Do Obese Patients Need to Lose Weight Before Total Joint Arthroplasty?
Obesity may not be a barrier to total joint arthroplasty: In a study from the University of Massachusetts Medical School, obese patients who underwent knee or hip replacement surgery reported virtually the same pain relief and improved function as normal weight joint replacement patients 6 months after surgery.
“Our data show it’s not necessary to ask patients to lose weight prior to surgery,” said Wenjun Li, PhD, associate professor of medicine and lead author on the study.
“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.”
The aim of the study, published by the Journal of Bone and Joint Surgery, was to evaluate the extent of pain relief and functional improvement in total joint arthroplasty patients with various levels of obesity. The researchers concluded that although obesity is associated with a greater risk of early complications, obesity itself should not be a deterrent to undergoing total joint arthroplasty to relieve symptoms.
Prior research has documented that obesity is associated with a small, but increased likelihood of infection after total knee arthroplasty, which may discourage obese patients from having surgery.
“However, in this paper we report that obese patients have comparable pain relief and functional outcomes after surgery,” said Patricia Franklin, MD, MBA, MPH, professor of orthopaedics and physical rehabilitation at the University of Massachusetts Medical School.
“Patients should know that these benefits may outweigh risks.”
The researchers collected preoperative and 6-month postoperative data on function, joint pain, and body mass index (BMI) from a national sample of 2040 patients who had undergone total hip arthroplasty and 2964 who had undergone total knee arthroplasty between May 2011 and March 2013.
Preoperative and postoperative function and pain were evaluated according to BMI status, defined as under or of normal weight, overweight, obese, severely obese, or morbidly obese. A greater obesity level was associated with worse pain at baseline but greater postoperative pain relief, with average postoperative pain scores at 6 months similar across the BMI levels.
“This surprised us a little bit. Past analysis showed that obesity is 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,” Dr. Li said.
“Patients who can lose weight should, but we acknowledge many people can’t, or it will take a long time during which their joints will worsen. If they can get the surgery earlier, once function is restored they can better address obesity.”
Co-investigator David Ayers, MD, said that, “Losing weight by making appropriate dietary changes and increasing the calories burned each day through water exercise programs and other aerobic, non-weight bearing activities is always appropriate to decrease the risk of complications for overweight patients.”
Dr. Ayers, the Arthur M. Pappas, MD, chair in orthopaedics and chair and professor of orthopaedics and physical rehabilitation at the University of Massachusetts Medical School, noted that, “This manuscript adds to our collective knowledge regarding the risk benefit ratio of total joint replacement surgery in obese patients.
“The debate will continue in the morbidly obese patients with BMI over 40, and the super obese with a BMI over 50, regarding what steps can and should be taken to lower the risks before these elective surgical procedures.”
Li W, Ayers DC, Lewis CG, Bowen TR, Allison JJ, Franklin PD. Functional gain and pain relief after total joint replacement according to obesity status. J Bone Joint Surg Am. 2017 Jul 19;99(14):1183-1189. doi: 10.2106/JBJS.16.00960.