Prior studies investigating the etiopathogenesis of surgical site infection (SSI) traditionally suggested three main ways for the infection to occur: local contamination occurring during the surgery, hematogenous translocation of bacteria during concomitant bacteraemia, and contamination from adjacent infected tissues by the progression of the infective process. While most of the research on SSI focused on minimizing any source of pathogens at the time of the surgery, emerging evidence shows how acute and chronic SSI can emerge more often from bacteraemia or other tissues in the body, such as the gastrointestinal system, especially when dysbiosis and high permeability are retrieved.

Intercellular tight junctions (TJs) tightly regulate paracellular antigen trafficking. TJs are extremely dynamic structures that operate in several critical functions of the intestinal epithelium under both physiological and pathological circumstances. This paradigm was subverted in 1993 by the discovery of zonula occludens 1 (ZO-1) as the first component of the TJ complex 11 now being comprised of more than 150 proteins, including occludin, claudins, junctional adhesion molecules (JAMs), tricellulin , and angulins . However, despite major progress in our knowledge on the composition and function of the intercellular TJ, the mechanisms by which they are regulated are still incompletely understood. One of the breakthroughs in understanding the role of gut permeability in health and disease has been the discovery of zonulin, and the only physiologic intestinal permeability modulator described so far.

Since then, zonulin has been used as a marker for increased intestinal permeability and associated with soluble CD14 (sCD14) and lipopolysaccharide (LPS), other common markers associated with surgical complication, inflammation, and bacterial translocations.

As such, Zonulin could be a biomarker for mid- and long-term complications after total joint replacement such as infection, loosening, and mechanical complications associated with painful symptomatology.

Inclusion Criteria:

• Patients who underwent primary or aseptic revision total hip and knee arthroplasty.
• Patients who underwent revision total hip and knee arthroplasty for infective reasons
• Patients 18 years of age or older

Exclusion Criteria:

- Patients younger than 18 years old

Patients who are undergoing a primary or aseptic revision total hip or knee replacement and patients who are having a revision hip or knee replacement for infection