What is the clinical impact of positive cultures at the time of primary total shoulder arthroplasty?

BACKGROUND

Cultures taken at the time of primary shoulder arthroplasty are commonly positive for Cutibacterium acnes. Despite our limited understanding of the clinical implication of deep tissue inoculation from dermal colonization, significant efforts have been made to decolonize the shoulder prior to surgery. The purpose of this study is to determine differences in clinical outcomes based on culture positivity at the time of primary shoulder arthroplasty.

METHODS

A series of 134 patients who underwent primary anatomic or reverse total shoulder arthroplasty and had intraoperative cultures obtained via a standard protocol were included. In each case, 5 tissue samples were collected and processed in a single laboratory for culture on aerobic and anaerobic media for 13 days. Minimum 2-year functional outcomes scores (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES] and Single Assessment Numeric Evaluation [SANE]) and reoperation data were analyzed.

RESULTS

Forty-two (31.3%) patients had positive cultures (30 C acnes and 21 with at least 2 positive cultures) at the time of surgery. There was no statistically significant difference in postoperative functional outcome scores (ASES: 82.5 vs. 81.9; P = .89, SANE: 79.5 vs. 82.1; P = .54) between culture-positive and culture-negative cohorts. There were no cases of infection. Two patients (4.8%; 2/42) with positive cultures required reoperation compared with 4 patients (5.6%; 4/71) without positive cultures.

CONCLUSION

The apparent colonization by nonvirulent organisms in patients undergoing primary shoulder arthroplasty does not appear to have a clinically significant effect on functional outcomes or need for repeat surgery in the short term.