Mortality and Adverse Joint Outcomes in Adult Patients with Surgically Treated Knee Septic Arthritis

Background and purpose: Septic arthritis is a serious orthopedic surgery and delayed management causes irreparable damages. The knee is the most common site involved in septic arthritis. The purpose of this study was to determine mortality rate, adverse joint outcome and prognostic factors in adult patients diagnosed with septic arthritis of the knee who had undergone debridement surgery. Materials and methods: This retrospective cohort study was carried out using the medical records of all adult patients admitted to Sari Imam Khomeini Hospital and Sari BuAliSina Hospital between 2009 and 2019 who were treated with either arthrotomy or arthroscopic irrigation for acute septic arthritis of the knee. Patients with prosthetic joints were excluded. The rate of mortality was determined. Clinical findings, laboratory evidence, knee radiographs, and the Knee injury and Osteoarthritis Outcome Scores (KOOS) were compared through statistical analysis to identify possible prognostic factors.  Radiographic severity was classified based on the Kellgren-Lawrence grading. Results: We included 31 patients and there were 41.9% female patients (mean age= 51.1±20.56). The most common underlying diseases were hypertension (29%) and diabetes mellitus (25.8%). Staphylococcus aureus was identified in 16.1% of synovial fluid cultures. The mortality rate was 22.6%. Factors influencing mortality included older age (P=0.003), diabetes mellitus (P=0.031), fever (P=0.038), length of hospital stay (P=0.019), high C-reactive protein levels (P=0.002), low creatinine clearance (P=0.003), and type of pathogenic microorganisms (P=0.028). Age was the only factor significantly associated with higher radiographic severity (P=0.014). Conclusion: Septic arthritis is an infectious orthopedic emergency that is associated with a high mortality rate even after joint surgery and debridement. Therefore, proper management and updating information about this disease and its treatment methods are necessary.