Low Kocher-Caird Scores High Clinical Suspicion: A Diagnostic Dilemma in Pediatric Hip Septic arthritis.

INTRODUCTION: The Kocher and Kocher-Caird criteria support differentiation of septic arthritis from transient synovitis in children with an irritable hip, but their performance varies across populations and may be altered by treatment before referral. This study aimed to describe the clinical, laboratory, imaging, operative, microbiological, treatment, and follow-up characteristics of partially treated children with operatively confirmed purulent septic arthritis of the hip despite normal admission inflammatory markers, and to determine their Kocher-Caird score distribution. MATERIALS AND METHODS: This single-center retrospective descriptive case series was conducted at a tertiary pediatric orthopedic referral center in Northern India from January 01, 2023, to December 31, 2025. It included 35 consecutive children aged 2-15 years who underwent arthrotomy for suspected septic arthritis of the hip. Eligibility required an atraumatic limp, inflammatory parameters (total leucocyte count, erythrocyte sedimentation rate and C-reactive protein) within normal ranges, a high-resolution ultrasonographic effusion, and frank intraoperative pus. Kocher and Kocher-Caird scores were reconstructed from admission records. RESULT: Median age was 8 years, and median symptom duration was 9 days; 29 children (82.9%) had received antibiotics before referral. Twenty children (57.1%) had a score of 0, 12 (34.3%) scored 1 and 3 (8.6%) scored 2; therefore, 32 of 35 children (91.4%; 95% confidence interval 77.6-97.0%) scored 1 or less. Ultrasonography showed a median effusion depth of 7.2 mm, commonly with internal echoes. Cultures were positive in 14 children (40.0%), most often for Staphylococcus aureus. Culture positivity was lower after documented antibiotic exposure (31.0% versus 83.3%, P = 0.028). Two children required repeat washout; infection resolved in all at a median follow-up of 16 months. CONCLUSION: In this selected cohort, normal peripheral inflammatory markers and a low Kocher-Caird score did not exclude operative septic arthritis. Persistent symptoms, serial examination, and ultrasonographic effusion should guide escalation when clinical suspicion remains.