Documentation:FIB book/Sex-Specific Differences in Injury Biomechanics of a Car Crash
Introduction
Anthropometric test devices (ATDs), commonly known as crash test dummies, have been used since the mid-1900s when Sierra Sam was developed in 1949 by Sierra Engineering.[1] This dummy and its successors were a reasonable initial approach to replacing cadaveric testing with a durable and reusable model. However, concerns persisted regarding the biofidelity of ATDs. To address the existing gaps, General Motors (GM) introduced the Hybrid II Family of ATDS in 1972. This new product could replicate the size, shape, mass, and arm and leg motion of the 50th percentile adult male. In an effort to represent a wider range of the population, GM developed the scaled-down version of the Hybrid II (50th percentile male) to represent the 5th percentile female population.[1] In 1986, the Hybrid III, an improved version of the Hybrid II, and its “female” version were authorized by the National Highway Traffic Safety Administration (NHTSA). The Hybrid III remains the most commonly used ATD to date.[2] However, the Hybrid III is no longer an accurate representation of the current North American population as it has shifted in size since the 1980s. Specifically, between the late 1980s to the early 2010s, the average American became 15 pounds heavier due to the rising prevalence of obesity without a significant change in height.[3][4]
During the late 1990s, NHTSA began the development of an advanced mid-size adult male ATD for frontal impacts named the Test Device for Human Occupant Restraint (THOR). Despite GM, NHTSA, and other companies recognizing the importance of creating a more biofidelic ATD, developers still did not place substantial emphasis on the lack of biofidelic female representation. Most female ATDs are simply scaled-down versions of the mid-sized adult male ATD.[5] They do not consider the anatomic and physiological differences between the sexes, leading to an oversight in addressing these distinctions. This oversight is evident in the failure to account for anatomical differences in bone and cartilage, impacting the determination of injury risks. For example, females are particularly susceptible to whiplash in rear impacts and show a higher incidence of lower extremity fractures in frontal impacts. The odds of Abbreviated Injury Scale (AIS) 2+ and 3+ injuries are 2.4 and 1.7 times higher for females than males, respectively. Additionally, females have 3.8 times higher odds of sustaining an ankle injury due to a car collision.[6] These statistics reinforce the need for a more comprehensive and inclusive approach to ATD design and development that considers the unique injury patterns and vulnerabilities experienced by females in automobile collisions.
The gold standard for safety testing of vehicles involves utilizing ATDs to assess how humans are affected in collision scenarios. The lack of a biofidelic female ATD highlights a significant controversy in vehicle safety development that has yet to be addressed completely, despite research elucidating anatomical and bone resistance differences between the sexes. It is crucial to note that there exists an imbalance between car safety testing and real-world statistics. In car safety testing, many evaluations position the “female” ATDs in the passenger seat rather than the driver's seat. This systemic discrepancy in safety testing for females extends beyond the laboratory and into the real world, where automobile designs are generally designed and tested for the 50th percentile of the male population. This leaves the female population at a huge safety risk in vehicle collisions.[7]
Due to the underrepresentation of females in research and safety testing, coupled with the increasing number of female drivers, females face a 45% higher risk of neck injuries, 22% higher risk of head injuries, and 80% higher risk of leg injuries.[8] The difference in injury risk based on sex for lower limb injuries is of particular importance due to the statistical significance of reported differences and the absence of safety equipment specifically designed for lower leg injuries. Existing safety equipment in cars is not well-suited for females either; belt-restrained female drivers are 47% more likely to sustain a severe injury than their male counterparts.[8][9] The primary controversy in this section revolves around the inadequacy of current female ATDs and car safety testing setups to accurately represent the female population. This deficiency contributes to reported variations in injury risks to the lower limbs. Although "female" ATDs are utilized, design modifications for safety equipment and the performance testing of such safety equipment predominantly rely on the mid-sized adult male dummy.[8]
The purpose of this section is to emphasize the biomechanics of different lower limb injuries, the anatomical differences in lower limbs between sexes, and how these differences may influence injury risk. It explores the consequences of neglecting these distinctions and inadequately representing females in safety testing, resulting in variations in injury risk between males and females in vehicle collisions. Lastly, the section highlights the limitations in existing models and research, proposing potential areas for future work to address these limitations and enhance safety, benefiting not only female drivers but all drivers.
Vehicle Collision Lower Limb Injury Biomechanics
Upper Leg Vehicle Collision Injuries
The most common femur fracture resulting from car collisions is a femoral shaft fracture.[10] Several cadaver tests have been conducted to determine the injury risk of femur fractures due to knees contacting the dashboard. Setups include deceleration sleds into a barrier, and pendulum or pneumatic frontal impacts to the knee in flexion.[11] In frontal vehicle collisions, the knees contact the dashboard, causing the loading at the knee to transfer to the femoral condyle. This creates axial compression of the femur, generating a posterior-to-anterior bending moment.[10] The bending moment results from the angle of the femoral neck which then renders the knee impact load eccentric to the femoral head.[11] Tensile stress created by the bending is the mechanism causing injury in long bones, as bones are the weakest under tension.[11] The femoral shaft is the most vulnerable portion of the femur to fracture due to the weakening effect of the curvature of the femur as the cross-section decreases towards the shaft.[10] Several articles propose that muscle activation caused by the anticipatory clenching before impact preloads the femur, increasing the bending moment and making the femur more susceptible to fracture.[12]
In an automotive crash, various knee injuries can occur, including a rupture of the posterior cruciate ligament (PCL). This occurs when the tibial tuberosity collides with the front of the dashboard, pushing the tibia rearwards towards the trunk of the person. A large tensile strain forms on the PCL, leading to a rupture.[11] Modern vehicle dashboards are designed with a slope away from the knee to help prevent this injury. When the patella impacts a surface obliquely, it undergoes a sliding motion that loads the patellar ligament under tension, possibly causing a patellar ligament avulsion.[13] If the knee collides with the dashboard in a way that only the patella is impacted, a stellate (a star-shaped fracture of the patella caused by a direct blow)[14] fracture may occur. As the force of impact would not be borne by the condyles of the femur when the knee collides with a stiff surface, the rearward motion of the patella could also fracture the condyle notch.[11][10] It is hypothesized that if a deformable material is used for the dashboard, the impact load could be distributed to the femur condyles, preventing a knee fracture, as shown in the figure illustrating the impact of a dashboard stiffness on knee injuries, and as validated through cadaveric testing.[11] Excessive padding on the dashboard, however, can lead to the knee becoming pocketed in the dashboard, creating shear forces in the plane of the dash. This creates bending moments on two axes, possibly causing a fracture of the femoral shaft. It is important to note that the FMVSS 208 only has injury criteria for femur load and not for the knee joint; however, joint injuries are generally more debilitating.[11]
Lower Leg Vehicle Collision Injuries
There are several common injuries that can occur in the lower leg due to frontal car collisions. A pilon fracture, a fracture of the distal tibia, is prevalent in instances of footwell intrusion. Footwell intrusion occurs when any vehicle component penetrates into the space designated for the feet in the front seats. The combination of long bone compression and additional external force from muscle activation during car braking leads to this type of fracture. This was verified using a cadaveric below-the-knee model, where muscle activation was stimulated using a tendon catcher, and the foot was impacted with a pneumatic ram at the bottom of the foot in line with the tibia.[11] Encapsulation of the knee or foot can also cause fractures of the tibia and fibula due to torsional forces, in addition to the medial perpendicular forces from the forward motion of the occupant and footwell intrusion in the opposite direction.[15]
Ankle injuries can result from automotive crashes due to the dorsiflexion of the ankle associated with heavy braking coupled with footwell intrusion, as the ankle has a tolerance in dorsiflexion of 45 degrees.[11] The forward motion of the occupant, combined with the intrusion of the pedal into the foot, can exceed this tolerance, leading to injury. A common site for fractures and ligament tears in the ankle due to these biomechanics is the medial malleolus and calcaneofibular ligament respectively.[10][15]
A common mode of foot injury is inversion or eversion of the foot, which can be caused by footwell or brake intrusion. Inversion leads to injuries in the lateral aspect of the foot, while eversion results in injury to the medial aspect.[11] When foot eversion or inversion is combined with axial load, it can lead to medial and lateral ligament tears, malleolar fractures, and tibial osteochondral fractures.[10] In fact, panic braking itself can also result in injuries to the foot; when the force on the Achilles tendon becomes too large, it can cause fracture of the calcaneus.[11] Shorter drivers may experience fractures and dislocations of the metatarsal bones, as they tend to lift their foot during braking, causing plantar flexion and flexing of the toes, creating a large compressive load at the tarsometatarsal joints.[11]
Sex-Specific Anatomical Differences in the Lower Limb
It is known that many anatomical differences exist between females and males that are not accounted for in the ATDs that represent different sexes. The failure to consider these differences, particularly how females differ from males, puts females at a higher risk of injury. The following paragraphs highlight the anatomical lower limb differences between the sexes and infer how these differences may contribute to variations in the risk of the numerous injuries described in the previous section.
Sex-Specific Anatomical Differences in the Upper Leg
Despite the implication of the female ATD design as a scaled-down version of the male ATD, females are not “little males”. Physicians have reported anatomic variations in the thigh and knee joint between the sexes, extending beyond size differences.[16] These variations may contribute to differences in injury risks during car collisions. Specifically, the female pelvis features a deeper acetabular cup, oriented less horizontally and laterally compared to males. This results in a larger reactive surface for the femur to act on the acetabulum. Females also have smaller femoral heads. Collectively, these factors enhance hip stability, thereby potentially reducing the risk of hip injuries while increasing the risk of thigh and knee injuries.[15]
Studies have demonstrated that, irrespective of height, there is a difference in the medial-lateral dimensions between females and males in the proximal aspect of the tibia and the distal end of the femur. Females also have a less pronounced anterior condyle height, and their knees have a more trapezoidal shape, which may alter the risk of fractures in the condyle notch. Furthermore, there is a difference in quadriceps angle, defined as the angle between the vector of the combined pull of the quadriceps femoris muscle proximally and the patellar tendon distally.[16] This angle is generally larger for females due to the average wider width of the hips, causing the patella to track at a wider angle over the femoral condyle. [16]
Sex-Specific Anatomical Differences in the Lower Leg
The ankle joint, a complex interweaving of muscle, cartilage, and ligamentous tissue connecting to the 26 bones and 33 individual joints in the foot and ankle, given the high complexity of the ankle and foot area, anatomical differences could potentially be more pronounced in this region, exhibiting high variability in morphology between males and females. For example, males tend to have larger tibia and wider calcaneus bone, whereas females tend to have a longer calcaneus, elucidating anatomical differences in ankle bone composition between sexes.[17] These distinctions extend to ligaments and muscles of the ankle, impacting range of motion (ROM) differences. Females exhibit a larger ROM in plantar flexion, correlated with stronger plantar flexion strength, yet isometric strength tests reveal lower strength in both plantar flexion and dorsiflexion in females compared to males.[18]
There are also differences observed in ankle ligament laxity between the sexes. The laxity, or looseness, of a ligament can be influenced by hormonal fluctuations during the menstrual cycle, as estrogen and progesterone trigger the release of relaxin, a hormone that impacts ligament laxity.[19] A study conducted by Wilkerson & Mason in 2000[20] found that females generally have a higher ankle ligament laxity than males. Although sex differences in laxity are most notably observed in the knee due to the prevalence of anterior cruciate ligament (better known as ACL) injuries, they are also notable in the ankle joint. When considering the bone strength and size of the lower leg, specifically the tibia, males exhibit larger morphometrics.[21]
Given these observed sex differences in various components of the ankle, it is reasonable to assume that females experience car crashes differently from an anatomical perspective. This assumption is supported up by research done in frontal car crashes. An investigative study by Bangert et al. in 2023 [22] examining the CISS database found an increased injury risk in females for distal tibia fractures in crashes involving the toe panel or foot controls of the occupant’s leg. This trend is also evident when searching the NHTSA database for injury vulnerability: females have an 80% higher risk of injuring their leg than males in a car crash.[23] While minimal research is specifically done on the biomechanics of ankle and foot injuries observed during car crashes, according to NHTSA database, females had a higher risk of injury for lower extremities, especially for the foot and ankle, in frontal crashes reaching an AIS of 2 or higher.[24] The biomechanical, anatomical, and muscular differences observed between sexes likely have an impact on most injury risks during car crashes.
Sex-Specific Injury Risk
Differences in Injury Prevalence and Severity
The analysis of sex-specific injury risk within the context of car collisions reveals significant sex disparities in both injury prevalence and severity. To understand the overarching trends in lower limb injury risk between the sexes, multiple epidemiological studies were reviewed. However, these studies were unable to definitively determine the exact reasons for the observed results. Anatomical differences between females and males are hypothesized to alter injury biomechanics, leading to distinct injury risks, as discussed in preceding paragraphs.
Lower leg injuries, constituting a substantial portion of AIS 2+ injuries in motor vehicle crashes, have raised concerns about the increased vulnerability of females in car crashes. Despite the relatively lower fatality risk associated with lower limb injuries, such injuries can result in poor clinical outcomes and persistent disabilities long after the collision.[22] Pilon fractures, as discussed earlier, result in high rates of healing complications and bone infections, and even potential amputation in some cases.[22]
While historically the total number of car collision cases involving male occupants has been higher than those involving females, this sex gap is narrowing in recent years as driving exposure becomes more equitable between males and females.[6] A study by Bose et al. in 2011 [8] found data indicating that the rate of injurious crashes is higher for female drivers than male drivers, with female drivers experiencing 1.52 injurious crashes per million vehicle miles traveled compared to 1.26 such crashes per million miles. This study used multivariate regression strategies, allowing them to control for other effects and factors while specifically investigating sex as a predictor for injury. While traffic data suggests that female drivers may be equally likely to be involved in a crash, the underrepresentation of females in car collision injury research has led to understudied or inconclusive results. This emphasizes the necessity for a more reliable representation of the female population in biomechanical analyses and sex-specific injury prevention measures.[8]
Factors Influencing Injury Risk
Biomechanical factors contributing to differences in injury tolerance between sexes encompass bone mineral density, local bone and ligament geometry, and material properties, as highlighted in the previous section.[6] In 2015, Foreman et al.[6] used data from the NASS-CDS from 1998 to 2015 and found that the most significant sex-related impact on the risk of injury was observed in the lower extremities, even after adjusting for variables such as age, height, BMI, and delta-V (where delta-V represents the severity of a collision by measuring the change in the vehicle velocity before and after the collision). This study suggests that sex plays a role in determining injury tolerance due to the differences in body measurements or exposure to collisions. Notably, the study adopted a random sampling approach when selecting papers in this field to mitigate potential biases in their results[6], thereby strengthening the quality of their data.
The prevalence of lower extremity injuries in female occupants compared to their male counterparts is attributable to various factors. One noteworthy trend is that females tend to sit closer to the steering wheel, heightening the likelihood of collision with the vehicle interior.[22] Although some studies suggest that male occupants may have a reduced risk of specific lower leg injuries, such as distal tibia injuries, these results do not consistently achieve statistical significance. To address the relationship between sex and distal tibia fractures, analyses were conducted while accounting for similarly sized occupants, acknowledging the interdependence of sex and height, with height being known to correlate with the risk of lower leg injuries.[8][22]
The sex disparities in injury risk extend beyond lower leg injuries, encompassing a broad spectrum of lower limb and whole-body injuries. In a study conducted by NHTSA, a substantial sample size of 37,731,601 females and 41,477,848 males were analyzed. Females displayed significantly higher injury odds ratios (OR > 1.0; p-value < 0.05) for whole body/occupant maximum AIS (MAIS) 2+ and MAIS 3+ injuries.[25] Specifically, the study reported that females exhibit increased odds of sustaining AIS 2+ injuries, particularly in the foot and ankle during frontal crashes and when limited to the role of drivers. Female drivers had a much higher estimated risk of leg injuries relative to males: 98.5 ± 30.8 percent.[25] Furthermore, female drivers are more vulnerable to leg fractures resulting from toe-pan intrusion.[25]
Safety Measures
In 2015, a study by Ye et al. [26] examined the effects of age, BMI, and sex on severe injuries in motor vehicle crashes, highlighting the distinct risks that males and females face in such situations. It was found that in crashes of equal severity, females tend to be more susceptible to injury or fatality.[26] However, males have exhibited a higher likelihood of being unbelted in the driver position during accidents, with a higher prevalence of driving pickup trucks or utility vehicles.[26] Females often drive smaller and lighter vehicles than males, a difference that may place them at a disadvantage in the event of a collision leading to more severe outcomes.[27] Some experts argue that females' short stature and their tendency to sit closer to the wheel reduce the protection provided by standard safety devices, potentially leading to an increased risk of lower extremity injuries in frontal crashes.[22] The complex interplay between sex, vehicle size, and injury patterns underscores the need for further investigation to understand these sex-related variations and the existing safety device discrepancies. However, it is clear that females are at larger risk for lower limb injuries in vehicle collisions, and current ATD and test setups are inadequate in developing safety measurements and equipment.
Research on sex-specific injury risk in lower limb biomechanics analysis for car collisions has illuminated various disparities between males and females. While the focus has traditionally been on male-specific safety measures, it is important to recognize the distinct injury risks faced by females and to develop safety strategies that provide equitable protection for all occupants. Further studies are needed to delve deeper into the biomechanical factors underlying these differences and to close the existing gap in injury prevention.
Limitations and Future Work
Several epidemiology studies presented throughout this section had limitations to their work that may have affected the outcome of the results. Some studies reported differences in lower leg injury risks between females and males, suggesting that females are at higher risk of lower leg injuries, but these differences were found to be statistically insignificant.[22] This could be attributed to the sampling scheme used, resulting in small sample sizes. In 2011, another study by Bose et al. [8] was unable to determine the confounding effects of seating position in relation to sex and how that may affect injury risk. Lastly, the study done by Ye et al. in 2015[26] included vehicles dating back to 1998, and it was hypothesized that restricting the vehicle models to the last ten years prior to the study would have led to an overall reduction in injury risk due to advancements in safety equipment.
As described earlier, many of the injuries sustained in the lower limbs during frontal collisions are associated with height differences between males and females. However, even though these differences are not directly linked to sex and are more correlated with height, females are more likely to experience serious injuries in the lower limb.[8] Despite these distinct injury patterns between males and females, many vehicle tests using ATDs only evaluate the “female” ATD in the passenger seat. These disparities suggest that more testing should be conducted at the extremes of height differences in the driver's seat with ATDs to address a larger breadth of the population and mitigate inherent sex disparities in injury type and severity.
Importantly, the size of the vehicle fleet in North America has shifted significantly over the last 25 years towards an increased market share of large vehicles. According to CBC News, in 2020, about 80% of vehicle sales in Canada consisted of SUVs, pickups, and vans; this is compared to just less than 50% of vehicle sales in 1995. Further, even with this change in the vehicle fleet, females are still more likely to drive passenger vehicles as opposed to larger vehicles.[28][29]
According to a 2018 literature review by Ammori [15] examining the risk of fractures in females compared to males in frontal collisions in relation to car fleet size, the most recent research conducted addressing this issue was conducted by Thomas and Frampton in 1999.[30] When investigating the difference in injury outcomes in frontal collisions related to the car size and sex, they found that “those in smaller cars sustain more severe injuries and have a higher fatality rate”.[30] This finding, coupled with the fact that the majority of female drivers use smaller vehicles, could be what leads to the larger quantity and severity of lower limb injuries seen in females, as described earlier. This highlights the need for future research dedicated to enhancing the safety of female drivers. This involves developing models that accurately replicate the female anatomy and biomechanics, as well as refining testing setups to ensure an accurate representation of the female population.
Addressing the sex gap in vehicle safety tests requires a multifaceted approach. Legislature and regulations must adapt and evolve to prioritize the inclusion of females in safety assessments. It is crucial to ensure that all vehicle manufacturing companies are placing the same importance to the safety of female drivers in their testing procedures. This shift in perspective and approach will contribute significantly to fostering a safer driving environment for females.
Differences in injury severity between males and females also appear to be linked to variations in strength and structural characteristics of soft tissue, particularly regarding ankle injuries, as mentioned in the "Car Collision Lower Limb Injury Biomechanics" section. This poses a challenge in research as ATDs and cadavers prove unsuitable for assessing injuries resulting from soft tissue at this required level of complexity. Moreover, animal testing does not adequately address soft tissue injury differences between human males and females. In all likelihood, complex computational modeling techniques will have to be developed to assist with such injury predictions in frontal collisions to fully understand how these structural differences contribute to injury frequency and severity.[31] Furthermore, a computational model offers the advantage of incorporating muscle activation preceding impact when the driver attempts to brake, enabling a more comprehensive analysis of its impact on injury risk.
Overall, it appears there is an increased need to explore epidemiological shifts in sex differences concerning lower limb injuries in frontal collisions. Perhaps future research could incorporate the THOR-5F, an enhanced version of the 5th percentile female THOR with significant design changes to the leg, ankle and foot for higher biofidelity, and investigate these broader impact differences.[32] Additionally, the variations in injury patterns between sexes are intricately linked to soft tissue and subtle skeletal differences, aspects that might not be discernible through ATD testing. Prioritizing complex collision modeling in future research is crucial, with the hope that it will have the capacity to address these nuanced aspects and help reduce injury risk in car crashes for all.
References
- ↑ 1.0 1.1 Mertz, H.J. (2014). "Anthropomorphic Test Devices and Injury Risk Assessments". Springer EBooks: 83–112.
- ↑ "Hybrid III 50th Male". Humanetics.
- ↑ Williams, E.P.; Mesidor, M.; Winters, K.; Dubbert, M.K.; Wyatt, S.B. (2015). "Overweight and Obesity: Prevalence, Consequences, and Causes of a Growing Public Health Problem". Curr Obes Rep. 4: 363–370 – via Springer.
- ↑ Dotinga, Randy (August 3, 2016). "The average Americans' weight change since the 1980s is startling". CBS News. Retrieved November 30, 2023.
- ↑ Chirag, S. "Shah Development of the THOR-5F crash test dummy FE model and synergy with design support" (PDF). Humanetics Innovative Solutions: Paper Number 17-0244.
- ↑ 6.0 6.1 6.2 6.3 6.4 J. L. Forman et al., “The tolerance of the human body to automobile collision impact – a systematic review of injury biomechanics research, 1990–2009,” Accident Analysis & Prevention, vol. 80, pp. 7–17, Jul. 2015, doi: 10.1016/j.aap.2015.03.004. [1]
- ↑ Jermakian, J. (2022). Improving safety for women requires more than a female crash test dummy. IIHS-HLDI Crash Testing and Highway Safety. Retrieved from [2]
- ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 Dipan Bose, Maria Segui-Gomez, ScD, Jeff R. Crandall, “Vulnerability of Female Drivers Involved in Motor Vehicle Crashes: An Analysis of US Population at Risk”, American Journal of Public Health 101, no. 12 (December 1, 2011): pp. 2368-2373. (Vulnerability of Female Drivers Involved in Motor Vehicle Crashes: An Analysis of US Population at Risk)
- ↑ Larkin, J. (2022, July 7). Women are 47% More Likely to Sustain Serious Injuries In Car Crashes Than Men. AI Online. [3]
- ↑ 10.0 10.1 10.2 10.3 10.4 10.5 Goodwin, Brian & Chirvi, Sajal & Pintar, Frank. (2018). Injury Mechanisms in Traffic Accidents. 10.1007/978-3-319-14418-4_93
- ↑ 11.00 11.01 11.02 11.03 11.04 11.05 11.06 11.07 11.08 11.09 11.10 11.11 Porta, D.J. (2005). Biomechanics of Impact Injury. In: Rich, J., Dean, D.E., Powers, R.H. (eds) Forensic Medicine of the Lower Extremity. Forensic Science and Medicine. Humana Press. [4]
- ↑ Tencer, A. F., Kaufman, R., Ryan, K., Grossman, D. C., Henley, B. M., Mann, F., Mock, C., Rivara, F., Wang, S., Augenstein, J., Hoyt, D., Eastman, B., & Crash Injury Research and Engineering Network (CIREN) (2002). Femur fractures in relatively low speed frontal crashes: the possible role of muscle forces. Accident; analysis and prevention, 34(1), 1–11. [5]
- ↑ White, E.A., Patel, D.B., Matcuk, G.R. et al. Cruciate ligament avulsion fractures: Anatomy, biomechanics, injury patterns, and approach to management. Emerg Radiol 20, 429–440 (2013). [6]
- ↑ (2015). stellate fracture. In Martin, E. (Ed.), Concise Medical Dictionary. : Oxford University Press. Retrieved from https://www.oxfordreference.com/view/10.1093/acref/9780199687817.001.0001/acref-9780199687817-e-9566.
- ↑ 15.0 15.1 15.2 15.3 Ammori, M. B., & Abu-Zidan, F. M. (2018). The biomechanics of lower limb injuries in frontal-impact road traffic collisions. African health sciences, 18(2), 321–332. [7]
- ↑ 16.0 16.1 16.2 Conley, S., Rosenberg, A., & Crowninshield, R. (2007). The female knee: anatomic variations. The Journal of the American Academy of Orthopaedic Surgeons, 15 Suppl 1, S31–S36. [8]
- ↑ Gabrielli, A. S., Gale, T., Hogan, M., & Anderst, W. (2020). Bilateral symmetry, sex differences, and primary shape factors in ankle and hindfoot bone morphology. Foot & Ankle Orthopaedics, 5(1), 247301142090879. [9]
- ↑ Braz, M., & Souto Maior, A. (2021). Functional performance of ankles between male and female practitioners of resistance exercise. Muscle Ligaments and Tendons Journal, 11(04), 704. [10]
- ↑ Steilen-Matias, Danielle. "Does Estrogen cause or prevent ACL injuries in women?". Caring Medical.
- ↑ Wilkerson, R. D., & Mason, M. A. (2000). Differences in men's and women's mean ankle ligamentous laxity. The Iowa orthopaedic journal, 20, 46–48.
- ↑ Hunter, Randee L., et al. «Sex Differences in Human Tibia Cortical Bone Morphometrics from Computed Tomography (CT)». S2-1: Tissue Biomechanics, 2019, [11]
- ↑ 22.0 22.1 22.2 22.3 22.4 22.5 22.6 Bangert, L.G. , et al. “Do Females Have a Higher Risk of Suffering Distal Tibia Fractures in Frontal Car Crashes?” Population Heterogeneity, IRCOBI Conference, Sept. 2023, pp. 244–253. [12]
- ↑ Firemen, M. (2022, July 7). Women are 47% More Likely to Sustain Serious Injuries In Car Crashes Than Men. AI Online. [13]
- ↑ NTHSA. Sex-Based Differences in Odds of Motor Vehicle Crash Injury Outcomes. 2023.
- ↑ 25.0 25.1 25.2 NHTSA. Injury Vulnerability and Effectiveness of Occupant Protection Technologies for Older Occupants and Women. 2013.
- ↑ 26.0 26.1 26.2 26.3 Ye, X. et al. (2015) ‘Analysis of crash parameters and driver characteristics associated with lower limb injury’, Accident Analysis & Prevention, 83, pp. 37–46. doi:10.1016/j.aap.2015.06.013.
- ↑ Wang, Xinyi, et al. “Latent Vehicle Type Propensity Segments: Considering the Influence of Household Vehicle Fleet Structure.” Travel Behaviour and Society, vol. 26, Jan. 2022, pp. 41–56, [14]
- ↑ Bernstein, J. (2023, March 28). SUVs are more popular than ever, but do drivers need all that extra space? | CBC News. CBC News. [15]
- ↑ Sweet, K. (2021, February 12). Smaller Cars May Be Why Women Are More Likely to Suffer Serious Crash Injuries. Retrieved from Insurance Journal: [16]
- ↑ 30.0 30.1 Thomas, P., & Frampton, R. (1999). Large and Small Cars in Real-World Crashes -Patterns of Use, Collision Types and Injury Outcomes. Annual Proceedings / Association for the Advancement of Automotive Medicine, 43, 101–118.
- ↑ Crash test simulations expose real risks. National Science Foundation. (2015, November 12). [17]
- ↑ Thor-AV-5F. Humanetics. (n.d.). [18]