Abstract: A knee ligament testing device (10) is disclosed for use in testing the ACL ligament of the knee. The device includes a force application arm (12) and reference arm (18) which are hinged at a pivot joint (20). A predetermined maximum force can be applied to the force application arm (12) by exerting force on a torque limiter (26) inserted in an aperture (38) in the force application arm (12). The torque limiter (26) insures that the identical force will be applied on a leg for every test to insure reproducibility and prevents the application of excessive force to the leg. Displacement of the tibia relative to the femur is sensed by movement of an inner tube (56) relative to an outer tube (54) which is translated into rotational movement of an input shaft through potentiometer (66). The change in resistance in the potentiometer (66) is analyzed and converted to a linear measurement which is displayed on a display (72).