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From the crash investigation files at the University of Michigan Transportation Research Institute (UMTRI), the crashes involving deployed airbags were reviewed. The total number of deployments is 898 of which 764 are frontal crashes with the principal direction of force (PDF) at 11-1 o’clock. Of the drivers in these frontal crashes 83% were using the belt restraint. Overall, seven of ten drivers have an AIS-0 or 1 level injury as the maximum or highest injury severity level (MAIS). Of the survivors, one in six had a moderate level injury (AIS-2) as their most significant injury and one in nine had an MAIS 3 or greater injury. Fatalities are rare. There is a difference between injury severity frequencies of belted vs. non-belted drivers. Three-quarters of the belted drivers had minor injuries compared to only half of those not belted. A difference was also noted at the AIS-2 level—belted vs. unbelted 14% vs. 23%.

This is an overview of air bag injuries, a review of the literature and descriptions of air bag related injuries to the various body areas. Some unusual injuries are also included. The cases presented are from the author's files and one from the Special Studies Division of NHTSA.

Using the CDC (SAE J224), a comparison of the NASS data and the UMTRI field accident files (UM series) indicates a similar distribution of offset frontal crashes. Offset frontal damage occurs in 56-61% of crashes, often involving more than one third of the front of the car. Lap-shoulder belted drivers sustain more AIS 2 or greater injuries when there is interior intrusion and occur more often when the offset damage is in front of the driver. However, this may well be due to the severity of the crash. European studies have no uniformity as to offset frontal collision descriptors are difficult to interpret, or to compare one to another.

From our crash investigations of air bag equipped passenger cars, a subset of upper extremity injuries are presented that are related to air bag deployments. Minor hand, wrist or forearm injuries-contusions, abrasions, and sprains are not uncommonly reported. Infrequently, hand fractures have been sustained and, in isolated cases, fractures of the forearm bones or of the thumb and/or adjacent hand. The close proximity of the forearm or hand to the air bag module door is related to most of the fractures identified. Steering wheel air bag deployments can fling the hand-forearm into the instrument panel, rearview mirror or windshield as indicated by contact scuffs or tissue debris or the star burst (spider web) pattern of windshield breakage in front of the steering wheel.

From the authors' files, case examples of thoracolumbar injuries sustained by lap-shoulder belted front seat occupants, in frontal crashes, are presented. Additional cases were found in a review of the clinical literature. The biomechanical literature was reviewed, identifying laboratory studies on thoracolumbar spinal injuries. Suggested mechanisms in the production of these injuries in frontal type car crashes are postulated.

The “seat belt syndrome”, first described in 1961, identified abdominal organ injuries related to the use of the lap belt. Many articles have further documented detailed descriptions of intraabdominal lap belt related trauma. Lumbar spine distractions were later added to this injury list. Lap belt injury literature not infrequently hypothecates that some, if not all, of these seat belt syndrome injuries would be prevented, eliminated, or at least significantly reduced in frequency by the use of lap-shoulder belts. This report, based on data from crash investigations, documents lap-shoulder belt intraabdominal injuries occurring by belt loading alone, without significant intrusion and without significant dynamic flexing of the torso of the restrained front seat occupant.

The effects of child safety seats have been well documented in the medical literature. Scattered throughout the medical literature are individual case reports of cervical injury to children restrained in child restraint systems. A review of the literature is provided identifying previous documented cases. The authors also provide new case details of children with cervical spine injury without head contact. An overview of the growth of the infant and specific details in the cervical spine that may contribute to significant cervical injury without head impact is presented.

Crash injury reduction via lap-shoulder belt use has been well documented. As any interior car component, lap-shoulder belts may be related to injury in certain crashes. Relatively unknown is the fact that cervical fractures or fracture-dislocations to restrained front seat occupants where, in the crash, no head contact was evidenced by both medical records and car inspection. An extensive review of the available world's literature on car crash injuries revealed more than 100 such cases. A review of the NASS 80-88 was also conducted, revealing more examples. Cases from the author's own files are also detailed.

NASS 80-88 passenger side impacts data were analyzed. Location of primary car damage using the CDC classification, the AIS for injury severity studies, and the interior contacts of the various body areas. Drivers alone, or with passengers were studied separately in both left and right side crashes. Direct impacts to the passenger compartment only are less frequent than to other CDC side zones. Driver interior contacts vary by body region but also by side impacted in the crash. The presence of an unrestrained front passenger appears to enhance driver injury level in left side crashes but the presence of a passenger, in right side crashes appears to moderate driver injury severity.

Frontal crashes (11-1 o'clock) were reviewed from the National Accident Severity Study file (NASS) for years 1980-87. Adult drivers and front right passengers, with lower extremity injuries of the pelvis, thigh, knee, leg or ankle/foot were reviewed. Analysis of age differences, injury contacts, and effectiveness of the 3-point restraint system were studied. Unrestrained drivers have a higher frequency of knee injuries than passengers, fewer leg injuries than passengers and both have the same frequency of ankle/foot injuries. Older unbelted drivers have more injuries to the pelvis, leg, and ankle/foot region than do young drivers. Passengers have more leg injuries. The instrument panel is the major contact for most of the lower extremity injuries. Lap/shoulder belts significantly reduce lower extremity injury frequency.

This paper presents an analysis of the NASS file (1980 - 1986). Cases were selected for near side impacts for drivers, i.e. left side of car, involving unrestrained adult drivers who were alone in the car, and who were not involved in any other collisions following the primary left side impact. Data analysis indicates that 11 % of the near side drivers had crush damage to only the passenger compartment, the ‘P’ zone, that the head, chest and abdomen predominate as the body areas of concern (AIS 3+ injuries), but that these injuries are sustained more often on structures other than the side interior.

Basilar skull fractures have previously been described as the result of cranial vault impacts. Such fractures resulting from impacts to the chin, face and/or orbital areas (non-cranial vault areas) have not been adequately documented. These types of fractures and the motor vehicle incidents in which the injuries were sustained will be described according to the type of crash and vehicles involved. Data on the tolerance levels of the basilar region of the skull are sparce at best. Case histories of non-cranial vault impacts, presented in a variety of crash types, document that facial impacts can be the sole cause of basilar skull fractures. A historical review of the basilar skull fracture literature is presented.

A review of the UM series and of NCSS, NASS, CPIR and FARS Files, as well as Michigan accident data files was undertaken, as well as a review of the NTSB “Rear Seat Study”. From these files rear seat occupany is approximately 10%, with children 6 years of age or less being 1/5th of these. About 50-60% of those in the sear seat are adults. Most of the injuries are at the lower AIS levels, with adults being more seriously injured. Of the more serious or fatal injuries, the head and face predominate by far, in all types of crashes involving unrestrainded rear seat occupants. When belts are worn there are few seriously or fatally injured rear occupants and of these, the abdominal area predominates. From available data, rear lap-belted passengers have the same MAIS level (or less) when compared to their front seat lap-shoulder belted counterparts.

An analysis of 211 automobiles having the ball-type E.A. device (GM cars - 1972–1980), involved in frontal crashes was made to determine the relationship between driver injury and the steering assembly. The majority of the drivers had MAIS of 0 or 1 (66%). The head was the most frequently injured body region with the lower extremities next in frequency. Of the unrestrained drivers studied, 43% had a thoracic injury, the majority of which were minor. There is no correlation between injury severity and steering rim or spoke deformation, or the amount of E.A. column compression. Specific terminology for certain aspects of the E.A. performance are suggested.

The purpose of this literature review was to determine areas of automotive injury information that may add to knowledge of injury type, frequency, severity, and cause. This paper is a review of the literature concentrating on the period between 1965 and present. Literature on car, van, or 1ight truck occupants has been reviewed for injury frequencies, types, and locations. Current experimental biomechanical articles are also included. A search was made for descriptions of injury frequency, restraint effectiveness, and the causes of specific injuries. Medical and engineering journals, texts, and books were reviewed. For convenience, this report is divided into sections by body region with an overview introduction on the anatomy of the specific region.

This paper presents an analysis of front seat outboard occupants in frontal and rollover crashes. These occupants were lap belted, lap-shoulder belted or were unrestrained. In the frontal crash the lap-shoulder belt reduces the occurrence of the severe, serious, critical-to-life injuries, and fatalities in all regions of the body (head, neck, thorax, lower torso and extremities). In addition, there is a strong association between belt usage and the occupant escaping from the crash with no injury. In rollover crashes, belts reduce the frequency of the more severe injuries by preventing the occupant from being ejected. For those occupants not ejected from the car, belts effectively reduce fatalities and the more serious injuries.

From field crash investigations conducted by the authors, a series of well documented crashes will be presented. In each, at least one occupant was wearing a lap-shoulder belt. Detailed injury reports will be presented along with photographs of car damage, occupant contact areas, and where possible, the estimated impact speeds.

Modulation of the occupant's movement within the vehicle by the seat belt reduces the potential for striking certain structures and decreases severity of the injuries. The seat belt also functions to direct the upper torso, especially the head, to specific interior surfaces. Design modifications of these areas are needed to prevent serious facial fractures that have been seen. Lap belted drivers contact the steering wheel rim or instrument panel in front of the wheel in head-on crashes; the front passenger strikes the upper instrument panel. Improper positioning of the lap seat belts produces serious intraabdominal injury, especially in the case of the rear passengers. Seat belt fatality cases were, in general, due to collapse and compromise of the occupant space as typified by the broadside intersection collision.