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

objectiveTo identify the clinical characteristics of and risk factors for pathological fractures secondary to osteoarticular infections (OAI) in children.

methodsWe 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.

resultsThe 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).

conclusionYounger 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.