A total of 35 studies were analyzed for pattern of maxillofacial injuries based on Nigeria’s geopolitical zones of Southeast, Southwest, Southsouth, Northcentral, Northeast and Northwest. No publication dealing only with the population from the North central and North eastern zones met the inclusion criteria for this study. Parameters utilized were prevalence, etiological factors and treatment. Further analysis was carried on the distribution of motorcycle-related maxillofacial injuries in the various geopolitical zones. Data analyzed were from four geopolitical zones (Southeast, Southwest, Southsouth, and Northwest. RTC represented the main cause of maxillofacial injuries among Nigerians studied. In Fig. 2, the combined risk ratio was 3.10(95% CI 2.34, 4.10) among the three geopolitical zones studied; the South west had the highest pooled prevalence of 3.59(95% CI 2.51, 5.12) followed by the Southsouth geopolitical zone with pooled prevalence of 2.88(95% CI 1.81, 4.59). Across Nigeria, RTC accounted for between 45% in the Northwest40 and 97% in the South west.23 These confirm the worrying situation of maxillofacial injuries caused by RTC in Nigeria. The World Health Organization, African Region reported that Africa had the highest fatality rate of 27.8 deaths per 100,000 inhabitants in 2010.46 However, Africa is the least motorized continent.8
MCC was responsible for a pooled prevalence of 0.44 (95% CI 0.29, 0.66) of all maxillofacial injured patients with most cases in the South west than the Southsouth and North west zones from Fig. 3. In a previous report,5 observed that MCC- related maxillofacial injuries increased significantly between 1965 and 2003 due to increasing socio-economic prosperity with deteriorating road infrastructure. In table 1, MCC was responsible for between 1.6% in the Southsouth28and 67.5% in the South west.21Causative and contributory reasons for the high rates of RTC and MCC in Nigeria have been thoroughly reviewed by Adeyemo et al.5 In the Arabian Gulf countries, RTC was mostly due to private cars as the use of motorbikes, cycles and public transport is limited.47 The differences in the prevalence of RTC and MCC in the various Nigerian geopolitical zones could be indicative of the levels of socio-economic activities in these parts that necessitate use of road transport in the various parts of the country. Nigeria needs to increase public enlightenment on the provisions of the law that involve safety among road users and implement enforcement measures to reduce the adverse impacts of road transport on maxillofacial injuries.
Assault/interpersonal violence in this study included fights, domestic violence, robbery, child battery and unrest. Figure 4 showed that the overall risk ratio of maxillofacial injuries due to assault/interpersonal violence as 0.28 (95% CI 0.19, 0.40). A previous report from Scotland had assault as being responsible for 55% of maxillofacial fractures (Adi et al., 1990) while from the Arabian Gulf countries, the proportion was 9.5%.47 Differences in various populations are attributable to social violence due to alcohol use, high unemployment rate and armed conflict, which vary in different environments.47,48In addition, this study showed the highest risk ratio for assault in the south-east (109; 95% CI, 6.9–1720) which differs from the reports by Adeyemo et al5that reported that assaults were the major cause of maxillofacial injuries from the North east geopolitical zone. This difference may be due to the unbalanced number of studies available for each geopolitical zone. Table 1 and Fig. 4 had no included study from the North east for comparison but Amole et al38reported gunshot injuries as the most common form of assault from the North west geopolitical zone of Nigeria. The rising proportion of maxillofacial injuries due to assault/interpersonal violence is reflective of the worsening state of insecurity in Nigeria especially the activities of armed groups.
The proportion of maxillofacial fractures due to falls in Saudi Arabia varies from 6.1–89.7%. Reasons for the rates include elderly patients who fracture edentulous mandible or young adults who fall forwards onto the chin, sustaining bilateral condylar fractures.47 Fig. 5 showed that among Nigerians, falls accounted for 6% of maxillofacial injuries. There were more cases from the Northwest (13%) than the South west (6%) in Fig. 5. It is suspected that some of the elderly patients from the report of Alqahtani et al47 and from the Northwest in Fig. 5 could be victims of assault- domestic violence but who are ashamed of giving the correct causative factor for socio-cultural reasons.
Eleven studies in table 1 included data on sports- related maxillofacial injuries showing an overall prevalence of 3%. The Southsouth had more sports related maxillofacial injuries than other zones reflecting greater sports awareness and practice.
The sex ratio among victims of maxillofacial injuries varies depending on socio-cultural, economic and etiological factors. In 1980, Adekeye49 reported that maxillofacial fractures from Northern Nigeria occurred in a male to female ratio of 16.9:1. In a later report from the same center, a sex ratio of 3: 1 in favour of males was given.50 This change of more than five-fold reduction in male prevalence mirrored the socio-economic and cultural changes over the study periods as RTC remained the most common etiological factor. Despite the improved socio-economic conditions in some Arabian Gulf countries, cultural factors and the prevalence of RTC are partly responsible for the male predilection giving a ratio of 6.4:1 for maxillofacial injuries.47 Countries with more gender-neutrality in social activities have male to female ratio as low as 2.5:1 for maxillofacial fracture.51 Table 1 showed the male to female ratio was between 0.8:115and 30:123 with studies that reported on multifactorial etiologies of maxillofacial injuries having male to female ratio between 2.6:111 and 30:1,23 while single etiology studies on assault/interpersonal violence reported male to female ratio between 0.8:115and 6.7:1.28 Another finding was that studies that reported more of soft15,18 than hard tissue19–21 injuries had more favorable ratio towards females. The overall male to female ratio from table 1 was 4.1:1 which is lower than 6.4:147but higher than 2.5:1 from a study in Ghana.52 It implies that the level of gender neutrality of the Nigerian population that reflects the relative participation of males and females in outdoor socio-economic activities lies between that of Arabian Gulf countries and Ghana.
Dentoalveolar fractures and maxillofacial soft tissue injuries resulting from trauma were recorded in addition to jawbone fractures in this study. While three papers16,25,27 reported on soft tissue injuries alone, there were other publications each on jawbone fractures alone or with associated soft tissue injuries. There was no unanimity in the literature on the most common maxillofacial bone fractured during trauma. The mandible is often reported as the most common fractured bone according to many workers.47,49,53 Attributable reasons were that the shape and mobility of the mandible favored its predilection to fracture during trauma; it had inadequate support from facial buttresses as compared with the maxilla and upper third of the face and its exposed position.54 In other reports, the midface consisting of the maxilla and the zygomatic complex is reported as the most fractured bone in the maxillofacial region.55,56 Cavalcanti et al54 reported that the mandible and maxilla were most common sites. In table 1, there were more mandibular than midfacial fractures. Differences in the predilection of maxillofacial bones to fracture could be from the magnitude and mechanism of injury, direction and site of impact and the availability of enhanced imaging techniques like CT to better detect fractures of the middle and upper third of the face.57 Systematic delineation of the maxillofacial region into lower, middle and upper thirds for the description of injuries would enhance description and categorization. As access to emergency health care services improve, so would survivability of severely traumatized maxillofacial patients especially in low and middle income countries. With improved survival and availability of enhanced imaging techniques like the CT in Nigeria, the proportion of mandibular to maxillary fractures could become more even.
In many countries, maxillofacial fractures are increasingly being treated using open reduction and internal fixation techniques. Earlier Nigerian workers reported the low rate of use of that treatment modality with reasons including scarcity of the equipment and materials for rigid fixation and the prohibitive cost that contributes to treatment delay.18,21 Table 1 showed that most patients were treated using closed reduction techniques such as intermaxillary fixation, suspension wiring and other conservative measures alone11–13,30,31while a few utilized it in combination with rigid fixation21,41 often with satisfactory healing of the fractures. The goal of functionally, stable fixation of facial bone fractures is a spectrum that varies based on anatomic factors and fracture morphology.58
There are relatively fewer reports on the treatment of maxillofacial soft tissue injuries as compared to fractures. In table 1, the mainstay of soft tissue treatment was debridement ± suturing, always with antibiotics and anti-tetanus prophylaxis.16,24,25 Extensive soft tissue wounds were treated using more complex modalities such as local13or distant28flaps.
Other bodily injuries coexisting with the maxillofacial injury could constitute threats to life and in some cases result in considerable morbidity. The pattern and distribution of these associated injuries varies with site/location of the maxillofacial injury, the etiology and geographical factors.56 In maxillofacial injury from non-lethal assault, associated injuries could be absent,25,36 but in RTC, it could occur in up to 74% of patients.20 In table 1, central nervous system and cervical spine involvement were the common associated injuries18,20,32,34followed by abdominal34and limb26 injuries.
Using the NOS scale adopted from Barbosa et al., 2017,8most studies selected for analysis in this review were of intermediate quality while one study was of high quality. It is also evident from table 1 that the studies utilized similar methodologies. However, the data collected showed great heterogeneity (< 90%) while comparing etiologies in the various geopolitical zones of Nigeria in Figs. 2, 3, 4, 5 and 6 while there was low heterogeneity for sports in the Southsouth region in Fig. 6. In view of the earlier finding that the included studies were of similar etiologies, the high level of heterogeneity could be indicative of disparities in sample size of the studies. The use of random- effects model in the meta-analysis was to avoid over-estimation of the final proportion of prevalence due to various etiological factors. Hence, the high level of heterogeneity should be carefully interpreted as not to de-emphasize the importance of the results of this meta-analysis. Werecommend more prospective studies of similar sample sizes especially of the RCT type (where feasible) to improve the evaluation of maxillofacial injuries in Nigeria.
Some limitations were observed in this study. Firstly, some studies had incomplete data (mean age, sex ratio, associated injuries, and details of treatment). Another is that only English language articles published between 2004 and 2019 were considered. Lastly, the unbalanced number of studies identified from different geopolitical zones in Nigeria may have skewed the results of this study towards geopolitical zones with more published articles. This also points to a dearth of published articles in certain geopolitical zones in Nigeria such as the North east and north central zones.
Nonetheless, this study presented a systematic review of maxillofacial injuries among Nigerians based on geopolitical zones which is the first of such to our knowledge. The risk ratio meta-analysis also provided a useful estimate of comparative etiological and demographic factors of maxillofacial injuries to enhance understanding and increased efforts at focused preventative activities.