Abstract: A device for evaluating the integrity of the patella femoral joint measures movement of the patella in response to a lateral force applied against the patella of a flexed leg supported in a relaxed position. The device includes a measuring instrumentality which is positionable against the patella to measure the linear displacement of the patella in response to the lateral force. The magnitude of the applied force is correlated with the degree of leg flexion and the linear displacement of the patella to indicate the health and condition of tissues in the knee which resist dislocation of the patellofemoral joint and which promote alignment of the patella within the joint.

Abstract: The present invention is an ergometer for isometrically exercising one or more leg muscles of a patient undergoing rehabilitation of the knee joint following knee ligament surgery. The ergometer has an upper leg restraint and a lower leg restraint which are positioned on the leg above and below the knee respectively. The leg restrains are maintained in a fixed position relative to the leg by a rigid crossbar and a bolster positioned behind the knee. Exercise of the hamstring or quadriceps muscles is performed by isometrically contracting the desired muscles while the knee is at an extension angle which does not stress the ligament under repair. Muscle contraction can be artifically induced by an electrical stimulator, which in concert with a closed-loop control system, effectively regulates the exercise level.

Abstract: A device for measuring displacement of the tibia from a stationarily held patella in response to a specific anterior/posterior force applied on the tibia comprises a reference member which establishes a fixed reference line extending from the patella to a region located distally on the tibia. A measurement member has one end hingedly attached to the reference member and its other end slidingly attached to a tibia paddle which rests on the proximal region of the tibia. A rotatable yoke on the tibia paddle has one prong which rests on the lateral flare of the tibia while another prong of the yoke rests on the medial flare of the tibia.

Abstract: A method and instrument for skeletal referenced isometric positioning and tensioning of a ligament graft, particularly during knee surgery involving the anterior cruciate and the posterior cruciate ligaments. The graft is extended from one fixation site and attached to a sled slidably carried by a frame which is skeletally mounted to the other fixation site. A thumb nut and lead screw assembly on the skeletally fixed frame is operative to compress a spring in the sled and move the sled in a direction effective to tension the graft. Isometry is achieved when the relative positions of the frame and sled indicate constant graft tension and displacement through the entire range of passive knee flexion. The sled can be fixed relative to the frame for evaluation of joint laxity.

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.