John D. States

INJURY FREQUENCY AND HEAD RESTRAINT EFFECTIVENESS IN REAR-END IMPACT ACCIDENTS

All of the rear-end impact accidents occurring in the City of Rochester, New York, in a three-month period were surveyed by tabliation of the police accident reports. Special police information forms, telephone interviews, and mail questionnaires were used for further data acquisition. Vehicle photographs and medical examinations were conducted for approximately every 20th vehicle. During the data collection period, 691 rear-end impacts occurred. Although a computer program revealed 1371 accidents, defects in the program accounted for the large difference. Whiplash injury frequency based on telephone interview and mail questionnaire data obtained one to seven days after the accident revealed a whiplash frequency of 38%, which was approximately twice that determined by on-scene police investigators. Head restraints reduced whiplash frequency by 14% and fixed head restraints appeared to be more effective. Seventy percent of adjustable head restraints were in the downmost position. Women sustained whiplash injury more frequently (51%) but benefited from head restraints more (whiplash injury frequency 38%). An extensive review of the literature related to whiplash injury and head restraint design and effectiveness is presented. /Author/

FATAL INJURIES CAUSED BY UNDERARM USE OF SHOULDER BELTS

Safety belt use has dramatically increased in the past decade in North America because of safety belt use laws. Underarm use of shoulder belts is a means of relieving neck irritation and other complaints from shoulder belts but may result in serious or fatal injuries. Loads far in excess of the injury tolerance of the lower chest and upper abdomen are imposed by the shoulder belt in the underarm position. Six recent cases are presented in which fatal injury was caused by underarm use of shoulder belts. Lacerations of the liver, spleen, intestines, mesentery, diaphragm, and aorta, and spine injury have occurred in accidents, most of which should have been survivable. The motoring public must be warned that underarm use of shoulder belts is hazardous and may cause fatal injuries in otherwise survivable accidents.

Cervical fractures and fracture-dislocations sustained without head impact

Because of its flexibility and structure, the cervical spine is disposed to various mechanisms of injury: although not so common as injuries caused by head impacts, cervical fractures and/or fracture-dislocations have been reported without direct impact to the head. Some cervical injuries reported have been sustained by wearers of lap and shoulder belts in auto accidents; however, we do not consider belt use a potential hazard because ample evidence has accrued in the medical and engineering literature to document general injury and fatality reduction by use of seatbelts. We believe that in many instances occupants would be more seriously injured or killed were belts not worn. The present paper reviews reports of cervical injuries without head impact found in the literature and case histories of such injuries from the Highway Safety Research Institute of The University of Michigan, as well as experimental studies in animals, cadavers, and volunteer subjects.

Lower extremity injuries in automobile crashes

The new United States National Crash Severity Study (NCSS) data on tow-away automobile crashes was reviewed to determine the details of the more severe injuries of the lower extremity. This review includes the frequency of injury by limb segments (pelvis, thigh, knee, leg and ankle/foot), the vehicle structure contacted to produce these injuries, and the injuries/contact differences among car occupants. Some of the finds are: of the various body regions having the more severe injuries, the lower extremity ranks second only to the thorax; lap-shoulder belted occupants hardly ever sustain the more severe lower extremity injuries; and severe lower extremity injuries occur primarily in frontal crashes. Extrapolation of the NCSS data for national estimates indicates that the more serious lower extremity injuries in car crash survivors approximately equals the total number of passenger car occupants who are killed annually (27,000).

A time comparison study of the New York State Safety Belt Use Law utilizing hospital admission and police accident report information

New York state enacted the first safety belt use law in the United States in 1984. We evaluated the effects of the law by reviewing all hospital admissions from motor vehicle crashes in Monroe County, New York. We compared admissions for the 18 months prior to the effective date of the law with those for the 18 months after the law became effective. Police accident reports and hospital records were coupled and intensively reviewed. Motorcyclists, pedestrians, and bicyclists (bicycle collisions with motor vehicles) became controls for the study. Seat belt usage was determined from police and hospital record information. Analysis of the data revealed that safety belt use among patients hospitalized because of motor vehicle accidents increased from 11.2% before the law became effective to 53% after the law became effective. Hospital admissions decreased 11.9% among motor vehicle occupants and increased 2.6% among controls. The ISS decreased from 16.01 to 14.55 for motor vehicle occupants and increased from 14.77 to 15.11 among controls. Among subjects all injuries decreased except injuries of the spine and abdomen, which increased in the postlaw period.

DEATHS FROM MOTOR VEHICLE CRASHES: PATTERNS OF INJURY IN RESTRAINED AND UNRESTRAINED VICTIMS

A time comparison study of motor vehicle crashes in Monroe County, New York, from 1983 to 1986 was completed. Using a database of police accident reports, hospital logs, and autopsy reports from the county coroner, the hospital and autopsy reports of 91 unrestrained and 27 restrained fatally injured victims were reviewed. The hypothesis was that safety belts do not change patterns of injury in fatally injured victims. Patient data, seating position, and direction of impact were the same for both groups, while ejections occurred only in the unrestrained group (19.8%). Injury Severity Score (ISS), major injuries in AIS-85 categories for the Head, Thorax, Abdomen, and in AIS-85 Code 5 or 6 categories for the Head, Thorax, Abdomen were the same in unrestrained and restrained victims, except for the greater incidence of cerebral contusions in the unrestrained group (71% vs. 37%, p = 0.002). Cranial injuries were the most likely cause of death in nearly two thirds of the victims in both groups. The incidence of major head (other than cerebral contusion), thoracic, and abdominal injuries in unrestrained and restrained fatally injured victims was the same. This suggests that severe collisions with crushing, intrusion, or significant deceleration exceed the ability of restraints to prevent many fatal injuries.

Psychiatric Disorders and Motor Vehicle Accidents

The literature has often suggested a relationship between psychiatric illness and increased risk for motor vehicle accidents but few data exist, particularly those from prospective or case-controlled studies. The present study examined detailed accident and injury data from a large series (N = 1778) of motor vehicle crashes that included persons with diagnoses of psychiatric illnesses (n = 17); matched controls were also studied. As expected, drivers with psychiatric diagnoses used psychotropic medications more frequently than did controls. Drivers with psychiatric diagnoses did not have more frequent single-car crashes, unsafe speed or failure to yield violations, or less restraint use than did controls. Such drivers did less often drive motorcycles and tended to be less often cited for alcohol use. Implications of these results for efforts toward prevention and for further study are discussed.

CHARACTERISTICS OF MOTOR VEHICLE ACCIDENTS RESULTING IN SPINAL CORD INJURY

The majority of cases of spinal cord injury (SCI) occur during car crashes. Yet, relatively little is known about the precise accident factors involved. The present study investigated 30 cases of SCI in automobile drivers that occurred in a series of 91 spinal cord injuries. A matched control group was also studied. SCI drivers were not different from controls in terms of mortality, number of rollover crashes, alcohol use, citations for contributing human factors, nighttime accidents, or unfavorable weather and road conditions. However, SCI drivers less frequently used restraints. Results are discussed in terms of preventive measures, specifically, those concerning restraint use, alcohol use, and driving behavior.