Kathryn L. Loftis

CT Based Three-Dimensional Measurement of Orbit and Eye Anthropometry

PURPOSE To measure eye and orbit anthropometric variation within the normal population by using CT images and to determine the effects of age and sex on eye and orbit anthropometry. Quantification of eye and orbit anthropometric variation within the normal population and between persons of different age and sex is important in the prediction and prevention of eye injury. METHODS A systematic method was developed to align head CT images three dimensionally and to measure ocular and orbital parameters in 39 subjects. Twenty-four measurements were collected along the orbital rim, to quantify the orbital aperture. Protrusions of the brow and the eye were measured, along with relative distances, to describe location of the eye within the orbit. RESULTS The orbit widened with age, and significant relations were identified between orbital aperture and eye location measurements, both of which varied significantly between the sexes. CONCLUSIONS The comprehensive set of measurements collected in this study provides three-dimensional information on orbit geometry, as well as placement of the eye within the orbit. These measurements and the methodology used will contribute to the development of finite element models of the orbit and eye for computational modeling purposes and may be useful in the design of eye protection equipment.

Biomechanical modeling of eye trauma for different orbit anthropometries

In military, automotive, and sporting safety, there is concern over eye protection and the effects of facial anthropometry differences on risk of eye injury. The objective of this study is to investigate differences in orbital geometry and analyze their effect on eye impact injury. Clinical measurements of the orbital aperture, brow protrusion angle, eye protrusion, and the eye location within the orbit were used to develop a matrix of simulations. A finite element (FE) model of the orbit was developed from a computed tomography (CT) scan of an average male and transformed to model 27 different anthropometries. Impacts were modeled using an eye model incorporating lagrangian-eulerian fluid flow for the eye, representing a full eye for evaluation of omnidirectional impact and interaction with the orbit. Computational simulations of a Little League (CD25) baseball impact at 30.1m/s were conducted to assess the effect of orbit anthropometry on eye injury metrics. Parameters measured include stress and strain in the corneoscleral shell, internal dynamic eye pressure, and contact forces between the orbit, eye, and baseball. The location of peak stresses and strains was also assessed. Main effects and interaction effects identified in the statistical analysis illustrate the complex relationship between the anthropometric variation and eye response. The results of the study showed that the eye is more protected from impact with smaller orbital apertures, more brow protrusion, and less eye protrusion, provided that the orbital aperture is large enough to deter contact of the eye with the orbit.

Development of a robust mapping between AIS 2+ and ICD-9 injury codes

Motor vehicle crashes result in millions of injuries and thousands of deaths each year in the United States. While most crash research datasets use Abbreviated Injury Scale (AIS) codes to identify injuries, most hospital datasets use the International Classification of Diseases, version 9 (ICD-9) codes. The objective of this research was to establish a one-to-one mapping between AIS and ICD-9 codes for use with motor vehicle crash injury research. This paper presents results from investigating different mapping approaches using the most common AIS 2+ injuries from the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS). The mapping approaches were generated from the National Trauma Data Bank (NTDB) (428,637 code pairs), ICDMAP (2500 code pairs), and the Crash Injury Research and Engineering Network (CIREN) (4125 code pairs). Each approach may pair given AIS code with more than one ICD-9 code (mean number of pairs per AIS code: NTDB=211, ICDMAP=7, CIREN=5), and some of the potential pairs are unrelated. The mappings were evaluated using two comparative metrics coupled with qualitative inspection by an expert physician. Based on the number of false mappings and correct pairs, the best mapping was derived from CIREN. AIS and ICD-9 codes in CIREN are both manually coded, leading to more proper mappings between the two. Using the mapping presented herein, data from crash and hospital datasets can be used together to better understand and prevent motor vehicle crash injuries in the future.

Investigation of the Safety Effects of Knee Bolster Air Bag Deployment in Similar Real-World Crash Comparisons

Objective: The lower extremity is the most frequently injured body region and knee–thigh–hip (KTH) injuries account for half of these injuries. Knee bolster air bags (KBABs) have been incorporated in some vehicles to serve as an additional restraint for the occupants knees and reduce KTH injuries. To investigate the safety benefits of KBABs, similar frontal crashes with opposing KBAB deployment were selected from the Crash Injury Research and Engineering Network (CIREN) database. Methods: An 8-point similarity scoring algorithm was used to quantify crash and occupant similarity and select case comparisons. A total of 183 cases without a KBAB were scored for similarity to 9 KBAB cases. These similarity scores were used to select 31 final case comparisons. The effect of KBAB deployment on occupant injury patterns was investigated with a particular focus on KTH injuries. Results: Over half of the occupants exposed to a KBAB sustained no KTH injuries and a reduction in femur fractures was observed in KBAB occupants (P = .036). However, increases in proximal tibia/fibula and foot/ankle fractures were observed in KBAB occupants (P = .022 and .002, respectively). Mildly significant decreases in pelvic fractures and Abbreviated Injury Scale (AIS) 2+ head injuries were observed in the KBAB occupants, supporting the notion that KBABs reduce forward occupant excursion (P = .094 and .055, respectively). Investigation of each case comparison yielded further insight into the reasons for injury pattern differences between cases with opposing KBAB deployment. In addition to KBAB deployment status, differences in occupant factors (age, height, and weight) and crash factors (delta V and belt use) between the cases for a particular comparison could explain variation in injury patterns. Conclusions: The current study presents a preliminary in-depth qualitative and quantitative assessment of KBAB safety benefits. However, further investigation is recommended to provide conclusive evidence of KBAB effectiveness.

Development of an expert based ICD-9-CM and ICD-10-CM map to AIS 2005 update 2008

ABSTRACT Objective: This article describes how maps were developed from the clinical modifications of the 9th and 10th revisions of the International Classification of Diseases (ICD) to the Abbreviated Injury Scale 2005 Update 2008 (AIS08). The development of the mapping methodology is described, with discussion of the major assumptions used in the process to map ICD codes to AIS severities. There were many intricacies to developing the maps, because the 2 coding systems, ICD and AIS, were developed for different purposes and contain unique classification structures to meet these purposes. Methods: Experts in ICD and AIS analyzed the rules and coding guidelines of both injury coding schemes to develop rules for mapping ICD injury codes to the AIS08. This involved subject-matter expertise, detailed knowledge of anatomy, and an in-depth understanding of injury terms and definitions as applied in both taxonomies. The official ICD-9-CM and ICD-10-CM versions (injury sections) were mapped to the AIS08 codes and severities, following the rules outlined in each coding manual. The panel of experts was composed of coders certified in ICD and/or AIS from around the world. In the process of developing the map from ICD to AIS, the experts created rules to address issues with the differences in coding guidelines between the 2 schemas and assure a consistent approach to all codes. Results: Over 19,000 ICD codes were analyzed and maps were generated for each code to AIS08 chapters, AIS08 severities, and Injury Severity Score (ISS) body regions. After completion of the maps, 14,101 (74%) of the eligible 19,012 injury-related ICD-9-CM and ICD-10-CM codes were assigned valid AIS08 severity scores between 1 and 6. The remaining 4,911 codes were assigned an AIS08 of 9 (unknown) or were determined to be nonmappable because the ICD description lacked sufficient qualifying information for determining severity according to AIS rules. There were also 15,214 (80%) ICD codes mapped to AIS08 chapter and ISS body region, which allow for ISS calculations for patient data sets. Conclusion: This mapping between ICD and AIS provides a comprehensive, expert-designed solution for analysts to bridge the data gap between the injury descriptions provided in hospital codes (ICD-9-CM, ICD-10-CM) and injury severity codes (AIS08). By applying consistent rules from both the ICD and AIS taxonomies, the expert panel created these definitive maps, which are the only ones endorsed by the Association for the Advancement of Automotive Medicine (AAAM). Initial validation upheld the quality of these maps for the estimation of AIS severity, but future work should include verification of these maps for MAIS and ISS estimations with large data sets. These ICD-AIS maps will support data analysis from databases with injury information classified in these 2 different systems and open new doors for the investigation of injury from traumatic events using large injury data sets.

A similarity scoring technique to analyse comparisons of real-world crashes to crash tests: initial results from a 12-point system

The most similar crash test was identified for each of 100 Crash Injury Research and Engineering Network (CIREN) cases. To quantify the best comparison pairs, a Similarity Scoring Methodology (SSM) with 12 parameters was developed. The results showed 18 comparisons with ‘low’ (0–6 points), 72 with ‘medium’ (7–9 points) and 10 with ‘high’ (10–12 points) similarity scores. Thirty-nine CIREN cases received a similarity point for deltaV (within range: ±16.1 kph [10 mph]). Thirty-seven CIREN cases had a lower deltaV than the crash test. For occupant parameters, seating position and airbag deployment received similarity points most frequently (86% each). Occupant height and weight received points least frequently (41% and 20%, respectively), typically because CIREN occupants were shorter and heavier compared with Anthropometric Test Device (ATD) sizes. This work establishes a standard SSM to be used with future studies and provides information about key differences between crash tests and real-world crashes.

187 Expert-developed ICD-AIS map for measuring serious road traffic injuries

Background The problem of serious road injury has not decreased in comparison to the drop in fatal road injuries. Unlike the standard definition adopted for fatal road injuries, serious injury has not been as well defined in Europe. However in 2012 the High Level Group on road safety agreed to the defining of serious injury in EU countries as Maximum Abbreviated Injury Scale 3+ (MAIS3+). The AAAM was commissioned by the Transport and Mobility, Road Safety Unit of the European Commission to develop a MAIS3+ serious injury map from the International Classification of Diseases (ICD-9 and ICD-10) to the Abbreviated Injury Scale (AIS 2005 Update 2008). Methods The study involved an expert panel comprising ICD coding experts and certified AIS specialists to map ICD-9-CM and ICD-10-CM codes to the AIS 2005 Update 2008 identifying the following levels of severity: MAIS3+ injury, MAIS 1 and 2 and ‘no map’ cases. Rules were invoked based on the AIS principles of coding practice to ensure the MAIS descriptors were a true reflection of how an injury descriptor in ICD would be coded manually to the AIS by a certified AIS specialist. Results Overall for the injury-based codes of ICD-9-CM, 781 codes (31%) were mapped to a MAIS severity at the level of MAIS3+, 1297 codes (52%) were mapped at the level of MAIS1 or 2 and 426 codes (17%) could not be mapped. For the much larger set of injury-based codes of ICD-10-CM, 2323 codes (14%) were mapped to a MAIS severity at the level of MAIS3+, 9700 codes (59%) at the level of MAIS1 or 2, and 4485 (27%) could not be mapped. Conclusions The application of the AAAM’s expert derived AIS-ICD map is a solid foundation for identifying serious injury at MAIS3+ for road traffic injuries. This AIS-ICD map offers a comprehensive approach to serious road injury definition for the EU and will enable countries to set measureable road safety targets for the reduction of serious road traffic injury using a comparable definition.

Similarity scoring methodology for comparing real-world cases to crash test standards

A National Automotive Sampling System–Crashworthiness Data System (NASS–CDS) based Similarity Scoring Methodology (SSM) is presented for the quantitative comparison of real-world crashes to crash tests. Using NASS–CDS 2000–2008, five categorical and five continuous crash, vehicle and occupant parameters were utilised for frontal and side impacts. Mahalanobis metric results revealed that 1% of frontal and 23% of side NASS–CDS cases scored received similarity scores of <0.14 demonstrating greater similarity to standard crash tests. These included 20,334 frontal and 442,511 side impact case occupants (weighted). On average, the best scores occurred for NASS–CDS cases compared to FMVSS 214 side crash tests. The majority of real-world crashes had lower delta-Vs and maximum crush than associated crash tests. The results will aid in the study of occupant safety and vehicle crashworthiness by helping researchers identify population groups to study real-world injuries versus the injury risk predicted by anthropomorphic test devices.