Culturing Cutibacterium from deep tissues recovered during revision arthroplasty is important for identifying a periprosthetic infection. The benefits of cultivating explanted components have not been adequately documented. The following questions focused on this research: How do explant cultures compare to deep tissue cultures in terms of culture positivity? How often are explant cultures positive when tissue cultures are negative, and how often are tissue cultures positive when explant cultures are negative? How do explant cultures compare to tissue cultures in bacterial density? The study included 106 anatomic arthroplasties updated over seven years. Cutibacterium culture was performed on explant (humeral head, humeral stem, glenoid) and tissue (collar membrane, humeral canal tissue, periglenoid tissue) specimens. When cultures of an explant and tissue close to the implant were available, we evaluated culture-positive and bacterial density.
Explants had more positive cultures than nearby tissue specimens for most anatomic sites. When tissue samples were negative (23-43%), more explants were culture-positive than when tissue samples were positive (0-21%). Explants had a greater Cutibacterium density than tissues. When they included tissue sample findings, 16% of the shoulders reached our infection treatment criterion (two positive cultures); however when they included explant culture results, an additional 14% of cases – a total of 30% – fulfilled the criteria for infection therapy. Culturing explants in addition to tissue cultures boosted the sensitivity for finding Cutibacterium in revision shoulder arthroplasty in this group of patients.