MODEL RELEASED. Hip replacement surgery. Image 6 of 9. Implant inserted into a hole drilled in the femur (thigh bone) during hip replacement surgery. It is held in place by cement (white). A metal ball will be placed over the head of the implant. The ball will be inserted into a prosthetic socket in the pelvis and articulate in exactly the same way as a normal hip joint. Joints may need to be replaced after injury, disease or deformity. This hip is being replaced because of congenital hip dysplasia, a condition where the hip joint does not fit together properly, causing it to dislocate frequently and to become worn. For a sequence showing the operation see M551/418-M551/426.