MRI AS A DIAGNOSTIC GATEKEEPER FOR SURGICAL DECISION-MAKING IN PAEDIATRIC HIP INFECTIONS: A TEN-YEAR SINGLE-CENTRE EXPERIENCE

Limping child represents a diagnostic challenge, with imperative being exclusion of septic arthritis and osteomyelitis. Whilst clinical assessment and inflammatory markers guide initial evaluation, MRI's ability to detect early marrow oedema, effusion, periosteal changes can direct surgical decision-making. To evaluate diagnostic performance of MRI hip in paediatric patients presenting with limp, determine utility in guiding surgical intervention, assess role in avoiding unnecessary operative procedures over a 10-year single-centre period. Retrospective review of paediatric patients undergoing hip/ sepsis screen MRI specifically for suspicion of hip infection at our institution between 2015–2025. MRI findings, operative records, microbiological culture results (joint fluid and blood), and clinical outcomes were retrieved from records. Primary outcome was correlation between MRI findings and decision to proceed to surgical washout. Secondary outcome was MRI's negative predictive value in avoiding unnecessary surgery. 39 patients were included. MRI diagnoses comprised osteomyelitis (7), transient synovitis (6), stress reaction/marrow oedema (3), Perthes disease (2), fracture (2), incidental appendiceal inflammation (2), and normal studies (10). Seven patients (18%) proceeded to surgical washout, all demonstrating MRI features of infection or significant effusion and positive intra operative pus or microbiological result. One patient with minimal MRI infective features returned a positive synovial fluid culture, representing a rare false-negative. MRI supported avoidance of surgical washout in 32 of 39 patients (82%). MRI enabled safe avoidance of surgery in 82% of cases whilst reliably identifying those requiring intervention. Early routine integration within a standardised pathway is advocated, acknowledging rare false-negative limitations.