In order to understand what a total hip replacement is, it is necessary to understand how a healthy hip works. The hip is a ball and socket joint. The “ball” is at the top of your femur (thigh bone) and the “socket” is at the bottom of your pelvis. There is cartilage that covers the head of the femur. This allows the ball to move easily and smoothly in the socket. With the help of the muscles surrounding the hip, you are able to walk easily and without pain.
An unhealthy or painful hip usually results from a wearing away of the cartilage. Without the cartilage present, there is no protection between the bony surfaces of the ball and socket. These two bony surfaces become rough and begin grinding against each other. This causes pain that results in stiffness and discomfort during movement.
Conditions that can lead to an unhealthy or painful hip include:
- Rheumatoid arthritis—A chronic disease affecting primarily the lining of the joint resulting in destruction and deformity. The cause of rheumatoid arthritis is unknown.
- Osteoarthritis—Affects the joint surfaces of weight bearing joints. Although the exact
cause is unknown, it is believed to be caused by abnormal wear and tear to the joint
surfaces. Other factors that may contribute to osteoarthritis include age, sex, heredity, and obesity. - Other causes of degeneration of the hip include previous hip injury, metabolic bone disease, and abnormalities of growth.
If your surgeon recommends a total hip replacement, he or she will choose the best artificial hip (prosthesis) for you. This prosthesis is usually made up of 4 components—a cup, liner, ball, and stem. Different types of materials are used to make these components. The cup and stem may be cemented to the bone or porus coated, which allows bone to bond directly to the implant surface.
Ask your surgeon if you have specific questions about your surgery or the types of implants available to replace your hip. The artificial hip will act almost like a healthy hip and should allow for walking with ease and without pain.