Bariatric surgery impacts joint replacement outcomes in very obese patients

March 14, 2017

A study from Hospital for Special Surgery (HSS) finds that in morbidly obese patients, bariatric surgery performed prior to a total hip or knee replacement can reduce in-hospital and 90-day postoperative complications and improve patient health, but it does not reduce the risk of needing a revision surgery.

The study was presented at the American Academy of Orthopedic Surgeons Annual Meeting on March 14 in San Diego.

"With our data, I think we can say with confidence that bariatric surgery prior to total joint replacement is not a harmful recommendation," said lead study author Alexander McLawhorn, MD, MBA, an assistant attending orthopedic surgeon at Hospital for Special Surgery in New York City. "As an orthopedic surgeon, you are not going to compromise your joint replacement outcome if you advise a morbidly obese patient to seek an opinion from a bariatric surgeon."

Morbid obesity (a body mass index greater than or equal to 40 kg/m2) is associated with poor postoperative outcomes after total knee arthroplasty (TKA) and total hip arthroplasty (THA), including increased risk for revision surgery, postoperative infection, and medical complications. Previous studies have shown that bariatric surgery in patients who are morbidly obese can reduce weight and comorbidities, but clinicians have not known whether the surgery is helpful or harmful to morbidly obese patients undergoing a joint replacement.

Because bariatric surgery has a major impact on the metabolic system, creating a malnourished state, some clinicians have worried that the surgery might have a negative impact on total joint replacement. Others have believed it might improve outcomes by reducing weight and thus the load on a hip or knee joint.

To shed light on the issue, researchers at Hospital for Special Surgery turned to the New York Statewide Planning and Research Cooperative System (SPARCS) database, a comprehensive all payer data reporting system. They identified all morbidly obese patients who had a THA or TKA in New York State between 1997 and 2011. There were 2,636 patients who underwent a total knee replacement and 792 who underwent a total hip replacement after bariatric surgery.

The researchers then used propensity score matching to build control groups of morbidly obese patients receiving total hips and knees without prior or subsequent bariatric surgery. Propensity score matching is a statistical technique that attempts to estimate the effect of a treatment by accounting for the covariates that predict receiving treatment. The propensity score was defined as the conditional probability of a patient undergoing bariatric surgery, given his or her baseline characteristics, including: age, year in which a total hip or total knee replacement was performed, laterality (unilateral versus bilateral surgery), sex, health care payer, region (rural versus urban), and Elixhauser comorbidities.

Statistical analyses showed that bariatric surgery lowered the comorbidity burden of patients prior to total joint replacement (P<0.0001 for TKA and P<0.005 for THA). Morbidly obese patients who had bariatric surgery had lower rates of in-hospital complications for total hip replacement (1.5% vs. 5.3%; P<0.0001) and for total knee replacement (2.7% vs. 3.9%; P=0.021). Put another way, morbidly obese patients who had bariatric surgery were 75% less likely to have in-hospital complications from a total hip replacement and 31% less likely to have in-hospital complications for a total knee replacement. The risk for 90-day postoperative complications was also lower in patients who received bariatric surgery, 14% lower in the THA group (odds ratio [OR], 0.86; P=0.041) and 61% lower in the TKA group (OR, 39%; P=0.0019). Bariatric surgery did not lower the risk of having a revision surgery or the risk for a hip dislocation.

Other healthcare claims database studies have been conducted looking at joint replacement in morbidly obese patients, but results have been inconsistent, most likely due to selection bias. "When you look at the design of the other studies, the single biggest flaw is they don't try to account for the very real selection bias that exists for morbidly obese patients who received bariatric surgery versus those that do not," said Dr. McLawhorn. "The patient population that is indicated for bariatric surgery is different than the universe of patients who are just morbidly obese. They tend to have a much higher comorbidity burden, and they tend to be sicker and heavier. We accounted for this selection bias in our study."

The researchers say a prospective trial examining the impact of bariatric surgery on a TKA in morbidly obese patients is in the works. "Orthopedic surgeons are seeing a lot of these patients who are morbidly obese and have hip and knee arthritis," said Dr. McLawhorn. "The question is how do we optimize these patients who have a real problem with their hip or knee and the comorbid condition of obesity, so that they can achieve maximal benefit from their joint replacement."

In another recent study by HSS researchers, a cost-effectiveness analysis using prior literature and expert opinion, bariatric surgery prior to TKA was deemed cost-effective for improving outcomes in morbidly obese patients with end-stage knee osteoarthritis indicated for a knee replacement (J Bone Joint Surg Am. 2016;98(2):e6).
-end-
About Hospital for Special Surgery

Hospital for Special Surgery (HSS) is the world's largest academic medical center focused on musculoskeletal health. HSS is nationally ranked No. 1 in orthopedics and No. 2 in rheumatology by U.S. News & World Report (2016-2017), and is the first hospital in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center four consecutive times. HSS has one of the lowest infection rates in the country. HSS is an affiliate of Weill Cornell Medical College and as such all Hospital for Special Surgery medical staff are faculty of Weill Cornell. The hospital's research division is internationally recognized as a leader in the investigation of musculoskeletal and autoimmune diseases. Hospital for Special Surgery is located in New York City and online at http://www.hss.edu.

Hospital for Special Surgery

Related Bariatric Surgery Articles from Brightsurf:

Statement on metabolic and bariatric surgery during COVID-19 pandemic
The American Society for Metabolic and Bariatric Surgery (ASMBS), the leading organization of bariatric surgeons and integrated health professionals in the nation, declared metabolic and bariatric surgery 'medically necessary and the best treatment for those with the life-threatening and life-limiting disease of severe obesity' and called for the safe and rapid resumption of procedures, which have been largely postponed along with other surgeries deemed elective amid the COVID-19 pandemic.

Examining association between weight loss before bariatric surgery, risk of death after surgery
Researchers looked at whether a patient's body weight and weight loss before bariatric surgery were associated with risk of death within 30 days after surgery using data from nearly 500,000 patients in the US and Canada.

Bariatric surgery effective against early-onset obesity too
Surgical treatment of obesity is as effective for individuals who developed the disorder early, by the age of 20, as for those who have developed obesity later in life, a study from the University of Gothenburg shows.

Lower risk for malignant melanoma after bariatric surgery
Bariatric surgery is associated with a distinct reduction in skin-cancer risk, a study shows.

Study shows risks for additional procedures after bariatric surgery
Which of the two most common bariatric surgeries -- gastric sleeve or gastric bypass -- has the highest subsequent risk of additional operations or procedures?

Studies continue to highlight benefits of bariatric surgery in teens
Children's Colorado researchers and their colleagues found that musculoskeletal pain, physical function and quality of life in adolescents significantly improves and is maintained three years after bariatric surgery.

Bariatric surgery may not lead to lower health care costs
Despite helping to bring about improved survival and significant weight loss, bariatric surgery may not lead to lower health care costs in the long term, says a Veterans Affairs study.

Bariatric surgery is safe for teens with morbid obesity
Bariatric surgery is safe and, in many cases, beneficial for teenagers with morbid obesity who would otherwise face a heightened risk of developing severe health problems, including heart disease and stroke, according to a new study from Penn Medicine and the Children's Hospital of Philadelphia (CHOP).

Criteria for bariatric surgery should consider more than just patient's weight
More than one-third of Americans are obese, and while more than 250,000 bariatric surgeries are performed annually in the United States, experts at The Ohio State University Wexner Medical Center and 45 worldwide scientific and medical societies say surgery should be an option for many more patients.

Bariatric surgery can be safe and effective for adolescents
Pediatricians are often reluctant to recommend bariatric surgery for teen-agers, but a Rutgers-led study concludes it is a justifiable treatment for adolescents with persistent extreme obesity if they can maintain a healthy lifestyle afterward.

Read More: Bariatric Surgery News and Bariatric Surgery Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.