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Epidemiology and Treatment of Fractures of the Zygomatic Complex
Asian J Oral Maxillofac Surg. 2008;20:59-64.
Zhang, Dong, Guan, et al
CLINICAL OBSERVATIONS
Epidemiology and Treatment of Fractures of the Zygomatic Complex Qing-Bin Zhang,1 Yao-Jun Dong,2 Jing-Bo Guan,3 Zu-Bing Li,2 Ji-Hong Zhao,2 Fu-Shen Dong1 1 Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Hebei Medical University, Shijiazhuang, 2Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, and 3Department of Radiology, No. 1 Hospital of Shijiazhuang, Hebei Medical University, Shijiazhuang, China
Abstract Objective: This descriptive analytical study evaluated the epidemiology and treatment of zygomatic fractures in China during a 10-year period, and compared findings with those in the literature. Patients and Methods: 152 patients with comparatively complete records from a total of 428 patients who had zygomatic complex fractures were reviewed, with special focus on epidemiology and treatment. Isolated fractures of the zygomatic arch were excluded. Strict medical follow-up was carried out for sourced patients. Results: There were 84 old fractures and 68 fresh ones in the patient group. Road traffic accidents were the predominant aetiological factor. The majority of patients were male, with age between 20 and 40 years. The most common feature was malar depression. Internal fixation with titanium plate was used in 123 patients, while wire fixation was done for 29 patients. 328 titanium plates were used in the rigid internal fixation group. Plates were distributed at the zygomatic-frontal suture (n = 86), zygomatic-maxillary suture and/or zygomatic crest (n = 105), zygomatic-temporal suture (n = 42), and across the fracture line (n = 95). One-site fixation was done for 21 patients, 2-site fixation for 56 patients, and 3-site fixation or higher for 75 patients. Conclusions: Results confirm that road traffic accidents remain the major cause of zygomatic fractures. Rigid internal fixation for such fractures has become more predominant and reliable with the development of improved fixation strategies. Key words: Fracture fixation, internal, Internal fixators, Surgery, Zygomatic fractures
Introduction Fractures of the zygomatic complex (ZMC) are very common in clinical practice.1 Trauma of zygomatic fractures constitutes 45% of all mid-face fractures.2 The incidence and aetiology of zygomatic fractures vary from country to country and depend on certain socioeconomic and cultural conditions. The most common cause worldwide is road traffic accidents.3 Various approaches and designs of surgical incisions have been used for the treatment of ZMC fractures.4,5 Scalp coronal incision is a common surgical approach for open reduction and rigid internal fixation of ZMC fractures in China compared with minimal incisions, especially for severely dislocated or complex fractures. The ideal surgical approach to Correspondence: Dr. Qing-Bin Zhang, Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Hebei Medical University, 383 Eastern Zhongshan Rd, Shijiazhuang City, China. Tel: (86 0311) 8626 6498; Fax: (86 0311) 8605 2791, 8605 1304; E-mail: [email protected], [email protected] © Asian 2008J Asian Oral Maxillofac Association Surg. of Oral Vol and 20, No Maxillofacial 2, 2008 Surgeons.
treat fractures of ZMC should provide enough exposure of the fractured segments, ensure less potential for further injury to facial structures, and allow for good cosmetic results. In the 1970s, introduction of miniplate osteosynthesis for treatment of zygomatic fractures revolutionised its treatment.6 Since then, fixation with intraosseous wires has decreased sharply by the year. Bone plating is regarded as the modality with the most reliable results,7 but fixation methods and sites of fixation are not systematically defined yet. Some specialists insist on 1-site fixation, while other experts prefer fixation at 2 or more sites. This study reports the epidemiology of ZMC fractures, fixation methods and sites employed when treating zygomatic fractures, and the relative popularity of rigid internal fixation and fixation sites.
Patients and Methods A total of 428 patients from various provinces of central China — Hubei, Hunan, Henan, and Jiangxi — were treated 59
Fractures of the Zygomatic Complex
at the Hospital of Stomatology, Wuhan University, Wuhan. 152 patients with complete records were chosen for the study. Patients without preoperative and postoperative radiographs and those with isolated fractures of the zygomatic arch were excluded. Data collected included age, gender, aetiology, fracture pattern, associated injuries, treatment modalities, complications, and fixation methods and sites. Patients were operated on between 1996 and 2005 and classified according to the Knight-North criterion. 8 The term ‘fresh fracture’ was used to refer to cases where the time between injury and operation was less than 15 days, while ‘old fracture’ referred to cases where fractures occurred more than 15 days before operation. Patients underwent radiological examination using plain films (orthopantomography, occipito-mental skull radiograph in Waters projection, and axial skull radiograph of the zygomatic arches) after detailed history taking and clinical examination. Computed tomography examination was not carried out for financial reasons as well as ignorance of its significance in the early period. All patients were assessed and treated by the same surgeons. Postoperative radiograph was taken approximately 10 days after the operation. Patients who could be sourced were strictly followed up regularly for up to 5 years after operation. Clinical evaluation following surgery included aesthetic symmetry of bilateral zygomatic eminences by visual assessment (frontal and lateral view and worm’s view) and palpation (lack of bony steps, especially at the zygomaticmaxillary crest), clinical restriction of functions (limited mouth opening, diplopia, etc.), oppressive bone pains, and complications. Neurosensory deficits were examined using conventional methods (cold, cotton wad, and 2-point discrimination). Other complications were observed clinically. Stability was assessed at the last visit by applying manual pressure along the lateral aspect of zygoma.
Figure 1. Fractures of the zygomatic complex (n = 152).
Results
Figure 2. Age distribution of patients with zygomatic complex fractures (n = 152).
There were 84 old fractures and 68 fresh ones in this study (Figure 1). The group included 102 male and 50 female patients. The majority of patients (81/152; 53.3%) were aged between 20 and 40 years (Figure 2). Road traffic accident was the leading aetiological factor for ZMC fractures — injuries were caused by traffic accidents (n = 76), production activity (n = 35), sports (n = 24), and assault or other factors (n = 17) [Figure 3]. As isolated fractures of the zygomatic arch were excluded from the study, fractures were categorised as type III (n = 38), type IV (n = 51), type V (n = 32), and type VI (n = 31) [Figure 4]. Commonly noticed clinical features included malar depression (n = 118), limitation of mouth opening (n = 89),diplopia (n= 24),numbness of infraorbital region (n = 31), malocclusion (n = 44), and symptoms of facial nerve injury (n = 2). 60
100
No. of patients
80
60
40
20
0 Old fractures
Fresh fractures
50 45 40
No. of patients
35 30 25 20 15 10 5 0
<10
10-20 20-30 30-40
40-50
50-60
>70
Age range (years)
Plate fixation was carried out for 123 patients, while wire fixation was done in 29 patients (Figure 5). Twenty one patients underwent 1-site fixation, 56 had 2-site fixation, and 75 patients underwent 3-site fixation or more. 328 titanium plates were used for rigid internal fixation. Plates were distributed at the zygomatic-frontal suture (n = 86), zygomatic-maxillary suture and/or zygomatic crest (n = 105), zygomatic-temporal suture (n = 42), and across the fracture line (n = 95) [Figure 6]. At a mean follow-up of 18 months, 9 of the 12 patients who developed asymmetry were found to belong to the wire fixation group. Two patients developed residual diplopia due to either a long interval between trauma and operation (n = 1) or injury to the extraocular muscles (n = 1). Five patients experienced numbness of Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
Zhang, Dong, Guan, et al
80
25
70 60 50
No. of patients
No. of patients
Rigid internal fixation Wire fixation
20
40 30 20
15
10
5
10 0
0 Road traffic Production accidents activity
Sports
Figure 5. Fixation methods used for zygomatic complex fractures from 1996 to 2005.
Figure 3. Aetiology of zygomatic complex fractures (n = 152).
120
60
100
No. of patients
50
No. of patients
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Other factors
40 30
80 60 40
20 20 10 0 0
I
II
III
IV
V
ZF
ZM
ZT
FL
Location
VI
Fracture type
Figure 4. Zygomatic complex fractures according to KnightNorth criterion.
Figure 6. Distribution of titanium plates used for bone plating (n = 328). Abbreviations: ZF = zygomatic-frontal suture; ZM = zygomatic crest/zygomatic-maxillary suture; ZT = zygomatictemporal suture; FL = fracture line.
the infraorbital region because of permanent injures to the infraorbital nerve. Ocular injuries causing blindness were seen in 2 comminuted fractures. One patient had residual
nerve palsy involving the facial nerve (Table 1). The advantages and disadvantages of bone plating and wire fixation are given in Table 2.
Table 1. Complications observed during follow-up. Complication
Follow-up (no. of patients) 1-3 months (n = 148)
Soft tissue infection Paraesthesia of infraorbital area Haemorrhage Diplopia Limited opening Asymmetry of zygoma Paresis of facial nerve
2 24 5 3 11 4 6
Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
6 months (n = 140) 0 12 0 3 3 2 5
1 year (n = 136) 0 6 0 3 2 2 3
3 years (n = 119)
5 years (n = 108)
0 5 0 2 1 2 1
0 5 0 2 1 12 1 61
Fractures of the Zygomatic Complex
Table 2. Advantages and disadvantages of wire fixation and bone plating. Method
Advantage
Wire fixation
• Accurate • Simple to perform • Possibility of fixation • Lower and affordable prices
• Experience required • Anterior and posterior stripping of sites • Possible displacement on tightening • Possible avulsion, infection, or ectropion • Antibiotics required • Increased surgical time and hospitalisation cost • Postoperative modification not possible
Plate fixation
• Fewer approaches required • Stability in 3 planes • Suitable for comminuted and old fractures • Low surgical injury • Reliable fixation
• More experience required • Longer incisions • Obvious scarring • Higher price of plate and hardware • Antibiotics required • Possible infection and ectropion • Postoperative modification not possible • Possibility of plate palpation • Possibility of plate removal
Discussion The age, gender distribution, and aetiology of zygomatic fractures are influenced by socioeconomic factors and modes of transportation.9,10 The predominance of men in the present patient population is a relatively consistent finding in most studies.11,12 The male-to-female ratio, which was 2.04:1 in the present study, was slightly lower than those reported elsewhere — 3:1 in England, France, and Jordan, and 2.85:1 in the United States.13,14 Some studies have reported that zygomatic fractures are most commonly caused by vehiclerelated accidents, whereas others indicate that assault is the most frequent cause, with only a small proportion of fractures being caused by traffic accidents.15,16 The present study shows that road traffic accidents are the leading aetiological factor for ZMC fractures in China. At present, the use of seatbelts in vehicles is not mandatory in the country, and traffic rules and regulations, although promulgated by the government, are not strictly enforced, especially in rural areas. In addition, the presence of unskilled drivers with poor professional driving experience, increasing numbers of vehicles on poor roads, and unenforced rules are thought to play important roles in the incidence of zygomatic fractures. Bicycles are commonly used in China, and bicycle accidents are known to cause zygomatic fractures. Falls are the main cause of fractures in elderly persons. In contrast, assault was identified as the most common cause of facial trauma in some western countries.17,18 This may be due to high unemployment rates and alcohol consumption, although alcohol consumption prior to driving is prohibited in most countries. In our study, assault accounted for only 8.6% (13/152) of the fractures. This is possibly due to the rapid economic growth and lower unemployment rate in China. Industrial or agricultural accidents lead to 14 zygomatic fractures in our study. Most sports injuries reported were related to football, consistent with studies in other countries.19,20 According to this study, 62
Disadvantage
traumatic severity had no association with various aetiological factors. The increasing incidence of ZMC fractures in females could be attributed to a changing workforce. Women who were earlier staying at home are now working outdoors and in high-risk occupations, thus being more exposed to traffic accidents and other aetiological factors. There are many classifications of ZMC fractures. Patients in this study were classified according to the Knight-North criterion, which is based on an analysis of plain films. This system gives a preliminary classification of zygomatic fractures, although it is not based on 3-dimensional analysis. There are 6 types of fractures — type I fractures encompass those with no significant displacement; type II fractures include only those of the arch caused by a direct blow that buckles the malar eminence inward; unrotated body fractures, medially rotated body fractures, laterally rotated body fractures, and complex fractures with additional fracture lines present across the main fragment belong to types III, IV, V, and VI, respectively. It is generally considered best to initiate treatment as early as possible for zygomatic fractures. Epidemiological studies have shown that bone plating has become increasingly common over the years with the development of fixation theories, 21,22 while wire fixation has decreased sharply concomitantly. Although wire fixation was used in the mid1990s, bone plating is widely employed now, irrespective of the kind of ZMC fracture. Twenty one patients in this study underwent 1-site fixation, 56 had 2-site fixation, and 75 patients underwent 3-site fixation or more. One-site fixation via wire fixation, which was mostly used in the early and mid-1990s, was associated with traditional Chinese ideas and the slow development of rigid internal fixation in China compared with developed countries. The results indicate that multisite fixation has become more popular with the development of fixation theory. In total, 328 titanium plates were employed Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
Zhang, Dong, Guan, et al
for rigid internal fixation in the present study, and plates were used at the zygomatic-frontal suture, zygomatic-maxillary suture and/or zygomatic crest, zygomatic-temporal suture, and across the fracture lines. The stability and exactness of reduction are still debated with regard to the number of plates and points where fixation should be undertaken.23,24 Some experts insist that 1-site fixation is adequate for zygomatic fractures, while others consider multiple-site fixations as necessary when treating zygomatic fractures.25,26 The biomechanical forces exerted on the ZMC are important considerations for the use of plate fixation in the treatment of these fractures. The tensile forces are greater at the zygomatic-frontal suture. However, the zygomaticomaxillary buttress is the area that opposes the pull of the masseter muscle. The infraorbital rim is comparatively thick and is the site of choice for plate fixation in the ZMC for some experts. However, the additional incisions required for fixation of the infraorbital rim may result in more complications. Based on previous experience,27 we propose that at least 2 locations should be fixed at the following sites for type III to VI fractures — zygomatic-frontal suture, zygomatic-temporal suture, zygomatic-maxillary suture, zygomatic crest, and fracture lines. The titanium plates should always be placed at the zygomaticomaxillary crest, which is the main stress trajectory. When dealing with severe malar depression, the zygomatic-frontal suture, which is the sub-stress trajectory, should also be fixed. For patients with rotation displacement or comminuted fractures, at least 3 locations should be fixed with titanium plates, thus providing a 3-plane fixation in space. The use of plate fixation for ZMC fractures provides many advantages, including improved stability, earlier return to function, and excellent treatment results. However, complications associated with the procedure include infection, repulsion, sensory and motor nerve injury, malunion or nonunion, and greater exposure of the fracture site resulting in obvious scarring. The disadvantages of wire fixation include infection, instability, and displacement or rotation of the fracture ends. Regular follow-up showed that of the 12 patients who developed asymmetry, 9 belonged to the wire fixation group. The reason for this could be that some rotation or displacement of the fracture ends could not always be avoided, and the inclusion of small but occasionally important fragments could not always be achieved by this technique. The interval between trauma and operation was too long for 1 of the 2 patients who developed residual diplopia; the other had injuries to the extraocular muscles. Of the 5 patients who experienced numbness of the infraorbital region due to permanent injuries of the infraorbital nerve, 3 had rigid internal fixation. One patient had residual nerve palsy involving the facial nerve. These follow-up results indicate certain difficulties in the treatment Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
of comminuted and old zygomatic fractures. Some of the problem areas entail deciding the precise location of the dislocated bone in order to achieve facial symmetry following surgery, especially during follow-up, and reconstructing the bone defect, if any. Further studies and research addressing these issues are recommended.
References 1.
Zachariades N, Mezitis M, Anagnostopoulos D. Changing trends in the treatment of zygomaticomaxillary complex fractures: a 12-year evaluation of methods used. J Oral Maxillofac Surg. 1998;56:1152-7; discussion 1156-7.
2.
Manson PN, Crawley WA, Yaremchuk MJ, Rochman GM, Hoopes JE, French JH Jr. Midfacial fractures: advantages of immediate extended open reduction and bone grafting. Plast Reconstr Surg. 1985;76: 1-12.
3.
Telfer MR, Jones GM, Shepherd JP. Trends in the aetiology of maxillofacial fractures in the United Kingdom (1977-1987). Br J Oral Maxillofac Surg. 1991;29:250-5.
4.
Burm JS, Oh SJ. Prevention and treatment of wide scar and alopecia in the scalp: wedge excision and double relaxation suture. Plast Reconstr Surg. 1999;103:1143-9.
5.
Zhang QB, Dong YJ, Li ZB, Zhao JH. Coronal incision for treating zygomatic complex fractures. J Craniomaxillofac Surg. 2006;34: 182-5.
6.
Michelet FX, Deymes J, Dessus B. Osteosynthesis with miniaturized screwed plates in maxillo-facial surgery. J Maxillofac Surg. 1973;1: 79-84.
7.
Czerwinski M, Martin M, Lee C. Quantitative comparison of open reduction and internal fixation versus the Gillies method in the treatment of orbitozygomatic complex fractures. Plast Reconstr Surg. 2005;115:1848-54; discussion 1855-7.
8.
Knight JS, Night JF. The classification of malar fractures: an analysis of displacement as a guide to treatment. Br J Plast Surg. 1961;13: 325-9.
9.
Tanaka N, Tomitsuka K, Shionoya K, Andou H, Kimijima Y, Tashiro T, et al. Aetiology of maxillofacial fracture. Br J Oral Maxillofac Surg. 1994;32:19-23.
10. Fasola AO, Obiechina AE, Arotiba JT. Incidence and pattern of maxillofacial fractures in the elderly. Int J Oral Maxillofacial Surg. 2003; 32:206-8. 11. Rabi AG, Khateery SM. Maxillofacial trauma in Al Madina region of Saudi Arabia: a 5-year retrospective study. Asian J Oral Maxillofac Surg. 2002;14:10-4. 12. Brasileiro BF, Passeri LA. Epidemiological analysis of maxillofacial fractures in Brazil: a 5-year prospective study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006;102:28-34. 13. Thomson WM, Stephenson S, Kieser JA, Langley JD. Dental and maxillofacial injuries among older New Zealanders during the 1990s. Int J Oral Maxillofacial Surg. 2003;32:201-5. 14. Gomes PP, Passeri LA, Barbosa JR. A 5-year retrospective study of zygomatico-orbital complex and zygomatic arch fractures in Sao Paulo State, Brazil. J Oral Maxillofac Surg. 2006;64:63-7.
63
Fractures of the Zygomatic Complex 15. Bataineh AB. Etiology and incidence of maxillofacial fractures in north of Jordan. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1998; 86:31-5. 16. Brook IM, Wood N. Aetiology and incidence of facial fractures in adults. Int J Oral Surg. 1983;12:293-8. 17. Fasola AO, Nyako EA, Obiechina AE, Arotiba JT. Trends in the characteristics of maxillofacial fractures in Nigeria. J Oral Maxillofac Surg. 2003;61:1140-3. 18. Motamedi MH. An assessment of maxillofacial fractures: a 5-year study of 237 patients. J Oral Maxillofac Surg. 2003;61:61-4. 19. Gassner R, Tuli T, Hächl O, Rudisch A, Ulmer H. Cranio-maxillofacial trauma: a 10 year review of 9,543 cases with 21,067 injuries. J Craniomaxillofac Surg. 2003;31:51-61. 20. Cerulli G, Carboni A, Mercurio A, Perugini M, Becelli R. Soccer-related craniomaxillofacial injuries. J Craniofac Surg. 2002;13:627-30. 21. O’Sullivan ST, Panchal J, O’Donoghue JM, Beausang ES, O’Shaughnessy M, O’Connor TP. Is there still a role for traditional
64
methods in the management of fractures of the zygomatic complex? Injury. 1998;29:413-5. 22. Mavili ME, Tunçbilek G. Treatment of noncomminuted zygoma fractures with percutaneous reduction and rigid external devices. J Craniofac Surg. 2005;16:829-33. 23. Smyth AG. A modified miniplate for use in malar complex fractures. Br J Oral Maxillofac Surg. 1995;33:169-70. 24. Davidson J, Nickerson D, Nickerson B. Zygomatic fractures: comparison of methods of internal fixation. Plast Reconstr Surg. 1990;86:25-32. 25. Holmes KD, Matthews BL. Three-point alignment of zygoma fractures with miniplate fixation. Arch Otolaryngol Head Neck Surg. 1989;115: 961-3. 26. Tarabichi M. Transsinus reduction and one-point fixation of malar fractures. Arch Otolaryngol Head Neck Surg. 1994;120:620-5. 27. Zhang QB, Dong YJ, Li ZB, Zhao JH, Dong FS. Clinical analysis of fixation methods and sites in treatment of zygomatic complex fractures [article in Chinese]. J Pract Stomatol. 2007;23:696-8.
Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
Zhang, Dong, Guan, et al
CLINICAL OBSERVATIONS
Epidemiology and Treatment of Fractures of the Zygomatic Complex Qing-Bin Zhang,1 Yao-Jun Dong,2 Jing-Bo Guan,3 Zu-Bing Li,2 Ji-Hong Zhao,2 Fu-Shen Dong1 1 Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Hebei Medical University, Shijiazhuang, 2Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, and 3Department of Radiology, No. 1 Hospital of Shijiazhuang, Hebei Medical University, Shijiazhuang, China
Abstract Objective: This descriptive analytical study evaluated the epidemiology and treatment of zygomatic fractures in China during a 10-year period, and compared findings with those in the literature. Patients and Methods: 152 patients with comparatively complete records from a total of 428 patients who had zygomatic complex fractures were reviewed, with special focus on epidemiology and treatment. Isolated fractures of the zygomatic arch were excluded. Strict medical follow-up was carried out for sourced patients. Results: There were 84 old fractures and 68 fresh ones in the patient group. Road traffic accidents were the predominant aetiological factor. The majority of patients were male, with age between 20 and 40 years. The most common feature was malar depression. Internal fixation with titanium plate was used in 123 patients, while wire fixation was done for 29 patients. 328 titanium plates were used in the rigid internal fixation group. Plates were distributed at the zygomatic-frontal suture (n = 86), zygomatic-maxillary suture and/or zygomatic crest (n = 105), zygomatic-temporal suture (n = 42), and across the fracture line (n = 95). One-site fixation was done for 21 patients, 2-site fixation for 56 patients, and 3-site fixation or higher for 75 patients. Conclusions: Results confirm that road traffic accidents remain the major cause of zygomatic fractures. Rigid internal fixation for such fractures has become more predominant and reliable with the development of improved fixation strategies. Key words: Fracture fixation, internal, Internal fixators, Surgery, Zygomatic fractures
Introduction Fractures of the zygomatic complex (ZMC) are very common in clinical practice.1 Trauma of zygomatic fractures constitutes 45% of all mid-face fractures.2 The incidence and aetiology of zygomatic fractures vary from country to country and depend on certain socioeconomic and cultural conditions. The most common cause worldwide is road traffic accidents.3 Various approaches and designs of surgical incisions have been used for the treatment of ZMC fractures.4,5 Scalp coronal incision is a common surgical approach for open reduction and rigid internal fixation of ZMC fractures in China compared with minimal incisions, especially for severely dislocated or complex fractures. The ideal surgical approach to Correspondence: Dr. Qing-Bin Zhang, Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Hebei Medical University, 383 Eastern Zhongshan Rd, Shijiazhuang City, China. Tel: (86 0311) 8626 6498; Fax: (86 0311) 8605 2791, 8605 1304; E-mail: [email protected], [email protected] © Asian 2008J Asian Oral Maxillofac Association Surg. of Oral Vol and 20, No Maxillofacial 2, 2008 Surgeons.
treat fractures of ZMC should provide enough exposure of the fractured segments, ensure less potential for further injury to facial structures, and allow for good cosmetic results. In the 1970s, introduction of miniplate osteosynthesis for treatment of zygomatic fractures revolutionised its treatment.6 Since then, fixation with intraosseous wires has decreased sharply by the year. Bone plating is regarded as the modality with the most reliable results,7 but fixation methods and sites of fixation are not systematically defined yet. Some specialists insist on 1-site fixation, while other experts prefer fixation at 2 or more sites. This study reports the epidemiology of ZMC fractures, fixation methods and sites employed when treating zygomatic fractures, and the relative popularity of rigid internal fixation and fixation sites.
Patients and Methods A total of 428 patients from various provinces of central China — Hubei, Hunan, Henan, and Jiangxi — were treated 59
Fractures of the Zygomatic Complex
at the Hospital of Stomatology, Wuhan University, Wuhan. 152 patients with complete records were chosen for the study. Patients without preoperative and postoperative radiographs and those with isolated fractures of the zygomatic arch were excluded. Data collected included age, gender, aetiology, fracture pattern, associated injuries, treatment modalities, complications, and fixation methods and sites. Patients were operated on between 1996 and 2005 and classified according to the Knight-North criterion. 8 The term ‘fresh fracture’ was used to refer to cases where the time between injury and operation was less than 15 days, while ‘old fracture’ referred to cases where fractures occurred more than 15 days before operation. Patients underwent radiological examination using plain films (orthopantomography, occipito-mental skull radiograph in Waters projection, and axial skull radiograph of the zygomatic arches) after detailed history taking and clinical examination. Computed tomography examination was not carried out for financial reasons as well as ignorance of its significance in the early period. All patients were assessed and treated by the same surgeons. Postoperative radiograph was taken approximately 10 days after the operation. Patients who could be sourced were strictly followed up regularly for up to 5 years after operation. Clinical evaluation following surgery included aesthetic symmetry of bilateral zygomatic eminences by visual assessment (frontal and lateral view and worm’s view) and palpation (lack of bony steps, especially at the zygomaticmaxillary crest), clinical restriction of functions (limited mouth opening, diplopia, etc.), oppressive bone pains, and complications. Neurosensory deficits were examined using conventional methods (cold, cotton wad, and 2-point discrimination). Other complications were observed clinically. Stability was assessed at the last visit by applying manual pressure along the lateral aspect of zygoma.
Figure 1. Fractures of the zygomatic complex (n = 152).
Results
Figure 2. Age distribution of patients with zygomatic complex fractures (n = 152).
There were 84 old fractures and 68 fresh ones in this study (Figure 1). The group included 102 male and 50 female patients. The majority of patients (81/152; 53.3%) were aged between 20 and 40 years (Figure 2). Road traffic accident was the leading aetiological factor for ZMC fractures — injuries were caused by traffic accidents (n = 76), production activity (n = 35), sports (n = 24), and assault or other factors (n = 17) [Figure 3]. As isolated fractures of the zygomatic arch were excluded from the study, fractures were categorised as type III (n = 38), type IV (n = 51), type V (n = 32), and type VI (n = 31) [Figure 4]. Commonly noticed clinical features included malar depression (n = 118), limitation of mouth opening (n = 89),diplopia (n= 24),numbness of infraorbital region (n = 31), malocclusion (n = 44), and symptoms of facial nerve injury (n = 2). 60
100
No. of patients
80
60
40
20
0 Old fractures
Fresh fractures
50 45 40
No. of patients
35 30 25 20 15 10 5 0
<10
10-20 20-30 30-40
40-50
50-60
>70
Age range (years)
Plate fixation was carried out for 123 patients, while wire fixation was done in 29 patients (Figure 5). Twenty one patients underwent 1-site fixation, 56 had 2-site fixation, and 75 patients underwent 3-site fixation or more. 328 titanium plates were used for rigid internal fixation. Plates were distributed at the zygomatic-frontal suture (n = 86), zygomatic-maxillary suture and/or zygomatic crest (n = 105), zygomatic-temporal suture (n = 42), and across the fracture line (n = 95) [Figure 6]. At a mean follow-up of 18 months, 9 of the 12 patients who developed asymmetry were found to belong to the wire fixation group. Two patients developed residual diplopia due to either a long interval between trauma and operation (n = 1) or injury to the extraocular muscles (n = 1). Five patients experienced numbness of Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
Zhang, Dong, Guan, et al
80
25
70 60 50
No. of patients
No. of patients
Rigid internal fixation Wire fixation
20
40 30 20
15
10
5
10 0
0 Road traffic Production accidents activity
Sports
Figure 5. Fixation methods used for zygomatic complex fractures from 1996 to 2005.
Figure 3. Aetiology of zygomatic complex fractures (n = 152).
120
60
100
No. of patients
50
No. of patients
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Other factors
40 30
80 60 40
20 20 10 0 0
I
II
III
IV
V
ZF
ZM
ZT
FL
Location
VI
Fracture type
Figure 4. Zygomatic complex fractures according to KnightNorth criterion.
Figure 6. Distribution of titanium plates used for bone plating (n = 328). Abbreviations: ZF = zygomatic-frontal suture; ZM = zygomatic crest/zygomatic-maxillary suture; ZT = zygomatictemporal suture; FL = fracture line.
the infraorbital region because of permanent injures to the infraorbital nerve. Ocular injuries causing blindness were seen in 2 comminuted fractures. One patient had residual
nerve palsy involving the facial nerve (Table 1). The advantages and disadvantages of bone plating and wire fixation are given in Table 2.
Table 1. Complications observed during follow-up. Complication
Follow-up (no. of patients) 1-3 months (n = 148)
Soft tissue infection Paraesthesia of infraorbital area Haemorrhage Diplopia Limited opening Asymmetry of zygoma Paresis of facial nerve
2 24 5 3 11 4 6
Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
6 months (n = 140) 0 12 0 3 3 2 5
1 year (n = 136) 0 6 0 3 2 2 3
3 years (n = 119)
5 years (n = 108)
0 5 0 2 1 2 1
0 5 0 2 1 12 1 61
Fractures of the Zygomatic Complex
Table 2. Advantages and disadvantages of wire fixation and bone plating. Method
Advantage
Wire fixation
• Accurate • Simple to perform • Possibility of fixation • Lower and affordable prices
• Experience required • Anterior and posterior stripping of sites • Possible displacement on tightening • Possible avulsion, infection, or ectropion • Antibiotics required • Increased surgical time and hospitalisation cost • Postoperative modification not possible
Plate fixation
• Fewer approaches required • Stability in 3 planes • Suitable for comminuted and old fractures • Low surgical injury • Reliable fixation
• More experience required • Longer incisions • Obvious scarring • Higher price of plate and hardware • Antibiotics required • Possible infection and ectropion • Postoperative modification not possible • Possibility of plate palpation • Possibility of plate removal
Discussion The age, gender distribution, and aetiology of zygomatic fractures are influenced by socioeconomic factors and modes of transportation.9,10 The predominance of men in the present patient population is a relatively consistent finding in most studies.11,12 The male-to-female ratio, which was 2.04:1 in the present study, was slightly lower than those reported elsewhere — 3:1 in England, France, and Jordan, and 2.85:1 in the United States.13,14 Some studies have reported that zygomatic fractures are most commonly caused by vehiclerelated accidents, whereas others indicate that assault is the most frequent cause, with only a small proportion of fractures being caused by traffic accidents.15,16 The present study shows that road traffic accidents are the leading aetiological factor for ZMC fractures in China. At present, the use of seatbelts in vehicles is not mandatory in the country, and traffic rules and regulations, although promulgated by the government, are not strictly enforced, especially in rural areas. In addition, the presence of unskilled drivers with poor professional driving experience, increasing numbers of vehicles on poor roads, and unenforced rules are thought to play important roles in the incidence of zygomatic fractures. Bicycles are commonly used in China, and bicycle accidents are known to cause zygomatic fractures. Falls are the main cause of fractures in elderly persons. In contrast, assault was identified as the most common cause of facial trauma in some western countries.17,18 This may be due to high unemployment rates and alcohol consumption, although alcohol consumption prior to driving is prohibited in most countries. In our study, assault accounted for only 8.6% (13/152) of the fractures. This is possibly due to the rapid economic growth and lower unemployment rate in China. Industrial or agricultural accidents lead to 14 zygomatic fractures in our study. Most sports injuries reported were related to football, consistent with studies in other countries.19,20 According to this study, 62
Disadvantage
traumatic severity had no association with various aetiological factors. The increasing incidence of ZMC fractures in females could be attributed to a changing workforce. Women who were earlier staying at home are now working outdoors and in high-risk occupations, thus being more exposed to traffic accidents and other aetiological factors. There are many classifications of ZMC fractures. Patients in this study were classified according to the Knight-North criterion, which is based on an analysis of plain films. This system gives a preliminary classification of zygomatic fractures, although it is not based on 3-dimensional analysis. There are 6 types of fractures — type I fractures encompass those with no significant displacement; type II fractures include only those of the arch caused by a direct blow that buckles the malar eminence inward; unrotated body fractures, medially rotated body fractures, laterally rotated body fractures, and complex fractures with additional fracture lines present across the main fragment belong to types III, IV, V, and VI, respectively. It is generally considered best to initiate treatment as early as possible for zygomatic fractures. Epidemiological studies have shown that bone plating has become increasingly common over the years with the development of fixation theories, 21,22 while wire fixation has decreased sharply concomitantly. Although wire fixation was used in the mid1990s, bone plating is widely employed now, irrespective of the kind of ZMC fracture. Twenty one patients in this study underwent 1-site fixation, 56 had 2-site fixation, and 75 patients underwent 3-site fixation or more. One-site fixation via wire fixation, which was mostly used in the early and mid-1990s, was associated with traditional Chinese ideas and the slow development of rigid internal fixation in China compared with developed countries. The results indicate that multisite fixation has become more popular with the development of fixation theory. In total, 328 titanium plates were employed Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
Zhang, Dong, Guan, et al
for rigid internal fixation in the present study, and plates were used at the zygomatic-frontal suture, zygomatic-maxillary suture and/or zygomatic crest, zygomatic-temporal suture, and across the fracture lines. The stability and exactness of reduction are still debated with regard to the number of plates and points where fixation should be undertaken.23,24 Some experts insist that 1-site fixation is adequate for zygomatic fractures, while others consider multiple-site fixations as necessary when treating zygomatic fractures.25,26 The biomechanical forces exerted on the ZMC are important considerations for the use of plate fixation in the treatment of these fractures. The tensile forces are greater at the zygomatic-frontal suture. However, the zygomaticomaxillary buttress is the area that opposes the pull of the masseter muscle. The infraorbital rim is comparatively thick and is the site of choice for plate fixation in the ZMC for some experts. However, the additional incisions required for fixation of the infraorbital rim may result in more complications. Based on previous experience,27 we propose that at least 2 locations should be fixed at the following sites for type III to VI fractures — zygomatic-frontal suture, zygomatic-temporal suture, zygomatic-maxillary suture, zygomatic crest, and fracture lines. The titanium plates should always be placed at the zygomaticomaxillary crest, which is the main stress trajectory. When dealing with severe malar depression, the zygomatic-frontal suture, which is the sub-stress trajectory, should also be fixed. For patients with rotation displacement or comminuted fractures, at least 3 locations should be fixed with titanium plates, thus providing a 3-plane fixation in space. The use of plate fixation for ZMC fractures provides many advantages, including improved stability, earlier return to function, and excellent treatment results. However, complications associated with the procedure include infection, repulsion, sensory and motor nerve injury, malunion or nonunion, and greater exposure of the fracture site resulting in obvious scarring. The disadvantages of wire fixation include infection, instability, and displacement or rotation of the fracture ends. Regular follow-up showed that of the 12 patients who developed asymmetry, 9 belonged to the wire fixation group. The reason for this could be that some rotation or displacement of the fracture ends could not always be avoided, and the inclusion of small but occasionally important fragments could not always be achieved by this technique. The interval between trauma and operation was too long for 1 of the 2 patients who developed residual diplopia; the other had injuries to the extraocular muscles. Of the 5 patients who experienced numbness of the infraorbital region due to permanent injuries of the infraorbital nerve, 3 had rigid internal fixation. One patient had residual nerve palsy involving the facial nerve. These follow-up results indicate certain difficulties in the treatment Asian J Oral Maxillofac Surg. Vol 20, No 2, 2008
of comminuted and old zygomatic fractures. Some of the problem areas entail deciding the precise location of the dislocated bone in order to achieve facial symmetry following surgery, especially during follow-up, and reconstructing the bone defect, if any. Further studies and research addressing these issues are recommended.
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