Strategies Improve TKR Outcomes in Obese Patients

A new study reviews preoperative considerations, intraoperative treatments, and postoperative care needed to improve total knee replacement (TKR) outcomes in the morbidly obese.

Researchers at the University of Tennessee, OrthoCarolina, and other institutions conducted a review of studies to improve the understanding of the medical and surgical complications associated with TKR in the obese patient. They report that preoperative considerations should include awareness of chronic conditions, such as high blood pressure or diabetes, and optimization of nutritional status by testing for nutritional deficiencies, as malnutrition is just as common in people with obesity as in patients who are on low-calorie diets to lose weight.

Patients should then be advised of safe weight loss strategies, including bariatric surgery, with the goal of reducing their body mass index (BMI) prior to surgery, as an excess soft tissue in these patients can obstruct surgeon visibility in the treatment site, resulting in a difficulty to achieving proper alignment and implant fixation, as well as longer surgical times. The researchers also recommend using imaging techniques such as computer-assisted alignment that may expedite surgery and minimize complications.

Post-surgery, patients with obesity are at a higher risk for revisions due to decreased longevity of the implants and tibial loosening. The morbidly obese patient also faces an elevated risk of surgical site infection (SSI), cardiovascular events, and respiratory complications. The researchers added that while prior studies have not evaluated methods for decreasing these post-surgical complications, the data suggests it may be beneficial to utilize implants with improved fixation. The study was published in the March 2017 issue of the Journal of the American Academy of Orthopedic Surgeons.

“Until recently, little was known about the outcomes of patients with obesity undergoing TKR. We sought to review what information is known and what areas need further investigation,” said lead author and orthopedic hip and knee surgeon J. Ryan Martin, MD, of UTK. “Although further research is needed, this review has allowed us to identify a variety of treatment methods to improve outcomes and reduce complications in patients with obesity.”

Obese patients suffer higher rates of postoperative complications than non-obese patients, including a five times higher rate of heart attack, four times higher rate of peripheral nerve injury, 1.7 times higher rate of wound infection, and a 1.5 times higher rate of urinary tract infection (UTI). And while overall mortality does not vary between the obese and non-obese, the death rate is nearly twice as high among morbidly obese patients compared with non-obese patients.