Chen, M.M., female, 76 years old. Bilateral knee osteoarthritis and knee inversion. After bilateral knee surface replacement, the patient’s pain was relieved and she was able to live a happy and dignified life in her old age. Pre-operative standing film of both lower limbs showed severe inversion deformity of the left knee Pre-operative orthopantomogram of both knees showed severe degeneration of the joint The posterior ankles of both knees were also severely worn at 45 degrees of flexion Post-operative orthopantomogram of both knees showed good position of the prosthesis, and the force line of the lower limbs was restored One month after surgery, the prosthesis of both knees were in good position