I suggest decomposing the knee joint system into a more simple form drawing comparisons between the cartilaginous surfaces and springs. In this way you may look the sesamoid structure as a solid mass surrounded by a series of springs upon which difference forces are acting depending on the source of perturbation, although this alternative may only be useful if you wish to only analyze the restitution response of the cartilage during the landing. For the bending instances of the leg and forefoot, I suggest a simple physics simulating software (Bender for example), it should show the behavior of the torque over the selected joint.