PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 26 no. 1 January – June 2011 ORIGINAL ARTICLES 16 PhiliPPine Journal of otolaryngology-head and neck Surgery Philipp J Otolaryngol Head Neck Surg 2011; 26 (1): 16-20 c Philippine Society of Otolaryngology – Head and Neck Surgery, Inc. ABSTRACT Objectives: The study aimed to evaluate mandibular fractures in a tertiary military hospital, to determine the age group in which injury occurred most often, to examine the various mechanisms of injury, to determine the anatomical part of the mandible most frequently affected and to determine if there were significant relationships between the various mechanisms of injury and the different fracture sites. Methods: Design: Cross-sectional retrospective study Setting: Tertiary Public Military Hospital Patients: Medical records of 328 active military personnel and their dependents, treated for mandibular fracture at the Department of Otorhinolaryngology – Head and Neck Surgery, Armed Forces of the Philippines Medical Center from January 1999 – December 2009 were retrospectively reviewed for data regarding sex, age, various mechanisms of injury and fractured anatomical part of the mandible. The number of fractures per site according to mechanism of injury was tabulated and prevalence ratios (95% confidence intervals) and p values were computed for the different fracture sites among the various mechanisms of injury. The probability or risk of sustaining fractures in these sites based on mechanism of injury was then computed. Results: The most fractured anatomical part of the mandible was the body (28%), followed by the parasymphysis (24%), angle (17%), symphysis (12%), ramus (8%), condyle (7%), alveolar ridge (3%) and coronoid (1%). There were associated injuries in 54% of those with mandibular fractures. In these patients, zygomaticomaxillary complex fractures occurred in 25%, head and neck abrasions and lacerations in 30%, head injuries in 28%, ocular injuries in 10%, nasal fractures in 8% and cervical spine fractures in 5%. Other injuries present were extremity trauma Evaluation of Mandibular Fractures in a Tertiary Military Hospital: A 10-year Retrospective Study Grace Naomi B. Galvan, M.D. Department of Otolaryngology Head and Neck Surgery Armed Forces of the Philippines Medical Center Correspondence: Dr. Grace Naomi B. Galvan Department of Otolaryngology Head and Neck Surgery Armed Forces of the Philippines Medical Center V. Luna Avenue, Quezon City 0840 Philippines Phone: (632) 426 2701 local 8872 E-mail: gracenaomigalvanmd@yahoo.com Reprints will not be available from the author. The author declared that this represents original material that is not being considered for publication or has not been published or accepted for publication elsewhere, in full or in part, in print or electronic media; that the manuscript has been read and approved by the author, that the requirements for authorship have been met by the author, and that the author believes that the manuscript represents honest work. Disclosures: The author signed a disclosure that there are no financial or other (including personal) relationships, intellectual passion, political or religious beliefs, and institutional affiliations that might lead to a conflict of interest. Presented at the 12th Annual North East Manila ENT Consortium Research Contest, Valdes Hall, Veteran’s Memorial Medical Center, August 18, 2010. Presented at the Descriptive Research Contest, Philippine Society of Otorhinolaryngology-Head and Neck Surgery, Glaxo Smith Kline (GSK) Bldg., Chino Roces Ave., Makati City, Philippines, October 11, 2010. PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 26 no. 1 January – June 2011 ORIGINAL ARTICLES PhiliPPine Journal of otolaryngology-head and neck Surgery 17 in 60%, thoracic trauma in 5% and abdominal trauma in 3%. Males dominated with a ratio of 99:1. Males 21 to 30 years of age sustained the most mandible fractures. Most fractures were caused by vehicular accidents (60%), followed by gunshot wounds (31%), falls (4%), violent assault (4%) and sports activities (1%). Alcohol was a contributing factor at the time of injury in 20.6% of fractures. All cases were treated by open reduction and internal fixation with plating or wiring. Conclusion: The body was the most commonly fractured anatomic region of the mandible in this series. There appeared to be a statistically significant relationship between violent assault and fractures of the ramus, but not between the other mechanisms of injury and the site of fracture. Its prevalence ratio of 3.32 (95% confidence interval: 1.13; 9.74, p value 0.039) suggests that the prevalence of fractures of the ramus among those exposed to violent assault was 3 times higher than those who were not. Keywords: mandibular fractures, etiology, maxillofacial injuries, trauma The mandible occupying a very prominent and vulnerable position on the face is the 2nd most commonly fractured bone of the face and the 10th most fractured bone in the whole body. 1 Surveys of mandible fractures have shown that the etiology varies from one country to another and even within the same country depending on the prevailing socioeconomic, cultural and environmental factors.2 However, different sources list differing anatomic regions of the mandible that are commonly fractured. The aim of this study was to determine the age group, etiology, frequency and classification of mandibular fractures seen in a tertiary military hospital, and to determine if there are significant relationships between the various mechanisms of injury and the different fracture sites. METHODS This study was a cross-sectional retrospective analysis of all mandibular fractures treated at the Armed Forces Medical Center over a 10-year period (1999-2009). Data regarding sex, age, various mechanisms of injury and fractured anatomical part of the mandible were gathered from hospital inpatient records and radiographic examinations. The specific anatomic region of the mandible fracture was determined and sites were classified according to the fractured anatomical part of the mandible as parasymphysis, body, angle, symphysis, alveolar ridge, condyle, ramus and coronoid fractures. Each fracture line was counted separately. The number of fractures per site according to mechanism of injury was tabulated, and prevalence ratios (95% confidence intervals) and p values were computed for the different fracture sites among the various mechanisms of injury using the statistical software Epi Info™ Version 3.5.3 (Centers for Disease Control, Atlanta GA, USA).The probability or risk of sustaining fractures in these sites based on mechanism of injury was then computed using the same statistical software. RESULTS A total of 328 patients aged 21 to 45 were treated for mandibular fracture during the study period. Most (282) of those treated belonged to the 21-30 year old group with a mean age of 26.98 ± 4.12 years (range 22.86 to 31.1 years). As expected in a military setting, most of the patients were male (99.1%), with females accounting for only 0.9% of the cases. Among males, the highest prevalence of mandibular fractures occurred in the 21-30 year-old group, whereas only women constituted the above 40-year-old group. The causes of mandibular fracture were varied (Table 1); however, the primary causative factor was vehicular accidents which were not work- related in 190 cases (57.9%). Combat-related injuries resulting from Table 1. Frequency of mandibular fractures according to site and mechanism of injury among the 328 patients treated at the AFP Medical Center (1999-2009) Site Vehicular accident Combat- related Fall Violent assault Sports- related Total (%) Number of fractures according to mechanism of injury Body Parasymphysis Angle Symphysis Ramus Condyle Alveolar ridge Coronoid Total 103 95 75 42 30 32 12 3 392 65 56 32 25 14 11 7 2 212 11 6 6 3 3 4 2 0 35 5 7 2 5 5 2 0 0 26 4 2 4 1 0 1 0 0 126 188 (27.77%) 166 (24.52) 119 (17.58) 76 (11.23) 52 (7.68) 50 (7.38) 21 (3.10) 5 (0.74) 677 PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 26 no. 1 January – June 2011 ORIGINAL ARTICLES 18 PhiliPPine Journal of otolaryngology-head and neck Surgery gunshots were the second most frequent cause of fracture in 102 cases (31.1%), followed by accidental falls (17 or 5.2%), violent assault (13 or 4.0%) and sports-related injuries (6 or 1.8%). On closer examination, obvious differences between sexes in the causes of fracture were readily apparent (Table 1). Males most frequently sustained fractures as the result of vehicular accidents involving the use of motorcycles (190 cases or 58.5% of the male population), followed by combat-related injuries secondary to gunshot (101 cases or 31.3% of the males). In contrast, two of the three female cases reported falls as the cause of injury. Of the 328 patients included in this study, 300 (91.50%) sustained multiple fracture sites while only 28 (8.50%) had a single fracture site. Overall, a total of 677 fractures were noted. In this study, the most commonly fractured site was the body of the mandible (188 cases or 27.77% of all fractures), followed by the parasymphysis (166 of the cases or 24.52% of all fractures). The angle, symphysis, ramus and condyle had prevalence rates of 17.58%, 11.23%, 7.68%, and 7.38%, respectively. The least commonly affected sites were the alveolar ridge and the coronoid being seen in only 21 and 5 cases, respectively. Among the various mechanisms of injury, the body of the mandible was still the most frequently affected site. Even among those patients who suffered a single fracture, the body was still noted to be the most affected area of the mandible. Among those with multiple fracture sites, the most commonly encountered combination involved the body and parasymphysis. To determine if there was a relationship between the various mechanisms of injury and the site of mandibular fracture, prevalence ratios were computed and are summarized in Table 2. It appears that violent assault and fractures of the ramus have a statistically significant relationship. Its prevalence ratio of 3.32 (95% confidence interval: 1.13; 9.74, p value 0.039) shows that the prevalence of fractures of the ramus among those exposed to violent assault was three times higher than those who were not. Associated injuries were present among 43% of those with mandible fractures. Among these patients, zygomaticomaxillary complex fractures occurred in 25%, head and neck abrasions and lacerations in 30%, head injuries in 28%, ocular injuries in 10%, nasal fractures in 8% and cervical spine fractures in 5%. Other injuries present in this group were extremity trauma in 60%, thoracic trauma in 10% and abdominal trauma in 5%. The mandible fractures were managed by open reduction and internal fixation with wires (2%) or titanium plates (98%). DISCUSSION The management of fractures to the maxillofacial complex remains a challenge for oral and maxillofacial surgeons demanding both skill and a high level of expertise. In our institution, mandibular fractures account for 45% of all maxillofacial fractures. The results of this investigation of patients with mandible fractures who were treated at the Armed Forces of the Philippines Medical Center differ from other series’ in the literature, particularly with regard to the most commonly involved anatomic region in mandible fractures. Table 3 summarizes other studies that reveal mandible fracture sites that differ from our findings.3,4,5,6 The results of this study show consistency with that of other studies with regards to the predominant age group sustaining mandibular fractures, which was the 21-30 year-old group.7 A possible explanation for the higher frequency of fractures in this group is that the second Table 2. Prevalence ratios (95% confidence intervals) and p values of different sites of mandibular fracture among the various mechanisms of injury Site of Fracture Vehicular accident Combat- related Fall Violent assault Sports- related Mechanism of Injury Body p value Parasymphysis p value Angle p value Symphysis p value Ramus p value Condyle p value Alveolar ridge p value Coronoid p value 0.88 (0.73; 1.06) 0.22 0.97 (0.78; 1.21) 0.88 1.24 (0.92; 1.67) 0.20 0.90 (0.60; 1.33) 0.69 0.99 (0.60; 1.64) 0.91 1.29 (0.76; 2.20) 0.43 0.97 (0.42; 2.23) 0.88 1.09 (0.18; 6.43) 1.00 1.16 (0.96; 1.41) 0.16 1.13 (0.90; 1.41) 0.35 0.81 (0.59; 1.13) 0.26 1.09 (0.72; 1.65) 0.81 0.82 (0.46; 1.44) 0.58 0.62 (0.33; 1.17) 0.18 1.11 (0.46; 2.66) 0.99 1.48 (0.25; 8.71) 0.65 1.14 (0.79; 1.64) 0.70 0.69 (0.36; 1.32) 0.29 0.97 (0.50; 1.88) 0.86 0.75 (0.26; 2.14) 0.77 1.12 (0.39; 3.23) 0.74 1.59 (0.65; 3.90) 0.31 1.93 (0.49; 7.60) 0.30 - 0.47 (0.16; 1.39) 0.26 1.14 (0.39; 3.32) 0.96 0.32 (0.07; 1.42) 0.14 2.07 (0.70; 6.15) 0.19 3.32 (1.13; 9.74) 0.039 1.01 (0.23; 4.42) 1.00 - - 1.49 (0.28; 8.02) 1.00 0.49 (0.09; 2.63) 0.44 3.51 (0.65; 18.89) 0.19 - - 1.11 (0.13; 9.32) 1.00 - - PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 26 no. 1 January – June 2011 ORIGINAL ARTICLES PhiliPPine Journal of otolaryngology-head and neck Surgery 19 and third decades of life are the most active, making people in these age groups vulnerable to trauma. It has also been consistently shown that the frequency of mandible fractures among males is far greater than for females.8 Previous epidemiologic studies reported road traffic accidents9,10 followed by falls as the leading cause of mandibular fractures in developing countries, others have reported assault as the main causative factor.8 The reported findings of certain aspects of mandible trauma have been widely substantiated. For example, investigators in countries such as Jordan,11 Singapore,12 Nigeria,13,14 New Zealand,15 Denmark16 and Japan17 have found that motor vehicle accidents represent the most common cause of mandible fractures in those countries, while others in Finland,18 Scotland19 and Sweden20 have reported assault as the most common etiology. In our setting, motor vehicle accidents were the single most frequent cause of mandible fractures (60%). Those suffering trauma as a result of violence were mainly males; females reported assault as the second most frequent reason for their injuries, after falls. In all too many cases, however, the clinical findings did not corroborate the history of a fall, and health care providers often suspect domestic violence. It is highly possible that a good number of females who received their injuries as a result of assault may have reported a fall as the cause. 9 Alcohol was a contributing factor at the time of injury in 21% of fractures for which this information was available in our institution. This may reflect the deleterious effects of alcohol on psychomotor skills and the lack of preventive mechanisms to respond to situational hazards.21 In Australia, alcohol involvement in mandible fractures has been reported to be as high as 41.4%, and most of the cases associated with violence (73%) were linked to alcohol abuse.22 In a study conducted in Finland, 44% of mandible fractures were associated with alcohol abuse. 22 In our study, alcohol was associated with about 20.6% of mandible fractures a proportion significantly lower than figures reported elsewhere. However, this discrepancy may also be explained by underreporting by hospital staff. The mandible fracture site depends upon the mechanism of injury, magnitude and direction of impact force, prominence of the mandible and anatomy of site. 3 Its resistance to compression is greater but tends to fracture at the site of tensile strain. 3 In addition, it is more sensitive to lateral impact especially the body and ramus. 3 In our setting, the body of the mandible was the most commonly fractured part of the mandible. Fractures of the mandible body often are unfavorable because the actions of the masseter, temporalis and medial pterygoid muscles distract the proximal segment supero-medially20 while the mylohyoid and anterior belly of the digrastic muscles displace the fractured segment posteriorly and inferiorly.23 Prevalence ratios were computed to determine if there was a relationship between the various mechanisms of injury and the site of mandibular fracture. Statistical analysis showed that even if the body was the most frequent site affected, the relationship between the various mechanisms of injury and the site of fracture were not statistically significant. However, there was a statistically significant relationship between violent assault and fractures of the ramus. Its prevalence ratio of 3.32 (95% confidence interval: 1.13; 9.74, p value 0.039) shows that the prevalence of fractures of the ramus among those exposed to violent assault was 3 times higher than those who were not. Our study has determined the body as the most common region involved in mandible fractures in the Armed Forces of the Philippines Medical Center. Mandible fractures occur in people of all ages and races, in a wide range of social settings. Their causes often reflect shifts in trauma patterns over time. It is hoped that assessments such as the one presented here will be valuable to the Armed Forces of the Philippines and military surgeons involved in planning future programs of prevention and treatment. Further studies among non-military hospitals will be valuable in extending our findings to the general population. Table 3. Comparison of the literature on the most commonly fractured part of man- dible Symphysis Parasym- physis Body Angle Ramus Condyle Coronoid Caparas et al.6 (1993) Sirimaharaj & Pyungtanasup5 (2008) Khan et al.3 (2009) Kamali & Pohchi4 (2009) This Study Galvan 2001 14% 13.24% 11.1% 16.7% 12% __ 45.3% 27.4% 23% 24% 21% 3.83% 22.2% 20.1% 28% 20% 19.51% 23.3% 23% 17% 3% 2.09% 2.3% 1.7% 8% 36% 15.68% 12.8% 15.5% 7% 2% __ 0.5% __ 1% PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 26 no. 1 January – June 2011 ORIGINAL ARTICLES 20 PhiliPPine Journal of otolaryngology-head and neck Surgery ACKNOWLEDGEMENTS The author thanks her mentor, Dr. Ma Sheila P. Jardiolin, Dr. Maribel M. Develos for statistical analysis and Dr. Michael B. Bravo for data collection. REFERENCES 1. Stanley RB. Pathogenesis and evaluation of mandibular fracture. In: Mathog RH, editor. Maxillofacial trauma. Baltimore: Williams and Wilkins; 1984. p. 136-147. 2. Adeyemo WL, Ladeinde AL, Ogunlewe MO, James O. Trends and characteristics of oral and maxillofacial injuries in Nigeria: A review of the literature. Head Face Med. 2005; 1:7-15. 3. Khan A, Salam A, Khitab U, Tariqkhan M. Pattern of mandibular fractures – a study. Pakistan Oral and Dental Journal. 2009[cited 2011 April 14]; 29(2):221-224. Available from:http://www.podj. com.pk/Dec_2009/Article-8.pdf. 4. Kamali U, Pohchi A. Mandibular fracture at HUSM: a 5-year retrospective study. Arch Orofac Sci. 2009; 4(2):33-35. 5. Sirimaharaj W, Pyungtanasup K. The epidemiology of mandibular fractures treated at Chiang Mai university hospital: a review of 198 cases. J Med Assoc Thai 2008;91(6): 868-874. 6. Caparas MB, Lim MG, Enriquez A, Jamir J, Ejercito N, Chiong A, et al., editors. Maxillofacial trauma. Basic Otolaryngology. Manila: University of the Philippines; 1993. p. 225-229. 7. Manson PN. Facial fractures. In: Mathes SJ, editor. Plastic Surgery. Vol 3. 2nd ed. Philadelphia: Saunders Elsevier; 2006. p 77-380. 8. Dibaie A, Raissian S, Ghafarzadeh S. Evaluation of maxillofacial traumatic injuries of forensic medical center of Ahwaz, Iran in 2005. Pak J Med Sci 2009; 25(1):79-82. 9. Sojat AJ, Meisami T, Sandor GK, Clokie CM. The epidemiology of mandibular fractures treated at the Toronto general hospital. A review of 246 cases. J Can Dent Assoc. 2001; 67:640-4. 10. Sigua RG, Palmiano HS, editors. Assessment of Road Safety in the ASEAN Region. Proceedings of the Eastern Asia Society for Transportation Sudies. 2005;5:2032-2045. 11. Bataineh AB. Etiology and incidence of maxillofacial fractures in the north of Jordan. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. Jul 1998;86(1):31-5. 12. Tay AG, Yeow VK, Tan BK, Sng K, Huang MH, Foo CL. A review of mandibular fractures in a craniomaxillofacial trauma centre. Ann Acad Med Singapore. Sep 1999;28(5):630-3. 13. Adekeye EO. The pattern of fractures of the facial skeleton in Kaduna, Nigeria. A survey of 1,447 cases. Oral Surg Oral Med Oral Pathol. Jun 1980;49(6):491-5. 14. Ugboko VI, Odusanya SA, Fagade OO. Maxillofacial fractures in a semi-urban Nigerian teaching hospital. A review of 442 cases. Int J Oral Maxillofac Surg. Aug 1998;27(4):286-9. 15. Adams CD, Januszkiewcz JS, Judson J. Changing patterns of severe craniomaxillofacial trauma in Auckland over eight years. Aust N Z J Surg. Jun 2000;70(6):401-4. 16. Marker P, Nielsen A, Bastian HL. Fractures of the mandibular condyle. Part 1: patterns of distribution of types and causes of fractures in 348 patients. Br J Oral Maxillofac Surg. Oct 2000;38(5):417-21. 17. Tanaka N, Tomitsuka K, Shionoya K, Andou H, Kimijima Y, Tashiro T, et al. Aetiology of maxillofacial fracture. Br J Oral Maxillofac Surg. Feb 1994;32(1):19-23. 18. Oikarinen K, Ignatius E, Silvennoinen U. Treatment of mandibular fractures in the 1980s. J Craniomaxillofac Surg. Sep 1993;21(6):245-50. 19. Adi M, Ogden GR, Chisholm DM. An analysis of mandibular fractures in Dundee, Scotland (1977 to 1985). Br J Oral Maxillofac Surg. Jun 1990;28(3):194-9. 20. Strom C, Nordenram A, Fischer K. Jaw fractures in the county of Kopparberg and Stockholm 1979-1988. A retrospective comparative study of frequency and cause with special reference to assault. Swed Dent J. 1991;15(6):285-9. 21. Dongas P, Hall GM. Mandibular fracture patterns in Tasmania, Australia. Australian Dental Journal. 2002; 47(2):131-137. 22. Savola O, Niemela O, Hillbom M. Alcohol intake and the pattern of trauma in young adults and working aged people admitted after trauma. Alcohol and Alcoholism. 2005;40:269-273. 23. Barrera JE. Mandibular Angle Fracture [updated 2010July 9; cited 2010 July 30] Available from: http://emedicine.medscape.com/article/868517-overview