Use of osteogenic bone-marrow precursor cells for reparative osteogenesis in the mandible of experimental animals

Using a model of “bony tissue tunnel defect” produced by the removal of a mandibular incisor in rats, it was found that closing the defect with a bioprosthesis prevented the washing out of osteogenic bone marrow precursor cells, which serve as a substrate for reparative osteogenesis, from the mandibular spongy bone. The reparative process was strongly stimulated if the bioprosthesis contained estrone; in this case, the time required for the tooth socket to be filled with osteogenic tissue was shortened by half. When no bone marrow elements were present in the socket, it was filled with fibrotic connective tissue, the number of bone marrow elements in spongy bone cavities was small, and the mandibular osteogenic tissue underwent atrophy. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 1, pp. 72–75, January, 1995     

The effect of calcium phosphate bone substitute on defect resolution around a rough-surfaced dental implants in dogs

Gap defects often exist around dental implants due to morphological differences between the natural tooth extraction socket and the dental implant. Techniques that can resolve such gap defects include implant surface modification and filling of the defects with bone substitutes. Modified surfaces are generally more effective in this regard than smooth surfaces. Favorable results have also been reported using bone substitutes. This study evaluated the effectiveness of a calcium phosphate (CaP) bone substitute for resolving gap defects around implant surfaces that have been treated with grit blasting and thermal etching. Implants were placed in edentulous areas in four mongrel dogs. Gap defects with a diameter of 2 mm were prepared surgically around the dental implants. These defects were either filled with CaP bone substitute (experimental group) or left unfilled (control group). Defects were evaluated after 8 and 16 weeks of healing. Block specimens were fixed, sectioned, and stained with hematoxylin and eosin. Histometric measurements revealed that healing in gap defects that had been filled with CaP bone substitute proceeded until 16 weeks. Total CaP degradation seemed to occur at between 4 and 8 weeks of healing. In conclusion, a more complete defect resolution was observed in gap defects filled with CaP bone substitute after 16 weeks than after 8 weeks of healing. The beneficial effects of filling in 2-mm gap defects around implants were attributed to the use of CaP bone substitute.     

可注射性生物降解材料PPF修复骨缺损的研究进展

创伤、感染、肿瘤、骨坏死及先天畸形等多种疾病引起的骨缺损临床常见,使得用于骨缺损修复的可注射性生物材料越来越被重视。已开发出骨水泥、天然衍生物及合成聚合物等多种可注射性材料。对可注射性生物降解材料聚富马酸羟基丙酯（poly（propylene fumarate）,PPF）在骨缺损修复方面的研究进展做一综述。     

Differentiation of periodontal ligament fibroblasts into osteoblasts during socket healing after tooth extraction in the rat

Background: The entire socket after tooth extraction is filled with new bone formed by osteoblasts (Obs), but the origin of these Obs remains unknown. Thus, the proliferation and migration of paravascular and endosteal fibroblastic cells and periodontal ligament (PDL) fibroblasts (Fbs) and their differentiation into Obs during socket healing after extraction of the first maxillary molars of the rat were investigated. Methods: The proliferative activity and migration of these cells in the sockets after tooth extraction were studied using radioautography and immunohistochemistry after injection of ³H-thymidine and 5-bromo-2′-deoxy-uridine (BrdU), respectively. Their morphological changes during differentiation was investigated by transmission electron microscopy. Results: One day after tooth extraction, PDL Fbs were the major cell type in the PDL remnant of the socket. Proliferation was low (labeling index (LI) = approximately 2%) until 16 h after tooth extraction but dramatically increased to a maximum level 1 day postextraction (LI = 23%). Between 1 and 2 days, numerous PDL Fbs in the PDL remnant actively migrated into the coagulum and continued to proliferate. On the basis of the high proliferative activity and small number of cellular organelles responsible for procollagen synthesis, these cells appear immature. At 3 days, Fbs contained more cellular organelles and deposited more collagen fibers as they replaced the coagulum with dense connective tissue and the LI declined. At 4 and 5 days, some of the Fbs began to differentiate into Obs, and the proliferation of Fbs dramatically decreased to baseline values. The migration of PDL Fbs and their differentiation into Obs were investigated by labeling with ³H-thymidine or BrdU 1 day after tooth extraction. Heavily labeled Fbs were observed in the PDL remnant at 1 day, in the coagulum at 2 days, and in the dense connective tissue at 3 days. Labeled Obs associated with new bone were seen 4 days after injection. Endosteal and paravascular Fbs also proliferated, but at a lower level and at later time periods than the PDL Fbs. Surprisingly, endosteal and paravascular Fbs contributed only a small population of Fbs to socket healing. Conclusions: These results indicate that PDL Fbs after tooth extraction actively proliferate, migrate into the coagulum, form dense connective tissue, and differentiate into Obs which form new bone during socket healing. © 1994 Wiley-Liss, Inc.     

Plasma transglutaminase factor XIII induces microvessel ingrowth into biodegradable hydroxyapatite implants in rats

Coagulation factor XIII is a member of the transglutaminase-family. Transgluaminases cross-link either fibrin monomers in blood coagulation or extracellular proteins in extracellular matrix formation. In early stages of bone healing migration and proliferation of endothelial cells lead to formation of new vessels. The aim of this study was to investigate the angiogenetic activity of plasma factor XIII in bone defects filled with nanoparticulate hydroxyapatite paste. A critical size defect was created in the tibial head of rats which was not filled in group I. In group II the defect was filled with hydroxyapatite paste, and in group III with hydroxyapatite paste enriched with factor XIII. Ten days after surgery angiogenesis in the defects was assessed using immunohistochemistry and confocal laser scanning microscopy. Ac16 antibody was used to detect activation of factor XIII into factor XIIIA. In defects without biomaterial (group I) vessel-rich connective tissue and diffuse distribution of capillaries was observed. In defects filled with pure hydroxyapatite (group II) formation of capillaries was limited to the host bone-hydroxyapatite interface. In contrast, addition of plasma factor XIII to hydroxyapatite (group III) stimulated formation of vessels within the biomaterial. The current study reveals that factor XIII can improve angiogenesis in hydroxyapatite.     

Low-level laser therapy, at 60 J/cm2 associated with a Biosilicate(®) increase in bone deposition and indentation biomechanical properties of callus in osteopenic rats

We investigate the effects of a novel bioactive material (Biosilicate(?)) and low-level laser therapy (LLLT), at 60 J/cm(2), on bone-fracture consolidation in osteoporotic rats. Forty female Wistar rats are submitted to the ovariectomy, to induce osteopenia. Eight weeks after the ovariectomy, the animals are randomly divided into four groups, with 10 animals each: bone defect control group; bone defect filled with Biosilicate group; bone defect irradiated with laser at 60 J/cm(2) group; bone defect filled with Biosilicate and irradiated with LLLT, at 60 J/cm(2) group. Laser irradiation is initiated immediately after surgery and performed every 48 h for 14 days. Histopathological analysis points out that bone defects are predominantly filled with the biomaterial in specimens treated with Biosilicate. In the 60-J/cm(2) laser plus Biosilicate group, the biomaterial fills all bone defects, which also contained woven bone and granulation tissue. Also, the biomechanical properties are increased in the animals treated with Biosilicate associated to lasertherapy. Our results indicate that laser therapy improves bone repair process in contact with Biosilicate as a result of increasing bone formation as well as indentation biomechanical properties.     

Early bone healing events following rat molar tooth extraction

Healing of the rat tooth extraction socket occurs rapidly, indicating a mechanism for cancellous bone formation occurring swiftly throughout the matrix. The residual periodontal ligament is evident at 2 days after extraction and its rich collagen type III fibre content may form a template for future cancellous bone formation. In the remainder of the early tooth extraction socket, fibronectin staining was generalized. The widespread distribution of fibronectin staining has given rise to speculation that the function of fibronectin may be important in granulation tissue formation, by providing a template matrix for fibroblast migration. Osteoprogenitor cells migrated into the socket from the surrounding bone, and produced decorin and proMMP-13 (procollagenase-3). ProMMP-13 was only expressed at sites of new bone formation, e.g. the border of the recently formed trabecular islands or the periphery of the closing socket. Collagen type I fibres were formed later, and were especially evident at 6 days after extraction. The pattern of distribution of both collagen type I and III fibres were similar as they passed from the bone margin towards the centre of the socket - in the same direction as the forming bone trabeculae. Bone formation occurs by rapid movement of the osteoprogenitor cells along these collagen fibres to allow a rapid healing, rather than that of resorption followed by slow bone deposition.     

Developing porosity of poly(propylene glycol-co-fumaric acid) bone graft substitutes and the effect on osteointegration: a preliminary histology study in rats

Bioresorbable bone graft substitutes could eliminate disadvantages associated with the use of autografts, allografts and other synthetic materials. We investigated a bioresorbable bone graft substitute made from the unsaturated polyester poly(propylene fumarate) which is crosslinked in the presence of soluble and insoluble calcium filler salts. This compact bone graft substitute material develops porosity in vivo by leaching of the soluble filler salts. In attempt to develop materials whose in vivo porosity can be designed such that implant degradation would occur at a rate that remains supportive of the overall structural integrity of the repairing defect site, we studied the early tissue response upon implantation in a bony defect. Three grout formulations of varying solubilities using slightly soluble hydroxyapatite (HA) and soluble calcium acetate (CA) were evaluated in 3 mm holes made in the anteromedial tibial metaphysis of 200 g Sprague Dawley rats (n = 16 per formulation for a total of 48 animals). Grout formulations cured in situ. Animals from each formulation were sacrificed in groups of 8 at 4 days and 3 weeks postoperatively. Histologic analysis of the healing process revealed improved in vivo osteointegration of bone graft substitutes when a higher loading of calcium acetate was employed. All formulations maintained implant integrity and did not provoke sustained inflammatory responses. This study suggested that the presence of a soluble salt permits in vivo development of porosity of a poly(propylene fumarate) based bone graft substitute material.     

Histological findings of long-term healing of the experimental defects by application of a synthetic biphasic ceramic in rats

Calcium phosphate ceramics are generally biocompatible and can develop interactions with human recipient bone. Therefore, they can be widely used in the field of periodontology and dentistry. The purpose of this investigation was to assess the long-term histological bone healing results of experimentally created critical size parietal bone defects in rats. Twelve Wistar rats were used in this investigation. Two 6-mm wide, symmetrical, and circular critical size defects were created in each parietal bone of the animals. While the right defects filled with granular implant (Ceraform), the symmetrical defects were taken as controls. Eighteen months after implantation, rats were killed and defects including the biomaterial with surrounding bone was taken for histological examination. Serial histological sections were cut across the defects and stained for the histological analysis. Both control and Ceraform implanted regions contained dense collagenous tissue. In the implantation site, multinuclear giant cells were observed around the material. On the other hand, there were no necrosis, tumour, and infection in the implantation region. There was no statistical difference between the control and ceraform implanted groups when the bone formation results were compared (p > 0.05). In conclusion, the results revealed that this material is biocompatible and does enhance the new bone building despite the long-term observation period. Although this biphasic ceramic shows within the limits of the study as a less resorptive and not osteoconductive properties, it can be considered as a biocompatible bone defect filling material having a limited application alternative in dentistry and medicine.     

Effect of umbilical cord mesenchymal stem cell in peri-implant bone defect after immediate implant: an experiment study in beagle dogs

Background: For the sake of reducing post extraction resorption, getting optimal positioning of the implant and shortening treatment time, immediate implant placement following tooth extraction has been proposed as a treatment option. However, the large bone defect peri-implant has a negative influence on the process of bone healing. In this study, umbilical cord mesenchymal stem cells (UCMSCs) were transplanted into the bone defect peri-implant inbeagle dogs and the effect of UCMSCs on bone regeneration in peri-implant were assessed. Methods: The mandibular second, third and fourth premolars of 8 beagle dogs were extracted bilaterally. The defects in one side were filled with platelet-rich fibrin (PRF) and then UCMSCs were injected into the defect area, while the defects in the other side were filled with PRF only as control group. The titanium implant was placed into the distal root socket of each extracted tooth. The animals were sacrificed at week 2, 4 and 8 post operative. The bone defects adjacent to the implant which are 4 mm in height, 4 mm in the mesio-distal direction and 3.5 mm in the bucco-lingual direction were made after immediate implant. Histomorphometric analysis was performed using methylene blue-fuchsin acid staining and hematoxylin and eosin (HE) staining to evaluate bone regeneration. Results: The direct bone-to-implant contact (BIC) in the experiment after 4 and 8 weeks was 56.47±1.18% and 76.23±2.08%; and in the control group was40.79±0.65% and 61.17±2.79%, respectively. The percentage of newly formed bone after 2, 4 and 8 weeks was 17.60±1.5%, 49.82±4.02% and 67.16±2.1% in experiment group; and in control group 14.30±1.25%, 37.04±2.29% and 58.83±3.36%, respectively. These results represented significant differences statistically. Conclusion: Intra-bone marrow injection of UCMSCs can promote new bone formation. UCMSCs can be used to as excellent seed cells to repair the large defect peri-implant after immediate implant.     

Developing porosity of poly(propylene glycol-co-fumaric acid) bone graft substitutes and the effect on osteointegration: A preliminary histology study in rats

Abstract -Bioresorbable bone graft substitutes could eliminate disadvantages associated with the use of autografts, allografts and other synthetic materials. We investigated a bioresorbable bone graft substitute made from the unsaturated polyester poly(propylene fumarate) which is crosslinked in the presence of soluble and insoluble calcium filler salts. This compact bone graft substitute material develops porosity in vivo by leaching of the soluble filler salts. In attempt to develop materials whose in vivo porosity can be designed such that implant degradation would occur at a rate that remains supportive of the overall structural integrity of the repairing defect site, we studied the early tissue response upon implantation in a bony defect. Three grout formulations of varying solubilities using slightly soluble hydroxyapatite (HA) and soluble calcium acetate (CA) were evaluated in 3 mm holes made in the anteromedial tibial metaphysis of 200 g Sprague Dawley rats (n = 16 per formulation for a total of 48 animals). Grout formulations cured in situ. Animals from each formulation were sacrificed in groups of 8 at 4 days and 3 weeks postoperatively. Histologic analysis of the healing process revealed improved in vivo osteointegration of bone graft substitutes when a higher loading of calcium acetate was employed. All formulations maintained implant integrity and did not provoke sustained inflammatory responses. This study suggested that the presence of a soluble salt permits in vivo development of porosity of a poly(propylene fumarate) based bone graft substitute material.     

面向即刻种植的种植体的初期稳定性研究

在即刻种植中,良好的种植体初期稳定性是种植成功的关键。牙周炎、外伤以及拔牙时可能导致患者牙槽骨受到破坏出现的骨壁缺损,以及种植体与牙槽窝之间的过盈量,对种植体的初期稳定性均会造成影响。针对临床上种植体周围不同的骨壁缺损程度建立一种新的分类模型,并基于该分类模型,借助有限元分析软件ABAQUS,模拟在不同的过盈量、骨壁缺损程度下面向即刻种植的拟自然牙种植体的初期稳定性。将种植体种植到模拟骨块上,通过种植体稳定性测量仪测量出种植体稳定系数(ISQ),评价种植体的初期稳定性,进行实验比较分析。结果发现:随着过盈量的增加,初期稳定性升高;随着骨缺损程度的增加,初期稳定性下降。在三壁骨缺损下,当种植体与种植窝之间无过盈量时,其ISQ值均小于40;而当过盈量为0.2 mm时,其ISQ值均大于50。这说明,种植体与种植窝之间是否有过盈量,对种植体初期稳定性的影响非常大。当种植体周围是一壁骨缺损时,其ISQ值基本都小于40,此时应增大过盈量来增加种植体的初期稳定性。针对不同程度的骨壁缺损,种植体在设计时所需的过盈量是不同的,这为之后面向即刻种植的个性化拟自然牙种植体的设计提供一定的理论参考。     

重组人骨形态发生蛋白2修饰的组织工程化骨修复眼眶骨折的实验研究

目的 探讨组织工程化骨修复眼眶骨折缺损的治疗效果.方法 体外构建以自体骨髓基质干细胞(BMSC)为种子细胞、可降解吸收的生物材料聚乳酸羟基乙酸聚合物(PLGA)为载体、重组人骨形态发生蛋白2(rhBMP-2)为生长因子的组织工程化骨,将实验动物分为对照组(植入PLGA/rhBMP-2复合物)和实验组(植入组织工程化骨),观察术后1个月、3个月和6个月伤口愈合情况、并发症及眼眶外观、CT影像学和组织学变化.结果 术后所有动物伤口愈合良好,无并发症和眼球凹陷.CT三维成像显示术后3个月实验组的缺损范围[(25.1±6.8) mm2]小于对照组[(55.3±7.7)mm2];术后6个月,实验组的眼眶骨折缺损消失,而对照组仍存在.组织学结果显示,术后1个月即可观察到实验组植入区边缘植入物开始缓慢吸收,少量成骨细胞沿支架长人材料内,而对照组未观察到;术后3个月可见实验组形成条带状新生骨长入将其分割包绕呈交叉排列,材料降解吸收明显高于对照组;术后6个月实验组植人材料完全被降解吸收,同时被新生骨组织取代,植入物与自身骨组织紧密结合,融为一体.而对照组仅部分降解吸收.结论 重组人骨形态发生蛋白2修饰的组织工程化骨具有较强的传导成骨和诱导成骨活性,生物相容性好,材料可完全降解,为骨组织取代,对眼眶骨折缺损具有较好的修复效果.     

骨组织工程中调节巨噬细胞行为促进骨愈合的策略

骨组织工程将材料作为骨再生支架植入缺损局部,帮助完成骨愈合。近年来随着骨免疫学的发展,人们意识到巨噬细胞的免疫应答决定着材料植入的成败。巨噬细胞具有多样性和可塑性,可以根据环境信号极化为M1样(促炎)和M2样(抑炎)表型,在骨愈合的不同阶段发挥作用。巨噬细胞的迁移、增殖、极化等行为对材料特性敏感。对目前在骨组织工程中,通过改变材料的物理特性、表面化学特性以及生物特性,设计能主动调节巨噬细胞行为的材料,从而促进骨愈合的策略进行了概括总结,相关策略包括：增加材料的粗糙度、大孔结合纳米结构、合适的电信号或机械信号、中性或阴离子表面、增加亲水性、利用免疫调节材料或向局部输送免疫活性物质等,以期为设计具有良好免疫调节性的骨组织工程材料提供思路。     

Augmentation of osteoinduction with a biodegradable poly(propylene glycol-co-fumaric acid) bone graft extender. A histologic and histomorphometric study in rats

We investigated the feasibility of enhancing the regeneration of skeletal tissues by augmenting bone grafts with a composite biodegradable bone graft extender material based on the polymer poly(propylene fumarate), PPF. The material was mixed with autograft and allograft and placed directly into a cylindrical metaphyseal defect made in the rat tibia. These formulations were compared to defects without any graft material, autografts, allografts and PPF alone. Nine animals were included in each group. Animals were sacrificed at 1 and 4 weeks postoperatively. Implantation sites were then evaluated using histologic and histomorphometric methods. Results of this study showed that defects did not heal in sham operated animals. In the experimental groups, there was early new woven bone formation in the autograft group with near complete healing of the defect at four weeks. When PPF was used alone, gradual ingrowth of new bone was seen. Mixing of the PPF bone graft extender with either allograft or autograft material resulted in enhancement of new bone formation with both allo- and autograft. However, significantly more new bone formation than in the autograft group was only seen when the PPF bone graft extender was mixed with fresh autograft. Histomorphometry corroborated these findings. Results of this study suggest that a PPF-based material may be used to increase the volume of smaller amounts of bone grafts supporting the concept of "bone graft extenders" by application of engineered biodegradable porous scaffolds.     

Evaluation of the biocompatibility and osteoproductive activity of ostrich eggshell powder in experimentally induced calvarial defects in rabbits

The purpose of this study was to investigate the beneficial effects of particulate ostrich eggshell grafting on the healing of experimentally induced skull defects. The clinical, radiological, histological, and histomorphometrical findings of this material were compared with the results of commercially available demineralized bone matrix (DBM). The study was conducted on 18 adult New Zealand rabbits. One defect served as a control and the remaining ones either were filled with different sized eggshell particles or DBM, in each animal. Clinical and radiological inspections and histologic investigations of the animals were done at the 1st, 3rd, and 6th months of postoperative period. Radiologically, minimal bone regeneration was observed at the empty, control defect sites. The most advanced bone regeneration was in the DBM grafted defects. The eggshell particle grafted defect sites displayed weak bone regeneration at earlier stages, at 1st and 3rd months after operation when compared with demineralized bone matrix. Nevertheless, ossification was satisfactory at 6th month after operation when compared with the control defects. Within the limitations of this study, it was concluded that Ostrich eggshell powder (OSP) is a worth-while bone substitute because it is a safe, cheap, and easily available material. Long-term studies will clarify its possible role in maxillofacial surgery. Further sophisticated experiments should be undertaken before human implantation concerning its osteoproductive activity alone or in combination with other materials.     

Bone regeneration in segmental defects with resorbable polymeric membranes: IV. Does the polymer chemical composition affect the healing process?

Diaphyseal segmental defects 10 mm in length in the radii of 36 skeletally mature rabbits were covered with tubular microporous membranes prepared from poly(L/D-lactide) (18 rabbits) and poly(L/DL-lactide) (18 rabbits) to determine whether chemical composition of the membrane affected the bone healing in the defect. The results of a previous study in which similar defects of the rabbits radii were not covered with membranes or covered with poly(L-lactide) membranes were used as controls. The control defects were rapidly filled with overlying muscle and soft tissues, producing a radio-ulnar synostosis. The osseous activity of control defects was limited to the bone ends. The defects covered with membranes were progressively filled with new bone. At 1 year, complete bone regeneration in the defects covered with the poly(L/D-lactide) membrane was found in 16 cases, no regeneration in 1 animal and pseudoarthrosis in 1 animal. For the poly(L/DL-lactide) membrane there was complete bone regeneration in 17 cases (1 animal died during surgery). The quality of the interface between the new bone and the membrane seemed to be affected by the chemical structure of the polylactides used for membranes preparation. For poly(L/D-lactide), the connective tissue layer entirely separated the new bone from the polymeric membrane. This has been observed before for poly(L-lactide) membranes. In the case of poly(L/DL-lactide) the new bone was formed in some places in direct contact with the membrane and the membrane fragments were osteointegrated. The differences in chemical composition of the polylactide membranes did not have an evident effect on the bone regeneration process in segmental defects of the rabbit radii.     

聚左旋乳酸/壳聚糖纳米纤维三维多孔支架复合骨髓间充质干细胞修复兔骨缺损**△

背景：骨髓间充质干细胞具有向多种间质细胞谱系分化的能力,且支架材料的性能对骨缺损的修复有重要影响。 目的：观察聚左旋乳酸/壳聚糖纳米纤维三维多孔支架复合骨髓间充质干细胞治疗骨缺损。 方法：对骨缺损模型兔分别采用空白植入、髂后上棘自体松质骨移植、聚左旋乳酸/壳聚糖纳米纤维多孔支架移植和复合了骨髓间充质干细胞的聚左旋乳酸/壳聚糖纳米纤维多孔支架移植修复缺损部位。 结果与结论：至移植12周,移植复合了骨髓间充质干细胞的聚左旋乳酸/壳聚糖纳米纤维多孔支架的实验兔的缺损处有骨组织生成,支架材料降解,已完成缺损修复,其修复情况接近松质骨组;髂后上棘自体松质骨移植的实验兔的缺损修复完好,新形成的骨组织较规则;只植入聚左旋乳酸/壳聚糖纳米纤维多孔支架的实验兔有少量骨组织形成,材料部分降解;空白植入的实验兔缺损处无新生骨组织生成,主要由纤维结缔组织填充。说明新型的生物支架材料聚左旋乳酸/壳聚糖纳米纤维三维多孔支架与来源于新西兰大白兔的骨髓间充质干细胞复合培养后,植入同种异体兔股骨髁缺损处,使骨缺损的修复速度加快,表现为较好的体内诱导成骨的作用。     

Reconstruction of the mandible with a poly(D,L-lactide) scaffold, autogenous corticocancellous bone graft, and autogenous platelet-rich plasma: an animal experiment

An animal study is presented, evaluating a method of mandibular reconstruction using a poly(D,Llactide) (PDLLA) scaffold. Six goats underwent a continuity resection of the mandibular angle. The defect was bridged with a preshaped PDLLA scaffold, filled with an autogenous particulate bone graft from the anterior iliac crest, and fixed with two preshaped titanium plates. To accelerate bone healing, autogenous platelet-rich plasma was mixed with the particulate bone graft. All goats had an uneventful healing. The osteosynthesis system withstood immediate loading for a period of 6 weeks until sacrifice. The particulate bone grafts within the PDLLA scaffold, which appeared to be narrowed, showed considerable resorption and replacement by fibrous tissue. In all goats, however, callus formation along the reconstructed segment was seen, providing bony continuity and maintaining the original contour of the reconstructed segment. Thus, the technique used may provide an alternative for reconstruction with revascularized composite flaps with less associated donor site morbidity.