Changes In Trabecular Structure Research Articles

Characterization of knee osteoarthritis-related changes in trabecular bone using texture parameters at various levels of spatial resolution-a simulation study.

Articular cartilage and subchondral bone are the key tissues in osteoarthritis (OA). The role of the cancellous bone increasingly attracts attention in OA research. Because of its fast adaptation to changes in the loading distribution across joints, its quantification is expected to improve the diagnosis and monitoring of OA. In this study, we simulated OA progression-related changes of trabecular structure in a series of digital bone models and then characterized the potential of texture parameters and bone mineral density (BMD) as surrogate measures to quantify trabecular bone structure. Five texture parameters were studied: entropy, global and local inhomogeneity, anisotropy and variogram slope. Their dependence on OA relevant structural changes was investigated for three spatial resolutions typically used in micro computed tomography (CT; 10 μm), high-resolution peripheral quantitative CT (HR-pQCT) (90 μm) and clinical whole-body CT equipment (250 μm). At all resolutions, OA-related changes in trabecular bone architecture can be quantified using a specific (resolution dependent) combination of three texture parameters. BMD alone is inadequate for this purpose but if available reduces the required texture parameter combination to anisotropy and global inhomogeneity. The results are summarized in a comprehensive analysis guide for the detection of structural changes in OA knees. In conclusion, texture parameters can be used to characterize trabecular bone architecture even at spatial resolutions below the dimensions of a single trabecula and are essential for a detailed classification of relevant OA changes that cannot be achieved with a measurement of BMD alone.

Occlusal load distribution through the cortical and trabecular bone of the human mid-facial skeleton in natural dentition: A three-dimensional finite element study

Understanding of the occlusal load distribution through the mid-facial skeleton in natural dentition is essential because alterations in magnitude and/or direction of occlusal forces may cause remarkable changes in cortical and trabecular bone structure. Previous analyses by strain gauge technique, photoelastic and, more recently, finite element (FE) methods provided no direct evidence for occlusal load distribution through the cortical and trabecular bone compartments individually. Therefore, we developed an improved three-dimensional FE model of the human skull in order to clarify the distribution of occlusal forces through the cortical and trabecular bone during habitual masticatory activities. Particular focus was placed on the load transfer through the anterior and posterior maxilla. The results were presented in von Mises stress (VMS) and the maximum principal stress, and compared to the reported FE and strain gauge data. Our qualitative stress analysis indicates that occlusal forces distribute through the mid-facial skeleton along five vertical and two horizontal buttresses. We demonstrated that cortical bone has a priority in the transfer of occlusal load in the anterior maxilla, whereas both cortical and trabecular bone in the posterior maxilla are equally involved in performing this task. Observed site dependence of the occlusal load distribution may help clinicians in creating strategies for implantology and orthodontic treatments. Additionally, the magnitude of VMS in our model was significantly lower in comparison to previous FE models composed only of cortical bone. This finding suggests that both cortical and trabecular bone should be modeled whenever stress will be quantitatively analyzed.

Early Changes of Trabecular Bone Structure in Asymptomatic Subjects With Knee Malalignment

To investigate whether alterations of trabecular bone structure can already be found in young asymptomatic subjects with knee malalignment. Forty-eight subjects with neutral, mild varus, severe varus, and valgus knee joint alignment were included in this study (12 subjects in each group). Histomorphometric and texture parameters of the trabecular bone in the medial/lateral femur/tibia were determined using 1.5-T magnetic resonance imaging. Apparent trabecular thickness in the medial tibia compartment was lower in the valgus group (mean ± standard error, 0.353 ± 0.012 mm) compared with the neutral (0.396 ± 0.011 mm; P = 0.043), mild varus (0.403 ± 0.011 mm; P = 0.038) and severe varus groups (0.416 ± 0.013 mm; P = 0.015). In the medial femur compartment, fractal dimension was significantly greater in the mild (1.697 ± 0.005; P = 0.015) and severe varus groups (1.698 ± 0.005; P = 0.036) than in the valgus group (1.674 ± 0.005). The observed findings may be signs of the adaptation of the subchondral bone to altered loading conditions and possibly of early knee joint impairment.

The effects of Labisia pumila on postmenopausal osteoporotic rat model: Dose and time-dependent micro-CT analysis.

Postmenopausal osteoporosis is best treated and prevented by estrogen replacement therapy (ERT). Although effective, ERT may cause breast cancer, uterine cancer and cardiovascular problems. Labisia pumila var. alata (LP), a herb with phytoestrogenic, antioxidative and anti-inflammatory effects has potential as an ERT alternative. This study aimed to evaluate micro-CT analysis on the effects of LP supplementation on the trabecular microarchitecture of postmenopausal osteoporosis rat model. Micro-CT is an effective tool in detecting changes in trabecular bone structure and providing a three dimensional information which may replace other conventional bone analysis methods. Ninety-six female Sprague-Dawley rats (4 to 5 months old) were randomly divided into six groups of baseline group (BL) Sham-operated (Sham), ovariectomised control (OVXC), ovariectomised with 64.5 μg/kg of Premarin (ERT), ovariectomised with 20 mg/kg of LP (LP20) and ovariectomised with 100 mg/kg of LP at (LP100). The vehicle (deionized water), Premarin and LP were given via daily oral gavages for three, six and nine weeks of treatment periods. Rats in BL group were euthanized before the start of the study, while other rats were euthanized after completion of their treatments. Femora were dissected out and trabecular bone microarchitecture analysed with micro-CT. Micro-CT analysis of OVXC rats revealed significant osteoporotic changes in connectivity density, trabecular bone volume, trabecular thickness, trabecular separation and trabecular number. Both ERT and LP were able to reverse all the OVX-induced bone changes with the best results seen with 100 mg/kg of LP for nine weeks duration of treatment. Micro-CT provides accurate and reliable information on trabecular bone parameters which aid in the diagnosis and treatment of osteoporosis. LP supplementation at 100 mg/kg was more effective than ERT in reversing ovariectomy-induced bone changes. Further studies are required to explore the potential of LP as ERT alternative in the treatment and prevention of postmenopausal osteoporosis.

Trabecular bone structure correlates with hand posture and use in hominoids.

Bone is capable of adapting during life in response to stress. Therefore, variation in locomotor and manipulative behaviours across extant hominoids may be reflected in differences in trabecular bone structure. The hand is a promising region for trabecular analysis, as it is the direct contact between the individual and the environment and joint positions at peak loading vary amongst extant hominoids. Building upon traditional volume of interest-based analyses, we apply a whole-epiphysis analytical approach using high-resolution microtomographic scans of the hominoid third metacarpal to investigate whether trabecular structure reflects differences in hand posture and loading in knuckle-walking (Gorilla, Pan), suspensory (Pongo, Hylobates and Symphalangus) and manipulative (Homo) taxa. Additionally, a comparative phylogenetic method was used to analyse rates of evolutionary changes in trabecular parameters. Results demonstrate that trabecular bone volume distribution and regions of greatest stiffness (i.e., Young's modulus) correspond with predicted loading of the hand in each behavioural category. In suspensory and manipulative taxa, regions of high bone volume and greatest stiffness are concentrated on the palmar or distopalmar regions of the metacarpal head, whereas knuckle-walking taxa show greater bone volume and stiffness throughout the head, and particularly in the dorsal region; patterns that correspond with the highest predicted joint reaction forces. Trabecular structure in knuckle-walking taxa is characterised by high bone volume fraction and a high degree of anisotropy in contrast to the suspensory brachiators. Humans, in which the hand is used primarily for manipulation, have a low bone volume fraction and a variable degree of anisotropy. Finally, when trabecular parameters are mapped onto a molecular-based phylogeny, we show that the rates of change in trabecular structure vary across the hominoid clade. Our results support a link between inferred behaviour and trabecular structure in extant hominoids that can be informative for reconstructing behaviour in fossil primates.

Augmented mandibular bone structurally adapts to functional loading

Long-term changes in trabecular bone structure during the 10 years following onlay grafting with simultaneous mandibular implant placement were studied. Extraoral radiographs of both mandibular sides in eight patients were taken regularly. Bone structure was analysed using a custom-written image analysis program. Parameters studied were trabecular area and perimeter and marrow cavity area and perimeter. After skeletonisation of the trabecular network, the number of end points and branching points, skeleton length, and branch angle were determined. The observed structural changes agree with the development of a more complex and more delicate or fine osseous structure. The bone shows more trabecular branching. All changes are most pronounced in the graft spongiosa, but are also found in the graft cortex and in the original mandible. The mean trabecular branch angle becomes more horizontal. The applied technique can be used to analyse long-term changes in the architecture of bone grafts. Changes found in the graft architecture correspond to changes expected after functional adaptation to loading.

The vertebrae of prematurely aging mice as a skeletal model of involutional osteoporosis.

Oxidative stress in bone increases with age, which leads to bone frailty and a high fracture risk. Animal models show that early changes in trabecular structure occur in age-related osteopenia. These models might be valuable to assess the contribution of oxidative stress in age-related bone loss. Premature aging mice (PAM) have previously been characterized as a model of premature immunological and neurological senescence. PAM long bones (mainly consisting of cortical bone) display features of aging bone. Thus, we aimed to evaluate the vertebrae, representing a unique poorly loaded type of trabecular bone in mice, in PAM and no PAM (NPAM) controls. PAM showed an anxious behaviour, based on physical activity evaluation. These mice had decreased bone mineral density (0.078 mg/cm² in NPAM vs 0.070 g/cm² in PAM; p⟨0.05); a decreased number of osteocytes per bone field (404±36 in NPAM vs 320±27 in PAM; p⟨0.01); and downregulation of various osteoblastic genes and low eroded surface/bone surface, 4.2±0.5 in NPAM vs 1.9±0.2 in PAM; p⟨0.01). This was associated with increased expression of oxidative stress markers, Foxo1 and GADD45, in PAM vertebrae. Mesenchymal progenitors in the bone marrow of PAM have a poor mineralization capacity (assessed by the number of mineralized nodules and suface), and showed a lower response to an osteogenic input -represented by parathormone-related protein-, compared to NPAM. Collectively, these results indicate that PAM vertebrae show osteopenia related to diminished bone formation and remodeling. Our findings further support the validity of PAM as a suitable model for involutional osteoporosis and its treatment.

Impaired bone formation and osteopenia in heterozygous βIVSII-654 knockin thalassemic mice

β-thalassemia caused by the C→T mutation at nucleotide 654 of the intron 2 (β(IVSII-654)) results in aberrant splicing of β-globin RNA, leading to an almost absence of β-globin synthesis. Although trabecular and cortical bone loss was previously reported in β-thalassemic mice with deletion of β-globin gene, the microscopic changes in trabecular structure in β(IVSII-654) thalassemic mice remained elusive. Here, we investigated the macroscopic and microscopic bone changes in 12-week-old β(IVSII-654) knockin thalassemic mice by dual-energy X-ray absorptiometry (DXA) and histomorphometric analysis, respectively. DXA revealed a decrease in bone mineral density in the lumbar vertebrae and tibial metaphysis, but not in the femoral diaphysis, suggesting that β(IVSII-654) thalassemia predominantly led to osteopenia at the trabecular site, but not the cortical site. Further histomorphometric analysis of the tibial secondary spongiosa showed that trabecular bone volume was significantly decreased with the expansion of marrow cavity. Decreases in osteoblast surface, osteoid surface, mineral apposition rate, mineralizing surface, and mineralized volume were also observed. Moreover, trabecular bone resorption was markedly enhanced as indicated by increases in the osteoclast surface and eroded surface. It could be concluded that β(IVSII-654) thalassemia impaired bone formation and enhanced bone resorption, thereby leading to osteopenia especially at the trabecular sites, such as the tibial metaphysis.

Levels of serotonin, sclerostin, bone turnover markers as well as bone density and microarchitecture in patients with high-bone-mass phenotype due to a mutation in Lrp5

Patients with an activation mutation of the Lrp5 gene exhibit high bone mass (HBM). Limited information is available regarding compartment-specific changes in bone. The relationship between the phenotype and serum serotonin is not well documented. To evaluate bone, serotonin, and bone turnover markers (BTM) in Lrp5-HBM patients, we studied 19 Lrp5-HBM patients (T253I) and 19 age- and sex-matched controls. DXA and HR-pQCT were used to assess BMD and bone structure. Serum serotonin, sclerostin, dickkopf-related protein 1 (DKK1), and BTM were evaluated. Z-scores for the forearm, total hip, lumbar spine, forearm, and whole body were significantly increased (mean ± SD) between 4.94 ± 1.45 and 7.52 ± 1.99 in cases versus -0.19 ± 1.19 to 0.58 ± 0.84 in controls. Tibial and radial cortical areas, thicknesses, and BMD were significantly higher in cases. In cases, BMD at the lumbar spine and forearm and cortical thickness were positively associated and trabecular area negatively associated with age (r = 0.49, 0.57, 0.74, and -0.61, respectively, p < .05). Serotonin was lowest in cases (69.5 [29.9-110.4] ng/mL versus 119.4 [62.3-231.0] ng/mL, p < .001) and inversely associated with tibial cortical density (r = -0.49, p < .05) and directly with osteocalcin (OC), bone-specific alkaline phosphatase (B-ALP), and procollagen type 1 amino-terminal propeptide (PINP) (r = 0.52-0.65, p < .05) in controls only. OC and S-CTX were lower and sclerostin higher in cases, whereas B-ALP, PINP, tartrate-resistant acid phosphatase (TRAP), and dickkopf-related protein 1 (DKK1) were similar in cases and controls. In conclusion, increased bone mass in Lrp5-HBM patients seems to be caused primarily by changes in trabecular and cortical bone mass and structure. The phenotype appeared to progress with age, but BTM did not suggest increased bone formation.

Prediction of Biomechanical Properties of Trabecular Bone in MR Images With Geometric Features and Support Vector Regression

Whole knee joint MR image datasets were used to compare the performance of geometric trabecular bone features and advanced machine learning techniques in predicting biomechanical strength properties measured on the corresponding ex vivo specimens. Changes of trabecular bone structure throughout the proximal tibia are indicative of several musculoskeletal disorders involving changes in the bone quality and the surrounding soft tissue. Recent studies have shown that MR imaging also allows non-invasive 3-D characterization of bone microstructure. Sophisticated features like the scaling index method (SIM) can estimate local structural and geometric properties of the trabecular bone and may improve the ability of MR imaging to determine local bone quality in vivo. A set of 67 bone cubes was extracted from knee specimens and their biomechanical strength estimated by the yield stress (YS) [in MPa] was determined through mechanical testing. The regional apparent bone volume fraction (BVF) and SIM derived features were calculated for each bone cube. A linear multiregression analysis (MultiReg) and a optimized support vector regression (SVR) algorithm were used to predict the YS from the image features. The prediction accuracy was measured by the root mean square error (RMSE) for each image feature on independent test sets. The best prediction result with the lowest prediction error of RMSE = 1.021 MPa was obtained with a combination of BVF and SIM features and by using SVR. The prediction accuracy with only SIM features and SVR (RMSE = 1.023 MPa) was still significantly better than BVF alone and MultiReg (RMSE = 1.073 MPa). The current study demonstrates that the combination of sophisticated bone structure features and supervised learning techniques can improve MR-based determination of trabecular bone quality.

Osteoporotic changes of subchondral trabecular bone in osteoarthritis of the knee: a 3-T MRI study

Subchondral trabecular bone structure was analyzed in knee osteoarthritis (OA) patients using 3-T MRI to investigate structural features of subchondral trabecular bone of knee OA. With OA progression, osteoporotic changes were observed in the lateral joint, showing a higher correlation than sclerotic changes in the medial joint. To investigate structural features of subchondral trabecular bone of knee osteoarthritis (OA). Sixty knees with KL grade 0-4 (all female) were examined. Fast imaging employing steady-state acquisition-cycled phases (FIESTA-c) and FatSat Spoiled gradient recalled acquisition in the steady state (SPGR) images were acquired by 3-T MRI. At four sites (the medial femur, medial tibia, lateral femur, and lateral tibia), subchondral trabecular bone structure was analyzed by FIESTA-c imaging, cartilage area was measured by SPGR imaging, and their correlation was analyzed. In addition, the subjects were classified into four groups from the cartilage area measured by SPGR imaging, and subchondral trabecular bone structure in each group was compared. As cartilage area decreased in the medial joint, bone volume fraction and trabecular thickness in the medial tibia increased, and bone volume fraction, trabecular thickness, number, and connectivity in the lateral femur and lateral tibia decreased (r ≥ 0.4 or ≤-0.4, p ≤ 0.001). Compared to medially, the changes laterally showed a higher correlation. When the medial-lateral ratio of trabecular thickness in the tibia was determined, it had the highest correlation coefficient (r=-0.7, p < 0.001). These changes were not significantly detected in the early stage. To more sensitively detect OA changes in subchondral trabecular bone structure, a focus on osteoporotic changes in the lateral joint and the medial-lateral ratio would be useful. Detectability of early OA remains unknown, but based on a strong correlation with the degree of OA progression, trabecular structural analysis of subchondral bone may be a useful parameter to evaluate OA severity and evaluate treatment.

Bone Structure Changes in Iliac Crest Grafts Combined with Implants

Remodeling of onlay grafts combined with implants to the mandible results in predictable changes in the graft's radiographic density. We studied the relationship between changes in radiographic density and trabecular structure during the first year after onlay grafting with simultaneous implant placement to the mandible. The aim of this study was to evaluate changes in bone structure after onlay grafting. Standardized extraoral radiographs were taken regularly of 16 mandibular sides. Bone structure was measured using the Carl Zeiss Vision KS 400 3.0 imaging system. The parameters studied were trabecular area and perimeter, cavity area and perimeter, end points, branching points, skeleton length, branch angle and direction, and texture. No differences were found between measurements ventrally versus dorsally of the implant, nor close to versus away from the implant. Early cortical changes suggest partial resorption and formation of a more complex structure. In the fourth quarter after surgery, progressive resorption is seen in the graft's upper cortex. In the graft's upper spongiosa, most parameters indicate bone formation during the first postoperative year. Loading-induced structure changes could not yet be found. The technique can be used to study changes in the architecture of bone grafts. Changes found in the graft's architecture are in accordance with changes in bone density.

Lymphangioma Mimicking Apical Periodontitis

Introduction Lymphangiomas mimicking apical periodontitis, usually found in soft tissue of children and infants younger than 2 years, are extremely rare in aged patients, particularly in bone tissues. Methods An 81-year-old woman was seen in a radiological service to undergo imaging studies for the placement of dental implants. A panoramic radiograph showed a radiolucent multilocular structure in the left mandibular molar region, where teeth #17 and #18 had previously been treated endodontically. A fracture in tooth #17 was detected. Because of the patient’s clinical history and the characteristics of the image, which showed changes in trabecular bone structure, the patient was referred for cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI) for further evaluation. CBCT scans demonstrated a well-circumscribed lesion immediately below the roots of teeth #17 and #18. MRI showed no involvement of the surrounding soft tissues, and the lesion affected only the mandibular bone. Incision biopsy was performed, and the tissue sample (histopathology specimen) was sent to microscopic evaluation. Results Microscopically, there was a proliferation of vascular endothelium covered by long and mature endothelial cells. In the vessel lumens, there was eosinophilic material similar to lymph. The microscopic examination suggested the diagnosis of lymphangioma. Conclusions Pathologies of non-endodontic origin such as lymphangioma, which might be in the area of the tooth apex, should be included in the differential diagnosis of apical periodontitis. Histopathologic examination is mandatory for their diagnosis and treatment.

Changes of trabecular bone structure in rats with sciatic nerve denervation

Changes of trabecular bone structure in rats with sciatic nerve denervation

In early OA, thinning of the subchondral plate is directly related to cartilage damage: results from a canine ACLT-meniscectomy model

The pathogenesis of osteoarthritis (OA) includes cartilage degeneration, synovial inflammation, and bone changes. Slowly, the sequence and inter-relationship of these features is becoming clearer. Early models of OA suggest thinning of the subchondral plate in addition to trabecular bone changes. In the present study subchondral bone changes were studied in the canine anterior cruciate ligament transection (ACLT)-meniscectomy model. This model is characterized by intra-joint variability with respect to cartilage damage (predominantly medial) and loading (lateral unloading due to a shifted axis). In 13 Labrador dogs, OA was induced by transection of the anterior cruciate ligament and removal of the medial meniscus. Twelve weeks later, cartilage integrity was evaluated histologically using the modified Mankin score (0-11), and proteoglycan content was determined by Alcian Blue assay. Bone architecture of the tibia was quantified by micro-CT. Cartilage damage was severe in the medial compartment (Mankin score +3.5, glycosaminoglycan (GAG) content -28%) and mild in the lateral compartment (Mankin score +1.6, GAG content -15%). Thinning and porosity of the subchondral plate were only present on the medial side (-21%, +87%, respectively). Interestingly, changes in trabecular bone structure did almost not occur in the medial compartment (volume fraction -7%) but were clear in the lateral compartment (-20%). Thinning of the subchondral plate is a localized phenomenon related to cartilage degeneration while trabecular bone changes are related to mechanical (un)loading. The different mechanisms responsible for bone changes in OA should be taken in account when designing and interpreting studies interfering with bone turnover in the treatment of OA.

Computational Study on Trabecular Bone Remodeling in Human Femur under Reduced Weight-bearing Conditions

Trabecular bone structure is determined by a balance between osteoblastic bone formation and osteoclastic bone resorption, which is regulated partly by osteocytes according to their mechanical environments. There have been a number of studies on bone remodeling in response to mechanical stimuli, mainly in the physiological range. This study uses a mathematical model previously formulated for surface remodeling available even for disuse and overuse ranges considering osteocyte apoptosis and targeted remodeling. Thus, the present model allows exhibiting the changes of trabecular bone structure under, below, and beyond the daily loading condition. In this study, we carried out computer simulation of bone remodeling in human femur under normal daily loading condition and reduced weight-bearing conditions (infrequent and cane-assisted walking conditions). Decreased trabecular bone with reducing loading condition was shown, and the trabecular bone structure at various degrees of disuse was consistent to Singh Index for osteoporosis diagnosis.

Increased bone resorption and osteopenia in Dlx5 heterozygous mice

Distal-less (Dlx) homeobox transcription factors play a central role in the control of osteogenesis. In particular, Dlx5 regulates osteoblasts/osteoclasts coupling during perinatal bone formation. We analyze here the effect of Dlx5 allelic reduction in the control of bone remodeling. We first show that Dlx5 expression persists during postnatal bone development. We then compare the skeletal phenotype of 10- and 20-week-old Dlx5(+/-) mice to that of wild-type (WT) littermates. Dlx5(+/-) male mice exhibit lower bone mineral density (BMD) at both ages while only 20-week-old females are affected. microCT analyses reveal a reduction in cortical thickness of femoral midshafts in Dlx5(+/-) mice. Histomorphometry on distal femora shows no changes in trabecular structure and confirms a reduction in Dlx5(+/-) cortical thickness. The cortical decrease of 10-week-old mice does not derive from a reduction in periosteal bone apposition, but results from increased bone resorption with a significantly higher number of endosteal osteoclasts per bone surface and a larger marrow diameter. Urinary level of deoxypyridinoline is also higher in heterozygous mice confirming an increase in bone resorption activity. Our findings might be relevant for understanding complex, multifactorial diseases such as osteoporosis in which quantitative deregulation of gene expression leads to disruption of bone homeostasis.

Computer simulation of trabecular remodeling in human proximal femur using large-scale voxel FE models: Approach to understanding Wolff's law

Ever since Julius Wolff proposed the law of bone transformation in the 19th century, it has been widely known that the trabecular structure of cancellous bone adapts functionally to the loading environment. To understand the mechanism of Wolff's law, a three-dimensional (3D) computer simulation of trabecular structural changes due to surface remodeling was performed for a human proximal femur. A large-scale voxel finite element model was constructed to simulate the structural changes of individual trabeculae over the entire cancellous region. As a simple remodeling model that considers bone cellular activities regulated by the local mechanical environment, nonuniformity of local stress was assumed to drive the trabecular surface remodeling to seek a uniform stress state. Simulation results demonstrated that cell-scale (∼10 μm) remodeling in response to mechanical stimulation created complex 3D trabecular structures of the entire bone-scale (∼10 cm), as illustrated in the reference of Wolff. The bone remodeling reproduced the characteristic anisotropic structure in the coronal cross section and the isotropic structures in other cross sections. The principal values and axes of a structure characterized by fabric ellipsoids corresponded to those of the apparent stress of the structure. The proposed large-scale computer simulation indicates that in a complex mechanical environment of a hierarchical bone structure of over 10 4 length scale (from ∼10 μm to ∼10 cm), a simple remodeling at the cellular/trabecular levels creates a highly complex and functional trabecular structure, as characterized by bone density and orientation.

Numerical simulation on the adaptation of forms in trabecular bone to mechanical disuse and basic multi-cellular unit activation threshold at menopause

The objective of this paper is to identify the effects of mechanical disuse and basic multi-cellular unit (BMU) activation threshold on the form of trabecular bone during menopause. A bone adaptation model with mechanical- biological factors at BMU level was integrated with finite element analysis to simulate the changes of trabecular bone structure during menopause. Mechanical disuse and changes in the BMU activation threshold were applied to the model for the period from 4 years before to 4 years after menopause. The changes in bone volume fraction, trabecular thickness and fractal dimension of the trabecular structures were used to quantify the changes of trabecular bone in three different cases associated with mechanical disuse and BMU activation threshold. It was found that the changes in the simulated bone volume fraction were highly correlated and consistent with clinical data, and that the trabecular thickness reduced significantly during menopause and was highly linearly correlated with the bone volume fraction, and that the change trend of fractal dimension of the simulated trabecular structure was in correspondence with clinical observations. The numerical simulation in this paper may help to better understand the relationship between the bone morphology and the mechanical, as well as biological environment; and can provide a quantitative computational model and methodology for the numerical simulation of the bone structural morphological changes caused by the mechanical environment, and/or the biological environment.

Temporal radiographic texture analysis in the detection of periprosthetic osteolysis

Periprosthetic osteolysis is one of the most serious long-term problems in total hip arthroplasty. It has been primarily attributed to the body's inflammatory response to submicron polyethylene particles worn from the hip implant, and it leads to bone loss and structural deterioration in the surrounding bone. It was previously demonstrated that radiographic texture analysis (RTA) has the ability to distinguish between osteolysis and normal cases at the time of clinical detection of the disease; however, that analysis did not take into account the changes in texture over time. The goal of this preliminary analysis, however, is to assess the ability of temporal radiographic texture analysis (tRTA) to distinguish between patients who develop osteolysis and normal cases. Two tRTA methods were used in the study: the RTA feature change from baseline at various follow-up intervals and the slope of the best-fit line to the RTA data series. These tRTA methods included Fourier-based and fractal-based features calculated from digitized images of 202 total hip replacement cases, including 70 that developed osteolysis. Results show that separation between the osteolysis and normal groups increased over time for the feature difference method, as the disease progressed, with area under the curve (AUC) values from receiver operating characteristic analysis of 0.65 to 0.72 at 15 years postsurgery. Separation for the slope method was also evident, with AUC values ranging from 0.65 to 0.76 for the task of distinguishing between osteolysis and normal cases. The results suggest that tRTA methods have the ability to measure changes in trabecular structure, and may be useful in the early detection of periprosthetic osteolysis.