A team of scientists and doctors at the University of Edinburgh are using new laboratory techniques that will lead to improved treatment for patients experiencing problems with joint replacement.
The multi-disciplinary team will try to establish if using molecular techniques can set a ‘gold standard’ to allow doctors to know before surgery is carried out whether a joint replacement has loosened due to wear (aseptic) or infection (septic). This prior knowledge is of critical importance to the surgical team, which uses different treatment, depending on whether infection is present, or absent. For instance, loose hip replacements are usually ‘revised’ in one stage if they are not infected, but in two stages if the loosening has been caused by infection.
Professor Hamish Simpson of the Musculoskeletal Research Unit at the University’s Medical School explained: “Joint replacement surgery has been a major advance in the treatment of arthritis, and more than 100,000 hip, knee, shoulder and elbow joint replacement operations are carried out in the UK each year. As a consequence of an ageing population and the success of these procedures, the numbers are rising. However, failure of the joint replacement occurs in a significant proportion of cases, which then require revision surgery.
“A loose hip causes the patient pain on movement. It is essential to know, prior to the revision operation, whether this loosening has been caused by wear or infection, but current methods for diagnosing joint replacement infection pre-operatively are inaccurate. The surgeon then has to rely on techniques during the operation. The failure to diagnose joint replacement infection has serious consequences for the patient.”
The research team aims to look at the value of employing established molecular techniques (using the polymerase chain reaction-PCR) for diagnosing infection at the pre-operative stage in joint replacement failure. PCR techniques involve taking a sample of tissue from the patient and, under laboratory conditions, establishing whether bacterial DNA is present, which would show there was infection.
Professor Simpson said there might be a high false positive rate with this test, so the research study would have to establish if this method was sufficiently sensitive and specific enough to be useful as a clinical tool.
The study, funded by a grant from the Chief Scientist Office, will last for three years