After reviewing thousands of case studiesgoing back 25 years across six countries, generalizable survival data is nowavailable for the first time to estimate how long hip and knee replacements arelikely to last.
The findings of researchers, funded by theNational Joint Registry, from the Musculoskeletal Research Unit at theUniversity of Bristol have been published in The Lancet. These findings show that eightout of ten total knee replacements and six out of ten total hip replacementswill still be in place after 25 years.
"Over two million hip and kneereplacements have been performed in the UK since 2003 and patients often askclinicians how long their hip or knee replacement will last, but until now, wehave not had a generalizable answer." said lead author Dr Jonathan Evans,National Joint Registry Research Fellow and Clinical Research Fellow at theBristol Medical School; Translational Health Sciences (THS), based at SouthmeadHospital.
"Previous studies have been based onmuch smaller samples. At best, the NHS has only been able to say how longreplacements are designed to last, rather than referring to actual evidencefrom multiple patients' experiences of joint replacement surgery. Given theimprovement in technology and techniques in the last 25 years, we expect thathip or knee replacements put in today may last even longer."
Hip and knee replacements are two of the mostcommon and effective forms of surgery. Yet even in the best-case scenarios,they will ultimately fail due to processes such as infection, fracture, normalwear and tear or reaction to wear particles. In many of these cases, patientsrequire revision surgery which is more prone to failure, associated with poorerfunction and more expensive than primary surgery.
Knowing how long a hip or knee replacement islikely to last is therefore key for patients, orthopedic surgeons andcommissioners when deciding whether surgery should be done and when. This willbecome increasingly relevant to more people given the longer life expectancy ofa growing population.
A hip replacement principally consists of twocomponents, one that replaces the ball and another that replaces the socket.There is variation in how these parts are fixed to the bone, as well as in thematerials used to create the bearing (contact) surface. There are two maintypes of knee replacement used in the UK. A total knee (TKR) replaces all thepatient's own joint surface whereas a unicondylar knee replacement (UKR) onlyreplaces the damaged part of the knee. There is considerable variation in howlong different designs of hip and knee replacements last and these factors wereaccounted for in Bristol's study.
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