Hip Prosthesis Types
Hip replacement is a very successful procedure, having some of the highest quality of life improvements of all medical interventions. Over 50,000 episodes of hip replacement surgery are performed every year in the UK, with this technique relieving pain and restoring function to a large number of mostly elderly people every year.
Cemented Total Hip Replacement
This is the gold standard hip replacement surgery, used overwhelmingly for elderly people with hip arthritis. Developed mainly by Sir John Charnley in the UK, hip replacement has been continually improved since the late 1960s and has very good long term published results which show successful survival of the implants over fifteen years or more in the vast majority of patients.
The Exeter, Stanmore and Charnley types of total hip replacements are examples of UK designs with good long term results, although there are many others. Pressurised cement techniques and impaction bone grafting have led to great reliability of hip replacement over many years.
Uncemented Hip Replacement
Uncemented hip replacements are another of the types of hip replacement joints which have been developed to try and get round the perceived problems with cemented joints. Problems include loosening of the junction between the cement and the bone leading to the joint needing to be revised. However, modern techniques have minimised these problems.
Uncemented joints are press fitted into the prepared femoral canal and socket and may be metal on metal or metal on plastic joints. The surfaces of the components are covered in a porous coating which is intended to encourage the growth of bone up to and into the component. Uncemented replacements are often used in younger people to avoid the difficulties of re-doing the joint when it inevitably occurs.
Hip resurfacing has been developed primarily in Birmingham, UK and presents itself as an alternative to total hip replacement with cement. As the arthritic joint surfaces are replaced by artificial surfaces made of metal, this meets the hip arthroplasty definition.
In hip resurfacing, the amount of bone removed from the socket and the femoral head is very small and the surfaces are replaced by metal hemispherical ones. This keeps the bone of the upper femur which may be important if further operations have to be performed. Proponents of this design say that patients are not so limited as to what they can do, dislocation is less likely and more bone stock is preserved than other types of hip replacement.