title: [Natural history and biologic mechanism of the transition from grafted bone to extra-cortical bone bridge over porous-coated segmental prostheses].
abstract: The biologic mechanism of extra-cortical bone bridge formation over a porous-coating segmental prosthesis was studied. A 6 cm segment of the femoral diaphysis was bilaterally resected and replaced by a segmental prosthesis in 32 adult dogs. A morselized autogenous bone graft mixed with marrow cells was applied around the prosthesis and the adjacent cortex. The animals were sacrificed at 2, 4, 8 and 12 weeks postoperatively. Tissue samples from the extra-cortical bone formation zone were analyzed by fluorescent and light microscopy and transmission electron microscopy. Active intramembranous new bone formation occurred appositionally. Osteogenic foci were formed in the fibrous tissue by the determined osteogenic precursor cell contained in the marrow cells. Woven bone formation occurred within the matured callus through endochondral ossification. Extra-cortical bone bridges depended on bone/marrow grafts with good vascularity and mechanical stability as important ingredients. Extra-cortical bone bridges were reduced in volume and matured with time.
authors.affiliation: Department of Orthopaedic Surgery, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakao
authors.forename: Y
authors.initials: Y
authors.lastname: Hirasawa
authors.forename: T
authors.initials: T
authors.lastname: Dueland
authors.forename: E Y
authors.initials: EY
authors.lastname: Chao
mesh_terms: D000818:Animals; D016025:Bone Transplantation / Q000502:physiology*; D004285:Dogs; D016348:Osseointegration / Q000502:physiology*; D016062:Porosity; D019736:Prostheses and Implants; D013499:Surface Properties