Concordance of three different methods to obtain samples for culture in reverse total shoulder arthroplasty: a prospective study.

Abstract

Purpose: The objective of this study was to analyze the concordance of the results obtained when culturing samples that are obtained with three different methods.

Methods: Prospective study that includes primary Reverse shoulder arthroplasties. From all the patients, 9 cultures were obtained. There were 3 cultures obtained from skin at the beginning of surgery, 3 from the tissue around the insertion of the long biceps on the glenoid side, and 3 from the tissue around the greater tuberosity on the humeral side. At each location, one culture was obtained from a swab, another one was obtained from the instruments on the table, and another one was obtained from a newly-opened set of instruments.

Results: There were 87 patients included, leaving 783 culture samples for the analysis. Of those 783 samples, 69 turned to be positive: 57 were positive for C. acnes, 5 for S. epidermidis, 4 for other coagulase-negative staphylococcus, and 3 were positive for other indolent microorganisms. Comparing the results obtained with the three different methods, the kappa coefficient for all positive cultures was 0.1894 for cultures taken from skin, 0.4891 for cultures from the glenoid and 0.5456 for cultures from the greater tuberosity. Therefore, the kappa coefficient obtained for the three different locations ranged from poor to moderate.

Conclusion: The analysis of the concordance of the samples obtained with swab, tissue cultures taken with the instruments of the table and tissue cultures taken with new sets of instruments lead to different culture results in shoulder arthroplasty.