Comparison of contamination of femoral heads and pre-processed bone chips during hip revision arthroplasty

With bone impaction grafting, cancellous bone chips made from allograft femoral heads are impacted in a bone defect, which introduces an additional source of infection. The potential benefit of the use of pre-processed bone chips was investigated by comparing the bacterial contamination of bone chips prepared intraoperatively with the bacterial contamination of pre-processed bone chips at different stages in the surgical procedure. To investigate baseline contamination of the bone grafts, specimens were collected during 88 procedures before actual use or preparation of the bone chips: in 44 procedures intraoperatively prepared chips were used (Group A) and in the other 44 procedures pre-processed bone chips were used (Group B). In 64 of these procedures (32 using locally prepared bone chips and 32 using pre-processed bone chips) specimens were also collected later in the procedure to investigate contamination after use and preparation of the bone chips. In total, 8 procedures had one or more positive specimen(s) (12.5 %). Contamination rates were not significantly different between bone chips prepared at the operating theatre and pre-processed bone chips. In conclusion, there was no difference in bacterial contamination between bone chips prepared from whole femoral heads in the operating room and pre-processed bone chips, and therefore, both types of bone allografts are comparable with respect to risk of infection.     

Parallels between development of embryonic and matrix-induced endochondral bone

Endochondral bone formation can take place in the embryo, during fracture healing, or in postnatal animals after induction by implanted demineralized bone matrix. This matrix-induced bone formation recapitulates the embryonic sequence of bone formation morphologically and biochemically. The steps in bone formation in both systems include differentiation of cartilage from mesenchyme, cartilage maturation, invasion of the cartilage by blood vessels and marrow precursors, and formation of bone and bone marrow. Recently, bone inductive molecules from demineralized bone matrix have been purified, sequenced and produced as recombinant proteins. While there are similarities between bone development in the embryo and that after induction by these purified molecules, the molecules responsible for bone induction in the embryo have not yet been defined. Because of similarities between the two methods of bone formation, studies of bone induction by demineralized bone matrix may help to elucidate mechanisms of embryonic bone induction.     

Anabolic actions of PTH in the skeletons of animals

A brief historical perspective reviews studies that tested the hypotheses that PTH induces an anabolic effect in bone, and that the gain in trabecular bone was not at the expense of cortical bone. As PTH reduces the risk of fracture in humans with osteoporosis, the myths that postulated cortical bone porosity and increased bone turnover might increase fracture risk, are examined in the light of data from animals with osteonal bone. These show that PTH "braces" the bone by immediately stimulating bone formation at modeling and remodeling sites. Increased porosity is a late event, occurring close to the neutral axis of bone where detrimental effects on biomechanical strength are unlikely. PTH increases bone mass by stimulating modeling in favor of bone formation, and restructures bone geometry via more extensive remodeling. Cell and genetic events induced in bone by PTH have been studied in rats and are time- and regimen-dependent. In addition to the stimulation of gene expression for matrix proteins, early genes upregulated by once daily PTH are those associated with matrix degradation and induction of osteoclastic resorption, indicative of possible mechanisms by which PTH may increase bone turnover. Boneforming surfaces are increased due to increased numbers of newly differentiated osteoblasts and retention of older osteoblasts by inhibition of apoptosis. After stopping treatment, the number of osteoblasts is quickly reduced and bone turnover returns to that of controls, slowing both bone formation and resorption. The increased proportion of bone undergoing PTH-induced remodeling requires maturation and completion of mineralization. These responses may explain the delay in reversal of gains in bone mass and biomechanical properties for at least two turnover cycles following withdrawal in large animal models. Thus, the skeletal benefits of PTH extend beyond the active treatment phase.     

Cellular and molecular phenotypes of osteogenic cells isolated from the medullary bone of the hen in vitro

In this study, cells isolated from hen medullary bone were cultured to examine their matrix formation. Furthermore, we compared medullary bone cells with rat bone marrow cells regarding the temporal changes in osteoblast developmental markers. Medullary bone cells were positive for alkaline phosphatase (ALP) activity and formed bone nodules, apparent with Alcian blue and von Kossa staining. The intensity of these stains became stronger with the maturation of those bone nodules. In this developmental process, the expression patterns of osteoblast phenotypes of medullary bone cells differed from those of rat bone marrow cells. ALP mRNA was expressed at the maximum level in the proliferation stage and gradually decreased in medullary bone cells, but that expression showed the opposite pattern in rat bone marrow cells. Medullary bone cells strongly expressed two non-collagenous protein mRNAs from the early stages, but the expression of these mRNAs in rat bone marrow cells increased only in the later stages. These results suggest that the features of medullary bone osteoblasts differ from those of mammalian osteoblasts and are reflected in the characteristics of medullary bone in vivo.     

Imbalance of local bone metabolism in inflammatory arthritis and its reversal upon tumor necrosis factor blockade: direct analysis of bone turnover in murine arthritis

Chronic arthritis typically leads to loss of periarticular bone, which results from an imbalance between bone formation and bone resorption. Recent research has focused on the role of osteoclastogenesis and bone resorption in arthritis. Bone resorption cannot be observed isolated, however, since it is closely linked to bone formation and altered bone formation may also affect inflammatory bone loss. To simultaneously assess bone resorption and bone formation in inflammatory arthritis, we developed a histological technique that allows visualization of osteoblast function by in-situ hybridization for osteocalcin and osteoclast function by histochemistry for tartrate-resistant acid phosphatase. Paw sections from human tumor necrosis factor transgenic mice, which develop an erosive arthritis, were analyzed at three different skeletal sites: subchondral bone erosions, adjacent cortical bone channels, and endosteal regions distant from bone erosions. In subchondral bone erosions, osteoclasts were far more common than osteoblasts. In contrast, cortical bone channels underneath subchondral bone erosions showed an accumulation of osteoclasts but also of functional osteoblasts resembling a status of high bone turnover. In contrast, more distant skeletal sites showed only very low bone turnover with few scattered osteoclasts and osteoblasts. Within subchondral bone erosions, osteoclasts populated the subchondral as well as the inner wall, whereas osteoblasts were almost exclusively found along the cortical surface. Blockade of tumor necrosis factor reversed the negative balance of bone turnover, leading to a reduction of osteoclast numbers and enhanced osteoblast numbers, whereas the blockade of osteoclastogenesis by osteoprotegerin also abrogated the osteoblastic response. These data indicate that bone resorption dominates at skeletal sites close to synovial inflammatory tissue, whereas bone formation is induced at more distant sites attempting to counter-regulate bone resorption.     

Imbalance of local bone metabolism in inflammatory arthritis and its reversal upon tumor necrosis factor blockade: direct analysis of bone turnover in murine arthritis

Chronic arthritis typically leads to loss of periarticular bone, which results from an imbalance between bone formation and bone resorption. Recent research has focused on the role of osteoclastogenesis and bone resorption in arthritis. Bone resorption cannot be observed isolated, however, since it is closely linked to bone formation and altered bone formation may also affect inflammatory bone loss. To simultaneously assess bone resorption and bone formation in inflammatory arthritis, we developed a histological technique that allows visualization of osteoblast function by in-situ hybridization for osteocalcin and osteoclast function by histochemistry for tartrate-resistant acid phosphatase. Paw sections from human tumor necrosis factor transgenic mice, which develop an erosive arthritis, were analyzed at three different skeletal sites: subchondral bone erosions, adjacent cortical bone channels, and endosteal regions distant from bone erosions. In subchondral bone erosions, osteoclasts were far more common than osteoblasts. In contrast, cortical bone channels underneath subchondral bone erosions showed an accumulation of osteoclasts but also of functional osteoblasts resembling a status of high bone turnover. In contrast, more distant skeletal sites showed only very low bone turnover with few scattered osteoclasts and osteoblasts. Within subchondral bone erosions, osteoclasts populated the subchondral as well as the inner wall, whereas osteoblasts were almost exclusively found along the cortical surface. Blockade of tumor necrosis factor reversed the negative balance of bone turnover, leading to a reduction of osteoclast numbers and enhanced osteoblast numbers, whereas the blockade of osteoclastogenesis by osteoprotegerin also abrogated the osteoblastic response. These data indicate that bone resorption dominates at skeletal sites close to synovial inflammatory tissue, whereas bone formation is induced at more distant sites attempting to counter-regulate bone resorption.     

Self-maintenance of induced bone tissue]

The capacity for self-maintenance of the bone marrow osteogenic precursor cells from the skeletal bones and from the bones induced by implantation of decalcified bone matrix is compared. Transplantation in diffusion chambers is employed as the test system. Osteogenesis in the bone marrow transplants isolated from the skeletal bone lasts several months, whereas osteogenesis in the bone marrow transplants isolated from induced bone stops after the second month. Fibroblasts arising in the monolayer cultures of the skeletal bone marrow retained their osteogenic potencies after repeated passages. On the contrary, fibroblasts from the monolayer cultures of induced bone marrow lost their osteogenic capacity after the second passage. Thus, contrary to osteogenic precursors of the skeletal bone, osteogenic precursors of induced bone tissue had a very limited self-maintaining capacity after the cessation of induction.     

Effect of bone marrow cells on colony-forming stromal cells in guinea pigs and on the proliferation of their cultured descendents

In the presence of irradiated bone marrow cells the efficiency of stromal colony formation increases from 0.8 +/- 0.2 to 3.6 +/- 0.4 per 10(4) explanted bone marrow cells. The growth-stimulating activity of bone marrow cells on passaged bone marrow fibroblasts depends on growth conditions of passages to which irradiated bone marrow cells are added. The response of proliferating bone marrow fibroblasts to stimulating activity of bone marrow cells is low, while addition of bone marrow cells to fibroblast cultures stimulates their proliferation.     

骨吸收与骨形成耦联中Eph/ephrin信号转导的研究进展

破骨细胞的骨吸收活动与成骨细胞的骨形成活动相互作用调节,形成一种特殊的耦联机制,影响骨骼生长、发育及正常骨组织结构的维持．最近几年提出的Eph/ephrin双向信号转导在骨吸收与骨形成耦联中的研究越来越受到关注．从Eph/ephrin分子结构、信号转导机制及生物学意义等几方面对该理论作一阐述．     

Bone quality assessment in individuals of different age, gender and body constitution

The concept of bone quality describes the sets of the characteristics of the osseous tissue that influence bone strength. The aim was to explore the influence of anthropometric parameters and age on the parameters of the bone architecture and bone mineral properties in the lumbar vertebral bone of men and women. Vertebral bone samples underwent bone histomorphometry, bone densitometry and atomic absorption spectrometry. Men have greater values of the bone volume and thicker bone trabeculae in relation to women, which indicates that vertebral bone architecture is better preserved in men than in women. Age is the best predictor of changes that affect bone architecture and bone mineral properties. Bone mineral density value and calcium concentration are both negatively predicted by age, but positively predicted by body mass index. Such result supports the opinion that low body mass index is associated with conditions of bone deficit such are osteopenia and osteoporosis.     

Scanning electron microscopic and light microscopic observations on morphological changes of freeze-dried bone implantation in rats: comparison with fresh autogenous bone transplantation.

Bone remodelling after the implantation of freeze-dried autogenous bone in rat parietal bone was compared with fresh autogenous bone transplantation, using a scanning electron and light microscope revealed the time intervals after transplantation/implantation. The light microscope revealed the time delay of the bone remodelling in the implantation, compared with the transplantations. The scanning electron microscope showed that the differences between the two groups were in the states of bone union and bone resorption. In the fresh bone group, the newly-formed bone filled the spaces between host and the transplanted bones at 2 to 3 weeks after the transplantation: the newly-formed bone fused and melted into the transplanted bone. New bone formation was more dominant on the bone surface in the dura mater side than in the skin side. The union was almost completed at 5 weeks. In freeze-dried bone implantation, the bone union in the contact space was very poor and the implanted bone was mainly covered by the new bone, which developed from the host bone surface in the dura mater side at 2 to 3 weeks after the implantation. What is noteworthy is that bone resorbed areas showing numerous Howship's lacunae were mainly observed on the host bone surface in the vicinity of newly-formed bone. However in freeze-dried bone implantation, the bone resorption was greater on the host and implanted bone surface than that of fresh bone transplantation: the resorption of host bone was considerably larger at certain periods after freeze-dried bone implantation. The present results show that the healing process of freeze-dried bone implantation, even though autogenous bone was used, differed from that of fresh autogenous bone transplantation, and the differences are concerned not only with time sequences but also with qualitative changes. This suggests that the host would have some different responses to the freeze-dried autogenous bone from fresh materials.     

The Concentration of Manganese, Iron and Strontium in Bone of Red Fox Vulpes vulpes (L. 1758)

The aims of the study were to determine manganese (Mn), iron (Fe) and strontium (Sr) concentrations in fox bone samples from north-western Poland and to examine the relationships between the bone Mn, Fe and Sr concentrations and the sex and age of the foxes. In the studied samples of fox cartilage, cartilage with adjacent compact bone, compact bone and spongy bone, the concentrations of the analysed metals had the following descending order: Fe > Sr > Mn. The only exception was in compact bone, in which the concentrations were arranged in the order Sr > Fe > Mn. Manganese concentrations were significantly higher in cartilage, compact bone and cartilage with compact bone than in spongy bone. Iron concentrations were higher in cartilage and spongy bone compared with compact bone. Strontium concentrations were greater in compact bone than in cartilage and spongy bone. The manganese, iron and strontium concentrations in the same type of bone material in many cases correlated with each other, with the strongest correlation (r?>?0.70) between Mn and Fe in almost all types of samples. In addition, concentrations of the same metals in different bone materials were closely correlated for Mn and Fe in cartilage and cartilage with adjacent compact bone, and for Sr in compact bone and cartilage with compact bone. In the fox from NW Poland, there were no statistically significant differences in Mn, Fe and Sr in any of the types of bone material between the sexes and immature and adult foxes.     

Mechanisms of bone metastasis formation

Bone is a common metastatic site for many cancers. Tumor cells located in the bone marrow cavity disturb the natural balance (bone remodelling) established between new bone formation performed by osteoblasts and bone resorption carried out by osteoclasts. Tumor cells produce many factors including growth factors and cytokines (PTHrP, ET-1, BMPs, others...) that stimulate either ostoclast activity leading to osteolytic lesions or osteoblast activity generating osteosclerotic bone metastases. Growth factors released from resorbed bone matrix or throughout osteoblastic bone formation sustain tumor growth. Therefore, bone metastases are the site of vicious cycles wherein tumor growth and bone metabolism sustain each other.     

The mechanobiological effects of periosteal surface loads

We have developed an improved mechanobiological model of bone morphogenesis and functional adaptation that includes the influences of periosteum tension and pressure on bone formation and resorption. Previous models assumed that periosteal and endosteal bone deposition and resorption rates are governed only by the local intracortical daily stress or strain stimulus caused by cyclic loading. The new model incorporates experimental findings that pressures on periosteal surfaces can impede bone formation or induce bone resorption, whereas periosteal tensile strains perpendicular to bone surfaces can impede bone resorption or induce bone formation. We propose that these effects can produce flattened or concave bone surfaces in regions of periosteal pressure and bone ridges in regions of periosteal tension. The model was implemented with computer simulations to illustrate the role of adjacent muscles on the development of the triangular cross-sectional geometry of the rat tibia. The results suggest that intracortical stresses dictate bone size, whereas periosteal pressures may work in combination with intracortical stresses and other mechanobiological factors in the development of local bone cross-sectional shapes.     

Effects of age,sex, and heredity on measures of bone mass in baboons (Papio hamadryas)

Abstract: Bone mass and bone density were estimated in 219 pedigreed baboons (Papio hamadryas) by radiographic morphometry of the left second metacarpal. Compact bone width (total bone width – medullary canal diameter) and bone ratio (compact bone width/total bone width) decreased with increasing age squared in both sexes. The heritability of medullary canal diameter was 0.64±0.11, of compact bone width was 0.40±0.15 and of bone ratio was 0.67±0.13. The results indicate baboons are a useful model for studies of age, sex and genetic effects on bone mass.     

Effect of treadmill exercise on bone mass in female rats.

Increasing peak bone mass at skeletal maturity, minimizing bone loss during middle age and after menopause, and increasing bone mass and preventing falls in advanced age are important measures for preventing osteoporotic fractures in women. Exercise has generally been considered to have a positive influence on bone health. This paper reviews the effects of treadmill exercise on bone in young, adult, ovariectomized, and osteopenic female rats. Treadmill exercise increases cortical and cancellous bone mass of the tibia as a result of increased bone formation and decreased bone resorption in young and adult rats. The increase in lumbar bone mass seems to be more significant when long-term exercise is applied. Treadmill exercise prevents cancellous bone loss at the tibia as a result of suppressed bone resorption in ovariectomized rats, and increases bone mass of the tibia and mechanical strength of the femur, as a result of suppressed bone resorption and increased bone formation in osteopenic rats after ovariectomy. Treadmill exercise transiently decreases the serum calcium level as a result of accumulation of calcium in bone, resulting in an increase in serum 1,25-dihydroxyvitamin D(3) level and a decrease in serum parathyroid hormone level. We conclude that treadmill exercise may be useful to increase bone mass in young and adult rats, prevent bone loss in ovariectomized rats, and increase bone mass and bone strength in osteopenic rats, especially in the long bones at weight-bearing sites. Treadmill exercise may have a positive effect on the skeleton in young, and adult, ovariectomized, and osteopenic female rats.     

The development of acellularity of the vertebral bone of the Japanese medaka,Oryzias latipes (Teleostei; Cyprinidontidae)

Among vertebrates, some teleosts are unique in having bone which lacks osteocytes embedded in the matrix. The fate of cells that secrete the matrix of these acellular bones has not been investigated thoroughly. Histological and fluorescent microscopic analysis of the vertebral bone of Oryzias latipes demonstrated that acellularity is not a secondary appearance of an early cellular bone during ontogeny. Vertebral bone is devoid of cells embedded in the matrix throughout development. Cells that secrete bone matrix do not become trapped in their own secretion. Instead, they always remain as a surface layer over the outer surface of the bone. Fluorescent microscopic visualization of tetracycline injected into growing fish demonstrated that bone was only deposited by osteoblasts lining the outer surface of the bone; no deposition of bone took place on the inner surface.     

Static and dynamic finite element analyses of an idealized structural model of vertebral trabecular bone.

An idealized three-dimensional finite element model of a rodlike trabecular bone structure was developed to study its static and dynamic responses under compressive loading, considering the effects of bone marrow and apparent density. Static analysis of the model predicted hydraulic stiffening of trabecular bone due to the presence of bone marrow. The predicted power equation relating trabecular bone apparent elastic modulus to its apparent density was in good agreement with those of the reported experimental investigations. The ratio of the maximum stress in the trabecular bone tissue to its apparent stress had a high value, decreasing with increasing bone apparent density. Frequency analyses of the model predicted higher natural frequencies for the bone without marrow than those for the bone with marrow. Adding a mass relatively large compared to that of bone rendered a single-degree-of-freedom response. In this case, the resonant frequency was higher for the bone with marrow than that for the bone without marrow. The predicted vibrational measurement of apparent modulus was in good agreement with that of the static measurement, suggesting vibrational testing as a method for nondestructive measurement of trabecular bone elastic moduli.     

Evidence that failure of osteoid bone matrix resorption is caused by perturbation of osteoclast polarization

Osteoclasts resorb bone by a complex dynamic process that initially involves attachment, polarization and enzyme secretion, followed by their detachment and migration to new sites. In this study, we postulated that mineralized and osteoid bone matrix signal osteoclasts differently, resulting in the resorption of mineralized bone matrix only. We, therefore, compared the cytoplasmic distribution of cytoskeletal proteins F-actin and vinculin using confocal laser-scanning microscopy in osteoclasts cultured on mineralized and demineralized bone slices and correlated the observations with their functional activity. Our results have demonstrated significant differences in F-actin and vinculin staining patterns between osteoclasts cultured on mineralized bone matrix and those on demineralized bone matrix. In addition, the structural variations were accompanied by significant differences in bone resorbing activity between osteoclasts grown on mineralized bone matrix and those on demineralized bone matrix after 24 h of culture -- resorption only occurring in mineralized bone but not in demineralized bone. These results indicated that failure of osteoid bone resorption is caused by perturbation of osteoclast polarization. © 1998 Chapman & Hall     

微波高温灭活及自体髂骨异体骨粒复合骨水泥修复 治疗长骨骨巨细胞瘤骨缺损

目的:探讨微波高温灭活及自体髂骨、异体骨粒复合骨水泥修复骨巨细胞瘤病灶刮除后骨缺损的临床应用效果。方法:应用原位分离插入式微波天线高温灭活技术,自体髂骨、异体骨粒复合骨水泥修复21例长骨骨巨细胞瘤术后骨缺损,从手术技术、肿瘤复发情况、肢体关节功能等方面全面综合评价此方法临床应用效果。结果:21例患者均获得骨性愈合,无骨折及内固定断裂发生,2例复发,复发率9.8%;肢体关节功能优18例(85.7%)、良3例(14.3%)、中差0例。结论:微波高温能彻底杀灭肿瘤组织降低复发率,自体髂骨保证与近关节软骨下骨愈合,异体骨粒复合骨水泥能良好充填残余瘤腔、且具有良好的生物力学性能,以防发生关节软骨面塌陷。