The five cases of the unstable knee due to old rupture of the anterior cruciate ligament and the medial collateral ligament were operated by following method;
1) the tendon of the semitendinosus muscle was cutted out at proximally about 15cm length,
2) a hole was penetrated from the medial condyle of the femur—passed through the intercondyloideal fossa and further through the articural surface of the tibia—to part of the tuberositas tibiae cutted off previously,
3) the tendon as above mentioned was inserted in this hole and pull out to the tibia,
4) the tendon was tightly sutured and fixed to entrance and exit of this hole.
Satisfactory results were obtained in our all cases.
