Changes In Cortical Bone Research Articles

Stress fractures in the elderly: different pathogenetic features compared with young patients

Stress fractures mainly occur in the lower limb as a result of cyclic submaximal stresses. Most commonly affected by this specific type of fractures are young athletes, military or elderly subjects with metabolic bone diseases like osteoporosis. In consideration of the heterogeneity of affected patients is presumable that there are different pathogenic mechanisms. In young person bone tissue, although metabolically intact, is not able to withstand the stresses to which it is chronically subjected, also because of muscle fatigue. This leads to a macrostructural failure and to the development of "fatigue" fractures. Instead, in elderly patients, there are numerous physiological conditions that determine a bone metabolism alteration. This is the main reason for the structural changes in trabecular and cortical bone, which is reflected in reduced biomechanical strength. In addition, muscular situation, such as muscle fiber atrophy, is unable to correctly support bone tissue, leading to the development of insufficiency fractures.

Elevated mechanical loading when young provides lifelong benefits to cortical bone properties in female rats independent of a surgically induced menopause.

Exercise that mechanically loads the skeleton is advocated when young to enhance lifelong bone health. Whether the skeletal benefits of elevated loading when young persist into adulthood and after menopause are important questions. This study investigated the influence of a surgically induced menopause in female Sprague-Dawley rats on the lifelong maintenance of the cortical bone benefits of skeletal loading when young. Animals had their right forearm extrinsically loaded 3 d/wk between 4 and 10 weeks of age using the forearm axial compression loading model. Left forearms were internal controls and not loaded. Animals were subsequently detrained (restricted to cage activities) for 94 weeks (until age 2 years), with ovariectomy (OVX) or sham-OVX surgery being performed at 24 weeks of age. Loading enhanced midshaft ulna cortical bone mass, structure, and estimated strength. These benefits persisted lifelong and contributed to loaded ulnas having greater strength after detraining. Loading also had effects on cortical bone quality. The benefits of loading when young were not influenced by a surgically induced menopause because there were no interactions between loading and surgery. However, OVX had independent effects on cortical bone mass, structure, and estimated strength at early postsurgery time points (up to age 58 weeks) and bone quality measures. These data indicate skeletal loading when young had lifelong benefits on cortical bone properties that persisted independent of a surgically induced menopause. This suggests that skeletal loading associated with exercise when young may provide lifelong antifracture benefits by priming the skeleton to offset the cortical bone changes associated with aging and menopause.

SAT0095 Periarticular Bone Loss in Female Patients with Rheumatoid Arthritis: A Case-Control Study Using HR-PQCT

BackgroundPeriarticular bone loss is an early sign of bone involvement in rheumatoid arthritis (RA) and a predictor of subsequent radiographic erosion. High-resolution peripheral quantitative computed tomography (HR-pQCT) is a non-invasive...

Reference point indentation study of age-related changes in porcine femoral cortical bone

The reference point indentation (RPI) method is a microindentation technique involving successive indentation cycles. We employed RPI to measure average stiffness (Ave US), indentation distance increase (IDI), total indentation distance (TID), average energy dissipated (Ave ED), and creep indentation distance (CID) of swine femoral cortical bone (mid-diaphysis) as a function of age (1, 3.5, 6, 14.5, 24, and 48 months) and loading directions (longitudinal and transverse). The Ave US increases with animal age, while the IDI, TID, Ave ED, and CID decrease with age, for both longitudinal (transverse surface) and transverse (periosteal surface) loading directions. Longitudinal measurements generally give higher Ave US and lower IDI and TID values compared to transverse measurements. The RPI measurements show similar trends to those obtained using nanoindentation test, and ash and water content tests.

Bone loss before the clinical onset of rheumatoid arthritis in subjects with anticitrullinated protein antibodies

ObjectiveAnticitrullinated protein antibodies (ACPA) are a major risk factor for bone loss in rheumatoid arthritis (RA). We have recently shown that ACPA directly induce bone loss by stimulating osteoclast differentiation....

Alterations in the osteocyte lacunar–canalicular microenvironment due to estrogen deficiency

While reduced estrogen levels have been shown to increase bone turnover and induce bone loss, there has been little analysis of the effects of diminished estrogen levels on the lacunar–canalicular porosity that houses the osteocytes. Alterations in the osteocyte lacunar–canalicular microenvironment may affect the osteocyte's ability to sense and translate mechanical signals, possibly contributing to bone degradation during osteoporosis. To investigate whether reduced estrogen levels affect the osteocyte microenvironment, this study used high-resolution microscopy techniques to assess the lacunar–canalicular microstructure in the rat ovariectomy (OVX) model of postmenopausal osteoporosis. Confocal microscopy analyses indicated that OVX rats had a larger effective lacunar–canalicular porosity surrounding osteocytes in both cortical and cancellous bone from the proximal tibial metaphysis, with little change in cortical bone from the diaphysis or cancellous bone from the epiphysis. The increase in the effective lacunar–canalicular porosity in the tibial metaphysis was not due to changes in osteocyte lacunar density, lacunar size, or the number of canaliculi per lacuna. Instead, the effective canalicular size measured using a small molecular weight tracer was larger in OVX rats compared to controls. Further analysis using scanning and transmission electron microscopy demonstrated that the larger effective canalicular size in the estrogen-deficient state was due to nanostructural matrix-mineral level differences like loose collagen surrounding osteocyte canaliculi. These matrix-mineral differences were also found in osteocyte lacunae in OVX, but the small surface changes did not significantly increase the effective lacunar size. The alterations in the lacunar–canalicular surface mineral or matrix environment appear to make OVX bone tissue more permeable to small molecules, potentially altering interstitial fluid flow around osteocytes during mechanical loading.

Mapping human long bone compartmentalisation during ontogeny: A new methodological approach

Throughout ontogeny, human bones undergo differentiation in terms of shape, size and tissue type; this is a complex scenario in which the variations in the tissue compartmentalisation of the cortical bone are still poorly understood. Currently, compartmentalisation is studied using methodologies that oversimplify the bone tissue complexity. Here, we present a new methodological approach that integrates a histological description and a mineral content analysis to study the compartmentalisation of the whole mineralised and non-mineralised tissues (i.e., spatial distribution in long bone sections). This new methodology, based on Geographical Information System (GIS) software, allows us to draw areas of interest (i.e., tracing vectorial shapes which are quantifiable) in raw images that are extracted from microscope and compared them spatially in a semi-automatic and quantitative fashion. As an example of our methodology, we have studied the tibiae from individuals with different age at death (infant, juvenile and adult). The tibia's cortical bone presents a well-formed fibrolamellar bone, in which remodelling is clearly evidenced from early ontogeny, and we discuss the existence of "lines of arrested growth". Concurrent with the histological variation, Raman and FT-IR spectroscopy analyses corroborate that the mineral content in the cortical bone changes differentially. The anterior portion of the tibia remains highly pierced and is less crystalline than the rest of the cortex during growth, which is evidence of more active and continuous remodelling. Finally, while porosity and other "non-mineralised cavities" are largely modified, the mineralised portion and the marrow cavity size persist proportionally during ontogeny.

Differential effect of zoledronic acid on normal trabecular and cortical bone density in oncologic patients with bone metastases

PurposeTo evaluate bone density changes at the level of normal bone and bone metastases after zoledronic acid (ZA) treatment in oncologic patients. Materials and methodsWe retrospectively evaluated 72 consecutive adult patients with histologically confirmed solid tumors with at least 1 newly diagnosed bone metastatic lesion. Bone metastases were diagnosed by bone scans and confirmed with computed tomography (CT). Patients received intravenous ZA, 4mg, by 15-min infusion every 28 day through a peripheral or a central venous access and were monitored for at least 3 months and a maximum of 24 months. Bone density was determined at the level of bone metastases and at the level of normal trabecular and cortical bone using a ROI-based approach. ResultsA significant increase was demonstrated at the level of normal trabecular bone of the calvarium and the femoral neck. No significant increase of density was observed at the level of the normal cortical bone. Bone metastases showed a significant increase in CT density as compared to baseline up to 24 months after zoledronic acid. ConclusionWe have found that long term treatment with ZA increases trabecular bone density in oncologic patients whereas normal cortical bone changes are not detectable.

Quantitative CT with finite element analysis: towards a predictive tool for bone remodelling around an uncemented tapered stem

We used quantitative CT in conjunction with finite element analysis to provide a new tool for assessment of bone quality after total hip arthroplasty in vivo. The hypothesis of this prospective five-year study is that the combination of the two modalities allows 3D patient-specific imaging of cortical and cancellous bone changes and stress shielding. We tested quantitative CT in conjunction with finite elements on a cohort of 29 patients (31 hips) who have been scanned postoperatively and at one year, two years and five years follow-up. The method uses cubic Hermite finite element interpolation for efficient mesh generation directly from qCT datasets. The element Gauss points that are used for the geometric interpolation functions are also used for interpolation of osteodensitometry data. The study showed changes of bone density suggestive of proximal femur diaphysis load transfer with osteointegration and moderate metaphyseal stress shielding. Our model revealed that cortical bone initially became porous in the greater trochanter, but this phenomenon progressed to the cortex of the lesser trochanter and the posterior aspect of the metaphysis. The diaphyseal area did not experience major change in bone density for either cortical or cancellous bone. The combination of quantitative CT with finite element analysis allows visualization of changes to bone density and architecture. It also provides correlation of bone density/architectural changes with stress patterns enabling the study of the effects of stress shielding on bone remodelling in vivo. This technology can be useful in predicting bone remodeling and the quality of implant fixation using prostheses with different design and/or biomaterials.

Mandibular cortical bone evaluation on cone beam computed tomography images of patients with bisphosphonate-related osteonecrosis of the jaw

The objective of this study was to develop a technique for detecting cortical bone dimensional changes in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ). Subjects with BRONJ who had cone-beam computed tomography imaging were selected, with age- and gender-matched controls. Mandibular cortical bone measurements to detect bisphosphonate-related cortical bone changes were made inferior to mental foramen, in 3 different ways: within a fixed sized rectangle, in a rectangle varying with the cortical height, and a ratio between area and height. Twelve BRONJ cases and 66 controls were evaluated. The cortical bone measurements were significantly higher in cases than controls for all 3 techniques. The bone measurements were strongly associated with BRONJ case status (odds ratio 3.36-7.84). The inter-rater reliability coefficients were high for all techniques (0.71-0.90). Mandibular cortical bone measurement is a potentially useful tool in the detection of bone dimensional changes caused by bisphosphonates.

Systemic treatment with pulsed electromagnetic fields do not affect bone microarchitecture in osteoporotic rats

PurposePulsed electromagnetic fields (PEMF) are currently used in the treatment of spinal fusions and non-unions. There are indications that PEMF might also be effective in the treatment of osteoporosis. In this study we examined whether whole-body PEMF treatment affects the bone microarchitecture in an osteoporotic rat model.MethodsTwenty-week-old female rats were ovariectomised (n = 20). Four different PEMF treatment protocols based on previous experimental studies and based on clinically used PEMF signals were examined (2 h/day, 5 days/week). A control group did not receive PEMF. At zero, three and six weeks cancellous and cortical bone architectural changes at the proximal tibia were evaluated using in vivo microCT scanning.ResultsPEMF treatment did not induce any changes in cancellous or cortical bone compared to untreated controls.ConclusionsAlthough previous studies have shown strong effects of PEMF in osteoporosis we were unable to demonstrate this in any of the treatment protocols. Using in vivo microCT scanning we were able to identify small bone changes in time. Subtle differences in the experimental set-up might explain the differences in study outcomes in the literature. Since PEMF treatment is safe, future experimental studies on the effect of PEMF on bone can better be performed directly on humans, eliminating the potential translation issues between animals and humans. In this study we found no support for the use of PEMF in the treatment of osteoporosis.

Distraction-like phenomena in maxillary bone due to application of orthodontic forces in ovariectomized rats

Orthodontic forces may not only influence the dentoalveolar system, but also the adjacent and surrounding cortical bone. Since there is very limited information on this issue, we aimed to study the possible changes in maxillary cortical bone following the application of heavy orthodontic forces in mature normal and osteoporotic rats. Twenty-four 6-month-old female rats were selected and divided into an ovariectomized group and a normal group. In both groups, the rats were subjected to a 60 grFNx01 orthodontic force on the upper right first molar for 14 days. In both groups, histological sections showed that the application of this force caused hypertrophy and fatigue failure of the cortical maxillary bone. The osteogenic reaction to distraction is expressed by the formation of subperiosteal callus on the outer bony side, resembling that seen in distracted bones. From this study we concluded that heavy experimental orthodontic forces in rats affect the maxillary cortical bone. The osteogenic reaction to these forces, expressed histologically by subperiosteal callus formation, is similar to that seen in distraction osteogenesis models.

Long-Term Femoral Bone Remodeling After Cemented Hip Arthroplasty With the Müller Straight Stem in the Operated and Nonoperated Femora

We investigated the cortical bone changes in 35 patients with total hip arthroplasty operated on only for osteoarthritis with more than 10 years of follow-up and with nonrevised femoral components and without radiologic signs of loosening. The mean follow-up was 16 ± 5 years. The thicknesses of femoral cortices were measured medially and laterally at 6 levels from the first postoperative and the last follow-up x-rays. A comparison with 10 patients who had a nonoperated contralateral hip was performed. We found a significant decrease in cortical thicknesses in total hip arthroplasty. The cortical thinning was significant at all periprosthetic levels but less expressed distally. Prosthetic femora were associated with greater cortical thinning as compared with the contralateral nonoperated femora, exceeding that caused by natural aging.

Age‐related changes in organization and content of the collagen matrix in rabbit cortical bone

The organization and composition of the collagen matrix of cortical bone changes as the bone matures due to growth and mechanical loading. We aimed to investigate the composition and organization of the collagen matrix in rabbit cortical bone during maturation using Fourier transform infrared (FTIR) microspectroscopy and polarized light microscopy (PLM). FTIR and PLM findings were compared to biochemical analysis from an earlier study. Mid-diaphyseal samples from left femora of female New Zealand White rabbits were used. The animal age ranged from newborn to 18-month old (5 age groups, n = 10 per group). The bones had earlier been decalcified and evaluated with biochemistry. In this study, collagen content, orientation, collagen cross-linking and spatial heterogeneity of all parameters was evaluated. Similar results were obtained when collagen content was evaluated with FTIR and PLM compared to the collagen content assessed with BA. Collagen content, orientation and collagen maturity increased significantly until the age of 3 months and remained similar thereafter. Simultaneously, spatial heterogeneity of the measured parameters decreased. Based on these findings, it seems that the collagen matrix of rabbit bone attains its mature state around 3 months of age, which is before the overall skeletal maturity is reached.

The effects of glucocorticoid on microarchitecture, collagen, mineral and mechanical properties of sheep femur cortical bone

In this study, 18 female skeletally mature sheep were randomly allocated into three groups of six each. Group 1 (glucocorticoid-1) received prednisolone treatment (0.60 mg/kg/day, five times weekly) for 7 months. Group 2 (glucocorticoid-2) received the same treatment regime followed by observation of 3 months without treatment. Group 3 was left untreated and served as controls. All sheep received a restricted diet with low calcium and phosphorus. At sacrifice, cortical bone samples from the femur midshaft of each sheep were harvested, micro-CT scanned and subjected to three-point bending and tensile strength testing. Bone collagen and mineral were determined. Cortical porosity was significantly increased in the glucocorticoid-2 compared with the glucocorticoid-1 and control groups. Apparent density was significantly decreased in the glucocorticoid-2 compared with the glucocorticoid-1 group. Collagen content was significantly increased in the glucocorticoid-2 compared with the glucocorticoid-1 and control groups. Bone mineral content did not differ between the groups. Neither the three-point bending mechanical properties nor the tensile mechanical properties differed significantly between the groups, while there was a trend towards decreasing bending mechanical properties in the glucocorticoid-2 group. In conclusion, 7 months of glucocorticoid treatment with malnutrition had a significant impact on the cortical microarchitecture of the sheep femur midshaft. These observed changes occurred 3 months after glucocorticoid cessation, suggesting a delayed effect of glucocorticoid on cortical bone. Thus, changes in cortical bone beyond cancellous bone might further increase fracture risk in patients treated with glucocorticoids. This model might be used as a glucocorticoid-induced osteoporotic model for orthopaedic biomaterial, joint prosthesis and medical device researches.

Age-related changes in iliac crest cortical width and porosity: a histomorphometric study

Although age-related changes in cancellous bone structure in human are relatively well characterized, few studies have addressed changes in cortical bone. We have investigated age-related changes in iliac crest bone biopsy specimens from 54 normal subjects, 23 men and 31 women, aged 18-90 years. A significant decrease in cortical width and area was seen (P =0.002 and <0.001 respectively), with no difference between sexes. Haversian canal density increased significantly with age by approximately 9% per decade (P = 0.032) but Haversian canal area tended to be lower, resulting in no overall age-related difference in cortical porosity. Haversian canal area was significantly higher in the endosteal section than in the periosteal section of the cortex (P = 0.019) but the Haversian canal density was lower, resulting in similar overall porosity in the two sections. In conclusion, our results demonstrate an age-related decrease in iliac crest cortical width in men and women and an increase in Haversian canal density, but no overall change in cortical porosity.

Effect of vitamin K2 on cortical and cancellous bone mass and hepatic lipids in rats with combined methionine-choline deficiency

The present study examined changes of cancellous and cortical bone in rats with combined methionine–choline deficiency (MCD). In addition, the effects of vitamin K2 on cortical and cancellous bone mass and hepatic lipids were investigated in rats with MCD. Six-week-old male Sprague–Dawley rats were randomized into three groups of ten, including an age-matched control (standard diet) group, an MCD diet group, and an MCD diet + vitamin K2 (menatetrenone at 30 mg/kg/d orally, 5 times a week) group. After the one-month experimental period, histomorphometric analysis was performed on cortical and cancellous bone from the tibial diaphysis and proximal metaphysis, respectively, while histological examination of the liver was performed after staining with hematoxylin and eosin and Oil Red O. MCD rats displayed weight loss, diffuse and centrilobular fatty changes of the liver, and a decrease of the cancellous bone volume per tissue volume (BV/TV) and percent cortical area (Ct Ar) as a result of decreased trabecular, periosteal, and endocortical bone formation along with increased trabecular and endocortical bone resorption. Administration of vitamin K2 to rats with MCD attenuated weight loss, accelerated the decrease of cancellous BV/TV due to an increase of bone remodeling, and ameliorated the decrease of percent Ct Ar by increasing periosteal and endocortical bone formation. Vitamin K2 administration also prevented MCD-induced diffuse fatty change of the liver. These findings suggest a beneficial effect of vitamin K2 on cortical bone mass and hepatic lipid metabolism in rats with MCD. The loss of cancellous bone mass could possibly have been due to re-distribution of minerals to cortical bone.

Relationship between Biochemical Markers and Radial Cortical Bone Changes in Hemodialysis Patients

Background/Aim: Bone loss in patients with osteoporosis may be predicted by the elevation of biochemical markers of bone turnover. Therefore, we studied the relationship between biochemical markers, including parathyroid hormone (PTH), and the 2-year change in radial cortical bone in patients under chronic hemodialysis. Methods: Tartrate-resistant acid phosphatase-5b (TRACP-5b), bone-specific alkaline phosphatase, whole PTH, and total intact PTH were measured in 53 patients under maintenance hemodialysis. Additionally, radial cortical bone mineral density (BMD) and relative cortical area (RCA) were measured by peripheral quantitative computed tomography 2 years apart. Results: In all patients, BMD decreased by 2.5% and RCA decreased by 5.8% during 2 years. TRACP-5b levels significantly correlated with decreased RCA in all and female patients, but not with decreased BMD. Bone-specific alkaline phosphatase correlated with decreased BMD in all patients and with decreased RCA in all and female patients. Whole PTH did not correlate with decreased RCA or BMD. Total intact PTH significantly correlated with decreased BMD in all and male patients and with decreased RCA in all and female patients. In stepwise multiple regression analysis, TRACP-5b and total intact PTH were selected as explanatory variables for decreased RCA and decreased BMD, respectively. Conclusion: These results suggest that TRACP-5b and total intact PTH are powerful markers to predict radial cortical bone loss in hemodialysis patients.

The ovine calcaneus: a useful model for fragility fractures of the hip?

Event Abstract Back to Event The ovine calcaneus: a useful model for fragility fractures of the hip? N Loveridge1*, J Power1, J Reeve1, M Warren2, M Doube3 and A Goodship2 1 University of Cambridge, Orthopaedic Research Unit and Dept of Medicine, United Kingdom 2 Royal Veterinary College, United Kingdom 3 Imperial College, United Kingdom Cases of fragility hip fracture, show excessive loss of cancellous connectivity, cortical thinning and increased porosity. While alterations in mechanical loading are considered to play a key role, currently there is no satisfactory animal model, which mimics the essential biomechanics of the human femoral neck and allows the assessment of both intra-cortical and cancellous bone turnover. The ovine calcaneus is a short bone cantilever loaded in bending with a defined cancellous architecture and cortices that undergo intra-cortical adaptation to habitual tensile and compressive loads. We hypothesised that this bone would respond to decreases in loading with changes in both cancellous and cortical bone so providing an appropriate model to study fragility fractures of the hip. Using external fixators to protect the left calcaneus of ewes (6/group) from normal levels of load related strain we analysed the consequent changes in cortical and cancellous bone after 4, 8 & 16 weeks using the contra-lateral bone as a control.{BR}Fixation reduced maximum local loads by 50% (free: 95.9 microstrain±24.4 (SD); fixed: 48.0±9.9 (SD)) but the marked individual patterning between bones from the same animal was unaffected. Bone volume and BV/TV reduced over time in the left (load protected) but not the right (control) calcaneus (BV: Left -34.72mm3/wk p=0.0002; Right: -4.83mm3/wk, p=0.555 p<0.0001; BV/TV: Left -0.0069/wk; Right: - 4.1522e-5/day, p=0.80). {BR}Trabecular thickness, and number, but not spacing, was affected (Tb.Th: Left -0.133mm/wk, p<0.0001; Right: +0.0084mm/wk, p=0.657; 1/TbN: Left: +0.0133/wk, p<0.0001; Right: +52.87e-5/wk, p=0.75). Both SMI (Left +0.437/wk p<0.0001; Right: -0.11/wk, p=0.339) and aniostropy (Left -0.442/wk p<0.0001; Right: +0.0149mm/wk, p=0.657) were altered by under-loading.{BR}The %cortical area (diff; - 10.6%, p=0.012) and cortical thickness (diff -0.13mm p=0.018) were reduced in the under-loaded calcaneus at 16 weeks. Mean canal area was increased (diff +62.5±15um2; p=0.02) but canals/bone area was unchanged.{BR}In conclusion, under-loading the ovine calcaneus resulted in changes in cancellous and cortical bone, which mimicked most of those seen in fragility fractures of the human femoral neck. This suggests that this model is suitable to further explore hypotheses related to the causes of intracapsular hip fracture and the development of new prevention strategies. Keywords: Bones, Bone Research Conference: 2011 joint meeting of the Bone Research Society & the British Orthopaedic Research Society, Cambridge, United Kingdom, 27 Jun - 29 Jun, 2011. Presentation Type: Poster Topic: Abstracts Citation: Loveridge N, Power J, Reeve J, Warren M, Doube M and Goodship A (2011). The ovine calcaneus: a useful model for fragility fractures of the hip?. Front. Endocrinol. Conference Abstract: 2011 joint meeting of the Bone Research Society & the British Orthopaedic Research Society. doi: 10.3389/conf.fendo.2011.02.00040 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Sep 2011; Published Online: 30 Sep 2011. * Correspondence: Dr. N Loveridge, University of Cambridge, Orthopaedic Research Unit and Dept of Medicine, Cambridge, United Kingdom, nl10003@cam.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers N Loveridge J Power J Reeve M Warren M Doube A Goodship Google N Loveridge J Power J Reeve M Warren M Doube A Goodship Google Scholar N Loveridge J Power J Reeve M Warren M Doube A Goodship PubMed N Loveridge J Power J Reeve M Warren M Doube A Goodship Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Short-term low-strain vibration enhances chemo-transport yet does not stimulate osteogenic gene expression or cortical bone formation in adult mice

Development of low-magnitude mechanical stimulation (LMMS) based treatment strategies for a variety of orthopaedic issues requires better understanding of mechano-transduction and bone adaptation. Our overall goal was to study the tissue and molecular level changes in cortical bone in response to low-strain vibration (LSV: 70 Hz, 0.5 g, 300 με) and compare these to changes in response to a known anabolic stimulus: high-strain compression (HSC: rest inserted loading, 1000 με). Adult (6–7 months) C57BL/6 mice were used for the study and non-invasive axial compression of the tibia was used as a loading model. We first studied bone adaptation at the tibial mid-diaphysis, using dynamic histomorphometry, in response to daily loading of 15 min LSV or 60 cycles HSC for 5 consecutive days. We found that bone formation rate and mineral apposition rate were significantly increased in response to HSC but not LSV. The second aim was to compare chemo-transport in response to 5 min of LSV versus 5 min (30 cycles) of HSC. Chemo-transport increased significantly in response to both loading stimuli, particularly in the medial and the lateral quadrants of the cross section. Finally, we evaluated the expression of genes related to mechano-responsiveness, osteoblast differentiation, and matrix mineralization in tibias subjected to 15 min LSV or 60 cycles HSC for 1 day (4-h time point) or 4 consecutive days (4-day time point). The expression level of most of the genes remained unchanged in response to LSV at both time points. In contrast, the expression level of all the genes changed significantly in response to HSC at the 4-h time point . We conclude that short-term, low-strain vibration results in increased chemo-transport, yet does not stimulate an increase in mechano-responsive or osteogenic gene expression, and cortical bone formation in tibias of adult mice.