Factors associated with subsequent surgery after septic arthritis of the knee in children

BACKGROUND: Septic arthritis of the knee in children is a challenging problem. Surgical debridement is an established treatment, but there is a paucity of literature on long-term prognosis. AIM: To determine the rates and factors associated with return to surgery (RTS) and readmission after index surgical debridement for septic arthritis of the knee in children. METHODS: This is a retrospective cohort study that utilizes data from the Healthcare Cost and Utilization Project (HCUP). We included patients between ages 0 to 18 years that underwent surgical debridement for septic arthritis of the knee between 2005 and 2017. Demographic data included age, gender, race, hospital type and insurance type. Clinical data including index admission length of stay (LOS) and Charlson Comorbidity Index (CCI) were available from the HCUP database. Descriptive statistics were used to summarize the data and univariate and multivariate analyses were performed. RESULTS: Nine-hundred thirty-two cases of pediatric septic knee were included. This cohort was 62.3% male, with mean age of 9.0 (± 6.1) years. Approximately 46% of patients were white and approximately half had Medicaid insurance. Thirty-six patients (3.6%) required RTS at a minimum of 2 year after index surgery, and 172 patients (18.5%) were readmitted at any point. The mean readmission LOS was 11.6(± 11.3) d. Higher CCI was associated with RTS (P = 0.041). There were no significant associations in age, gender, race, insurance type, or type of hospital to which patients presented. Multivariate analysis showed that both increased CCI (P = 0.008) and shorter LOS (P = 0.019) were predictive of RTS. CONCLUSION: Septic arthritis of the knee is an important condition in children. The CCI was associated with RTS at a minimum of 2 years after index procedure. No association was found with age, gender, race, insurance type, or hospital type. Shorter LOS and CCI were associated with RTS in multivariate analysis. Overall, risk of subsequent surgery and readmission after pediatric septic knee arthritis is low, and CCI and shorter LOS are predictive of RTS.