You may be able to choose the type of anaesthetic you're given before hip replacement surgery.
There are 2 options:
- general anaesthetic – where you're asleep during the operation
- a spinal or epidural anaesthesia – an injection into your spine that numbs the lower half of your body
This is often combined with sedation. You won't be aware of your surroundings and you'll have no memory of the surgery.
Your surgeon may sometimes recommend an epidural. There's less chance of causing complications in people with an underlying health condition.
How the operation is carried out
Once you've been anaesthetised, the surgeon removes the existing hip joint completely. The upper part of the thigh bone (femur) is removed and the natural socket for the head of the femur is hollowed out.A socket is fitted into the hollow in the pelvis.
Metal-on-metal hip resurfacing is carried out in a similar way. The main difference is that less of the bone is removed from the femur. Only the joint surfaces are replaced with metal inserts.
The prosthetic parts can be cemented or uncemented:
- cemented parts are secured to healthy bone using acrylic cement
- uncemented parts are made from material that has a rough surface - allows the bone to grow on to it, holding it in place
Most prosthetic parts are produced using:
- high-density polythene for the socket
- titanium alloys for the shaft
- sometimes a separate ball made of an alloy of cobalt, chromium and molybdenum
Some surgeons use a metal ball and socket. In some cases ceramic parts are used, which do not wear out as quickly as plastic.
There have been recent reports about metal-on-metal hip replacements causing complications.
The hip replacement operation has become a routine procedure. But as with all surgery, it carries a degree of risk.
There are more than 60 different types of implant or prosthesis. The options are usually limited to around 4 or 5. Your surgeon will tell you the type they think would suit you best.
Your surgeon will also be able to discuss any concerns about metal-on-metal replacements.
Minimally invasive hip replacement
In conventional hip replacement, a relatively large cut of 20 to 30cm (8 to 12 inches) is made in the skin. This is performed above the hip, letting the surgeon gain access to the hip joint.
A new technique is called minimally invasive hip replacement. This uses a smaller cut of around 10cm (4 inches). Specially designed instruments are then passed through the incision to perform the surgery.
Minimally invasive hip replacement is as safe and effective as conventional surgery. There is an added benefit of causing less pain after surgery.
Access to this type of specialised treatment is limited. It could involve waiting much longer for treatment.