Bone Viability Research Articles

The Human Knee: Gross, Microscopic, Surgical, and Radiological Anatomy

The Human Knee: Gross, Microscopic, Surgical, and Radiological Anatomy

Reconstrução de extremidades com retalho livre de fíbula após ressecções oncológicas

INTRODUCAO: O tumor primario de ossos longos e raro, correspondendo de 0,2% a 1% dos tumores malignos. No passado, a amputacao era o tratamento padrao, ocasionando grande impacto na morbidade e na mortalidade desses pacientes. Com o avanco das tecnicas cirurgicas e o envolvimento multidisciplinar, a cirurgia conservadora dos membros tornou-se o tratamento de escolha, sendo a reconstrucao com retalho microcirurgico de fibula a mais utilizada. Este trabalho tem como objetivo apresentar a experiencia do Instituto Nacional de Câncer (INCA) nas reconstrucoes de membros com retalho microcirurgico de fibula apos resseccoes de tumores de ossos longos. METODO: Foi realizada analise retrospectiva de 7 casos de retalho livre de fibula operados no INCA, no periodo de 1997 a 2009, para reconstrucao de defeitos de extremidades apos resseccoes de tumores osseos. Foram avaliados os seguintes parâmetros: sexo, idade, diagnostico, localizacao do tumor, tipo e tamanho da resseccao, tipo e tamanho da reconstrucao, vasos utilizados para anastomose, complicacoes pos-operatorias, estado da doenca na ultima consulta, seguimento e tempo ate deambulacao. RESULTADOS: No total, 7 pacientes com media de idade de 11,8 anos (variando de 5 anos a 14 anos) foram submetidos a reconstrucao de extremidades com retalho livre de fibula, com 100% de viabilidade e consolidacao ossea. As lesoes eram localizadas em femur, tibia ou umero. O tumor mais comum foi o osteossarcoma. O tempo medio de retorno a deambulacao foi de 14,7 meses. CONCLUSOES: O uso do retalho livre de fibula e uma excelente alternativa para reconstrucao de membros, apresentando alta taxa de consolidacao ossea, deambulacao precoce, boa funcionalidade e baixa taxa de complicacoes.

The Patellar Arterial Supply via the Infrapatellar Fat Pad (of Hoffa): A Combined Anatomical and Angiographical Analysis

Even though the vascular supply of the human patella has been object of numerous studies until now, none of them has described in detail the rich arterial supply provided via the infrapatellar fat pad (of Hoffa). Therefore, we aimed to complete the knowledge about this interesting and clinically relevant topic. Five human patellae taken from voluntary body donators were studied at the Department of Applied Anatomy of the Medical University of Vienna. One was dissected under the operation microscope, a second was made translucent by Sihlers-solution, and three underwent angiography using a 3D X-ray unit. The results revealed that the patella to a considerable amount is supplied by arteries coursing through the surrounding parts of the infrapatellar fat pad. The latter were found to branch off from the medial and lateral superior and inferior genicular arteries. Within the infrapatellar fat pad, these arteries formed a dense network of anastomoses which are all contributing to the viability of the patellar bone. Due to the rich arterial supply reaching the patella via the infrapatellar fat pad, it seems advisable to preserve the fat pad during surgery of the knee in order to reduce the risk of vascular impairment of the patella.

Free Tensor Fascia Lata-Iliac Crest Osteomusculocutaneous Flap for Reconstruction of Combined Maxillectomy and Orbital Floor Defect

Reconstruction of maxillectomy with extensive orbital rim and floor excision defects is a challenging problem. The goal of reconstruction here is to provide adequate orbital support to prevent enophthalmos and diplopia as well as obturation of the palatal defect. The existing methods of the reconstruction fail to simultaneously address these 2 goals of reconstruction. A new method of reconstruction of these defects using tensor fascia lata-iliac crest flap was used in 7 cases of cancers of the maxilla, which necessitated extensive resection of the orbital floor along with the maxillectomy. The flap was raised as a muscle and bone flap in 5 cases and in 2, a skin paddle was included. The immediate and delayed outcome at 6-month follow-up was analyzed. The functional outcome with regards to the ocular position and function, palatal obturation, speech, and swallowing were recorded. The bone viability at 6 months was assessed by computed tomography scan. The flap was successful in all the 7 cases. The delayed outcome assessment showed that the orbital support was excellent with no diplopia in all the cases. The palatal defect could be covered successfully in all the cases, resulting in normal speech and swallowing. The computed tomography scan showed excellent integration of the bone. The free tensor fascia lata-iliac crest flap is a reliable and safe method of reconstruction of the orbitomaxillary defects, addressing the issues of both orbital support and palatal obturation.

Metabolic development of necrotic bone in the femoral head following resurfacing arthroplasty

Background and purpose One concern regarding resurfacing arthroplasty is the viability of the diminished femoral head and the postoperative risk of collapse, or a femoral neck fracture. 18F-fluoride positron emission tomography (F-PET) enables us to assess bone viability despite there being a covering metal component. By F-PET studies, we recently showed the absence of metabolism in the remaining part of femoral heads, 1–4 years after surgery in 11 of 46 consecutive cases. We now present the further development of bone metabolism in these 11 cases.Patients and methods 10 patients (11 chips) with previously shown loss of femoral head metabolism were evaluated by radiography and repeated F-PET scans, 3–6.5 years after surgery. The size of the area with low 18F-fluoride PET uptake in the femoral head was compared to that in earlier PET images.Results No patients had any clinical symptoms; nor was any necrotic bone area visible in plain radiographs. On F-PET scans, 2 patients showed a diminished area with low uptake, 4 were unchanged, and 5 had enlarged areas.Interpretation Bone metabolism surrounding a volume of bone with no metabolic activity changes dynamically even 5 years after surgery. The presence of bone with minor uptake of F-tracer, indicating low or no bone metabolism, with further progression in 5 of 11 cases leads us to conclude that resurfacing THA should be used restrictively.

Flow perfusion maintainsex vivobone viability: a novel model for bone biology research

Encased in lacunae, osteocytes receive nutrition and biomechanical signals through the lacunocanalicular system. We have developed a novel flow-perfusion bioreactor designed to support lacunocanalicular fluid flow. We hypothesize that ex vivo fluid flow can maintain endochondral bone viability and, ultimately, serve as a novel model to study bone biology in vitro. Sprague-Dawley rat femurs were harvested, stripped of soft tissue, loaded into a custom-designed bioreactor and perfused with osteogenic culture medium. After 14 days of flow-perfusion or static culture, the bones were harvested, fixed, decalcified, embedded, sectioned and stained with haematoxylin and eosin. Fresh long bone samples were similarly processed for comparison. Osteocyte viability and function were also evaluated, using thiazolyl blue tetrazolium bromide (MTT), fluorospectrophotometric DNA quantification, alkaline phosphatase (ALP) colorimetric assay and fluorochrome labelling of mineralizing surfaces. All samples remained free of infection throughout the study period. After 14 days of flow perfusion, histological analysis showed normal-appearing bony architecture, with 72% of lacunae being osteocyte-filled compared with 93% in freshly harvested samples and only 36% in static samples. MTT staining and assay confirmed osteocyte viability in the flow-perfusion samples as well as in fresh samples. DNA quantification demonstrated DNA to be preserved in flow-perfused samples when compared with freshly harvested samples. ALP activity in flow-perfusion explants was upregulated compared with fresh and static samples. Fluorochrome-labelled mineralizing surfaces were seen throughout the explanted flow-perfused samples. This is the first demonstration that flow perfusion provides adequate chemotransportation to explanted murine endochondal bones.

Thein vitroeffects of antibiotics on cell viability and gene expression of equine bone marrow‐derived mesenchymal stromal cells

To investigate the effects of commonly used antibiotics on cell viability and gene expression of equine bone marrow-derived mesenchymal stromal cells (MSC) in vitro. Bone marrow-derived MSC were cultured in media containing gentamicin, amikacin, penicillin, enrofloxacin or ceftiofur at concentrations of 50, 100, 200 and 500 µg/ml. The alamarBlue fluorescence assay was used to assess cell viability over 48 h. After 5 days the cells were released and lysed prior to RNA extraction and reverse transcription. RNA levels were assessed using spectrophotometry and quantitative PCR was used to analyse gene expression of COL1A2, COL5A1, TNC, TNFα, CASP3, BCl2 and TGFβR2 relative to the reference gene GAPDH. Enrofloxacin produced a significant concentration-dependent reduction in cell viability at 200 µg/ml and higher concentrations (P = 0.009). Amikacin significantly reduced cell viability at 500 µg/ml (P = 0.002). Penicillin had no effect on cell viability at the concentrations tested (P = 0.18). Gentamicin and ceftiofur showed some interaction with the assay but had no overall effect on cell viability. At 500 µg/ml gentamicin (P<0.001), amikacin (P = 0.03), enrofloxacin (P<0.001) and ceftiofur (P<0.001) caused significant reductions in RNA levels. At 50 µg/ml gentamicin (P<0.001) and amikacin (P = 0.019) reduced BCl2 expression. Enrofloxacin produced a significant increase in COL1A2 expression (P<0.001). Enrofloxacin reduced MSC viability in vitro and may require cautious use in clinical situations. Penicillin has minimal detrimental effects on MSC in vitro and its use in conjunction with MSC at implantation appears safe. Further work is needed to fully investigate the effects of gentamicin, amikacin and ceftiofur. Clinicians using local antibiotic administration should consider the potential for local toxicity as well as the need for effective concentrations of the antibiotic.

In Vivo Response of Bone Defects Filled with Pmma in an Ovine Model

The use of PMMA cement is common in arthroplasty for cemented fixation and defect filling. Concerns remain regarding effects of cement curing temperature on the viability of cancellous bone. In this study we filled surgically-created defects (mean volume 0.585±0.251 mL) in the cancellous bone of the distal femur and proximal tibia of 6 sheep with PMMA and measured temperature changes in surrounding bone whilst the cement cured, using 3 thermocouples per defect. Animals were euthanised at 3 (n=3) and 12 (n=3) weeks postoperatively and the bone-cement interface assessed histologically. Despite mean maximum temperatures of 49.3±10.2 °C (range: 40.9 °C - 82.2 °C) thermonecrosis was not a common histological feature at either timepoint. The exposure of bone to high cement temperatures in this study has not led to bone necrosis and/or tissue damage.

Caffeine inhibits the viability and osteogenic differentiation of rat bone marrow‐derived mesenchymal stromal cells

Caffeine is consumed extensively in Europe and North America. As a risk factor for osteoporosis, epidemiological studies have observed that caffeine can decrease bone mineral density, adversely affect calcium absorption and increase the risk of bone fracture. However, the exact mechanisms have not been fully investigated. Here, we examined the effects of caffeine on the viability and osteogenesis of rat bone marrow-derived mesenchymal stromal cells (rBMSCs). Cell viability, apoptosis and necrosis were quantified using thymidine incorporation and flow cytometry. Sequential gene expressions in osteogenic process were measured by real-time PCR. cAMP, alkaline phosphatase and osteocalcin were assessed by immunoassay, spectrophotometry and radioimmunoassay, respectively. Mineralization was determined by calcium deposition. After treating BMSCs with high caffeine concentrations (0.1-1mM), their viability decreased in a concentration-dependent manner. This cell death was primarily due to necrosis and, to a small extent, apoptosis. Genes and protein sequentially expressed in osteogenesis, including Cbfa1/Runx2, collagen I, alkaline phosphatase and its protein, were significantly downregulated except for osteocalcin and its protein. Moreover, caffeine inhibited calcium deposition in a concentration- and time-dependent manner, but increased intracellular cAMP in a concentration-dependent manner. By suppressing the commitment of BMSCs to the osteogenic lineage and selectively inhibiting gene expression, caffeine downregulated some important events in osteogenesis and ultimately affected bone mass.

Long-Term Survival of Composite Hemiface/Mandible/Tongue Allografts Correlates With Multilineage Chimerism Development in the Lymphoid and Myeloid Compartments of Recipients

To maximize aesthetic and functional outcomes for complex craniofacial defects, application of composite tissue allografts opens unique one-stage reconstructive option. We have assessed role of different components of the hemiface/mandible/tongue allograft on induction and maintenance of donor-specific chimerism, in correlation with allograft survival. Twenty-two composite hemiface/mandible/tongue transplantations were performed in three groups: group 1 (n=8)-isotransplantations between Lewis (LEW) rats (RT1)-served as controls. Group 2 (n=8)-allograft rejection controls-hemiface/mandible/tongue transplants performed across major histocompatibility complex (MHC) barrier between semiallogeneic LEW-Brown-Norway (RT1) donors and LEW (RT1) recipients without immunosuppression. Allografts in group 3 (n=6) received tapered cyclosporine A monotherapy. Assessments included monitoring of rejection, flow cytometry for donor-specific chimerism of major histocompatibility complex class I (RT1) antigen, immunohistochemistry for engraftment of donor-origin cells into lymphoid organs and bone marrow (BM) compartment, and histology for hemiface/mandible/tongue architecture. Isograft controls survived indefinitely; in allografts without treatment, rejection started within 5 to 7 days. Treated hemiface/mandible/tongue allotransplants survived up to 385 days, without signs of rejection or graft loss. Flap angiography confirmed intact vascularity, and computer tomography scan and histology confirmed bone viability. Donor-specific chimerism at day 125 was present for T cells (3.3% CD4/RT1, 1.1% CD8/RT1) and B cells (6.7% CD45RA/RT1). Engraftment of donor-origin cells was confirmed into BM compartment and lymphoid organs of recipients. We introduced a new multitissue model of composite hemiface/mandible/tongue allograft containing lymphoid and vascularized BM components. Long-term allograft survival correlated with development and maintenance of donor-specific chimerism in lymphoid organs and BM compartment.

La scintigraphie osseuse dans l’évaluation de la vascularisation osseuse au niveau de la main et du poignet

Diphosphonate bone scintigraphy is used since the 1970s for studying bone pathology; it is increasingly common because of increased physical activity of the population. The disphosphonate uptake in bone requires the preservation of bone vascularity and reflects osteoblastic activity; it allows studying the viability of bone. Using data from the literature and our experience, we tried to take stock of its main uses in routine emphasizing the study of vascular and describe its use in fractures of the scaphoid and in the study of vascularised bone transfers. If the value of scintigraphy is well known, the use made by means of pinhole collimator and the market entry of new and more sensitive detectors with better resolution could allow the side of the imaging anatomy of improving the study of the vascularisation of small bone transfers which are increasingly used, particularly at wrist and hand.

Avascular necrosis (AVN) of the proximal fragment in scaphoid nonunion: Is intravenous contrast agent necessary in MRI?

Purpose The purpose of this prospective study is to assess the diagnostic value of intravenously applied contrast agent for diagnosing osteonecrosis of the proximal fragment in scaphoid nonunion, and to compare the imaging results with intraoperative findings. Materials and methods In 88 patients (7 women, 81 men) suffering from symptomatic scaphoid nonunion, preoperative MRI was performed (coronal PD-w FSE fs, sagittal-oblique T1-w SE nonenhanced and T1-w SE fs contrast-enhanced, sagittal T2*-w GRE). MRI interpretation was based on the intensity of contrast enhancement: 0 = none, 1 = focal, 2 = diffuse. Intraoperatively, the osseous viability was scored by means of bleeding points on the osteotomy site of the proximal scaphoid fragment: 0 = absent, 1 = moderate, 2 = good. Results Intraoperatively, 17 necrotic, 29 compromised, and 42 normal proximal fragments were found. In nonenhanced MRI, bone viability was judged necrotic in 1 patient, compromised in 20 patients, and unaffected in 67 patients. Contrast-enhanced MRI revealed 14 necrotic, 21 compromised, and 53 normal proximal fragments. Judging surgical findings as the standard of reference, statistical analysis for nonenhanced MRI was: sensitivity 6.3%, specificity 100%, positive PV 100%, negative PV 82.6%, and accuracy 82.9%; statistics for contrast-enhanced MRI was: sensitivity 76.5%, specificity 98.6%, positive PV 92.9%, negative PV 94.6%, and accuracy 94.3%. Sensitivity for detecting avascular proximal fragments was significantly better ( p < 0.001) in contrast-enhanced MRI in comparison to nonenhanced MRI. Conclusion Viability of the proximal fragment in scaphoid nonunion can be significantly better assessed with the use of contrast-enhanced MRI as compared to nonenhanced MRI. Bone marrow edema is an inferior indicator of osteonecrosis. Application of intravenous gadolinium is recommended for imaging scaphoid nonunion.

Comparative investigation of viability, metabolism and osteogenic capability of tissue-engineered bone preserved in sealed osteogenic media at 37 °C and 4 °C

Preservation of tissue-engineered (TE) bone is one of the key problems needed to be solved for its clinic application and industrialization. Traditional cryopreservation has been restricted because of the damages caused by ice formation and solution. Hypothermic preservation at 4 °C has been widely used for the preservation of transplanted organ despite potential negative effects on viability of cells and tissue. 37 °C is the best temperature for maintaining cellular bioactivities. However, 37 °C also has a potential negative effect on preserved cells due to consumption of nutrients and accumulation of by-products. No studies have reported which temperature is more suitable for the preservation of TE bone constructs. The current study explored the feasibility of preservation of TE bone constructs in sealed osteogenic media at 37 °C and 4 °C. Human bone marrow stromal cells (hBMSCs) were seeded into partially demineralized bone matrix (pDBM) scaffolds and cultured for 7 days to form TE bone constructs. The constructs were preserved in sealed osteogenic media at either 37 °C or 4 °C for 5, 7, 9 and 11 days, respectively. Growth kinetics, viability, metabolism and osteogenic capability were evaluated to explore the feasibility of preservation at 37 °C and 4 °C. The constructs cultured in osteogenic media at humidified 37 °C/5%CO2 served as the positive control. The results demonstrated that all the constructs preserved at 4 °C showed negative osteogenic capability at all time points with a much lower level of growth kinetics, viability and metabolism compared to the positive control. However, the constructs preserved at 37 °C showed good osteogenic capability within 7 days with a certain level of growth kinetics, viability and metabolism, although an obvious decrease in osteogenic capability was observed in the constructs preserved at 37 °C over 9 days. These results indicate that the preservation of TE bone constructs is feasible at 37 °C within 7 days in sealed osteogenic media.

Surgical angiogenesis: a new approach to maintain osseous viability in xenotransplantation

Large segmental osseous defects are challenging clinical problems. Current reconstructive methods, using non-viable allografts, vascularized autografts or prostheses have significant rates of serious complications and failure. These include infection, stress fracture and non-union (frozen structural allogenic bone); loosening and implant failure (prosthetic replacement); limited availability, poor match of size and shape and donor site morbidity (vascularized autograft bone). In the future, microvascular transplantation of living allogenic or xenogenic bone could solve some of these issues, combining the advantages of living bone autografts (capability of primary osseous healing, remodeling, and fracture resistance) with the ability to match size and shape, provide immediate stability and avoid donor site morbidity. Xenotransplants would be particularly attractive, as they could be readily available, if long-term bone survival could be achieved without unacceptable morbidity. Here, we present a preliminary study to evaluate a new and unique method to maintain xenogenic bone circulation without need for long-term immune modulation that depends upon generation of a neo-angiogenic circulation within the transplanted bone from recipient-derived vessels. Thus, only short-term immunosuppression would be required to achieve bone survival. One hundred and forty-one hamster femora were microsurgically transplanted to rats, restoring nutrient vessel circulation with standard microvascular anastomoses. At the same time, a host-derived arteriovenous bundle (AVB) was placed within the medullary canal. Two independent variables were evaluated: use of tacrolimus/cyclophosmamid immunosuppression (IS) and patency of the implanted AVB. Rats were therefore randomized to four groups; group 1-no IS + patent AVB; group 2-no IS + ligated AVB; group 3-IS + patent AVB; group 4-IS + ligated AVB. Rats were sacrificed after 1 or 2 weeks. We evaluated bone blood flow (microsphere entrapment), neoangiogenesis (microangiography and quantification of capillary density), bone necrosis rate (osteocyte counts) and nutrient pedicle rejection (microsurgical anastomotic patency). Statistical Analysis was performed with two-way ANOVA with Bonferroni adjustment. Differences were considered significant when P < 0.05. Capillary density was significantly increased with a patent intramedullary AVB (groups 1/3) compared to groups with ligated AVBs (groups 3/4). Capillary sprouting was predominantly restricted to the endosteal layer. Most nutrient pedicles (78.7%) stayed patent in groups with IS (groups 3 and 4). Consequently, bone blood flow was significantly higher in groups 3 and 4 compared to groups 1 and 2. Similarly, a patent AV bundle improved flow in group 1 when compared to group 2. The bone necrosis rate was not influenced by the presence of patent AVBs but was significantly reduced in groups 3 and 4. Surgical angiogenesis occurs when patent arteriovenous bundles are placed in the medullary canal of xenogenic bone and leads to increased bone blood flow. Bone viability was not significantly influenced by neoangiogenesis. Although capillary sprouting was restricted to the endosteal layer in this short term study, more complete cortical revascularization might be observed in a long-term study. Such a study should further evaluate whether these new vessels supply sufficient blood flow to maintain long-term bone viability and allow remodeling.

Osteonecrosis following resurfacing arthroplasty

Background and purpose One of the main concerns regarding resurfacing arthroplasty is the viability of the remaining part of the femoral head, and the postoperative risk of a femoral neck fracture or collapse. In contrast to radiographic methods, positron emission tomography using the radiotracer [18F]-fluoride (Fluoride-PET) enables us to visualize the viability of bone in the remaining part of the head, despite the presence of the covering metal component.Patients and methods This is preliminary prospective study of 14 patients who underwent an ASR resurfacing arthroplasty. Apart from clinical and radiographic analyses, all patients were analyzed by PET scan 1 week, 4 months, and 1 year after surgery.Results 1 patient had a minor region of osteonecrosis on PET scan at 1 week and at 4 months. After 1 year, the necrosis had increased to include most of the head. 2 other patients, normal at 4 months, had developed equally large osteonecrosis at 1 year. A fourth patient had a minor osteonecrosis at 1 year. None of the patients had clinical symptoms, and the necrotic areas were not visible on plain radiographs.Conclusions We found Fluoride PET to be a sensitive and useful method for evaluation of bone metabolism at resurfacing arthroplasty. 3 of the 14 patients had developed osteonecrosis, involving most of the head at 1 year. The late onset of the phenomenon does not support the hypothesis of surgically damaged vascularity. The presence of this complication together with the lack of visibility on plain radiographs gives reason for concern.

Impact of monopolar radiofrequency energy on subchondral bone viability.

The purpose of this study was to analyze the impact of monopolar radiofrequency energy treatment on subchondral bone viability. The femoral grooves of six chinchilla bastard rabbits were exposed bilaterally to monopolar radiofrequency energy for 2, 4 and 8 s, creating a total of 36 defects. An intravital fluorescence bone-labeling technique characterized the process of subchondral bone mineralization within the 3 months following exposure to radiofrequency energy and was analyzed by widefield epifluorescence optical sectioning microscopy using an ApoTome. After 2 s of radiofrequency energy exposure, regular fluorescence staining of the subchondral bone was evident in all samples when compared to untreated areas. The depth of osteonecrosis after 4 and 8 s of radiofrequency energy treatment averaged 126 and 942 µm at 22 days (P < .05; P < .01). The 4 s treatment group showed no osteonecrosis after 44 days whereas the depth of osteonecrosis extended from 519 µm at 44 days (P < .01), to 281 µm at 66 days (P < .01) and to 133 µm at 88 days (P < .05) after 8 s of radiofrequency energy application. Though radiofrequency energy may induce transient osteonecrosis in the superficial zone of the subchondral bone, the results of this study suggest that post-arthroscopic osteonecrosis appears to be of only modest risk given the current clinical application in humans.

O149. Iliac crest-tensor fascia lata osteomyocutaneous flap for orbitomaxillary reconstruction

The existing methods of the reconstruction fails to simultaneously address two goals of reconstruction of defects after maxillectomy with extensive orbital rim and floor excision: prevent enophtalmos and diplopia and palatal obturation to allow normal speech and satisfactory swallowing. A new method of reconstruction of these defects using iliac crest – tensor facial lata (TFL) flap is proposed. The results of the cadaver dissection, use of the flap in 5 clinical cases and its superiority over the existing methods are described. Initial cadaver dissections were carried out to assess the flap and pedicle characterstics of the iliac crest – TFL flap. This flap was used in 5 cases of cancer of maxilla which necessitated extensive resection of the orbital floor along with the maxillectomy. The flap was raised as a muscle and bone flap in three cases and in two a skin paddle was included. The immediate and delayed outcome at 6 month follow up were analyzed. The functional outcome with regards to the ocular position and function, palatal obturation, speech and swallowing were recorded. The bone viability at 6 months was assessed by CT scan. All the five flaps survived. The pedicle length averaged 7 cm and direct anastamosis was possible to the neck vessels. The delayed outcome assessment showed that the orbital support was excellent with no diplopia in all the cases. The palatal defect could be obturated successfully in all the cases resulting in normal speech and swallowing. The CT scan showed excellent integration in all the cases. Primary closure of the donor site was possible with evidence of no donor site morbidity. Iliac crest – TFL flap is a reliable and safe method of reconstruction of the orbitomaxillary defects. This flap addresses the issues of both orbital support and palatal obturation very well. The flap is associated with minimal morbidity and easy to harvest. С. Айэр, М. Куриакос

Comparison of Vascularized Osteoperiosteal Femur Flaps and Nonvascularized Femur Grafts for Reconstruction of Mandibular Defects: An Experimental Study

The aim of this study was to compare the vascularized osteoperiosteal femur flaps (VFFs) and the nonvascularized femur grafts (NVFGs) for reconstruction of the mandibular defects of pigs. Eight adult domestic pigs were used. The defects created in the mandibular angle were reconstructed with VFFs in 4 pigs (group 1) and NVFGs in the other 4 pigs (group 2). All the pigs were killed after 3 months of healing. Undecalcified and decalcified sections were prepared for histomorphometric analysis and histologic examination. Radiodensitometric absorptiometry was used to assess the differences in bone mineral density between the 2 groups. The bone volume to the total measured volume, trabecular thickness, and trabecular number were significantly greater in the VFF group than in the NVFG group (P < .05). However, the trabecular separation was significantly lower in the VFF group than the NVFG group (P = .029). Although the VFF group had a greater bone mineral density value than the NVFG group, the difference was not statistically significant (P = .057). In histologic examination, the viability of bone in the VFF group, enchondral bone healing, and lamellar bone formation in the NVFG group were apparent. The results of this study suggest that NVFGs have a greater bone resorption rate than do VFFs. Furthermore, the histomorphometric results imply that reconstruction of the mandibular defects with vascularized osteoperiosteal femur flaps will provide greater strength.

Prostate cancer cells home to bone in a new in vivo model of bone metastasis

This study aimed to establish the dorsal skinfold chamber (DSC) model of prostate cancer metastasis. Metatarsals from newborn mice are engrafted into a DSC implanted a SCID mouse (5‐6 weeks old). We have demonstrated that metatarsals are rapidly vascularised by inosculation with the host vasculature by day 5‐7, with functional vessels by day 2. Vascular density was measured over a 7 day period; day 3, 455 ± 186 cm/cm2; day 5, 546 ± 305 cm/cm2 and day 7, 707 ± 370 cm/cm2. Following this fluorescently labelled prostate (PC3‐GFP) or oral (SCC4‐GFP) cancer cells (1 x 105) are injected via the heart to simulate metastatic spread. Cells initially adhere to the microvascular endothelium and/or to metatarsal matrix 5 days after injection (10 ± 7 cells/metatarsal). Bone viability has been assessed throughout the 4 week study duration and demonstrates viable tissue within the DSC. Histology of the metatarsal confirms the presence of tumour cells, viability of the metatarsal, active growth plate and new vessels formation. This model will allow homing, interactions and extravasation between the tumour and bone microenvironment to be studied in detail. Funded by Sixth European Framework Programme (PROMET).

Establishing a New Orthotopic Composite Hemiface/Calvaria Transplantation Model in Rabbits

Composite tissue allograft transplantation provides a better reconstructive option for patients who suffer from extensive craniomaxillofacial deformities. However, there is a lack of sufficient experimental data including anatomical and immunologic aspects in larger animals. The purpose of this study was to develop a new orthotopic composite hemiface/calvaria transplantation model in rabbits with which to estimate the feasibility of composite tissue allografts. A total of 36 rabbits were studied. The anatomical features were explored in six rabbits. Group I (n = 6) represented the autograft group. In the allograft control group (group II, n = 12) and the treatment group (group III, n = 12), orthotopic composite hemiface/calvaria allotransplantations were performed from Dutch to Japanese White rabbits. Recipients in the treatment group received low-dose cyclosporine A/prednisone combination therapy. Evaluation methods included clinical inspection, histologic analysis, immunohistochemistry, and radiography. The animals in the autograft group survived indefinitely. Four of six nontreated allografts were rejected within 7 to 10 days. In the treatment group, five of six recipients showed no signs of rejection up to the endpoint of the study. Only one recipient died as a result of anorexia, on day 18. The histologic outcomes were well correlated with clinical inspection. Bone biopsy specimens at posttransplant days 7 and 120 revealed viable bone. Radiologic grade at day 120 showed no significant difference between the autograft (10.67 +/- 1.03) and treatment groups (9.2 +/- 1.30). Low-dose cyclosporine A/prednisone combination therapy does not influence bone viability and healing. A new orthotopic hemiface/calvaria allotransplantation model was established successfully that allows further studies on reconstruction of extensive craniomaxillofacial defects.