My colleagues and I are involved in an evidence-based Cochrane Review of the use of antibiotic and antiseptic prophylaxis in hip or knee replacement to prevent infections. These types of infections cost the U.S. health care system more than $1 billion a year in unnecessary treatment. What we have found most interesting in our research is the lack of evidence that antibiotic and antiseptic prophylaxis is even effective.

As a brief history, the use of preoperative antibiotics administered within an hour of surgery has been found to be effective in reducing infection rates during surgery. If antibiotics are administered outside this time window or not administered at all, however, infection rates go up exponentially. This was discovered back in 1992, in an article published in the New England Journal of Medicine. This evidence has been subsequently applied to all types of surgery including primary knee and hip replacements.

Specific to these joint replacements, evidence of efficacy isn’t due to lack of trying. We have identified 27 randomized controlled trials on the use of antibiotic or antiseptic prophylaxis since 1973. However, the issues with these studies are that most of them were performed more than 20 years ago. Since then, patient demographics have changed in a meaningful way—with a higher incidence of obese and diabetic patients undergoing these types of procedures.

The orthopedic community in the United States does not have a good handle on whether the current antibiotic prophylaxis regimens work as they should in these types of patients. Add to this a more active and longer-lived patient population, and the risks for infection increase. As well, antibiotic resistant bacteria are becoming increasingly prevalent with methicillin-resistant staphylococcus aureus (MRSA) and Clostridium difficule (C diff), creating issues in treatment and significant comorbidities, including death.

We need more up-to-date studies examining these issues.

A lack of evidence in antibiotic prophylaxis is not an isolated issue. As has been mentioned in an oft-cited review by the Institute of Medicine, “Knowing What Works in Health Care, A Roadmap for the Nation,” published in 2008, clinicians use a concept called “mindlines” in deciding what to do. Mindlines involve the use of tacit, internal guidelines derived from one own’s experience or the experience of colleagues in deciding what is best for the patient. Unfortunately, this type of medicine is typically not the best way to practice the craft.

Another issue in practicing good medicine is a lack of understanding of rigorous study design and statistics. Better study design might be a very good course for clinicians in a medical school curriculum. It certainly occurs in developed countries outside the U.S.

What we need in the U.S. are up-to-date analyses and training. Until these occur, issues such as infections after knee and hip replacements will continue at a higher rate than the research needed to prevent them.