Native Periosteum Research Articles

A Periosteum-Bioinspired Electrospun Janus Membrane with Antibacterial and Osteogenic Dual Function.

For a guided bone regeneration membrane, it is critical to possess osteogenic capability while inhibiting infection caused by bacteria. Inspired by the bilayer structure of the native periosteum, an electrospun Janus membrane with osteogenic and antibacterial dual-function is fabricated for guided bone regeneration. Hydrophilic moxifloxacin (MXF) and hydrophobic icariin (ICA) are loaded in the nanofibers made of a mixture of polycaprolactone and gelatin at the top and bottom layers, respectively, leading to the opposing hydrophilic/hydrophobic properties of the bilayer Janus membranes. The as-obtained Janus membrane exhibits excellent physical properties (tensile strength > 6.0MPa) and robust biocompatibility, indicating the immense potential as a suitable replacement for the native periosteum. The membrane has a superior surface morphology and outstanding degradation performance in vitro. Besides, the rapid release of MXF and the slow release of ICA can meet the different needs of drug release rates. Only ≈30% ICA is released from the as-obtained Janus membrane after 21 d while almost 80% MXF is released. Mimicking the bilayer structure of the native periosteum, the electrospun Janus membrane containing ICA and MXF exhibits excellent comprehensive properties, which provides a promising strategy for preparing multifunctional scaffolds for tissue engineering.

Irisin-loaded electrospun core-shell nanofibers as calvarial periosteum accelerate vascularized bone regeneration by activating the mitochondrial SIRT3 pathway.

The scarcity of native periosteum poses a significant clinical barrier in the repair of critical-sized bone defects. The challenge of enhancing regenerative potential in bone healing is further compounded by oxidative stress at the fracture site. However, the introduction of artificial periosteum has demonstrated its ability to promote bone regeneration through the provision of appropriate mechanical support and controlled release of pro-osteogenic factors. In this study, a poly (l-lactic acid) (PLLA)/hyaluronic acid (HA)-based nanofibrous membrane was fabricated using the coaxial electrospinning technique. The incorporation of irisin into the core-shell structure of PLLA/HA nanofibers (PLLA/HA@Irisin) achieved its sustained release. In vitro experiments demonstrated that the PLLA/HA@Irisin membranes exhibited favorable biocompatibility. The osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs) was improved by PLLA/HA@Irisin, as evidenced by a significant increase in alkaline phosphatase activity and matrix mineralization. Mechanistically, PLLA/HA@Irisin significantly enhanced the mitochondrial function of BMMSCs via the activation of the sirtuin 3 antioxidant pathway. To assess the therapeutic effectiveness, PLLA/HA@Irisin membranes were implanted in situ into critical-sized calvarial defects in rats. The results at 4 and 8 weeks post-surgery indicated that the implantation of PLLA/HA@Irisin exhibited superior efficacy in promoting vascularized bone formation, as demonstrated by the enhancement of bone matrix synthesis and the development of new blood vessels. The results of our study indicate that the electrospun PLLA/HA@Irisin nanofibers possess characteristics of a biomimetic periosteum, showing potential for effectively treating critical-sized bone defects by improving the mitochondrial function and maintaining redox homeostasis of BMMSCs.

Engineered periosteum-diaphysis substitutes with biomimetic structure and composition promote the repair of large segmental bone defects

The repair of large segmental bone defects remains a big challenge due to limited self-healing capacity of bone. Digging into the structure and composition of natural long bone let us realize that the periosteum cambium on the surface of diaphysis plays a crucial role in bone repair. In this study, we explored the feasibility of using a tissue-engineered periosteum-diaphysis substitute to repair the large segmental bone defects. To create an artificial periosteum cambium, bone marrow mesenchymal stem cells (BMSCs) and endothelial progenitor cells (EPCs) were co-cultured on electrospun silk fibroin (SF) fibrous membranes for mimicking the cellular composition and microstructure of cambium layer of the native periosteum. These SF membranes supported the adhesion and proliferation of both BMSCs and EPCs. In addition, we found that a 1:1 ratio of BMSCs and EPCs supported osteogenesis and angiogenesis optimally. This biomimetic periosteum layer was integrated with artificial diaphysis made of tubular SF scaffolds to construct a biomimetic periosteum-diaphysis substitute. Animal studies confirmed that the biomimetic periosteum-diaphysis substitutes promoted the repair of critical-size bone defects of rabbit radius. Furthermore, the transplanted biomimetic periosteum-diaphysis substitute could prevent the growth of fibrous tissues in the bone defect, and thus reduce the occurrence of nonunion. This study described a promising tissue engineering strategy for the repair of large segmental bone defects.

Periosteum and development of the tissue-engineered periosteum for guided bone regeneration.

BackgroundPeriosteum plays a significant role in bone formation and regeneration by storing progenitor cells, and also acts as a source of local growth factors and a scaffold for recruiting cells and other growth factors. Recently, tissue-engineered periosteum has been studied extensively and shown to be important for osteogenesis and chondrogenesis. Using biomimetic methods for artificial periosteum synthesis, membranous tissues with similar function and structure to native periosteum are produced that significantly improve the efficacy of bone grafting and scaffold engineering, and can serve as direct replacements for native periosteum. Many problems involving bone defects can be solved by preparation of idealized periosteum from materials with different properties using various techniques.MethodsThis review summarizes the significance of periosteum for osteogenesis and chondrogenesis from the aspects of periosteum tissue structure, osteogenesis performance, clinical application, and development of periosteum tissue engineering. The advantages and disadvantages of different tissue engineering methods are also summarized.ResultsThe fast-developing field of periosteum tissue engineering is aimed toward synthesis of bionic periosteum that can ensure or accelerate the repair of bone defects. Artificial periosteum materials can be similar to natural periosteum in both structure and function, and have good therapeutic potential. Induction of periosteum tissue regeneration and bone regeneration by biomimetic periosteum is the ideal process for bone repair.ConclusionsPeriosteum is essential for bone formation and regeneration, and it is indispensable in bone repair. Achieving personalized structure and composition in the construction of tissue engineering periosteum is in accordance with the design concept of both universality and emphasis on individual differences and ensures the combination of commonness and individuality, which are expected to meet the clinical needs of bone repair more effectively.The translational potential of this articleTo better understand the role of periosteum in bone repair, clarify the present research situation of periosteum and tissue engineering periosteum, and determine the development and optimization direction of tissue engineering periosteum in the future. It is hoped that periosteum tissue engineering will play a greater role in meeting the clinical needs of bone repair in the future, and makes it possible to achieve optimization of bone tissue therapy.

Isolation and Culture of Periosteum-Derived Progenitor Cells from Mice.

This chapter describes the methods of isolation of mouse periosteal progenitor cells. There are three basic methods utilized. The bone grafting method was developed utilizing the fracture healing process to expand the progenitor populations. Bone capping methods requires enzymatic digestion and purification of cells from the native periosteum, while the Egression/Explant method requires the least manipulation with placement of cortical bone fragments with attached periosteum in a culture dish. Various cell surface antibodies have been employed over the years to characterize periosteum derived progenitor cells, but the most consistent minimal criteria was recommended by the International Society for Cellular Therapy. Confirmation of the multipotent status of these isolated cells can be achieved by differentiation into the three basic mesodermal lineages in vitro.

Artificial periosteum in bone defect repair—A review

Periosteum is a thin membrane that encases the surfaces of most bones. It is composed of an outer fibrous layer contains longitudinally oriented cells and collagen fibers and an inner cambial layer that consists of multipotent mesenchymal stem cells (MSCs) and osteogenic progenitor cells. Periosteum has a function of regulating cell and collagen arrangement, which is important to the integrity, modelling and remodelling of bone, particularly during bone defect repair. Apart from autograft and allograft, artificial periosteum, or tissue-engineered periosteum mimicking native periosteum in structure or function, made up of small intestinal submucosa, acellular dermis, induced membrane, cell sheets, and polymeric scaffolds, and so on, has been developed to be used in bone defect repair. In this review, we classify the artificial periosteum into three approaches based on the material source, that is, native tissues, scaffold-free cell sheets and scaffold-cell composites. Mechanisms, methods and efficacy of each approach are provided. Existing obstacles and enabling technologies for future directions are also discussed.

Engineering biomimetic periosteum with \u03b2-TCP scaffolds to promote bone formation in calvarial defects of rats

BackgroundThere is a critical need for the management of large bone defects. The purpose of this study was to engineer a biomimetic periosteum and to combine this with a macroporous β-tricalcium phosphate (β-TCP) scaffold for bone tissue regeneration.MethodsRat bone marrow-derived mesenchymal stem cells (rBMSCs) were harvested and cultured in different culture media to form undifferentiated rBMSC sheets (undifferentiated medium (UM)) and osteogenic cell sheets (osteogenic medium (OM)). Simultaneously, rBMSCs were differentiated to induced endothelial-like cells (iECs), and the iECs were further cultured on a UM to form a vascularized cell sheet. At the same time, flow cytometry was used to detect the conversion rates of rBMSCs to iECs. The pre-vascularized cell sheet (iECs/UM) and the osteogenic cell sheet (OM) were stacked together to form a biomimetic periosteum with two distinct layers, which mimicked the fibrous layer and cambium layer of native periosteum. The biomimetic periostea were wrapped onto porous β-TCP scaffolds (BP/β-TCP) and implanted in the calvarial bone defects of rats. As controls, autologous periostea with β-TCP (AP/β-TCP) and β-TCP alone were implanted in the calvarial defects of rats, with a no implantation group as another control. At 2, 4, and 8 weeks post-surgery, implants were retrieved and X-ray, microcomputed tomography (micro-CT), histology, and immunohistochemistry staining analyses were performed.ResultsFlow cytometry results showed that rBMSCs were partially differentiated into iECs with a 35.1% conversion rate in terms of CD31. There were still 20.97% rBMSCs expressing CD90. Scanning electron microscopy (SEM) results indicated that cells from the wrapped cell sheet on the β-TCP scaffold apparently migrated into the pores of the β-TCP scaffold. The histology and immunohistochemistry staining results from in vivo implantation indicated that the BP/β-TCP and AP/β-TCP groups promoted the formation of blood vessels and new bone tissues in the bone defects more than the other two control groups. In addition, micro-CT showed that more new bone tissue formed in the BP/β-TCP and AP/β-TCP groups than the other groups.ConclusionsInducing rBMSCs to iECs could be a good strategy to obtain an endothelial cell source for prevascularization. Our findings indicate that the biomimetic periosteum with porous β-TCP scaffold has a similar ability to promote osteogenesis and angiogenesis in vivo compared to the autologous periosteum. This function could result from the double layers of biomimetic periosteum. The prevascularized cell sheet served a mimetic fibrous layer and the osteogenic cell sheet served a cambium layer of native periosteum. The biomimetic periosteum with a porous ceramic scaffold provides a new promising method for bone healing.

Periosteum tissue engineering in an orthotopic invivo platform.

The periosteum plays a critical role in bone homeostasis and regeneration. It contains a vascular component that provides vital blood supply to the cortical bone and an osteogenic niche that acts as a source of bone-forming cells. Periosteal grafts have shown promise in the regeneration of critical size defects, however their limited availability restricts their widespread clinical application. Only a small number of tissue-engineered periosteum constructs (TEPCs) have been reported in the literature. A current challenge in the development of appropriate TEPCs is a lack of pre-clinical models in which they can reliably be evaluated. In this study, we present a novel periosteum tissue engineering concept utilizing a multiphasic scaffold design in combination with different human cell types for periosteal regeneration in an orthotopic invivo platform. Human endothelial and bone marrow mesenchymal stem cells (BM-MSCs) were used to mirror both the vascular and osteogenic niche respectively. Immunohistochemistry showed that the BM-MSCs maintained their undifferentiated phenotype. The human endothelial cells developed into mature vessels and connected to host vasculature. The addition of an invitro engineered endothelial network increased vascularization in comparison to cell-free constructs. Altogether, the results showed that the human TEPC (hTEPC) successfully recapitulated the osteogenic and vascular niche of native periosteum, and that the presented orthotopic xenograft model provides a suitable invivo environment for evaluating scaffold-based tissue engineering concepts exploiting human cells.

Resting and injury-induced inflamed periosteum contain multiple macrophage subsets that are located at sites of bone growth and regeneration.

Better understanding of bone growth and regeneration mechanisms within periosteal tissues will improve understanding of bone physiology and pathology. Macrophage contributions to bone biology and repair have been established but specific investigation of periosteal macrophages has not been undertaken. We used an immunohistochemistry approach to characterize macrophages in growing murine bone and within activated periosteum induced in a mouse model of bone injury. Osteal tissue macrophages (osteomacs) and resident macrophages were distributed throughout resting periosteum. In tissues collected from 4-week-old mice, osteomacs were observed intimately associated with sites of periosteal diaphyseal and metaphyseal bone dynamics associated with normal growth. This included F4/80+Mac-2-/low osteomac association with extended tracks of bone formation (modeling) on diphyseal periosteal surfaces. Although this recapitulated endosteal osteomac characteristics, there was subtle variance in the morphology and spatial organization of periosteal modeling-associated osteomacs, which likely reflects the greater structural complexity of periosteum. Osteomacs, resident macrophages and inflammatory macrophages (F4/80+Mac-2hi) were associated with the complex bone dynamics occurring within the periosteum at the metaphyseal corticalization zone. These three macrophage subsets were also present within activated native periosteum after bone injury across a 9-day time course that spanned the inflammatory through remodeling bone healing phases. This included osteomac association with foci of endochondral ossification within the activated native periosteum. These observations confirm that osteomacs are key components of both osteal tissues, in spite of salient differences between endosteal and periosteal structure and that multiple macrophage subsets are involved in periosteal bone dynamics.

Translating Periosteum's Regenerative Power: Insights From Quantitative Analysis of Tissue Genesis With a Periosteum Substitute Implant.

In the past 2 centuries, the periosteum, a niche for stem cells and super-smart biological material, has been used empirically in surgery to repair tissues as diverse as trachea and bone. In the past 25 years, the number of articles indexed in PubMed for the keywords "periosteum and tissue engineering" and "periosteum and regenerative medicine" has burgeoned. Yet the biggest limitation to the prescriptive use of periosteum is lack of easy access, giving impetus to the development of periosteum substitutes. Recent studies have opened up the possibility to bank periosteal tissues (e.g., from the femoral neck during routine resection for implantation of hip replacements). This study used an interdisciplinary, quantitative approach to assess tissue genesis in modular periosteum substitute implants, with the aim to provide translational strategies for regenerative medicine and tissue engineering.

Periosteum tissue engineering-a review.

As always, the clinical therapy of critical size bone defects caused by trauma, tumor removal surgery or congenital malformation is facing great challenges. Currently, various approaches including autograft, allograft and cell-biomaterial composite based tissue-engineering strategies have been implemented to reconstruct injured bone. However, due to damage during the transplantation processes or design negligence of the bionic scaffolds, these methods expose vulnerabilities without the assistance of periosteum, a bilayer membrane on the outer surface of the bone. Periosteum plays a significant role in bone formation and regeneration as a store for progenitor cells, a source of local growth factors and a scaffold to recruit cells and growth factors, and more and more researchers have recognized its great value in tissue engineering application. Besides direct transplantation, periosteum-derived cells can be cultured on various scaffolds for osteogenesis or chondrogenesis application due to their availability. Research studies also provide a biomimetic methodology to synthesize artificial periosteum which mimic native periosteum in structure or function. According to the studies, these tissue-engineered periostea did obviously enhance the therapeutic effects of bone graft and scaffold engineering while they could be directly used as substitutes of native periosteum. Periosteum tissue engineering, whose related research studies have provided new opportunities for the development of bone tissue engineering and therapy, has gradually become a hot spot and there are still lots to consummate. In this review, tissue-engineered periostea were classified into four kinds and discussed, which might help subsequent researchers get a more systematic view of pseudo-periosteum.

Osteogenic Differentiation Evaluation of an Engineered Extracellular Matrix Based Tissue Sheet for Potential Periosteum Replacement.

Due to the indispensable role of periosteum in bone defect healing and regeneration, a promising method to enhance osteogenesis of bone grafts by using an engineered biomimetic periosteum would be highly beneficial. The stromal microenvironment of periosteum is composed of various highly organized extracellular matrix (ECM) fibers, so an aligned natural ECM sheet, derived from the human dermal fibroblast cell sheet, may be advantageous when applied for artificial periosteum fabrication. Human mesenchymal stem cells (hMSCs) have been used to replace the osteoprogenitor cell population in native periosteum due to hMSCs' great osteogenic potential and fast in vitro expansion capacity. The objective of this work is to investigate if the natural ECM sheet and the substrate alignment can promote in vitro osteogenesis of hMSCs. The conventional cell culture substrates collagen I-coated polydimethylsiloxane (PDMS) and tissue culture plastic (TCP) were used as controls. It was found that the ECM sheet significantly increased alkaline phosphatase activity and calcium deposition. The enhanced osteogenic potential was further confirmed by increased bone-specific gene expression. The ECM sheet can bind significantly higher amounts of growth factors including ANG-1, TGF-β1, bFGF, and VEGF, as well as calcium phosphate nanoparticles, which contributed to high osteogenesis of the hMSCs on ECM sheet. However, the alignment of the substrates did not show significant influence on osteogenic activity and growth factor binding. These results demonstrated the great potential of hMSC-seeded ECM sheet as a biomimetic periosteum to improve critical sized bone regeneration.

Emulating native periosteum cell population and subsequent paracrine factor production to promote tissue engineered periosteum-mediated allograft healing

Emulating autograft healing within the context of decellularized bone allografts has immediate clinical applications in the treatment of critical-sized bone defects. The periosteum, a thin, osteogenic tissue that surrounds bone, houses a heterogenous population of stem cells and osteoprogenitors. There is evidence that periosteum-cell derived paracrine factors, specifically vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP2), orchestrate autograft healing through host cell recruitment and subsequent tissue elaboration. In previous work, we demonstrated that the use of poly(ethylene glycol) (PEG) hydrogels as a tissue engineered (T.E.) periosteum to localize mesenchymal stem cells (MSCs) to the surface of decellularized bone enhances allograft healing and integration. Herein, we utilize a mixed population of 50:50 MSCs and osteoprogenitor cells to better mimic native periosteum cell population and paracrine factor production to further promote allograft healing. This mixed cell population was localized to the surface of decellularized allografts within degradable hydrogels and shown to expedite allograft healing. Specifically, bone callus formation and biomechanical graft–host integration are increased as compared to unmodified allografts. These results demonstrate the dual importance of periosteum-mediated paracrine factors orchestrating host cell recruitment as well as new bone formation while developing clinically translatable strategies for allograft healing and integration.

Engineering vascularized bone grafts by integrating a biomimetic periosteum and β-TCP scaffold.

Treatment of large bone defects using synthetic scaffolds remain a challenge mainly due to insufficient vascularization. This study is to engineer a vascularized bone graft by integrating a vascularized biomimetic cell-sheet-engineered periosteum (CSEP) and a biodegradable macroporous beta-tricalcium phosphate (β-TCP) scaffold. We first cultured human mesenchymal stem cells (hMSCs) to form cell sheet and human umbilical vascular endothelial cells (HUVECs) were then seeded on the undifferentiated hMSCs sheet to form vascularized cell sheet for mimicking the fibrous layer of native periosteum. A mineralized hMSCs sheet was cultured to mimic the cambium layer of native periosteum. This mineralized hMSCs sheet was first wrapped onto a cylindrical β-TCP scaffold followed by wrapping the vascularized HUVEC/hMSC sheet, thus generating a biomimetic CSEP on the β-TCP scaffold. A nonperiosteum structural cell sheets-covered β-TCP and plain β-TCP were used as controls. In vitro studies indicate that the undifferentiated hMSCs sheet facilitated HUVECs to form rich capillary-like networks. In vivo studies indicate that the biomimetic CSEP enhanced angiogenesis and functional anastomosis between the in vitro preformed human capillary networks and the mouse host vasculature. MicroCT analysis and osteocalcin staining show that the biomimetic CSEP/β-TCP graft formed more bone matrix compared to the other groups. These results suggest that the CSEP that mimics the cellular components and spatial configuration of periosteum plays a critical role in vascularization and osteogenesis. Our studies suggest that a biomimetic periosteum-covered β-TCP graft is a promising approach for bone regeneration.

Dissection in the subgaleal and subperiosteal plane: Implications on scalp wound healing

Craniofacial reconstruction often involves the use of dissection in the subperiosteal or subgaleal plane to access the cranial vault and facial skeleton. Clinically, physical changes to the periosteal layer and underlying cortex were observed in the re-operative field. This article compares aspects of wound healing, structural integrity of the progenitor periosteal layer, and underlying bony changes when elevating a subgaleal or subperiosteal flap in a Lewis rat calvarial model. Cranial dissection in the subperiosteal or subgaleal plane was performed on 14 Lewis rats. En bloc resection of the calvarium and overlying soft tissue was harvested at days 0, 1, 3, 7, 14, 28, and 56. Samples underwent SEM imaging and were analysed histologically after trichrome and haematoxylin and eosin staining. One sample of native periosteum underwent cellular expansion to determine periosteal cell regenerative capability. Up to 56 days, subperiosteal dissection results in diffuse hypercellularity within the cambial layer (p < 0.001). There are irregular cortical changes at the periosteal interface and increased disorganised bone remodelling at the temporal ridges. Subgaleal dissection did not reveal any underlying bony changes, and cell counts were not significantly different from controls (p < 0.001). Subperiosteal dissection causes structural and cellular changes to the periosteum and underlying bone composition with a possible influence on its regenerative capability.

Elucidating Multiscale Periosteal Mechanobiology: A Key to Unlocking the Smart Properties and Regenerative Capacity of the Periosteum?

The periosteum, a thin, fibrous tissue layer covering most bones, resides in a dynamic, mechanically loaded environment. The periosteum also provides a niche for mesenchymal stem cells. The mechanics of periosteum vary greatly between species and anatomical locations, indicating the specialized role of periosteum as bone's bounding membrane. Furthermore, periosteum exhibits stress-state-dependent mechanical and material properties, hallmarks of a smart material. This review discusses what is known about the multiscale mechanical and material properties of the periosteum as well as their potential effect on the mechanosensitive progenitor cells within the tissue. Furthermore, this review addresses open questions and barriers to understanding periosteum's multiscale structure-function relationships. Knowledge of the smart material properties of the periosteum will maximize the translation of periosteum and substitute periosteum to regenerative medicine, facilitate the development of biomimetic tissue-engineered periosteum for use in instances where the native periosteum is lacking or damaged, and provide inspiration for a new class of smart, advanced materials.

Dimensional change of the healed periosteum on surgically created defects.

PurposeThe final goal of regenerative periodontal therapy is to restore the structure and function of the periodontium destroyed or lost due to periodontitis. However, the role of periosteum in periodontal regeneration was relatively neglected while bone repair in the skeleton occurs as a result of a significant contribution from the periosteum. The aim of this study is to understand the histological characteristics of periosteum and compare the native periosteum with the repaired periosteum after elevating flap or after surgical intervention with flap elevation.MethodsBuccal and lingual mucoperiosteal flaps were reflected to surgically create critical-size, "box-type" (4 mm width, 5 mm depth), one-wall, intrabony defects at the distal aspect of the 2nd and the mesial aspect of the 4th mandibular premolars in the right and left jaw quadrants. Animals were sacrificed after 24 weeks.ResultsThe results from this study are as follows: 1) thickness of periosteum showed difference as follows (P<0.05): control group (0.45±0.22 mm)>flap-elevation group (0.36±0.07 mm)>defect formation group (0.26±0.03 mm), 2) thickness of gingival tissue showed difference as follows (P<0.05): defect formation group (3.15±0.40 mm)>flap-elevation group (2.02±0.25 mm)>control group (1.88±0.27 mm), 3) higher cellular activity was observed in defect formation group and flap-elevation groups than control group, 4) the number of blood vessles was higher in defect formation group than control group.ConclusionsIn conclusion, prolonged operation with increased surgical trauma seems to decrease the thickness of repaired periosteum and increase the thickness of gingiva. More blood vessles and high cellular activity were observed in defect formation group.

Determination of Shear Strength of Periosteum Attached to Bone With BioGlue Surgical Adhesive

To determine the shear strength of BioGlue Surgical Adhesive (Cryolife Inc, Kennesaw, Georgia) for use in periosteal fixation in endoscopic browplasty. In a controlled design, the shear strength of periosteal attachment to native bone and that of dissected periosteum affixed to bone with BioGlue surgical adhesive was physiologically determined. Twenty-one periosteum and bone samples were harvested from 3 human cadavers. These samples were tested for maximum shear strength using an Instron Model 5500 universal materials testing machine. Native samples consisted of periosteum still attached to the bone surface, while BioGlue samples consisted of dissected periosteum reattached to the bone surface using BioGlue surgical adhesive. The maximum shear strength attained for each sample was recorded and used to determine if native samples differed from those using BioGlue surgical adhesive. The mean (SD) maximum shear strength values obtained during testing were 57.8 (31.7) kPa and 45.9 (27.4) kPa (589.4 [323.3] gram force [gf]/cm(2) and 468.0 [279.4] gf/cm(2)) for native (n=8) and BioGlue (n=9) samples, respectively. There was no statistical difference between the native and BioGlue samples (P> .05) using analysis of variance. This study demonstrates that the adhesive properties of BioGlue are similar to the strength of attachment of native periosteum to bone and supports the use of BioGlue as an alternative method of fixation for use in endoscopic brow-lifting.

Mandibular Distraction Lengthening in the Severely Hypoplastic Mandible

Distraction lengthening is a technique that was initially developed for correction of lower limb length discrepancies. It has recently been adapted to maxillofacial problems and has gained increasing popularity in this application. This report illustrates the principles involved in mandibular distraction lengthening and offers possible solutions to potentially limiting clinical problems. First, conventional technique dictates that a distinct periosteal sleeve is necessary for distraction osteogenesis to occur. However, in this case, distraction was performed through an area of scar tissue in which the native periosteum was destroyed. The ability to extend the use of the technique of distraction successfully to suboptimal clinical situations may broaden the indications for its use. Second, fixator instability is a potentially common problem in these cases because of the forces involved in distraction osteogenesis and the duration of the process. However, mechanical rigidity is essential consolidation (typically requiring twice as long as the distraction phase). Fixator instability can be successfully salvaged during the mineralization phase of bony healing through the use of an onlay corticocancellous bone "plate," which resorbs as the distraction gap gains strength. This report highlights one of the main advantages of the distraction process: the expansion of the soft-tissue matrix of the face.