Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Bone Remodeling”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

[Bone remodeling assessment after total hip replacement].

It is known that total hip arthroplasties (THA) lead to adaptative remodeling changes resulting in periprosthetic bone loss. DEXA is recognized as the most precise and accurate method for quantifying bone mineral density (BMD) in humans. The present study compares over two years after THA, DEXA data to those of urinary deoxypyridinoline (uDPYR), a pyridinium crosslink of bone collagen fibrils proven to be a reliable bone resorption marker. 41 patients (21 postmenopausal female, 20 male) underwent cemented THA. Urinary excretion of DPYR was determined using ACS : 180 SE (Bayer Diagnostics) and normalized for creatinine excretion while periprosthetic BMD (g/cm2) was measured (QDR 4500, Hologic), at post-operative day, 3 months, 1 year and 2 years after surgery. The 7 periprosthetic subregions (R1-R7) of the Gr en method are the regions of interest for evaluating bone remodeling process. uDPYR showed a significant decrease between postoperation and 1 year: 10.6 0.80 vs 4.8 0.6 nmol/mmol, p < 0.0001 (Wilcoxon Test for paired samples and statistical significance accepted at p < 0.05) and non significant variation between 1 and 2 years. Between post-operation and 3 months global and regional BMDs decrease significantly (p < 0.04) followed by an increase in distal BMD (R3, R4, R5). During the second year BMD increases also for other regions. At 2 years BMD in distal regions is recovered except in the proximal R7 when comparing post-operation and 2 years, pattern consistent with literature. Thus, a discrepancy is observed between uDPYR and DMO results that does not allow us to use a bone resorption urinary marker to monitore local bone periprosthetic remodeling.

Adult↗
PubMed2000

Evaluation of periprosthetic bone-remodeling after cementless total hip arthroplasty. The influence of the extent of porous coating.

BACKGROUND: Total hip arthroplasty changes the levels of stress within the proximal part of the femur, and the femur remodels adjacent to the prosthesis. The stem size and the initial bone-mineral density around the distal portion of the stem affect postoperative bone-remodeling after the insertion of a fully porous-coated metal-cancellous prosthesis. The purpose of this study was to evaluate the influence of the extent of porous coating of this prosthesis on femoral bone-remodeling. METHODS: A longitudinal examination of sixty-one hips in fifty-four patients was performed. Thirty-one hips in twenty-seven patients with a fully porous-coated stem (Group A) and thirty hips in twenty-seven patients with a proximally porous-coated stem (Group B) were followed for twenty-four to thirty months. Periprosthetic bone-mineral density was measured with dual-energy x-ray absorptiometry at specific intervals after the operation. RESULTS: In both groups, the greatest loss of bone-mineral density, compared with the initial (three-week) value, was approximately 20 percent in zone 7 at twelve to eighteen months. In other zones, bone-remodeling appeared to cease by twelve months. At the last follow-up evaluation, the loss of bone-mineral density in the distal and middle regions in Group A was significantly greater than that in Group B (p < 0.01 for zone 3 and p < 0.05 for zone 6). In contrast, with the numbers available, there were no significant differences in loss of bone-mineral density in the proximal regions (zones 1 and 7) between the two groups at any follow-up period. CONCLUSIONS: The extent of porous coating affects bone-remodeling in the distal periprosthetic region rather than in the proximal region. The results in the present report are specific to the particular implants that were studied.

Absorptiometry, Photon↗
PubMed1985

Changes in bone remodeling after palatal surgery.

It is generally well known that an infant with a cleft palate will have facial underdevelopment after corrective surgery. In such a case, we can suppose that the internal remodeling of the facial bone becomes abnormal postoperatively. The purpose of this study was to observe the changes in palatal bone remodeling after palatal surgery and the external bone growth inhibition using the microradiography and hard tissue labeling method. In this investigation we had 4 experimental groups and used large undecalcified ground sections to observe the whole palatal bone. Our experiments showed that the changes resulting from surgery include not only external bone growth inhibition, but also considerable abnormal remodeling in the interior of the bone. When the mucoperiosteum was removed, the changes continued to occur for an especially long period.

Animals↗
PubMed1996

The effects of long-term hormone replacement therapy on bone remodeling in postmenopausal women.

Hormone replacement therapy prevents menopausal bone loss and reduces the risk of fragility fracture, but its effects on bone remodeling have not been clearly established. We studied the effects of long-term hormone replacement therapy on bone turnover and remodeling balance in 22 postmenopausal women with osteopenia or osteoporosis. Iliac crest biopsies were obtained before and after treatment (mean 23.5 months) after double tetracycline labeling and subjected to histomorphometric analysis. Post-treatment biopsies showed a significant reduction in bone formation rate at tissue level and activation frequency (p = 0.002 and 0.01, respectively). There was also a reduction in mineral appositional rate (p = 0.0002) and osteoid seam width (p = 0.01), but no significant change in mineralization lag time or osteoid maturation period. Wall width showed a significant decrease after treatment (p = 0.03) and there was a consistent trend toward a reduction in resorption cavity dimensions with a statistically significant decrease in the resorption cavity length (p = 0.03). These results confirm the previously reported reduction in bone turnover in postmenopausal women treated with hormone replacement therapy. Post-treatment biopsies also showed a reduction in resorption cavity size and a decrease in wall width, the latter possibly reflecting a compensatory change in response to the reduction in erosion depth. Our data do not provide any evidence that conventional hormone replacement therapy has anabolic effects at the level of the bone remodeling unit and indicate that its beneficial skeletal effects result from suppression of bone turnover and a reduction in the size of resorption cavities.

Adult↗
PubMed1991

Effects of ossein-hydroxyapatite compound on ewe bone remodeling: biochemical and histomorphometric study.

Ossein-hydroxyapatite compound (OHC) is a protein-mineral complex derived from bovine bone. Its effects on bone remodeling were studied in old ewes which have seasonal variations in bone remodeling. Seven animals received 200 mg OHC/kg b.w./day for 90 days from July to September. The control group consisted of 7 untreated animals followed for the same period of time. OHC was administered through a fistula into the fourth stomach. A significant decrease of bone histomorphometric parameter values was noted in controls at the end of the experiment, due to seasonal variations: the cancellous eroded perimeter decreased by 45%, the osteoblastic perimeter by 60% and the bone formation rate at the cell level by 20%. In contrast, in the treated-group, these parameters tended to increase or did not change. In conclusion, counteracting the significant seasonal reduction of bone remodeling in ewes, OHC seems able to stimulate directly or indirectly bone metabolism, especially when osteoblast activity is reduced and may partly prevent the seasonal reduction of bone turnover.

Animals↗
PubMed2001

Diacerein reduces the excess synthesis of bone remodeling factors by human osteoblast cells from osteoarthritic subchondral bone.

OBJECTIVE: Although cartilage degradation characterizes osteoarthritis (OA), there is evidence that remodeling of subchondral bone in this disease is a contributing factor. Therapeutic strategies to modify the metabolism of subchondral bone osteoblasts may be indicated to treat OA. We studied the effects of diacerein and rhein on the metabolic and inflammatory variables of OA subchondral osteoblasts. METHODS: Human OA primary subchondral osteoblast cells were used. The effect of diacerein and rhein at therapeutic concentrations (5-20 microg/ml) was determined by osteoblast phenotypic factors, alkaline phosphatase, osteocalcin, and cAMP; on metabolic agents urokinase plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1), and insulin-like growth factor-1 (IGF-1); and on inflammatory mediators interleukin 6 (IL-6), prostaglandin E2 (PGE2), and cyclooxygenase-2 (COX-2). RESULTS: Diacerein and rhein did not affect either basal and 1,25(OH)2D3 induced alkaline phosphatase or parathyroid hormone (PTH) stimulated cAMP formation. Conversely, they dose dependently and statistically inhibited 1,25(OH)2D3 induced osteocalcin release, a situation explained by a reduction of mRNA levels for osteocalcin. Of the metabolic factors, they inhibited the production of uPA, with rhein showing slightly more potency; inhibitions of 69% and 57% were reached at the highest concentration (20 microg/ml) of rhein and diacerein, respectively. Both drugs also inhibited the PAI-1 level, albeit at a much lower level than for uPA. Interestingly, determination of the uPA/PAI1 ratio revealed that both drugs inhibited it about 55%, suggesting a decrease in uPA activity. In contrast, IGF-1 levels only increased slightly when cells were treated with rhein but not with diacerein. A transient dose dependent effect was found on IL-6 production; an inhibition was noted at low drug concentrations, which returned to basal levels at the highest concentration tested. PGE2 levels increased exponentially and were related to a concomitant increase in COX-2 levels in response to both drugs. CONCLUSION: Our data indicate that diacerein and rhein do not appear to affect OA subchondral bone cells' basal cellular metabolism, yet both agents reveal a direct effect at reducing the synthetic activities of osteoblasts, which could be responsible for abnormal subchondral bone remodeling occurring during the course of OA.

Aged↗
PubMed1999

Effect of stem stiffness and bone stiffness on bone remodeling in cemented total hip replacement.

The hypothesis in this study is that the stem stiffness-to-bone stiffness ratio influences the incidence and type of bone remodeling and fixation with cemented total hip arthroplasty. Ninety-one patients with 99 hips had cemented stems using 3 different anatomic porous replacement designs. The APR I and APR II titanium stems with proximal porous coating on the proximal one fourth of the stem were cemented into 49 and 35 patients. The APR II-C stem, which is a cobalt-chrome stem only for cemented fixation, was cemented into 15 patients. These 3 different stem designs were used to study different metals as well as different stem shapes. The average follow-up was 4.3 years (range, 2-10 years) with all hips having 2 years' follow-up and 42 hips at least 5 years' follow-up. Bone remodeling was measured as stress shielding, calcar resorption, and distal hypertrophy on anteroposterior and lateral radiographs of the hip. Stress shielding was measured by the 4 grades described by Engh. A stem stiffness-to-femoral bone stiffness ratio was calculated from the plain radiographs with the stem stiffness known from the manufacturer and the bone stiffness calculated using measurements of the outer and inner diameters of the femur. There was no statistical difference for bone remodeling and fixation between the 3 stem shapes or 2 metal types used in these hips. No stem was loose, and only 10 had radiolucent lines. Stress shielding was statistically related to stem stiffness but was more strongly related to the axial stiffness ratio, mediolateral bending stiffness ratio, anteroposterior stiffness ratio, and torsional stiffness ratio. Stress shielding grade 3 and 4 was present in 20% of hips with a torsional stiffness ratio < 0.33, in 38% of hips with a torsional stiffness ratio of 0.34 to 0.5, and in 70% of hips with a torsional stiffness ratio > 0.5. Five-year results showed no statistical change in stress shielding, calcar resorption, and distal hypertrophy from the 2-year observations. The stem stiffness-to-bone stiffness ratio influenced bone remodeling but not fixation of these cemented stems.

Adult↗
PubMed1999

[Physical activity, bone remodeling, and osteoporosis].

Scientific publications have produced debate about the action of the physical activity in the osteoporosis. It's condition by several factors, like the repercussion of the physical activity in the bone remodeling, the loss of bone mass with immobilization or the gravitational effect. The progressive knowledge of the different nutritional and direct and indirect biochemical factors that stimulates, inhibits or modulates the bone remodeling, and the new methodology in the evaluation of the bone mineral density and the biomarkers of bone resorption or bone formation have confirmed or denied the results apparently contradictory. We analyse the advantages of the action of the physical activity in the normal bone remodeling process, his risk factors in some deportive actions. The not confirmation of the therapeutic utility of the physical activity in the osteoporosis, and the actual research about the amount of bone that can be gained by activity or high bone mass in a determined age, with special emphasis in the activity for tension of muscular contraction and the percussion effect for the specific sport action.

Body Mass Index↗
PubMed1996

Bone remodeling around implanted ceramics.

Bone formation and remodeling around implanted materials is influenced by the kind of material, its surface properties, and the anatomical site of implantation. In this study, differences in bone formation around three kinds of ceramics and the importance of the implant location in the tibia were investigated. In the first experiment, we placed three kinds of ceramics--alumina, zirconia and hydroxyapatite (HA)--into the medullary cavity of rabbit tibiae and examined histologically the time-dependent formation of bone around the materials for up to 24 weeks postoperatively. We found that bone formation depends on whether or not the materials are in direct contact with the endosteum. In the second experiment, the same three ceramic materials were implanted transcortically into rabbit tibiae. The bone formed around the implants was most abundant in regions adjacent to the periosteum, followed by the endosteum and the marrow cavity in the approximate ratios of 70%, 40%, and 10%, respectively. In these two experiments, the difference between bioactive and bioinert ceramics could be seen in the interface between the implanted material and the bone. It can be concluded that bone formation around these materials is related to the osteoconductivity of the materials and to the osteogenic capacity of the tissues.

Aluminum Oxide↗
PubMed1987

Exogenous triiodothyronine activates bone remodeling.

The effect of exogenous triiodothyronine (T3) as an activator of bone remodeling was investigated by measuring biochemical marker levels. Fourteen people received 100-160 micrograms of T3 for 1 week and were followed for a total of 10 weeks. Serum T3 increased markedly during the first week, whereas serum TSH and serum thyroxine (T4) decreased. Bone resorption was stimulated during the first week as evaluated from serum calcium and renal excretion of calcium, phosphate, and hydroxyproline. Serum osteocalcin showed an increase in the first week, probably caused by stimulation of existing osteoblasts. Serum alkaline phosphatase increased from week 6 to week 8, and serum osteocalcin increased at week 8 to a level higher than the initial level. The results indicate that T3 acts as an activator of bone remodeling and initiates bone resorption followed by bone formation. The observed timetable for the remodeling sequence is in accordance with that obtained by bone histomorphometry. Osteopenic states may be treated by synchronizing the skeletal remodeling processes and then selectively depressing bone resorption with calcitonin or diphosphonates (ADFR treatment). Synchronization may be achieved by short-term treatment with a drug that stimulates the formation rate of new remodeling cycles (an activator). The results from this study indicate that exogenous T3 may be used as an activator.

Adult↗
PubMed2001

A mechanistic model for internal bone remodeling exhibits different dynamic responses in disuse and overload.

Bone is a dynamic tissue which, through the process of bone remodeling in the mature skeleton, renews itself during normal function and adapts to mechanical loads. It is, therefore, important to understand the effect of remodeling on the mechanical function of bone, as well as the effect of the inherent time lag in the remodeling process. In this study, we develop a constitutive model for bone remodeling which includes a number of relevant mechanical and biological processes and use this model to address differences in the remodeling behavior as a volume element of bone is placed in disuse or overload. The remodeling parameters exhibited damped oscillatory behavior as the element was placed in disuse, with the amplitude of the oscillations increasing as the severity of disuse increased. In overload situations, the remodeling parameters exhibited critically sensitive behavior for loads beyond a threshold value. These results bear some correspondence to experimental findings, suggesting that the model may be useful when examining the importance of transient responses for bone in disuse, and for investigating the role fatigue damage removal plays in preventing or causing stress fractures. In addition, the constitutive algorithm is currently being employed in finite element simulations of bone adaptation to predict important features of the internal structure of the normal femur, as well as to study bone diseases and their treatment.

Animals↗
PubMed1992

Effects of ipriflavone on bone remodeling in primary hyperparathyroidism.

The aim of this study was to evaluate the effects of ipriflavone treatment on bone remodeling in primary hyperparathyroidism. Nine patients, 6 females and 3 males (mean +/- SD age 56 +/- 12.5 years) were treated with 1200 mg/day of ipriflavone by oral administration divided in 3 daily doses. All patients were treated for 21 days; in 5 patients treatment was prolonged to 42 days. In all patients the main serum and urinary parameters of bone remodeling were evaluated. The results suggest that ipriflavone affects bone remodeling by inhibiting bone resorption without affecting bone formation. Ipriflavone is, therefore, indicated in the treatment of metabolic bone diseases characterized by a high bone turnover.

Adult↗
PubMed2005

Computational bone remodelling simulations and comparisons with DEXA results.

Femoral periprosthetic bone loss following total hip replacement is often associated with stress shielding. Extensive bone resorption may lead to implant or bone failure and complicate revision surgery. In this study, an existing strain-adaptive bone remodelling theory was modified and combined with anatomic three-dimensional finite element models to predict alterations in periprosthetic apparent density. The theory incorporated an equivalent strain stimulus and joint and muscle forces from 45% of the gait cycle. Remodelling was simulated for three femoral components with different design philosophies: cobalt-chrome alloy, two-thirds proximally coated; titanium alloy, one-third proximally coated; and a composite of cobalt-chrome surrounded by polyaryletherketone, fully coated. Theoretical bone density changes correlated significantly with clinical densitometry measurements (DEXA) after 2 years across the Gruen zones (R2>0.67, p<0.02), with average differences of less than 5.4%. The results suggest that a large proportion of adaptive bone remodelling changes seen clinically with these implants may be explained by a consistent theory incorporating a purely mechanical stimulus. This theory could be applied to pre-clinical testing of new implants, investigation of design modifications, and patient-specific implant selection.

Absorptiometry, Photon↗
PubMed2000

Loss of osteocyte integrity in association with microdamage and bone remodeling after fatigue in vivo.

As a result of fatigue, bone sustains microdamage, which is then repaired by bone-remodeling processes. How osteoclastic activity is targeted at the removal of microdamaged regions of bone matrix is unknown. In the current studies, we tested the hypothesis that changes in osteocyte integrity, through the initiation of regulated cell death (apoptosis), are associated with fatigue-related microdamage and bone resorption. Ulnae of adult rats were fatigue-loaded to produce a known degree of matrix damage. Osteocyte integrity was then assessed histomorphometrically from terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labeling (TUNEL)-stained sections to detect cells undergoing DNA fragmentation associated with apoptosis; toluidine blue-stained sections were used for secondary morphological confirmation. Ten days after loading, large numbers of TUNEL-positive osteocytes were found in bone surrounding microcracks and in bone surrounding intracortical resorption spaces (approximately 300% increases over controls, p < 0.005). TUNEL labeling in loaded ulnae at sites distant from microcracks or resorption foci did not differ from that in control bone. Osteocytes in toluidine blue-stained sections showed equivalent trends to TUNEL-stained sections, with significant increases in pyknotic nuclei and empty lacunae associated with microcracks and intracortical resorption spaces. TUNEL-positive osteocytes were observed around bone microdamage by 1 day after loading (p < 0.01 relative to baseline), and their number remained elevated throughout the entire experimental period. Increases in empty lacunae and decreases in normal osteocyte numbers were observed over time as well. These studies show that (1) osteocyte apoptosis is induced by bone fatigue, (2) this apoptosis is localized to regions of bone that contain microcracks, and (3) osteoclastic resorption after fatigue also coincides with regions of osteocyte apoptosis. The strong associations between microdamage, osteocyte apoptosis, and subsequent bone remodeling support the hypothesis that osteocyte apoptosis provides a key part of the activation or signaling mechanisms by which osteoclasts target bone for removal after fatigue-induced matrix injury.

Animals↗
PubMed1994

Structural aspects of the reversal phase of alveolar bone remodelling.

The ultrastructure of the reversal line during alveolar bone remodelling was investigated in the rat. Surface bone remodelling along the periosteum of the mandible was induced by the extraction of opposing maxillary molars. With transmission EM the reversal line was seen to be composed of a superficial electron-dense amorphous layer and a deep filamentous layer at 7 d after extraction. The reversal line exhibited strong alkaline phosphatase activity and contained acid mucopolysaccharide. Scanning EM of the surface of the line, exposed by sonication in distilled water, showed papillary structures, the surface of which appeared granular and exhibited a crystalline appearance. The tips of collagen fibrils of new bone were attached to the top of the papillae in the front area of bone formation. It is suggested that the reversal line is involved in the coupling of bone resorption and formation.

Alkaline Phosphatase↗
PubMed1990

Prostaglandin E2 enhances cortical bone mass and activates intracortical bone remodeling in intact and ovariectomized female rats.

To assess the efficacy of prostaglandin E2 (PGE2) in augmenting cortical bone mass, graded doses of PGE2 were subcutaneously administered for 30 days to seven-month old sham-ovariectomized (SHAM) and ovariectomized (OVX) rats. Both groups were operated at three months of age. Histomorphometric analyses of double fluorescent labeled tibial shafts were performed on basal control, OVX, and SHAM rats treated with 0, 0.3, 1, 3, and 6 mg PGE2/kg/d for 30 days. Baseline aging data showed increased cortical tissue and cortical bone area and reduced bone formation parameters at the periosteal and endocortical bone envelopes between three and eight months of age. The tibial shafts of OVX rats compared to SHAM controls showed elevated periosteal mineral apposition rate and endocortical bone formation parameters. PGE2 administration to OVX and SHAM rats increased cortical bone by the addition of new circumferential bone on the endocortical and periosteal surfaces, as well as woven cancellous bone in the marrow region. Stimulated osteoblastic recruitment and activity enhanced bone formation at all bone surfaces. The new bone was both lamellar and woven in nature. PGE2 treatment also activated intracortical bone remodeling (not seen in untreated eight-month old rats), creating a porous cortex. Thus, PGE2 administration activated cortical bone modeling in the formation mode (A----F), as well as intracortical bone remodeling (A----R----F). PGE2 administration to OVX rats resulted in more intracortical bone remodeling, periosteal bone formation, and new cancellous bone production than observed in PGE2 treated controls. The findings that PGE2 administration to OVX and intact female rats increases cortical bone mass, coupled with observations that mouse, rat, dog, and man respond similarly to PGE2, suggest that PGE2 administration may be useful in the prevention and treatment of postmenopausal osteoporosis.

Aging↗
PubMed2005

Aromatase and regulation of bone remodeling.

Estrogens play a key role in regulating bone mineralization. Bone tissue expresses the enzymes that metabolize estrogens, as well as the alpha and beta receptors that mediate responses to estrogens. After the menopause, estrogen secretion by the ovaries is promptly replaced by production within tissues, which occurs chiefly via aromatization of adrenal steroids. Therefore, aromatase activity is a major determinant of estrogen activity in postmenopausal women. Studies are beginning to shed light on the mechanisms by which aromatase activity influences bone remodeling.

Animals↗