It´s all about explained variation in the periprosthetic joint infections

I showed this slide in my clinic meeting presentation which was about periprosthetic joint infections. Infection rates were very high in the early years of modern total joint replacement surgery in 1960s. Today, the risk of deep infection after a total hip or knee replacement surgery is something close to 1%. This major improvement is mainly due to aseptic techniques, antibiotic prophylaxis and disinfection and sterilization in general. I would propose that 95% of the improvement in infection rates are due to these factors (Proportion of each entity is completely arbitrary).

Massive efforts are still made to reduce this already low infection rate even more. At this point it is relevant to ask whether this is wise or feasible. It is impossible to have 0% infection rate. In the slide I have listed factors which have been anecdotally associated with an increased or decreased risk of an infection. Naturally there are other factors also at play, especially patient-related factors. But the factors listed below are those which could be in theory optimized and controlled in a standardized way in the clinical practice.

But what is the amount of explained variation of each factor listed in the figure? It is reasonable to assume that each one of them may have some role in the development of a deep infection. I postulate that the contribution of each separate factor is so small that it is almost impossible to investigate each effect separately, ie. in randomized controlled trial. So, how much we can improve our infection rates from the level we have reached in 2020? How much research we still need on this topic?

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