Hip replacement surgery. Image 17 of 30. Femoral implant in place in the femur (upper leg bone). It is cemented inside the femoral shaft and will have a ball added to the protruding part. The ball will articulate with an implant in the pelvis and form the new hip joint. This surgery is usually performed in response to arthritis, degeneration of the joints, and restores mobility to people who would otherwise be incapacitated by pain and unable to move freely. For a sequence of images showing the full surgery, see M551/340-369. For a sequence showing the operation on the femur, see images M551/344-359.