MODEL RELEASED. Knee replacement surgery. Image 4 of 10. Surgeons removing excess cement after fitting an implant to the tibia (shin bone) of a patient during knee replacement surgery. The skin and soft tissues have been peeled back from the knee to expose the bones of the joint. Another implant will be fitted to the femur (thigh bone, right of tibia) to create a hinge joint that articulates in exactly the same way as a normal knee joint. Joints may need to be replaced after injury, disease, for example arthritis, or deformity. This knee is being replaced because of a valgus instability, which causes an inward facing knee. For a sequence showing the operation see M551/397-M551/406.