O2072: Septic Arthritis of the Hip in Neonates: Risk Factors and Long-term Sequelae

Background: Septic arthritis of the hip is associated with a poorer prognosis than that of any other septic joint, with age less than one year being predictive of especially poor outcomes. The purpose of this study is to report on our institutional experience with septic arthritis of the hip in neonates, with particular focus on predictors of poor outcome and need for subsequent surgery.

Methods: Medical record databases at a single pediatric tertiary care center were reviewed for all patients less than 12-months of age treated for hip sepsis from 1981-2021. Patients were excluded if they were older than 12-months, or if initial surgical treatment occurred at an outside institution. Demographics, presenting signs and symptoms, hematology and microbiology data, surgical details, acute treatment course, and long-term follow-up data were analyzed.

Results: We identified 41 patients meeting inclusion criteria. The median and interquartile range for gestational age was 36 [28-38] weeks, with 12 patients considered pre-term. 15 patients required NICU admission, and 15 patients had comorbidities leading to critical condition at birth or time of diagnosis. Median age at diagnosis of hip sepsis was 78 [20-271] days, and 21 (51%) patients were less than 3-months. Causative bacteria included methicillin-sensitive Staphylococcus aureus (16/41), group-B streptococcus (6/41), Streptococcus pneumoniae (5/41), methicillin-resistant Staphylococcus aureus (3/41), non-aureus staphylococci (2/41), group-A streptococcus (1/41), Neisseria meningitidis (1/41), Escherichia coli (1/41), Citrobacter (1/41), and Bacillus (1/41); 4 patients were culture-negative. When analyzed collectively, bacterial organism varied significantly with patient age, with clear differences seen in the organisms infecting neonates less than 3-months old (Figure 1). Of the 19 patients with greater than two-year clinical follow-up, 13 (68%) had occurrence of any one of the following sequelae of infection: hip deformity/dysplasia (12/13), leg-length discrepancy (8/13), gait abnormality (8/13), avascular necrosis (7/13), joint contracture (4/13), persistent pain (4/13), and hip instability (3/13). Eleven patients (58%) required at least one additional surgery for sequelae related to their hip infection. No demographic or clinical variables were statistically significant predictors of negative long-term sequelae or the need for additional surgery.

Conclusion: This study suggests that septic arthritis of the hip in the neonatal period carries with it a high rate of negative sequelae and need for subsequent surgery, information which can be used to better inform families regarding expected treatment course and prognosis. No demographic or clinical variable was shown to be a statistically significant predictor of these sequelae or the need for future surgery. Notably, there were significant differences in the causative bacteria in patients less than 3-months of age versus those 3-12 months of age, which should help to guide empiric antimicrobial therapy for early treatment prior to culture and sensitivity results.