Studies show that forced-air warming (FAW) reduces soft-tissue surgical infections. How can FAW be linked to increased deep-joint infections?

The paradox is easy to explain: BIOFILM.  A bacterium that lands on a prosthetic implant can secrete a coating of biofilm that protects it from both antibodies and antibiotics. Bacteria in soft-tissue cannot form effective biofilm coatings.

Secretion of biofilm allows a single airborne germ to cause a deep infection of a joint implant (Lidwell, 1983).  When the germ lands on the new implant, it protects itself in a biofilm coating and then sprouts weeks-to-months later as a catastrophic deep joint infection.  The increased airborne contamination from FAW vastly increases the chances of an airborne bacterium landing on the new implant.

In contrast, without biofilm protection, the germs in soft-tissue are susceptible to antibiotics and to an immune system activated by heat.  As a result, the creation of soft-tissue surgical infections require large inoculums of more than 100,000 germs (Elek & Cohen, 1957).

This also explains why soft-tissue surgical infections may not be increased by contaminated FAW air, while blowing even one germ into the surgical site during implant surgery can have significant negative concequences.

Watch this terrific video about bacterial biofilms produced by the Arthroplasty Patient Foundation:

Here is another interesting video about bacterial biofilms and orthopedic implants produced by the Arthroplasty Patient Foundation: