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PubMed1997

[Observations on structure of bone in human mandibular condyles with osteophyte formation].

The purpose of this study was to investigate the functional characteristics of human mandibular condyles from a morphological viewpoint. The structure of bone in the human mandibular condyles with osteophyte formation was observed macroscopically and microscopically and compared with that in the condyles which seemed to be normal. The following observations were made: 1. Generally, it was observed that remodeling seemed to occur frequently in compact bone in the joint surface area of the mandibular condyle. 2. As the distribution of lamellar bone, nonlamellar, and bundle bone in the joint surface area changes, the compact bone seems to shift down and protrude forward. In larger osteophytes, trabeculae of cancellous bone-like structure are observed. However, the basic structure of compact bone, including haversian system and the interlamellae structure remains within the trabecullae. Therefore, observation revealed histologically that this is a compact bone. The macroscopical appearance of cancellous bone-like structure seems to be a result of functional demand. 4. It was concluded that the mandibular condyles accommodate the functional loads, and adoptational changes occur constantly in a stable manner.

Adult↗
PubMed1999

Regional differences in cortical porosity in the fractured femoral neck.

Although bone mass is a contributory risk factor for intracapsular hip fracture, its distribution and porosity within the femoral neck is also important for bone strength. In femoral neck biopsies from 13 women with intracapsular hip fracture (mean +/- SEM: 75.4+/-2.1 years, OP) and 19 cadaveric samples (9 men and 10 women [control], aged 79.4+/-1.7 years), a segmental analysis was used to quantify circumferential variations in the characteristics of cortical bone haversian systems. In female control femoral necks, there was an increasing porosity gradient between the inferior (I) (7.7+/-0.6%) and superior regions (S) (16.05+/-1.8%,p < 0.005). In walking, these regions undergo compression and tension, respectively. In men, a similar trend was observed, but the differences were not significant (I: 11.1+/-1.2%; S: 14.1+/-1.7%; p = 0.133). This porosity gradient was not maintained in the fracture group (I: 10+/-1%; S: 12.65+/-1.2%). In contrast, porosity in the fracture group was greatest in the anterior cortex, being 41% higher in that quadrant than in controls (p = 0.06). The areal density of haversian canals ranged from 16.7 to 21.3 canals/mm2 with no significant differences between fractures and controls. In the control women, mean canal diameter was highest in the superior region (60+/-2.8 microm), and these canals were significantly larger than those in the inferior region (49.4+/-1.4 microm, p < 0.05). This difference was less marked in the fracture cases (I: 53.21+/-2.5 microm; S: 59.1+/-2.8 microm; p = 0.0878). Although the mean canal diameter in the anterior quadrant of the fracture cases was higher than in the control women this did not reach significance (OP/F: 59.5+/-3 microm; control/F: 52.7+/-2.6 microm; p = 0.106). However, the proportion of "giant" canals with diameters >385 microm (defined as the top 0.5% in the controls) was doubled in the anterior region of the fracture cases (OP/F: 1.28%; control/F: 0.69%; p < 0.005). Porosity is related to the square of the canal radius; therefore, such canals make a substantial contribution to cortical porosity. Previous work has shown that the elastic modulus of bone decreases approximately as the square root of porosity. Therefore, the increased porosity and the higher prevalence of "giant" canals have a markedly negative influence on the ability of the cortical shell to withstand stresses associated with a fall. The mechanisms responsible for the localized generation of "giant" haversian canals, and ultimately the "trabecularization" of the cortex, require further investigation.

Adaptation, Physiological↗
PubMed1989

[Biomechanics of the bones and skeleton. III. Microstructure].

The authors analyzed micro- and ultrastructure of Haversian system--osteon--from the aspect of mechanics--biomechanics. The evaluation takes into account biological factors and instead of mathematical formulae and calculations prefer a comparison with technical constructions, particularly for emphasizing differences or similarities. The analysis of osteon revealed that it consists of fibres, net and tubes. The orientation of tube-like lamellae is in the direction of compressive strain, whereas the resultant course of torison and bending stress may be well observed in the direction of collagen fibres. A slight assymetry of osteons suggests that they are stressed by pressure in a slightly excentric direction. In the course of stress lengthwise there is the development of extension of the Haversian canal supporting the blood flow in the capillary. In the course of stress in the osteon lengthwise there are developing pressure, torsion and bending strains. Liquid phase can, together with collagen, absorb considerable portion of kinetic energy, thereby decreasing the strain of external strengths to act on the fragile mineralized component. Without the viscous and collagen elements the mineralized component would not be able to resist the dynamic forces which develop during the stresses in the bone tissue. Identification of mechanic phenomena of osteon provides information on structural principle of the whole bones. The authors applied in their study the knowledge from the discovery of USSR No. 181 and a discovery of CSSR No. 43.

Biomechanical Phenomena↗
PubMedDate not supplied

Structure of the osseous callus formed under electric stimulation. An experimental histological study.

The study tried to evidence histologically, histometrically and mechanically the comparative qualities of the osseous callus experimentally formed in dogs and rabbits under the influence of an electric stimulation. The materials were decalcified or polished, and the collagen network and the Haversian systems analysed in the callus. The tearing strength in kg-power on the surface unity of the osseous tissue was measured using the EDZ 20 apparatus. The results indicated that the osseous tissue formed under electric stimulation had a structure and a tearing strength similar to that of controls, and that the consolidation time of fractures is reducing.

Animals↗
PubMed2001

The effect of calcitonin on osseous healing in guinea pig mandible.

Calcitonin (CT) is reported to be an effective medication for the treatment of inflammatory root resorption and to be capable of stimulating osteoblast proliferation in cell culture studies. In this study the effect of CT on the healing of osseous defects was evaluated in the mandibles of guinea pigs. After raising tissue flaps two experimental cavities were created on both sides of the corpus mandible of 33 guinea pigs. CT was applied into cavities either in hydroxypropyl methycellulose (HPMC) gel or gelatin as carrier. HPMC and gelatin alone and an empty cavity were also examined as control groups. Histopathological examinations under light microscopy were performed on weeks 1, 3, and 6. At week 1 in CT+gelatin and CT+HPMC groups, prominent osteoblastic activity was observed when compared with control groups. At week 3 the presence of woven bone in the experimental cavity areas reflected the increased osteoblastic activity in all groups. At the end of week 6 woven bone was gradually replaced by osteogenic tissue undergoing remodelization with Haversian systems in all groups. It is suggested that the osseous healing of the experimental cavity was enhanced by CT application in early stages (i.e. at week 1). However there was no significant difference of osteogenic activity between the control and CT-treated groups at the end of weeks 3 and 6.

Animals↗
PubMed1989

[The third type of fracture healing].

Based on experimental and clinical studies, it was found that when fracture was nearly reduced, the choice and device of internal or external fixation was optimal and was used rationally, and thus rigid fixation was provided at the early stage. When immediate movements of joints were possible, relatively elastic fixation under weight-bearing at the later stage was done and no influence on transmission of the load and no signs of bone resorption could be seen at fracture ends. The fracture was repaired directly by Haversian system remodeling with a little callus. It is then called the third optimal type of fracture healing which is different from either primary or secondary healing. Using this new concept to treat fractures of long bones, not only will the fracture unite rapidly and functions restore satisfactorily, but also the strength and the stiffness of the healing bone will be greater, complications including non-union and refracture etc can be decreased or avoided.

Adult↗
PubMedDate not supplied

Radiographic and histologic analyses of stress fracture in rabbit tibias.

Sequential changes in remodeling of the internal structure of the tibia caused by controlled, excessive jumping and running were studied in 20 rabbits. Vascular changes and circulatory disturbances within the cortical bone occurred before osteoclastic resorption. Degeneration and necrosis of osteocytes due to circulatory disturbances also occurred. Periosteal new bone formation, found at and after 12 days of the experiment, was a compensatory reaction to support the tibia weakened by accelerated osteoclastic resorption. Small cracks appeared at the cement line and developed through the neighboring cement line of the haversian systems. At 21 days, incomplete fracture of the tibial cortex was found in two rabbits. Complete fracture through one side of the cortex was seen in one animal at the 50th day of the experiment. In this study, however, most of the tibias did not have visible fracture lines after a period of stressful exercise. This result suggests that most tibias adapt to changes in stress requirements through proper internal remodeling so that a complete fracture does not occur.

Animals↗
PubMed1995

Parosteal osteoma of bones other than of the skull and face.

BACKGROUND: Osteoma of the skull and facial bones is not uncommon, is usually asymptomatic, and may be associated with Gardner's syndrome. Osteomas involving other bones are unusual. METHODS: The authors describe 14 cases (eight men and six women from age 21-66 years) of parosteal osteoma of bones other than of the skull and face. RESULTS: Thirteen lesions involved long bones, and one involved the clavicle. A long-standing (18 months to 31 years) mass was reported in seven patients. Symptoms of pain, a mass, or both were present in all except three patients who were asymptomatic. Lesions ranged from 2.5 to 20 cm in greatest dimension. Histologically, they blended with the cortex, did not infiltrate the medullary cavity, and consisted of dense sclerotic lamellar bone with haversian systems, similar to the architecture of normal cortical bone. There was no spindle cell proliferation. Nine patients underwent resection, four had biopsy, and one had debulking. With a follow-up of 1-23 years, no recurrence or metastasis was reported. CONCLUSIONS: Parosteal osteoma must be distinguished from parosteal osteosarcoma, a low grade malignant neoplasm. If radiographs do not identify areas of radiolucency and sections do not contain spindle cells, the diagnosis of parosteal osteoma is justified.

Adult↗
PubMed1985

A new histologic approach to the differentiation of enchondroma and chondrosarcoma of the bones. A clinicopathologic analysis of 51 cases.

Fifty-one cases of central, hyalin cartilage tumors of the long and flat bones were analyzed. Although Grade 2 and 3 chondrosarcomas could be diagnosed on the basis of cytologic features alone, low-grade chondrosarcoma could not be adequately differentiated from pure, benign enchondroma(s) by cytology alone. The tumors can be distinguished by a new histologic approach based on tissue patterns. The crucial enchondroma patterns consist of multiple nodules of hyalin cartilage separated by normal marrow in conjunction with partial to complete encompassing plates of lamellar bone that conform to the irregular shapes of the cartilage nodules. The chondrosarcomatous patterns consist of a single confluent mass of cartilage, which commonly permeates the marrow, "trapping" host lamellar bone on all sides, and which forms bands of fibrosis between the confluent peripheral cartilage lobules. Other less common patterns included cartilagenous infiltration of the Haversian systems or marrow fat and/or the development of a soft tissue mass. A central secondary chondrosarcoma is defined as one that shows the combination of both the enchondromatous and chondrosarcomatous patterns. All 18 of the pure enchondromas diagnosed by the methods proposed in this article behaved with strict benignity (i.e., without evidence of recurrence or metastasis with an average follow-up period of 7.2 years). The 33 primary and secondary chondrosarcomas diagnosed using the described patterns behaved with the predicted frequency of recurrence, metastasis, and patient demise.

Adolescent↗
PubMed1975

Temporal bone studies: findings with undecalcified sections in a 2,600-year-old Egyptian mummy.

Roentgenologic studies by polytomography of the temporal bones of a 2,600-year-old Egyptian mummy (PUM-II) revealed an increase in radiographic density throughout the left temporal bone. The superior portions of the petrous bones were removed with an electric saw for study by undecalcified techniques. For histological control, a similar specimen was removed from a cadaver immediately after autopsy. Light microscopy of sections showed excellent preservation of the Haversian systems. The vascular channels were clearly seen, and they were similar in appearance to those of the fresh specimen. The lacunae contained osteocytes with good preservation of the nucleus. Osteoid seams were identified and the osteon activity was described for the first time in an Egyptian mummy. There was a low turnover type of bone, but there was no evidence of metabolic bone disease. We postulate that the increased radiological density of the left temporal bone was due to a greater amount of resin infiltration in this bone as compared to the right. It appeared that the resin acted as a fixative preserving the bone cells and related elements.

Cell Nucleus↗
PubMed2001

Differences in osteon banding between human and nonhuman bone.

The objective of this paper is to compare patterns of osteon organization in human and nonhuman bone. A linear organization of Haversian systems in nonhuman bone, where osteons line up in rows, has been reported but has not been quantified. The present research provides a quantitative examination of this observation through a comparative analysis of the femoral midshaft from human and nonhuman bone. Femoral midshaft thin sections from 60 humans were compared to femoral midshaft sections from nine sheep and six miniature swine. The presence or absence of osteon banding was recorded and, if present, described. Results indicate that 2 out of 60 human sections and 5 out of 15 nonhuman sections exhibit osteon banding (chi2 = 9.46; p < 0.01). Further, the type of banding present in the human and nonhuman samples is easily distinguished, indicating that human and nonhuman bone can be distinguished where handing is present in this study.

Adolescent↗
PubMed1979

The extraction from the blood of phosphate compounds by canine bone.

Uptake by bone of 99mTc-labeled pyrophosphate (PPi) and ethane-1-hydroxy-1,1-diphosphonate (EHDP) involves passage through capillaries in the Haversian system, extracellular fluid space, and membrane of osteoblasts before adsorption onto available apatite surfaces. Passage through capillaries was studied by the outflow-dilution technique in a canine tibia model in mongrel dogs. 51Cr-labeled albumin (nondiffusible reference tracer), sucrose (diffusible reference tracer), PPi, and EHDP were injected into the isolated nutrient tibial artery. Blood was collected from the ipsilateral femoral vein every 15 sec for 2 min. Emax, the apparent extraction at the time of the peaks of the dilution curves, is influenced little by back diffusion; for PP, Emax (mean +/- SD) = 0.42 +/- 0.08 (N = 4); for EHDP, Emax = 0.27 +/- 0.05 (N = 10). Net extraction (apparent fractional retention by bone at 2 min) was 0.36 +/- 0.1 for PP. Emax for 85Sr chloride and 18F sodium in our laboratory is 0.69 +/- 0.11 (N = 14) and 0.70 +/- 0.008 (N = 9), respectively. Permeabilities (P) were calculated by PS = -Fs loge (1-Emax), where Fs = plasma flow and S = capillary surface; the ratio of P for EHDP to P for sucrose was 0.71 which is similar to the ratio of diffusion coefficients, 0.78. The data suggest that EHDP and probably also PPi pass through the capillaries by passive diffusion. As expected, the extraction through capillary walls for EHDP and PPi was lower than that for 85Sr and 18F because of their larger molecular size.

Animals↗
PubMed2005

Effect of microstructure on the mechanical properties of Haversian cortical bone.

The mechanical properties of cortical bone have been extensively studied at the macrostructural scale. However, knowledge of the macroscopic mechanical properties is not sufficient to predict local phenomena, such as damage or bone remodeling, both of which are dependent on local mechanical behavior. The objective of this study is to quantify the mechanical properties of cortical bone at several length scales, with emphasis on the microstructure of Haversian systems. Samples of mature bovine cortical bone, with a Haversian microstructure, were obtained from the posterior area of the mid-femoral diaphysis. A nanoindentation technique was used to measure the local Young's modulus. The distribution of the bone mineral content was obtained by backscattered electron imaging using a scanning electron microscope. A novel compression device employing microextensometry techniques was developed to quantify local strains. Digital image correlation was performed on the microstructure imaged by optical microscopy during compression tests. This study demonstrated that the local Young's modulus and strain were heterogeneous at the scale of an osteon. For both properties, the ratio between the maximum and minimum values was approximately two. The local Young's modulus and bone-mineral content were reasonably correlated (r2 = 0.75; P < 0.0001), but this was not the case for the distribution of local strains versus bone mineral content (r2 = 0.395; P < 0.0001). Hence, local strains cannot be described simply in terms of the bone mineral content, as the Haversian canal and osteonal microstructure have a major influence on these properties. In conclusion, the microstructure must be considered in evaluating the local strain and stress fields of cortical bone.

Animals↗
PubMed1990

The clinical features of osteogenesis imperfecta resulting from a non-functional carboxy terminal pro alpha 1(I) propeptide of type I procollagen and a severe deficiency of normal type I collagen in tissues.

The features of a baby with lethal perinatal osteogenesis imperfecta (OI II), owing to a frameshift mutation that resulted in the production of a truncated and functionless carboxy terminal propeptide of the pro alpha 1(I) chain of type I procollagen, were studied. The baby (OI26) was heterozygous for an insertion of a single uridine nucleotide after base pair 4088 of the prepro alpha 1(I) mRNA of type I procollagen. Only normal type I collagen was incorporated into the extracellular matrix of bone and dermis resulting in a type I collagen content of about 20% of control tissues. The baby was born at 35 weeks' gestation and died shortly afterwards. He was small and had the radiographical features most like those of OI IIB. The skeleton was poorly ossified. The ribs were discontinuously beaded and the femora were broad with multiple healed fractures of the diaphyses and metaphyses. Other long bones had broad metaphyses with overmodelled diaphyses. The calvarium contained many hundreds of wormian bones. Histological examination showed grossly deficient endochondral and intramembranous ossification. The bone was of a woven type without evidence of lamellar bone or Haversian systems and the osteoblasts did not mature into osteocytes. The cortex of the femur contained Haversian canals but they were surrounded by loose collagen fibres and a mosaic pattern of woven bone and islands of cartilage. We propose that OI IIB can be sub-classified into two groups, one with helical mutations and both normal and mutant type I collagen in the tissues, and the other with carboxy terminal propeptide mutations and a severe type I collagen deficiency, but without mutant collagen in the tissues.

Bone and Bones↗
PubMed2003

Concept and development of an orthotropic FE model of the proximal femur.

PURPOSE: In contrast to many isotropic finite-element (FE) models of the femur in literature, it was the object of our study to develop an orthotropic FE "model femur" to realistically simulate three-dimensional bone remodelling. METHODS: The three-dimensional geometry of the proximal femur was reconstructed by CT scans of a pair of cadaveric femurs at equal distances of 2mm. These three-dimensional CT models were implemented into an FE simulation tool. Well-known "density-determined" bony material properties (Young's modulus; Poisson's ratio; ultimate strength in pressure, tension and torsion; shear modulus) were assigned to each FE of the same "CT-density-characterized" volumetric group. In order to fix the principal directions of stiffness in FE areas with the same "density characterization", the cadaveric femurs were cut in 2mm slices in frontal (left femur) and sagittal plane (right femur). Each femoral slice was scanned into a computer-based image processing system. On these images, the principal directions of stiffness of cancellous and cortical bone were determined manually using the orientation of the trabecular structures and the Haversian system. Finally, these geometric data were matched with the "CT-density characterized" three-dimensional femur model. In addition, the time and density-dependent adaptive behaviour of bone remodelling was taken into account by implementation of Carter's criterion. RESULTS: In the constructed "model femur", each FE is characterized by the principal directions of the stiffness and the "CT-density-determined" material properties of cortical and cancellous bone. Thus, on the basis of anatomic data a three-dimensional FE simulation reference model of the proximal femur was realized considering orthotropic conditions of bone behaviour. CONCLUSIONS: With the orthotropic "model femur", the fundamental basis has been formed to realize realistic simulations of the dynamical processes of bone remodelling under different loading conditions or operative procedures (osteotomies, total hip replacements, etc).

Absorptiometry, Photon↗
PubMed1998

Microdiffraction studies of bone tissues using synchrotron radiation.

This is the first report on a series of studies of the crystallinity of bone tissues. The measurements were done at the microfocused diffraction beamline at ERSF (European Synchrotron Radiation Facility) as a feasibility test on various aspects on microdiffraction analysis. Beside the crystal structure, crystallite size distribution and preferential orientation were also studied, with a spatial resolution of 7 microm. The experiments were performed at the microfocus beam line 1 at European Synchrotron Radiation Facility (ESRF). The samples were longitudinal and transversal cuts from human femoral shafts. Over 65 diffraction lines from apatite structure could be identified. The results show that the bone crystallites seem to be oriented in two orthogonal directions, one parallel with the Haversian system and the other perpendicular following the lamella's curvature. Peak width analysis shows that the crystallites are about 25-40 nm along the c-axis with a width of about 10 nm. The result also shows that the peak width is somewhat larger close to the haversian canal compared with the outer region of the osteon.

Adult↗
PubMed1993

[Observations of bone and incisor dentin of rabbits injected with rhodamine-labeled albumin by confocal laser scanning microscope].

The confocal laser scanning microscope (CLSM) is the most recently developed microscope using the confocal system and laser light source. This microscope is possible to create optical sectioning images from any depth of the specimen. In this study, the incorporation of rhodamine-labeled albumin (R-ALB) into the bone and incisor dentin was observed by CLSM. Male Japanese white rabbits were given an intravenous injection of R-ALB every two days for 10 days and sacrificed 3 days after the last injection. Transverse ground section of the tibia about 80 microns thickness showed the incorporation of orange-red fluorescence labeling into the endosteal surface as well as the Haversian system of bone. Each labeling line of R-ALB was clearly visible by CLSM compared with the normal fluorescence image. Three-dimensional reconstruction of the sectioning images showed the process of the incorporation of R-ALB into the bone and the complexity of the labeled pattern. R-ALB was incorporated into the incisor dentin and showed the periodic labeling pattern. The high resolution image of the periodic labeling pattern was observed by CLSM. These results indicated that CLSM is a valuable apparatus for studying the fluorescence labeling images of hard tissues.

Albumins↗
PubMed2001

Repairing segmental bone defects with living porous ceramic cylinders: an experimental study in dog femora.

Twenty-one porous hydroxyapatite-tricalcium phosphate ceramic cylinders 1.5 cm long and 1.2 cm in diameter were swathed with fresh autogenetic periostea taken from 21 dogs and implanted in the same animals' muscles to get living ceramic bone substitutes. These substitutes contained autogenetic growth stimulators including osteoblasts and other multipotential cells. One month later, they were transferred to the segmental bone defect sites created in femoral diaphysis of the same animals. The roentgenograms showed that in time the boundaries between the cylinders and bone sections became vague. X-ray diffraction analysis indicated that the spectra of the samples tended to be similar to those of natural bones by 6 months postoperatively. Their bending strengths also increased gradually. After the cylinders were transferred from muscles to the bone defect sites, newly formed bone tissues rapidly increased and the cylinders gradually fused with the contacted bones 2 months later. By 4 and 6 months, bone tissue occupied most areas of the materials. The ratio of newly formed bone tissue had a large lead over the materials. Haversian systems were clearly observed and matured bone tissues filled the ceramic pores and connected with each other. Results suggested that culturing complexes that consist of autogenetic periostea and biomaterials, taking advantage of living organic culturing medium, should be an effective approach to get satisfactory bioactive bone substitutes. It also provides a basis for clinically repairing bone defects in bearing sites with complex bioceramics.

Animals↗