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PubMed2006

Biological stability and osteoconductivity in rabbit tibia of pulsed laser deposited hydroxylapatite coatings.

A comparative study of the biological stability and the osteoconductivity of hydroxylapatite (HA) coatings produced by pulsed laser deposition (PLD) and plasma spraying (PS) was conducted. Three different implant groups were used: grit-blasted titanium rods coated with HA-PLD (2-microm-thick), grit-blasted titanium rods coated with HA-PS (50-microm-thick), and uncoated. Implantation took place into the proximal tibia of 12 mature New Zealand White rabbits for 24 weeks. Samples were evaluated using descriptive histology and histomorphometry. While HA-PS implants showed considerable instability and reduction in thickness after 24 weeks, but no statistical difference to the titanium group, the HA-PLD group showed a significant higher amount of bone apposition (Scheffé test, p<0.05) than the other two groups, without signs of degradation or dissolution. Remarkably, after 6 months, the almost intact thin pulsed laser deposited coating could be observed by electron microscopy in extended areas.

Animals↗

PubMed1988

Ultracytochemical investigation of calcium-activated adenosine triphosphatase (Ca++-ATPase) in chick tibia.

The ultrastructural distribution of Ca++-ATPase in bone cells of growing chick tibia was investigated by a cytochemical method in order to gain insight into possible sites of calcium ion translocation. Both osteoclasts and osteoblasts showed a polar distribution of reaction product along the plasma membrane. In osteoclasts, enzymatic activity occurred along the portion of the plasma membrane facing the marrow but not along the ruffled border or clear zone. The reaction product in these cells was due solely to Ca++-ATPase action. In osteoblasts, the plasma membrane facing away from bone (apical and lateral membrane) was very intensely stained, whereas the basal membrane was unstained. The reaction product in these cells appeared to be the result of both Ca++-ATPase and Ca++,Mg++-ATPase. In osteocytes, no plasma membrane staining was detectable. Mitochondrial staining in all three types of cells was more sensitive to fixation than was the plasma membrane enzyme, suggesting that mitochondrial and plasma membrane Ca++-ATPases are chemically distinct, as biochemical studies have shown. In general, mitochondria in osteoclasts stained more intensely than those in osteoblasts or osteocytes. Mitochondrial and vesicular sites of activity may be related to intracellular calcium storage, whereas calcium ATPases of the plasma membrane are presumed to be involved in calcium efflux from the cells. Calcitonin treatment did not alter the enzymatic distribution or intensity in osteoclasts. The striking polar distribution of both osteoclast and osteoblast plasma-membrane activity suggests that directional calcium pumping by these cells may be of importance in bone-forming and bone-resorbing mechanisms.

Aging↗

PubMed1990

Effects of parathyroid hormone, calcitonin, and dibutyryl-cyclic AMP on osteoclast area in cultured chick tibia.

Slices of osteoclast-enriched endosteal surfaces of 3 week chick tibia were cultured for 1-3 days. Osteoclasts on the bone surface were made visible by acridine orange fluorescence. Osteoclast area was measured by image analysis. Parathyroid hormone (PTH) caused osteoclasts to increase in area about 40%, and calcitonin (CT) caused a decrease in area also of about 40%. Subsequent addition of dibutyryl cyclic AMP to PTH- or to CT-treated cells resulted in a further change of 40 and 30%, respectively. Application of the cyclic AMP analog alone had no effect. All responses were rapid, occurring in 2-4 minutes.

Acridine Orange↗

PubMed1994

Immunohistochemical localization of heparan sulfate proteoglycan in rat tibiae.

Ultrastructural and immunohistochemical studies were performed to clarify the localization of heparan sulfate proteoglycans (HSPG) and their role in cell-cell and/or cell-matrix interaction of bone cells. Ultrastructural observations using the freeze-substitution method revealed electron-dense undercoat structures on the cytoplasmic side of plasma membranes and extracellular matrices in the intercellular spaces where stromal cells came in contact with hematopoietic cells and/or osteoclasts. Immunohistochemical localization of HSPG in rat tibiae was examined using monoclonal antibody directed to glycosaminoglycan of HSPG by confocal laser scanning microscopy and transmission electron microscopy. Intense immunoreactivity was detected on the basement membranes of blood vessels, as well as the plasma membranes of fibroblast-like cells surrounding them. Immunoreactivity was also seen on extracellular matrices between fibroblast-like cells and osteoclast lineage cells. In addition, osteoblasts showed moderate immunoreactivity on those plasma membranes attached to bone matrix. A postembedding method revealed gold particles in Golgi vacuoles of osteoblasts, indicating the localization of HSPG. In osteoclasts, HSPG was localized in Golgi apparatus and lysosomal structures. These findings suggest that (1) osteoblasts and osteoclast lineage cells synthesize HSPG; (2) both membrane and matrix HSPG are localized in bone tissue; and (3) HSPG may play an important role in cell-cell interaction between fibroblast-like cells and osteoclast lineage cells by reserving heparin binding growth factors and/or heparin binding adhesion molecules, such as fibronectin.

Animals↗

PubMed1995

Droloxifene prevents ovariectomy-induced bone loss in tibiae and femora of aged female rats: a dual-energy X-ray absorptiometric and histomorphometric study.

Our previous studies indicated that droloxifene (DRO), a tissue-specific estrogen antagonist/agonist, prevented bone loss without causing uterine hypertrophy in growing ovariectomized (OVX) rats. Using dual-energy X-ray absorptiometry (DXA) and bone histomorphometry, the current study compared the efficacy of DRO to 17 beta-estradiol (E2) in preventing OVX-induced bone loss in tibiae and femora of 19-month-old rats to determine whether DRO had similar skeletal effects as E2 in aged female rats. Sprague-Dawley female rats were OVX or sham-operated (sham) at 19 months of age. The sham-operated rats were treated with vehicle (oral), while the OVX rats were treated with vehicle (oral), E2 at 30 micrograms/kg/day (sc), or DRO at 2.5, 5, or 10 mg/kg/day (oral) for 8 weeks. Bone mineral density (BMD) of whole femora (WF), distal femoral metaphyses (DFM), femoral shafts (FS), and proximal femora (PF) was determined using DXA. Static and dynamic cancellous bone histomorphometric analyses were performed in double-labeled undecalcified longitudinal sections from proximal tibial metaphyses. Ovariectomy for 8 weeks significantly reduced the BMD of WF, DFM, FS, and PF (from -6 to -15%). Treatment with E2 completely prevented the decreases in BMD of WF and DFM and had no significant effects in BMD of FS and PF in aged OVX rats. The decrease in BMD of DFM induced by OVX was prevented by treatment with DRO at all dose levels. In addition, DRO at 10 mg/kg/day prevented OVX-induced decreases in BMD of WF, FS, and PF.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗

PubMed1996

Ultrastructural, enzyme-, lectin, and immunohistochemical studies of the erosion zone in rat tibiae.

To clarify the process of endochondral ossification, we used ultrastructural, enzyme-, lectin-, and immunohistochemical techniques to study perivascular cells located in the erosion zones of rat tibiae. In growth plate erosion zones, perivascular cells directly connected to blood capillaries were seen invading cartilage. These cells contained a well-developed rough endoplasmic reticulum and Golgi apparatus in their cytoplasm and formed finger-like cytoplasmic processes toward uncalcified transverse cartilage walls. These processes were seen to stretch as far as the degenerated chondrocytes located in the calcified layer of the growth plate. Interestingly, these perivascular cells showed neither alkaline phosphatase activity nor tartrate-resistant acid phosphatase activity. Lectin histochemistry revealed specific staining by Dolichos Biflorus agglutinin (DBA) on the perivascular cells. No reactivity for DBA was detected on either endothelial cells, osteoblasts, chondroclasts, or osteoclasts. In addition, immuno-histochemical studies showed that the perivascular cells neither expressed CD44, which was localized on the plasma membrane of chondroclasts, osteoclasts, and osteocytes, nor were surrounded by laminin. These results suggest that the perivascular cells in the erosion zone are distinct from endothelial cells, osteoblasts, chondroclasts, and osteoclasts; that they may resorb uncalcified cartilage matrix and degenerated chondrocytes; and that perivascular cells may play an important role in the capillary invasion during the process of endochondral ossification.

Acid Phosphatase↗

PubMed1982

A biochemical and morphological investigation of alkaline phosphatase and Ca+2-ATPase during initial mineralization in chick embryonic tibia.

Biochemical analysis of the enzymes alkaline phosphatase and Ca+2-ATPase in the membrane fraction obtained from chick embryonic tibias showed a positive correlation between the elevated activity of these two enzymes and the onset of mineralization. Histochemistry further showed an increased intensity of alkaline phosphatase at the time of the onset of mineralization. It seems that both of these enzymes are involved in the process of mineralization.

Alkaline Phosphatase↗

PubMed1988

Sex differences in age-related remodeling of the femur and tibia.

Changes with age in cross-sectional geometry of the lower limb bones were investigated in a large sample of cadaveric skeletal material from U.S. white adults. Section properties (areas and second moments of area) were determined at 11 locations by sectioning and direct measurement of 103 femora and 99 tibiae. All properties were standardized for body size differences by dividing by powers of bone length, and age trends were determined through linear regression analysis. Results indicate that while both men and women undergo endosteal resorption of bone and medullary expansion with aging, only men exhibit concurrent subperiosteal bone apposition and expansion. As a consequence, men show little change in cortical area and some increase in second moments of area with age, while women show decreases in both cortical area and second moments of area. Thus, only men appear to remodel bone in a way that would tend to compensate for loss of bone material strength with aging. In a previous study of a preindustrial sample with high activity levels, both men and women exhibited bone subperiosteal expansion and increase in second moments of area with aging. Together with observed differences in fracture incidence among living populations, these findings suggest that relatively low activity levels may not stimulate optimal bone remodeling throughout life and thus may contribute to higher risk of fracture in old age.

Adult↗

PubMed1989

Density changes at the proximal tibia after medial meniscectomy.

Trabecular bone density changes at the proximal tibia were studied after total and partial meniscectomy using quantitative computerized tomography. Thirty-seven medially meniscectomized patients (5- and 10-year follow-up) and 10 control persons were included. In the partially and the totally meniscectomized knees, the area of maximal density in the medial tibial condyle was displaced approximately 4 mm in a posteromedial direction relative to the position in the intact knees. In both partially and totally meniscectomized knees, the density in the region of tibiofemoral contact in the medial tibial condyle was higher compared with the density in the same region in the contralateral intact knees. This difference was of the same order in the 5- and 10-year follow-up groups. The density difference between the meniscectomized and the intact knees in the region of tibiofemoral contact in the medial condyle was significantly higher in totally than in partially meniscectomized patients. It is concluded that not only total but also partial medial meniscectomy is followed by density changes, occurring within the first 5 years after meniscectomy. The results emphasize the importance of the utmost conservatism in surgery on the meniscus.

Adult↗

PubMed1990

Transcortical streaming potentials are generated by circulatory pressure gradients in living canine tibia.

Electrical potentials associated with the pulse pressure have been observed in a canine tibia model in vivo. As the medullary pressure rises during pulsing, the periosteal bone surface becomes positive with respect to the endosteal surface. This pattern is consistent with streaming potentials generated by outward flow of fluid through bone with a negatively charged matrix (negative zeta potential). Both the medullary pressure and electric potential oscillations are halted by occlusion of the femoral artery. Furthermore, systemic administration of epinephrine decreases the amplitude of the medullary pressure and the electric potential by the same fraction. Streaming potentials generated by blood flow are distinct from those generated by mechanical deformation and may have additional significance in relation to fracture healing and/or etiology of osteoporosis.

Animals↗

PubMed1990

Effect of direct current stimulation on bone growth after distraction epiphysiolysis of the rabbit tibia.

The effect of direct current stimulation on bone formation during limb lengthening was tested in a lower leg lengthening model in the rabbit. Limb lengthening was performed by distraction epiphysiolysis. A specially designed external distraction device was placed at the tibia. The distractor allowed 10 mm of lengthening in 4 weeks. Two weeks after starting the distraction, a platinum electrode was passed through the anterior cortex below the tibial tuberosity and advanced via the medullary cavity so that the tip rested in the elongated zone. Stimulation started at the time of placement of the electrodes and was continued for 3 weeks. The electrode in the elongated zone served as the cathode; the anode was placed subcutaneously. A 20 microA stimulus was selected. A control group received the same treatment without stimulation. Bone formation in the elongated zone was evaluated by histology and scintigraphy. The data from this experiment show that direct current stimulation in the early phase of a limb lengthening procedure had no effect on the extent of bone formation in the elongated zone.

Animals↗

PubMed1992

The effect of hypothermic ischemia on the alpha-adrenergic mechanisms of the canine tibia vascular bed.

The effect of hypothermic ischemia on alpha-1 and -2 adrenergic receptor mediated vasoconstriction has been studied in an in vitro perfused canine tibia preparation. Bones were perfused at a constant rate with aerated (95% O2, 5% CO2) modified Krebs Ringer solution and the effect of bolus injections of norepinephrine (0.025-6.4 nmol) on the perfusion pressure was studied. For all bones the first dose-response curve was produced under control conditions. In one group the second dose-response curve was generated during a constant infusion of prazosin (alpha-1 adrenergic antagonist); in another it was produced during a constant infusion of rauwolscine (alpha-2 adrenergic antagonist); in the control group it was generated under control conditions. The results demonstrate that, after 48 h of hypothermic ischemia, alpha-1 adrenergic-mediated vasoconstriction was significantly attenuated (p less than 0.001). However, alpha-2 adrenergic-mediated vasoconstriction was unaffected by increasing periods of hypothermic ischemia.

Animals↗

PubMed1995

Comparison of the electrical and dielectric behavior of wet human cortical and cancellous bone tissue from the distal tibia.

We compared the electrical and dielectric properties of wet human cortical and cancellous bone tissue from the distal tibia. The relationships between the electrical and dielectric behavior of cortical and cancellous bone and variables of measurement such as frequency and direction (orientation) were evaluated. In general, the resistivity of human cortical bone was found to be approximately 3.1 times more than that of cancellous bone in the longitudinal direction and least 25 times more in the transverse directions. The dielectric permittivity of human cortical bone was approximately 3.9 times that of cancellous bone in the longitudinal direction, whereas in the transverse directions it was about 0.65 times greater. Measurement variables such as frequency and orientation appeared to affect cancellous and cortical bone differently. Strong correlations were found between the electrical properties in one direction and the electrical properties in the other two directions; however, these relationships differed for the samples of cortical and cancellous bone.

Animals↗

PubMed2006

Adamantinoma of tibia: a study of 12 cases.

BACKGROUND: Adamantinoma is a rare tumor of long bones that can be mistaken for a carcinoma, and numerous other lesions such as myoepithelial tumor, malignant mixed tumor of bone, fibrous dysplasia/osteofibrous dysplasia, and vascular tumors. METHODS: The histology and clinical features of 12 cases accrued from the surgical pathology files over a period of 23 years were analyzed. RESULTS: Of the 12 cases, 4 were men and 8 women, with a mean age of 30 years. Radiologically the tumor presented as a lytic, eccentric, intracortical lesion in the tibia. The histology revealed epithelial islands with basaloid, spindle, and squamous features on a background of fibrotic stroma. Three patients came back with local recurrences, and one of them developed pulmonary metastasis. DISCUSSION: In this article, an attempt is made to study the morphology, biology, and the differential diagnoses of adamantinoma of long bones.

Adamantinoma↗

PubMed1987

Energy requirements for osteotomy of femora and tibiae with a moving CW CO2 laser.

This paper describes the laser cutting and the amount of laser energy needed to remove a unit mass of compact or cancellous human cadaveric bones ("heat-of-removal") by using a CO2 laser. Data are collected under different operating conditions, such as laser power, scanning speed, and lens focusing for fresh and fixed human bones from male and female femora and tibiae samples with ages varying between 28 and 73 years old. The aim of the present experiments was to demonstrate the feasibility of laser osteotomy, to find the energy requirements for given groove depths or bone removal rates, and to shed some light on optimum conditions for laser osteotomy. Only cadaveric bones were used in this study, since the present aim did not include the investigation of heating rates and the extent and effect of thermal necrosis adjacent to the cut. In vivo properties may be somewhat different from those of cadaveric material. While blood circulation within the living bone may contribute to the laser cutting characteristics, it cannot be addressed here. Experiments showed that very deep cuts are difficult to achieve with a CO2 laser, as at high-power/low-scan-speed the groove becomes rather wide, with unacceptable thermal damage adjacent to the cut, while multiple passes do not easily attain large depths. There was no significant difference for the laser heat-of-removal for different age groups and for male and female samples. The laser heat-of-removal was found to be higher for compact bone than for cancellous bone samples. Comparison of cross-sections of the cuts with an existing model gave good agreement.

Adult↗

PubMed1994

Treatment of congenital pseudarthrosis of the tibia by microsurgical fibula transfer.

Conventional methods for the treatment of congenital pseudarthrosis of the tibia (CPT) often lead to unsatisfactory results and so microsurgical fibula transfer (MFT) has appeared as an option to treat this challenging problem. In this series of 27 patients with CPT, we obtained satisfactory results in 23 as assessed by the timing of bone union and bone hypertrophy of the fibular transplant. The overall functional results were also good; in 18 patients, the residual shortening was less than 2 cm (with no limb shortening in 4) and in 7, shortening ranged between 2 and 4 cm. All 25 patients resumed normal walking without the help of braces after an average of 12 months. This report suggests that microvascular fibula transfers provide superior results in the treatment of CPT, especially when considering that many of such cases represented previous surgical failures.

Child↗

PubMed2002

Chondrodysplasia punctata (CDP) with features of the tibia-metacarpal type and maternal phenytoin treatment during pregnancy.

We describe a 2-year-old boy with chondrodysplasia punctata (CDP). The boy was exposed to phenytoin, in combination with carbamazepine, during pregnancy. There has been previous evidence for a connection between phenytoin exposure during pregnancy and chondrodysplasia punctata. The boy had clinical and some radiological characteristic features of CDP, of the tibia-metacarpal type. We know of no other report on a child exposed to phenytoin during pregnancy who developed CDP of this type.

Anticonvulsants↗

PubMed1996

Type X collagen isolated from the hypertrophic cartilage of embryonic chick tibiae contains both hydroxylysyl- and lysylpyridinoline cross-links.

Hypertrophic cartilage from the tibiotarsus of Day 20 chick embryonic tibiae was found to contain an unusually high concentration of lysylpyridinoline (LP), a nonreducible collagen cross-link normally found only in bone and dentin but not in cartilage. Since type X collagen is abundant in this cartilage, research was conducted to see if type X was the primary source of LP. The 45-kDa pepsin-resistant form of type X was purified by immunoaffinity chromatography. It contained a high concentration of the LP cross-link while type II contained primarily hydroxylysylpyridinoline (HP), the predominant cross-link in cartilage. This, to our knowledge is the first time that type X has been shown directly to form nonreducible cross-links and that a collagen other than type I has a high level of LP. Also, it is interesting that the HP and LP cross-links are found in a collagen that is degraded so rapidly. Possible explanations for these findings are discussed.

Amino Acids↗