Foot–Ankle Fractures and Injury Probability Curves from Post-mortem Human Surrogate Tests

Abstract

This purpose of this study was to replicate foot-ankle injuries seen in the military and derive human injury probability curves using the human cadaver model. Lower legs were isolated below knee from seventeen unembalmed human cadavers and they were aligned in a 90-90 posture (plantar surface orthogonal to leg). The specimens were loaded along the tibia axis by applying short-time duration pulses, using a repeated testing protocol. Injuries were documented using pre- and post-test X-rays, computed tomography scans, and dissection. Peak force-based risk curves were derived using survival analysis and accounted for data censoring. Fractures were grouped into all foot-ankle (A), any calcaneus (B), and any tibia injuries (C), respectively. Calcaneus and/or distal tibia/pilon fractures occurred in fourteen tests. Axial forces were the greatest and least for groups C and B, respectively. Times attainments of forces for all groups were within ten milliseconds. The Weibull function was the optimal probability distribution for all groups. Age was significant (p < 0.05) for groups A and C. Survival analysis-based probability curves were derived for all groups. Data are given in the body of paper. Age-based, risk-specific, and continuous distribution probability curves/responses guide in the creation of an injury assessment capability for military blast environments.

Mapping the Risk of Fracture of the Tibia From Penetrating Fragments

“…The modified Winquist-Hansen classification was chosen to score the fracture outcomes as it is the most suitable classification for this type of penetrating injury to the bone (Nguyen et al, 2020). Left censoring was used in the statistical analysis for impacts that resulted in fracture as the minimum impact velocity required to generate that fracture (i.e., time to failure) could not be measured; this is known to be a conservative statistical approach (Breeze et al, 2013b;Yoganandan et al, 2016a). Interval censoring was used to account for the reuse of uninjured samples after one low velocity impact; reusing samples helps optimizing the number of samples required, accounting for 20% of all tests in this study.…”

Gelatine Backing Affects the Performance of Single-Layer Ballistic-Resistant Materials Against Blast Fragments

“…To obtain the three values of V 50 in categories (a)-(c), a risk curve was generated for each category using Weibull survival analysis (Quenneville et al, 2011;Yoganandan et al, 2016) conducted with the NCSS statistical software (Utah, United States). The Weibull regression model was used with impact velocity of the FSP as the predictor variable; tests were classified as left censored if resulting in perforation/penetration and as right censored otherwise.…”

A Comprehensive Review of Medical Imaging Equipment Used in Cadaveric Studies

“…X-ray studies were also completed on the ankles of cadavers prior to load testing on the lower legs, then the ankles were re-X-rayed to assess structural changes [ 6 ].…”