Bone formation by revascularized periosteal and bone grafts, compared with traditional bone grafts.

Three groups of dogs were studied to compare the bone formation obtained with traditional bone grafting techniques, and that obtained with revascularized periosteum or revascularized bone grafts--all in unstressed bone. Revascularized periosteum did not produce a significant amount of bone in this unstressed model. At 4 months the revascularized rib grafts had a slightly greater tolerance to stress at the callus site than traditional bone grafts, but the incidence of non-union was the same. We conclude that the use of revascularized bone grafts should be reserved for situations in which traditional bone grafting techniques are unlikely to be successful.     

Growth potential in onlay bone grafts: a comparison of vascularized and free calvarial bone and suture bone grafts

Vascularized bone grafts are characterized by a viable cell population with osteogenic potential. These features suggest that continued growth can be anticipated following vascularized membranous bone transfer in a growing craniofacial skeleton. The present paper compares the potential for appositional bone growth in vascularized and free calvarial onlay bone grafts. In seven 8-week-old beagles, growth was assessed by direct caliper measurements of graft dimensions intraoperatively and 16 weeks postoperatively. Vascularized grafts demonstrated a 50 to 60 percent increase in size in all dimensions compared to 10 to 20 percent growth in free grafts (p less than 0.01). Microradiography revealed preservation of calvarial bony architecture and minimal resorption in vascularized grafts, while triple-fluorochrome labeling confirmed subperiosteal appositional bone formation. Free grafts were characterized by significant resorption and a delay in subperiosteal bone formation.     

同种异体骨移植治疗大段骨缺损的研究进展

同种异体骨已成为临床上治疗创伤、感染、先天性骨病及肿瘤切除所致的大段骨缺损的重要材料.本文主要从同种异体骨愈合机制、制备保存、临床应用效果、排斥反应及预防方法四个方面就同种异体骨移植治疗大段骨缺损的研究进展作一综述,为临床骨缺损治疗提供理论支持.     

Electrical stimulation of onlay bone grafts

An animal model was developed to determine the ability of capacitively coupled electrical fields to enhance onlay bone graft survival in the craniofacial skeleton. Fifteen male New Zealand white rabbits were divided into control and stimulated groups. Blocks of iliac bone were transplanted as onlay grafts to the mandibular rami. In all animals a capacitor apparatus was attached externally over the right mandibular ramus; however, a 5-V peak-to-peak sinusoidal signal was applied only in the stimulated group. The experimental period was 6 weeks, with a total of 30 days of constant stimulation. Graft resorption in the stimulated animals was decreased a total of 24.8 percent (p less than 0.001). There appeared to be a trend toward decreased graft resorption caused by the apparatus alone, although this was not statistically significant. The electric field alone decreased resorption by 11.5 percent (p less than 0.05). No distinguishing features were demonstrated by fluorescent vital stains or routine histology.     

Injectable polyHIPEs as high-porosity bone grafts

Polymerization of high internal phase emulsions (polyHIPEs) is a relatively new method for the production of high-porosity scaffolds. The tunable architecture of these polyHIPE foams makes them attractive candidates for tissue engineered bone grafts. Previously studied polyHIPE systems require either toxic diluents or high cure temperatures which prohibit their use as an injectable bone graft. In contrast, we have developed an injectable polyHIPE that cures at physiological temperatures to a rigid, high-porosity foam. First, a biodegradable macromer, propylene fumarate dimethacrylate (PFDMA), was synthesized that has appropriate viscosity and hydrophobicity for emulsification. The process of surfactant selection is detailed with particular focus on the key structural features of both polymer (logP values, hydrogen bond acceptor sites) and surfactant (HLB values, hydrogen bond donor sites) that enable stable HIPE formation. Incubation of HIPEs at 37 °C was used to initiate radical cross-linking of the unsaturated double bond of the methacrylate groups to polymerize the continuous phase and lock in the emulsion geometry. The resulting polyHIPEs exhibited ~75% porosity, pore sizes ranging from 4 to 29 μm, and an average compressive modulus and strength of 33 and 5 MPa, respectively. These findings highlight the great potential of these scaffolds as injectable, tissue engineered bone grafts.     

Growth potential in suture bone inlay grafts: a comparison of vascularized and free calvarial bone grafts

The present study investigates transsutural growth in vascularized and free calvarial bone grafts and notes the effects of such growth on craniofacial development. The temporalis myoosseous flap served as a model of vascularized graft. In ten 8-week-old dogs, a standardized skeletal defect, including a segment of the zygomatico-maxillary suture, was created. The defect was reconstructed with a vascularized graft in half the animals and a corresponding free graft in the remaining animals. Growth was assessed by means of serial cephalometric radiography and direct osteometry. Vascularized bone grafts demonstrated persistent transsutural growth following transplantation. Growth at the recipient site was preserved, resulting in less restriction of vertical maxillary development.     

Bone grafts,bone substitutes and orthobiologics

The biology of fracture healing is better understood than ever before, with advancements such as the locking screw leading to more predictable and less eventful osseous healing. However, at times one’s intrinsic biological response, and even concurrent surgical stabilization, is inadequate. In hopes of facilitating osseous union, bone grafts, bone substitutes and orthobiologics are being relied on more than ever before. The osteoinductive, osteoconductive and osteogenic properties of these substrates have been elucidated in the basic science literature and validated in clinical orthopaedic practice. Furthermore, an industry built around these items is more successful and in demand than ever before. This review provides a comprehensive overview of the basic science, clinical utility and economics of bone grafts, bone substitutes and orthobiologics.