Vertebral fractures and bone health in patients with chronic non-bacterial osteomyelitis at disease onset: insights from the monocentric CAMELOT cohort

Background: Chronic non-bacterial osteomyelitis (CNO) is a rare autoinflammatory disease characterized by bone pain and sterile bone inflammation. Objectives: This study aimed at describing clinical presentation, laboratory and imaging features, densitometric assessment, and therapeutic approaches in a monocentric CNO cohort. Design: Monocentric retrospective cohort study. Methods: Patients were included in the Chronic non-bActerial osteoMyELitis: A mOnocentric regisTry (CAMELOT) in case of (i) clinical diagnosis of CNO, (ii) the fulfilment of diagnostic/ classification criteria, (iii) at least one medical visit at our institution between June 2004 and June 2024, and (iv) a follow-up of at least 3 months. Results: Fifty-one patients were included in the CAMELOT (mean age at onset 11.14 years, 68.6% females). A total of 39.2% of patients presented an autoimmune comorbidity. Bone pain was invariably present; joint involvement was demonstrated in 9.6% of patients. Most subjects (86.3%) had multifocal disease: the median number of bony lesions per patient was 4. Lumbar spine dual-energy X-ray absorptiometry (DXA) was performed in 14 patients (27.4%), showing a reduced bone mineral density (BMD) (−1.14 ± 1.21 Z-score). A total of 18 patients (35.3%) experienced a fracture on a bony lesional site; 14 patients (27.4%) presented vertebral fractures (VFs) at onset, with multiple VFs in 5 cases (35.7%). BMD Z-scores (−1.7 vs −0.5) were lower in patients with VFs, with a higher rate of “low BMD for age” (37.5% vs 16.7%) compared to patients without VFs. Conclusion: The high prevalence of VF observed in the CAMELOT cohort highlights the importance of enlisting CNO in the diagnostic approach to pediatric patients presenting with VF.