title: Clinical factors affecting pathological fracture and healing of unicameral bone cysts.
abstract: BACKGROUND
  Unicameral bone cyst (UBC) is the most common benign lytic bone lesion seen in children. The aim of this study is to investigate clinical factors affecting pathological fracture and healing of UBC.
  
  
  METHODS
  We retrospectively reviewed 155 UBC patients who consulted Nagoya musculoskeletal oncology group hospitals in Japan. Sixty of the 155 patients had pathological fracture at presentation. Of 141 patients with follow-up periods exceeding 6 months, 77 were followed conservatively and 64 treated by surgery.
  
  
  RESULTS
  The fracture risk was significantly higher in the humerus than other bones. In multivariate analysis, ballooning of bone, cyst in long bone, male sex, thin cortical thickness and multilocular cyst were significant adverse prognostic factors for pathological fractures at presentation. The healing rates were 30% and 83% with observation and surgery, respectively. Multivariate analysis revealed that fracture at presentation and history of biopsy were good prognostic factors for healing of UBC in patients under observation.
  
  
  CONCLUSIONS
  The present results suggest that mechanical disruption of UBC such as fracture and biopsy promotes healing, and thus watchful waiting is indicated in these patients, whereas patients with poor prognostic factors for fractures should be considered for surgery.
authors.affiliation: Department of Orthopedic Surgery, Nagoya University Graduate School and School of Medicine, 65 Tsurumai, Showa-ku, Nagoya, Aichi 466-8550, Japan. urakawa@med.nagoya-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Urakawa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsukushi
authors.forename: Kozo
authors.initials: K
authors.lastname: Hosono
authors.forename: Hideshi
authors.initials: H
authors.lastname: Sugiura
authors.forename: Kenji
authors.initials: K
authors.lastname: Yamada
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Yamada
authors.forename: Eiji
authors.initials: E
authors.lastname: Kozawa
authors.forename: Eisuke
authors.initials: E
authors.lastname: Arai
authors.forename: Naohisa
authors.initials: N
authors.lastname: Futamura
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nishida
mesh_terms: D000293:Adolescent; D000328:Adult; D001845:Bone Cysts / Q000000981:diagnostic imaging* / Q000628:therapy; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D017102:Fracture Healing / Q000502:physiology; D050723:Fractures, Bone / Q000000981:diagnostic imaging* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult