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Critical Size Defect (critical + size_defect)
Selected AbstractsA new animal model for bone atrophic nonunion: Fixation by external fixatorJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 12 2008Katharina Kaspar Abstract A new small animal model of bone atrophic nonunion was established for investigating the process of bone regeneration by performing cauterization of the periosteum, removal of the local bone marrow, and stabilization with external fixation. The model allows the creation of an atrophic nonunion without the need for a critical size defect. Furthermore, it provides reproducible, well-defined mechanical conditions and minimized physical interference of the implant with the biological processes in the healing zone. Eighty adult Sprague-Dawley rats received an osteotomy of the left femur, stabilized with an external fixator. In half of the animals, the periosteum proximal and distal to the osteotomy was destroyed by cauterization and the adjacent bone marrow was removed (nonunion group). At 2 and 8 weeks after surgery, radiological, biomechanical, histological, and histomorphometrical analyses showed a typical physiological healing in the control group, while the nonunion group was characterized by resorption of the bone ends with some callus formation distant to the osteotomy. At both time points, the callus was composed of significantly less bone and significantly more connective tissue (p,<,0.001). In addition, the torsional strength of the osteotomized femur was significantly less in the nonunion group than in the control group, which was comparable to that of the intact femur (p,<,0.001). In conclusion, the present model allows the induction of an atrophic nonunion without the need of a critical size defect. It is reproducible, provides standardized biomechanical conditions, and allows minimized interaction of the implant with the healing zone. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] In vivo study on the healing of bone defects treated with bone marrow stromal cells, platelet-rich plasma, and freeze-dried bone allografts, alone and in combinationJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2006D. Dallari Abstract The repair of confined trabecular bone defects in rabbits treated by autologous bone marrow stromal cells (BMSC), platelet-rich plasma (PRP), freeze-dried bone allografts (FDBA) alone and in combination (BMSC,+,PRP; FDBA,+,BMSC; FDBA,+,PRP; FDBA,+,PRP,+,BMSC) was compared. A critical size defect was created in the distal part of the femurs of 48 adult rabbits. Histology and histomorphometry were used in the evaluation of healing at 2, 4, and 12 weeks after surgery. The healing rate (%) was calculated by measuring the residual bone defect area. Architecture of the newly formed bone was compared with that of bone at the same distal femur area of healthy rabbits. The defect healing rate was higher in PRP,+,BMSC, FDBA,+,PRP, FDBA,+,BMSC, and FDBA,+,PRP,+,BMSC treatments, while lower values were achieved with PRP treatment at all experimental times. The highest bone-healing rate at 2 weeks was achieved with FDBA,+,PRP,+,BMSC treatment, which resulted significantly different from PRP (p,<,0.05) and BMSC (p,<,0.05) treatments. At 4 weeks, the bone-healing rate increased except for PRP treatment. Finally, the bone-healing rate of FDBA,+,PRP, FDBA,+,BMSC, and FDBA,+,PRP,+,BMSC was significantly higher than that of PRP at 12 weeks (p,<,0.05). At 12 weeks, significant differences still existed between PRP, BMSC, and FDBA groups and normal bone (p,<,0.05). These results showed that the combination of FDBA, BMSC and PRP permitted an acceleration in bone healing and bone remodeling processes. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] Bone tissue engineering in a critical size defect compared to ectopic implantations in the goatJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2004Moyo C. Kruyt Abstract Since the application of the autologous bone graft, the need for an alternative has been recognized. Tissue engineering (TE) of bone by combining bone marrow stromal cells (BMSCs) with a porous scaffold, is considered a promising technique. In this study we investigated the potential of tissue engineered bone to heal a critical sized defect in the goat. Orthotopic bone formation was compared to ectopic bone formation in comparable constructs. TE constructs were prepared from goat BMSCs and porous biphasic calcium phosphate ceramic scaffolds. These constructs and scaffolds without cells were implanted paired in critical sized iliac wing defects. Comparable samples were implanted intramuscularly. After 9 (n = 7) and 12 (n = 8) weeks implantation, the samples were analyzed histomorphometrically. After 9-weeks implantation in the iliac wing defect, significantly more bone apposition was found in the TE condition. After 12 weeks, the defects were almost completely filled with bone, but no significant advantage of TE was determined anymore. This contrasted with the intramuscular samples where TE implants showed significantly more bone at both time points. In conclusion, bone TE is feasible in critical sized defects. However, when appropriate osteoconductive/inductive materials are applied the effect of cell seeding may be temporary. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Effects of various implant materials on regeneration of calvarial defects in ratsPATHOLOGY INTERNATIONAL, Issue 8 2000Sung-Chul Lim The purpose of the present study was to determine the best implant material, the best conditions to substitute absorbable membrane for non-absorbable membrane, and the factors influencing guided regeneration of critical size defects using experimental rats. An 8-mm circular transosseous calvarial bony defect was made and implant materials, such as demineralized freeze-dried bone (DFDB), absorbable membrane (BioMesh; Samyang Co., Seoul Korea), non-absorbable membrane (Millipore filter; Micro Filtration System, MA, USA) or a combination of these materials, was placed on the defect. As for the results of sequential time-based guided bone regeneration, histological, histochemical, immunohistochemical and histomorphometric aspects were observed, and a statistical comparative analysis was performed, with control group of a soft tissue flap. Bone formation was significantly enhanced when DFDB was retained within the defect with a protective absorbable membrane. Inframembranous DFDB-filling was required to prevent membrane collapse and to preserve spaces for bone regeneration. The absorbable membrane which was recommended to overcome the disadvantages of the non-absorbable membrane should remain intact for more than 5 weeks in order for it to be effective. The macrophages recruited by grafts were involved partly in decreasing bone regeneration via the sequential events of releasing fibronectin, and in chemotactic effect of the fibronectin to fibroblasts and collagen lay-down. Thus, the activity of new bone formation was dependent upon the physical barrier effect of the membrane, such as the preserving ability to secure spaces and the suppression ability of early infiltration of collagen and epithelium, inducible ability of inflammation by the implant material, and potential in guiding bone regeneration of the grafts. [source] Bone repair and augmentation using block of sintered bovine-derived anorganic bone graft in cranial bone defect modelCLINICAL ORAL IMPLANTS RESEARCH, Issue 4 2009Tania Mary Cestari Abstract Objective: To histomorphometrically investigate the repair of critical size defects (CSDs) and bone augmentation in cranial walls using block of sintered bovine-derived anorganic bone (sBDAB) graft. Material and methods: Forty guinea-pigs were divided into test (n=20) and CSD control (n=20) groups. In each animal, a full-thickness bone defect with 9.5 mm diameter was made in the frontal bone. The defects were filled with an sBDAB block soaked in blood in the test group and with blood clot in the CSD control group. The skulls were collected at 0 h (n=2) and 30, 90 and 180 days (n=6/group and period) postoperatively. The volume density and total volume of newly formed bone, sBDAB, blood vessels and connective tissue, vertical thickness of removed bone plug, sBDAB block and graft area were evaluated. Results: The vertical thickness of the adapted sBDAB block was 3.8 times higher than that of the removed bone plug and did not show significant difference between periods, filling in average 29.8% of the total graft region. The sBDAB block exhibited complete osseointegration with the borders of the defect at 90 days. At 90 and 180 days, the vertical thickness of the graft was 279% in the average, and the total volume of bone augmentation was, respectively, 78.8% and 148.5% higher compared with the removed bone plug. The defects of the CDS control group showed limited osteogenesis and filling by connective tissue plus tegument. Conclusion: The sBDAB block can be used to promote repair of CSDs and bone augmentation in the craniomaxillofacial region, due to its good osteoconductive and slow resorptive properties. [source] | ||||||||||