Maxillofacial fractures following airbag deployment

Facial Protection to Prevent Facial Trauma and Allow for Optimal Protection after Facial Fracture Repair

Facial skeletal fractures continue to affect humankind, and many methods to alleviate and prevent the injuries outright have been sought after. Prevention is desired, but the implementation and general compliance may contribute to missed opportunities to decrease the burden of facial skeletal trauma. In this article, we explore the preventative as well as postoperative options for the protection of the facial skeleton.

Analysis of the Changing Patterns of Midface Fractures Using 3D Computed Tomography: An Observational Study

This article aims to analyze the changing Le Fort fracture patterns using computed tomography (CT) scans with three-dimensional (3D) reconstruction. A prospective observational study was conducted on 60 patients with midface trauma, who had reported to MS Ramaiah Group of Hospitals, Bangalore, between January 2015 and October 2016. CT scans using 1.6 mm axial, sagittal, coronal sections were taken and their 3D reconstruction was made. The images were studied and compared with the standard Le Fort lines. The deviations from the classical Le Fort lines were analyzed and recorded. A note was also made of any additional fixation that was required for these deviations. Descriptive analysis was done and the results expressed in numbers and percentages. Study revealed that the most common cause for the midface fractures was found to be road traffic accidents (81.7%) with a male preponderance (88.3%) and peak incidence in 21 to 30 years of age (40%). Among the 60 patients, 18 (30%) patients had fracture patterns similar to the ideal Le Fort lines, 4 (6.6%) had a combination of Le Fort patterns, and 38 (66.3%) patients had deviations seen from the ideal Le Fort lines. Four types of deviations were recorded, namely, D1(60%), D2(5.4%), D3(10.9%), and D4(23.6%). It was observed that D1 and D3 required additional fixation. Majority of the cases presented as a deviation from ideal Le Fort fractures. CT was a valuable tool in the assessment of these fracture patterns. Deviations, if any, could be better analyzed using the 3D reconstruction images. Proper diagnosis and detection of these deviations make the planning for fixation easier. Repetition of these deviations could propose a newer or modified classification system for Le Fort fractures.

Influence of different shoulder-elbow configurations on steering precision and steering velocity in automotive context

Ergonomic design requirements are needed to develop optimum vehicle interfaces for the driver. The majority of the current specifications consider only anthropometric conditions and subjective evaluations of comfort. This paper examines specific biomechanical aspects to improve the current ergonomic requirements. Therefore, a research which involved 40 subjects was carried out to obtain more knowledge in the field of steering movement while driving a car. Five different shoulder-elbow joint configurations were analyzed using a driving simulator to find optimum posture for driving in respect of steering precision and steering velocity. Therefore, a 20 s precision test and a test to assess maximum steering velocity over a range of 90° steering motion have been conducted. The results show that driving precision, as well as maximum steering velocity, are significantly increased in mid-positions (elbow angles of 95° and 120°) compared to more flexed (70°) or extended (145° and 160°) postures. We conclude that driver safety can be enhanced by implementing these data in the automotive design process because faster and highly precise steering can be important during evasive actions and in accident situations. In addition, subjective comfort rating, analyzed with questionnaires, confirmed experimental results.

Need for airbag and seatbelt to reduce orbital injuries from steering wheel knob

The aims of this study are to report a blowout fracture of the orbital floor and medial wall caused by being struck by a steering wheel knob of an automobile and to discuss the use of airbags and seatbelts as a preventive measure for orbital injuries. A 58-year-old man was struck in the left eye by a steering wheel. His car hit a telephone pole, and he had a frontal collision injury. In this frontal impact, his left eye was hit by a Brodie knob attached to the steering wheel. At the time of injury, the speed of the car was about 65 km/h. He was not wearing a seatbelt, and the airbag had not deployed. Swelling and ecchymosis were observed at the left periorbital area, and he had diplopia on a left-side gaze. A CT revealed fractures in the medial and inferior wall of the left orbit. Entrapped soft tissues were reduced, and the medial wall and floor were reconstructed with a resorbable sheet. His diplopia disappeared 12 days after surgery. To prevent the injury from the steering wheel knob, an airbag should be installed in any vehicle, which has a steering wheel knob. Legislation mandating the use of airbags as well as seatbelts in vehicles with attached steering wheel knobs should be made.

Assessment of changing patterns of Le fort fracture lines using computed tomography scan: an observational study

OBJECTIVES

To assess the changing mid-face fracture patterns using a computed tomography scan.

METHODOLOGY

Fifty patients with mid-face trauma requiring open reduction and fixation were studied using 1.6 mm axial, sagittal, coronal and 3D images. Images were evaluated clinically, intra-operatively and finally were compared with standard Le Fort lines. Results. The male population dominated the female at a ratio of 11.5:1. The majority of the mid-face fractures were seen in the age group of 21-30 years. Road traffic accident (78%) was the major etiological factor followed by work-related accidents (12%) and assaults (10%). The CT scan analysis included categorizing the patients into three groups: (1) Fracture patterns resembling Le Fort lines (24%); (2) Fracture patterns partially resembling Le Fort lines (56%); and (3) Fracture patterns that do not resemble Le Fort lines (20%).

CONCLUSION

With the change in the velocity of wounding object, there is a change in the mid-face fracture patterns. The majority of the cases present as a variant of classical Le Fort fractures. Computed tomography is a valuable diagnostic tool in assessing the fractures of the mid-face. 2D images are more sensitive than 3D images. However, both the images are required in delivery of an optimal treatment plan.

Trigeminal Nerve Injury Following Accidental Airbag Deployment and Assessment with Quantitative Sensory Testing

High velocity motor vehicle accidents are associated with an increase in mortality rates and a significant number of facial injuries. Accidental deployment of airbags and the associated release of hot gases can result in both thermal and mechanical injuries. The more commonly reported maxillofacial injuries include temporomandibular joint fractures and dislocations, dental trauma, facial nerve paralysis, and other orofacial pain complaints. The following case report describes a patient with facial trauma from the accidental deployment of an airbag resulting in complaints consistent with a neurological injury for which quantitative sensory testing was used in confirming the diagnosis.

Vehicle occupant restraint systems impact on eye injuries: a review

Vehicle occupant trauma to the eyes and associated facial structures has evolved rapidly in conjunction with safety-oriented vehicle design, including restraint systems. Trends vary worldwide with culture, personal factors, vehicle safety equipment, and the traffic environment-including physical, legislative, and enforcement. Wearing safety belts is essential to occupant protection. Airbags were designed as a supplement to protect the head from hard surfaces in frontal crashes, not as a primary countermeasure. Even where vehicle fleets are new with high airbag prevalence, but safety culture and knowledge of restraints is less than robust, injury attributable to not wearing seatbelts is frequent, especially in countries where high-powered vehicles are prevalent. Upper bodies of rapidly forward-moving unrestrained occupants collide with rearward-accelerating airbags. Airbag deployment produces injuries such as corneal abrasions, alkali burns, and the effects of globe compression.

Pattern of craniofacial injuries in patients admitted to Tanta University Hospital--Egypt

The goal of this work was to determine the craniofacial injury patterns in hospitalized patients to facilitate the awareness, by identifying, describing and quantifying trauma for use in planning and evaluation of preventive programs. Two-hundred and fifty five patients with craniofacial injuries were registered at the department of neurosurgery in Tanta University Hospital. Data were collected including age, gender, medical history, cause of injury and type of injury, location and frequency of soft tissue injuries, skull fractures, facial bone fractures, brain injuries and concomitant injuries, patient symptoms, clinical signs and the radiological findings. The most common causes of craniofacial injuries were road traffic accidents, followed by activity of daily life and assaults. Gender distribution showed that, males were at higher risk than females with a ratio of 5.5/1. In total of skull fractures, 47.84% were fissure fracture and 24.31% were depressed fractures. In total of brain injuries, 7.06% for concussion, 4.71% for contusion, 10.98% for brain laceration, 14.12% for pneumocephalus and 36.47% for brain edema. Regression analysis revealed increased risk for skull fractures and brain injuries in traffic accidents were 84.78%, 94.20%, respectively, and 59.14%, 50.54% in activity of daily life, but the probability of soft tissue injuries increase in traffic accident and violence.

Are airbags effective in decreasing trauma in auto accidents?

Multiple studies have addressed the effect of airbags on injury and mortality after motor vehicle collision with discrepant results (Table 1). Although large, population-based studies have minimized the protective effect of airbags, the most recent studies examining airbags have shown a decrease in injury and death, with the greatest protective effect seen when they are used in conjunction with seatbelts. Optimal restraint use is also associated with a decrease in infectious morbidity and hospital resource utilization. The widespread use of seatbelts and airbags will continue to save lives and decrease morbidity after motor vehicle collision.

Impact of airbags on a Level I trauma center: injury patterns, infectious morbidity, and hospital costs

BACKGROUND

To date, no study has evaluated the potential impact of supplemental restraint use on resource use at a Level I trauma center. We hypothesized that airbag use would be related to decreased injury severity of motor vehicle collision survivors admitted to a Level I trauma center, leading to a decrease in infectious morbidity and hospital resource use.

STUDY DESIGN

Using the trauma registry, motor vehicle collision victims admitted during an 11-year period were identified. Restraint groups were defined as unrestrained (reference group), seatbelt only, airbag only, or airbag and seatbelt. Multivariable logistic regression was used to determine the relationship between restraint type and injury patterns. Other outcomes measured included prevalence of ventilator-associated pneumonia and bacteremia, hospital length of stay, days in the ICU, and hospital mortality.

RESULTS

A total of 14,390 patients (unrestrained, n = 7,881; airbag only, n = 692; seatbelt only, n = 4,909; airbag and seatbelt, n = 908) had restraint data available. Both airbag and seatbelt use were associated with a substantial reduction in injury to the brain, face, cervical spine, thorax, and abdomen. The largest reduction occurred when these restraints were used in combination. The only injury associated with airbag deployment was extremity fractures. Compared with unrestrained persons, any restraint use was associated with substantially reduced injury severity, significant infectious morbidity, and resource use.

CONCLUSIONS

Airbags are associated with reduced in-hospital mortality. Airbags are also associated with decreased injury severity, substantial infectious morbidity, and resource use. Cost savings from reduced resource use associated with supplemental restraints could be tremendous.

MOC-PSSM CME article: Zygomatic fractures

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand the common signs, symptoms, and treatment options for zygomatic fractures. 2. Answer basic questions on therapy for zygomatic fractures.

SUMMARY

This maintenance of certification article on zygomatic fractures attempts to review the current approaches to the treatment of these fractures. Although the article does not deal with extended approaches to treatment, it does in a general sense present the preoperative, intraoperative, and postoperative thinking for the plastic surgeon approaching these patients in general practice. A further in-depth review can be obtained through the references at the end of the article.

Occipital condyle fracture: An unusual airbag injury

The installation of airbags in motor vehicles, in association with the use of seat belts, has reduced the incidence of head injuries, as well as significantly decreasing morbidity and mortality in motor vehicle accidents. Nevertheless, the literature on the subject increasingly refers to lesions related to airbag deployment. These are usually minor, but in certain circumstances, severe and fatal injuries can result. This is a case report of serious injury due to airbag deployment, involving a restrained driver who suffered occipital condylar injury when his airbag deployed in a frontal collision. The range of airbag associated injuries is reported and predisposing factors, such as the probable proximity to the airbag housing, is discussed.

Air Bag-Induced Orbital Blow-Out Fractures

RATIONALE

Although air bags have decreased the risk of serious injury from motor vehicle crashes, their deployment is not innocuous and can result in injury. The force of the deploying air bag can cause orbital blow-out fractures. We investigated the circumstances that predispose a crash occupant to this particular injury.

STUDY DESIGN

The authors conducted a case series.

METHODS

A total of 150 orbital fractures occurred among 2,739 occupants in crashes included in the Crash Injury Research and Engineering Network (CIREN) database from January 1997 to July 2005. Ten orbital blow-out fractures attributed solely to air bag deployment were extracted and four reported in depth. Occupant, vehicle, and crash characteristics were reviewed for predisposing similarities and to investigate the mechanism of injury.

RESULTS

All crashes had air bag deployment and a frontal or near-frontal principle direction of force. Nine of 10 injured occupants were positioned within the air bag's deployment zone at the time of impact as a result of a forward seat track position, falling asleep at the wheel, being unrestrained, or having decelerated before impact. Six of 10 occupants experiencing orbital blow-out fractures were of shorter than average height. Based on rigorous crash reconstructions, the orbital blow-out injuries were felt to be causally related to air bag deployment.

CONCLUSION

Air bag deployment may result in orbital blow-out fractures. Occupants positioned in close proximity to the air bag during its deployment phase appear to be at increased risk for orbital blow-out fractures.

Finite element modeling of the head skeleton with a new local quantitative assessment approach

The present study was undertaken to build a finite element model of the head skeleton and to perform a new assessment approach in order to validate it. The application fields for such an improved model are injury risk prediction as well as surgical planning. The geometrical reconstruction was performed using computed tomography scans and a total of 4680 shell elements were meshed on the median surface of the head skeleton with the particular characteristic of adapted mesh density and real element thickness. The assessment protocol of the finite element model was achieved using a quasi-static experimental compression test performed on the zygomatic bone area of a defleshed isolated head. Mechanical behavior of the finite element model was compared to the real one and the assessment approach was divided into two steps. First, the mechanical properties of the anatomical structure were identified using the simulation and then the simulated displacement field was compared to local displacement measurement performed during test using a digital correlation method. The assessment showed that the head skeleton model behaved qualitatively like the real structure. Quantitatively, the local relative error varied from 8% up to 70%.

The field performance of frontal air bags: a review of the literature

This article presents a broad review of the literature on frontal air bag field performance, starting with the initial government and industry projections of effectiveness and concluding with the most recent assessments of depowered systems. This review includes as many relevant metrics as practicable, interprets the findings, and provides references so the interested reader can further evaluate the limitations, confounders, and utility of each metric. The evaluations presented here range from the very specific (individual case studies) to the general (statistical analyses of large databases). The metrics used to evaluate air bag performance include fatality reduction or increase; serious, moderate, and minor injury reduction or increase; harm reduction or increase; and cost analyses, including insurance costs and the cost of life years saved for various air bag systems and design philosophies. The review begins with the benefits of air bags. Fatality and injury reductions attributable to the air bag are presented. Next, the negative consequences of air bag deployment are described. Injuries to adults and children and the current trends in air bag injury rates are discussed, as are the few documented instances of inadvertent deployments or non-deployment in severe crashes. In the third section, an attempt is made to quantify the influence of the many confounding factors that affect air bag performance. The negative and positive characteristics of air bags are then put into perspective within the context of societal costs and benefits. Finally, some special topics, including risk homeostasis and the performance of face bags, are discussed.

The Effects of Depowered Airbags on Skin Injuries in Frontal Automobile Crashes

The purpose of this study was to determine the effects of depowered frontal airbags on the incidence of skin injuries. The National Automotive Sampling System database files from 1993 to 2000 were examined in a study including 2,246,524 occupants exposed to airbag deployment in the United States. There was no significant difference between full-powered and depowered airbags, with 60.2 percent of those exposed to a full-powered deployment sustaining a skin injury versus 59.5 percent of occupants exposed to a depowered airbag (p = 0.19). Whether occupants were exposed to a full-powered airbag (1,936,485 occupants) or a depowered airbay (310,039 occupants), the majority of skin injuries were to the upper extremity and the face. Regardless of airbag power, the overwhelming majority of the skin injuries were minor (99.8 percent). There was not a significantly greater risk of injury from any source for occupants exposed to a depowered airbag or a full-powered airbag (p = 0.87). The data suggest that the implementation of depowered airbags did not affect the number, seriousness, location, or source of skin injuries.

Differences in the location and multiplicity of mandibular fractures in Kuwait, Canada and Finland during the 1990s

OBJECTIVE

To compare the location and multiplicity of mandibular fractures in Kuwait, Canada and Finland during the 1990s.

SUBJECTS AND METHODS

Data were collected from several hospitals in Kuwait (1991-2000), Toronto General Hospital in Canada (1995-2000) and Oulu University Hospital in Finland (1990-1999). The data were analyzed statistically using chi-square test, ANOVA, t test and logistic regression.

RESULTS

Condylar fractures were more common in Finnish patients (41%) than Canadian (35%) or Kuwaiti patients (21%). Condylar fractures caused by falls were about 3.4 times more common in Kuwait and Finland compared to Canada. In Finland the risk of road traffic accidents caused by condylar fracture was about 4 times higher than those caused by other etiologies. In Canada male gender was about 2 times higher for the condylar fracture than female gender. Female patients often had more multiple injuries than men in all three countries and multiple fractures were observed especially in traumas caused by falling.

CONCLUSION

Differences in location and multiplicity of mandibular fractures are due to differences in etiologies and demographic patterns.

Temporomandibular joint pain following airbag deployment on the face: a case report

Varieties of injuries have been reported as a result of the deployment of the airbag/s following road traffic accidents. The purpose of this case-report is to present a physiotherapist's perspective of a patient who was diagnosed as having temporomandibular pain and dysfunction following the deployment of the airbag on the face and its implications for the dental profession. The patient was assessed using a modified Maitland assessment procedure to establish the diagnosis and the treatment consisted of Maitland mobilisation techniques, pulsed short wave diathermy and ultrasound as and when indicated directed to the upper cervical spine. The outcome of this case-report suggests that the temporomandibular symptoms presented by this patient were of cervical origin. Therefore, it is suggested that the cervical spine should be routinely examined in patients presenting with temporomandibular pain and dysfunction following trauma and early referral to physiotherapy may facilitate early recovery.

Effect of restraint systems on maxillofacial injury in frontal motor vehicle collisions

PURPOSE

Motor vehicle collisions (MVCs) are the leading cause of maxillofacial fractures. Additionally, maxillofacial injuries are the most common injury related to air bag deployment. We sought to characterize the occupant restraint system (seat belt and air bag) and collision characteristics associated with MVC-related maxillofacial injuries.

MATERIALS AND METHODS

The 1991-2000 National (United States) Automotive Sampling System Crashworthiness Data System (CDS) data files were used. The CDS is a national probability sample of passenger vehicles involved in police-reported tow-away MVCs. Analysis was limited to front seat occupants involved in frontal collisions of delta-V (estimated change in velocity) of greater than 15 km/hr. The risk of facial injury was calculated according to occupants' restraint use (unrestrained, seat belt only, air bag only, and seat belt and air bag combined) and compared using risk ratios (RRs) and associated 95% confidence intervals (CIs).

RESULTS

Occupants restrained with a seat belt only (RR, 0.48; 95% CI, 0.40 to 0.57) or a seat belt and an air bag (RR, 0.83; 95% CI, 0.73 to 0.94) had a significantly reduced risk of any facial injury compared with completely unrestrained occupants. There was no association for those restrained with an air bag only (RR, 1.19; 95% CI, 0.82 to 1.73). A similar pattern of results was observed for moderate to severe facial injuries and for facial fractures.

CONCLUSION

Seat belt use significantly reduces the risk of facial injury in frontal MVCs. Air bag use was not associated with the risk of facial injury.

Burn injuries resulting from (accidental) airbag inflation

INTRODUCTION

Airbags are intended to minimize facial injuries, alone and when used in combination with seatbelts in high-velocity motor-vehicle accidents. They may occasionally perforate, resulting in the release of sodium azide or sodium hydroxide, which result in chemical burns when in contact with skin. The force of deployment may itself result in significant blunt trauma, and there is a temperature rise during the inflation causing thermal burns, possibly as a separate and unnecessary consequence of a relatively minor accident.

METHOD

A case report is presented. The literature on such injuries was reviewed and the mechanism of airbag deployment commented.

CONCLUSION

Alternative designs and mechanisms of linking the activation of the device to the velocity of travel or to add a switch which is activated when accessing a motorway are recommended.

Cranio-maxillofacial trauma: a 10 year review of 9,543 cases with 21,067 injuries

INTRODUCTION

Cranio-maxillofacial trauma management requires pertinent documentation. Using a large computerized database, injury surveillance and research data describe the whole spectrum of injuries. The goal of this study was to assess the effect of the five main causes of accidents resulting in facial injury on the severity of cranio-maxillofacial trauma.

PATIENTS AND METHODS

During a period of 10 years (1991-2000) 9,543 patients were admitted to the Department of Oral and Maxillofacial Surgery, University Hospital of Innsbruck with cranio-maxillofacial trauma. Data of patients were prospectively recorded including cause of injury, age and gender, type of injury, injury mechanisms, location and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures and concomitant injuries. Statistical analyses performed included descriptive analysis, chi square test, Fisher's exact test, and Mann-Whitney's U test. This was followed by logistic regression analyses for the three injury types to determine the impact of the five main causes on the type of injury at different ages in facial trauma patients.

RESULTS

Five major categories/mechanisms of injury existed: in 3,613 (38%) cases it was activity of daily life, in 2991 (31%) sports, 1170 (12%) violence, in 1,116 (12%) traffic accidents, in 504 (5%) work accidents and in 149 (2%) other causes. A total of 3,578 patients (37.5%) had 7,061 facial bone fractures, 4,763 patients (49.9%) suffered from 6,237 dentoalveolar, and 5,968 patients (62.5%) from 7,769 soft tissue injuries. Gender distribution showed an overall male-to-female ratio of 2.1 to 1 and the mean age was 25.8+/-19.9 years; but both varied greatly depending on the injury mechanism (facial bone fractures: 35.4+/-19.5 years, higher risk for males; soft tissue injuries: 28.7+/-20.5, no gender preference; dentoalveolar trauma: 18+/-15.6, elevated risk for females). For patients sustaining facial trauma, logistic regression analyses revealed increased risks for facial bone fractures (225%), soft tissue lesions (58%) in patients involved in traffic accidents, and dental trauma (49%) during activities of daily life and play accidents. When compared with other causes, the probability of suffering soft tissue injuries and dental trauma, but not facial bone fractures, is higher in sports-related accidents, 12 and 16%, respectively.

CONCLUSION

This study differentiated between injury mechanisms in cranio-maxillofacial trauma. The specially trained surgeons treating cranio-maxillofacial trauma are the primary source of information for the public and legislators on implementing preventive measures for high-risk activities. In facial trauma, older persons are prone to bone fractures (increase of 4.4%/year of age) and soft tissue injuries (increase of 2%/year of age) while younger persons are more susceptible to dentoalveolar trauma (decrease of 4.5%/year of age).