Mark Coventry Award: Human Knee Has a Distinct Microbiome: Implications for Periprosthetic Joint Infection.

BACKGROUND: Pathogens causing prosthetic joint infection (PJI) are thought to gain access to the knee during surgery or from a remote site in the body. Recent studies have shown that there is a distinct microbiome in various sites of the body. This prospective study, and first of its kind, was set up to investigate the presence of possible microbiome in human knee and compare the profile in different knee conditions.

METHODS: We obtained synovial fluid from 65 knees (55 patients) with various conditions that included normal knee, osteoarthritis (OA), aseptic revision, and those undergoing revision for PJI. The contralateral knee of patients who had a PJI were also aspirated for comparison. A minimum of 3 milliliters of synovial fluid was collected per joint. All samples were aliquoted for culture and next-generation sequencing analysis.

RESULTS: The highest number of species was found in native osteoarthritic knees (P ≤ .035). Cutibacterium, Staphylococcus, and Paracoccus species were dominant in native nonosteoarthritic knees, and meanwhile a markedly high abundance of Proteobacteria was observed in the osteoarthritic joints. Moreover, the contralateral and aseptic revision knees showed a similar trend in bacterial composition (P = .75). The sequencing analysis of patients who had PJI diagnosis, confirmed the culture results.

CONCLUSION: Distinct knee microbiome profiles can be detected in patients who have OA and other knee conditions. The distinct microbiome in the knee joint and the close host-microbe relationships within the knee joint may play a decisive role in the development of OA and PJI.