Materials
Stages of osteoarthritis. Although the early stages of osteoarthritis involve much less cartilage loss than later stages, there’s no correlation between how advanced the disease is and how much pain is experienced.
Stage I: Doubtful
Minimum disruption. There is already 10% cartilage loss.
Stage II: Mild
Joint-space narrowing. The cartilage begins breaking down.
Occurrence of osteophytes.
cartilage then leading to bone-on-bone contact. “There are different grades of osteoarthritis, which are graded by X-ray appearance, but there is unfortunately no correlation between the grade of the disease and the pain,” explains Richie Gill, professor of mechanical engineering at the University of Bath. “Some people with very worn cartilage may experience less pain than those in the early stages of the disease,” he says. Typically, knee osteoarthritis can be treated successfully with a knee replacement surgical procedure, which involves removing the natural joint structures and replacing them with metal and plastic. Obviously, however, such a procedure is going to be irreversible. Furthermore, the operation is only performed at the end stage of the disease because over time (usually about 10–15 years), the replacement can fail, and revision surgery – more complicated than the original replacement surgery – will need to be carried out. For that reason, Gill says, surgeons rarely offer knee replacement operations to people under the age of about 60 or 65.
“There are different grades of osteoarthritis, which are graded by X-ray appearance, but there is unfortunately no correlation between the grade of the disease and the pain.”
Approximately 15% of knee replacement patients are dissatisfied with their surgery, and younger patients report greater levels of dissatisfaction, as well as a greater incidence of revision. Yet, as the population continues to age, data suggests that
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Stage III: Moderate
Moderate joint-space reduction. Gaps in the cartilage can expand until they reach the bone.
Stage IV: Severe
Joint-space greatly reduced. 60% of the cartilage is already lost.
Large osteophytes
demand for the operation will double by 2030, Gill says.
Backlog of patients awaiting surgery Because patients must wait till a very late stage of the disease for a knee replacement, some experience intense pain for decades before they are able to have a replacement – and thanks to the pandemic, there is currently a backlog of patients waiting for the operation. Some doctors continue to prescribe opioids to manage the pain, despite the evidence that they don’t work and can even create further problems. The only way to treat osteoarthritis in the knee effectively, Gill points out, is to correct the mechanics. One of the problems with waiting so long to perform knee surgery – apart from the pain caused to the individual patient – is that the condition renders people inactive. And, as Gill points out: “If you are inactive, you have multiple risk factors for other things [like] diabetes [and] cardiac disease, for example.”
So, there are good reasons to treat knee osteoarthritis at an earlier stage, if possible. The main alternative treatment to knee replacement is a surgical technique known as high tibial osteotomy. This involves cutting a wedge of bone out of the top of the tibia to realign the knee, which is then stabilised by screwing a metal plate into the bone on the outside of the joint. The load on the inside of the knee is reduced, and the healthier part of the knee bears more of the weight. If successful, the bone can regrow and the reduced load on the knee can allow the damaged cartilage to regenerate. The plate can then be removed after about a year.
Medical Device Developments /
www.nsmedicaldevices.com
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