Chronic nonbacterial osteomyelitis in childhood: prospective follow-up during the first year of anti-inflammatory treatment

Abstract

Introduction: Chronic nonbacterial osteomyelitis (CNO) is an inflammatory disorder of unknown etiology. In children and adolescents CNO predominantly affects the metaphyses of the long bones, but lesions can occur at any site of the skeleton. Prospectively followed cohorts using a standardized protocol in diagnosis and treatment have rarely been reported.

Methods: Thirty-seven children diagnosed with CNO were treated with naproxen continuously for the first 6 months. If assessment at that time revealed progressive disease or no further improvement, sulfasalazine and short-term corticosteroids were added. The aims of our short-term follow-up study were to describe treatment response in detail and to identify potential risk factors for an unfavorable outcome.

Results: Naproxen treatment was highly effective in general, inducing a symptom-free status in 43% of our patients after 6 months. However, four nonsteroidal anti-inflammatory drug (NSAID) partial-responders were additionally treated with sulfasalazine and short-term corticosteroids. The total number of clinical detectable lesions was significantly reduced. Mean disease activity estimated by the patient/physician and the physical aspect of health-related quality of life including functional ability (global assessment/childhood health assessment questionnaire and childhood health assessment questionnaire) and pain improved significantly. Forty-one percent of our patients showed radiological relapses, but 67% of them were clinically silent.

Conclusions: Most children show a favorable clinical course in the first year of anti-inflammatory treatment with NSAIDs. Relapses and new radiological lesions can occur at any time and at any site in the skeleton but may not be clinically symptomatic. Whole-body magnetic resonance imaging proved to be very sensitive for initial and follow-up diagnostics.

Figures

Figure 1

Correlation of the number of radiological lesions with the erythrocyte sedimentation rate. Regression line depicts the 95% confidence interval. Results presented as absolute numbers. Correlation coefficient r = 0.5, P < 0.0009. ESR, erythrocyte sedimentation rate.

Figure 2

Whole-body magnetic resonance imaging of chronic nonbacterial osteomyelitis. Whole-body magnetic resonance imaging of one patient with extensive multifocal inflammatory radiological lesions at time of diagnosis: T2-weighted images with fat suppression (inverse recovery sequences, TIRM). The os sacrum and the acetabulum (all three osseous parts) did show severe signal elevation in the TIRM sequence. Further lesions are seen in the metaphyses of both proximal and distal femurs, proximal tibias and fibulas predominantly in the epiphyses/metaphyses and in the distal tibia and fibula with periosteal edema on the right side, supporting the clinical diagnosis of periostitis and arthritis. Signal alterations/edema in the skeleton of the feet can be noted at the basis of os metatarsale V, os metatarsale I and in the tuber calcanei on the right side; on the left side, the basis and the proximal parts of os metatarsale I and the distal os metatarsale V and the proximal phalanx V are affected.

Figure 3

Clinical course of disease. Results presented as mean of scores indicated. Statistical analysis performed using analysis of variance. CHAQ, childhood health assessment questionnaire.

Figure 4

Course of disease: PedCNO score. Course of disease with the PedCNO30, PedCNO50 and PedCNO70 scores. Results presented as percentages of the absolute numbers of patients.