The goal of the proposed research is to better understand the mechanical factors in surgical repair procedures for chronic anterolateral insufficiency of the knee, for which the repair requires an anterior cruciate substitute to be established. Experiments will be run on cadaver knee specimens in which ligament forces will by measured by buckle force transducers on the four major knee ligaments, and a six degree-of-freedom goniometer system will be used to measure 3-dimensional knee motion, when the knee is subjected to a wide variety of external load directions. Normal knees, knees with a simulated anterolateral injury, and knees repaired by one of eight procedures will be tested in an identical manner. Theoretical ligament lengths, and hence, loaded ligament states, will be predicted using already developed theoretical knee models, with the measured 3-D motion as input. The influence of repair insertion location will be studied both theoretically and experimentally. The normal and repaired knees will be compared on the basis of anterior cruciate or substitute force magnitude, joint laxity, and load sharing by the other ligaments.