Can weight prevent you from having a knee replacement? And if so, what’s the weight limit? Alex Dodds, knee consultant for Cheltenham, Gloucester and the Cotswolds, explains.
*photo courtesy of Margarita Ksenokratova via shutterstock
I watched the comedian Dara O’Briain discussing his knee surgery recently. He joked about the way consultants find increasingly elaborate ways to discuss the issue of weight without ever talking about ‘weight’. His surgeon, apparently, used the phrase: “Well, for a man of your silhouette…”
I think every surgeon will identify with this. It’s never easy to talk to patients about weight, and yet talk about it we must, because the fact is increased weight will make you more likely to need a joint replacement. This is just simple common sense. The heavier you are, the more load your knees need to support. Inevitably, the more you overload your knees, the faster you’ll wear the joint.
But there’s another issue affected by weight. The higher your BMI (body mass index – a measure which, although flawed, is a better gauge than mere weight alone), the more the risks associated with surgery increase.
So decreasing your weight makes sense because it lowers the load on your joints and reduces the risks associated with surgery.
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Is there a weight limit for knee surgery?
Most health providers set a BMI threshold for knee surgery, although private organisations and clinical commissioning groups (CCGs) around the UK set slightly different thresholds. In Evesham, where I run an NHS clinic, for example, the cutoff is 35. In some areas of the country that drops to 30. At the Cheltenham private hospital where I perform knee replacements and other surgeries, the cutoff is 40.
It may feel somewhat arbitrary, but the BMI limits are all about managing risk. The NHS notes that a healthy BMI is between 18.5 and 24.9. Between 25 and 30 surgical risk increases. Above 30, that risk increases still further. There’s a point at which the benefits of, for example, knee replacement are outweighed by the clinical risk of carrying out the procedure.
Chicken and egg
All of which presents a challenge for patients with higher BMIs. How, they may ask, can they lower their BMI when their osteoarthritis prevents them from exercising?
In truth, it’s rare I see patients at my Gloucestershire knee clinic with BMIs above 40, and therefore we should be able to perform surgery, if required, in most cases. Where a patient’s BMI is above 40 and their osteoarthritis is preventing them from taking steps to lower it, I advise them to do what one of my old bosses in London suggested: to enable you to have the operation you want (the knee replacement) first, you should think about another operation (a gastric band or similar). It’s a drastic step, but it can have a dramatic effect on your weight.
That could unlock the knee replacement you want. It could also have many other positive effects on your general health.
Weight and your knee replacement
In summary then, if your BMI is 25 or above and you’re thinking of knee surgery, anything you can do to lower your BMI would be beneficial. As long as your BMI is below 40, though, and assuming there are no other relevant medical issues, being overweight shouldn’t prevent you from having the surgery.
To explore options for your knee surgery, book your appointment at my Cheltenham hip and knee clinic now. Or call 01242 246549.
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