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Technical Paper

Trauma to Children in Forward-Facing Car Seats

One of the leading causes of death and disability among young children is motor vehicle accidents. Although current child restraint systems (car seats) have significantly reduced mortality and morbidity, deaths and injuries still occur. Since it is not possible to correlate human child injury potential with the biomechanical devices used for high level impact testing using experimental methods, the acquisition and analysis of specific child injury data identifiable with real world automobile crashes is critical for input to biomechanical research, anthropometric test device (ATD) development and safety standard revisions. The purpose of this study was to analyze vehicular-related trauma that had occurred to children in known crash environments based on accident configuration and car seat design.
Technical Paper

Accident Investigation and Impairment Study of Lower Extremity Injury

The automotive safety community has grown increasingly aware of the societal costs of injury impairment and disability resulting from automobile accidents. A significant portion of this impairment can be attributed to lower extremity trauma. An accident data study was conducted to determine lower extremity injury frequencies and mechanisms for restrained front-seat occupants in frontal collisions. A query of the 1988-1990 NASS (National Accident Sampling System) data provided information on pelvis, femur, knee, leg, and ankle and foot injuries. Age, gender, seating position, and delta-V were examined for their effect on the data. Lower extremity injury data were compared with injury data of similar severity (AIS ≥ 2) for the head, chest, thorax, and abdomen. The NASS data was supplemented with injury impairment information which, combined with anthropomorphic and biomechanical data, provides a prioritization scheme for the design of dummy lower extremities and instrumentation.
Technical Paper

Adult Occupant Injuries of the Lower Limb

Lower limb injuries among motor vehicle occupants are relatively common and are one of the principle causes of permanent disability. The author has reviewed the current literature and his own experience as an orthopaedic surgeon and research accident investigator concerning lower limb injuries among motor vehicle occupants. An unreported series of knee, thigh, hip, pelvis injuries with indepth accident investigation is reported. Incidence rates for specific injury diagnoses are not available. Gross tabulations reveal that lower limb injury is second only to head injury in frequency among injured motor vehicle occupants. Lower limb injuries are possibly the commonest cause of permanent disability and impairment resulting from motor vehicle accidents.
Technical Paper

Evaluating Safety Regulations, Then and Now

The FMVSS were established to provide the public with uniform safety equipment and design standards based on sound research. Ongoing evaluation is essential to maintain the effectiveness and safety of FMVSS and to ensure that current technology is incorporated in standards development. Serious injury (AIS 3 or greater) reporting by NASS should be upgraded to facilitate standards evaluation and development. Although cost effectiveness is a mandated criteria for standards evaluation, the protection of human life and limb must remain the principle criteria for measuring effectiveness. A citizen's advisory panel, similar to the NMVSAC should be established to assist NHTSA in establishing priorities for standards evaluation, development and promulgation.
Technical Paper

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.
Technical Paper

Biomechanical Analysis of Swimming Pool Neck Injuries

This paper presents an analysis of 67 neck injuries incurred in diving and sliding accidents in swimming pools. The accidents were investigated to establish the appropriate medical and mechanical factors involved. A mathematical model was developed to allow the prediction of the trajectory and velocity of the subjects prior to their injury. Nine of the accidents were selected for real life simulation. The simulation included the selection of test subjects of similar physical build to the accident victims who then performed the maneuvers leading to the injury, but in deeper water. High speed movies (200 frames per second) were taken, above and below the water, to measure the motion. A frame by frame analysis provided data to determine the trajectory and velocity profiles of the test subject. The maneuvers studied included diving from the pool edge, diving from various board types and sliding down various sliding board configurations.
Technical Paper

Soft Tissue Injuries of the Neck

Whiplash is a poorly defined term including ligamentous and muscle strains, hematomas, disc injuries, and less frequently, brain, eye and ear injuries. Diagnosis is difficult because clinical signs and Xrays, electromyography and electroencephalography findings are few. Protection and rest will cure most patients within a year but approximately 2/5th of patients have permanent symptoms and disability. Rear-end impact accidents cause the head and neck to hyperextend over the seat back. Whiplash occurs in 38% of exposed occupants. Head rests give protection but differential rebound may occur producing injurious hyperextension and whiplash. The larynx, trachea and esophagus, in front of the spine, are injured by impact against the dash or steering wheel. Airway obstruction may occur and cause death if not restored quickly. Permanent disability can occur because of scarring and partial airway or esophageal obstruction or vocal cord damage.
Technical Paper

A Critical Assessment of the Use of Non-Human Responding Surrogates for Safety System Evaluation

The basic physical mechanisms underlying recent experimentally observed anomalous behavior in the impact performance of safety helmets evaluated with soft (human-like) and hard (magnesium alloy) headform surrogates are qualitatively and quantitatively explained in this paper. The principal and physical mechanisms brought to light in the headform surrogate investigation are directly applicable to the utilization of other forms of surrogates (head -neck, thorax, whole body). In particular the results raise a serious question as to the validity of using non-human responding surrogates, with human generated injury tolerance data, for the purpose of assessing safety system performance. The implications of the results are that good crash-impact protective devices (helmets, restraints, etc.) could be penalized and, equally important, less safe crash-impact protective system designs could result from improper assessment of safety system performance.
Technical Paper

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 tabulation 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 injury 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.
Technical Paper

Field Application and Research Development of the Abbreviated Injury Scale

The Abbreviated Injury Scale (AIS) introduced in January 1968 has been widely used by the Medical Engineering Accident Investigation Teams of the NHTSA, by the General Motors ADAP, by the NATO Country Teams in Europe, and by the AMA Physician-Police Teams. The experience and problems involved in use of the AIS are reviewed. An extended and revised AIS has been developed. Validation studies revealed better than 80% accuracy by multiple users. The Comprehensive Research Injury Scale (CRIS) has been completed for all major medical specialties. The CRIS separates the various criteria (energy dissipation-ED, threat to life-TL, permanent impairment-PI, treatment period-TP, incidence-IN) used with variable quantities and frequencies in the AIS. The CRIS identifies and quantitates each scaling criteria permitting more meaningful and detailed application of the AIS.
Technical Paper

The Medical Aspects of Driver Protection Systems and Devices Developed Through Automobile Racing

This three-part paper deals with the medical aspects of driver protection in automobile racing. Part one presents the history of car safety equipment beginning with the development of helmets, belts, roll bars, and other devices to protect competition drivers. This paper describes the evolution from purely optional to mandatory equipment and how their design and accident records have contributed to increased safety in passenger cars. The investigation of injuries sustained in crash, fire, and loss of control caused by road hazards have contributed to the many improvements discussed here, almost all of which are readily adaptable to passenger car models. The second part presents a summary of the influence of racing on the design, testing and performance standards for protective headgear. The significance is indicated of applying basic principles of mechanics and dynamic systems testing to all fields in which head impact is a potential hazard.
Technical Paper

Restraint Systems in Racing Accidents

Some 634 accidents occuring in races sanctioned by the Sports Car Club of America (SCCA) are reviewed. Shoulder harnesses were used in 275 of the accidents. Inverted “Y” or double, separately anchored, shoulder harnesses were used almost exclusively. A significant decrease in the frequency and severity of injuries occurred after harnesses were introduced. Injury from the restraint system was very infrequent; submarining occurred only once. Deep bucket seats, providing lateral support for the chest and forward support for the buttocks, appear to potentiate the effectiveness of restraint systems. The “Y” harness functions well in production seats without lateral support because lateral displacement of the shoulders and upper torso can occur without risk of neck injury.
Technical Paper

The Abbreviated and the Comprehensive Research Injury Scales

A widely accepted injury scale is urgently needed by medical engineering automotive accident investigation teams. An informal committee of physicians, engineers and other researchers has developed two scales. The Abbreviated Injury Scale (AIS) combines and details several existing scales including the DeHaven-Cornell scale, the commonly used police scale, and others. Injuries which are usually not fatal are rated with a 1 to 5 scale. Several scaling criteria were combined but with varying weights to establish the AIS rankings. The Comprehensive Research Injury Scale (CRIS) was developed to separate the criteria used in injury scaling. Five separate criteria are used: Energy Dissipation (ED), Threat-To-Life (TL), Permanent Impairment (PI), Treatment Period (TP), and Incidence (IN). The ED scale ranks energy dissipation in injury production, and will be of major value to vehicle designers concerned with human tolerance for injury.
Technical Paper

The Pathology and Pathogenesis of Injuries Caused by Lateral Impact Accidents

Forty-eight lateral impact accidents were studied correlating vehicle damage and occupant injury. Side-swipe accidents produced serious injury only when the occupant's elbow was protruding through a window or when the occupant space of the vehicle was seriously compromised. Intersection impacts and drifting impacts, particularly when the impact was caused by a vehicle approaching from the opposite direction, caused the most serious injuries. Fractures of the acetabulum with intrapelvic protrusion of the hip and fractures of the pubic rami are characteristic of lateral impact accidents. The door was the most common injury-producing structure of the vehicle. Deep wrap-around seat designs and stronger doors, door frames, and chassis structures are necessary to reduce occupant space penetration and to absorb impact energy in lateral impact accidents.
Technical Paper

Case Studies of Racing Accidents

A statistical study of sports car racing sanctioned by the Sports Car Club of America demonstrates the frequency of roll-over accidents and the infrequency of serious injury from such accidents. Detailed case studies from Watkins Glen Grand Prix Course are presented. Three similar rollover accidents taken from the author’s medical practice are presented for comparison. The use of roll bars for open cars is advocated.