Are high cutibacterium bacterial loads at the time of revision shoulder arthroplasty associated with more severe clinical signs or symptoms or increased risk of recurrent periprosthetic joint infection?

Purpose: Cutibacterium is commonly isolated from deep tissue samples taken at the time of revision shoulder arthroplasty, but the significance of these positive cultures is debated, and the impact of increasing bacterial loads on clinical outcomes is unclear. The objectives of this study were to (1) identify factors independently associated with high bacterial loads, and (2) compare patient-reported outcomes (PROs) and revision rates in patients found to have high Cutibacterium loads.

Materials And Methods: Male patients undergoing single stage exchange with a minimum 2-year follow-up were included. Culture data were semi-quantitatively scored with the total Cutibacterium score (TShCuS). Two groups were compared: patients with a High Cutibacterium Load (HCL) group and those with Low Cutibacterium Load (LCL) group. PROs and revision rates were compared, and a multivariable analysis was conducted.

Results: Of 68 male patients that underwent revision shoulder arthroplasty, 29 (42.6%) met the inclusion criteria for the HCL group, while 27 patients (39.7%) were in the LCL group. Mean follow-up was 4.7 ± 3 years. Patients with intraoperative humeral loosening had an 18.4 times increased risk of having high Cutibacterium loads (95% CI 2.1-154.4, p < 0.001). There were no significant differences in PROs or re-revision rates between the HCL and LCL groups.

Conclusions: Intraoperative humeral loosening was independently associated with high Cutibacterium loads found at the time of revision shoulder arthroplasty. Male patients with high bacterial loads treated with complete single stage exchange and antibiotics had patient-reported outcomes similar to those of patients with minimal to no load.

Level Of Evidence: III.