Advanced biofidelic headforms for high fidelity re-enactment of real-world head impacts in cricket

Cricket presents an interesting opportunity for head injury research. The head injuries that occur do so at a consistent rate, in a predictable position on the pitch, and with reliable access to verified reports of the outcomes. Methods were developed to use videos of head impacts in cricket to establish ball velocity, head orientation and impact location required to re-enact real-life head impacts where the real-life outcome was known. The method for determining impact characteristics was validated against computationally simulated validation data and one example of Hawkeye data. The outcome was an uncertainty of ± 0.75 m/s in velocity magnitude, ± 6o in inbound vector angle and ± 44 mm in impact location. Velocity uncertainty was comparable to the ball cannon uncertainty. Head orientation uncertainty was about three-fold greater than the headform positioning uncertainty but equal to the uncertainty that might be expected from a machine learning algorithm of the time. Impact location was just over seven-fold greater than physical headform positioning uncertainty. This experimental setup this was significantly more representative for real-life impacts than anything previously published for short duration impacts.

Literature showed that the headforms used in most impact studies have gross simplifications of human anatomy. It was hypothesised that the highly simplified headforms are not capable of exhibiting the phenomena most closely correlated to mTBI since they don’t have a biofidelic brain. In response, two headforms were developed. The first novel headform (denoted LU 1.1) was a semi-simplified headform based upon the previous work of Stone (2019). LU 1.1 had a biofidelic skull and soft tissue layer. It had a geometrically accurate cranial cavity which was filled with mechanically representative Sylguard 527 brain material. A second more advanced headform (denoted LU 2.0) was developed with a separately moulded brain geometry within the cranial cavity. LU 2.0 had biofidelic falx cerebri, falx cerebelli and tentorium cerebelli membranes, and the subdural space was filled with artificial cerebrospinal fluid. One area that LU 2.0 represented significant progress was the development of an advanced chemical welding method to facilitate the placement of a biofidelic brain within the cranial cavity without compromising the biofidelity of the skull. [Continues ...]