At normal conditions, one of the most important knee stabilizers is the Anterior Cruciate Ligament (ACL).Seven pig knees were subjected to a 700 N compressive load at three different flexion angles (70°, 55° and 40°) using a universal testing machine MTS Bionix 515.11.Contact pressure, contact area and peak force were obtained for healthy knees and ACL hyper-extension injury was induced to the knee by a load in the posterior side of the tibia with the knee at full extension until the ligament failed.The obtained results showed statistically significant differences (p<0.05) for the contact pressure for the highest angle evaluated vs all the other angles in an injured knee.To the contact area with some little differences.Lastly, for the peak force statistically significant differences were found in almost all the conditions denoting the importance of the ACL as a primary stabilizer.The present study sought to determine the contact mechanics on healthy and ACL ruptured knees.