What is a hip prosthesis?

A hip prosthesis is an artificial joint used to replace all or part of a damaged hip during a hip replacement procedure. The characteristics of the materials used in this type of prosthesis mimic the ball-and-socket action of a natural human joint. Hip replacement is usually recommended in cases of osteoarthritis or rheumatoid arthritis.

What is a hip prosthesis made of?

The implant can be made from strong plastic, typically polyethene, ceramic and various metals such as:

• stainless steel
• cobalt
• chromium
• titanium alloys

Which part of the hip is replaced?

The hip joint is made up of two main parts. One or both parts can be replaced during surgery:

• The hip socket (a part of the pelvic bone called the acetabulum)
• The upper end of the femur (called the femoral head)

What is a hip prosthesis made of?

The new hip that will replace the old hip is made up of the following parts:

• An acetabular cup, usually made of strong metal
• An insert, which fits inside the cup or acetabulum, is usually made of plastic, but some surgeons are now testing other materials such as ceramics. The insert allows the hip to move easily
• A metal or ceramic sphere that replaces the round (upper) head of the femur
• A metal stem that is attached to the femur to give more stability to the joint

What are the different types of hip prostheses?

Metal-on-metal

The socket and the ball components are both made of metal.

Polyethene and metal on polyethene

The socket or the acetabular liner is typically made of plastic with other components made of metal and covered in plastic.

Ceramic on metal, polyethene or ceramic

Ceramic is often used with metal or plastic when the patient is allergic to certain metals. Although ceramic in the past was considered too fragile, ceramics parts are nowadays believed to live longer than metal parts.

When is a hip replacement needed?

You may need a new hip if your natural hip joint is worn or damaged so that your ability to move around is reduced. Most people that undergo a hip replacement are suffering from osteoarthritis, however, other conditions can lead to needing a hip prosthesis, such as:

• rheumatoid arthritis
• hip fractures
• septic arthritis
• bone dysplasia

How long does a hip prosthesis last?

Most hip replacements last for at least 15 years, however, this depends on the different brands and type of hip prosthesis.

Which specialist performs a hip replacement?

A specialist that carries out a hip replacement is an orthopaedic surgeon.