Air Bag-Induced Orbital Blow-Out Fractures

Factors influencing the incidence of maxillofacial fractures

PURPOSE

Maxillofacial injuries occur in a significant proportion of trauma patients. Trauma causes considerable economic expense due to procedural costs, the time a patient is off work, and the associated loss of income. For these reasons, it is an important health and economic issue. The aim of this study is to discuss the factors that may influence the incidence of maxillofacial fractures. As it is necessary to determine trends to help guide the development of new methods of injury prevention, preventative measures are also discussed.

METHODS

An electronic search was undertaken in March 2011, including articles published between 1980 and 2011 with the terms "facial fractures" and "maxillofacial fractures" in the title. The texts of epidemiological studies were reviewed in order to identify factors that may influence the incidence of maxillofacial fractures.

RESULTS

From the selected articles, ten factors were identified: age, gender, geographic region and cultural aspects, socioeconomic status, temporal and climatic influence, use of alcohol and drugs, compliance with road traffic legislation, domestic violence, osteoporosis, and etiology of the maxillofacial trauma.

CONCLUSIONS

Care of injured patients should include not only management of the acute phase, but also combine preventive programs and interventional programs aimed at reducing the incidence of maxillofacial fractures. Therefore, there is a need to ensure strict compliance of traffic rules and regulations, implement improvement in automotive safety devices, organize prevention programs to minimize assaults, implement school education in alcohol abuse and handling potentially hostile situations (especially for men), improve protection during sporting activities, and legislate wearing of protective headgear in workers. Preventive strategies remain the cheapest way to reduce direct and indirect costs of the sequelae of trauma. Societal attitudes and behaviors must be modified before a significant reduction in the incidence of maxillofacial fractures will be seen.

Interaction of hydraulic and buckling mechanisms in blowout fractures

The etiology of blowout fractures is generally attributed to 2 mechanisms--increase in the pressure of the orbital contents (the hydraulic mechanism) and direct transmission of impacts on the orbital walls (the buckling mechanism). The present study aims to elucidate whether or not an interaction exists between these 2 mechanisms. We performed a simulation experiment using 10 Computer-Aided-Design skull models. We applied destructive energy to the orbits of the 10 models in 3 different ways. First, to simulate pure hydraulic mechanism, energy was applied solely on the internal walls of the orbit. Second, to simulate pure buckling mechanism, energy was applied solely on the inferior rim of the orbit. Third, to simulate the combined effect of the hydraulic and buckling mechanisms, energy was applied both on the internal wall of the orbit and inferior rim of the orbit. After applying the energy, we calculated the areas of the regions where fracture occurred in the models. Thereafter, we compared the areas among the 3 energy application patterns. When the hydraulic and buckling mechanisms work simultaneously, fracture occurs on wider areas of the orbital walls than when each of these mechanisms works separately. The hydraulic and buckling mechanisms interact, enhancing each other's effect. This information should be taken into consideration when we examine patients in whom blowout fracture is suspected.

The effect of reclined seats on mortality in motor vehicle collisions

BACKGROUND

Motor vehicle collisions are the leading cause of trauma-related death in the United States. Reclined seatbacks may alter crash kinetics and affect occupant outcome. We examined the effect of reclined seatbacks on occupant mortality.

METHODS

Our study population consisted of United States traffic crashes from 1995 to 2005, using data from the Crash Injury Research and Engineering Network and the National Automotive Sampling System Crashworthiness Data System. Phase 1, we performed a detailed review of crash kinetics and biomechanical factors resulting in injury patterns in fully reclined occupants. Phase 2, we performed a population-based retrospective cohort study comparing outcome in upright, partial, and full recline positions. Primary outcome measure was 30-day mortality.

RESULTS

Phase 1, flexion and compression injuries over pretensioned lap and shoulder belts resulted in severe thoracoabdominal and spine injuries in restrained occupants, with a high associated mortality. Increased lower extremity injuries from additional force loads into bolsters and panels were also noted. Phase 2, the majority (>50%) of front-seat occupants was partially reclined. Fully reclined occupants were younger (30 vs. 39 years, p < 0.0001), more likely to be male (70% vs. 49%, p < 0.0001) and less likely to wear a seat belt (58% vs. 78%, p < 0.0001) than upright or partially reclined occupants. Mortality was increased in both partially (adjusted odds ratio 1.15, 95% confidence interval 1.05-1.26) and fully reclined occupants (adjusted odds ratio 1.77, 95% confidence interval 1.09-2.88).

CONCLUSION

The reclined position is associated with increased occupant mortality in motor vehicle collisions.