Clinical and laboratory profile in confirmed vs. suspected septic arthritis patients and its relevance in decision making: A comparative cross-sectional study

PURPOSE: There were 10%–30% of patients with adult-onset septic arthritis (SA) exhibiting sterile synovial fluid (SF), and the uncertainty in the determining diagnosis of these patients posed a challenge in management. The purpose of this study was to investigate the differences between confirmed (Newman A) and suspected (Newman B & C) SA in adults. METHODS: This was a descriptive study with a cross-sectional study design conducted at a tertiary referral centre from July 2016 to February 2019. Patients aged over 18 years presented to the emergency department with clinical features suggestive of SA and were scheduled to undergo arthrotomy and joint lavage by the treating surgeon were included in the study. Patients with prosthetic joint infections and open joint injuries were excluded. Patients’ demographic data, clinical features and laboratory parameters were collected. The clinical and laboratory profile (blood and SF) of the adult patients presenting with features suggestive of SA based on Newman criteria was statistically analyzed by SPSS version 20 software and Microsoft Excel. The categorical variables were expressed as proportions while the continuous variables were expressed as mean (SD) or median (IQR) depending upon the normality of distribution. The difference between the two groups for categorical variables was assessed using the Chi-square test and the difference for continuous variables was assessed using the unpaired t-test and the Mann-Whitney test depending upon normality. A p value < 0.05 was considered significant. RESULTS: Thirty-six patients were divided into confirmed (n = 19) or suspected (n = 17) SA for assessment based on SF culture. The median (IQR) age of the patients was 50 years (37–60 years). There was no significant difference in demographic, clinical and laboratory parameters between the concerned groups. Eight patients presented with fever. Among the confirmed SA cases, 8 were negative for C-reactive protein and 6 had synovial white blood cell count <50,000. Staphylococcus species were isolated in 8 cases. The most common risk factors for SA were chronic kidney disease (25.0%), diabetes mellitus (25.0%), pharmacologic immunosuppression (16.7%), recent joint surgery (11.1%) and distant site infection (11.1%). CONCLUSION: SA is an orthopaedic emergency that needs prompt and aggressive treatment to prevent catastrophic complications. Confirmed and suspected cases of SA exhibit similar demography, clinical features and laboratory parameters at presentation which may mislead the treating surgeon. Management should be based on sound clinical judgment in the event of failure to culture microorganisms.