"Many more people facing surgery for knee problems would be better off with a partial rather than total knee replacement which should allow them to recover faster say experts. Partial replacements are also cheaper say researchers from Oxford University. The NHS https however needs to get the support of surgeons many of whom rarely carry out the less invasive procedure. Partial replacements also known as unicompartmental replacements are suitable for people who have arthritis in just one side of the knee usually the inner. They can be carried out with a smaller incision using minimally invasive surgery but they are only suitable for people whose ligaments inside the knee are strong. Researchers from the Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Sciences NDORMS https publishing in the BMJ Open httpbmjopen.bmj.com journal found that the less invasive procedure was being used less than it could be. The main reason for the surgery is osteoarthritis. About half of all patients should be suitable for a partial replacement but an analysis of data routinely collected by the National Joint Registry showed that of  knee replacements undertaken in  only  were partial. The main strength of this study is that we were able to use real data from very large numbers of people about their actual operations their GP visit and their own reported quality of life outcomes in a way that is not always possible said Dr Rafael PinedoVillanueva the colead researcher and NDORMS senior health economist who is funded by the National Institute of Health Research Oxford Biomedical Research Centre httpsoxfordbrc.nihr.ac.uk and the Medical Research Council.  This has allowed us to provide strong proof that partial knee replacements are both better for patients and cheaper for the NHS. Whether people had a partial or total replacement varied by surgeon as did the success of the operation the researchers discovered. Those surgeons who carried out more partial replacements had better outcomes from them than surgeons who did fewer. This is an important finding said colead researcher Prof David Murray. If surgeons aim to use partial knees in a quarter or more of their knee replacements this will substantially improve the results of knee replacement and will save money. In addition more partial knee replacements will be done and more patients will benefit from this procedure. Ed Burn first author of the paper said they needed to get surgeons on board. For patients and the NHS to see the benefits of partial replacements we need the buyin of surgeons who would need to feel comfortable performing a greater proportion of their knee replacements as partials he said. If we see surgeons carrying out this procedure more often the proportion of knee replacements that are partials would increase from the current figure of  and we would see an increase in future economic and population health gains."