Analysis of risk factors for concurrent osteomyelitis in children with septic arthritis: A retrospective cohort study.

BACKGROUND: The early differentiation of septic arthritis (SA) with concomitant osteomyelitis (OM) from isolated SA is a critical diagnostic challenge in pediatric orthopedics. This study aimed to identify clinical and laboratory risk factors for concurrent OM in children with SA.

METHODS: We conducted a retrospective cohort study of 132 children surgically treated for SA at our institution between January 2016 and December 2023. Patients were dichotomized into two groups: isolated SA (n = 66) and SA with concurrent OM (SA + OM, n = 66). We collected demographic, clinical, and laboratory data, including time from symptom onset to admission and surgery, time from admission to surgery, prior parenteral antibiotic use, presence of septic shock, preoperative maximum temperature, and microbiological findings. Univariable analyses were performed using Chi-square tests, Mann-Whitney U tests, or independent t-tests. Variables with statistical significance were entered into a multivariable logistic regression model to identify independent predictors of concurrent OM.

RESULTS: Univariable analysis revealed significant differences between the isolated SA and SA + OM groups in time from onset to admission (4.98 ± 2.88 vs. 6.21 ± 3.32 days, P = 0.029), time from onset to surgery (5.50 ± 3.41 vs. 8.02 ± 6.56 days, P = 0.007), time from admission to surgery (12.5 ± 6.8 vs. 43.5 ± 12.4 h, P < 0.001), presence of septic shock (3.0% vs. 12.1%, P = 0.048), preoperative maximum temperature (38.9 ± 0.70 vs. 39.20 ± 0.68 °C, P = 0.008), and infection with Staphylococcus aureus (21.2% vs. 43.9%, P = 0.005). After multivariable logistic regression analysis, three independent risk factors for concurrent OM were identified: time from onset to surgery >7.5 days (Adjusted Odds Ratio [aOR] 3.96, 95% Confidence Interval [CI] 1.07-14.69; P = 0.039), preoperative maximum temperature > 38.65 °C (aOR 3.43, 95% CI 1.46-8.07; P = 0.005), and infection with S. aureus (aOR 3.17, 95% CI 1.38-7.27; P = 0.007).

CONCLUSION: Delayed surgical intervention (>7.5 days from onset), high preoperative fever (>38.65 °C), and infection with S. aureus are significant independent predictors of concurrent osteomyelitis in children with septic arthritis. Clinicians should maintain a high index of suspicion for OM in patients presenting with these risk factors and consider advanced imaging to guide appropriate surgical management.