Elasticity and Tensile Strength of the Anterior Cruciate Ligament in Rabbits as Influenced by Training

The effects of training in a running machine were studied on nineteen rabbits while seventeen of the same stock were used as controls. The rabbits were at the start of the training period about three months old and the mechanical tests were performed forty weeks later. Tensile strength and elasticity tests were performed on anterior cruciate ligaments from their knee joints utilizing the femur and the tibia as fixture points. It is concluded that the weakest point in the system of tibia-ligamentum cruciatum anterius—femur is one of the bony attachments and most often the tibial one. The energy required to break the system is increased by training and so are the maximun load and the deformation at that point. All these phenomena can be accounted for by strengthening of the bones. The elasticity tests, however, show a larger load-relaxation phenomenon in the ligaments from the trained animals and it occurs with a higher speed, indicating altered viscous properties. It is concluded that these changes must be qualitative changes occurring in the ligamentous tissue.