Knee replacement, also known as knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability.
A smooth, durable surface (articular cartilage) on the head of the arm bone and a thin inner lining (synovium) of the joint allows the smooth motion of the shoulder joint.
The hip is one of the body's largest joints. It is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone.