title: Radiofrequency ablation of osteoid osteoma in atypical locations: a case series.
abstract: BACKGROUND
  Osteoid osteoma has a nidus surrounded by sclerotic bone with a size usually less than 20 mm. Its diagnosis is made on typical presentation of nocturnal pain and imaging findings. Excision of the niduses, which are often small and difficult to precisely identify, sometimes may result in resection of surrounding normal bone. Minimally invasive percutaneous treatments have been used to try to minimize resection of normal bone. Although minimally invasive radiofrequency ablation generally relieves pain, its ability to relieve pain is less well known in locations other than lower extremity long bones.
  
  
  OBJECTIVE
  We determined the pain relief and complication rates after radiofrequency ablation of osteoid osteomas presenting in atypical locations and followed patients to assess possible recurrence or late complications.
  
  
  METHODS
  We retrospectively reviewed 21 patients with osteoid osteomas in unusual locations (eg, hip, radioulnar joint, and proximal phalanx) in whom we used radiofrequency ablation. Postoperative activities were not restricted for any of the patients. We assessed the time for patients to become symptom free, their activity status, and possible recurrence or complications. The minimum clinical followup was 12 months (mean, 27.8 months; range, 12-37 months).
  
  
  RESULTS
  All patients became symptom free within 24 hours to 1 week. During followup, none of the patients experienced recurrence or any major complications.
  
  
  CONCLUSIONS
  Radiofrequency ablation for osteoid osteomas in unusual locations reliably relieves pain with few complications and recurrences at short-term followup.
  
  
  METHODS
  Level IV, case series. See Guidelines for Authors for a complete description of level of evidence.
authors.affiliation: Noor Medical Imaging Center, Shahid Yousefian St, Motahari St, Tehran, Iran. akhlaghpoor@nmri-ir.com
authors.forename: Shahram
authors.initials: S
authors.lastname: Akhlaghpoor
authors.forename: Alireza
authors.initials: A
authors.lastname: Aziz Ahari
authors.forename: Abbas
authors.initials: A
authors.lastname: Arjmand Shabestari
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Alinaghizadeh
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local; D010017:Osteoma, Osteoid / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery*; D010146:Pain / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery; D011183:Postoperative Complications; D015641:Radiography, Interventional; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult