title: Non-ossifying fibroma: natural history with an emphasis on a stage-related growth, fracture risk and the need for follow-up.
abstract: BACKGROUND
  The aim of this study was to assess and present the radiological morphology of the non-ossifying fibroma (NOF), to describe the life span according to the Ritschl-stages in an effort to determine critical stages with regard to pathological fractures and discuss the need for a follow-up.
  
  
  METHODS
  Reports of a consecutive series of 87 patients with 103 NOFs and a mean follow-up of 27 months were analysed according to the Ritschl-stages with regard to age at time of diagnosis, localisation, duration of stage and symptoms.
  
  
  RESULTS
  Mean patient age in our series was 20 years and lesions most frequently affected the long bones of the lower extremity. Nineteen lesions were categorized in stage A, 53 in stage B, 17 in stage C and 14 in stage D. Most lesions were detected incidentally. In six of ten clinically symptomatic patients with an average age of ten years a pathological fracture occurred, and four of them were located in the tibia. All of these were in stage B with a mean length of 44 mm, an average expansion in relation to the bone-diameter of 75 % in transversal and 87 % in sagittal plane. Duration of the stages was variable. In the critical stage B the mean was 21 months.
  
  
  CONCLUSIONS
  The non-ossifying fibroma follows a characteristic radiomorphological course with variable duration of each stage. Stage B lesions were found to be at an increased risk of fracture, and the age range over which fractures occur was wide. No fractures were detected in the other three stages. Follow-up, including clinical survey and imaging, at six to twelve month intervals may therefore be considered in the case of larger stage B lesions until stage C is reached.
authors.affiliation: Department of Orthopaedics and Traumatology, Comprehensive Cancer Centre Freiburg (CCCF), University Medical Centre Freiburg, Hugstetterstr. 55, 79106, Freiburg i. Br., Germany. georg.herget@uniklinik-freiburg.de.|Comprehensive Cancer Centre Freiburg CCCF, University Medical Centre Freiburg, Hugstetterstr. 55, 79106, Freiburg i. Br., Germany. georg.herget@uniklinik-freiburg.de.
authors.forename: Georg W
authors.initials: GW
authors.lastname: Herget
authors.affiliation: Department of Orthopaedics and Traumatology, Comprehensive Cancer Centre Freiburg (CCCF), University Medical Centre Freiburg, Hugstetterstr. 55, 79106, Freiburg i. Br., Germany.
authors.forename: David
authors.initials: D
authors.lastname: Mauer
authors.affiliation: Department of Radiology, University Medical Centre Freiburg, Hugstetterstr. 55, 79106, Freiburg i. Br., Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Krauß
authors.affiliation: Department of Orthopaedics and Traumatology, Comprehensive Cancer Centre Freiburg (CCCF), University Medical Centre Freiburg, Hugstetterstr. 55, 79106, Freiburg i. Br., Germany.
authors.forename: Abdelrehim
authors.initials: A
authors.lastname: El Tayeh
authors.affiliation: Department of Diagnostic and Therapeutic Radiology, St. Josefs Hospital, Sautierstrasse 1, 79104, Freiburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Uhl
authors.affiliation: Department of Orthopaedics and Traumatology, Comprehensive Cancer Centre Freiburg (CCCF), University Medical Centre Freiburg, Hugstetterstr. 55, 79106, Freiburg i. Br., Germany.
authors.forename: Norbert P
authors.initials: NP
authors.lastname: Südkamp
authors.affiliation: Department of Orthopaedics and Traumatology, Comprehensive Cancer Centre Freiburg (CCCF), University Medical Centre Freiburg, Hugstetterstr. 55, 79106, Freiburg i. Br., Germany.|Comprehensive Cancer Centre Freiburg CCCF, University Medical Centre Freiburg, Hugstetterstr. 55, 79106, Freiburg i. Br., Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Hauschild
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D002648:Child; D018450:Disease Progression; D005260:Female; D005350:Fibroma / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000209:etiology*; D005598:Fractures, Spontaneous / Q000000981:diagnostic imaging / Q000209:etiology*; D006801:Humans; D033162:Incidental Findings; D008297:Male; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult
keywords: Follow-up; Imaging; Non-ossifying fibroma; Stages - symptoms