title: Establishment of reproducible, critical-sized, femoral segmental bone defects in rats.
abstract: Development of new treatment methodologies for bone nonunion requires validated experimental models for their application into tissue engineering approaches. Critical-sized bone defect (CSBD) models identify the smallest size at which tissue defects fail to completely heal during the experimental period. The purpose of this study was to systematically determine a CSBD in rat femurs using external fixation. Thirty Fischer 344 rats were equally divided into six groups. Bone defects of 1, 2, 3, 4, 5, and 6 mm were created in the diaphysis of the femur, before external fixation. Defects were evaluated radiographically at weekly intervals and histologically at the predefined healing period of 8 weeks. Defects of 4 mm or more failed to achieve union in our model. Nonunions were characterized by the absence of a bridging callus and filling of the defect with fibrous and muscle tissue. Radiographically, bone ends in nonunions were rounded up to 4 weeks postsurgery. Our systematic approach for identification of a CSBD in rat femurs, revealed that externally fixed defects of 4 mm and larger, failed to heal within the 8-week time frame.
authors.affiliation: 1 Department of Orthopaedic Surgery, Teikyo University School of Medicine , Tokyo, Japan .
authors.forename: Kenji
authors.initials: K
authors.lastname: Sato
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Noriko
authors.initials: N
authors.lastname: Harada
authors.forename: Satoshi
authors.initials: S
authors.lastname: Abe
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsushita
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Yamanaka
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kaneko
authors.forename: Yuhiro
authors.initials: Y
authors.lastname: Sakai
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology*; D005599:Fractures, Ununited / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D011859:Radiography; D011916:Rats, Inbred F344; D015203:Reproducibility of Results