Femoral Head Trabecular Bone Research Articles

Trabecular, but not cortical, bone tissue protein synthesis rates are lower in the femoral head when compared to the proximal femur following an intracapsular hip fracture.

All musculoskeletal tissues are in a constant state of turnover, with a dynamic equilibrium between tissue protein synthesis and breakdown rates. The synthesis of protein allows musculoskeletal tissues to heal following injury. Yet, impaired tissue healing is observed following certain injuries, such as geriatric hip fractures. It is assumed that the regenerative properties of femoral head bone tissue are compromised following an intracapsular hip fracture and therefore hip replacement surgery is normally performed. However, the actual impact on in vivo bone protein synthesis rates has never been determined. In the present study, 10 patients (age: 79±10 y, BMI: 24±4kg/m2) with an acute (<24h) intracapsular hip fracture received a primed continuous intravenous infusion of L-[ring-13C6]-phenylalanine before and throughout their hip replacement surgery. Trabecular and cortical bone tissue from both the femoral head and proximal femur were sampled during surgery to assess protein synthesis rates of affected (femoral head) and unaffected (proximal femur) bone tissue, respectively. In addition, tissue samples of gluteus maximus muscle, synovium, ligamentum teres, and femoral head cartilage were collected. Tissue-specific protein synthesis rates were assessed by measuring L-[ring-13C6]-phenylalanine incorporation in tissue protein. Femoral head trabecular bone protein synthesis rates (0.056 [0.024-0.086] %/h) were lower when compared to proximal femur trabecular bone protein synthesis rates (0.081 [0.056-0.118] %/h; P=0.043). Cortical bone protein synthesis rates did not differ between the femoral head and proximal femur (0.041 [0.021-0.078] and 0.045 [0.028-0.073] %/h, respectively; P>0.05). Skeletal muscle, synovium, ligamentum teres, and femoral head cartilage protein synthesis rates averaged 0.080 [0.048-0.089], 0.093 [0.051-0.130], 0.121 [0.110-0.167], and 0.023 [0.015-0.039] %/h, respectively. In contrast to the general assumption that the femoral head is avital after an intracapsular displaced hip fracture in the elderly, our data show that bone protein synthesis is still ongoing in femoral head bone tissue during the early stages following an intracapsular hip fracture in older patients. Nonetheless, trabecular bone protein synthesis rates are lower in the femoral head when compared to the proximal femur in older patients following an acute intracapsular hip fracture. Trial register no: NL9036.

The osteogenic commitment of CD271+CD56+ bone marrow stromal cells (BMSCs) in osteoarthritic femoral head bone

Osteoarthritis (OA), the most common joint disorder, is characterised by progressive structural changes in both the cartilage and the underlying subchondral bone. In late disease stages, subchondral bone sclerosis has been linked to heightened osteogenic commitment of bone marrow stromal cells (BMSCs). This study utilised cell sorting and immunohistochemistry to identify a phenotypically-distinct, osteogenically-committed BMSC subset in human OA trabecular bone. Femoral head trabecular bone tissue digests were sorted into CD45-CD271+CD56+CD146-, CD45-CD271+CD56-CD146+ and CD45-CD271+CD56-CD146-(termed double-negative, DN) subsets, and CD45+CD271-hematopoietic-lineage cells served as control. Compared to the CD146+ subset, the CD56+ subset possessed a lower-level expression of adipocyte-associated genes and significantly over 100-fold higher-level expression of many osteoblast-related genes including osteopontin and osteocalcin, whilst the DN subset presented a transcriptionally ‘intermediate’ BMSC population. All subsets were tri-potential following culture-expansion and were present in control non-OA trabecular bone. However, while in non-OA bone CD56+ cells only localised on the bone surface, in OA bone they were additionally present in the areas of new bone formation rich in osteoblasts and newly-embedded osteocytes. In summary, this study reveals a distinct osteogenically-committed CD271+CD56+ BMSC subset and implicates it in subchondral bone sclerosis in hip OA. CD271+CD56+ subset may represent a future therapeutic target for OA and other bone-associated pathologies.

Human-like hip joint loading in Australopithecus africanus and Paranthropus robustus

Adaptations indicative of habitual bipedalism are present in the earliest recognized hominins. However, debate persists about various aspects of bipedal locomotor behavior in fossil hominins, including the nature of gait kinematics, locomotor variability across different species, and the degree to which various australopith species engaged in arboreal behaviors. In this study, we analyze variation in trabecular bone structure of the femoral head using a sample of modern humans, extant non-human hominoids, baboons, and fossil hominins attributed to Australopithecus africanus, Paranthropus robustus, and the genus Homo. We use μCT data to characterize the fabric anisotropy, material orientation, and bone volume fraction of trabecular bone to reconstruct hip joint loading conditions in these fossil hominins. Femoral head trabecular bone fabric structure in australopiths is more similar to that of modern humans and Pleistocene Homo than extant apes, indicating that these australopith individuals walked with human-like hip kinematics, including a more limited range of habitual hip joint postures (e.g., a more extended hip) during bipedalism. Our results also indicate that australopiths have robust femoral head trabecular bone, suggesting overall increased loading of the musculoskeletal system comparable to that imposed by extant apes. These results provide new evidence of human-like bipedal locomotion in Pliocene hominins, even while other aspects of their musculoskeletal systems retain ape-like characteristics.

Age-Related Changes in Femoral Head Trabecular Microarchitecture.

Osteoporosis is a prevalent bone condition, characterised by low bone mineral density and increased fracture risk. Currently, the gold standard for identifying osteoporosis and increased fracture risk is through quantification of bone mineral density using dual energy X-ray absorption. However, many studies have shown that bone strength, and consequently the probability of fracture, is a combination of both bone mass and bone ‘quality’ (architecture and material chemistry). Although the microarchitecture of both non-fracture and osteoporotic bone has been previously investigated, many of the osteoporotic studies are constrained by factors such as limited sample number, use of ovariectomised animal models, and lack of male and female discrimination. This study reports significant differences in bone quality with respect to the microarchitecture between fractured and non-fractured human femur specimens. Micro-computed tomography was utilised to investigate the microarchitecture of femoral head trabecular bone from a relatively large cohort of non-fracture and fracture human donors. Various microarchitectural parameters have been determined for both groups, providing an understanding of the differences between fracture and non -fracture material. The microarchitecture of non-fracture and fracture bone tissue is shown to be significantly different for many parameters. Differences between sexes also exist, suggesting differences in remodelling between males and females in the fracture group. The results from this study will, in the future, be applied to develop a fracture model which encompasses bone density, architecture and material chemical properties for both female and male tissues.

Estimating the density of femoral head trabecular bone from hip fracture patients using computed tomography scan data.

The purpose of this study was to compare computed tomography density (ρCT ) obtained using typical clinical computed tomography scan parameters to ash density (ρash ), for the prediction of densities of femoral head trabecular bone from hip fracture patients. An experimental study was conducted to investigate the relationships between ρash and ρCT and between each of these densities and ρbulk and ρdry . Seven human femoral heads from hip fracture patients were computed tomography-scanned ex vivo, and 76 cylindrical trabecular bone specimens were collected. Computed tomography density was computed from computed tomography images by using a calibration Hounsfield units-based equation, whereas ρbulk, ρdry and ρash were determined experimentally. A large variation was found in the mean Hounsfield units of the bone cores (HUcore) with a constant bias from ρCT to ρash of 42.5 mg/cm3. Computed tomography and ash densities were linearly correlated (R 2 = 0.55, p < 0.001). It was demonstrated that ρash provided a good estimate of ρbulk (R 2 = 0.78, p < 0.001) and is a strong predictor of ρdry (R 2 = 0.99, p < 0.001). In addition, the ρCT was linearly related to ρbulk (R 2 = 0.43, p < 0.001) and ρdry (R 2 = 0.56, p < 0.001). In conclusion, mineral density was an appropriate predictor of ρbulk and ρdry , and ρCT was not a surrogate for ρash . There were linear relationships between ρCT and physical densities; however, following the experimental protocols of this study to determine ρCT , considerable scatter was present in the ρCT relationships.

A Method for the Evaluation of Femoral Head Trabecular Bone Compressive Properties

We addressed the importance of defining a mechanical testing methodology for the compression of human trabecular bone specimens. In fact, currently there are several protocols to test trabecular bone, but a single, standard and validate method has not been accepted yet. In our work, human femoral epiphyses collected from patients with osteoporosis (fragility fractures) and hip osteoarthritis, submitted to total hip replacement surgery, were used. The aims of our work were to develop a mechanical testing methodology for the compression of trabecular bone specimens taking into account the optimization of bone extrinsic and intrinsic variables, in order to establish a patient bone sample database with clinical, structural and mechanical information. Extrinsic variables, such as the effect of specimen preparation, with particular focus on the dimensions of test specimens, and others associated with the compression test, such as the method employed to determine specimen deformation, and hence strain, were evaluated. Also, a new device used to withhold the specimens was developed and tested by the present authors. Although each specimen showed a unique behaviour, even when comparing compression curves between patients from the same disease group, implicating additional complexity and difficulty in the data analysis, the authors managed to assemble the results in two groups related with a possible difference in the deformation mechanisms occurring after yielding.

Does skeletal anatomy reflect adaptation to locomotor patterns? cortical and trabecular architecture in human and nonhuman anthropoids

Although the correspondence between habitual activity and diaphyseal cortical bone morphology has been demonstrated for the fore- and hind-limb long bones of primates, the relationship between trabecular bone architecture and locomotor behavior is less certain. If sub-articular trabecular and diaphyseal cortical bone morphology reflects locomotor patterns, this correspondence would be a valuable tool with which to interpret morphological variation in the skeletal and fossil record. To assess this relationship, high-resolution computed tomography images from both the humeral and femoral head and midshaft of 112 individuals from eight anthropoid genera (Alouatta, Homo, Macaca, Pan, Papio, Pongo, Trachypithecus, and Symphalangus) were analyzed. Within-bone (sub-articular trabeculae vs. mid-diaphysis), between-bone (forelimb vs. hind limb), and among-taxa relative distributions (femoral:humeral) were compared. Three conclusions are evident: (1) Correlations exists between humeral head sub-articular trabecular bone architecture and mid-humerus diaphyseal bone properties; this was not the case in the femur. (2) In contrast to comparisons of inter-limb diaphyseal bone robusticity, among all species femoral head trabecular bone architecture is significantly more substantial (i.e., higher values for mechanically relevant trabecular bone architectural features) than humeral head trabecular bone architecture. (3) Interspecific comparisons of femoral morphology relative to humeral morphology reveal an osteological "locomotor signal" indicative of differential use of the forelimb and hind limb within mid-diaphysis cortical bone geometry, but not within sub-articular trabecular bone architecture.

Trabecular bone structure in the humeral and femoral heads of anthropoid primates

Studies of anthropoid femoral head trabecular bone structure have found broad similarity across taxonomic and locomotor groups. The goal of this study is to assess the effects of differential limb usage on the trabecular bone architecture of the femur and humerus across taxa with diverse locomotor behaviors. High‐resolution computed tomography scans were collected from the proximal humerus and femur of 55 individuals from five anthropoid species including S. syndactylus, Papio sp., P. rubicunda, A. caraya, and P. troglodytes. Trabecular structural features including bone volume fraction, anisotropy, trabecular thickness, and trabecular number were quantified in volumes positioned in the center of each joint. Femoral head bone volume is consistently higher than humeral bone volume in all taxa independent of locomotor behavior. Humeral trabecular bone is more isotropic than femoral trabecular bone in all species sampled, possibly reflecting the emphasis on a mobile shoulder joint and manipulative forelimb. The results indicate broad similarity in bone structure across all anthropoids. Supported by NSF BCS‐0617097.

Trabecular Bone Structure in the Humeral and Femoral Heads of Anthropoid Primates

The functional significance of three-dimensional trabecular bone architecture in the primate postcranial skeleton has received significant interest over the last decade. Some previous work has produced promising results, finding significant relationships between femoral head trabecular bone structure and hypothesized locomotor loading in leaping and nonleaping strepsirrhines. Conversely, most studies of anthropoid femoral head bone structure have found broad similarity across taxonomic and locomotor groups. The goal of this study is to expand on past analyses of anthropoid trabecular bone structure by assessing the effects of differential limb usage on the trabecular bone architecture of the forelimb and hindlimb across taxa characterized by diverse locomotor behaviors, including brachiation, quadrupedalism, and climbing. High-resolution x-ray computed tomography scans were collected from the proximal humerus and proximal femur of 55 individuals from five anthropoid primate species, including Symphalangus syndactylus, Papio sp., Presbytis rubicunda, Alouatta caraya, and Pan troglodytes. Trabecular bone structural features including bone volume fraction, anisotropy, trabecular thickness, and trabecular number were quantified in large volumes positioned in the center of the humeral or femoral head. Femoral head trabecular bone volume is consistently and significantly higher than trabecular bone volume in the humerus in all taxa independent of locomotor behavior. Humeral trabecular bone is more isotropic than femoral trabecular bone in all species sampled, possibly reflecting the emphasis on a mobile shoulder joint and manipulative forelimb. The results indicate broad similarity in trabecular bone structure in these bones across anthropoids.

Vergleichende Stabilitätsuntersuchungen an DHS- und DHN-Osteosynthesen subkapitaler Pauwels-III-Osteotomien als Modell höhergradig instabiler medialer Schenkelhalsfrakturen

High failure rates due to instability and redisplacement are reported using the dynamic hip screw-fixation of femoral neck fractures in the elderly. This fact was the reason for the development of the dynamic hip nail (DHN) which has a TU cross-section profile and should provide more resistance against cutting through the femoral head trabecular bone than the commonly used DHS. For a comparing stability investigation fixation of vertical femoral neck osteotomies in eight pairs of macroscopically normal cadaver femora was performed with either the DHS supplemented proximally with a parallel 6.5 mm cancellous screw or the DHN. Fixed in a testing machine at an adduction angle of 9° the specimens were vertically loaded from 1 kN up to 4.5 kN with a stepwise increase of 0.5 kN and 500 load cycles within each load level. The applied loads were increased until a distal displacement of the femoral heads of 2 mm was measured. From the recorded loads and number of cycles at the 2 mm distal head displacement the overall load bearing capacity of the DHS- and DHN-osteosyntheses were calculated in kN. The test results indicated that the DHN provided a much more stronger support for the femoral head against dynamic vertical compression loads than the DHS. In three of the eight DHN-osteosyntheses the 2 mm distal head displacement did not occur after 500 cycles at the maximal load of 4.5 kN. The mean overall load bearing capacity of the DHS-osteosyntheses at the 2 mm distal head displacement was 4301,4 kN and that of the DHN-osteosyntheses was 8332,3 kN. Especially in the pairs of femora with weak bone the DHN provided a much more higher resistance against cutting through than the DHS. From the biomechanical standpoint the results indicate that the DHN seems to be a more saver device for the fixation of femoral neck fractures than the DHS.

Mechanical properties of femoral trabecular bone in dogs

BackgroundStudying mechanical properties of canine trabecular bone is important for a better understanding of fracture mechanics or bone disorders and is also needed for numerical simulation of canine femora. No detailed data about elastic moduli and degrees of anisotropy of canine femoral trabecular bone has been published so far, hence the purpose of this study was to measure the elastic modulus of trabecular bone in canine femoral heads by ultrasound testing and to assess whether assuming isotropy of the cancellous bone in femoral heads in dogs is a valid simplification.MethodsFrom 8 euthanized dogs, both femora were obtained and cubic specimens were cut from the centre of the femoral head which were oriented along the main pressure and tension trajectories. The specimens were tested using a 100 MHz ultrasound transducer in all three orthogonal directions. The directional elastic moduli of trabecular bone tissue and degrees of anisotropy were calculated.ResultsThe elastic modulus along principal bone trajectories was found to be 11.2 GPa ± 0.4, 10.5 ± 2.1 GPa and 10.5 ± 1.8 GPa, respectively. The mean density of the specimens was 1.40 ± 0.09 g/cm3. The degrees of anisotropy revealed a significant inverse relationship with specimen densities. No significant differences were found between the elastic moduli in x, y and z directions, suggesting an effective isotropy of trabecular bone tissue in canine femoral heads.DiscussionThis study presents detailed data about elastic moduli of trabecular bone tissue obtained from canine femoral heads. Limitations of the study are the relatively small number of animals investigated and the measurement of whole specimen densities instead of trabecular bone densities which might lead to an underestimation of Young's moduli. Publications on elastic moduli of trabecular bone tissue present results that are similar to our data.ConclusionThis study provides data about directional elastic moduli and degrees of anisotropy of canine femoral head trabecular bone and might be useful for biomechanical modeling of proximal canine femora.

Evaluation of the material property of the bone

Strength of bone is determined by the volume, the structure and the quality of the bone. Microdamage can be detected in bone by bulk stain method, which is one of the major determinant of the bone fatigue. Microdamages are accumulated in the femoral head trabecular bone of aged subjects and femoral neck fracture patients. Microdamage is repaired in vivo by bone remodeling.

The three-dimensional structure of trabecular bone in the femoral head of strepsirrhine primates

It has been hypothesized for over a hundred years that trabecular bone plays an important structural role in the musculoskeletal system of animals and that it responds dynamically to applied loads through growth. The objectives of this study are to quantify the three-dimensional structure of femoral head trabecular bone in a sample of extant strepsirrhines and to relate patterns of interspecific variation to locomotor behavioral differences. The bone volume fraction (BV/TV) and fabric anisotropy of trabecular bone in the femoral heads of Cheirogaleus major, Avahi laniger, Galago senegalensis, Galago alleni, Loris tardigradus, Otolemur crassicaudatus, and Perodicticus potto were quantified in three dimensions using serial high-resolution X-ray computed tomography scan data. A volume based method was used to quantify the structural anisotropy in three cubic samples located inside the central portion of the femoral head. Significant structural differences were found between the predominantly leaping galagines and indriids and the nonleaping lorisines and cheirogaleids. The leapers in general have relatively anisotropic trabecular bone. The galagines display a unique pattern of decreasing bone volume and increasing anisotropy moving from the superior to the inferior half of the femoral head. By contrast, the nonleaping taxa possess relatively uniform and isotropic bone throughout the femoral head. The differences in femoral head trabecular structure among these taxa seem to be related to locomotor behavioral differences, reflecting variation in the use and loading of the hip joint during normal locomotion.

Characterization of tissue transglutaminase in human osteoblast-like cells.

Tissue transglutaminase (tTG) is a calcium-dependent and guanosine 5'-triphosphate (GTP) binding enzyme, which catalyzes the post-translational modification of proteins by forming intermolecular epsilon(gamma-glutamyl)lysine cross-links. In this study, human osteoblasts (HOBs) isolated from femoral head trabecular bone and two osteosarcoma cell lines (HOS and MG-63) were studied for their expression and localization of tTG. Quantitative evaluation of transglutaminase (TG) activity determined using the [1,4 14C]-putrescine incorporation assay showed that the enzyme was active in all cell types. However, there was a significantly higher activity in the cell homogenates of MG-63 cells as compared with HOB and HOS cells (p < 0.001). There was no significant difference between the activity of the enzyme in HOB and HOS cells. All three cell types also have a small amount of active TG on their surface as determined by the incorporation of biotinylated cadaverine into fibronectin. Cell surface-related tTG was further shown by preincubation of cells with tTG antibody, which led to inhibition of cell attachment. Western blot analysis clearly indicated that the active TG was tTG and immunocytochemistry showed it be situated in the cytosol of the cells. In situ extracellular enzyme activity also was shown by the cell-mediated incorporation of fluorescein cadaverine into extracellular matrix (ECM) proteins. These results clearly showed that MG-63 cells have high extracellular activity, which colocalized with the ECM protein fibronectin and could be inhibited by the competitive primary amine substrate putrescine. The contribution of tTG to cell surface/matrix interactions and to the stabilization of the ECM of osteoblast cells therefore could by an important factor in the cascade of events leading to bone differentiation and mineralization.

Mitogenic responsiveness of human bone cells in vitro to hormones and growth factors decreases with age.

Bone loss with aging may at least in part be due to inadequate bone formation. In this study, we examined whether the proliferation of osteoblast-like cells in vitro in response to local and systemic factors might be attenuated with age. A total of 36 cultures of osteoblast-like cells were obtained from outgrowths of human trabecular bone. Parathyroid hormone, growth hormone, calcitonin, transforming growth factor beta, insulin-like growth factor I, and platelet-derived growth factor BB dose dependently increased DNA synthesis in all cultures. Increases in DNA synthesis with each of these factors were significantly negatively correlated with donor age in cultures obtained from the iliac crest bone of 50- to 70-year-old women. Cells from 61- to 70-year-old donors required approximately 10-fold higher concentrations of growth factors and hormones to yield comparable increases in DNA synthesis than cells from 51- to 60-year-old donors. A significant negative correlation between age and mitogenic responsiveness to platelet-derived growth factor and growth hormone, but not toward the other factors, was also observed in cultures from the femoral head trabecular bone of 60- to 90-year-old women. Our findings suggest that bone loss with aging may be partially due to a decreased capacity of osteoblasts to proliferate in response to systemic or locally released osteotropic factors.

Bone growth and development in prehistoric populations from Sudanese Nubia

The analysis of a large sample of skeletons from a number of Sudanese Nubian cemeteries demonstrates the usefulness of this material in the study of bone growth and development. A skeletal series from the Meroitic (B.C. 350-A.D. 350), X-Group (A.D. 350–550), and Christian (A.D. 550–1400) period were utilized in determining the rate of bone development and age related changes in the internal structure of the femur. Specifically, we have been able to demonstrate the following: 1.(i) The growth velocity determined from the long bones in the Nubian sample was similar but somewhat more irregular than the growth velocity of long bones in American boys studied longitudinally.2.(2) Growth symmetry of long bones determined by the ratio of lengths shows a greater stability than that which occurs in American boys.3.(3) Decrease in femoral cortical thickness with age was significant in Nubian females (P < 0·001), while the decrease in males was not significant. The loss of cortical bone tissue in Nubian females appears to begin earlier than similar changes in modern females.4.(4) The density of femoral head trabecular bone organ volume decreases with age at similar rates in both males and females, but the females lose a larger percentage of density since they enter the age period (17 years) with a lower density.5.(5) The average thickness of femoral head trabeculae decrease with age in males, while in females there is an increase in thickness. It appears that as cross-members decrease in thickness with age, struts increase in thickness.6.(6) Microradiographic analysis of archeological material may provide an additional dimension to the study of bone turnover rates.