Final answer:
During a total hip arthroplasty, the acetabulum of the pelvis is reshaped to fit a new artificial femoral head, helping restore joint function. The ilium forms the superior part of the hip bone. Neither the patella nor the tibia is involved in this surgery.
Step-by-step explanation:
In a total hip arthroplasty, or hip replacement surgery, the component that is reshaped is the acetabulum, which is part of the pelvis. The femoral head, or 'ball' of the patient's femur, is replaced with an artificial head that fits into a new cup that has a hard plastic-like lining. This provides a new, smooth surface for the joint, which is necessary when the natural cartilage has worn away or been damaged, as the hip is a ball (end of the femur) and socket (part of the pelvis) joint. The procedure restores mobility and relieves pain in patients with damaged or arthritic joints.
The component which forms the superior part of the hip bone is the ilium, identified as option (a) in the reference information. The femur and pelvis form the hip joint at the proximal end, and it is this joint that is reconstructed during hip replacement surgery. It is important to note that the patella or the tibia are not reshaped during this procedure as they are components of the knee joint, not the hip joint.