Improving whiplash simulation accuracy from the bottom up: from individual musculotendons to the entire neck

• Applicants: Dr. Matthew Millard; Dr. André Tomalka
• Subject Area: Orthopaedics, Traumatology, Reconstructive Surgery ; Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 540349998

Whiplash injury from car accidents affects hundreds of thousands of people in Europe annually, can lead to chronic pain, and is expensive to treat. Autonomous driving may introduce an additional risk of whiplash injury due to novel seating positions. While anthropomorphic test devices can be used to assess the risk of injury for a prototype, safety can only be assessed using simulation during the early phases of design. Assessing the risk of whiplash injury using simulation is challenging because conventional muscle models do not accurately predict the forces developed by muscle as it is activated, lengthened, and injured during a vehicle accident.We propose to conduct unique experiments so that the effects of injury on the passive and active properties of muscle can be modelled. Different structures within an actively lengthened muscle can develop large forces and cause injury. During relatively large and slow stretches, a protein called titin can develop large forces. In contrast, during very rapid stretches, cross-bridges can develop large forces. Accordingly, we plan to measure how muscle properties are affected by long stretches that cause injury, a process influenced by titin. In addition, we also plan to characterize better how muscle length and contraction velocity affect the stiffness and damping of muscle, a process dominated by cross-bridges. We plan on making the data and models publicly available for finite element crash simulations and multibody biomechanics simulations to ensure that others can build upon our work. To help guide future experiments and models, we will contribute a benchmarking simulation library that compares simulated muscle against experimental data.To improve the accuracy of whiplash simulation, the flexibility, strength, and reflex response of the entire neck model should match experimental data closely. The strength of existing neck models has been assessed in flexion and extension, and the reflex responses of some muscles near the surface have been assessed. However, it remains to evaluate the flexibility of the neck, the strength in the remaining directions, and to examine the reflex responses of deeper muscles. We plan on carrying out these detailed benchmark simulations using experimental data from the literature to see how closely neck models resemble a living person's neck.Although we are focusing on whiplash injury specifically, the experimental and modelling work we plan to do will have broader applications. The experiments and modelling of muscular injury will directly apply to simulating muscular injury in general. The muscle models we will contribute to the public domain can be used for simulating any activity in which muscle is actively lengthened, from walking and running to landing from a jump. Finally, our planned measurements, data, and models will also contribute directly to basic science and may shed light on why muscle becomes weaker at short lengths.

• DFG Programme: Research Grants
• International Connection: Canada
• Cooperation Partner: Professor Dr. Walter Herzog