Abstract
The effects of dynamic loading rate on the load sharing of passive and active subsytems of the spine were evaluated using a validated viscoelastic finite element (FE) model of a L2-L3 motion segment. Both the force controlled and hybrid force-rotation controlled simulations were performed to best simulate the in-vivo loading conditions. The stiffening response of motion segement at higher loading rate was predicted by both simulation strategies, while the interpretation of the hybrid simulations was much easier due to decoupling of the confounding interactions of load, posture and loading rate. The results collectively indicate that the loading rate markedly effects the distribution of stress/strain in the tissues and reduces the margin of safety of the spine. The results should be used in developing a better biomechanical basis for considering the role of trunk speed as a risk factor for low back disorders.
