TKA Infections: Winter Months Safer Than Summer?

Does the revision rate for total knee arthroplasty (TKA) because of post-op prosthetic joint infections vary between tropical and non-tropical areas…or seasons? Are the winter months safer than summer?

These questions and more were addressed in the study, “Is Climate Associated With Revision for Prosthetic Joint Infection After Primary TKA?” The article was published in the June 2018 edition of Clinical Orthopaedics and Related Research.

Co-author Ben Parkinson, FRACS (Orth) of the Department of Orthopaedics, Cairns Hospital, Cairns, Queensland, Australia told OTW, “I practice in a tropical region of Australia and we have been observing a very clear seasonal variation in the incidence of osteomyelitis and myositis over many, many years.”

“I wondered if our arthroplasty population was also at an increased risk of infection during the warmer monsoonal season.”

“Existing literature does show a seasonal variation for many types of infections, but no prior studies looked specifically at the seasonal variation in knee arthroplasty patients, so we decided to conduct this study to investigate this further.”

All 219,983 primary TKAs performed for osteoarthritis over a 5-year period (2011-2015) in the Australian Orthopaedic Association National Joint Replacement Registry were examined based on the month of the primary procedure to determine the rate of revision for PJI within 12 months…”

Dr. Parkinson told OTW, “The important finding of our study was that there is a seasonal variation of TKR [total knee replacement] infection rates within tropical regions.”

“This variation was not however evident within the more temperate regions of Australia. We can only postulate to why, but our suspicion is that it is the high humidity during the summer periods of tropical Australia that is exerting the effect on patient’s infection risk. We are currently working on other studies to follow these findings to try and determine how the climatic factors exert this effect.”

“The results of this study apply to surgeons who practice in sub-tropical and tropical regions.”

“They should not be alarmed by our study results, as the effect size of these findings mean 1 extra prosthetic joint infection per 200 cases performed in summer. This risk is still not insignificant but there are many other PJI risk factors such as diabetes, smoking and obesity that exert a greater risk for PJI [periprosthetic joint infection].”

“If surgeons have optimized their patients and are concerned about the climatic influence, they could look to schedule their arthroplasty procedures for the winter months.”

“Hopefully this study prompts surgeons to take a moment to think about PJI risk factors in general, as there are so many different factors that influence a patient’s risk for PJI. This study is just another small piece of the overall puzzle.”