Vascularized Periosteal Flaps Accelerate Osteointegration and Revascularization of Allografts in Rats.

BACKGROUND: Surgical reconstruction of large bone defects with structural bone allografts can restore bone stock but is associated with complications such as nonunion, fracture, and infection. Vascularized reconstructive techniques may provide an alternative in the repair of critical bone defects; however, no studies specifically addressing the role of vascularized periosteal flaps in stimulating bone allograft revascularization and osseointegration have been reported. QUESTIONS/PURPOSES: (1) Does a vascularized periosteal flap increase the likelihood of union at the allograft-host junction in a critical-size defect femoral model in rats? (2) Does a vascularized periosteal flap promote revascularization of a critical-size defect structural bone allograft in a rat model? (3) What type of ossification occurs in connection with a vascularized periosteal flap? METHODS: Sixty-four rats were assigned to two equal groups. In both the control and experimental groups, a 5-cm critical size femoral defect was created in the left femur and then reconstructed with a cryopreserved structural bone allograft and intramedullary nail. In the experimental group, a vascularized periosteal flap from the medial femoral condyle, with a pedicle based on the descending genicular vessels, was associated with the allograft. The 32 rats of each group were divided into subgroups of 4-week (eight rats), 6-week (eight rats), and 10-week (16 rats) followup. At the end of their assigned followup periods, the animals were euthanized and their femurs were harvested for semiquantitative and quantitative analysis using micro-CT (all followup groups), quantitative biomechanical evaluation (eight rats from each 10-week followup group), qualitative confocal microscopic, backscattered electron microscopic, and histology analysis (4-week and 6-week groups and eight rats from each 10-week followup group). When making their analyses, all the examiners were blinded to the treatment groups from which the samples came. RESULTS: There was an improvement in allograft-host bone union in the 10-week experimental group (odds ratio [OR], 19.29 [3.63-184.50], p < 0.05). In contrast to control specimens, greater bone neoformation in the allograft segment was observed in the experimental group (OR [4-week] 63.3 [39.6-87.0], p < 0.05; OR [6-week] 43.4 [20.5-66.3], p < 0.05; OR [10-week] 62.9 [40.1-85.7], p < 0.05). In our biomechanical testing, control samples were not evaluable as a result of premature breakage during the embedding and assembly processes. Therefore, experimental samples were compared with untreated contralateral femurs. No difference in torsion resistance pattern was observed between both groups. Both backscattered electron microscopy and histology showed newly formed bone tissue and osteoclast lacunae, indicating a regulated process of bone regeneration of the initial allograft in evaluated samples from the experimental group. They also showed intramembranous ossification produced by the vascularized periosteal flap in evaluated samples from the experimental group, whereas samples from the control group showed an attempted endochondral ossification in the allograft-host bone junctions. CONCLUSIONS: A vascularized periosteal flap promotes and accelerates allograft-host bone union and revascularization of cryopreserved structural bone allografts through intramembranous ossification in a preclinical rat model. CLINICAL RELEVANCE: If large-animal models substantiate the findings made here, this approach might be used in allograft reconstructions for critical defects using fibular or tibial periosteal flaps as previously described.

Vascularized Thumb Metacarpal Periosteal Flap for Scaphoid Nonunion in Adolescents: A Prospective Cohort Study of 12 Patients.

PURPOSE: To evaluate clinical and radiological outcomes after surgical treatment of scaphoid nonunion in adolescents with a vascularized thumb metacarpal periosteal pedicled flap (VTMPF). METHODS: Twelve patients younger than 18 years with scaphoid nonunion, who underwent a VTMPF procedure without bone grafting, were included for this prospective cohort study, at a mean follow-up of 10.2 months. Patients were operated on by 3 different hand surgeons at 3 hand surgery institutions. All patients received a VTMPF, but with different scaphoid internal fixation modalities, in 10 cases using 1 or 2 retrograde 2-mm headless compression screws and in 2 cases without internal fixation. RESULTS: In 11 boys and 1 girl, the mean age was 15.6 years. There were 1 type D1 nonunions (Herbert classification), 6 type D2, 2 type D3, and 2 type D4. Six patients had previously undergone an unsuccessful surgical attempt to treat their nonunion. The mean anterior bone defect was 3.5 mm in length. The patients experienced no postoperative complications. Successful consolidation was achieved in all cases, with 79% cross-sectional trabecular bridging at 12 weeks. Pain subsided after surgery and patients experienced improvements in both their Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) and Modified Mayo Wrist Score (MMWS) results. Overall, 34% and 40% gains in strength and wrist motion, relative to the contralateral normal side, were observed. CONCLUSIONS: In this study, the use of VTMPF for scaphoid nonunion in children and adolescents is associated with generally good outcomes. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Vascularized humeral periosteal flap to treat lateral humeral condyle nonunion: An anatomical study and report of two successfully-treated pediatric cases.

PURPOSE: Nonunion is a common complication of lateral condyle humeral (LCH) fractures in children. In situ fixation with a screw and bone grafting is the classically-recommended method of treatment. The purpose of this study is to analyze the feasibility of obtaining a vascularized periosteal flap obtained from the lateral humerus and based on the posterior collateral radial vessels (PCRV). Second, to report the results after the application in two pediatric cases. METHODS: Periosteal branches of PCRV were studied in ten upper limbs from fresh human cadavers. Then, two children with LCH nonunion were treated with this flap. RESULTS: The PCRV provided mean of 5.3 anterior periosteal branches (range 4-7) with a mean distance between them of 19.1 mm (range 5-29 mm) and 5.7 posterior periosteal branches (range 3-7) with a mean distance between them of 15.9 mm (range 6-33 mm. PCRV distally anastomosed to the interosseous recurrent artery and the radial recurrent artery, creating a vascular net over the lateral condyle and allowing for the design of a reverse vascularized humeral periosteal flap (VHPF). Abundant periosteal callus and rapid consolidation were achieved in both children. No bone fixation or grafting was necessary. CONCLUSIONS: VHPF might be considered a viable biological surgical option to promote bone healing in LCH nonunions in children, while avoiding the need for bone fixation and the donor morbidity associated with bone grafting.

Histological Changes in the Periosteum Following Subperiosteal Expansion in Rabbit Scalp.

PURPOSE: In intraoral bone grafting, tension-free coverage of the recipient site with periosteal flap results in optimal wound closure. Tissue expansion could be a suitable modality to obtain soft tissue in the oral cavity. The aim of this study was to assess the histology of the periosteum after subperiosteal expansion in the rabbit scalp. MATERIALS AND METHODS: In this animal study, 6 rectangular tissue expanders were placed in the skulls of 6 male white New Zealand rabbits; in 6 control rabbits, an incision was made to the periosteum but no expansion was performed. Three months after the surgeries, the rabbits were sacrificed and tissue samples were stained with hematoxylin and eosin and Masson trichrome. RESULTS: The number of osteoblasts, fibroblasts, and blood vessels and the density of collagen fibers were significantly increased in the experimental group compared with the control group (P < .001). CONCLUSIONS: Subperiosteal tissue expansion in the rabbit scalp markedly increased the histologic components of the periosteum involved in bone regeneration.

Contractile properties of periosteal arterioles in the guinea-pig tibia.

The periosteal arterioles of the compact bone may play a critical role in bone growth. To explore the contractile properties of tibial arterioles, spontaneous and nerve-evoked constrictions were compared in preparations from 3-week-old and 1-year-old guinea-pigs. Changes in arteriole diameters were measured using video microscopy. Their innervation was investigated using fluorescence immunohistochemistry. Fifty per cent and 40% of tibial arterioles from 3-week-old and 1-year-old guinea-pigs, respectively, exhibited spontaneous phasic constrictions that were inhibited by 1 µM nifedipine, 10 µM cyclopiazonic acid or 100 µM 2-APB. Nerve-evoked phasic constrictions in both age groups were largely suppressed by phentolamine (1 µM), an α-adrenoceptor antagonist, or sympathetic neurotransmitter depletion using guanethidine (10 µM) but were enhanced by spanttide (1 µM), a substance P receptor antagonist, or L-nitro arginine (L-NA; 100 µM), an inhibitor of nitric oxide synthase (NOS). Nerve-evoked constrictions in 1-year-old animals were smaller than those in younger animals but greatly enhanced by L-NA. Immunohistochemistry revealed sympathetic and substance P-positive primary afferent nerves running along the arterioles as well as endothelial NOS expression in both age groups. Spontaneous arteriolar constrictions appear to rely on both Ca2+ release from the sarcoplasmic reticulum and Ca2+ influx through L-type Ca2+ channels. Noradrenaline released from sympathetic nerves triggers arteriolar constriction, while substance P released from primary afferent nerves dilates the arterioles by releasing nitric oxide (NO), presumably from the endothelium. Thus, the enhanced endothelial NO release in adult guinea-pigs may be important to increase the blood supply to meet the increased metabolic demands during bone growth.

The periosteal microcirculation in health and disease: An update on clinical significance.

Apart from its nutritive functions, the periosteum critically affects bone regeneration via its stem/osteoprogenitor cell content. Normal healing after bone fractures, trauma-orthopedic interventions and invasive dental procedures is critically linked to the reestablishment of the periosteal microcirculation, but the reconstruction, replacement or repair of lost tissues may also be performed with autologous periosteum. Besides the initiation of cell differentiation during bone repair and remodeling processes, the periosteum together with the endosteum plays significant roles in the pathogenesis of both hormone-related and trauma-induced osteoporotic alterations in the bone metabolism. Nevertheless, the axial bones, and in particular the jawbones, and the appendicular bones display differences not only in their blood supply and fracture healing characteristics, but also in respect of the development of osteoporosis and their reactions to treatment modalities (i.e. bisphosphonates). These reactions may also be linked to the differences in periosteal microcirculatory reactions. The present overview summarizes the relevant data of microcirculatory studies focusing on the periosteal reactions in different anatomical locations together with the optimal background methodologies, study models and the most significant observations.

Vascularized fibular grafts extended with vascularized periosteum in children.

PURPOSE: The purpose of this report is to evaluate the results of extending vascularized fibular grafts (VFG) with vascularized periosteum (VPG) in bone defect reconstruction in children. METHODS: Retrospective study of 10 children, mean age at surgery was 9.8 years (range, 4-16 years). Origin of one defect was oncological (n = 5), septical (n = 2), traumatic (n = 2), or congenital (n = 1). In five cases the flap consisted of a VFG and a vascularized epiphyseal transfer (VFET) in five. Mean bone defect was 8.5 cm .Mean length of the vascularized periosteal extension was 5.5 cm (range 3.5-8) for VFET, 4.8 cm for VFG (range 3-8). Bone union was assessed with monthly radiographs. RESULTS: Radiographs showed a periosteal callus at 4 weeks in all cases. Bone union was achieved at a mean of 8.4 weeks (range 4-12). Donor site complications included two cases of flexor hallucis longus contracture, and one case of surgical wound marginal necrosis following FVG. One transient tibialis anterior weakness and one tibialis anterior contracture occurred following VFET harvest. None required surgical treatment. Mean follow-up was 28.7 months (range 7-72). CONCLUSIONS: The association of a vascularized periosteal extension with fibular flaps seems to accelerate flap to recipient bone union. © 2016 Wiley Periodicals, Inc. Microsurgery 37:410-415, 2017.

Periosteal microcirculatory reactions in a zoledronate-induced osteonecrosis model of the jaw in rats.

OBJECTIVES: Nitrogen-containing bisphosphonates induce osteonecrosis mostly in the jaw and less frequently in other bones. Because of the crucial role of periosteal perfusion in bone repair, we investigated zoledronate-induced microcirculatory reactions in the mandibular periosteum in comparison with those in the tibia in a clinically relevant model of bisphosphonate-induced medication-related osteonecrosis of the jaw (MRONJ). MATERIALS AND METHODS: Sprague-Dawley rats were treated with zoledronate (ZOL; 80 i.v. µg/kg/week over 8 weeks) or saline vehicle. The first two right mandibular molar teeth were extracted after 3 weeks. Various systemic and local (periosteal) microcirculatory inflammatory parameters were examined by intravital videomicroscopy after 9 weeks. RESULTS: Gingival healing disorders (∼100%) and MRONJ developed in 70% of ZOL-treated cases but not after saline (shown by micro-CT). ZOL induced significantly higher degrees of periosteal leukocyte rolling and adhesion in the mandibular postcapillary venules (at both extraction and intact sites) than at the tibia. Leukocyte NADPH-oxidase activity was reduced; leukocyte CD11b and plasma TNF-alpha levels were unchanged. CONCLUSION: Chronic ZOL treatment causes a distinct microcirculatory inflammatory reaction in the mandibular periosteum but not in the tibia. The local reaction in the absence of augmented systemic leukocyte inflammatory activity suggests that topically different, endothelium-specific changes may play a critical role in the pathogenesis of MRONJ. CLINICAL RELEVANCE: This model permits for the first time to explore the microvascular processes in the mandibular periosteum after chronic ZOL treatment. This approach may contribute to a better understanding of the pathomechanism and the development of strategies to counteract bisphosphonate-induced side effects.

Vascularized tibial periosteal graft in complex cases of bone nonunion in children.

Bone nonunion in the pediatric population usually occurs in the context of highly unfavorable biological conditions. Recently, the vascularized fibular periosteal flap has been reported as a very effective procedure for treating this condition. Even though a vascularized tibial periosteal graft (VTPG) was described long ago and has been successfully employed in one adult case, there has been no other report published on the use of this technique. We report on the use of VTPG, pedicled in the anterior tibial vessels, for the treatment of two complex pediatric bone nonunion case: a recalcitrant supracondylar femoral pseudarthrosis secondary to an infection in an 11-year-old girl, and a tibial nonunion secondary to a failed bone defect reconstruction in a 12-year-old girl. Rapid healing was obtained in both cases. In the light of the data presented, we consider VTPG as a valuable surgical option for the treatment of complex bone nonunions in children.

Reconstruction of Extensive Soft-Tissue Defects with Concomitant Bone Defects in the Lower Extremity with the Latissimus Dorsi-Serratus Anterior-Rib Free Flap.

BACKGROUND: The combined latissimus dorsi-serratus anterior-rib (LD-SA-rib) free flap provides a large soft-tissue flap with a vascularized bone flap through a solitary vascular pedicle in a one-stage reconstruction. METHODS: Seven LD-SA-rib free flaps were performed in seven patients to reconstruct concomitant bone and extensive soft-tissue defects in the lower extremity (tibia, five; femur, one; foot, one). The patients were all male, with an average age of 34 years (range, 20-48 years). These defects were secondary to trauma in five patients and posttraumatic osteomyelitis in two patients. RESULTS: All flaps survived and achieved bony union. The average time to bony union was 9.4 months. Bone hypertrophy of at least 20% occurred in all flaps. All patients achieved full weight-bearing ambulation without aid at an average duration of 23.7 months. Two patients developed stress fractures of the rib flap. There was no significant donor site morbidity, except for two patients who had pleural tears during harvesting of the flap. CONCLUSION: The LD-SA-rib flap provides a large soft-tissue component and a vascularized bone flap for reconstruction of composite large soft-tissue defects with concomitant bone defects of the lower extremity in a one-stage procedure.

A novel method for in vivo visualization of the microcirculation of the mandibular periosteum in rats.

OBJECTIVE: The periosteum plays an important role in bone physiology, but observation of its microcirculation is greatly limited by methodological constraints at certain anatomical locations. This study was conducted to develop a microsurgical procedure which provides access to the mandibular periosteum in rats. METHODS: Comparisons of the microcirculatory characteristics with those of the tibial periosteum were performed to confirm the functional integrity of the microvasculature. The mandibular periosteum was reached between the facial muscles and the anterior surface of the superficial masseter muscle at the external surface of the mandibular corpus; the tibial periosteum was prepared by dissecting the covering muscles at the anteromedial surface. Intravital fluorescence microscopy was used to assess the leukocyte-endothelial interactions and the RBCV in the tibial and mandibular periosteum. Both structures were also visualized through OPS and fluorescence CLSM. RESULTS: The microcirculatory variables in the mandibular periosteum proved similar to those in the tibia, indicating that no microcirculatory failure resulted from the exposure technique. CONCLUSION: This novel surgical approach provides simple access to the mandibular periosteum of the rat, offering an excellent opportunity for investigations of microcirculatory manifestations of dentoalveolar and maxillofacial diseases.

Effects of a new piezoelectric device on periosteal microcirculation after subperiosteal preparation.

INTRODUCTION: Subperiosteal preparation using a periosteal elevator leads to disturbances of local periosteal microcirculation. Soft-tissue damage can usually be considerably reduced using piezoelectric technology. For this reason, we investigated the effects of a novel piezoelectric device on local periosteal microcirculation and compared this approach with the conventional preparation of the periosteum using a periosteal elevator. MATERIAL AND METHODS: A total of 20 Lewis rats were randomly assigned to one of two groups. Subperiosteal preparation was performed using either a piezoelectric device or a periosteal elevator. Intravital microscopy was performed immediately after the procedure as well as three and eight days postoperatively. Statistical analysis of microcirculatory parameters was performed offline using analysis of variance (ANOVA) on ranks (p<0.05). RESULTS: At all time points investigated, intravital microscopy demonstrated significantly higher levels of periosteal perfusion in the group of rats that underwent piezosurgery than in the group of rats that underwent treatment with a periosteal elevator. CONCLUSION: The use of a piezoelectric device for subperiosteal preparation is associated with better periosteal microcirculation than the use of a conventional periosteal elevator. As a result, piezoelectric devices can be expected to have a positive effect on bone metabolism.

Free vascularized medial femoral condyle periosteal flaps in the ankle and foot region: A narrative review.

OBJECTIVES: The objective of this study was to determine the role and reliability of the free medial femoral condyle (MFC) flap (MFCF) in demanding foot and ankle reconstruction procedures. MATERIALS AND METHODS: A search of the MEDLINE, PubMed, and Embase electronic databases was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines between January 2008 and September 2023. Articles concerning free MFC bone flaps for reconstruction of the foot and ankle regions were included. Outcomes of interest included flap failure, complications, union rate, time to union, and functional scores. RESULTS: Twenty studies involving 131 patients met the inclusion criteria. The most common clinical indications for the free MFCF were nonunion, avascular necrosis, and osteomyelitis. The most common sites of nonunion were tibiotalar arthrodesis (50%) and subtalar arthrodesis (33%). Overall, the bony union rate was 93.1%, with a mean time to union of 14.6±0.1 weeks. There were no flap failures reported. Postoperative complications were observed in 39 (29.7%) cases (e.g., delayed donor site wound healing, flap debulking, medial condyle osteonecrosis, and donor site numbness), with 21 (16%) patients requiring further operative intervention. No major donor or recipient site morbidity occurred, except for one case. CONCLUSION: Free MFCFs offer a versatile and dependable choice for cases of foot and ankle reconstruction, displaying favorable rates of bone fusion and acceptable complication rates. Existing literature indicates that MFC reconstruction in the foot and ankle is not associated with significant morbidity at the donor or recipient sites. The pooled data demonstrated a 93% success rate in achieving bone fusion in the foot and ankle region, supporting the view that it can be considered another option of treatment.

Free fibular flap with periosteal excess for mandibular reconstruction.

BACKGROUND: In microvascular transfer of fibular osteocutaneous flap for mandible reconstruction after cancer ablation, good bone union is necessary to allow timely radiation therapy after surgery. As the area of bone contact between fibula and the original mandible at the edge of the mandibular defect is small, a periosteal excess at both ends of the fibula covering the bone junction can be used to increase the chance of bone union. The purpose of this study is to investigate whether a periosteal excess surrounding both ends of the fibula flap can provide better blood supply and, therefore, ensure bone union and wound healing at 6 weeks after surgery and before radiation therapy initiation. PATIENTS AND METHODS: The transfer of fibular osteocutaneous flap with periosteal excess was only applied to reconstruct segmental mandibular defects. As a consequence, only cases in which osteotomy of fibula was not performed were included in this study. A total of 34 fibular flaps without osteotomies were performed between 2000 and 2008; 17 with and 17 without the periosteal excess. The bone union was evaluated in terms of osseous callus formation using X-rays and CT three-dimensional images at 6 weeks after surgery, and results were assessed by three independent radiologists. RESULTS: There was a significant difference between reconstructions with and without the periosteal excess in terms of bone union (P = 0.022). With reference to postoperative complications, the group reconstructed without periosteal excess presented a higher number of complications, mainly consisting of partial and total flap necrosis, respectively six (35.29%) and two (11.76%) cases. In the group reconstructed with periosteal excess, no loss of the skin island has occurred. A significant difference was observed in terms of partial flap necrosis (P = 0.024), while the other complications did not reveal a statistically significant difference (P > 0.05). CONCLUSIONS: The use of a periosteal excess at both ends of the fibula flap provides better blood supply and is, therefore, able to ensure good bone healing and skin paddle survival regardless of the radiotherapy.

Ex Vivo Preservation of Ovine Periosteum Using a Perfusion Bioreactor System.

Periosteum is a highly vascularized membrane lining the surface of bones. It plays essential roles in bone repair following injury and reconstruction following invasive surgeries. To broaden the use of periosteum, including for augmenting in vitro bone engineering and/or in vivo bone repair, we have developed an ex vivo perfusion bioreactor system to maintain the cellular viability and metabolism of surgically resected periosteal flaps. Each specimen was placed in a 3D printed bioreactor connected to a peristaltic pump designed for the optimal flow rates of tissue perfusate. Nutrients and oxygen were perfused via the periosteal arteries to mimic physiological conditions. Biochemical assays and histological staining indicate component cell viability after perfusion for almost 4 weeks. Our work provides the proof-of-concept of ex vivo periosteum perfusion for long-term tissue preservation, paving the way for innovative bone engineering approaches that use autotransplanted periosteum to enhance in vivo bone repair.

Local delivery of FTY720 accelerates cranial allograft incorporation and bone formation.

Endogenous stem cell recruitment to the site of skeletal injury is key to enhanced osseous remodeling and neovascularization. To this end, this study utilized a novel bone allograft coating of poly(lactic-co-glycolic acid) (PLAGA) to sustain the release of FTY720, a selective agonist for sphingosine 1-phosphate (S1P) receptors, from calvarial allografts. Uncoated allografts, vehicle-coated, low dose FTY720 in PLAGA (1:200 w:w) and high dose FTY720 in PLAGA (1:40) were implanted into critical size calvarial bone defects. The ability of local FTY720 delivery to promote angiogenesis, maximize osteoinductivity and improve allograft incorporation by recruitment of bone progenitor cells from surrounding soft tissues and microcirculation was evaluated. FTY720 bioactivity after encapsulation and release was confirmed with sphingosine kinase 2 assays. HPLC-MS quantified about 50% loaded FTY720 release of the total encapsulated drug (4.5 µg) after 5 days. Following 2 weeks of defect healing, FTY720 delivery led to statistically significant increases in bone volumes compared to controls, with total bone volume increases for uncoated, coated, low FTY720 and high FTY720 of 5.98, 3.38, 7.2 and 8.9 mm(3), respectively. The rate and extent of enhanced bone growth persisted through week 4 but, by week 8, increases in bone formation in FTY720 groups were no longer statistically significant. However, micro-computed tomography (microCT) of contrast enhanced vascular ingrowth (MICROFIL®) and histological analysis showed enhanced integration as well as directed bone growth in both high and low dose FTY720 groups compared to controls.

Limb ischemia-reperfusion differentially affects the periosteal and synovial microcirculation.

BACKGROUND: Joints are privileged compartments that enjoy increased protection against the inflammatory reactions affecting the extremities. We hypothesized that the functional characteristics of the microvasculature would contribute to the differential defensive potential of the synovial membrane. METHODS: We investigated the synovial microcirculatory reactions and compared them with those of the tibial periosteum in response to 60 min of total limb ischemia, followed by 180 min of ischemia-reperfusion (IR) in rats. Carrageenan/kaolin-induced knee monoarthritis, a neutrophil-driven synovial inflammation model, served as the positive control. RESULTS: IR brought about a significant reduction in red blood cell velocity in the capillaries and increases in rolling and adherence of the neutrophil leukocytes in the postcapillary venules (intravital microscopy), in adhesion molecule expression (intercellular adhesion molecule-1 immunohistochemistry) and in xanthine oxidoreductase activity in the periosteum. These changes were also pronounced in carrageenan/kaolin-induced monoarthritis but were almost completely absent in the synovium after the IR challenge. Most importantly, even after IR and in carrageenan/kaolin monoarthritis, the synovial microcirculation was characterized by significantly greater red blood cell velocities than that in the periosteum under resting conditions. CONCLUSIONS: The ischemic duration, which significantly affected the functional integrity of the periosteal microcirculation, did not bring about a marked deterioration in that of the synovial membrane, suggesting that the synovial microcirculation is less endangered to the consequences of short-term tourniquet exposure than the periosteum. The greater microcirculatory red blood cell velocities and lower IR-induced endothelial expression of intercellular adhesion molecule-1 in the synovial membrane might explain the greater resistance of this compartment to the inflammatory consequences of IR.

Transplantation of Cbfa1-overexpressing adipose stem cells together with vascularized periosteal flaps repair segmental bone defects.

BACKGROUND: Segmental bone defect is still a challenge to orthopedic surgeons. Currently available therapies for segmental bone defects have some drawbacks. Tissue engineering using pluripotent stem cells is a new, promising method for bone repair. The present study aims to promote the effect of bone defect repair using the tissue engineered bone in combination with vascularized periosteal flaps. METHODS: The adenoviral vector carrying Cbfa1 transduced rabbit adipose-derived mesenchymal stem cells and gene modified tissue engineering bone (GMB) were constructed. Rabbits with radial defects were implanted with the GMB together with vascularized periosteum (group A); or GMB with free periosteum (group B); or GMB (group C), and scaffold (group D). The bone repair effect was evaluated at 4, 8, or 12 wk, respectively, after the operations. RESULTS: Cbfa1 proteins were strongly expressed in adipose stem cells (ADSCs) that formed a stratified network on the inner surface of the polylactic acid/ polycaprolacton (PLA/PCL) pores. Bone repair was well achieved in the rabbits treated with the Cbfa1-expressing ADSCs and vascularized flap that was markedly better than those treated with either Cbfa1-expressing ADSCs alone or with vascularized flap alone. CONCLUSIONS: Combination with implanting the Cbfa1 gene-modified tissue-engineered bone and vascularized periosteum can better repair the segmental bone defects by stimulating osteogenesis, osteoinduction, and osteoconduction than using either one of the approaches.

Differences in the structure and osteogenesis capacity of the periosteum from different parts of minipig mandibles.

PURPOSE: To compare the structural and cellular differences of the periosteum from different parts of the mandible in minipigs by use of histologic and immunohistochemical methods to confirm the areas in which periosteal osteogenesis in situ can be used to treat mandible defects. MATERIALS AND METHODS: Three minipigs were killed, and the left mandible of each was retrieved with the periosteum remaining and then fixed, decalcified, and embedded. The specimens were cut from the buccal and lingual sides of the ramus, angle, and body of the mandible and the mentum. Sections were stained with hematoxylin-eosin and antibodies for Stro-1 (stem cell marker) and vWF (endothelial cell marker). For each periosteal area, the thickness and number of positive cells for each antibody were measured and analyzed. RESULTS: The mentum and mandibular angle periostea were thicker than those of the body and ramus. In addition, there were more blood vessels in the periostea of the mentum and mandibular body than the angle and ramus. There were more Stro-1-positive cells in the ramus periosteum than the mentum, body, and angle of the mandibles. CONCLUSIONS: The structure and cell populations of the periosteum appear to be site specific. Therefore we suggest periosteal osteogenesis in situ to treat mentum and mandibular body defects. The periosteum should be preserved as much as possible to guarantee a good healing process.

Vascularized fibular periosteal graft: a new technique to enhance bone union in children.

BACKGROUND: The periosteum in children has strong osteogenic power and is quite thick, facilitating procurement. However, it has been rarely used as a vascularized flap to enhance bone union in this age range. The purpose of this study is to assess the effectiveness of a new vascularized periosteal flap harvested from the fibula for the enhancement of bone union in the pediatric age. METHODS: Thirteen vascularized fibular periosteal grafts were used in 12 children, mean age 12.6 years. Indications included the prevention of bone allograft-host junction nonunion and treatment of recalcitrant bone nonunion. In 9 instances, the periosteal flap was harvested as a free flap and in 4 as a pedicled flap. Serial radiographs and computed tomography scans were used to evaluate the progression of callus formation and bone healing. RESULTS: All flaps were successful in promoting bone healing and achieving bone union in a mean time of 2.8 months for metaphyseal junctions and 7.1 months for diaphyseal ones, except for 1 case, which initially failed due to a pedicle torsion. It was then resolved with a second vascularized fibular periosteal grafts, with complete union after 5 months. CONCLUSIONS: Transfer of a vascularized fibular periosteal flap, either pedicled or as a free flap, is an effective treatment to enhance bone union in children in biologically unfavorable scenarios. The properties of periosteal tissue in the pediatric age are unique and its use in bone union enhancement permits new reconstructive strategies in children different from those described in adults. LEVEL OF EVIDENCE: IV.