Chapter 118 - Total hip replacement

Summary

The hip joint is a constrained ball and socket joint capable of withstanding repeated forces in excess of ten times body weight. The articulating surfaces of the femoral head (the ball) and the acetabulum (the socket) are covered with articular cartilage which allows smooth and painless motion. Pain, stiffness, and declining function due to cartilage and bone damage in the hip joint are the primary indications for total hip arthroplasty. Most commonly, these symptoms are the result of osteoarthritis, but can also occur with inflammatory arthritis (e.g., rheumatoid arthritis), bone death (e.g., avascular necrosis) or the sequelae of traumatic injury (e.g., previous fracture). It is now recognized that most cases of hip osteoarthritis are a result of subtle variations in the shape of the femoral head and/or acetabulum. These variations result in hip impingement (abnormal contact forces across the joint that eventually result in destruction of articular cartilage).

When the symptoms of hip arthritis are no longer responsive to conservative measures including medication and reduction in hip joint force (e.g., weight loss or use of a cane), total hip arthroplasty may produce dramatic improvements in pain management, function, and quality of life. The operation is performed through an incision over the outside of the hip. The joint is exposed and an osteotomy (bone cut) in the femoral neck allows removal of the femoral head from the acetabulum. The acetabulum is prepared to accept a hemispherical metal socket. A hemispherical socket liner is then snapped into the socket. The hollow canal of the femur bone is prepared to accept a metal stem. A ball that perfectly matches the shape and size of the liner of the socket is attached to the top of the stem. The soft tissues around the hip are then repaired and protected while they heal.