Abstract: A tibia-referenced system for objectively testing the integrity of the anterior and posterior cruciate ligaments of the knee with passive drawer, active drawer, and end point tests. Two simplified forms of the invention embody an elongated reference arm with a distal end pad that is fulcrumed against a distal region on the tibia and a proximal reference pad that rests on either the tibial tubricle or patellar bone structure, while a displacement indicator rod slidably mounted on the arm carries another proximal reference pad that rests on the other of these two bone structures adjacent the knee joint.