Clinical characteristics and risk factors for pathological fractures in children with Staphylococcus aureus osteoarticular infections: a retrospective cohort study.

OBJECTIVE: To identify the clinical characteristics of and risk factors for pathological fractures secondary to osteoarticular infections (OAI) in children. METHODS: We conducted a retrospective analysis of 159 children with acute OAI treated at our institution between July 2012 and June 2024. Patients were divided into a pathological fracture group (n = 24) and a no-fracture group (n = 135). Data analyzed included age, sex, time to admission, Pediatric Intensive Care Unit (PICU) admission and length of stay, non-orthopedic admission, disseminated infection, delayed surgery, precipitating factors, initial symptoms, pre-hospital peak temperature, inflammatory markers, extent of infection, affected bone diameter, bacteremia, pathogen (MSSA or MRSA) and susceptibility, antibiotic use, number of infected sites, surgical method, number of pre-fracture and total surgeries, postoperative fever duration, recurrent fever, length of stay, and number of hospitalizations. RESULTS: The median time to pathological fracture was 55 days, which was significantly positively correlated with age (r = 0.719, P < 0.001). Children aged ≤ 49.5 months constituted the largest proportion of the fracture group (70.8%), followed by children aged 7-15 years (29.2%). The femur was the most commonly affected bone (29.2%), followed by the fibula (25.0%) and tibia (20.8%). Univariate analysis revealed that the pathological fracture group had a higher proportion of children aged ≤ 49.5 months, higher rates of bacteremia, disseminated infection, and PICU admission, more frequent surgical delays, a greater number of pre-fracture and total surgical procedures, more hospitalizations, longer postoperative fever duration, a larger extent of infection, and a smaller affected bone diameter (all P < 0.05). C-reactive protein (CRP) and procalcitonin (PCT) levels were also significantly elevated in the fracture group (P < 0.05). Conversely, no significant differences were found in sex, age as a continuous variable, PICU stay duration, non-orthopedic admission, precipitating factors, pre-hospital symptom duration, initial symptoms, pre-hospital peak temperature, concurrent septic arthritis, number of osteomyelitis sites (≥ 2 or ≥ 3), number of total infected sites (≥ 3), surgical method, recurrent fever, white blood cell (WBC) count, neutrophil percentage (NE%), neutrophil count (NE), erythrocyte sedimentation rate (ESR), or the time for these markers to normalize. Antimicrobial susceptibility and usage patterns were also similar between groups (all P > 0.05). Binary logistic regression analysis identified disseminated infection (OR 22.6), age ≤ 49.5 months (OR 13.8), elevated PCT, a larger extent of infection, and a smaller affected bone diameter as independent risk factors for pathological fracture (all P < 0.05). CONCLUSION: Younger age is a critical determinant for earlier and more rapid development of pathological fractures in pediatric OAI. Age ≤ 49.5 months, disseminated infection, elevated PCT, a larger extent of infection, and a smaller diameter of the affected bone are independent predictors of this severe complication. Prophylactic immobilization with a cast or brace should be strongly considered for patients with these risk factors to prevent fracture and subsequent displacement.