Subcutaneous tissue disinfection is more effective than the use of electrocautery in reducing Cutibacterium acnes burden in open shoulder surgery.

Background: Cutibacterium acnes (C. acnes) is a pathogen linked to infections following shoulder surgery. Exposure can occur during surgical dissection and spread in the surgical field through the surgeon's gloves and instruments. Disinfection of the subcutaneous tissue has been shown to reduce its contamination. No evidence has been provided for a decrease in the transmission rate when the dissection is performed with an electrocautery. The aim of this study was to ascertain whether disinfection of subcutaneous tissue can reduce the C. acnes rate in primary open shoulder surgery in comparison with dissection performed with electrocautery. We also wanted to compare the contamination rate of the operating field after electrocautery dissection with those found in the literature. Methods: All patients who qualified for primary open shoulder surgery via a deltopectoral approach were prospectively included in our single-blinded, two-arm randomized clinical trial. For every patient, a skin swab from the surgical area was taken before the standard preparation of the skin. In the disinfection group, the subcutaneous layer was treated with povidone iodine solution after exposure of the deltoid fascia. The cautery group underwent subcutaneous tissue dissection using an electrocautery. After fully exposing the proximal humerus, 5 swabs were collected from various locations for microbiological analysis, following a rigorous protocol. All cultures were incubated for 14 days under both aerobic and anaerobic conditions. Results: Between February 2020 and July 2021, 210 shoulders were enrolled in 2 groups (140 disinfection vs. 70 cautery). The 2 groups showed no significant differences in terms of sex, age, body mass index, or diabetes prevalence. The subcutaneous disinfection protocol led to a significant decrease in the overall positive culture rate of the operating field for all bacteria (P = .001) and specifically for C. acnes (P = .021). The reduction of positive swabs for C. acnes was significant for both the surgeon's gloves (P = .004) and for the subcutaneous tissue (P = .009). C. acnes contamination rate was noted in 26% of patients in the electrocautery group and 13% in the disinfection group after exclusion of the outside scalpel blade sample, which was removed from the scrub nurse's instrument table and therefore no longer used during the procedure. Conclusion: Disinfection of the subcutaneous tissue reduces the contamination rate of C. acnes by a factor of 2 during open shoulder surgery compared with an approach performed with electrocautery and could limit the contamination of the operating field.