Is Acceleration a Valid Proxy for Injury Risk in Minimal Damage Traffic Crashes? A Comparative Review of Volunteer, ADL and Real-World Studies

Injury claims associated with minimal damage rear impact traffic crashes are often defended using a “biomechanical approach,” in which the occupant forces of the crash are compared to the forces of activities of daily living (ADLs), resulting in the conclusion that the risk of injury from the crash is the same as for ADLs. The purpose of the present investigation is to evaluate the scientific validity of the central operating premise of the biomechanical approach to injury causation; that occupant acceleration is a scientifically valid proxy for injury risk. Data were abstracted, pooled, and compared from three categories of published literature: (1) volunteer rear impact crash testing studies, (2) ADL studies, and (3) observational studies of real-world rear impacts. We compared the occupant accelerations of minimal or no damage (i.e., 3 to 11 kph speed change or “delta V”) rear impact crash tests to the accelerations described in 6 of the most commonly reported ADLs in the reviewed studies. As a final step, the injury risk observed in real world crashes was compared to the results of the pooled crash test and ADL analyses, controlling for delta V. The results of the analyses indicated that average peak linear and angular acceleration forces observed at the head during rear impact crash tests were typically at least several times greater than average forces observed during ADLs. In contrast, the injury risk of real-world minimal damage rear impact crashes was estimated to be at least 2000 times greater than for any ADL. The results of our analysis indicate that the principle underlying the biomechanical injury causation approach, that occupant acceleration is a proxy for injury risk, is scientifically invalid. The biomechanical approach to injury causation in minimal damage crashes invariably results in the vast underestimation of the actual risk of such crashes, and should be discontinued as it is a scientifically invalid practice.

Musculoskeletal injury in military Special Operations Forces: a systematic review

IntroductionSpecial Operations Forces conduct military activities using specialised and unconventional techniques that offer a unique and complementary capability to conventional forces. These activities expose Special Operations Forces personnel to different injury risks in comparison with personnel in the conventional forces. Consequently, different injury patterns are expected in this population. The purpose of this research is to establish high-level evidence informing what is known about musculoskeletal injury epidemiology in Special Operations Forces.MethodsA systematic review was conducted using three online databases to identify original studies reporting musculoskeletal injury data in Special Operations Forces. A critical appraisal tool was applied to all included studies. Descriptive data were extracted for demographics, study design details and injuries (eg, injury frequency, injury type, body part injured, activity, mechanism, severity). Results were narratively synthesised.ResultsTwenty-one studies were included. Trainees conducting qualification training had the highest injury frequency, up to 68% injured in a training period. The ankle, knee and lumbar spine were the most common body parts affected. Parachuting caused the most severe injuries. Physical training was the most common activity causing injury, accounting for up to 80% of injuries. Running and lifting were common injury mechanisms. Injury causation information was frequently not reported. Partially validated surveillance methods limited many studies.ConclusionsInjuries are prevalent in Special Operation Forces. Future research should prioritise identifying injury causation information that supports prevention. Focus on improving surveillance methods to enhance the accuracy and comparison of results across cohorts is also recommended.

Applying a systems thinking lens to injury causation in the outdoors: Evidence collected during 3 years of the Understanding and Preventing Led Outdoor Accidents Data System

IntroductionThis article presents a detailed systems analysis of injury incidents from 35 Australian led outdoor activity organisations between 2014 to 2017.MethodInjury incident reports were collected using a specific led outdoor activity incident reporting system known as UPLOADS (Understanding and Preventing Led Outdoor Accidents Data System).ResultsIn total, 1367 people sustained injuries from across 20 different activities, with an injury rate of 1.9 injured people per 1000 participants over the three-year period. A total of 2234 contributory factors from multiple levels of the led outdoor activity system were identified from the incident reports, and 361 relationships were identified between contributory factors.DiscussionThis systems analysis of injury incidents demonstrates that it is not only factors within the immediate context of the incident (Participants, Environment, Equipment) but factors from across multiple systemic levels that contributes to injury incidents (Schools, Parents, Activity centre management). Prevention efforts should focus on addressing the whole network of contributing factors and not only the prominent factors at the lower system levels within the immediate context of the injury incident occurrences.

Effects of Aging on Impairment Ratings: Part 4: Musculoskeletal Issues

This article is the fourth of five in a series on the effects of age-related changes in impairment evaluations as defined by the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth and Sixth Editions. The present article addresses the musculoskeletal system and differs from the first three articles, which focused on apportionment of an impairment rating between aging and other causes. The medical literature supports the notion that age-related osteoarthritis (OA) changes in the hand and digits frequently are associated with injury and/or repetitive motion. Thus, apportionment is indicated, but deciding which came first, the imaging abnormality or the injury, requires consummate skill on behalf of the rating physician. OA also occurs in the knees and hips of older individuals. Diffuse idiopathic skeletal hyperostosis (DISH) is a noninflammatory disorder characterized by calcification and ossification of spinal ligaments and entheses and is unique, in the authors’ opinion, because of a positive correlation between aging and back pain caused by this condition. The article also addresses the association—or the lack thereof—between pathology and aging, as well as degenerative changes and symptoms, to facilitate causation analysis. For a fuller discussion of causation analysis for the spine, readers can consult the AMA Guides to the Evaluation of Disease and Injury Causation, Second Edition.

Coupling Simulation of an Impact-Induced Rollover Accident and Evaluation of Curtain Airbag Effectiveness

The causes of fatal and serious injuries in rollover accidents have yet to be fully identified. This study aimed to reconstruct a complex accident, based on both video analysis and vehicle coupling simulation. Besides, the major fatal injury causation and curtain airbag’s effectiveness were analyzed. The coupling model, including finite element tire and multi-body vehicle body, was developed to estimate the vehicle trajectory. A validated curtain airbag (CAB) module, was introduced for occupant protection effectiveness evaluation. The vehicle trajectory from the simulation correlated well with that from video recordings and simulation result indicated that passenger’s head contact with road (maximum contact force 9834.9[Formula: see text]N) was assumed to be the main reason of the victim death. After introducing the CAB, the maximum head acceleration was reduced from 129.1[Formula: see text]g to 24.9[Formula: see text]g, and the neck Fz was reduced by 80.0% as well. The coupling simulation method turned out to be efficient to reconstruct certain complex accident case. Such study is beneficial for further similar accident reconstruction and restraint system evaluation.

Risk Factors for Lateral Ankle Sprains and Chronic Ankle Instability

Lateral ankle sprains (LASs) are a common injury sustained by individuals who participate in recreational physical activities and sports. After an LAS, a large proportion of individuals develop long-term symptoms, which contribute to the development of chronic ankle instability (CAI). Due to the prevalence of LASs and the propensity to develop CAI, collective efforts toward reducing the risk of sustaining these injuries should be a priority of the sports medicine and sports physiotherapy communities. The comprehensive injury-causation model was developed to illustrate the interaction of internal and external risk factors in the occurrence of the inciting injury. The ability to mitigate injury risk is contingent on a comprehensive understanding of risk factors for injury. The objective of this current concepts review is to use the comprehensive injury-causation model as a framework to illustrate the risk factors for LAS and CAI based on the literature.

Shoulder Pain at Work: Causation Analysis

In most cases of shoulder injury at work, causation analysis is not clear-cut and requires detailed, thoughtful, and time-consuming causation analysis; traditionally, physicians have approached this in a cursory manner, often presenting their findings as an opinion. An established method of causation analysis using six steps is outlined in the American College of Occupational and Environmental Medicine Guidelines and in the AMA Guides to the Evaluation of Disease and Injury Causation, Second Edition, as follows: 1) collect evidence of disease; 2) collect epidemiological data; 3) collect evidence of exposure; 4) collect other relevant factors; 5) evaluate the validity of the evidence; and 6) write a report with evaluation and conclusions. Evaluators also should recognize that thresholds for causation vary by state and are based on specific statutes or case law. Three cases illustrate evidence-based causation analysis using the six steps and illustrate how examiners can form well-founded opinions about whether a given condition is work related, nonoccupational, or some combination of these. An evaluator's causal conclusions should be rational, should be consistent with the facts of the individual case and medical literature, and should cite pertinent references. The opinion should be stated “to a reasonable degree of medical probability,” on a “more-probable-than-not” basis, or using a suitable phrase that meets the legal threshold in the applicable jurisdiction.

Compensability of Common Upper Extremity Conditions When Work Activities Are Repetitive

Repetitive illness sometimes is wrongly called repetitive injury or cumulative trauma, but the latter are misnomers because the employee cannot identify a specific injury as a cause of the symptoms. In workers’ compensation, such gradual illness claims may be compensable if the condition arises during the course of employment, which requires that it be caused by occupational duties, exposures, or equipment used on the employer's premises. Expert impairment evaluators face three requirements: they must know the best scientific evidence currently available regarding causation of the condition(s) in question, ie, generic causation; the facts of the individual case, ie, specific causation; and the legal threshold in the applicable jurisdiction for acceptance of a condition as work related. The AMA Guides to the Evaluation of Disease and Injury Causation, Second Edition, is an excellent resource and provides the physician a blueprint for the assessment of causation in occupational injury and illness claims. The book adopts the methodology developed by the National Institute for Occupational Safety and Health and the American College of Occupational and Environmental Medicine. When asked to render opinions regarding causation, a physician is wise to consider this methodology in determining the work relatedness of the condition. Medical opinions based on an accepted methodology and the best scientific evidence will result in better patient outcomes.