Open Access Research article

Clinical factors affecting pathological fracture and healing of unicameral bone cysts

Hiroshi Urakawa1*, Satoshi Tsukushi1, Kozo Hosono2, Hideshi Sugiura3, Kenji Yamada2, Yoshihisa Yamada4, Eiji Kozawa1, Eisuke Arai1, Naohisa Futamura1, Naoki Ishiguro1 and Yoshihiro Nishida1

Author Affiliations

1 Department of Orthopedic Surgery, Nagoya University Graduate School and School of Medicine, 65 Tsurumai, Showa-ku, Nagoya, Aichi 466-8550, Japan

2 Department of Orthopedic Surgery, Aichi Cancer Center Aichi Hospital, 18 Kuriyado, Kake-machi, Okazaki, Aichi 444-0011, Japan

3 Department of Orthopedic Surgery, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-ku, Nagoya, Aichi 464-8681, Japan

4 Department of Orthopedic Surgery, Nagoya Memorial Hospital, 4-305 Hirabari, Tenpaku-ku, Nagoya, Aichi 468-8520, Japan

For all author emails, please log on.

BMC Musculoskeletal Disorders 2014, 15:159  doi:10.1186/1471-2474-15-159

Published: 17 May 2014



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.


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.


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.


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.

Unicameral bone cyst; Pathological fracture; Healing; Prognosis; Clinical factors