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Last updated on April 16, 2014 at 17:34 EDT

Obesity Takes Heavy Toll On Knee Arthritis

February 14, 2011

New studies will help patients better understand the role that obesity plays in knee arthritis and recovery from knee surgery

More than 14 million visits were made to physicians’ offices in 2008 by patients with knee problems. Five new studies presented at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS) look at the effect that obesity has on knee arthritis and a patient’s ability to recover from knee surgery.

Does Obesity Cause Irreparable Damage To Knees Despite Weight Loss? (Embargo: February 15)

One new study found that while weight loss via bariatric surgery may improve knee pain in obese patients with knee osteoarthritis, there may be permanent damage to the knee from being morbidly obese.

The investigation included 10 morbidly obese patients with knee osteoarthritis who were evaluated before and after bariatric surgery. Patients lost an average of 51 pounds in one year. One year after surgery, knee pain and function improved significantly.

“For a long time people felt there was nothing they could do to mitigate the debilitating effects of knee arthritis, but now we know that surgically-assisted weight loss is a way that folks can help themselves,” says Michael S. Sridhar, MD, co-investigator and resident at Emory University. “However, there is probably some element of irreparable damage from being morbidly obese that may constrain the improvement in knee pain despite significant weight loss. Looking at the actual joint surfaces with advanced imaging to assess damage is the exciting next step in studying the evolution of knee arthritis in the obese population.”

Are ‘Super-Obese’ Patients At Greater Risk For Post-Surgery Complications? (Embargo: February 15)

Also, two new studies released today examine whether obesity contributes to greater complications after hip and knee replacement surgery. The first study considers patients in the “super obese” category who have a body mass index (BMI) greater than 45. Few studies have examined whether complication rates for total joint replacement (TJR) patients may increase for “super-obese” patients.

This study compared the outcomes after TJR in 137 “super-obese” patients versus 63 non-obese patients.

Ran Schwarzkopf, MD, co-investigator and chief resident, New York University Hospital for Joint Diseases, and his research team found that the number of overall complications were significantly higher for the “super-obese” compared to non-obese. Among “super-obese” patients, each 5-unit increase in BMI over 45 was associated with a statistically significant increased risk of having in-hospital and post-operative outpatient complications or readmission. Also, days to discharge were found to increase by almost 14 percent for each 5-unit increase in BMI over 45.

The second study analyzed complication rates for morbidly obese patients (BMI greater than 40) after TJR. The study reviewed data from 12,355 patients and compared complication rates in morbidly-obese patients versus normal-weight patients.

Led by Richard J. Friedman, MD, FRCSC, co-investigator and Chairman, Department of Orthopaedic Surgery, Roper Hospital, Charleston, SC, the study found that morbid obesity contributed to a significantly higher incidence of complications such as redness around the surgical wound, swelling of the legs, bacterial infections, respiratory disorders, neurologic and gastrointestinal complications and cardiac arrhythmias following total hip and knee replacements. Study abstract. (Embargo: February 18)

Will Isolated Weight Loss Improve Knee Pain and Movement? (Embargo: February 15)

Another new study released today analyzed the effects of isolated weight loss via bariatric surgery on knee osteoarthritis. The study involved 24 obese patients with knee osteoarthritis who were scheduled to undergo bariatric surgery. Patient weights and knee symptoms were recorded before the surgery and 6 and 12 months after surgery. Patients were not prescribed exercise or physical therapy, anti-inflammatory medications or knee injections post-operatively.

The study found that isolated weight loss following bariatric surgery resulted in significant improvements in knee pain, stiffness and function.

“Other studies have looked at the effect that a combination of weight loss, diet and exercise had on knee arthritis, but it was difficult to say which of these factors contributed the most to reducing knee pain,” says Christopher Edwards, co-investigator and a fourth year medical student at the Penn State College of Medicine. “Our study should send a message to patients, health care providers, and payers that weight loss is an important consideration in the treatment of knee arthritis.”

Can We Explain the Dramatic Rise in TKR Rates in the US by Population Size and the Obesity Epidemic? (Embargo: February 17)

Elena Losina, PhD, co-director, Orthopedics and Arthritis Center for Outcomes Research at Brigham and women’s Hospital Associate and Professor of Orthopedic Surgery, Harvard Medical School , led a research team to examine trends in total knee replacement (TKR) utilization and found that it doubled during the decade from 1997-2007. The proportion performed in younger groups tripled. The proportion of obese persons increased by about 15 percent between 1997 and 2007. Such an increase in the obesity epidemic could explain about 20 percent of the increased utilization of TKR. Data suggests that expanding the indications for TKR in younger ages (due to sport-related injuries, obesity and as a consequence, early onset of osteoarthritis) is the likely explanation for the dramatic increase in TKR rates in the US.

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