Trabecular Features Research Articles

Anticipating bipedalism: trabecular organization in the newborn ilium.

Trabecular bone structural organization is considered to be predominantly influenced by localized temporal forces which act to maintain and remodel the trabecular architecture into a biomechanically optimal configuration. In the adult pelvis, the most significant remodelling forces are believed to be those generated during bipedal locomotion. However, during the fetal and neonatal period the pelvic complex is non-weight bearing and, as such, structural organization of iliac trabecular bone cannot reflect direct stance-related forces. In this study, micro-computed tomography scans from 28 neonatal ilia were analysed, using a whole bone approach, to investigate the trabecular characteristics present within specific volumes of interest relevant to density gradients highlighted in a previous radiographic study. Analysis of the structural indices bone volume fraction, trabecular thickness, trabecular spacing and trabecular number was carried out to quantitatively investigate structural composition. Quantification of the neonatal trabecular structure reinforced radiographic observations by highlighting regions of significant architectural form which grossly parallel architectural differences in the adult pattern but which have previously been attributed to stance-related forces. It is suggested that the seemingly organized rudimentary scaffold observed in the neonatal ilium may be attributable to other non-weight bearing anatomical interactions or even to a predetermined genetic blueprint. It must also be postulated that whilst the observed patterning may be indicative of a predetermined inherent template, early non-weight bearing and late stance-related locomotive influences may subsequently be superimposed upon this scaffolding and perhaps reinforced and likely remodelled at a later age. Ultimately, the analysis of this fundamental primary pattern has core implications for understanding the earliest changes in pelvic trabecular architecture and provides a baseline insight into future ontogenetic development and bipedal capabilities.

New bone formation by murine osteoprogenitor cells cultured on corticocancellous allograft bone

The gold standard for bone grafting in orthopedics is autograft, however autograft has a limited supply and is associated with significant morbidity at the harvest site. One alternative, allograft bone, provides an osteoconductive scaffold, is in less limited supply, and it does not require a harvest from the patient. However, allograft lacks both osteogenic cells and osteoinductive proteins that make autograft bone so advantageous. This study provides a model to investigate strategies for augmentation of corticocancellous allograft bone discs with bone marrow-derived osteoprogenitor cells (OPCs) plus exogenous growth factors in vitro. In this model, allograft bone discs were created by cutting 1-mm thick slices from the distal femur and proximal tibia of euthanized mice. The allografts were sterilized and scanned by micro-computed tomography (microCT) to provide the pre-culture graft volume and trabecular characteristics. The discs were then seeded with OPCs harvested from murine bone marrow. The seeded grafts were placed in organ culture until harvest, after which they were re-scanned by microCT and the data compared to the corresponding pre-culture data. In addition, bone morphogenetic protein-7 (BMP-7, also know as osteogenic protein-1 or OP-1), basic fibroblast growth factor (bFGF), and OP-1 combined with bFGF were added on a daily basis to the cultures. After final microCT scanning, all grafts were sectioned and evaluated histologically after hematoxylin and eosin (H&E) staining. microCT scans of cultured allografts with cells at 3, 5, and 9 weeks showed a time-dependent, statistically significant increase in bone volume. The trabecular thickness (Tb.Th.) of grafts, from both groups that were augmented with OP-1, showed a statistically significant increase in trabecular thickness of allografts with OPCs. These data suggest that bone marrow-derived OPCs adhere to, and produce, new bone on corticocancellous allograft in vitro. When exogenous OP-1 is added to this model, an increase in the production of bone onto the corticocancellous allograft bone disc is seen. This model allows for the investigation of the effects of multiple growth factors, and other interventions, on OPCs seeded onto allograft bone in vitro.

Correlations between grey-level variations in 2D projection images (TBS) and 3D microarchitecture: Applications in the study of human trabecular bone microarchitecture

X-ray imaging remains a very cost-effective technique, with many applications in both medical and material science. However, the physical process of X-ray imaging transforms (e.g. projects) the 3-dimensional (3D) microarchitecture of the object or tissue being studied into a complex 2D grey-level texture. The 3D/2D projection process continues to be a difficult mathematical problem, and neither demonstrations nor well-established correlations have positioned 2D texture analysis-based measurement as a valid indirect evaluation of 3D microarchitecture. The trabecular bone score (TBS) is a new grey-level texture measurement which utilizes experimental variograms of 2D projection images. The aim of the present study was to determine the level of correlation between the 3D characteristics of trabecular bone microarchitecture, as evaluated using µCT reconstruction, and TBS, as evaluated using 2D projection images derived directly from 3D µCT reconstruction. Analyses were performed using sets of human cadaver bone samples from different anatomical sites (lumbar spine, femoral neck, and distal radius). Significant correlations were established via standard multiple regression analysis, and via the use of a generic mathematical 3D/2D relationship. In both instances, the correlations established a significant relationship between TBS and two 3D characteristics of bone microarchitecture: bone volume fraction and mean bone thickness. In particular, it appears that TBS permits to accurately differentiate between two 3D microarchitectures that exhibit the same amount of bone, but different trabecular characteristics. These results demonstrate the existence of a robust and generic relationship, taking into consideration a simplified model of a 2D projection image. Ultimately, this may lead to using TBS measurements directly on DXA images obtained in routine clinical practice.

Ab interno trabeculectomy: Ultrastructural evidence and early tissue response in a human eye

To report the results of ultrastructural analysis of the postoperative effects of ab interno trabeculectomy in a human eye. Department of Ophthalmology, Palmanova Hospital, Palmanova, Udine, Italy. A 60-year-old woman with cataract and glaucoma had enucleation for a choroidal melanoma 10 days after ab interno trabeculectomy combined with phacoemulsification. A second ab interno trabeculectomy was performed after enucleation to evaluate the outcomes of the previous trabeculectomy. Light and transmission electron microscopy analyses were performed on samples excised from areas (1) not subjected to a procedure (control samples), (2) that had ab interno trabeculectomy before enucleation, and (3) that had ab interno trabeculectomy immediately after enucleation. Control samples showed normal trabecular features. Semithin sections of all ab interno trabeculectomy samples showed full-thickness removal of trabeculum segments, with Schlemm's canal lumen opening into the anterior chamber and apparent preservation of the adjacent structures. On ultrathin sections of samples that had ab interno trabeculectomy before enucleation, the endothelium lining the outer wall of Schlemm's canal and other angle components showed intact ultrastructural features. In trabecular beams that were not removed, the extracellular matrix appeared to have maintained its fine texture and was free of activated fibroblasts or leucocyte infiltrates. Observations confirm that ab interno trabeculectomy causes direct communication between Schlemm's canal lumen and the anterior chamber in vivo and immediately after enucleation during the early postoperative period. The absence of an evident inflammatory reaction in the examined case should be considered with caution because of possible tumor-induced immune suppression.

Bone microarchitecture in males with corticosteroid-induced osteoporosis

Microarchitectural changes in trabecular bone were analyzed by microcomputed tomography (microCT) and histomorphometry in 24 patients with corticosteroid-induced osteoporosis. The microCT images revealed a reduction in trabecular thickness only on frequency distribution curves, with no increase in trabecular separation. Trabecular plate thinning and perforations were easily identified. Corticosteroid-induced osteoporosis (CSIOP) is mediated by direct actions of the drug on bone cells. The result is a decrease in trabecular bone mass and a reduction in trabecular thickness, but connectivity is believed to remain rather well preserved. Twenty-four transiliac bone biopsies from patients with CSIOP were studied conjointly by histomorphometry [with two-dimensional (2D) architectural descriptors] and microCT (with 3D analysis of trabecular characteristics, including trabecular thickness and separation). The frequency distribution of thickness and separation were compared with data obtained in nine control subjects. 2D histomorphometry revealed a decrease in bone volume and trabecular thickness in the bone biopsies of the CSIOP patients when compared to those of the controls. MicroCT appeared to be able to identify the reduction in thickness only when the frequency distribution of trabecular thickness was computed. No difference for the curves of the frequency distribution of trabecular separation was evidenced between patients and controls. MicroCT and 2D histomorphometric results were correlated, but 2D analysis appeared to be more sensitive. However, microCT identified a very specific thinning of the trabecular plates in their center that corresponds to the earlier stages of perforations. Trabecular plate thinning can be observed and perforations occur on very thin plates in CSIOP patients.

Morphological analysis of periapical radiographs in the mandible may identify women with low skeletal bone mineral density

Article Title and Bibliographic Information Age and trabecular features of alveolar bone associated with osteoporosis. Lee BD, White SC. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100(1):92-8. Level of Evidence 4 Purpose/Question The purpose of this study was to determine if a combination of trabecular pattern, alveolar bone density, and clinical parameters is associated with a subject's femoral/lumbar World Health Organization (WHO) bone mineral density class. Source of Funding USPHS research grant R01 AR47529 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health (NIH) Type of Study/Design Case-control study

Texture analysis of X-ray radiographs of iliac bone is correlated with bone micro-CT

Alteration of bone trabecular architecture is a predictor of fracture risk in osteoporosis. Until now, microarchitecture can only be measured on a bone biopsy, thus limiting microarchitecture analysis in routine clinical practice for osteoporosis. Texture analysis on X-ray images has been advocated to be a suitable means to assess two-dimensional (2-D) microarchitecture in the research field. But little is known about the relationships between three-dimensional (3-D) architecture and texture analysis, particularly in clinical practice. The purposes of the study were: (1) to explore the relationship between 3-D histomorphometric parameters and 2-D texture analysis, and (2) to see if cortical assessment may influence results. In this study, the anterosuperior part of the iliac bone was removed from 24 cadavers. Large samples were prepared and comprised of the crest and a strip of bone approximately 3 cm wide and 5 cm long. These large specimens were used in order to preserve bone architecture; they also corresponded to the location used by histomorphometrists for the diagnosis of metabolic bone diseases on iliac crest biopsies. Bone samples were examined with a microcomputed tomograph for 3-D microarchitecture [BV/TV, C.BV/C.TV, Tb.P(f), structure model index (SMI), Tb.Th, Tb.N, Tb.Sp]. Texture analysis was done by several methods (skeletonization, run lengths, fractal techniques) from X-ray projection images. No correlation was found between bone mass parameters (BV/TV and C.BV/C.TV, which take into account both cortical and trabecular bone) and texture parameters. However, when specific descriptors of trabecular bone microarchitecture were used, several relationships with texture parameters were found [(Tb.N)/BOUND, r=0.628;/VGLN, r=0.596;/Fractal D, r=0.569]. When multiple correlations were used, the correlation coefficients were markedly improved with trabecular characteristics. X-ray texture analysis seemed to be a suitable approach for 2-D bone microarchitecture assessment. Furthermore, there is a good correlation between texture analysis of X-ray radiographs and 3-D bone microarchitecture assessed by microcomputed tomography.

Comparison Insight Bone Measurements by Histomorphometry and μCT

Morphometric analysis of 70 bone biopsies was done in parallel by microCT and histomorphometry. microCT provided higher results for trabecular thickness and separation because of the 3D shape of these anatomical objects. Bone histomorphometry is used to explore the various metabolic bone diseases. The technique is done on microscopic 2D sections, and several methods have been proposed to extrapolate 2D measurements to the 3D dimension. X-ray microCT is a recently developed imaging tool to appreciate 3D architecture. Recently the use of 2D histomorphometric measurements have been shown to provide discordant results compared with 3D values obtained directly. Seventy human bone biopsies were removed from patients presenting with metabolic bone diseases. Complete bone biopsies were examined by microCT. Bone volume (BV/TV), Tb.Th, and Tb.Sp were measured on the 3D models. Tb.Th and Tb.Sp were measured by a method based on the sphere algorithm. In addition, six images were resliced and transferred to an image analyzer: bone volume and trabecular characteristics were measured after thresholding of the images. Bone cores were embedded undecalcified; histological sections were prepared and measured by routine histomorphometric methods providing another set of values for bone volume and trabecular characteristics. Comparison between the different methods was done by using regression analysis, Bland-Altman, Passing-Bablock, and Mountain plots. Correlations between all parameters were highly significant, but microCT overestimated bone volume. The osteoid volume had no influence in this series. Overestimation may have been caused by a double threshold used in microCT, giving trabecular boundaries less well defined than on histological sections. Correlations between Tb.Th and Tb.Sp values obtained by 3D or 2D measurements were lower, and 3D analysis always overestimated thickness by approximately 50%. These increases could be attributed to the 3D shape of the object because the number of nodes and the size of the marrow cavities were correlated with 3D values. In clinical practice, microCT seems to be an interesting method providing reliable morphometric results in less time than conventional histomorphometry. The correlation coefficient is not sufficient to study the agreement between techniques in histomorphometry. The architectural descriptors are influenced by the algorithms used in 3D.

A precise receptor-positioning device for subtraction radiography, based on cross-arch stabilization

To devise and test for reproducibility a new patient-beam alignment device for subtraction radiography. A rigid, cross-arch bar was used with bite-registration material. A modified Rinn XCP rod and ring were firmly attached to the bar and were placed in contact with the X-ray cone. The receptor was held by a slot in the bar. Duplicate sets (n=8 pairs) of digital radiographs were made with a modified, calibrated DenOptix photostimulable phosphor system. Image pairs were registered and compared for geometrical and intensity errors by means of quantitative subtraction radiography. The reproducibility of patient-beam alignment for each pair was determined by measuring spatial errors at alveolar crest edges and by comparing magnifications. Intensity errors measured at two predetermined regions of alveolar bone were used to estimate corresponding bone-mass errors. Misalignment at the alveolar crest was generally <1 pixel (0.085 mm), and everywhere < or =0.25 mm. The magnification was constant within a relative standard deviation of 0.13% (n=8). Trabecular features were generally invisible or barely visible in subtraction images. The standard deviation of intensity errors was 1.07% (n=16). This corresponds to a change in bone mass of approximately 2% or less. The device has potential for clinical population studies in which the goal is to detect small changes in bone mass and alveolar-crest height. It is convenient to use and comfortable for patients. Because of the cross-arch design, patient-beam alignment is expected to be relatively insensitive to bite-registration errors, tooth movement, and tooth loss.

Change in mandibular trabecular pattern and hip fracture rate in elderly women

To determine if alterations of trabecular pattern, or the rate of change of jaw trabeculae, are associated with rate of hip fracture. Participants in a population-based study of residents of a California retirement community (Leisure World Cohort Study) were asked for permission to obtain their dental radiographs. Periapical radiographs were retrieved on 598 women (average age at time of first radiograph=77 years). Several measurements of trabecular pattern (strut analysis), textural properties (run-length analysis) and Fourier analysis were made in several anatomical regions of the jaw. These trabecular features and clinical information self-reported by subjects in the early 1980s were examined for association with hip fracture rate using Cox proportional-hazard regression. Rate of hip fracture increased with decreasing average length of node-to-terminus struts in the mandibular incisor region. Each 0.01 mm per year decrease in the average length of node-to-terminus struts increased hip fracture rate by a factor of 2.9 (P=0.02, accuracy=73%). Inclusion of clinical parameters improved the predictive model compared with use of the radiographic parameter alone (accuracy=79%). Similar results were seen for percent change per year in this parameter. Changes in radiographic trabecular structure, augmented with clinical information, are predictive of hip fracture in elderly women. Further refinement of both the radiographic and clinical parameters may lead to a screening process accessible to a large number of women and to early diagnosis and treatment of osteoporosis.

Age and trabecular features of alveolar bone associated with osteoporosis

To determine the utility of clinical features, combined with optical density measurements and morphologic analysis of periapical images, for identifying individuals with low lumbar or femoral bone mineral density. Study subjects consisted of 37 females and 29 males. Bone mineral densities (BMD) of lumbar spine and proximal femur were measured by dual-energy x-ray absorptiometry. Clinical variables included subjects' age, height, and weight. Optical density and morphologic features were measured from subjects' posterior maxilla and mandible. Classification and regression tree analysis was used to assess agreement between actual and predicted BMD status. The combination of clinical and morphological analysis of trabecular pattern are associated with femoral/lumbar BMD. Significant associations were found in the maxilla and mandible. The most important clinical variable was age. This study showed that morphologic analysis of periapical radiographs, combined with clinical variables, can assist in identifying individuals with low femoral/lumbar BMD.

Texture analysis of X-ray radiographs is correlated with bone histomorphometry

Three-dimensional (3D) alteration of trabecular microarchitecture is a risk factor for vertebral fractures. Histomorphometry allows microarchitectural analysis of bone, but the necessity to perform a transiliac bone biopsy limits its use in large series of patients. X-Ray films are commonly used in routine practice and constitute a 2D projection of the trabecular architecture. In this study, blocks of trabecular dried bone were prepared from calf bone. They were selected from different parts of the femoral condyle to provide various patterns of trabecular disposition. All blocks (25 x 15 x 8 mm) were radiographed on a numeric X-ray system, with the same acquisition parameters. Texture analysis was carried out by several methods: (skeletonization, run lengths, and fractal techniques). Histological sections of the blocks were obtained and analyzed by 2D histomorphometric methods: trabecular bone volume (BV/TV), trabecular characteristics, and 2D descriptors of architecture (star volumes, strut analysis, fractal dimensions). Significant correlations were obtained for BV/TV with run length parameters measured on the X-ray image. The trabecular characteristics were found to be highly correlated with texture parameters describing the X-ray image (e.g., trabecular number [Tb.N]/axis, r = -0.82;/short run emphasis [SRE], r = -0.87; trabecular separation [Tb.Sp]/gray level nonuniformity [GLN], r = -0.82). Several histomorphometric parameters, independent of the "plate-and-rod" model, were also well correlated with texture descriptors. Although the relationships between the 2D and 3D trabecular architecture are not fully elucidated, the texture analysis of X-ray films might be a suitable approach to investigate the disorganization of bone in osteoporosis.

Clinical and panoramic predictors of femur bone mineral density

Dentists are a potentially valuable resource for initial patient screening for signs of osteoporosis, as individuals with osteoporosis have altered architecture of the inferior border of the mandible as seen on panoramic radiographs. Our aim was to evaluate the efficacy of combining clinical and dental panoramic radiographic risk factors for identifying individuals with low femoral bone mass. Bone mineral density was measured at the femoral neck and classified as normal, osteopenic or osteoporotic using WHO criteria in 227 Japanese postmenopausal women (33-84 years). Panoramic radiographs were made of all subjects. Mandibular cortical shape and width was determined and trabecular features were measured in each ramus. Mean subject age, height, and weight were significantly different in the three bone-density groups (P<0.0001). A classification and regression trees (CART) analysis using just clinical risk factors identified 136 (87%) of the 157 individuals with femoral osteopenia or osteoporosis. Mean mandible cortical width (P<0.0001), cortical index (P<0.0001) and trabecular features (P=0.02) were also significantly different in the three bone density groups. A CART analysis considering only radiographic features found 130 (83%) of the 157 individuals with femoral osteopenia or osteoporosis, although none of the subjects with osteoporosis was correctly identified. A CART analysis using both clinical and radiographic features found that the most useful risk factors were thickness of inferior border of the mandible and age. This algorithm identified 130 (83%) of the 157 individuals with femoral osteopenia or osteoporosis. The results of this study suggest that 1) clinical information is as useful as panoramic radiographic information for identifying subjects having low bone mass, and 2) dentists have sufficient clinical and radiographic information to play a useful role in screening for individuals with osteoporosis.

Comparison of histomorphometric descriptors of bone architecture with dual-energy X-ray absorptiometry for assessing bone loss in the orchidectomized rat.

We have compared different methods for measuring bone loss in the orchidectomized (ORX) rat model of male osteoporosis: densitometry (DXA), ash weight, anatomic bone indices, histomorphometry and two-dimensional trabecular architecture analysis. Forty-eight male Wistar rats were studied at 2, 4, 8 and 16 weeks (four groups). In each group, 6 rats were ORX and 6 sham-operated were used as control. DXA was performed on the whole body, tibia and femur. Histomorphometry was performed on the secondary spongiosa of the tibia: trabecular bone volume (BV/TV) and trabecular characteristics (number, separation and thickness) were measured. Architecture analysis comprised strut identification, star volume of the marrow spaces and trabeculae, Euler-Poincaré number (E) and Kolmogorov fractal dimension (Dk). Bone mineral densities of the whole body, tibia and femur were reduced at 16 weeks in the ORX group. BV/TV was significantly decreased in the ORX group from the fourth week. Differences in the sensitivity of the architectural methods were found. There were no differences in trabecular thickness nor in trabecular star volume between ORX and controls even after 16 weeks. E became different at 8 weeks. Trabecular number, node count, star volume of the marrow spaces and trabecular separation became significantly different at 4 weeks Dk was modified after 2 weeks (p < 0.05 at 2 weeks, p < 0.001 from 4 weeks). In the ORX model, Dk appeared the most potent descriptor of trabecular bone disorganization by revealing the earliest changes at the network level.

Oreopithecus was a bipedal ape after all: evidence from the iliac cancellous architecture.

Textural properties and functional morphology of the hip bone cancellous network of Oreopithecus bambolii, a 9- to 7-million-year-old Late Miocene hominoid from Italy, provide insights into the postural and locomotor behavior of this fossil ape. Digital image processing of calibrated hip bone radiographs reveals the occurrence of trabecular features, which, in humans and fossil hominids, are related to vertical support of the body weight, i.e., to bipedality.