The suitability of Synbone^® as a tissue analogue in ballistic impacts

Knowledge of material behaviour under impact is of key importance to understand ballistic impact events on tissue. Bone—with its complex underlying microstructure—is no exception; the microstructural network in bone is not only crucial to its integrity, but also provides a pathway for energy dispersion upon impact (Piekarski in J Appl Phys 41:215–225, 1970). Synbone^®, a Swiss-made polyurethane bone simulant, has been considered as a potential bone analogue, particularly for cranial structures (Smith et al. in Leg Med 17(5):427–435, 2015; Riva et al. in Forensic Sci Int 294: 150–159, 2019). This study focused on long bone models and cylinders available from Synbone^®, with the aim of determining their efficacy for use in ballistic testing and recreation. Comparisons were made between porcine bone and multiple Synbone^® models regarding projectile energy loss and damaged surface area using high-speed video and high-resolution photography. CT and reverse ballistics techniques were also used as diagnostic tools. A significant correlation was made between real bone and Synbone^®’s ballistic cylinders in all aspects of this study; however, it was observed that osteoporotic cylinders and anatomical models differ significantly in their reaction to impact. Consequently, the use of Synbone^® as a ballistic target simulant—particularly when legal or practical accuracy is essential—will need to be treated carefully, giving due attention to these limitations.