After Karen Miletsky had lap-band surgery in 2014, she dropped from 187 to 132 pounds, achieving a healthy weight for her 5-foot, 2-inch frame. Her energy went up, her fatty liver disease markedly improved, and she finally felt good about shopping for clothes.

But there was another benefit she wasn’t quite expecting: the debilitating arthritic knee pain she had dealt with since her mid-30s began to ease up. “Before the surgery, I wouldn’t even think of walking an extra few blocks,” says Miletsky, 66, who lives in Old Bridge, New Jersey. Now, she strolls regularly and can handle stairs without worrying that her knees might buckle.

Miletsky is one of 120 patients from NYU Langone’s Weight Management Program who participated in a study comparing knee pain before and after laparoscopic adjustable gastric banding, or lap-band, surgery performed between 2002 and 2015.

Considered the least invasive type of bariatric surgery, the 30-minute procedure involves the placement of an inflatable band around the upper stomach to limit food intake and reduce hunger.

The study results, recently published in Seminars in Arthritis and Rheumatism, showed that patients who lost the most weight following the procedure experienced the greatest relief. That makes sense when you consider gravity’s multiplying effect: one extra pound of body weight exerts about four pounds of extra pressure on the knee joint.

The study also showed that younger patients experienced greater pain relief and more knee mobility than older ones, suggesting that having the procedure done earlier in life might slow down or prevent future damage to the knees.

Christine J. Ren-Fielding, MD, division chief of bariatric surgery and one of the study’s authors, says up to 20 percent of NYU Langone’s bariatric patients are referred by orthopedic surgeons hoping to fend off knee replacement. “Often people come to us due to diabetes or poor quality of life or sleep apnea, and then they’ll say, ‘Oh, and my knees hurt, which is why I can’t exercise,’” Dr. Ren-Fielding says.

Surprisingly, the postsurgical relief isn’t just a matter of lightening the load. Rheumatologist Jonathan Samuels, MD, the study’s senior investigator, notes that metabolic changes resulting from weight-loss surgery may also contribute to knee-pain relief. “We and other investigators have seen the levels of certain inflammatory markers, some of which have been shown to affect knee arthritis progression in other studies, drop after weight-loss surgery,” says Dr. Samuels.

Whatever factors are responsible for the improvement, this latest study lends credence to the idea that bariatric surgery can be an effective way for overweight and obese patients to avoid knee replacement. “Having a lap-band procedure is less invasive, requires less recovery time, and risks fewer potential complications,” says Dr. Ren-Fielding. Plus, a knee replacement only lasts for 10 years. “So even delaying it as long as possible may prevent the need for a second knee surgery,” she says.

For Miletsky, it’s one more powerful reason to keep the weight off. “My knee is feeling much better, and my legs feel more stable,” she says. “I’m hopeful I won’t need a knee replacement now.”

The Three Most Common Options for Bariatric Surgery

NYU Langone Health performs 1,000 weight-loss surgeries each year, more than any other medical center in the United States. The techniques below are widely accepted as the safest and most effective, notes Dr. Ren-Fielding.

Sleeve Gastrectomy

The most commonly performed bariatric procedure, this method facilitates rapid weight loss; a typical patient will lose 80 to 100 pounds within the first six months. About 80 percent of the stomach is removed, making patients feel full sooner. Compared with other methods, it allows for the most normal digestive process and nutrient intake.

Gastric Bypass

Morbidly obese patients are prime candidates for this procedure. The digestive tract is rerouted around the stomach and part of the small intestine, limiting food absorption. Gastric bypass often reverses type 2 diabetes, possibly by changing gut hormones, although the reasons are still unclear.

Laparoscopic Adjustable Gastric Banding

Lap-band is ideal for patients who prefer a reversible procedure and need to lose fewer than 50 pounds. An inflatable, adjustable silicone band is placed around the top part of the stomach, limiting food intake.