Multicenter Retrospective Study of Musculoskeletal Bacterial Infections of the Pelvis in Children and Factors Associated With the Formation of an Abscess

BACKGROUND: Musculoskeletal bacterial infections of the pelvis (M-BIP) in children are rare and hard to manage and diagnose, often causing treatment delays and case underestimation. Magnetic resonance imaging (MRI) is the best diagnostic tool, and prompt treatment is crucial to prevent complications. This study aims to describe the clinical presentation, diagnostic methods, and treatments used in M-BIP to improve diagnosis and management. METHODS: This retrospective observational study was conducted in 4 centers, including patients under 16 years with M-BIP between 2014 and 2022. Data on demographics, clinical features, biology, imaging and management were collected. For the highly painful forms called M-BIP hyperalgesic syndrome (M-BIP-HS), we proposed an M-BIP-HS definition and evaluated its relevance. RESULTS: We analyzed 52 patients with M-BIP. Pain, fever and limping were the main clinical signs. The median prehospital delay was 3 days (Q1 = 1.75; Q3 = 5). Inflammatory markers were elevated. Staphylococcus aureus (SA) was the most common pathogen. MRI confirmed the diagnosis and potential complications in all cases. Treatment included appropriate analgesics, prolonged antibiotics and, when necessary, surgical drainage. Fifteen patients developed abscesses, experiencing more severe pain, higher C-reactive protein levels and longer intravenous and total antibiotic therapy than those without complications. M-BIP-HS was observed in 30 patients (60%), and 87% of abscess cases presented M-BIP-HS. CONCLUSIONS: M-BIP is a rare musculoskeletal infection, often characterized by delayed diagnosis. It is mainly caused by SA and requires prolonged antibiotic therapy. M-BIP-HS was strongly associated with SA and abscess complications, which may expose the condition. We recommend early MRI when M-BIP-HS is present to optimize management, antibiotic duration and perform surgical drainage if needed.