06:49pm Thursday 09 July 2020

Malnourished Patients are More Likely to Suffer Postoperative Complications than Morbidly Obese Patients Following Knee, Hip Replacement, Penn Study Finds

LAS VEGAS — Malnourished patients are more likely to have complications following total knee or hip replacement surgeries than morbidly obese patients,according to new research from researchers at the Perelman School of Medicine at the University of Pennsylvania. The findings are being presented at the American Academy of Orthopaedic Surgeons Annual Meeting in Las Vegas March 24-28. 

The Penn team examined 670 patients undergoing total knee or hip replacement. Twelve percent of the patients studied were malnourished, while nearly 19 percent were morbidly obese. Of the total patient population, 10 percent experienced a complication. The investigators found that when compared to patients with normal nutritional status, malnourished patients were nearly 20 percent more likely to have a postoperative complication, 13 percent more likely to be readmitted within 90 days of discharge, 12 percent more likely to have an ICU admission following surgery, and five percent more likely to require a return to the operating room.

“These findings can lead to the development of clear guidelines to identify which patients need remediation before undergoing total knee or hip replacement,” said lead investigator P. Maxwell Courtney, MD, a fourth-year orthopaedic surgery resident at the Perelman School of Medicine at the University of Pennsylvania. “While it would be beneficial for morbidly obese patients to lose weight for better overall health, our findings indicate that doing so is not necessarily indicative of a post-op complication.”

For the purposes of the study, malnourished patients were defined as having a pre-operative serum albumin level, a marker for adequate nutrition, of < 3.5 mg/dL. Morbidly obese patients were characterized by a pre-operative body mass index greater than 40 mg/kg2. Malnourishment so defined is independent of body weight. In fact, because of the greater volume of “empty calories” consumed, morbidly obese patients were more likely to be malnourished than non-morbidly-obese patients.

Among patients with normal nutritional status, morbidly obese patients had no statistically significant difference in complication rates than non-morbidly-obese patients. Malnourished morbidly obese patients also had no statistically significant difference in complication rates than malnourished non-morbidly-obese patients.

“Although our study did not examine whether correcting malnutrition prior to surgery would improve outcomes, it seems prudent to work with dieticians to improve the nutritional levels of patients who are malnourished, whether in the form of better food selection, nutritional supplements, or both,” said the study’s senior author Charles L. Nelson, MD, chief of the Joint Replacement Service in the department of Orthopaedic Surgery, noting that further research on such patients is warranted.

Other Penn co-authors are Joshua C. Rozell, MD, Christopher M. Melnic, MD, and Neil P. Sheth MD.


Penn Medicine is one of the world’s leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation’s first medical school) and the University of Pennsylvania Health System, which together form a $4.9 billion enterprise.

The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 17 years, according to U.S. News & World Report‘s survey of research-oriented medical schools. The School is consistently among the nation’s top recipients of funding from the National Institutes of Health, with $409 million awarded in the 2014 fiscal year.

The University of Pennsylvania Health System’s patient care facilities include: The Hospital of the University of Pennsylvania — recognized as one of the nation’s top “Honor Roll” hospitals by U.S. News & World Report; Penn Presbyterian Medical Center; Chester County Hospital; Penn Wissahickon Hospice; and Pennsylvania Hospital — the nation’s first hospital, founded in 1751. Additional affiliated inpatient care facilities and services throughout the Philadelphia region include Chestnut Hill Hospital and Good Shepherd Penn Partners, a partnership between Good Shepherd Rehabilitation Network and Penn Medicine.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2014, Penn Medicine provided $771 million to benefit our community.

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