Abstract:Unicompartmental knee arthroplasty (UKA) is an important option in the staged treatment of osteoarthritis of the knee, with the advantages of small incisions, minimal trauma, less bleeding, shorter operative time and shorter hospital stay. However, due to the unique nature of UKA in preserving the healthy side of the tissue, post-operative periprosthetic joint infection (PJI) should be managed more carefully and as early as possible to avoid the destruction of the healthy side of the bone by inflammatory factors, accelerating the process of osteoarthritis. Gram-negative and conditionally pathogenic infections are rare and poorly detected after UKA. Metagenomic next-generation sequencing (mNGS) is an effective tool to identify the pathogenic organisms of infection and can guide the clinical use of targeted drugs. In this paper, we report a case of acute infection with stenotrophomonas maltophilia after UKA for clinical reference.