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Prevent Problems Caused by Infected Knee Prosthetics
December 20, 2010
Source: Lund University
As the population grows older and heavier--both factors in the development of osteoarthritis--the number of people who undergo operations to get prosthetic knee joints is increasing. The number of knee replacement operations has increased by 9 percent a year in recent years.
"So if 1-2 percent of the operations lead to bacterial infection, then the need for revision - re-operation - will also increase", says Anna Stefánsdóttir.
This process requires two operations. First, the old prosthesis is removed and temporarily replaced with bone cement while the patient is treated with antibiotics to eradicate the infection. Six weeks later, the doctor performs a second operation to insert the new prosthesis.
In some cases, when it is not possible to insert a new prosthesis, patients are treated with an arthrodesis, or removal of the prosthesis. This leaves the leg without a real knee joint, often confining the patient to a wheelchair. In exceptional cases the infection leads to amputation.
Anna Stefánsdóttir has reviewed almost 480 cases of revision knee replacement between 1986 and 2000.
"Over time more patients have received a new knee prosthesis and fewer are treated with an arthrodesis, but still there are many people who do not get rid of the infection. Other studies show that those who have to have a second operation because of an infection are less satisfied than those who have to have their knee joint changed because the prosthesis has come loose or become worn", she says.
Therefore it is essential that the healthcare service does its utmost to avoid infection in the wound. This means having good ventilation in the operating theatre, securing that the doors are tightly closed, and ensuring that preventive antibiotics are given at exactly the right time before the operation.
"It is also important to be observant of wound complications. If an infection is discovered in time, it is possible to open the wound and clean out the bacteria before they have had chance to spread. Newly operated patients should have a 'VIP lane' so that they can go straight to the hospital orthopaedics department and not have to go via primary care", says Anna Stefánsdóttir.
In Ms Stefánsdóttir's view, re-operations due to infection should be centralised to specialist units, because they require such close cooperation between orthopaedists and infectious disease specialists.
Nowadays, there are orthopaedics clinics that only carry out one such operation a year, which makes it more difficult to establish the best routines.
Photo: U.S. Army
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