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PubMed2006

Evaluation of bone healing enhancement by lyophilized bone grafts supplemented with platelet gel: a standardized methodology in patients with tibial osteotomy for genu varus.

Orthopedic practice may be adversely affected by an inadequate bone repair that might compromise the success of surgery. In recent years, new approaches have been sought to improve bone healing by accelerating the rate of new bone formation and the maturation of the matrix. There is currently great interest in procedures involving the use of platelet gel (PG) to improve tissue healing, with satisfactory results both in vitro and in maxillofacial surgery. Otherwise, to our knowledge, only a preliminary clinical study was undertaken in the orthopedic field [Kitoh et al., Bone 2004;35:892-898] and the efficacy of PG is still controversial. Our paper focuses on the effect on bone regeneration by adding PG to lyophilized bone chips used for orthopedic applications. The clinical model and the laboratory methodology were standardized. As a clinical model, we employed the first series of patients of a randomized case-control study undergoing high tibial osteotomy (HTO) for genu varus. Ten subjects were enrolled: in 5 patients lyophilized bone chips supplemented with PG were inserted during tibial osteotomy (group A); 5 patients were used as a control (group B) and lyophilized bone chips without gel were applied. Forty-five days after surgery, computed tomography scan guided biopsies of grafted areas were obtained and the bone maturation was evaluated by a standardized methodology: the osteogenic and angiogenic processes were semi-quantitatively characterized by using histomorphometry, and the mineral component of the lyophilized and host bone was analyzed by using X-ray diffraction technique with sample microfocusing and microradiography. Lyophilized bone with PG seems to accelerate the healing process, as shown by new vessel formation and deposition of newly formed bone, with no evidence of inflammatory cell infiltrate, when compared with lyophilized bone without gel. On the contrary, lyophilized bone undergo a resorption process, and a fibrous tissue often fills the spaces between chips. A histiocytic/giant-cell reaction is sometimes present. Otherwise, no differences have been found concerning microstructure. Our findings show the reliability of the methodology used to monitor early bone repair. The completion of the study and the evaluation of the ultimate clinical outcome are necessary in order to verify PG in vivo effects in orthopedic surgery.

Adult↗
PubMed1989

Electronic core level microanalyses and microcopies in multipurpose apparatus.

Using an instrument equipped with two electron guns, an electron analyzer, and a Si(Li) diode detector, we developed microanalytical techniques based on inner-shell electron excitations by incident electrons and X-rays, that is, electron energy-loss spectroscopy (EELS) in the reflection mode; electron probe microanalysis (EPMA) and X-ray appearance potential spectroscopy (XAPS); electron-induced Auger electron spectroscopy (e-AES); X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS); X-ray induced AES (XAES), X-ray fluorescence analysis (XRF), and scanning X-ray radiography (SXR). The corresponding characteristic images (including X-ray microradiography and X-ray photoelectron microscopy) were obtained in the scanning mode. The principle of the apparatus is described. Each spectroscopy and microscopy is illustrated by an example. Their performance and limits are discussed.

Electron Probe Microanalysis↗
PubMed2003

Structural peculiarities of the tubercles in the skin of the turbot, Scophthalmus maximus (L., 1758) (Osteichthyes, Pleuronectiformes, Scophthalmidae).

The structure of the bony tubercles of the turbot, Scophthalmus maximus (L., 1758), was examined using ground sections, microradiography, SEM, and TEM. The tubercles are small, isolated, mineralized conical plates randomly distributed in the eyed side of the body. They are composed of three layers: the outer limiting layer, the external layer, and the basal plate, which make up the thin and flat elasmoid scales of Teleostei. The main difference between regular elasmoid scales and bony tubercles lies in the organization and the growth of the basal plate. Indeed, the conical shape of the tubercle is the result of a prominent thickening of the central part of the basal plate where the collagen matrix is organized in a complicated three-dimensional network. Densely packed thick collagen fibrils form superimposed plies organized in a plywood-like structure that resembles that of the elasmoid scales but it is criss-crossed by numerous vertical sheets of thin collagen fibrils. The tubercles originate from thin and flat plates located in the skin of larvae and juveniles, whose structure is that of regular-developing elasmoid scales. Thus, the tubercles of Scophthalmus maximus could be considered as modified elasmoid scales rather than bony structures. They might be the result of specific arrangements related to the general trend of reduction of the dermal skeleton in the teleostean lineage.

Age Factors↗
PubMed1987

Porous hydroxyapatite as a bone graft substitute in diaphyseal defects: a histometric study.

Porous hydroxyapatite (IP200), formed by conversion of the Poritidae porites exoskeleton, has pores averaging 230 microns and pore interconnections averaging 190 microns in diameter. In the distal radial diaphyses of 14 dogs, bilateral 7.5 X 20 mm cortical windows were created and fitted with 5 X 7.5 X 20 mm blocks of IP200 implants and iliac autografts. Both implanted and contralateral grafted radius specimens were retrieved at 3, 6, 12, 24, and 48 months. Unstained undecalcified sections were examined by microradiography and UV epi-illumination. Stained undecalcified sections were examined by light microscopy and quantitated by histometric methods. Implant specimens demonstrated good union and bone ingrowth at all time intervals. The implant specimens were composed of (mean +/- SE) 10.6% +/- 1.0% soft tissue, 51.2% +/- 1.3% bone, and 38.2% +/- 1.0% IP200. The graft specimens showed good union with little apparent ingrowth at 3 months, followed by progressive appositional closure of cancellous spaces. The graft specimens contained 21.9% +/- 0.9% bone at 3 months with increases at each time interval to 73.1% +/- 8.7% at 48 months. The volume fraction and mean width of IP200 did not change with time, confirming the absence of implant biodegradation. The volume fraction and mean width of bone remained stable in the implant but increased in the graft specimens, corresponding to graft neocortex formation. It is concluded that implants initially filled in with bone while grafts initially replaced much of their spongiosa and subsequently filled in with bone. Histometry of untreated defects and measurement of mechanical properties are suggested for further study.

Animals↗
PubMed1990

Internal remodeling of periosteal new bone during fracture healing.

A closed fracture model of the rat tibia was employed to study internal remodeling of periosteal new bone during fracture repair. Static histomorphometric parameters of osteoid surface (or perimeter) and eroded surface (resorption surface) were used as indicators of appositional bone formation and resorption of bone trabeculae, respectively. Intracortical remodeling at the fracture site was evaluated using quantitative tetracycline histology and microradiography. The extents of osteoid and eroded bone surfaces did not differ significantly in the periosteal woven new bone in the early phases of fracture healing. Later on, the periosteal new bone had significantly more osteoid surface than eroded surface (p less than 0.001). The number of osteoclasts also decreased significantly over time during fracture healing (p = 0.028). Cortical bone showed a continuous increase of porosity (p less than 0.01) between 1 and 6 weeks after fracture. These results suggest that there is a time-related change in the balance of periosteal bone formation and resorption during the progress of fracture repair. We hypothesize that this change was related to the restoration of bony continuity. Further studies are, however, needed to indicate the histomorphometric features of periosteal new bone in fracture nonunions.

Animals↗
PubMed2006

Density and structural changes in the bone of growing rats after weekly alendronate administration with and without a methotrexate challenge.

Alendronate (ALN) and other bisphosphonates have been used successfully in pediatric patients with osteopenia secondary to connective tissue diseases. Loss of growth in height has not been reported, but concerns remain regarding the effect of these potent antiresorptive agents when used in children and adolescents. High-dose methotrexate (MTX) and other chemotherapy drugs have been implicated in osteoporosis and a high fracture incidence in survivors of childhood cancers and are also associated with osteopenia in adult animals. The effect of high dose MTX on bone density during rapid skeletal growth, however, has not been widely studied, nor has the potentially therapeutic effect of bisphosphonates in this setting. We examined the effects of ALN and MTX administration, alone and in combination, on bone density, morphology, mechanical strength, and longitudinal growth in normal growing rats. Sprague-Dawley rats were given ALN once weekly (0.3 mg/kg) from 5 to 11 weeks of age, with and without a course of methotrexate (MTX) given daily in weeks 1 and 3 (0.75 mg/kg/day). Twenty-four animals were randomly divided into four groups: Control (vehicle), ALN alone, ALN + MTX, and MTX alone. After 6 weeks, the femora, tibiae, and lumbar spine were studied by dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, mechanical strength testing, microradiography, light microscopy, and by determination of ash weights and bone lengths. ALN treatment increased bone mineral density (BMD) by 23% to 68%. The largest increases in the femur occurred in the distal third where endochondral bone growth was greatest and included large increases in trabecular bone and total cross-sectional area. ALN + MTX produced similar effects to ALN alone. MTX only reduced BMD by 8% in the vertebrae, but not significantly at other sites. MTX also led to femoral length reductions of 2.9%. The small reductions in BMD due to MTX were overwhelmed by the increases due to ALN, whereas the length loss was unaffected. Transverse density banding corresponding to weekly ALN administrations were clearly evident radiographically throughout the growing skeleton, likely due to decreased resorption and possibly increased mineralization in the bands. ALN or ALN + MTX treatment also led to increases in mechanical strength in the femora. Although MTX administration during growth leads to some BMD reduction, ALN given with MTX eliminates this reduction and in fact bone density and strength increase above control levels.

Alendronate↗
PubMed1987

Dental pulp exposed to the CO2 laser beam.

Traumatic inflammation due to application of CO2 laser beam on teeth (dentin and pulp) of Beagle dogs and Macaca Monkeys, stimulate in dentino-pulpal tissue morphological phenomena studied after 5 days, 1, and 3 months by microscopy and microradiography. After a dentin exposure to a density of energy from 2 X 10(3) J/cm2, the first cell layers of the pulp tissue show a rarefaction and a cellular degeneration, followed by a neoformation of calcified dentin, of about 300 microns thick in 3 months, due to the excitation of odontoblasts or produced by pulpal cells functioning before. A density of energy of 10(3) J/cm2 order applied to the pulp beads to its partial necrosis, to various inflammatory aspects and to a quasi-constant regeneration by a neo-dentin bridge of 200 microns at 1 month. The analysis of cell activity seems able to be investigated from this method.

Animals↗
PubMed2005

Effects of breathing and cardiac motion on spatial resolution in the microscopic imaging of rodents.

One can acquire high-resolution pulmonary and cardiac images in live rodents with MR microscopy by synchronizing the image acquisition to the breathing cycle across multiple breaths, and gating to the cardiac cycle. The precision with which one can synchronize image acquisition to the motion defines the ultimate resolution limit that can be attained in such studies. The present work was performed to evaluate how reliably the pulmonary and cardiac structures return to the same position from breath to breath and beat to beat across the prolonged period required for MR microscopy. Radiopaque beads were surgically glued to the abdominal surface of the diaphragm and on the cardiac ventricles of anesthetized, mechanically ventilated rats. We evaluated the range of motion for the beads (relative to a reference vertebral bead) using digital microradiography with two specific biological gating methods: 1) ventilation synchronous acquisition, and 2) both ventilation synchronous and cardiac-gated acquisitions. The standard deviation (SD) of the displacement was < or =100 microm, which is comparable to the resolution limit for in vivo MRI imposed by signal-to-noise ratio (SNR) constraints. With careful control of motion, its impact on resolution can be limited. This work provides the first quantitative measure of the motion-imposed resolution limits for in vivo imaging.

Animals↗
PubMed1982

Evidence for the presence of osseous tissue in dogfish vertebrae.

The calcified cartilage of the dogfish vertebra has been studied by means of an undecalcified hard tissue method, including microradiography and tetracycline labelling, and electron microscopy. The transversely sectioned vertebra shows a centrum and neural and hemal arches. The mineralized area consists of a narrow but continuous band, which touches the perichondrium, and is formed by chondrocytes that participate in the mineralizaton of the surrounding matrix. The neural arches appear quite different; the upper parts contain an hypertrophied cartilage and, close to it, an inner zone formed by crescent shaped lamellar bone tissue containing osteoblasts and osteocytes. Tetracycline labelling of these two types of hard tissue reveals a globular calcification with calcospherites and Liesegang rings, at the level of the calcified cartilage, and a strong and linear label of the inner border of the osseous tissue. Transmission electron microscopy shows Type I collagen in the crescent shape area and Type II collagen in calcified cartilage area. The presence of osseous tissue in elasmobranch endoskeleton is discussed in relation to the evolution of the gnathostomes skeleton and the endocrinological control of calcium metabolism.

Animals↗
PubMed1992

Pathology of osteonecrosis of the femoral head. A review of experience at the Hospital for Joint Diseases, New York.

Pathological examination of the resected femoral heads from approximately 2000 total hip replacement operations carried out at the Hospital for Joint Diseases from 1984 to 1989 identified the presence of osteonecrosis in 345 patients (377 femoral heads). In 232 patients the osteonecrosis, referred to as "idiopathic," had occurred in the absence of a subcapital fracture. The present paper describes the pathology of the necrotic lesions in these 232 patients. The use of undecalcified sections and microradiography provides evidence of bone marrow calcification which, at the margin of the lesion, is sufficient to influence the radiographic features of the lesion significantly. Although a subchondral fracture is an almost constant feature of osteonecrosis when it occurs in a femoral head with a normal articular cartilage, no such fracture was found in cases in which osteonecrosis had occurred in an osteoarthritic joint.

Adult↗
PubMed1995

Bone-bonding behavior of three heat-treated silica gels implanted in mature rabbit bone.

Silica gel has been reported to induce apatite nucleation on its surface in vitro and it can act as a stimulant that induces formation of chemical apatite (Ca-P) layers on the surfaces of bioactive glass-ceramics. In this study, apatite formation in response to and the bone-bonding behavior of silica gels implanted in the tibiae of mature rabbits were studied. Implants were made from three silica gels treated at 400, 800, and 1000 degrees C, and the effects of such heat treatment on the above parameters were investigated. The silica gel was made by hydrolysis and polycondensation of tetraethoxysilane in aqueous solution containing polyethylene glycol. Rectangular implants (15 mm x 10 mm x 2 mm) of each heat-treated silica gel were implanted into both tibial bones of mature male rabbits, which were killed 4 or 8 weeks after implantation, and the tibiae containing the implants were dissected out. The bone-implant interfaces were investigated using Giemsa surface staining, contact microradiography, scanning electron microscopy-electron probe microanalysis, and X-ray diffraction. Histologically, no bonding of bone to any of the silica gels was observed at any time postimplantation. Soft tissue was observed at the bone-silica gel interface, but there were no giant foreign body or inflammatory cells. A Ca-P-rich layer was observed only on small areas of the surfaces of the silica gels treated at 400 and 800 degrees C 4 and 8 weeks after implantation. X-ray diffraction analysis confirmed the presence of hydroxyapatite in these Ca-P-rich layers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Nacre initiates biomineralization by human osteoblasts maintained in vitro.

When nacreous shell produced by the marine oyster Pinctada maxima, used as a biomaterial in oral surgery, is implanted in human bone, new bone formation occurs, resulting in a tight welding of the bone to the nacre [16]. These findings are consistent with the possibility that nacre adjacent to bone can locally stimulate osteogenic activity. To test this hypothesis, we have evaluated the effect of the simultaneous presence of bone and nacre on human osteoblasts in vitro. Nacre chips (1 mm3) were placed at approximately 1 mm distance from a similarly sized bone chip on a layer of first passage human osteoblasts. None of the chemical inducers generally required to obtain bone mineralization in vitro (in particular, beta-glycerophosphate) was added to the cultures. Mineralized sections of the cultures were evaluated by light and electron microscopy, contact microradiography, and Laser Raman Spectroscopy. The results demonstrated that nacre has strong osteogenic effects on human osteoblasts when placed in proximity to bone in vitro. New bone formation occurred by both appositional growth on the existing bone and by the formation of mineralized nodules within the matrix adjacent to the bone explant. Electron microscopic evaluation of these sites demonstrated findings typical of those described in the course of bone formation in vivo, and no evidence of toxicity was observed. In addition, under the conditions of culture used, nacre can also promote the formation by osteoblasts of a structure with characteristics similar to nacre (e.g., lamellar organic matrix mineralized with aragonite, as demonstrated by Laser Raman Spectroscopy).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

Prenatal neuroradiology: comparative radiological investigations of the embryonal and fetal brain.

In 400 embryos and fetuses of domestic animals and men, prenatal development of the cerebral vessels and ventricles was examined by postmortem arteriography, phlebography, microradiography, and ventriculography. In the ventricular system, qualitative and quantitative changes could be demonstrated and developmental diagrams of the growing ventricular spaces and angles were elaborated. The differentiation of the aortic arches into the major cranial arteries and the complex transformations of the cerebral venous system were documented by angiography within a period of gestation of 4 weeks up to term. Intrauterine angiography was also carried out in living fetuses of cats as preliminary studies of the development of cerebrovascular malformations.

Animals↗
PubMed1977

[Biocompatibility of wood in bone tissue (author's transl)].

Alcohol-extracted and sterilised cylinders of ash- and birchwood were implanted into the tibia of rabbits. The selection criteria of these two wood species were thoroughly described. 28 implants were evaluated after 3, 5, 14 and 32 weeks using undecalcified microtome sections and ground sections employing polychromatic sequential-labelling and microradiography. In spite of a foreign-body-tissue reaction new bone is formed around the implants and within the pores of the wood as well. Both wood species therefore seem to be suitable implant materials, which were anchoraged by the bone itself. A tensile strength and elastic properties comparable to bone and simple handling would be the advantages of this material.

Animals↗
PubMed1993

The quantification of bone tissue regeneration after electromagnetic stimulation.

In this study a titanium implant, the bone harvest chamber (BHC), was used to evaluate the effect of electromagnetic stimulation on osteogenesis. The BHC was inserted with a minimum of surgical trauma in the proximal tibial metaphysis in six adult lop-eared rabbits. Bone anchorage occurred after 4 weeks. After implant incorporation bone tissue was harvested at 3-week intervals with the implant in situ without killing the animal. The regenerated bone tissue was analysed by means of microradiography and densitometry. A test group and a control group each comprised six rabbits. The test group was stimulated with a 72-Hz electromagnetic field. Bone tissue was harvested from each tibia six times during the stimulation time and twice after the stimulation had been turned off. The control group had the same harvest procedure performed from one leg. Results showed that electromagnetic stimulation can maintain constant high osteogenetic activity. After the electromagnetic stimulation was turned off the osteogenetic activity diminished rapidly and osteogenesis was significantly lower than during stimulation.

Animals↗
PubMed1986

Fixation of experimental osteotomies of the distal femur in rabbits with bone cement and cyanoacrylate.

A distal femoral osteotomy was fixed with liquid cyanoacrylate and bone cement in 25 rabbits. Follow-up was done at 1, 3, 6, 12, and 24 weeks. The distal portion of each femur was removed, fixed in alcohol, embedded in methylmethacrylate, sawed to 80 micron thickness for OTC-fluorescence study and microradiography, and cut to 5-micron sections for histological analysis. Radiological and careful microscopic (OTC labeling, microradiographic, and histological) studies showed healing of the osteotomies during the first 6 weeks after operation. However, at 12 and 24 weeks' follow-up only four of ten osteotomies had healed. According to these observations it is obvious that fixation of an osteotomy of the cancellous bone with bone cement and cyanoacrylate does not provide sufficient stability for successful healing.

Adhesiveness↗
PubMed1997

Shear and tensile strength of hydroxyapatite coating under loading conditions. An experimental study in dogs.

The shear and tensile strength of a hydroxyapatite (HA) coating on a femoral component was studied after physiological loading conditions in 8 German Shepherds. A proximal macrostructure on the stem was used to protect this region from shear stresses. Another four implantations with uncoated components were used as controls. In vitro testing of the HA layer demonstrated excellent tensile strength and stability to surface deformation. The loaded implants were tested at 6, 12, and 24 weeks. At 6 weeks the HA-coated components could easily be removed by axial loading, whereas the HA layer remained undamaged on the metal. However, pull out tests of implants older than 12 weeks showed complete debonding of the HA layer from the non-macrostructured surface due to shear forces in all cases. Debonding of the HA layer was also observed with microradiography. The macrostructured surface prevented dislodging of the component from this area at pull out test by distributing shear forces. Unlike in uncoated implants, considerable amounts of bone remained attached onto the HA macrostructure when the surrounding femur was pulled out. Shear forces cause debonding of the HA layer, while tensile stress affects failure within the bone. Physiological loading partially produces gaps at the interface so direct transmission of tensile forces onto the bone is lost, and the coating-metal interface becomes the weak point in the system.

Animals↗
PubMed1997

Vascular anatomy of the ovine anterior cruciate ligament. A macroscopic, histological and radiographic study.

Sheep are being extensively utilized in animal models for orthopaedic research, but the vascular anatomy of their anterior cruciate ligament (ACL) has not yet been thoroughly described. This study demonstrates the blood supply to the ACL. Vascular injection with plastogen G, lead oxide and India ink was performed in 12 back limbs of Styrian mountain sheep, and gross observations, microradiography and routine histology were done. The large vessel and the microvascular anatomy are similar to those described for humans. The middle genicular artery and the descending genicular artery contribute vessels that supply the ACL. Epiligamentous vascular plexuses give off capillaries which penetrate the ligament substance and supply numerous, longitudinally oriented intraligamentous vessels. These findings make the Styrian mountain sheep a potential animal model for biologic investigations of ACL pathology.

Animals↗