contaminazione del campo operatorio in protesi totale elettiva di spalla

Introduction: Reverse total shoulder arthroplasty (RTSA) has become a widely accepted surgical treatment for various complex shoulder conditions, including rotator cuff tear arthropathy (RCTA), massive irreparable cuff tears (MIRCTs), primary osteoarthritis, fractures in the elderly, and failed previous shoulder replacements. RTSA has shown excellent clinical outcomes in alleviating pain and restoring shoulder function in challenging cases where traditional anatomic shoulder replacements are less effective. As the number of patients undergoing RTSA continues to rise, so too does the incidence of complications associated with this procedure. The most common complications include periprosthetic infection, dislocation of the prosthesis, periprosthetic fracture, and neurological injuries. Periprosthetic joint infection (PJI), can be a severe complication following shoulder arthroplasty with the potential for significant consequences. Cutibacterium acnes (C. acnes), formerly known as Propionibacterium acnes, and coagulase-negative staphylococci (CoNS) are prevalent pathogens in shoulder joint infections, often leading to low-grade postoperative infections. The shoulder region's high C. acnes prevalence poses a heightened infection risk compared to hip or knee surgeries, as this bacterium, residing in hair follicles and sebaceous glands, is challenging to completely eradicate despite rigorous skin preparation efforts. Several studies have consistently identified male gender as a notable risk factor for developing PJI following shoulder arthroplasty. In particular, men are 1.5 to 3.5 times more likely to experience this complication compared to women. In addition to gender, younger patient age has also been associated with a higher risk of shoulder PJI. The reasons for this association are not entirely clear but may relate to factors such as activity level or comorbidities. The risk of surgical site infection (SSI) is minimized through prevention methods, such Even though all these precautions are taken before surgery contamination by C. acnes is still present. Methods: In this study 55 patients – 35 (63,6%) female and 20 (36,4%) male - were enrolled for primary reverse total shoulder arthroplasty. After the procedure 3 samples were taken two from the prosthetic components and one from the periprosthetic tissue. These samples were then seeded on various media suitable for the growth of aerobic and anaerobic bacteria and fungi. After incubation, the dominant microorganisms were analysed using bacteriological methods and identified by MALDI-TOF mass spectrometry. Results: The most prevalent pathogenic bacterium isolated and identified under anaerobic conditions was C. acnes. Specifically, 29 out of 55 patients (52,72%) tested positive for C. acnes, with the bacterium detected in 27 swabs from prosthetic components and 22 periprosthetic tissues. In aerobic conditions CoNS group was the most respresented, The positivity of cultures in the case of C. acnes turned out to be related to the gender, age, some comorbidities, the duration of the surgery and to a certain point to the diagnosis. For what concerns CoNS instead results were not statistically significant. These results allow us to affirm that surgical field contamination is present in RTSA and that the most common contaminant is C. acnes. The presence of the latter in cultures is related mainly to gender and to a certain extend to age, comorbidities, duration of the surgery and diagnosis.