Purpose or Case Report: Intra-articular osteoid osteomas are uncommon and occur in only 10-13% of cases. Intra-articular osteoid osteomas may not demonstrate typical clinical features and feature subtle radiographic differences when compared to extra-articular osteoid osteomas. Radiofrequency ablation (RFA) has been found to be a safe and reliable method of treating osteoid osteomas. The possible complications of RFA include bleeding, muscle burn, and in cases of intra-articular osteoid osteoma, septhic arthritis. In this study, we evaluated the efficacy of radiofrequency ablation (RFA) of intra-articular osteoid osteomas at a single tertiary pediatric center.
Methods & Materials: An IRB approved retrospective analysis was performed for patients who underwent RFA of osteoid osteomas over a ten year period. Records were reviewed for: demographics, lesion site, lesion histology, RF probe and ablation technique, technical success, clinical success, clinical follow-up, and complications.
Results: Fifty-four cases of RFA of osteoid osteomas were identified. Of these, fourteen (7 males and 7 females with average age of 12.29 +/- 3.40 years, range: 7.6 – 20.1 years) were identified as intra-articular osteoid osteomas – proximal femur (11), acetabulum (1), proximal ulna (1), and lateral patellar facet (1). The average lesion size was 8.57 mm in maximum diameter. A technical success rate of 100% was achieved. Three RF electrodes were used: the Cool-Tip (Covidien, Mansfield, MA) and the Soloist and LeVeen (both Boston Scientific, Natick, MA). Diagnostic rate of biopsy was 64%. Clinical follow-up was available in all cases, with an average follow-up time of 28.85 months (+/- 23.17 months, range 1-94 months). All patients were asymptomatic on initial follow-up post ablation. There were no cases of septic arthritis. Recurrence occurred in one patient, successfully treated with repeat radiofrequency ablation. Another patient redeveloped pain without a recurrent lesion identified on CT.
Conclusions: Treatment of intra-articular osteoid osteomas with radiofrequency ablation in the pediatric population is a safe and effective technique with high technical success and low rate of septic arthritis.