This chapter concentrates on the reconstruction of knee ligaments with specific reference to the anterior cruciate ligament (ACL). This is because the knee is the joint most vulnerable to ligamentous injuries and the ACL is the most frequently injured. The ACL is attached to the medial side of the intercondylar area of the tibia and the lateral side of the intercondylar notch of the femur. The medial collateral ligament strengthens the medial aspect of the capsule. It is a broad, flat band nearer the back than the front of the joint. It runs from the medial femoral condyle to the medial condyle and surface of the shan of the tibia. Laboratory measurements on various ligaments have been carried out to determine their mechanical properties. Where human ligaments are concerned, more attention has been given to knee ligaments, these being the most vulnerable to injury and most needing reconstruction.