Dad is a smoker, drinker, and overeater. The surgeon has warned him these are all important factors that could lead to an infection after knee replacement. He still insists he wants a new knee (without doing anything to clean up his act). Should the surgeon really be allowed to give him a knee replacement if he’s going to get an infection? Should we try and stop this?

The three factors you mentioned (smoking, alcohol use, and diet) are important considerations. Malnutrition, urinary tract infection, and a history of diabetes, cancer, and rheumatoid arthritis are risk factors linked with joint infections after knee replacement. Anyone with a blood clotting disorder or taking medications to reduce clot formation (anticoagulants) must be watched carefully as well.

How likely is it that your father would develop an infection after surgery? Studies report the risk of periprosthetic infection is anywhere between 0.4 and two per cent for adults receiving a knee replacement. The upper number includes those patients who are diagnosed with an infection early on (first year after the procedure) as well as infections reported 10 years later.

Periprosthetic infection refers to infection in and/or around the implant and joint in which the implant is located. Most of the infections are caused by staphylococcus aureus more commonly known as a “staph” infection. The distinction between periprosthetic and wound infection is made here by just mentioning periprosthetic infections. Infection around the incision and soft tissues is a separate issue.

The surgeon would not perform a total knee replacement procedure if your father wasn’t a good candidate. But as with all surgeries, patients must be warned of potential risk factors, complications, and problems that can arise. Your concern for your father is important. If possible, go with your father to a pre-op appointment and ask questions to help you gain a better understanding of the perceived versus real concerns and risks.