Knee replacement surgery (also known as knee arthroplasty), where the joint is literally removed and replaced with an artificial one, was once thought of as an older person’s surgery or for those with sporting injuries. But the trend towards people under the age of 65 being referred is on the up, and new research has now pinpointed rising levels of obesity as the culprit.
The study, carried out by The University of Massachusetts Medical School, looked at 9,000 knee replacement patients and found that 55% of patients in the under 65 age group were obese, compared with 43% in the group who were 65 or older. And of the patients in the under 65 years age group, 11% were classified as severely (morbidly) obese, compared to 5% in the older age group.
These findings strongly suggest the link between excess weight and the need for knee replacement surgery. The study also found that the younger age group experienced just as much pain and impaired movement prior to surgery as their older counterparts, dismissing the theory that the trend towards surgery at a younger age was simply reflecting patients putting themselves forward earlier to preserve an active lifestyle.
Being overweight puts greater strain on the joints and is a known risk factor for the development and progression of osteoarthritis. Even being just a little overweight puts extra forces and pressure on the knee joint, which may result in premature damage and ultimately lead to the need for knee replacement surgery.
As a nation our waistlines are expanding. Now over 60% of adults in England are classified as overweight or obese. And predictions, published in the Lancet in 2011, have suggested that over half of all men in the UK will be obese by 2030. In the United States, where the research was carried out, about 600,000 knee replacement surgeries are performed each year at a cost of $9.9 billion, with over 40% of those being performed in patients in the younger age category. The total number of knee replacement surgeries is predicted to grow to 3.48 million procedures a year by 2030.
Arthritis Research UK estimates that nearly 20% of people over the age of 45 years now seek treatment for osteoarthritis in the knee and the NHS currently carries out over 70,000 knee replacement surgeries in England and Wales each year. As obesity rates continue to swell this can only lead to an escalation in the need for knee replacement surgery at an increasingly younger age and, with a lifespan of around 20 years for a replacement knee, the spectre of needing additional surgery.