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Mandible fracture patterns: A suburban trauma center experience
Original Contributions Mandible Fracture Patterns: A Suburban Trauma Center Experience Robert E. King, MD, Joseph M. Scianna, MD, and Guy J. Petruzzelli, MD, PhD Purpose: Mandible fractures are among the most frequently seen injuries in the trauma center setting. Recent shifts in the mechanism and age distribution of patients sustaining these injuries are well documented. This study attempts to define current, predictable patterns of fracture based on patient characteristics and mechanism of injury. Material and Methods: The charts of 134 patients with 225 mandible fractures treated over a 7-year period by the Otolaryngology–Head and Neck Surgery, Plastic and Reconstructive Surgery and Oral-Maxillofacial Surgery services, our institution, were retrospectively reviewed. Patients were categorized based on age, mechanism of fracture, and anatomic location of fracture. Multivariate analysis of data was performed to determine significant relationships among groups. Results: Violent crimes such as assault and gunshot wounds accounted for the majority of fractures (50%) in this study, with motor vehicle accidents less likely (29%). Overall, parasymphyseal fractures were most frequent (35%), whereas angle and body fractures were also common (15% and 21%, respectively). There was a statistically significant association of motor vehicle accidents with parasymphyseal fractures (45%), and gunshot wounds with body fractures (36%), whereas assault victims had a higher than predicted frequency of angle fractures (27%) and fewer parasymphyseal fractures (19%). Patients aged 17 to 30 were more likely to suffer from gunshot wounds, whereas older adults (age 31-50) were more likely to be assault victims. Patients over age 50 suffered fractures from falls at a higher than expected rate. Although children and young adults seemed to suffer more parasymphyseal fractures and older adults body fractures, these correlations failed to show statistical significance. Parasymphyseal fractures were most frequently associated with fractures at other sites within the mandible, ipsilateral body fractures being the most common. Conclusions: Updated data on the association of patient age and mechanism of injury with fracture pattern can guide treating physicians in anticipating and diagnosing traumatic mandible fractures. (Am J Otolaryngol 2004;25:301-307. © 2004 Elsevier Inc. All rights reserved.)
Mandible fracture is among the most frequently encountered injuries in the trauma center setting and represents the second most commonly fractured bone in the facial skeleton. These fractures can involve any of a number of anatomic subsites within the mandible and often involve multiple anatomic sites simultaneously. Although local patterns and
From the Department of Otolaryngology, Head and Neck Surgery, Loyola University Medical Center, Maywood, IL. Address correspondence to: Guy J. Petruzzelli, MD, PhD, 2160 South First Avenue, Bldg 105, Room 1870, Maywood, IL 60153. E-mail: [email protected]. © 2004 Elsevier Inc. All rights reserved. 0196-0709/$ - see front matter doi:10.1016/j.amjoto.2004.03.001
causes of mandible fractures vary considerably among different study populations, recent overall shifts in the mechanism of injury and age distribution of patients sustaining these injuries are well documented.1-5 There is an emerging trend toward an increase in the frequency of violent mechanisms for fracture and an increase in the proportion of adolescents and young adults sustaining these injuries. These trends seem to hold especially true in urban settings.6-11 This study attempts to define current, predictable patterns of fracture based on patient demographics and mechanism of injury at a major urban trauma center. Also, in cases of multiple site fractures, association between specific anatomic sites is sought. The development of reliable predic-
American Journal of Otolaryngology, Vol 25, No 5 (September-October), 2004: pp 301-307
301
302
KING ET AL
Fig 1.
Mechanism of injury distribution. Figure can be viewed in color online.
tors of injury patterns will be a useful guide to the prompt and accurate diagnosis and management of mandible fractures in the trauma patient population. MATERIAL AND METHODS The medical records of 134 patients with mandible fractures treated over a 7-year period by the Otolaryngology–Head and Neck Surgery, Plastic and Reconstructive Surgery, and Oral-Maxillofacial Surgery services at a suburban trauma center were retrospectively reviewed. All patients received a panorex and/or bone algorithm computed tomography scan to evaluate the fracture pattern. Fracture sites were assigned 1 of 7 different mandibular subsites including angle, body, ramus, subcondyle, condyle, symphysis/parasymphysis, and alveolus based on documented radiographic and/or intraoperative findings. Patient data were recorded with respect to gender and age. Ages were grouped into 1 of 4 categories: 0 to 16 years old, 17 to 30 years old, 31 to 50 years old, and ⬎50 years old. Mechanism of injury was recorded based on emergency room or trauma bay records and classified as assault, motor vehicle collision (MVC) (including motorcycle accidents), gunshot wound, fall, pedestrian struck by car, and other causes. Gunshot wounds and assaults were also combined to yield data on violent crime as a whole. The use of supplemental restraints in cases of motor vehicle accidents and the presence of simultaneous, nonmandibular facial skeletal fractures were also recorded.
Multivariate analysis of data was performed to determine statistically significant relationships among groups. Specifically, associations between mechanism of fracture and age, mechanism of fracture and fracture site, and age and fracture site were calculated. Differences from expected values based on a random association were determined by using a chi-square analysis, and those with P values ⬍.05 were considered significant.
RESULTS A total of 225 mandible fractures sustained by 134 patients were studied. Of these patients, 110 were men and 24 were women, yielding a ratio of 4.6:1. The mean age was 32, and 40 patients (29.9%) had associated nonmandibular facial fractures. Violent crimes including assault and gunshot wounds accounted for the largest proportion of fractures (49.3%) in this study, whereas motor vehicle accidents were the second most likely cause (29.9%). Fall represented 13.4%, pedestrians struck by car represented 3.7%, and other injuries accounted for 3.7% of fractures (Fig 1). Eighty-five percent of patients sustaining mandibular fractures in motor vehicle accidents were not wearing seat belts or had deployment of airbags. Overall, parasymphyseal fractures were most frequent (34.2%),
MANDIBLE FRACTURE PATTERNS
Fig 2.
303
Anatomic site distribution. Figure can be viewed in color online.
whereas angle and body fractures were also common (14.6% and 20.8%, respectively). Subcondylar fractures accounted for 13.7%, condylar fractures for 9.3%, ramus fractures for 5.7%, and alveolar ridge fractures for 1.3% (Fig 2). Seventeen- to 30-year olds were the most commonly involved age group (42.5%) and 31- to 50-year olds were the second most common (29.9%). Patients younger than 16 and those older than 50 years of age represented 14.2% and 13.4% of patients, respectively (Fig 3). There was a statistically significant (P ⬍ .05) association of motor vehicle accidents with parasymphyseal fractures and gunshot wounds with body fractures, whereas assault victims had a higher than predicted frequency of angle fractures and fewer parasymphyseal fractures. Victims of falls and patients struck by automobiles were very likely to suffer condylar fractures (Table 1). Patients aged 17 to
30 were more likely to suffer from gunshot wounds, whereas adults between the ages of 31 and 50 were more likely to be victims of assault. Patients over age 50 suffered fractures from falls at a higher than expected rate (Table 2). Although children and young adults seemed to suffer more parasymphyseal fractures and older adults body fractures, these correlations failed to show statistical significance. Overall, 67.9% of patients sustained fractures in multiple sites within the mandible. Analysis of clustering of fracture sites within these patients revealed that symphyseal/parasymphyseal fractures were most commonly (63.3%) associated with a second fracture at a different location within the mandible (Fig 4). Twenty-three percent of these were associated with contralateral fractures; subcondylar fractures represented the most common site. Seventy-seven percent were associated with ipsi-
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KING ET AL
Fig 3.
Age distribution. Figure can be viewed in color online.
lateral fractures, most commonly in the body region. With regards to mechanism, 59.6% of assaults and 57.8% of gunshot wounds led to multiple-site fractures. Half (50.0%) of falls and 42.5% of MVCs resulted in multisite fractures. Patients struck by cars had a 40.0% chance of suffering multiple mandibular fractures (Fig 5). DISCUSSION During the 1970s, there began a documented shift in the mechanism of injury leading to mandible fractures in both the United States and Europe.1-4,6 Specifically, violence and sporting injuries were noted to be accounting for a larger proportion of mandible
fractures. Before this time, motor vehicle crashes caused the large majority of mandible fractures in all patient populations, whereas more recent studies show assault, fights, gunshot wounds, and other acts of violence as the largest contributors to these injuries. These trends seem to hold especially true for urban settings, whereas rural communities still show a significant number of fractures from automobile accidents.6-11 Also noted is a trend toward relatively fewer young children and more adolescents and young adults being treated for mandible fractures.3,5,6 Many attribute these shifts to both a rising societal incidence of violent crime, especially among the adolescent population, and increased or mandatory use of supplemental restraint devices such as seat belts, airbags, and child
TABLE 1. Mechanism of Injury Versus Anatomic Site
Angle Body Ramus Subcondyle Condyle Symphysis/parasymphysis Alveolus
Assault (%)
MVC (%)
Gunshot Wound (%)
Fall (%)
SBC (%)
26.92* 25.64 10.26 14.10 3.85 19.23† 0
10.94 10.94† 6.25 17.19 6.25 45.31* 3.13
5.56 36.11* 11.11 2.78 0† 44.44 0
9.38 25.00 0 12.50 21.88* 28.13 3.13
0 12.50 0 0 50.00* 37.50 0
Abbreviation: SBC, struck by car. *Statistically significant (P ⬍ .05) increase in observed incidence over expected incidence. †Statistically significant (P ⬍ .05) decrease in observed incidence from expected incidence.
MANDIBLE FRACTURE PATTERNS
305
TABLE 2. Age Versus Mechanism of Injury
Assault MVC Gunshot wound Fall SBC
0-16 Years (%)
17-30 Years (%)
31-50 Years (%)
⬎50 Years (%)
15.79 26.32 26.32 21.05 10.53
30.36 37.50 23.21* 7.14 1.79
64.10* 20.51 0† 12.82 2.56
13.33 40.00 6.67 33.33* 6.67
Abbreviation: SBC, struck by car. *Statistically significant (P ⬍ .05) increase in observed incidence over expected incidence. †Statistically significant (P ⬍ .05) decrease in observed incidence from expected incidence.
restraint seats in automobiles.1,3 The current study shows a continuation of the urban trend toward violence as an ever-increasing cause of mandible fracture in a major suburban trauma center. Although motor vehicle accidents have historically been the leading cause of mandible fractures in trauma patients, less than one third of patients in our study were involved in accidents of this sort. Violent crimes accounted for nearly half of the mandible fractures seen in our patient population, and the presence of mandibular injury should be suspected in all victims of these crimes. The likelihood of mandible fractures being caused by falls or patients being struck by cars remains stable when compared with previous studies. Histori-
Fig 4.
cally, children less than 16 years of age were the most common age group to sustain a fracture of the mandible. In the current population, the large majority of fractures were seen in adolescents and young adults (ages 17-30). Very few patients (less than 15%) were seen to be at the extremes of age range. Again, this correlates with previously observed trends toward relatively fewer childhood fractures. This shift seems to correlate with the increasing and, in some cases mandated, use of child restraint seats and seat belts for passengers in automobiles in this country. Of those sustaining fractures in motor vehicle accidents, only 15% were wearing seat belts and/or had evidence of airbag deployment. It seems plausible, therefore, to attribute the relative decrease in fractures
Frequency of concomitant second mandible fracture by site. Figure can be viewed in color online.
306
Fig 5. Frequency of concomitant second mandible fracture by mechanism of injury. Figure can be viewed in color online.
among children and because of MVCs to increased automobile safety measures. The mechanism of patient injury correlates significantly with the anatomic location of fracture, and knowledge of these associations should guide treating physicians in their diagnostic workup of all head and neck trauma patients. Victims of violent crimes such as assault and gunshot wounds are statistically significantly more likely to suffer body and angle fractures and fewer than expected parasymphyseal fractures. Automobile accident victims will more commonly have symphyseal/ parasymphyseal fractures and fewer body fractures than expected. Assault victims, especially those suffering trauma such as from a fist or other blunt object, will more commonly receive a blow to lateral portions of the jaw, predisposing these patients to fractures at lateral locations such as the angle and body. Automobile accident victims, especially those not wearing seat belts or having airbag deployment, commonly suffer posterior directed force to the mandible as a result of the chin striking the steering wheel or dashboard. Consequently, the preponderance of symphyseal and parasymphyseal fractures is intuitive. Patients involved in accidents involving posterosuperiorly directed energy such as falls and being struck by vehicles where the underside of the anterior mandible receives the primary force of impact should be suspected of having condylar and subcondylar injuries. The data herein support this concept.
KING ET AL
With regards to patient characteristics, there exists a significant association between patient age and mechanism of injury within certain age groups. In patients less than 16 years of age, no one mechanism of injury predominated, whereas in the 17- to 30-year age group, an observed increase in gunshot wounds as a cause of fracture was seen. In all probability, this is because of the fact that, in the urban setting, this age group is the most commonly involved in crimes with a weapon and in gang-related activity. Adults aged 31 to 50 were more commonly victims of assault not involving a gun. Finally, those older than 50 suffered falls at a greater than expected rate, likely because of decreasing mobility and balance in the more elderly portion of this age group. There existed no statistically significant association of any patient age group with any specific mandibular fracture site when controlling associations among age and mechanism of injury. This suggests that fracture site is dependent primarily on the physics of the specific injury mechanism and not on any inherent characteristics of the mandible itself such as the absence of dentition or presence of unerupted third molars. Also, despite theories that the pediatric mandible is more likely to undergo single-site fracture because of the inherent pliability of the younger bone, we failed to show a significant increase in singleor multiple-site fractures in any one age group. Previous studies have shown a preponderance of single-site mandible fractures, whereas the population studied here had a greater than 60% chance of suffering multiple-site injury. This can be attributed to the high proportion of assaults and gunshot wounds, which showed the highest likelihood of causing fractures at more than 1 site. Perhaps the lateralized force profile of these injuries accounts for this pattern because body and parasymphyseal fractures show the greatest association with second fractures independent of mechanism of injury. Although all patients with mandible fractures should be suspected of having a second fracture site within the mandible, this holds especially true for symphyseal and parasymphyseal fractures. Treating physicians should be particularly concerned
MANDIBLE FRACTURE PATTERNS
about contralateral subcondylar and ipsilateral body fractures in these patients. CONCLUSION Updated data on overall patterns and demographic correlations in traumatic mandible fracture patients can guide treating physicians in anticipating these injuries, leading to more accurate and timely diagnosis and more effective treatment. Violent crime and motor vehicle crashes continue to account for the majority of mandibular injury, while there is a shifting trend toward more violence and fewer pediatric patients. REFERENCES 1. Van Beek GJ, Merkx CA: Changes in the pattern of fractures of the maxillofacial skeleton. Int J Oral Maxillofac Surg 28:424-428, 1999 2. Busioto MJ, Smith DJ, Robson MC: Mandibular fractures in an urban trauma center. J Trauma 26:826-829, 1986
307
3. Azevedo AB, Trent RB, Ellis A: Population based analysis of 10,766 hospitalizations for mandibular fractures in California. J Trauma 45:1084-1087, 1998 4. Sojot AJ, Meisami T, Sandor GK, et al: The epidemiology of mandibular fractures treated at the Toronto general hospital: A review of 246 cases. J Can Dental Assoc 67:640-644, 2001 5. Atanasov DT, Vuvakis VM: Mandibular fractures in children. A retrospective study. Folia Medica 42:65-70, 2000 6. Boole JR, Holtel M, Amoroso P, et al: 5196 mandible fractures among 4381 active duty army soldiers, 19801998. Laryngoscope 111:1691-1696, 2001 7. Carlin CB, Ruff G, Mansfield CP, et al: Facial Fractures and related injuries: A ten year retrospective analysis. J Craniomaxillofac Trauma 4:44-48, 1998 8. Fridrich K, Pena-Velasco G, Olson R: Changing trends with mandibular fractures: A review of 1067 cases. J Oral Maxillofac Surg 50:586-589, 1992 9. Olson R, Fonseca R, Zeitler D, et al: Fractures of the mandible: A review of 580 cases. J Oral Maxillofac Surg 40:23-28, 1982 10. Scherer M, Sullivan W, Smith D, et al: An analysis of 1423 facial fractures in 788 patients at an urban trauma center. J Trauma 29:388-390, 1989 11. Haug R, Prather J, Indresano T: An epidemiologic survey of facial fractures and concomitant injuries. J Oral Maxillofac Surg 48:635-638, 1990
Mandible fracture is among the most frequently encountered injuries in the trauma center setting and represents the second most commonly fractured bone in the facial skeleton. These fractures can involve any of a number of anatomic subsites within the mandible and often involve multiple anatomic sites simultaneously. Although local patterns and
From the Department of Otolaryngology, Head and Neck Surgery, Loyola University Medical Center, Maywood, IL. Address correspondence to: Guy J. Petruzzelli, MD, PhD, 2160 South First Avenue, Bldg 105, Room 1870, Maywood, IL 60153. E-mail: [email protected]. © 2004 Elsevier Inc. All rights reserved. 0196-0709/$ - see front matter doi:10.1016/j.amjoto.2004.03.001
causes of mandible fractures vary considerably among different study populations, recent overall shifts in the mechanism of injury and age distribution of patients sustaining these injuries are well documented.1-5 There is an emerging trend toward an increase in the frequency of violent mechanisms for fracture and an increase in the proportion of adolescents and young adults sustaining these injuries. These trends seem to hold especially true in urban settings.6-11 This study attempts to define current, predictable patterns of fracture based on patient demographics and mechanism of injury at a major urban trauma center. Also, in cases of multiple site fractures, association between specific anatomic sites is sought. The development of reliable predic-
American Journal of Otolaryngology, Vol 25, No 5 (September-October), 2004: pp 301-307
301
302
KING ET AL
Fig 1.
Mechanism of injury distribution. Figure can be viewed in color online.
tors of injury patterns will be a useful guide to the prompt and accurate diagnosis and management of mandible fractures in the trauma patient population. MATERIAL AND METHODS The medical records of 134 patients with mandible fractures treated over a 7-year period by the Otolaryngology–Head and Neck Surgery, Plastic and Reconstructive Surgery, and Oral-Maxillofacial Surgery services at a suburban trauma center were retrospectively reviewed. All patients received a panorex and/or bone algorithm computed tomography scan to evaluate the fracture pattern. Fracture sites were assigned 1 of 7 different mandibular subsites including angle, body, ramus, subcondyle, condyle, symphysis/parasymphysis, and alveolus based on documented radiographic and/or intraoperative findings. Patient data were recorded with respect to gender and age. Ages were grouped into 1 of 4 categories: 0 to 16 years old, 17 to 30 years old, 31 to 50 years old, and ⬎50 years old. Mechanism of injury was recorded based on emergency room or trauma bay records and classified as assault, motor vehicle collision (MVC) (including motorcycle accidents), gunshot wound, fall, pedestrian struck by car, and other causes. Gunshot wounds and assaults were also combined to yield data on violent crime as a whole. The use of supplemental restraints in cases of motor vehicle accidents and the presence of simultaneous, nonmandibular facial skeletal fractures were also recorded.
Multivariate analysis of data was performed to determine statistically significant relationships among groups. Specifically, associations between mechanism of fracture and age, mechanism of fracture and fracture site, and age and fracture site were calculated. Differences from expected values based on a random association were determined by using a chi-square analysis, and those with P values ⬍.05 were considered significant.
RESULTS A total of 225 mandible fractures sustained by 134 patients were studied. Of these patients, 110 were men and 24 were women, yielding a ratio of 4.6:1. The mean age was 32, and 40 patients (29.9%) had associated nonmandibular facial fractures. Violent crimes including assault and gunshot wounds accounted for the largest proportion of fractures (49.3%) in this study, whereas motor vehicle accidents were the second most likely cause (29.9%). Fall represented 13.4%, pedestrians struck by car represented 3.7%, and other injuries accounted for 3.7% of fractures (Fig 1). Eighty-five percent of patients sustaining mandibular fractures in motor vehicle accidents were not wearing seat belts or had deployment of airbags. Overall, parasymphyseal fractures were most frequent (34.2%),
MANDIBLE FRACTURE PATTERNS
Fig 2.
303
Anatomic site distribution. Figure can be viewed in color online.
whereas angle and body fractures were also common (14.6% and 20.8%, respectively). Subcondylar fractures accounted for 13.7%, condylar fractures for 9.3%, ramus fractures for 5.7%, and alveolar ridge fractures for 1.3% (Fig 2). Seventeen- to 30-year olds were the most commonly involved age group (42.5%) and 31- to 50-year olds were the second most common (29.9%). Patients younger than 16 and those older than 50 years of age represented 14.2% and 13.4% of patients, respectively (Fig 3). There was a statistically significant (P ⬍ .05) association of motor vehicle accidents with parasymphyseal fractures and gunshot wounds with body fractures, whereas assault victims had a higher than predicted frequency of angle fractures and fewer parasymphyseal fractures. Victims of falls and patients struck by automobiles were very likely to suffer condylar fractures (Table 1). Patients aged 17 to
30 were more likely to suffer from gunshot wounds, whereas adults between the ages of 31 and 50 were more likely to be victims of assault. Patients over age 50 suffered fractures from falls at a higher than expected rate (Table 2). Although children and young adults seemed to suffer more parasymphyseal fractures and older adults body fractures, these correlations failed to show statistical significance. Overall, 67.9% of patients sustained fractures in multiple sites within the mandible. Analysis of clustering of fracture sites within these patients revealed that symphyseal/parasymphyseal fractures were most commonly (63.3%) associated with a second fracture at a different location within the mandible (Fig 4). Twenty-three percent of these were associated with contralateral fractures; subcondylar fractures represented the most common site. Seventy-seven percent were associated with ipsi-
304
KING ET AL
Fig 3.
Age distribution. Figure can be viewed in color online.
lateral fractures, most commonly in the body region. With regards to mechanism, 59.6% of assaults and 57.8% of gunshot wounds led to multiple-site fractures. Half (50.0%) of falls and 42.5% of MVCs resulted in multisite fractures. Patients struck by cars had a 40.0% chance of suffering multiple mandibular fractures (Fig 5). DISCUSSION During the 1970s, there began a documented shift in the mechanism of injury leading to mandible fractures in both the United States and Europe.1-4,6 Specifically, violence and sporting injuries were noted to be accounting for a larger proportion of mandible
fractures. Before this time, motor vehicle crashes caused the large majority of mandible fractures in all patient populations, whereas more recent studies show assault, fights, gunshot wounds, and other acts of violence as the largest contributors to these injuries. These trends seem to hold especially true for urban settings, whereas rural communities still show a significant number of fractures from automobile accidents.6-11 Also noted is a trend toward relatively fewer young children and more adolescents and young adults being treated for mandible fractures.3,5,6 Many attribute these shifts to both a rising societal incidence of violent crime, especially among the adolescent population, and increased or mandatory use of supplemental restraint devices such as seat belts, airbags, and child
TABLE 1. Mechanism of Injury Versus Anatomic Site
Angle Body Ramus Subcondyle Condyle Symphysis/parasymphysis Alveolus
Assault (%)
MVC (%)
Gunshot Wound (%)
Fall (%)
SBC (%)
26.92* 25.64 10.26 14.10 3.85 19.23† 0
10.94 10.94† 6.25 17.19 6.25 45.31* 3.13
5.56 36.11* 11.11 2.78 0† 44.44 0
9.38 25.00 0 12.50 21.88* 28.13 3.13
0 12.50 0 0 50.00* 37.50 0
Abbreviation: SBC, struck by car. *Statistically significant (P ⬍ .05) increase in observed incidence over expected incidence. †Statistically significant (P ⬍ .05) decrease in observed incidence from expected incidence.
MANDIBLE FRACTURE PATTERNS
305
TABLE 2. Age Versus Mechanism of Injury
Assault MVC Gunshot wound Fall SBC
0-16 Years (%)
17-30 Years (%)
31-50 Years (%)
⬎50 Years (%)
15.79 26.32 26.32 21.05 10.53
30.36 37.50 23.21* 7.14 1.79
64.10* 20.51 0† 12.82 2.56
13.33 40.00 6.67 33.33* 6.67
Abbreviation: SBC, struck by car. *Statistically significant (P ⬍ .05) increase in observed incidence over expected incidence. †Statistically significant (P ⬍ .05) decrease in observed incidence from expected incidence.
restraint seats in automobiles.1,3 The current study shows a continuation of the urban trend toward violence as an ever-increasing cause of mandible fracture in a major suburban trauma center. Although motor vehicle accidents have historically been the leading cause of mandible fractures in trauma patients, less than one third of patients in our study were involved in accidents of this sort. Violent crimes accounted for nearly half of the mandible fractures seen in our patient population, and the presence of mandibular injury should be suspected in all victims of these crimes. The likelihood of mandible fractures being caused by falls or patients being struck by cars remains stable when compared with previous studies. Histori-
Fig 4.
cally, children less than 16 years of age were the most common age group to sustain a fracture of the mandible. In the current population, the large majority of fractures were seen in adolescents and young adults (ages 17-30). Very few patients (less than 15%) were seen to be at the extremes of age range. Again, this correlates with previously observed trends toward relatively fewer childhood fractures. This shift seems to correlate with the increasing and, in some cases mandated, use of child restraint seats and seat belts for passengers in automobiles in this country. Of those sustaining fractures in motor vehicle accidents, only 15% were wearing seat belts and/or had evidence of airbag deployment. It seems plausible, therefore, to attribute the relative decrease in fractures
Frequency of concomitant second mandible fracture by site. Figure can be viewed in color online.
306
Fig 5. Frequency of concomitant second mandible fracture by mechanism of injury. Figure can be viewed in color online.
among children and because of MVCs to increased automobile safety measures. The mechanism of patient injury correlates significantly with the anatomic location of fracture, and knowledge of these associations should guide treating physicians in their diagnostic workup of all head and neck trauma patients. Victims of violent crimes such as assault and gunshot wounds are statistically significantly more likely to suffer body and angle fractures and fewer than expected parasymphyseal fractures. Automobile accident victims will more commonly have symphyseal/ parasymphyseal fractures and fewer body fractures than expected. Assault victims, especially those suffering trauma such as from a fist or other blunt object, will more commonly receive a blow to lateral portions of the jaw, predisposing these patients to fractures at lateral locations such as the angle and body. Automobile accident victims, especially those not wearing seat belts or having airbag deployment, commonly suffer posterior directed force to the mandible as a result of the chin striking the steering wheel or dashboard. Consequently, the preponderance of symphyseal and parasymphyseal fractures is intuitive. Patients involved in accidents involving posterosuperiorly directed energy such as falls and being struck by vehicles where the underside of the anterior mandible receives the primary force of impact should be suspected of having condylar and subcondylar injuries. The data herein support this concept.
KING ET AL
With regards to patient characteristics, there exists a significant association between patient age and mechanism of injury within certain age groups. In patients less than 16 years of age, no one mechanism of injury predominated, whereas in the 17- to 30-year age group, an observed increase in gunshot wounds as a cause of fracture was seen. In all probability, this is because of the fact that, in the urban setting, this age group is the most commonly involved in crimes with a weapon and in gang-related activity. Adults aged 31 to 50 were more commonly victims of assault not involving a gun. Finally, those older than 50 suffered falls at a greater than expected rate, likely because of decreasing mobility and balance in the more elderly portion of this age group. There existed no statistically significant association of any patient age group with any specific mandibular fracture site when controlling associations among age and mechanism of injury. This suggests that fracture site is dependent primarily on the physics of the specific injury mechanism and not on any inherent characteristics of the mandible itself such as the absence of dentition or presence of unerupted third molars. Also, despite theories that the pediatric mandible is more likely to undergo single-site fracture because of the inherent pliability of the younger bone, we failed to show a significant increase in singleor multiple-site fractures in any one age group. Previous studies have shown a preponderance of single-site mandible fractures, whereas the population studied here had a greater than 60% chance of suffering multiple-site injury. This can be attributed to the high proportion of assaults and gunshot wounds, which showed the highest likelihood of causing fractures at more than 1 site. Perhaps the lateralized force profile of these injuries accounts for this pattern because body and parasymphyseal fractures show the greatest association with second fractures independent of mechanism of injury. Although all patients with mandible fractures should be suspected of having a second fracture site within the mandible, this holds especially true for symphyseal and parasymphyseal fractures. Treating physicians should be particularly concerned
MANDIBLE FRACTURE PATTERNS
about contralateral subcondylar and ipsilateral body fractures in these patients. CONCLUSION Updated data on overall patterns and demographic correlations in traumatic mandible fracture patients can guide treating physicians in anticipating these injuries, leading to more accurate and timely diagnosis and more effective treatment. Violent crime and motor vehicle crashes continue to account for the majority of mandibular injury, while there is a shifting trend toward more violence and fewer pediatric patients. REFERENCES 1. Van Beek GJ, Merkx CA: Changes in the pattern of fractures of the maxillofacial skeleton. Int J Oral Maxillofac Surg 28:424-428, 1999 2. Busioto MJ, Smith DJ, Robson MC: Mandibular fractures in an urban trauma center. J Trauma 26:826-829, 1986
307
3. Azevedo AB, Trent RB, Ellis A: Population based analysis of 10,766 hospitalizations for mandibular fractures in California. J Trauma 45:1084-1087, 1998 4. Sojot AJ, Meisami T, Sandor GK, et al: The epidemiology of mandibular fractures treated at the Toronto general hospital: A review of 246 cases. J Can Dental Assoc 67:640-644, 2001 5. Atanasov DT, Vuvakis VM: Mandibular fractures in children. A retrospective study. Folia Medica 42:65-70, 2000 6. Boole JR, Holtel M, Amoroso P, et al: 5196 mandible fractures among 4381 active duty army soldiers, 19801998. Laryngoscope 111:1691-1696, 2001 7. Carlin CB, Ruff G, Mansfield CP, et al: Facial Fractures and related injuries: A ten year retrospective analysis. J Craniomaxillofac Trauma 4:44-48, 1998 8. Fridrich K, Pena-Velasco G, Olson R: Changing trends with mandibular fractures: A review of 1067 cases. J Oral Maxillofac Surg 50:586-589, 1992 9. Olson R, Fonseca R, Zeitler D, et al: Fractures of the mandible: A review of 580 cases. J Oral Maxillofac Surg 40:23-28, 1982 10. Scherer M, Sullivan W, Smith D, et al: An analysis of 1423 facial fractures in 788 patients at an urban trauma center. J Trauma 29:388-390, 1989 11. Haug R, Prather J, Indresano T: An epidemiologic survey of facial fractures and concomitant injuries. J Oral Maxillofac Surg 48:635-638, 1990