Evaluation of knee injury threshold in pedestrian–car crash loading using numerical approach

Abstract The present work evaluates the sensitivity of various loading parameters to the injury response of the human knee joint in pedestrian–car impact loading using a numerical model. The knee joint from a previously developed finite element lower limb model was validated against published postmortem human subject test results for stiffness and injury response. Previous studies have reported injury threshold for the knee joint based on validation with whole limb experimental tests in pure bending and shearing. The goal of the present study is to ascertain the validity of such injury thresholds when evaluated for isolated knee joint specimens, and furthermore, performing a sensitivity analysis by altering various loading parameters such as valgus bending rate, torsional degree of freedom and amount of lateral shear displacement. Findings of this study suggest that the threshold values for the cruciate ligaments are underestimated, attributed to the non-homogenous strain distribution of the ligaments which is not characterized in experimental results. Finally, the factors critical to injury of each major knee ligament have been described with the injury parameters recorded in each case. The reported injury parameters in the present study can be applied to modify the pre-existing injury thresholds incorporated in numerical models and mechanical surrogates, and design better countermeasures aimed at ameliorating pedestrian lower limb injuries.