Microbiological analysis of cement spacers in two-stage revision arthroplasty for periprosthetic shoulder infection

Two-stage revision arthroplasty using cement spacers is a well-established treatment strategy for periprosthetic shoulder infection (PSI). As antibiotic-loaded cement spacers lose their efficacy to release local antibiotics over time, they can be colonized, resulting in persisting infection. This study aimed to investigate the prevalence of positive cultures in two-stage revision surgery for PSI and evaluate whether a longer period of spacer implantation is a risk factor for persistence of infection. Patients scheduled for two-stage revision surgery for PSI were enrolled in this prospective cohort study. Periprosthetic tissues samples were colected for microbiological and histopathologic analysis. Sonication analysis of the retrieved implants and spacers was performed at the first- and second-stage sugery, as well as multiplex PCR analysis of the sonication fluid of the cement spacers. Between December 2017 and December 2019, 16 patients (n = 11 female, n = 5 male; mean age 68.1 ± 7.4 years) were included. Mean interval between primary arthroplasty and revision surgery was 41 ± 21 months. PSI was identified in 12 patients (75%). Coagulase-negative staphylococci were the most common isolated pathogens in 11 patients, followed by Cutibacterium acnes in 5 patients. The mean interval between first-and second-stage surgery was 50 ± 21 (range 6–77) days. In 5 patients a more than two-stage procedure was necessary. Microbiological analysis of sonication fluid derived from the retrieved cement spacers was positive in 4 cases (33%) among infected patients, which was independent of the duration of spacer implantation. Microorganisms can be found on cement spacers in two- or more-stage revision surgeries for PSI. The interval between revision surgeries in patients with a positive microbiological result of the retrieved cement spacer was comparable to patients with a sterile cement spacer.