Hip replacement

Health encyclopaedia - Alphabetical Topic List

| A |

| B |

| C |

| D |

| E |

| F |

| G |

| H |

| I |

| J |

| K |

| L |

| M |

| N |

| O |

| P |

| Q |

| R |

| S |

| T |

| U |

| V |

| W |

| X |

| Y |

The hip joint is a ball-and-socket joint. At least 50,000 hip replacements (arthroplasties) are done in Britain each year. The operation is highly successful in reducing the pain and disability of worn or damaged hip joints, as it replaces both the natural socket (the acetabulum) and the rounded natural ball at the head of the thigh-bone (femur) with artificial parts (prosthetics).

Materials science plays a major part in the design of artificial hip and other joints. The early models, made of stainless steel and Teflon, eventually disintegrated, and many had to be removed. The preference now is for high-density polythene for the socket, titanium alloys for the shaft, and sometimes a separate ball made of an alloy of cobalt, chromium and molybdenum. Some surgeons use a ceramic head.

The hip joint has a wide range of movement and is subject to a range of disorders. Those that most commonly call for joint replacement are osteoarthritis, rheumatoid arthritis, fracture of the neck of the femur (thigh bone), and damage resulting in loss of blood supply to the head of the femur (avascular necrosis).

The operation can be life saving because the enforced lack of movement that follows a hip fracture commonly leads to deep vein thrombosis or a dangerous blockage of the lung arteries by blood clot (pulmonary embolism).

The selective use of a new process called metal on metal (MoM) hip resurfacing has been recommended by the National Institute for Clinical Excellence (NICE). This involves replacing the diseased or damaged surfaces in the hip joint with metal surfaces. NICE advises that MoM should be considered for people with advanced hip disease who would normally be given a conventional hip replacement, but who are likely to live longer than the replacement joint will last (1).