Need Knee Replacement? Bariatric Surgery Might Help

Every year in the U.S., surgeons perform about 800,000 knee replacements. By comparison, fewer than half as many – less than 300,000 – bariatric surgeries occur each year. Especially in younger patients needing knee replacement, obesity is quite common. In one study, 72 percent of knee replacement patients under 60 had obesity. So it’s quite natural to ask if bariatric surgery might help folks who are candidates for knee replacement.

Now, results from an RCT tell us the answer seems to be yes. Michelle Dowsey and colleagues published their findings last week in JAMA Network Open.

Random Assignment to Bariatric Surgery

A total of 82 patients waiting for knee replacement surgery received a random assignment to either bariatric surgery or the usual weight management advice. In the bariatric surgery group, patients underwent a laparoscopic adjustable gastric band procedure.

The difference in outcomes was quite clear. Of course, the bariatric surgery group lost weight. At the outset, both groups had a mean BMI of about 44. After 12 months, BMI in the bariatric surgery group was significantly lower – an average of 37, compared to 43 in the usual advice group.

But the primary outcome for this study was complications from knee replacement surgery. On this dimension, the results were clearly better for the bariatric surgery group. Only 15 percent of the bariatric surgery patients had a complication from knee replacement. More than twice as many – 37 percent – in the usual care group had a complication.

Part of the reason for this difference is that 29 percent of the bariatric surgery patients decided they didn’t need a knee replacement after all. The pain and function of their knee improved after they lost weight. By comparison, only 5 percent of patients in the usual advice group opted out of knee surgery.

Physical Reality

This is a physical reality of obesity. Excess weight causes pain and reduced function in a person’s knees. For someone with moderate or severe obesity, two kinds of surgery can help. Bariatric surgery goes to the root of the problem. Knee replacement fixes the damage that’s already taken place.

It makes a whole lot of sense to treat obesity – sooner rather than later – to prevent further damage to a person’s knees. And if knee replacement surgery is needed, the results are likely to be better if a person has bariatric surgery first.

Click here for the study by Dowsey et al. For further perspective on outcomes from knee replacement in persons with obesity, click here, here, and here.

Sketch of a Knee, painting by Vincent van Gogh / WikiArt

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April 20, 2022