Obese patients who undergo weight-loss surgery prior to having a knee or hip replacement may have better outcomes than those who do not undergo weight-loss surgery before such procedures. This is according to the findings of two new studies recently presented at the 2015 Annual Meeting of the American Academy of Orthopaedic Surgeons in Las Vegas.

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Obese patients may have better joint replacement outcomes if they have weight-loss surgery beforehand.

Past research has documented the benefits of weight-loss surgery, or bariatric surgery, for patients who are severely overweight. In November 2014, for example, Medical News Today reported on a study claiming weight-loss surgery is highly effective for preventing type 2 diabetes.

Other studies have found weight-loss surgery may also reduce the risk of heart disease and even some types of cancer for patients who are obese.

But according to lead investigator Dr. Emily Dodwell, an orthopedic surgeon at the Hospital for Special Surgery (HSS) in New York, NY, and colleagues, how weight-loss surgery affects patient outcomes for joint replacements was unclear.

“We know that bariatric surgery is a cost-effective intervention for morbid obesity,” notes study co-author Dr. Alexander McLawhorn, a chief orthopedic surgery resident at HSS. “Yet, the cost-effectiveness of bariatric surgery to achieve weight loss prior to joint replacement and thus decrease the associated complications and costs in morbidly obese patients was unknown.”

With a view to finding out, Dr. Dodwell and her team recruited a number of obese patients who required either a hip or knee replacement. Some patients had a body mass index (BMI) of 40 or higher, while others had a BMI of at least 35 and a minimum of one obesity-related health condition.

The patients were divided into two groups. One group underwent a hip or knee replacement without having weight-loss surgery beforehand, while the other group had weight-loss surgery and underwent a hip or knee replacement around 2 years later.

For the purpose of this study, the researchers assumed that around a third of patients who received weight-loss surgery lost their excess weight prior to having a joint replacement, as patients normally lose weight after the procedure.

“For the study, we chose a decision analysis design because we could use a mathematical model to simulate the outcomes and costs of each treatment path based on results and costs that have already been published in the literature,” explains Dr. Dodwell.

She says their findings indicate that weight-loss surgery for obese patients prior to a joint replacement is “likely a cost-effective option from a public payer standpoint in order to improve outcomes in obese patients who are candidates for joint replacement.”

Dr. Dodwell adds:

Some health care systems do not include weight-loss surgery as a covered benefit, and it is possible that studies such as this will be helpful in re-evaluating whether weight-loss surgery may be a reasonable covered benefit.”

Dr. McLawhorn points out that it would be “impractical” for obese patients with severe knee or hip pain to delay a joint replacement in order to have weight-loss surgery beforehand, particularly since patients with arthritic pain often present to an orthopedic surgeon first.

“Ideally,” he says. “a team approach would be used to treat morbidly obese patients with hip and knee arthritis in which various health care professionals are in place to help a patient lose weight, improve his or her health, and optimize nutrition before joint replacement to maximize its benefits.”

MNT recently reported on another study presented at the 2015 Annual Meeting of the American Academy of Orthopaedic Surgeons, in which researchers found men suffer more complications after joint replacements than women.