Does Diabetes Raise Knee Replacement Risks?
Research is mixed on how diabetes affects surgery results.
When arthritis makes it too painful to walk or climb stairs, a knee replacement could be the solution to help you get around more comfortably again. Yet this surgery, like any other procedure, comes with risks that may be even more pronounced if you have diabetes.
The issue is an important one, considering that about half of people with diabetes also have arthritis, and many may eventually need a new knee or two.
Possible Diabetes-related Surgery Complications:
Two studies published in the Bone and Joint Journal in 2014 and 2009 — from Sichuan University in China and Duke University in North Carolina have suggested that people with diabetes face a significantly higher risk of postsurgical complications such as wound infection, stroke, deep vein thrombosis (blood clot), fracture around the implant, and joint loosening, particularly when their diabetes isn’t well controlled.
High blood sugar, the hallmark of diabetes, is thought to cause surgical complications through its adverse effects on many organs and processes in the body.
However, a 2013 study published in The Journal of Bone & Joint Surgery failed to find any association between diabetes and negative surgical outcomes. In that study, researchers retrospectively reviewed the electronic health records of more than 40,000 Kaiser Permanente patients who had a knee replacement.
The investigators looked at three main surgical outcomes: deep infection, blood clots in the legs or lungs, and revision surgery (an operation to replace a failed knee implant). They compared outcomes in people with controlled and uncontrolled diabetes. After adjusting for age, sex, weight and other health problems, the researchers saw no differences in outcomes in patients with controlled or uncontrolled diabetes compared with those who did not have diabetes.
“We were surprised at the findings,” says lead author Annette L. Adams, PhD, research scientist at the Kaiser Permanente Southern California Department of Research and Evaluation in Pasadena. “At first we wondered if we’d made a mistake, because our results were so different from what other people found. It is counterintuitive.”
Yet there are a few caveats. Patients with diabetes in the Kaiser study were generally healthier, tended to have well-controlled diabetes, and had better outcomes overall. The rarity of negative outcomes and uncontrolled diabetes in the study made it harder for the researchers to draw statistically significant conclusions.
Osama Hamdy, MD, PhD, medical director of the Obesity Clinical Program, clinical investigator at the Joslin Diabetes Center in Boston, and assistant professor of medicine at Harvard Medical School, advises interpreting the results with caution.
“Although the [Kaiser] study suggests that you don’t have to postpone elective surgery for total knee replacement if diabetes is uncontrolled, it’s important to remember that this is a retrospective study that is missing [some] very crucial information, such as the type of diabetes treatment, duration of diabetes, and the status of diabetes control during hospitalization when [insulin therapy] can rapidly improve blood glucose levels,” he says.
Does Controlling Diabetes Lead to Better Outcomes?
The Kaiser study didn’t find any difference in outcomes between people with uncontrolled and controlled diabetes. The authors based diabetes control on hemoglobin A1c levels (commonly known as HbA1c or A1c) – a measure of average blood sugar levels during the previous three months. They considered an A1c level of 7 percent or higher uncontrolled diabetes, and a level of less than 7 percent controlled diabetes.
Two studies from Korea did correlate blood sugar control with knee replacement surgery outcomes. Those reports, published in Clinical Orthopaedics and Related Research. 2015 and Clinics in Orthopedic Surgery in 2013 found that people with an A1c level of 8 or higher were more likely to develop wound infections than those with lower numbers.
Before You Have Surgery
Although further research is needed to confirm exactly how diabetes and its control might affect knee replacement surgery results, Adams says diabetes should still be an important consideration as people plan for their procedure. “Doctors and patients need to be mindful of the presence of diabetes when considering major surgery.”