Bone grafts engineered from human adipose-derived stem cells in dynamic 3D-environments.

Modular tissue engineering (TE) is a promising alternative to overcome the limits in traditional TE. In the present study, adipose tissue derived stem cells (ADSC)-laden microcarriers are used as building blocks (microtissues) that self-assemble into macrotissues in a bottom-up approach. These bone grafts were compared with a classical top-down approach (scaffolds). This concept was compared with bone marrow derived stem cells (BMSC) as cell source. Cells were immunophenotypically analyzed, followed by 2D/3D osteogenic differentiation in static/dynamic conditions. The bone graft quality was evaluated by (immuno)histochemistry and gene expression. After 6 weeks of dynamic culturing, scaffolds were highly colonized although not in the center and the osteogenic gene expression was higher in contrast to static cultures. A cell-to-microcarrier ratio of 5 × 10(6) cells-0.09 g microcarriers leaded to aggregate formation resulting in microtissues with subsequent macrotissue formation. ADSC/BMSC on scaffolds showed a downregulation of Runx2 and collagen I, demonstrating the end-stage, in contrary to microcarriers, where an upregulation of Runx2, collagen I together with BSP and osteocalcin was observed. This paper showed that high quality bone grafts (2 cm³) can be engineered in a bottom-up approach with cell-laden microcarriers.

Efeito da desmineralização ácida da interface enxerto-leito na consolidação de enxertos ósseos autógenos em bloco / Influence of acid demineralization of contacting osseous surfaces on the consolidation of autogenous onlay bone grafts

Para testar a hipótese de que a desmineralização in situ das superfícies de contato enxerto-leito, e a forma como o enxerto é estabilizado ao leito, podem influenciar os mecanismos envolvidos na consolidação do enxerto, fragmentos ósseos de 10 mm de diâmetro foram removidos das metáfises proximais tibiais de 36 coelhos (Oryctolagus Cuniculus) e transplantados para uma área adjacente. Na tíbia esquerda dos animais, as superfícies de contato do enxerto e do leito hospedeiro foram desmineralizadas com ácido cítrico pH 1,0 por 3 minutos antes dos enxertos serem fixados ao leito. Na tíbia direita, o transplante do bloco ósseo não foi precedido de desmineralização. Metade dos enxertos foi imobilizada sobre o leito pela superposição de uma membrana não reabsorvível de politetrafluoretileno colada com cianoacrilato ao leito à distância da interface enxerto-leito. A outra metade dos enxertos foi fixada por um parafuso de titânio no centro do enxerto. Assim, foram formados 4 grupos de estudo: membrana (M), membrana + ácido (MA), parafuso (P) e parafuso + ácido (PA). Três animais de cada grupo forneceram espécimes para análise microscópica quantitativa e qualitativa aos 15, 30 e 45 dias de pós-operatório. A análise qualitativa demonstrou que não houve formação óssea na interface em nenhum espécime aos 15 dias e que nos demais períodos, em todos os grupos, a quantidade de tecido ósseo neoformado na interface e seu estágio de maturação aumentaram com o tempo. Ambos os métodos de fixação empregados foram eficientes em manter os enxertos em posição, porém a membrana promoveu menor reabsorção da estrutura do enxerto. A análise quantitativa computadorizada revelou que, aos 30 dias, os grupos MA e PA apresentaram maior área de formação óssea na interface (71,34 ± 12,03%; 56,74 ± 2,15% respectivamente) em relação aos grupos M e P (51,75 ± 11,02%; 43,95 ± 4,05% respectivamente) e superfícies de consolidação óssea mais extensas (93,41 ± 5,95%; 93,73 ± 4,96%...

In order to test the hypothesis that the demineralization "in situ" of contacting surfaces of bone graft/bone bed and the fixation method used for graft stabilization can influence the mechanisms involved in the consolidation of the graft, bone fragments of 10 mm in diameter were removed from the proximal tibial metaphysis of thirty-six male rabbits (Oryctolagus Cuniculus) and transplanted to an adjacent area. In the left tibia of the animals, the contacting surfaces of the graft and host bed were demineralized with citric acid pH 1.0 for 3 minutes before the grafts were fixed to the receptor bed. In the right tibia, the bone block transplantation was not preceded by demineralization. Half of the grafts were immobilized on the bone bed by a nonresorbable polytetrafluoroethylene membrane glued with cyanoacrylate adhesive to the host bed distant from the bone graft-bone bed interface. The other half of the grafts were fixed by a titanium screw in the center of the graft. Thus, four groups were formed: membrane (M), membrane + acid (MA), screw (P) and screw + acid (PA). Three animals from each group provided specimens for quantitative and qualitative microscopic analysis at 15, 30 and 45 days postoperatively. Qualitative analysis showed no significant bone formation at the interface in any specimen of the groups at 15 days and on the other periods in all groups, the amount of newly formed bone at the interface as well as the stage of bone maturation increased with time. Both fixation methods were effective in maintaining the graft in position, but the membrane resulted in less resorption of the graft. Quantitative analysis, performed by means of a computer program for image analysis, showed that at day 30, groups MA and PA, showed greater area of bone formation at the interface (71.34 ± 12.03%; 56.74 ± 2 15%) than groups M and P (51.75 ± 11.02%, 43.95 ± 4.05%) and more osseointegrated bone surfaces (93.41 ± 5.95%, 93.73 ± 4.96%) than those...

Volume changes of iliac crest autogenous bone grafts after vertical and horizontal alveolar ridge augmentation of atrophic maxillas and mandibles: a 6-year computerized tomographic follow-up.

PURPOSE: To evaluate by computerized tomography the long-term volume resorption of autogenous corticocancellous grafted bone harvested from the ilium and used in an alveolar augmentation procedure followed by endosseous dental implant placement. PATIENTS AND METHODS: Eleven maxillary grafts (8 positioned horizontally) and 13 mandibular grafts (10 positioned vertically) were placed in 16 patients. Using software programs, pre- and postsurgical computerized tomographic scans were used to compare volumes of grafts over time (up to 6 yr) to determine the annual percentage of remaining bone and the overall percentage of bone resorption that could be expected. Yearly measurements of volumes and percentages of remaining bone were then compared statistically. RESULTS: At the 6-year survey for blocks grafted in the mandible, an average resorption rate of 87% was obtained; for maxillary grafts at the same survey, complete resorption of the grafts (mean, 105.5%) was recorded. In general, bone resorption appeared slow, except for that recorded in the first 2 years of healing, the only period in which statistical comparisons among all time points showed significant differences for all variables. CONCLUSIONS: Volumetric measurements of the grafts and their related percentages of remaining bone attested to a progressive and unavoidable bone resorption of almost all the grafted bone in the maxilla and mandible. Although the present data were from a heterogeneous group of defects treated with horizontal and vertical procedures, clinicians, when performing alveolar bone augmentation with an autogenous hip bone, should aim at titanium dental implant osseointegration, not only in the augmented bone but also in the native bone below the graft.

Evaluation of a novel reconstituted bone xenograft using processed bovine cancellous bone in combination with purified bovine bone morphogenetic protein.

BACKGROUND: Xenogeneic grafting represents an alternative to autogenous grafting in osseous reconstruction and exhibits many beneficial properties. However, the usefulness of xenogeneic bone relies on necessary processing procedures for removing antigens and viruses, and preserving biological activities simultaneously. By chemical treatment of bovine cancellous bone to make it an antigen-free scaffold, and extraction of bone morphogenetic protein (BMP) from bovine cortical bone, followed by recombination of the scaffold with the BMP, we developed a new grafting material, reconstituted bone xenograft (RBX). METHODS: In this study, scanning electron microscope and energy dispersive X-ray were first employed to observe the structure and components of RBX. Then the biomechanical property was evaluated by applying compression in a materials testing machine. Subsequently, the immunologic evaluation was performed by measuring galactose-alpha-1,3-galactose (α-gal) epitope in vivo and proinflammatory cytokine (TNF-α) secreted by human monocytic cell line (THP-1) in vitro. Finally, this RBX was implanted into segmental radial defects in a rabbit model, and its ability to treat large bone defects was specifically evaluated. RESULTS: Although the compressive strength of RBX was 10% lower than that of unprocessed bovine cancellous bone (UBCB), the basic porous structure and natural components were still kept in this composite. The α-gal xenoantigen level was significantly lower in RBX (P < 0.05) compared with UBCB. Moreover, the TNF-α level was significantly (P < 0.05) reduced compared with UBCB when THP-1 was exposed to RBX. On the other hand, RBX appeared to induce cartilage formation from immature cell populations and resulted in osteogenesis through endochondral-like ossification from 4 to 12 weeks in repairing segmental bone defects. CONCLUSIONS: These results demonstrate that RBX, with its natural microstructure and components, certain mechanical strength and strong osteoinductivity without evoking immune rejection, has significant potential for the treatment of bone defects.

Autogenous bone graft: basic science and clinical implications.

No single biomaterial is optimum for every craniomaxillofacial application. Instead, surgeons should consider the advantages and disadvantages of each alternative in a given clinical situation, and select the material with lowest overall cost and morbidity, and the highest likelihood of success. Autogenous bone is still considered the gold standard for most applications; it becomes vascularized and osseointegrates with surrounding bone, thus minimizing the risk of infection, dislodgement, or break-down. Limitations include added operative time for graft harvest, donor site morbidity, graft resorption, molding challenges, and limited availability, especially in the pediatric population. Numerous alternatives to bone graft have become available to address these limitations; unfortunately, most of these products are expensive, do not osseointegrate, and have unpredictable biologic activity. Understanding the physiologic behavior of autogenous bone graft can help clarify the indications for its use and provide a conceptual framework for achieving the best possible outcome when this alternative is chosen.

Isolating stromal stem cells from periodontal granulation tissues.

Stem cell therapy is a promising area in regenerative medicine. Periodontal granulation tissues are often discarded during conventional surgery. If stromal stem cells can be isolated from these tissues, they can be used for subsequent surgery on the same patient. Fifteen human periodontal granulation tissue samples were obtained from intrabony defects during surgery. Immunohistochemistry (IHC) was carried out on five of the samples to identify STRO-1, a marker of mesenchymal stem cells. Five samples underwent flow cytometry analysis for the same marker. The remaining five samples were characterized by "colony formation unit-fibroblast" (CFU-f) assay and selected for proliferation assay, flow cytometry of stem cell markers, immunocytochemistry (ICC), multipotent differentiation assays, and repairing critical-size defects in mice. The ratio of STRO-1(+) cells detected by IHC was 5.91 ± 1.50%. The analysis of flow cytometry for STRO-1 was 6.70 ± 0.81%. Approximately two thirds of the CFU-f colonies had a strong reaction to STRO-1 in ICC staining. The cells were multipotent both in vitro and in vivo. Mice given bone grafts and stem cells showed significantly better bone healing than those without stem cells. Multipotent stromal stem cells can be isolated from human periodontal granulation tissues. These cells improve new bone formation when transplanted in mouse calvarial defects. Isolating stem cells from relatively accessible sites without extra procedures is clinically advantageous. This study demonstrated that human periodontal granulation tissues contain isolatable multipotent stem cells. The cells may be a good source for autotransplantation in subsequent treatment.

Orbital stress analysis: part II: design and fixation of autogenous bone graft used to repair orbital blowout fracture.

PURPOSE OF THE STUDY: The purpose of this study was to develop a finite element model (FEM) of a human orbit, who experienced a pure orbital blowout fracture, to study the effect of the geometrical mismatch-induced stresses on the orbital floor/graft interface and how to improve the graft design when restoring the orbital floor. MATERIALS AND METHODS: A FEM of the orbit and the globe of 1 patient who experienced pure orbital blowout fracture and treated with autogenous bone graft was generated based on computed tomographic scans. Simulations were performed with a computer using a commercially available finite element software NISA (EMRC, Troy, MI). The FEM was then used to study the effects of changing the geometry, position, material properties, and method of fixation of the autogenous bone graft on its predictions. RESULTS: The factors that had the biggest impact on the predicted principal strain magnitudes were absence of cancellous bone (up to 60%) and bony support of the graft (up to 50%). Applying rigid fixation reduced stresses by 30% posteriorly and by almost 100% anteriorly. Alterations to the geometry of the bone graft, such as an increase in its thickness, increased principal strain magnitudes (up to 42%). CONCLUSIONS: Applying rigid fixation reduced principal stresses significantly. The role of rigid fixation becomes more prominent when there is no bony support posteriorly and/or medially. This study also highlights the importance of preserving cancellous bone, when harvesting and preparing the autogenous bone graft to reconstruct the orbital floor. The possibility that absence of cancellous bone and the resulting stresses may be a source of graft resorption and/or failure cannot be excluded.

Island osteoperiosteal flaps with interpositional bone grafting in rabbit tibia: preliminary study for development of new bone augmentation technique.

PURPOSE: Loss of alveolar vertical height is one of the most challenging conditions in the field of implantology. A few augmentation techniques have been proposed to address this challenge, including guided bone regeneration, alveolar distraction osteogenesis, sandwich osteotomies and autogenous block grafting. This is a pre-clinical study of lengthening the alveolar bone height using a thin osteoperiosteal bone flap, the "island bone flap" or i-flap, to establish vitality, stability and incorporation of the augmentation material after healing. MATERIALS AND METHODS: A rabbit tibia model was designed for this study and included 8 rabbits. An osteoperiosteal osteotomy was performed through the periosteum cutting 1 mm of the outer cortex of the bone in order to elevate a bone flap. The bone flap was detached, and remained attached to the periosteum as a free floating osteoperiosteal flap, and the resultant defect was filled with xenograft. RESULTS: The histological analysis demonstrates formation of maturing trabeculae in the site of the i-flap. In cases of trauma to the bone marrow during the surgical procedure, a centripetal gradient of bone remodeling from the surgical site toward the periphery was evident, while the bony component of the i-flap maintained vital. CONCLUSIONS: Creating a free floating osteoperiosteal flap, used here with interpositional grafting in a rabbit tibia, appears to heal by both appositional modeling and creeping substitution remodeling. Volumetric augmentation persisted despite exuberant bone turnover in this animal model. This technique holds promise as a possible augmentation bone grafting approach for use in alveolar reconstruction.

Microvascular bone grafting: a new long-term solution for intraosseous arteriovenous malformations of the mandible in children.

BACKGROUND: Intraosseous arteriovenous malformations (AVMs) in the maxillofacial area are rarely reported in the current literature. These malformations have been associated with severe hemorrhage resulting in significant morbidity and mortality. The recommended gold standard treatment of AVMs is an endovascular embolization, combined with surgery. Especially in children, disease management remains a challenge for the surgeon due to the process of bone growth. AIM: In this report, we describe our experience with a microvascular bone graft as another possible surgical technique for the treatment of intraosseous AVMs in children. PATIENT AND METHODS: A 15-year-old boy was admitted to our department with a life-threatening hemorrhage due to an AVM of the left mandible. The attempt of an ordinary tooth extraction had lead to the emergency. Several embolizations and surgical interventions were required. Finally, a bony reconstruction with a microvascular bone graft from the right iliac crest was performed in order to achieve a normal form and function of the mandible. Postoperative recovery of the patient was unremarkable, and no recurrence was reported. Dental rehabilitation and a good esthetic outcome were achieved by insertion of dental implants. RESULTS: The performed interventions resulted in a complete anatomic and clinical cure. CONCLUSION: We suggest microvascular bone grafts from the anterior iliac crest as a valuable alternative in the long-term treatment of intraosseous AVMs, especially for extensive defects and in children.

Treatment of recalcitrant, multiply operated tibial nonunions with the RIA graft and rh-BMP2 using intramedullary nails.

Nonunions of the tibia continue to present some of the most difficult challenges in orthopaedic fracture care. Whether the consequence of the initial presenting injury, co-morbidity or subsequent attempts at fixation, the biological environment is often compromised. Compounding this problem is a lack of consensus on the best approach to addressing nonunited tibia fractures, placing them at risk for multiple, and sometimes ill-informed attempts at nonunion repair. We present nine cases of recalcitrant tibial nonunions which had previously undergone 4 or more attempts at repair treated with a protocol using RIA graft, rh-BMP2 and intramedullary nail fixation.

Reconstrucción nasal con cartílago costal de banco de hueso / Nasal reconstruction with rib cartilage graft

Presentamos una serie de reporte de casos de 10 pacientes con deformidad rinoseptal de distinta etiología; traumáticas, infecciosas y quirúrgicas. Estos pacientes presentaban obstrucción nasal como principal síntoma además de la deformidad estética. Los pacientes fueron tomados de la consulta externa del servicio de Otorrinolaringología del Hospital de San José. A los pacientes se les realizó reconstrucción nasal con cartílago costal de banco de hueso, se les practicó un abordaje por técnica abierta y se utilizó el injerto de banco de hueso. Los pacientes fueron seguidos por 7 meses como mínimo y máximo 16 meses. Los pacientes se evaluaron con registro fotográfico pre y posquirúrgicamente. Dentro del periodo de seguimiento no hubo infección del sitio operatorio o extrusión del injerto. La mejoría funcional y estética fueron evaluadas con grado de satisfacción del paciente y del cirujano como buenas-excelentes. La aplicabilidad de la técnica mostró buenos resultados y aplicación en diferentes grupos etarios y etiológicos.

We are presenting a series of case reports of 10 patients with nasal deformity of a varied etiology:traumatic, infectious, and surgical. All these patients exhibited nasal obstruction as their main symptomadditional to aesthetic deformity. All patients were taken from the external consultation of the Otolaryngology service at Hospital de San José. A nasal reconstruction with costal cartilage frombone bank was performed on the patients. The patients were approached through the open techniqueapproach using the graft from the bone bank. Patients were followed at least 7 months and maximum 16 months. Patients were assessed with photographic record pre and post-operatory. During the follow-up period there was no infection of the operatory site nor was there extrusion of the graft. Functional and aesthetic improvement was assessed with good-excellent as the degree of satisfaction of both the patients and the surgeon. The applicability of the technique showed good results as well as its application to various age and etiologic groups.

Principles of bone grafting.

This article reviews the principles of bone healing and bone grafting. There are many different ways to reach the same goal when bone grafting procedures are performed. With all of the available methods and materials, a clear understanding of these basic principles will assist in the selection of a technique for each individual patient.

Effects of mechanical loading patterns, bone graft, and proximity to periosteum on bone defect healing.

The goal of this study is to elucidate whether mechanobiological factors, including mechanical loading patterns, presence of bone graft, and proximity to the periosteum, correlate to de novo tissue generation and healing in critical sized long bone defects, which are enveloped by periosteum in situ and are bridged at 16 weeks, in sheep femora. Quantitative histomorphometric measures of defect cross sections show that, along the axis least able to resist bending loads (minor centroidal axis, CA), bone laid down in the first two weeks after surgery exhibits more mineralization albeit less total area compared to bone along the axis most able to resist bending loads (major CA). Similarly, areas of the cross section along the minor CA show a higher degree of perfusion albeit less total area of perfusion compared to bone along the major CA. Furthermore, proximity to the periosteal niche, in conjunction with the presence of bone graft and predominant loading patterns, relates significantly to the radial distribution of early bone apposition and perfusion of bone at 16 weeks after surgery (linear regression with R(2)>0.80). In the absence of graft, early bone density is relatively evenly distributed in the defect zone, as is the intensity of perfused tissue. As measured by a steeper average slope in intensity of fluorochrome (new bone) distribution between the periosteum and the IM nail, the presence of bone graft retards initial bone formation in the defect zone and is associated with less evenly distributed tissue perfusion (steeper slope) persisting 16 weeks after surgery. Finally, although the mean area of bone resorption is not significantly different within or between groups defined by the presence of graft and/or mechanical loading patterns in the defect zone, the mean area of infilling resorption spaces is significantly higher in areas of the defect zone least able to resist bending (minor CA) but is not significantly related to the presence of bone graft. To our knowledge, the use of the major and minor centroidal axes to relate prevailing mechanical loading patterns to area and density of early bone generation in bone defects has not been reported prior to this study and may provide a new means to assess structure-function relationships in de novo bone generation and healing of bone defects.

Quantitative assessment of the bone morphogenetic protein expression from alternate bone graft harvesting sites.

OBJECTIVE: Bone morphogenetic proteins (BMPs) play important roles in the stimulation of osteogenesis and osteoinduction during bone fracture healing and their expression levels may be important for bone graft efficacy. The objective of this study was to determine if there are variations in the expression of BMPs and their receptors in various bone graft harvesting sites. We analyzed autogenous marrow aspirates obtained from three different graft sites for the mRNA levels of BMPs and their receptors. METHODS: Using real-time polymerase chain reaction, we analyzed the mRNA levels of BMPs and their receptors in autogenous bone marrow aspirates obtained from three different bone graft sites of 10 different human subjects. Collection of autogenous bone marrow from the iliac crest, the proximal humerus, and the proximal tibia was performed using standard sterile techniques in the operating room as part of surgery to treat an established fracture nonunion. RESULTS: The mRNA levels of BMP-2 and BMP-5 were the highest in the bone marrow aspirates from the three different sites, whereas the mRNA levels of the other osteoinductive BMPs (BMP-4, -5, -6, -7, -8, and -9) were lower. The mRNA levels of BMP-3, an inhibitor of osteogenesis, were the lowest in the bone marrow aspirates of all three different sites. There were no statistical significant differences in the mRNA levels of any of the BMPs or their receptors investigated in this study in the bone marrow of the three different sites. CONCLUSION: Because no statistical significant differences in the mRNA levels of the BMPs and their receptors were detected in the bone marrow aspirates from the three different sites, our findings suggest that potential differences of various graft sites in the augmentation of bone healing does not result from different expression levels of BMPs.

Postoperative condylar position by sagittal split ramus osteotomy with and without bone graft.

PURPOSE: The purpose of the present study was to determine how the condylar position is affected by the bone graft in the intersegmental space created by sagittal split ramus osteotomy. PATIENTS AND METHODS: We compared the position of the condyle after sagittal split ramus osteotomy, without the bone graft (control group, n = 30) and with the bone graft (study group, n = 30) using computed tomography with a 2-mm thickness. Using 3-dimensional images and a 3-dimensional computer program, the pre- and postoperative displacement and rotation of the condyle in the axial (rotation and mediolateral movement of the condyle) and sagittal plane (anteroposterior and superoinferior movement of the condyle and rotation of the proximal segment) were measured. In addition, the relationship of the amount of rotation and backward movement of the mandible and the change in the condylar position was analyzed. For the statistical analysis, the t test (P = .05) and Wilcoxon rank sum test were used. RESULTS: No statistically significant differences were found in any of the measurements of the 2 groups. Nevertheless, the mediolateral movement (P = .051) showed a relatively greater apparent difference, although the difference was not statistically significant. The condylar displacement had no relationship to the rotation of the mandible. However, the condylar displacement in relation to the amount of backward movement of the mandible was significant, especially when it was greater than 10 mm of setback. CONCLUSIONS: Using a bone graft in the intersegmental gap of a sagittal split ramus osteotomy is considered an effective clinical method to secure the desirable intersegmental position because it helps to maintain the space with ease. Especially in cases with greater than 10-mm setback of the mandible, it prevents excessive condylar displacement.

Bone regeneration in surgically created defects filled with autogenous bone: an epifluorescence microscopy analysis in rats

Although the search for the ideal bone substitute has been the focus of a large number of studies, autogenous bone is still the gold standard for the filling of defects caused by pathologies and traumas, and mainly, for alveolar ridge reconstruction, allowing the titanium implants installation. OBJECTIVES: The aim of this study was to evaluate the dynamics of autogenous bone graft incorporation process to surgically created defects in rat calvaria, using epifluorescence microscopy. MATERIAL AND METHODS: Five adult male rats weighing 200-300 g were used. The animals received two 5-mm-diameter bone defects bilaterally in each parietal bone with a trephine bur under general anesthesia. Two groups of defects were formed: a control group (n=5), in which the defects were filled with blood clot, and a graft group (n=5), in which the defects were filled with autogenous bone block, removed from the contralateral defect. The fluorochromes calcein and alizarin were applied at the 7th and 30th postoperative days, respectively. The animals were killed at 35 days. RESULTS: The mineralization process was more intense in the graft group (32.09 percent) and occurred mainly between 7 and 30 days, the period labeled by calcein (24.66 percent). CONCLUSIONS: The fluorochromes showed to be appropriate to label mineralization areas. The interfacial areas between fluorochrome labels are important sources of information about the bone regeneration dynamics.

Role of mechanical loading in healing of massive bone autografts.

We assessed healing of a 3.5 cm autograft transport segment, denuded of periosteum, and docked to the healthy distal femur with an intramedullary nail. We hypothesized that healing relates to proximity to the healthy distal femur and to mechanical loading patterns. Total bone area, area of new bone apposition, and quality of new bone formed in the 2 weeks after surgery, and area and degree of perfusion 16 weeks after surgery were measured as a function of proximity and loading patterns (as defined by the major and minor centroidal axes, CA). At 16 weeks, no significant differences in early bone apposition or perfusion were observed as a function of distance from the healthy distal femur. Qualitatively, bone was well perfused, both vascularly and pericellularly, and highly remodeled. When cross-sections were pooled from distal to proximal through the docking zone and normalized for total bone area, significant differences in the amount of early proliferative woven bone were related to loading patterns. In contrast, no differences in normalized perfusion area were attributable to loading patterns. Furthermore, early bone apposition and perfusion decreased with increasing radial distance from the bone surface toward the intramedullary nail. Finally, no differences were observed in areas of resorption within the docking zone compared to baseline levels measured in the control (in bone removed to create the defect zone at the time of surgery). Interestingly, infilling of resorption spaces within docking zone specimens related significantly to predominant loading patterns, where areas within the major CA exhibited significantly more infilling.

Pattern of osteogenesis during onlay bone graft healing.

OBJECTIVE: The aim of this paper was to analyze how healing occurs between onlay bone graft and the mandible cortex. STUDY DESIGN: Autologous and allogeneic corticocancellous bones, harvested from the ilium wing, were grafted at each mandible side of 40 rabbits. One side received platelet-rich plasma (PRP). Killings occurred at 3, 7, 14, 28, and 56 days. Tissues were stained by hematoxylin-eosin and toluidine blue. New bone area was measured at different regions of sections stained with toluidine blue. Wilcoxon test was used to analyze differences among regions and Bonferroni test to analyze the influence of PRP, graft nature, and days. RESULTS: Osteogenesis was higher at the lateral region (P < .05). PRP tended to improve bone neoformation, which was higher at the allogeneic graft. Statistical significance among the different categories of variables-grafts, use of PRP, and days of observation-did not have a linear behavior. A linear behavior of statistical tests was not detected. Bone new formation increased until the 14th day (P < .05). CONCLUSIONS: Onlay grafts heal due to osteogenesis which occurs at the lateral region and between the cortex and host mandible. Allogeneic grafts and PRP tend to improve bone formation.

Platelet-rich plasma diminishes calvarial bone repair associated with alterations in collagen matrix composition and elevated CD34+ cell prevalence.

The interaction between platelets and both type I and III collagens plays an important role in modulating platelet adhesion and aggregation, also contributing to the chemotaxis of CD34+ cells. The interaction with type III collagen can maintain high levels of collagen and alter the biology of bone repair when the PRP is used. The aim of this study was to evaluate the effect of platelet-rich plasma (PRP) and autograft on the presence of type III and type I collagens, the ratio between them, as well as the presence of CD34+ progenitor cells, while comparing these results by means of a histomorphometric analysis of the bone tissue. Four bone defects (8.0mm in diameter and 2.0mm in depth) were produced on the calvarium of 23 rabbits. The surgical defects were treated with either autogenous bone grafts, autogenous bone grafts with PRP and PRP alone. Animals were euthanized at 2, 4 or 6 weeks post-surgery. Histological, histomorphometric and immunohistochemical analyses were performed to assess repair time, as well as the expression of type I and III collagens, and number of progenitor CD34+ cells. Data were analyzed using the ANOVA and Student-Newman-Keuls test (alpha=5%). An enlarged granulation and medullary tissue areas in the PRP groups were observed. The use of PRP in this study hindered bone deposition, also enhanced type III to type I collagen ratio and the chemotaxis of CD34+ progenitor cells, similarly to a thrombogenic effect.

The effect of platelet-rich plasma on early and late bone healing using a mixture of particulate autogenous cancellous bone and Bio-Oss: an experimental study in goats.

Platelet-rich plasma (PRP), containing various growth factors, may speed up wound and bone healing. Using osteoconductive alloplastic materials in reconstructive surgery, the amount of autogenous bone needed can be reduced. The purpose of this experiment was to study the effect of PRP on a mixture of autogenous bone and deproteinized bovine bone mineral (Bio-Oss) particles in goats. Four, round, critical size defects were made in the foreheads of 20 goats. In all goats the defects were filled with a mixture of autogenous particulate cancellous bone and (Bio-Oss) particles, in which 1 ml of PRP was added in two of the four defects. The goats were allocated to four subgroups each containing five goats, which were killed after 1, 2, 6 and 12 weeks. The results of the histological and histomorphometric examination showed that early and late bone healing were not enhanced when PRP was used.