METHOD FOR SETTING KNEE JOINT PROSTHESES Russian patent published in 2002 - IPC

FIELD: medicine. SUBSTANCE: method involves bending knee joint by 90 deg and forming canal in bone along the anatomical axis of the femur. Intramedullary nail is introduced into the canal and valgus angle relative to the nail axis is formed by using valgus angle guide device with its following adjustment. Then, osteotomy guide device is set to determine femur condyles resection level. Distal femur osteotomy is carried out in the plane set in perpendicular to the valgus angle direction corresponding to the determined level. Measurement template with openings is applied to and fixed on the sawn surface of the femur to determine endoprosthesis femur part size. Two canals are formed in the femur through the template openings for fixing a resection template or the femur part. Then the resection template is fixed by means of these canals on the distal sawn surface, anteroposterior femur portions resection is performed and angular resections of the sawn surfaces are done to make their control examination later on. Characteristic features are related to setting tibial part manufactured as metal platform with a hole and pedicle and polyethylene endoprosthesis platform mountable between the femoral and tibial parts. When making intermediate resection of the proximal part, the crus is positioned at an angle of 90 deg to the table surface and fixed in the position protruding forward. The intermediate resection is carried out at a depth set in correspondence to the condyle that is destroyed most of all in the plane set in perpendicular to the anterior crus surface. The so produced saw cut surface is adjusted in extended knee joint state by setting femoral part metal TEST-prosthesis on the saw cut surface between which and tibial saw cut surface one of the polyethylene templates is placed. Polyethylene template height is selected by measuring the degree of lateral ligament tension. The height is defined as sum of tibial part metal platform height and polyethylene endoprosthesis platform height and corresponds to one of the sizes in the range of 9.5-17.5 mm. Final tibia resection is carried out on the basis of adjustment results. Then tibial part sizes are selected by means of template with an opening on the cortical surface under condition of the external template surface fully covering cortical surface of the produced saw cut. The template is to be fixed on the saw cut surface, the crus is moved forward and bed is formed in the tibia through the opening for the pedicle to be placed there. Flexion and extension in the knee joint and final level of ligaments tension are tested by applying metal TEST-prostheses of femoral and tibial parts. Then the corresponding endoprosthesis parts are fixed on the femoral and tibial saw cuts. EFFECT: enhanced physiological match to living knee joint properties. 13 dwg