows a nondisplaced fracture in the right horizontal ramus (arrowheads). (b) Axial CT image distinctly shows the same fracture (arrowhead). No other fractures were present. (c) Volume-rendered 3D CT image depicts the fracture (arrow) in a more precise anatomic orientation.
|
|
View larger version (149K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8b. Fracture of the horizontal ramus of the right mandibular body in a 12-year-old boy after a fall from a bicycle. (a) Lateral projection radiograph shows a nondisplaced fracture in the right horizontal ramus (arrowheads). (b) Axial CT image distinctly shows the same fracture (arrowhead). No other fractures were present. (c) Volume-rendered 3D CT image depicts the fracture (arrow) in a more precise anatomic orientation.
|
|
View larger version (138K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8c. Fracture of the horizontal ramus of the right mandibular body in a 12-year-old boy after a fall from a bicycle. (a) Lateral projection radiograph shows a nondisplaced fracture in the right horizontal ramus (arrowheads). (b) Axial CT image distinctly shows the same fracture (arrowhead). No other fractures were present. (c) Volume-rendered 3D CT image depicts the fracture (arrow) in a more precise anatomic orientation.
|
|
View larger version (91K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9a. Fractures of the mandibular angle and parasymphysis in a 12-year-old boy involved in a motor vehicle accident. (a) Anteroposterior skull radiograph shows a depressed fracture in the right frontotemporal region (arrowheads), a displaced fracture of the left mandibular angle (arrow), and an intracranial pressure monitor bolt in the right frontal region. (b) Axial CT image more clearly depicts the left mandibular angle fracture (arrow) and shows a nondisplaced fracture of the right parasymphysis (arrowhead).
|
|
View larger version (96K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9b. Fractures of the mandibular angle and parasymphysis in a 12-year-old boy involved in a motor vehicle accident. (a) Anteroposterior skull radiograph shows a depressed fracture in the right frontotemporal region (arrowheads), a displaced fracture of the left mandibular angle (arrow), and an intracranial pressure monitor bolt in the right frontal region. (b) Axial CT image more clearly depicts the left mandibular angle fracture (arrow) and shows a nondisplaced fracture of the right parasymphysis (arrowhead).
|
|
Condylar fractures are often bilateral (20%) (1). When they occur in children younger than 6 years, the fracture line is typically intracapsular; in older children, it is primarily extracapsular (involving the condylar neck) (1). There are three main types of condylar fracture: (a) intracapsular crush fracture of the condylar head (Figs 5, 6), (b) high condylar fracture, through the neck above the sigmoid notch, and (c) subcondylar fracture associated with a greenstick fracture of the mandibular neck. The third type is the most common (Fig 7) (6).
For the evaluation of a suspected mandibular fracture, panoramic radiography is performed with the acquisition of supplemental views (posterior-anterior, lateral oblique, and occlusal) (1). For the initial diagnostic assessment of a condylar fracture, panoramic radiographs may be acquired in addition to temporomandibular joint views, since the joint is usually poorly depicted because of distortion artifact on the latter; or if a condylar fracture or fracture of the angle is suspected, a Towne view may be obtained (5,6). CT is useful because it provides a detailed cross-sectional depiction of mandibular fractures, particularly those involving the temporomandibular joint or the condyle; it usually is used to determine whether the condyle is dislocated from the temporomandibular joint fossa, to evaluate the degree of displacement, and to locate fragments (1,5,6,9).
When reporting a mandibular fracture, the degree of comminution and displacement of fragments should be described. Mandibular fractures other than condylar and subcondylar fractures are usually surgically treated although they are typically nondisplaced. In dislocated condylar and subcondylar fractures, the exact position of the condyle in relation to the temporomandibular joint fossa must be described, and the presence of any intracapsular fracture lines must be reported.
Fractures of Frontal Bone and Orbital Roof
Fractures of the frontal bone in young children are common because of the prominence of the forehead, which overhangs the face (1,3,5,6). Because pneumatization of the frontal sinus does not occur until the age of 5–8 years, frontal fractures tend to extend superiorly into the skull or across the orbital roof (5). A radiologic finding of fracture in the frontal bone should lead to consideration of the possibility of intracranial lesions and to consultation with a neurosurgeon (2). Fractures of the cranial vault are uncommon, but the frontal bone (Fig 10) is the most frequently fractured. Posterior wall fractures of the frontal sinus are associated with leakage of cerebrospinal fluid (5).
View larger version (123K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10a. Frontal bone fracture in a 13-year-old boy after a fall from a bicycle. (a) Anteroposterior skull radiograph shows a parasagittal fracture line (arrowheads) in the left frontal bone. (b) Axial CT image shows a nondisplaced fracture through the left frontal bone (arrowhead) and a lack of pneumatization of the frontal sinuses. (c) Axial CT image shows the extension of the fracture line (arrowhead) to the root of the nose and the anterior ethmoid cells. Because of the high risk of brain injury associated with a fracture of this type and extent, a neurosurgeon should be consulted.
|
|
View larger version (96K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10b. Frontal bone fracture in a 13-year-old boy after a fall from a bicycle. (a) Anteroposterior skull radiograph shows a parasagittal fracture line (arrowheads) in the left frontal bone. (b) Axial CT image shows a nondisplaced fracture through the left frontal bone (arrowhead) and a lack of pneumatization of the frontal sinuses. (c) Axial CT image shows the extension of the fracture line (arrowhead) to the root of the nose and the anterior ethmoid cells. Because of the high risk of brain injury associated with a fracture of this type and extent, a neurosurgeon should be consulted.
|
|
View larger version (104K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10c. Frontal bone fracture in a 13-year-old boy after a fall from a bicycle. (a) Anteroposterior skull radiograph shows a parasagittal fracture line (arrowheads) in the left frontal bone. (b) Axial CT image shows a nondisplaced fracture through the left frontal bone (arrowhead) and a lack of pneumatization of the frontal sinuses. (c) Axial CT image shows the extension of the fracture line (arrowhead) to the root of the nose and the anterior ethmoid cells. Because of the high risk of brain injury associated with a fracture of this type and extent, a neurosurgeon should be consulted.
|
|
In children younger than 7 years, in whom the frontal sinus is not yet pneumatized (1,5,6,16), frontal fractures affect the orbital roof almost exclusively, but they also may extend to the frontal bone (2). The lack of a cushioning effect of the bone (2). The lack of a cushioning effect of the sinus causes direct transmission of the impact sustained on the frontal prominence or orbital rim to the orbital roof (5,6). Orbital roof fractures are considered skull fractures, and they are frequently associated with neurocranial injury (Fig 11) (1,5,6). These fractures are most clearly depicted on coronal reformatted CT images (5). The radiologist must evaluate the appearance of the extraocular muscles—in this case, the superior rectus muscle and the superior oblique muscle—for signs of muscle impingement or entrapment, such as thickening or displacement. Exophthalmos also may occur because of the decrease in orbital volume (5,23).
View larger version (125K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11a. Orbital roof fracture in a 12-year-old girl after a fall. (a) Radiograph (Waters view) shows discontinuity of the right orbital roof, with a small displaced bone fragment (arrowhead). (b) Coronal reformatted CT image provides superior depiction of the extent of the fracture and the location of the displaced fragment (arrowhead). Emphysema also is visible in the right orbit.
|
|
View larger version (136K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11b. Orbital roof fracture in a 12-year-old girl after a fall. (a) Radiograph (Waters view) shows discontinuity of the right orbital roof, with a small displaced bone fragment (arrowhead). (b) Coronal reformatted CT image provides superior depiction of the extent of the fracture and the location of the displaced fragment (arrowhead). Emphysema also is visible in the right orbit.
|
|
Fractures of Orbital Floor and Rim
Orbital floor and orbital rim fractures are rare in young children, in whom the force of blunt trauma on frontal bone is normally transmitted to the orbital roof because of incomplete pneumatization of the frontal sinus wall and relative underdevelopment of the orbital floor and rim (6). The frequency of orbital floor fractures increases with the increasing pneumatization of the maxillary sinus (1,2,5,6,23). As the frontal sinus develops, it absorbs more of the force of impact and transmits less of it to the orbital roof; thus, roof fractures become less common (6). After the age of 7 years, orbital fractures mainly affect the medial and lateral walls and the floor (1,2). As the paranasal sinuses develop and the face undergoes a downward projection, the frequency of such fractures increases (6).
A common fracture in children at this age is the "blowout" fracture of the orbital floor (Fig 12). The usual mechanism is a direct blow to the eye, with the force of the impact being transmitted downward through the orbital soft tissues to the thin orbital floor. The floor is usually the site of the least resistant bone, and floor fractures typically project downward into the maxillary sinus. Common clinical signs of such fracture are enophthalmos (due to increased orbital volume) and diplopia (especially in the presence of ocular supraversion) (5,23). Approximately 24% of such fractures are associated with ocular injury.
View larger version (129K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12a. Blowout fracture in a 14-year-old boy after a blow to the left eye. (a) Radiograph (Waters view) shows a slightly depressed fragment of the left orbital floor (arrow) and an air-fluid level in the left maxillary sinus (arrowhead). (b) Coronal reformatted CT image obtained with bone window settings shows the depressed bone fragment (arrow), a minimally displaced fracture of the lamina papyracea (arrowhead), and obliteration of the ethmoid cells. (c) Coronal reformatted CT image obtained with soft-tissue window settings shows a thickened and rounded appearance of the inferior rectus muscle (*), a finding indicative of muscle impingement, and depicts a hemorrhage in the left maxillary sinus (arrowhead).
|
|
View larger version (130K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12b. Blowout fracture in a 14-year-old boy after a blow to the left eye. (a) Radiograph (Waters view) shows a slightly depressed fragment of the left orbital floor (arrow) and an air-fluid level in the left maxillary sinus (arrowhead). (b) Coronal reformatted CT image obtained with bone window settings shows the depressed bone fragment (arrow), a minimally displaced fracture of the lamina papyracea (arrowhead), and obliteration of the ethmoid cells. (c) Coronal reformatted CT image obtained with soft-tissue window settings shows a thickened and rounded appearance of the inferior rectus muscle (*), a finding indicative of muscle impingement, and depicts a hemorrhage in the left maxillary sinus (arrowhead).
|
|
View larger version (132K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12c. Blowout fracture in a 14-year-old boy after a blow to the left eye. (a) Radiograph (Waters view) shows a slightly depressed fragment of the left orbital floor (arrow) and an air-fluid level in the left maxillary sinus (arrowhead). (b) Coronal reformatted CT image obtained with bone window settings shows the depressed bone fragment (arrow), a minimally displaced fracture of the lamina papyracea (arrowhead), and obliteration of the ethmoid cells. (c) Coronal reformatted CT image obtained with soft-tissue window settings shows a thickened and rounded appearance of the inferior rectus muscle (*), a finding indicative of muscle impingement, and depicts a hemorrhage in the left maxillary sinus (arrowhead).
|
|
The most characteristic orbital blowout fracture in children, although it is relatively uncommon among pediatric facial fractures, is the so-called trapdoor fracture (16,17). This is a green-stick fracture in which a bone fragment protrudes into the sinus while remaining stably attached by a "hinge" of mucoperiosteum to the intact part of the orbital floor, usually on the ethmoidal side. If the displaced fragment springs back into its original position, prolapsed orbital tissues may be entrapped on the maxillary sinus side of the orbital floor. Such features may be easily overlooked at imaging. A prolapsed inferior rectus muscle, for example, may be easily missed on standard radiographic views (23,24). However, on Waters views, a soft-tissue mass (the herniated periorbital tissues) may be visible on the superior margin of the maxillary sinus. CT images, especially coronal reformatted images, depict trapdoor fractures and associated soft-tissue masses more clearly than radiographs (5). In a trapdoor fracture that has spontaneously reduced, the only abnormal imaging feature may be periorbital fat or rectus inferior muscle entrapped beneath the floor of the orbit (23,24). This type of fracture requires urgent surgical management to avoid eye motility sequelae (23).
In cases of frontal and orbital fractures, the radiologist should determine the extent and location of the fracture and should be alert for signs of eye or extraocular muscle involvement, such as periorbital fat herniation (Fig 13), extraocular muscle entrapment, exophthalmos, enophthalmos, and retro-ocular hematoma. The globe should be examined carefully. A finding of intraorbital gas usually is indicative of a fracture in the paranasal sinus walls, although this finding in itself has no clinical importance. Opacification of, and air-fluid levels in, the paranasal sinuses may be additional signs of fracture. The sinus drainage pathways, nasolacrimal and nasofrontal ducts, and infraorbital nerve canal should be inspected thoroughly to rule out injury. Fractures affecting these structures may cause subsequent stenosis of the nasolacrimal and nasofrontal ducts or may be indicative of a lesion of the infraorbital nerve (23).
View larger version (105K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13a. Medium-energy injuries to the left orbital floor and zygomatic complex in a 10-year-old girl after a motor vehicle accident. (a) Axial CT image at the level of the midface shows an impacted left zygomatic complex fracture that involves the zygomatic process of the maxilla and a secondary fracture of the anterior and lateral wall of the maxillary sinus. Note the accumulation of blood in the sinus and the inflammation of periorbital soft tissue. (b) Axial CT image shows a fracture of the lateral wall of the left orbit with several displaced fragments (arrows). (c) Coronal reformatted CT image obtained with bone window settings shows fractures of the frontal (black arrowhead) and maxillary (white arrow) zygomatic processes and a fracture of the orbital floor with a displaced fragment (white arrowhead) and herniation of orbital contents into the maxillary sinus (black arrow). A nondisplaced fracture of the zygomatic arch also was present (not shown). (d) Coronal reformatted CT image obtained with soft-tissue window settings shows that the prolapsed tissue is orbital fat (arrow). The inferior rectus muscle was displaced, but there was no sign of impingement. Intraorbital gas bubbles (*) are suggestive of a paranasal sinus wall fracture. Note the fissure of the right middle turbinate (arrowhead).
|
|
View larger version (107K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13b. Medium-energy injuries to the left orbital floor and zygomatic complex in a 10-year-old girl after a motor vehicle accident. (a) Axial CT image at the level of the midface shows an impacted left zygomatic complex fracture that involves the zygomatic process of the maxilla and a secondary fracture of the anterior and lateral wall of the maxillary sinus. Note the accumulation of blood in the sinus and the inflammation of periorbital soft tissue. (b) Axial CT image shows a fracture of the lateral wall of the left orbit with several displaced fragments (arrows). (c) Coronal reformatted CT image obtained with bone window settings shows fractures of the frontal (black arrowhead) and maxillary (white arrow) zygomatic processes and a fracture of the orbital floor with a displaced fragment (white arrowhead) and herniation of orbital contents into the maxillary sinus (black arrow). A nondisplaced fracture of the zygomatic arch also was present (not shown). (d) Coronal reformatted CT image obtained with soft-tissue window settings shows that the prolapsed tissue is orbital fat (arrow). The inferior rectus muscle was displaced, but there was no sign of impingement. Intraorbital gas bubbles (*) are suggestive of a paranasal sinus wall fracture. Note the fissure of the right middle turbinate (arrowhead).
|
|
View larger version (108K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13c. Medium-energy injuries to the left orbital floor and zygomatic complex in a 10-year-old girl after a motor vehicle accident. (a) Axial CT image at the level of the midface shows an impacted left zygomatic complex fracture that involves the zygomatic process of the maxilla and a secondary fracture of the anterior and lateral wall of the maxillary sinus. Note the accumulation of blood in the sinus and the inflammation of periorbital soft tissue. (b) Axial CT image shows a fracture of the lateral wall of the left orbit with several displaced fragments (arrows). (c) Coronal reformatted CT image obtained with bone window settings shows fractures of the frontal (black arrowhead) and maxillary (white arrow) zygomatic processes and a fracture of the orbital floor with a displaced fragment (white arrowhead) and herniation of orbital contents into the maxillary sinus (black arrow). A nondisplaced fracture of the zygomatic arch also was present (not shown). (d) Coronal reformatted CT image obtained with soft-tissue window settings shows that the prolapsed tissue is orbital fat (arrow). The inferior rectus muscle was displaced, but there was no sign of impingement. Intraorbital gas bubbles (*) are suggestive of a paranasal sinus wall fracture. Note the fissure of the right middle turbinate (arrowhead).
|
|
View larger version (99K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13d. Medium-energy injuries to the left orbital floor and zygomatic complex in a 10-year-old girl after a motor vehicle accident. (a) Axial CT image at the level of the midface shows an impacted left zygomatic complex fracture that involves the zygomatic process of the maxilla and a secondary fracture of the anterior and lateral wall of the maxillary sinus. Note the accumulation of blood in the sinus and the inflammation of periorbital soft tissue. (b) Axial CT image shows a fracture of the lateral wall of the left orbit with several displaced fragments (arrows). (c) Coronal reformatted CT image obtained with bone window settings shows fractures of the frontal (black arrowhead) and maxillary (white arrow) zygomatic processes and a fracture of the orbital floor with a displaced fragment (white arrowhead) and herniation of orbital contents into the maxillary sinus (black arrow). A nondisplaced fracture of the zygomatic arch also was present (not shown). (d) Coronal reformatted CT image obtained with soft-tissue window settings shows that the prolapsed tissue is orbital fat (arrow). The inferior rectus muscle was displaced, but there was no sign of impingement. Intraorbital gas bubbles (*) are suggestive of a paranasal sinus wall fracture. Note the fissure of the right middle turbinate (arrowhead).
|
|
Maxillary and Zygomatic Fractures
Midfacial fractures are rare in young children; however, their prevalence increases as the maxillary sinuses develop, the deciduous teeth are shed and replaced by permanent teeth, and the face undergoes a downward and forward projection with the midface becoming more prominent and less protected by the skull (1–3,5,6). Fractures of the midface imply high-energy trauma from high-impact or high-velocity forces such as those in motor vehicle accidents or acts of violence (1,6). Midfacial fractures may range from simple minor fractures to complex orbital-zygomaticomalar fractures.
Maxillary fractures occur infrequently in the pediatric population: They account for only 1.2%–20% of pediatric facial fractures (2), and they are second in rarity only to complex fractures. They virtually do not occur in children younger than 2 years. Their prevalence increases as the maxillary sinuses develop and the permanent teeth erupt, usually around the age of 5 years, and it peaks at the age of 13–15 years (1).
Midfacial fractures are easily overlooked, since they are obscured on radiographs by the minimally pneumatized paranasal sinuses and by unerupted tooth buds embedded in the maxillary sinus wall (1). Radiographs therefore are seldom useful. Because the need for absolute anatomic reduction in this region demands high accuracy in imaging (2), the initial diagnostic imaging examination may be performed with CT if there is substantial clinical suspicion of a midfacial fracture (1,6). If it is available, multi–detector row CT with multiplanar reformatting of image data, particularly reformatting in the coronal plane, is the optimal technique. Attention should be given to the nasolacrimal duct, which is frequently injured in such cases, as well as to the infraorbital neural foramen and the orbital floor (a defect in the floor or a prolapse of the orbital contents may indicate a blowout fracture or trapdoor fracture) (1,2,6,23). Fractures with minimal displacement and no occlusal involvement may be managed conservatively, but fractures with severe displacement or with occlusal or orbital involvement require reduction and osteosynthesis (1–5).
Zygomatic complex fractures (Figs 13–15) are the most frequent fractures in the middle region of the face, representing 7%–41% of midfacial fractures (1,2). In children, zygomatic complex fractures often are greenstick fractures involving the lateral wall and floor of the orbit (5). Zygomatic arch fractures in young children cannot be diagnosed on the basis of standard submentovertex views because of superposition of the skull (1). When a fracture of the zygomatic arch is suspected, it is mandatory that all the zygomatic processes (frontal, temporal, and maxillary) be assessed (23). A fractured zygomatic arch may cause impingement of the mandibular coronoid process (1). Images that provide 3D anatomic details are necessary in cases of displaced or comminuted zygomatic complex fractures because good esthetic and functional results may be obtained only by performing reduction at the following three sites: the frontozygomatic suture, the infraorbital rim, and the zygomatic process of the maxilla (5,6).
View larger version (138K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14a. High-energy injuries to the left zygomatic complex in a 14-year-old boy after a fight. (a) Occipitomental radiograph shows an irregularity in the floor of the left orbit (arrowhead) and opacification of the maxillary sinus. (b) Axial CT image shows an impacted fracture of the left maxillary zygomatic process (arrowhead) and accumulated blood in the sinus. (c) Coronal reformatted CT image obtained with soft-tissue window settings shows upward displacement of the orbital contents (arrow) by accumulated blood and bone fragments in the maxillary sinus, but no sign of impingement on the extraocular muscles. (d) Coronal reformatted CT image obtained with bone window settings shows a displaced fragment of the orbital floor (white arrowhead) and a nondisplaced fracture in the zygomatic process of the frontal bone (black arrowhead).
|
|
View larger version (150K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14b. High-energy injuries to the left zygomatic complex in a 14-year-old boy after a fight. (a) Occipitomental radiograph shows an irregularity in the floor of the left orbit (arrowhead) and opacification of the maxillary sinus. (b) Axial CT image shows an impacted fracture of the left maxillary zygomatic process (arrowhead) and accumulated blood in the sinus. (c) Coronal reformatted CT image obtained with soft-tissue window settings shows upward displacement of the orbital contents (arrow) by accumulated blood and bone fragments in the maxillary sinus, but no sign of impingement on the extraocular muscles. (d) Coronal reformatted CT image obtained with bone window settings shows a displaced fragment of the orbital floor (white arrowhead) and a nondisplaced fracture in the zygomatic process of the frontal bone (black arrowhead).
|
|
View larger version (144K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14c. High-energy injuries to the left zygomatic complex in a 14-year-old boy after a fight. (a) Occipitomental radiograph shows an irregularity in the floor of the left orbit (arrowhead) and opacification of the maxillary sinus. (b) Axial CT image shows an impacted fracture of the left maxillary zygomatic process (arrowhead) and accumulated blood in the sinus. (c) Coronal reformatted CT image obtained with soft-tissue window settings shows upward displacement of the orbital contents (arrow) by accumulated blood and bone fragments in the maxillary sinus, but no sign of impingement on the extraocular muscles. (d) Coronal reformatted CT image obtained with bone window settings shows a displaced fragment of the orbital floor (white arrowhead) and a nondisplaced fracture in the zygomatic process of the frontal bone (black arrowhead).
|
|
View larger version (130K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14d. High-energy injuries to the left zygomatic complex in a 14-year-old boy after a fight. (a) Occipitomental radiograph shows an irregularity in the floor of the left orbit (arrowhead) and opacification of the maxillary sinus. (b) Axial CT image shows an impacted fracture of the left maxillary zygomatic process (arrowhead) and accumulated blood in the sinus. (c) Coronal reformatted CT image obtained with soft-tissue window settings shows upward displacement of the orbital contents (arrow) by accumulated blood and bone fragments in the maxillary sinus, but no sign of impingement on the extraocular muscles. (d) Coronal reformatted CT image obtained with bone window settings shows a displaced fragment of the orbital floor (white arrowhead) and a nondisplaced fracture in the zygomatic process of the frontal bone (black arrowhead).
|
|
View larger version (129K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15a. High-energy injuries to the right zygomatic complex in a 12-year-old boy after a motor vehicle accident. (a) Axial CT image shows a comminuted fracture of the right superior orbital rim with depressed fragments and a fracture of the lateral orbital wall. (b) Axial CT image shows an impacted right zygomatic complex fracture and fractures of the anterior and lateral walls of the maxillary sinus, with displaced bone fragments and hemorrhage in the sinus. (c) Coronal reformatted CT image shows displaced fractures of the three zygomatic processes (of frontal, temporal, and maxillary bones) as well as obliteration of the maxillary sinus. (d) Volume-rendered 3D CT image clearly depicts the extent of the fracture.
|
|
View larger version (116K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15b. High-energy injuries to the right zygomatic complex in a 12-year-old boy after a motor vehicle accident. (a) Axial CT image shows a comminuted fracture of the right superior orbital rim with depressed fragments and a fracture of the lateral orbital wall. (b) Axial CT image shows an impacted right zygomatic complex fracture and fractures of the anterior and lateral walls of the maxillary sinus, with displaced bone fragments and hemorrhage in the sinus. (c) Coronal reformatted CT image shows displaced fractures of the three zygomatic processes (of frontal, temporal, and maxillary bones) as well as obliteration of the maxillary sinus. (d) Volume-rendered 3D CT image clearly depicts the extent of the fracture.
|
|
View larger version (137K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15c. High-energy injuries to the right zygomatic complex in a 12-year-old boy after a motor vehicle accident. (a) Axial CT image shows a comminuted fracture of the right superior orbital rim with depressed fragments and a fracture of the lateral orbital wall. (b) Axial CT image shows an impacted right zygomatic complex fracture and fractures of the anterior and lateral walls of the maxillary sinus, with displaced bone fragments and hemorrhage in the sinus. (c) Coronal reformatted CT image shows displaced fractures of the three zygomatic processes (of frontal, temporal, and maxillary bones) as well as obliteration of the maxillary sinus. (d) Volume-rendered 3D CT image clearly depicts the extent of the fracture.
|
|
View larger version (159K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15d. High-energy injuries to the right zygomatic complex in a 12-year-old boy after a motor vehicle accident. (a) Axial CT image shows a comminuted fracture of the right superior orbital rim with depressed fragments and a fracture of the lateral orbital wall. (b) Axial CT image shows an impacted right zygomatic complex fracture and fractures of the anterior and lateral walls of the maxillary sinus, with displaced bone fragments and hemorrhage in the sinus. (c) Coronal reformatted CT image shows displaced fractures of the three zygomatic processes (of frontal, temporal, and maxillary bones) as well as obliteration of the maxillary sinus. (d) Volume-rendered 3D CT image clearly depicts the extent of the fracture.
|
|
Zygomatic complex fractures are classified according to the Manson system (25) by using the following categories: (a) low-energy injuries (minimally displaced or nondisplaced fractures), (b) medium-energy injuries (minimally displaced and mildly comminuted fractures of the zygomatic processes and nondisplaced fractures of the zygomatic arch), and (c) high-energy injuries (severely displaced and comminuted fractures involving the arch and other zygomatic structures) (Figs 14, 15).
|
Complex Fractures
|
|---|
Complex fractures such as naso-orbito-ethmoidal and Le Fort fractures are the least common (1%–8%) facial fractures in children (2,5), but they have the greatest potential to cause future deformity (2). Such fractures may be severely comminuted and displaced, involving the orbital, zygomatic, maxillary, and frontal bones (5).
Naso-orbito-ethmoidal fractures occur in the central upper midface with disruption of the internal orbital walls, ethmoid bone, posterior medial canthal region, and nasal bones (Fig 16). The surgical repair of such fractures is complex and requires proper planning with the aid of accurate CT depiction of the degree of comminution (specifically in the region of the medial canthal ligament insertion into the lacrimal fossa) (23). Special attention also must be paid to the nasofrontal duct, even if the frontal sinus wall is not fractured, since disruption of the duct may cause a future frontal mucocele (23).
View larger version (73K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16a. Complex fractures in a 13-year-old boy after a fall from a bicycle. (a–c) Axial CT images at progressively lower levels show a severely comminuted fracture of frontal bone with a depressed fragment, fractures of the nasal root and ethmoid bone, and a comminuted fracture of the medial canthus. These findings are indicative of a type II naso-orbito-ethmoidal fracture pattern that extends from the nasal base to the maxillary sinuses. Note the increased intercanthal distance (telecanthus) in b. (d) Axial unenhanced brain CT image shows a significant diffuse subarachnoid hemorrhage, a frontal hemorrhagic concussion, and a bilateral frontal subdural hematoma. Type II naso-orbito-ethmoidal fractures are produced by high-energy trauma and therefore are frequently associated with neurocranial injury. (e) Volume-rendered 3D CT image shows the full severity of the fractures, which are likely to cause future deformity.
|
|
View larger version (69K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16b. Complex fractures in a 13-year-old boy after a fall from a bicycle. (a–c) Axial CT images at progressively lower levels show a severely comminuted fracture of frontal bone with a depressed fragment, fractures of the nasal root and ethmoid bone, and a comminuted fracture of the medial canthus. These findings are indicative of a type II naso-orbito-ethmoidal fracture pattern that extends from the nasal base to the maxillary sinuses. Note the increased intercanthal distance (telecanthus) in b. (d) Axial unenhanced brain CT image shows a significant diffuse subarachnoid hemorrhage, a frontal hemorrhagic concussion, and a bilateral frontal subdural hematoma. Type II naso-orbito-ethmoidal fractures are produced by high-energy trauma and therefore are frequently associated with neurocranial injury. (e) Volume-rendered 3D CT image shows the full severity of the fractures, which are likely to cause future deformity.
|
|
View larger version (83K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16c. Complex fractures in a 13-year-old boy after a fall from a bicycle. (a–c) Axial CT images at progressively lower levels show a severely comminuted fracture of frontal bone with a depressed fragment, fractures of the nasal root and ethmoid bone, and a comminuted fracture of the medial canthus. These findings are indicative of a type II naso-orbito-ethmoidal fracture pattern that extends from the nasal base to the maxillary sinuses. Note the increased intercanthal distance (telecanthus) in b. (d) Axial unenhanced brain CT image shows a significant diffuse subarachnoid hemorrhage, a frontal hemorrhagic concussion, and a bilateral frontal subdural hematoma. Type II naso-orbito-ethmoidal fractures are produced by high-energy trauma and therefore are frequently associated with neurocranial injury. (e) Volume-rendered 3D CT image shows the full severity of the fractures, which are likely to cause future deformity.
|
|
View larger version (150K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16d. Complex fractures in a 13-year-old boy after a fall from a bicycle. (a–c) Axial CT images at progressively lower levels show a severely comminuted fracture of frontal bone with a depressed fragment, fractures of the nasal root and ethmoid bone, and a comminuted fracture of the medial canthus. These findings are indicative of a type II naso-orbito-ethmoidal fracture pattern that extends from the nasal base to the maxillary sinuses. Note the increased intercanthal distance (telecanthus) in b. (d) Axial unenhanced brain CT image shows a significant diffuse subarachnoid hemorrhage, a frontal hemorrhagic concussion, and a bilateral frontal subdural hematoma. Type II naso-orbito-ethmoidal fractures are produced by high-energy trauma and therefore are frequently associated with neurocranial injury. (e) Volume-rendered 3D CT image shows the full severity of the fractures, which are likely to cause future deformity.
|
|
View larger version (108K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16e. Complex fractures in a 13-year-old boy after a fall from a bicycle. (a–c) Axial CT images at progressively lower levels show a severely comminuted fracture of frontal bone with a depressed fragment, fractures of the nasal root and ethmoid bone, and a comminuted fracture of the medial canthus. These findings are indicative of a type II naso-orbito-ethmoidal fracture pattern that extends from the nasal base to the maxillary sinuses. Note the increased intercanthal distance (telecanthus) in b. (d) Axial unenhanced brain CT image shows a significant diffuse subarachnoid hemorrhage, a frontal hemorrhagic concussion, and a bilateral frontal subdural hematoma. Type II naso-orbito-ethmoidal fractures are produced by high-energy trauma and therefore are frequently associated with neurocranial injury. (e) Volume-rendered 3D CT image shows the full severity of the fractures, which are likely to cause future deformity.
|
|
Displaced naso-orbito-ethmoidal fractures may be classified according to the Manson system as follows: Type I fractures are characterized by a large bone fragment that contains the insertion site of the medial canthal ligament. In type II fractures, there are several smaller fragments, one of which includes the insertion site of the medial canthal ligament. Type III fractures are comminuted fractures with avulsion of the medial canthal ligament. This avulsion cannot be detected with CT alone, and a physical examination is necessary (23,26).
Le Fort fractures (Fig 17) are uncommon overall, representing 0.5%–26% of all facial fractures in children (2,5). These fractures almost never occur before the age of 2 years (1), and most occur in patients older than 10 years (3). Le Fort fractures involve a disconnection of the maxillary bone from the skull base; the pterygoid process of the sphenoid bone is invariably separated from the maxilla (23). Le Fort fractures are classified in both children and adults according to the following definitions: a type I Le Fort fracture is transmaxillary, a type II Le Fort fracture is pyramidal, and a type III Le Fort fracture involves craniofacial dissociation. Le Fort fractures of a single type are not often seen, and two or more of these three fracture patterns may occur in combination (23).
View larger version (100K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 17a. Right-sided complete type III Le Fort fracture and left-sided incomplete type III Le Fort fracture in a 7-year-old boy after a fall from a bicycle. (a) Axial CT image shows a fracture of the anterior and posterior wall of the right maxillary sinus, as well as bilateral fractures of the pterygoid processes (arrows). (b) Axial CT image shows fractures of the lateral and internal walls of both orbits.
|
|
View larger version (132K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 17b. Right-sided complete type III Le Fort fracture and left-sided incomplete type III Le Fort fracture in a 7-year-old boy after a fall from a bicycle. (a) Axial CT image shows a fracture of the anterior and posterior wall of the right maxillary sinus, as well as bilateral fractures of the pterygoid processes (arrows). (b) Axial CT image shows fractures of the lateral and internal walls of both orbits.
|
|
|
Surgical Treatment
|
|---|
To allow appropriate surgical management of facial fractures, the radiologist must accurately interpret and report the anatomically relevant details, because therapeutic management is tailored to the individual patient (1,2). The effect of treatment on long-term growth and development must be the cornerstone when choosing the optimal therapeutic option (3,5,6). The rule is simple: Be conservative and, to prevent growth disturbance, use minimal manipulation. Treatment should be noninvasive whenever possible, and, when surgery is necessary, the least invasive procedure and least intrusive devices (eg, the fewest and smallest plates) should be used (2,3,5). The goals of treatment are accurate reduction, esthetically pleasing 3D reconstruction, and functional restoration (6). The optimal approach for achieving these goals may vary, depending on the fracture.
Maxillofacial surgical intervention is indicated only for the repair of severely displaced and comminuted fractures that are likely to cause functional impairment, esthetic deformity, or both (7). Nondisplaced, minimally displaced, and greenstick fractures usually are managed conservatively (2–4). The appropriate therapeutic management of pediatric facial fractures according to the fracture characteristics (including anatomic location and, for midfacial and mandibular fractures, the phase of dentition) is summarized in the Table.
There is no clear consensus about the optimal method for fixation of pediatric facial fractures. The implements most commonly used for this purpose are semirigid titanium devices and more recently developed resorbable plating systems (27).
Internal fixation with semirigid titanium plates is controversial (1). These devices once revolutionized the management of facial fractures because they permitted precise reduction, stabilization, and 3D restoration (1,2). However, internal fixation requires an open surgical approach and subperiosteal dissection, which may harm the periosteum and may disturb future growth (1–3). Moreover, a second surgical intervention is required for removal of the fixation devices (1,2). In addition, internally implanted metallic hardware causes artifacts on CT and MR images (1) and thus limits the accuracy of follow-up imaging (6).
Plating systems made of bioabsorbable polymers (3,5,28–31) are an attractive alternative to titanium hardware for the treatment of pediatric facial fractures (7,30–34). The resorbable devices may lessen concern about the long-term effects of internal fixation, and they have the additional advantage of obviating a second surgical procedure for their removal. Moreover, when implanted, these devices do not present the physiologic risks incurred with the use of metallic implants, which may migrate into the cranium (2,5,35,36). Bioabsorbable plates and screws also are invisible on radiographs and are barely noticeable on CT images (Fig 18). They are made of low-attenuating materials that do not produce artifacts on CT and MR images (27,29,30). The therapeutic results observed so far at follow-up CT are promising; however, the information is too recent and too meager as yet to draw any definitive conclusions about long-term outcomes (2,5,27,29–31,33–36).
View larger version (139K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18a. Semirigid titanium hardware and resorbable plating systems used for fixation of a high-energy zygomatic complex fracture in a 12-year-old boy (same patient as in Fig 15). (a) Radiograph (Waters view) shows titanium plates and screws in the right supraorbital rim and the maxillary region. The resorbable plate cannot be seen. (b, c) Coronal reformatted CT images show a resorbable plate as a linear area of slight hyperattenuation in the right orbital floor (arrow). A titanium device also is visible (arrowheads in c).
|
|
View larger version (132K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18b. Semirigid titanium hardware and resorbable plating systems used for fixation of a high-energy zygomatic complex fracture in a 12-year-old boy (same patient as in Fig 15). (a) Radiograph (Waters view) shows titanium plates and screws in the right supraorbital rim and the maxillary region. The resorbable plate cannot be seen. (b, c) Coronal reformatted CT images show a resorbable plate as a linear area of slight hyperattenuation in the right orbital floor (arrow). A titanium device also is visible (arrowheads in c).
|
|
View larger version (126K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18c. Semirigid titanium hardware and resorbable plating systems used for fixation of a high-energy zygomatic complex fracture in a 12-year-old boy (same patient as in Fig 15). (a) Radiograph (Waters view) shows titanium plates and screws in the right supraorbital rim and the maxillary region. The resorbable plate cannot be seen. (b, c) Coronal reformatted CT images show a resorbable plate as a linear area of slight hyperattenuation in the right orbital floor (arrow). A titanium device also is visible (arrowheads in c).
|
|
|
Complications
|
|---|
Complications of pediatric facial fractures are rare overall and occur mainly in cases of severely comminuted and displaced fractures (1). A growth disturbance secondary to a severe fracture (especially a fracture through a vulnerable structure such as the nasal septum, suture lines, and mandibular condyle) occurs in about 15% of pediatric patients with a facial fracture (1,6). Asymmetry may result from the overgrowth or undergrowth of bone. The risk of a growth disturbance should be considered when planning treatment. That risk is not as great in older children, since the facial skeleton is almost fully developed and permanent dentition is nearly complete; fortunately, the most severe fractures (ie, those that require surgery) occur in this group (3).
The pediatric facial skeleton has great potential for growth, and this capability may help improve the long-term outcome of facial fractures (1). Nonunion and fibrous union are almost never seen, because of the greater osteogenic potential and faster healing rate, the more conservative therapeutic procedures used, and the more minimal displacement of fractures in children (1,6).
Facial fractures in children may be complicated by a disturbance of normal dental development, especially during the deciduous and mixed dentition phases (3). However, a spontaneous correction of occlusal malalignment may occur in children as the deciduous teeth are shed and replaced by permanent teeth (1). Ankylosis of the temporomandibular joint occurs in 1%–7% of condylar fractures (1,3).
|
Summary
|
|---|
Facial fractures in children are uncommon overall but occur more frequently in major trauma. Such fractures are found preponderantly in boys, and their prevalence increases with age. The main causes of pediatric facial fractures are motor vehicle accidents and sports-related injuries. Nasal fractures are by far the most prevalent type of facial fracture among children of all ages, but mandibular fractures are the type of pediatric facial fracture most commonly seen in the hospital setting.
Fractures of the pediatric facial skeleton have special characteristics, and specific knowledge is necessary for their diagnosis, management, and follow-up. To understand the differences between pediatric and adult facial fracture patterns, a familiarity with the processes of facial growth and development is essential. Facial growth, paranasal sinus development, dentition, and bone structure all affect the pattern of facial fractures in children. The interpretation of facial radiographs is difficult, especially with regard to features of the midface, and radiography may be most useful for the initial evaluation of low-energy trauma. For the assessment of major facial injuries, especially in patients in whom central nervous system trauma is believed to be present, CT should replace radiography as the initial diagnostic study because it provides the best depiction of facial fractures and because it is mandatory for the evaluation of patients with neurocranial trauma.
Because facial fractures in young children have both esthetic and functional repercussions, the early and accurate identification of such fractures is important. The radiologist can provide essential aid to the pediatrician and the maxillofacial surgeon in planning an optimal therapeutic approach to prevent future growth disturbances.
|
Footnotes
|
|---|
Abbreviations: 3D = three-dimensional
|
References
|
|---|
- Zimmermann CE, Troulis MJ, Kaban LB. Pediatric facial fractures: recent advances in prevention, diagnosis and management. Int J Oral Maxillofac Surg 2006;35(1):2–13.[CrossRef][Medline]
- Haug RH, Foss J. Maxillofacial injuries in the pediatric patient. Oral Surg Oral Med Oral Pathol Radiol Endod 2000;90(2):126–134.[Medline]
- Ferreira PC, Amarante JM, Silva PN, et al. Retrospective study of 1251 maxillofacial fractures in children and adolescents. Plast Reconstr Surg 2005;115(6):1500–1508.[CrossRef][Medline]
- Holland AJ, Broome C, Steinberg A, Cass DT. Facial fractures in children. Pediatr Emerg Care 2001;17(3):157–160.[CrossRef][Medline]
- Faust RA, Younes AA, Gottlieb W, Phillips CD. Maxillary fractures in children. WebMD Web site. http://www.emedicine.com/ent/topic491.htm. Updated June 9, 2006. Accessed March 17, 2007.
- Pachigolla R. Pediatric facial trauma. Grand rounds presentation, Department of Otolaryngology, University of Texas Medical Branch, Galveston, Tex. http://www.utmb.edu/otoref/Grnds/Ped-facial-trauma-9905/Ped-facial-trauma-9905.pdf. Published May 12, 1999. Accessed April 2, 2007.
- Triana RJ, Shockley WW. Pediatric zygomatico-orbital complex fractures: the use of resorbable plating systems—a case report. J Craniomaxillofac Trauma 1998;4(4):32–36.[Medline]
- Anderson PJ. Fractures of the facial skeleton in children. Injury 1995;26(1):47–50.[CrossRef][Medline]
- Gussack GS, Luterman A, Powell RW, Rodgers K, Ramenofsky ML. Pediatric maxillofacial trauma: unique features in diagnosis and treatment. Laryngoscope 1987;97(8 pt 1):925–930.[Medline]
- Shah RK, Dhingra JK, Carter BL, Rebeiz EE. Paranasal sinus development: a radiographic study. Laryngoscope 2003;113(2):205–209.[CrossRef][Medline]
- Kaban LB. Diagnosis and treatment of fractures of the facial bones in children 1943–1993. J Oral Maxillofac Surg 1993;51(7):722–729.[Medline]
- McCann PJ, Brockebank LM, Ayoub AF. Assessment of zygomatico-orbital complex fractures using ultrasonography. Br J Oral Maxillofac Surg 2000;38(5):525–529.[CrossRef][Medline]
- Friedrich RE, Heiland M, Bartel-Friedrich S. Potentials of ultrasound in the diagnosis of midfacial fractures. Clin Oral Invest 2003;7(4):226–229.[CrossRef][Medline]
- Tsiklakis K, Donta C, Gavala S, Karayianni K, Kamenopoulou V, Hourdakis CJ. Dose reduction in maxillofacial imaging using low dose cone beam CT. Eur J Radiol 2005;56(3):413–417.[CrossRef][Medline]
- Schulze D, Heiland M, Thurmann H, Adam G. Radiation exposure during midfacial imaging using 4- and 16-section computed tomography, cone beam computed tomography systems and conventional radiography. Dentomaxillofac Radiol 2004;33(2):83–86.[Abstract/Free Full Text]
- Diederichs CG, Engelke WG, Richter B, Hermann KP, Oestmann J. Must radiation dose for CT of the maxilla and mandible be higher than that for conventional panoramic radiography? AJNR Am J Neuroradiol 1996;17(9):1758–1760.[Abstract]
- Cohnen M, Fischer H, Hamacher J, Lins E, Kötter R, Mödder U. CT of the head by use of reduced current and kilovoltage: relationship between image quality and dose reduction. AJNR Am J Neuroradiol 2000;21(9):1654–1660.[Abstract/Free Full Text]
- Jank S, Emshoff R, Etzelsdorfer M, Strobl H, Nicasi A, Norer B. Ultrasound versus computed tomography in the imaging of orbital floor fractures. J Oral Maxillofac Surg 2004;62(2):150–154.[CrossRef][Medline]
- Jenkins CN, Thuau H. Ultrasound imaging in assessment of fractures of the orbital floor. Clin Radiol 1997;52(9):708–711.[CrossRef][Medline]
- Savage RR, Valvich C. Hematoma of the nasal septum. Pediatr Rev 2006;27(12):478–479.[Free Full Text]
- Ginsburg CM. Nasal septal hematoma. Pediatr Rev 1998;19(4):142–143.[Free Full Text]
- Toback S. Nasal septal hematoma in an 11-month-old infant: a case report and review of the literature. Pediatr Emerg Care 2003;19(4):265–267.[CrossRef][Medline]
- Hopper RA, Salemy S, Sze RW. Diagnosis of midface fractures with CT: what the surgeon needs to know. RadioGraphics 2006;26(3):783–793.[Abstract/Free Full Text]
- Burm JS. Internal fixation in trapdoor-type orbital blowout fracture. Plast Reconstr Surg 2005;116(4):962–970.[CrossRef][Medline]
- Manson PN, Markowitz B, Mirvis S, et al. Toward CT-based facial fracture treatment. Plast Reconstr Surg 1990;85(2):202–212; discussion 213–214.[Medline]
- Markowitz BL, Manson PN, Sargent L, et al. Management of the medial canthal tendon in nasoethmoid orbital fractures: the importance of the central fragment in classification and treatment. Plast Reconstr Surg 1991;87(5):843–853.[CrossRef][Medline]
- Haug RH, Cunningham LL, Brandt MT. Plates, screws, and children: their relationship in craniomaxillofacial trauma. J Long Term Eff Med Implants 2003;13(4):271–287.[CrossRef][Medline]
- Suuronen R, Kallela I, Lindqvist C. Bioabsorbable plates and screws: current state of the art in facial fracture repair. J Craniomaxillofac Trauma 2000;6(1):19–27.[Medline]
- Tatum SA, Kellman RM, Freije JE. Maxillofacial fixation with absorbable miniplates: computed tomographic follow-up. J Craniofac Surg 1997;8(2):135–140.[Medline]
- Suzuki T, Kawamura H, Kasahara T, Nagasaka H. Resorbable poly-L-lactide plates and screws for the treatment of mandibular condylar process fractures: a clinical and radiological follow-up study. J Oral Maxillofac Surg 2004;62(8):919–924.[CrossRef][Medline]
- Montag ME, Morales L Jr, Daane S. Bioabsorbables: their use in pediatric craniofacial surgery. J Craniofac Surg 1997;8(2):100–102.[Medline]
- Bell RB, Kindsfater CS. The use of biodegradable plates and screws to stabilize facial fractures. J Oral Maxillofac Surg 2006;64(1):31–39.[Medline]
- Kumar AV, Staffenberg DA, Petronio JA, Wood RJ. Bioabsorbable plates and screws in pediatric craniofacial surgery: a review of 22 cases. J Craniofac Surg 1997;8(2):97–99.[Medline]
- Imola MJ, Hamlar DD, Shao W, Chowdhury K, Tatum S. Resorbable plate fixation in pediatric craniofacial surgery: long-term outcome. Arch Facial Plast Surg 2001;3(2):79–90.[Abstract/Free Full Text]
- Eppley BL. Use of resorbable plates and screws in pediatric facial fractures. J Oral Maxillofac Surg 2005;63(3):385–391.[CrossRef][Medline]
- Eppley BL, Morales L, Wood R, et al. Resorbable PLLA-PGA plate and screw fixation in pediatric craniofacial surgery: clinical experience in 1883 patients. Plast Reconstr Surg 2004;114(4):850–856.[CrossRef][Medline]
Top
Abstract
LEARNING OBJECTIVES FOR TEST...
