How do Cats Resist Landing Injury: Insights into the Multi-level Buffering Mechanism

When humans jump down from a high position, there is a risk of serious injury to the lower limbs. However, cats can jump down from the same heights without any injury because of their excellent ability to attenuate impact forces. The present study aims to investigate the macro/micro biomechanical features of paw pads and limb bones of cats, and the coordination control of joints during landing, providing insights into how cats protect themselves from landing injury. Accordingly, histological analysis, radiological analysis, finite element method, and mechanical testing were performed to investigate the mechanical properties, microstructure, and biomechanical response of the pads and limb bones. In addition, using a motion capture system, the kinematic/kinetic data during landing were analysed based on inverse dynamics. The results show that the pads and limb bones are major contributors to non-impact-injuries, and cats actively couple their joints to adjust the parameters of movement to dissipate the higher impact. Therefore, the paw pads, limb bones, and coordinated joints complement each other and constitute a multi-level buffering mechanism, providing the cat with the sophisticated shock absorption system. This biomechanical analysis can accordingly provide biological inspiration for new approaches to prevent human lower limb injuries.