Characterization of the rate-dependent behavior and failure of human knee ligaments

The structural properties of the four major human kneeligaments were investigated at different loading rates.Bone-ligament-bone specimens of the medial and lateralcollateral ligaments and the anterior and posteriorcruciate ligaments, obtained from post-mortem humandonors, were tested in knee distraction loading indisplacement control. All ligaments were tested in theanatomical position corresponding to a fully extendedknee. The rate dependence of the structural response ofthe knee ligaments was investigated by applying loading-unloading cycles at a range of distraction rates. Ramps to failure were applied at knee distraction rates of 0.016 mm/s, 1.6 mm/s, or 1,600 mm/s. Averages and corridors were constructed for the force response and the failure point of the different ligaments and loading rates. The structural response of the knee ligaments was found to depend on the deformation rate, being both stiffer and more linear at high loading rates. This rate dependence was found to be more pronounced at high loading rates