Jamie L. Moore

Upper extremity injuries related to airbag deployments

OBJECTIVE Details on airbag injuries to the upper extremity are relatively unknown to clinicians. The injuries presented here should provide a clear understanding of the mechanisms of forearm, hand, and wrist injuries that may be seen by emergency room physicians. MATERIALS AND METHODS From our crash investigations of 325 airbag-equipped passenger cars, a subset of upper extremity injuries are presented that are related to airbag deployments. MAIN RESULTS 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, wrist, and fingers. The close proximity of the forearm to the airbag module door is related to most of the fractures identified. Steering wheel airbag deployments can fling the hand-forearm into the instrument panel, rearview mirror, or windshield, as indicated by contact scuffs, tissue debris, or the star burst (spider web) pattern of windshield breakage in fron of the steering wheel. CONCLUSION Minor injuries of the upper extremity can occur when contacted by the deploying airbag either directly or by flinging the hand-forearm into interior car structures. Fractures of the forearm are rare and usually are due to direct impact by the forceful opening of the airbag module door.

Air bag injuries and occupant protection.

Analysis of the investigations of crashes involving automobiles equipped with air bags verifies the estimations of the lifesaving and injury reduction benefits of this supplemental restraint system. Cases of air bag-associated injuries, primarily erythema, abrasions, and contusions of the lower face and anterior throat-upper chest, are identified as those most often observed. Corneal-scleral injuries were infrequently noted but are rarely found in crashes involving air bag deployments.

UPPER EXTREMITY INJURIES RELATED TO AIR BAG DEPLOYMENTS

Case studies of upper extremity injuries related to air bag deployments are presented. Such injuries range from forearm and hand erythema, contusions, lacerations, or thermal burns, to fractures or dislocations of the thumb, wrist, and forearm. The close proximity of the forearm or hand to the air bag module door is related to most of the fractures identified. Air bag deployments from the steering wheel can fling the hand-forearm into the instrument panel, rearview mirror or windshield.

Vehicle LATCH system features associated with correct child restraint installations

Objective: Lower anchors and tethers for children (LATCH) was intended to standardize the attachment between child restraints and vehicle seats. However, LATCH implementations vary, resulting in differences in ease of attachment of child restraint connectors. Identifying vehicle characteristics associated with correct child restraint installations can provide guidance for designing vehicle LATCH systems that increase correct child restraint installations. Methods: The LATCH system and other relevant vehicle characteristics were documented in 98 top-selling 2010–2011 vehicles. These features, together with proposed LATCH usability recommendations from the International Organization for Standardization and Society of Automotive Engineers, were used to select 12 vehicles for volunteer testing with a range of LATCH system characteristics. Thirty-six volunteers were assigned to 4 groups; each group tested 3 vehicles, 4 child restraints (infant, rear-facing convertible, forward-facing convertible, and combination seat), and 2 installation methods (lower anchors and seat belt) in a split-plot experimental design. Mixed-effects logistic regression models were used to identify predictors of tight installation and correct lower anchor use. Results: Vehicle survey results indicated that most vehicle manufacturers provide the minimum number of LATCH hardware locations required by regulation. Among 21 vehicles with a third row, 4 had no tether anchors and 11 had no lower anchors in the third row. Study volunteers correctly used the lower anchors in 60 percent of LATCH installations and used the top tether in 48 percent of forward-facing installations. When the tether was used, use was correct in 46 percent of trials (22% of all forward-facing installations). Only 13 percent of all trials had completely correct child restraint installation (correct use of lower anchors or seat belt, correct tether anchor use, tight seat installation, and correct installation angle). Tight installation was 3.3 times as likely with correct lower anchor use compared to trials with incorrect use. Three lower anchor characteristics were associated with rates of correct lower anchor use above 50 percent: clearance angle around the lower anchors greater than 54°, attachment forces less than 178 N, and anchor depth within the seat bight of less than 2 cm. Vehicles meeting all 3 criteria were 19 times as likely to have lower anchors used correctly compared to vehicles meeting none of the criteria. No vehicle features predicted either use of tethers or correct use of tethers. Conclusions: Vehicle LATCH systems that improve lower anchor accessibility could increase the rate of correct lower anchor use, but more research is needed to understand factors associated with tether use and correct use.

Using in-depth investigations to identify transportation safety issues for wheelchair-seated occupants of motor vehicles

In-depth investigations of motor-vehicle crashes involve detailed inspection, measurement, and photodocumentation of vehicle exterior and interior damage, evidence of belt-restraint use, and evidence of occupant contacts with the vehicle interior. Results of in-depth investigations thereby provide the most objective way to identify current and emerging injury problems and issues in occupant safety and crash protection, and provide important feedback on the real-world performance of the latest restraint-system and vehicle crashworthiness technologies. To provide an objective understanding of real-world transportation safety issues for wheelchair-seated travelers, the University of Michigan Transportation Research Institute (UMTRI) has been conducting and assembling data from in-depth investigations of motor-vehicle crashes and non-crash adverse moving-vehicle incidents, such as emergency vehicle braking, turning, and swerving, in which there was at least one vehicle occupant sitting in a wheelchair. The results of 39 investigations involving 42 wheelchair-seated occupants have been assembled and entered into a wheelchair-occupant crash/injury database. In addition, a biomechanical analysis of each case has been performed to identify key safety issues for wheelchair-seated travelers. The wheelchairs of 34 of the 42 occupants who were seated in wheelchairs while traveling in motor vehicles were effectively secured by either a four-point, strap-type tiedown system or a docking securement device, and all but one of these properly secured wheelchairs remained in place during the crash or non-collision event. However, 30 of the 42 occupants were improperly restrained, either because of non-use or incomplete use of available belt restraints, or because the belt restraints were improperly positioned on the occupants body. Twenty-six of the 42 occupants sustained significant injuries and 10 of these occupants died as a direct result of injuries sustained, or from complications resulting from those injuries. These findings, when combined with the analyses of the individual cases, point to a need for better driver and caregiver education and training on how to properly secure wheelchairs and position belt restraints on wheelchair-seated passengers. They also point to a need for improved restraint systems used by wheelchair-seated drivers, and a need for wheelchair designs that facilitate the proper use and positioning of vehicle-anchored belt restraints.

Survey of LATCH vehicle hardware

Ninety-eight 2010–2011 model year vehicles were surveyed to evaluate the usability of hardware known as Lower Anchors and Tethers for Children, or LATCH, required by US FMVSS 225. Most vehicles do not provide LATCH hardware beyond the minimum number of required seating positions. Only seven vehicles had three sets of LATCH hardware in the second row. In 21 vehicles with third rows, four had no tether anchors and 11 had no lower anchors in the third row. Relative to proposed the Society of Automotive Engineers (SAE) recommendations, 59 vehicles met the recommended lower attachment force of 75 N or less but only 2 vehicles met the recommended clearance angle of at least 75º. The depth of lower anchors relative to the bight was less than 2 cm in 28 vehicles, 2–4 cm in 34 vehicles and greater than 4 cm in 36 vehicles. Most tether anchors were on the seat back (42) or rear filler panel (35).