Combined Osteomyelitis-Septic Arthritis and Elevated CRP Are Associated With Multiple Surgeries in Paediatric Osteoarticular Infection

Introduction Osteoarticular infections (OAI) in children carry substantial risks, including progressive infection and functional impairment. Early recognition of severe disease is essential, yet often delayed because initial symptoms may be nonspecific. Delayed treatment can lead to refractory infections requiring multiple surgeries. Diagnostic complexity is heightened in Lyme-endemic regions, where Lyme arthritis can mimic septic arthritis, and when misclassified, patients may undergo unnecessary surgical intervention. The aim of this study was to identify demographic, clinical and laboratory characteristics associated with increased odds of requiring multiple surgeries for children admitted with OAI in a Lyme endemic area. Methods We reviewed medical records of all patients <18 years old with an osteoarticular infection to a tertiary pediatric hospital in a Lyme endemic area. Data were abstracted to REDCap. Patients who required ≥2 surgical debridement procedures were compared to those who underwent ≤1 surgery using Fisher's exact tests and Wilcoxon rank-sum tests. We performed univariate logistic regression to identify characteristics associated with need for multiple surgeries. Results A total of 120 pediatric patients with OAI were included in this analysis. Of these, 93 (78%) underwent ≤1 surgical procedure and 27 (22%) required ≥2 surgeries. The age distribution differed significantly between groups (p=0.011). Patients 2-6 years old were less likely to require multiple surgeries compared to younger and older age groups (odds ratio: 0.09 [95% confidence interval: 0.02, 0.5). Infection type was significantly associated with surgical burden (p=0.007). Patients with both osteomyelitis and septic arthritis were most likely to require multiple surgeries (48%), followed by osteomyelitis alone (33%), while those with septic arthritis alone (11%) or Lyme arthritis (7%) had substantially lower rates. There were no significant differences between groups in sex, race, or ethnicity. An admission CRP >5 mg/dL was associated with need for multiple surgeries (OR=3.28 [95% CI: 1.21, 8.86]); no other laboratory abnormalities were associated with increased odds of multiple surgeries. Patients requiring multiple surgeries had significantly longer hospital stays (median 9 days [IQR 6–31] vs. 2 days [IQR 2–5], p<0.001) and a higher median number of surgical procedures (3 [IQR 2–5] vs. 1 [IQR 0–1], p<0.001). Conclusion Combined osteomyelitis-septic arthritis and admission CRP >5 mg/dL are associated with increased risk of multiple surgical interventions in pediatric OAI. Children 2-6 years old are at the lowest risk. These findings may help clinicians identify high-risk patients who warrant closer monitoring and early multidisciplinary surgical planning.