Obese Benefit Equally From Joint Replacement

There is good news for obese patients who are contemplating a joint replacement.

Contrary to previous research, a new study suggests that the obese may not need to lose weight prior to their surgery. The study found that obese patients experience the same pain relief and improved function six months post-surgery as do normal weight patients.

“Our data shows it’s not necessary to ask patients to lose weight prior to surgery,” said Wenjun Li, Ph.D., associate professor of medicine and lead author on of the study, published in the Journal of Bone and Joint Surgery.

He added, “It’s challenging for a patient who is severely overweight and suffering in pain to exercise—often they just can’t do it. Our evidence showed that severe morbidly obese patients can benefit almost equally as normal weight patients in pain relief and gains in physical function.”

For their study the researchers collected preoperative and six-month postoperative data on the function, joint pain and body mass index (BMI) of a sample of 2,040 patients who had undergone total hip replacement and 2,964 who had undergone total knee replacement. The surgeries took place from May 2011 to March 2013. They found that a greater obesity level was associated with worse pain at baseline but greater postoperative pain relief. The average postoperative pain scores at six months were similar across the various BMI levels.

This outcome surprised the researchers, Li said. “Past analysis had shown that obesity was associated with outcomes to some degree. But here we see the magnitude is so small it won’t make much difference, and severely obese patients can benefit a lot from the surgery.”

Patricia Franklin, M.D., MBA, MPH, professor of orthopedics and physical rehabilitation, said, “Patients should know that these benefits may outweigh risks.”