Factors predictive of Cutibacterium periprosthetic shoulder infections: a retrospective study of 342 prosthetic revisions.

BACKGROUND: Cutibacterium are the most common cause of periprosthetic shoulder infections, as defined by ≥2 deep cultures. Established Cutibacterium periprosthetic infections cannot be resolved without prosthesis removal. However, the decision for implant removal must be made from an assessment of infection risk before the results of intraoperative cultures are finalized. We hypothesized that the risk for a Cutibacterium infection is associated with characteristics that are available at the time of revision arthroplasty. METHODS: In a retrospective review of 342 patients having prosthetic revisions between 2006 and 2018 for whom definitive deep culture results were available, we used univariate and multivariate analyses to compare the preoperative and intraoperative characteristics of 101 revisions with Cutibacterium periprosthetic infections to the characteristics of 241 concurrent revisions not meeting the definition of infection. RESULTS: Patients with definite Cutibacterium periprosthetic infections were younger (59 ± 10 vs. 64 ± 12, P < .001), were more likely to be male (91% vs. 44%, P < .001), were more likely to have had their index procedure performed for primary osteoarthritis (54% vs. 39%, P = .007), were more likely to be taking testosterone supplements (8% vs. 2%, P = .02), had lower American Society of Anesthesiologists scores (1.9 ± 0.7 vs. 2.3 ± 0.7, P < .001), and had lower body mass indices (29 ± 5 vs. 31 ± 7, P = .005). Patients with definite Cutibacterium periprosthetic infections also had significantly higher preoperative loads of Cutibacterium on their unprepared skin surface (1.7 ± 0.9 vs. 0.4 ± 0.8, P < .001) and were more likely to have the surgical finding of synovitis (41% vs. 16%, P < .001). CONCLUSIONS: The risk of definite Cutibacterium periprosthetic infections is associated with observations that can be made before or at the time of revision arthroplasty.