Papers by Keyword: Bone Quality

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Authors: Hyung Joon Kim, Seung Moo Han
Abstract: Most ultrasound diagnosing systems for osteoporosis lack diagnostic precision due to the measurement of specific regions of interest (ROI). As well as using the existing ROI measurement method, this study introduced the concept of analyzing the distribution patterns of bone quality. Linear scanning and ultrasound transmission techniques were used to obtain the broadband ultrasound attenuation (BUA) images of the calcaneus. A 13mm-diameter ROI was selected as the position of minimum BUA value locally in the posterior calcaneus. Mean values of BUA and speed of sound (SOS) at the ROI, as well as the osteoporosis index (OI), by their linear combination, were defined. For a more accurate diagnosis of osteoporosis, OI and images of the bone quality distribution of the calcaneus were utilized together. The calcaneus is inhomogeneous and, furthermore, its images are not perpendicular to the direction of the ultrasound beam. Hence, the mean values of BUA and SOS for the entire calcaneus do not have any significant meaning. Accordingly, four image patterns of other OI in the calcaneus were defined in order to increase the correlation between diagnostic parameter and age. The results revealed a higher correlation between the bone quality index and age (r=0.75, p<0.0001), for which the pattern index was reflected on OI, than that (r=0.65, p<0.0001) of OI merely at ROI. This result confirmed the possibility of a new osteoporosis diagnostic method using the BUA distribution images of the entire calcaneus.
Authors: Yun Hua Luo, Hui Juan Yang, Laura Targownik, Andrew Goertzen, William D. Leslie
Abstract: Dual energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) are the two clinic imaging modalities available for examining bone quality. However, there is a dilemma in their selection. DXA uses a lower and safer X-ray dosage, but the produced image is two-dimensional, the information of bone spatial geometry and heterogeneous material distribution required for evaluating bone quality is missing; On the other hand, although QCT is able to capture all the required information, it has to use amuch higher X-ray dosage that may be a potentialhealth concern. Femur cross-section stiffness is an important parameter forassessing bone quality. Although itcan be determined from both DXA and QCT image, it is best computed from QCT for the reason mentioned in the above. In this study, we attempted to establish the ‘equivalence’ between DXA and QCT derived femur cross-section stiffness. If it is successful, DXA can be used in replacement of QCT in assessing bone quality. The study results showed that there indeed exist strong correlations between DXA and QCT derived femur stiffness, but they are not equivalent to each other.
Authors: Ryoichi Suetoshi, Dorian Cretin, Shinji Ogawa, Takayoshi Nakano
Abstract: Following artificial hip joint implantation, a stress inhibition, applied to bone in the surroundings of implants, causes a structural change in bone called bone loss. To evaluate the bone mechanical characteristics, it is essential to investigate the elastic properties of cortical bone. In this article a pair of donor femora was investigated, one with an implant and the other without. Differences in Speed of Sound (SOS), a parameter reflecting elastic properties, were measured in both femora by ultrasound transmission. As a result, in almost all areas, the femur that was implanted showed significantly lower cortical SOS. Our results indicated that the change in the mechanical function of bone, due to the introduction of femoral implants, could be evaluated by the measurement of SOS.
Authors: Jee Wook Lee, Keita Kawahara, Takayoshi Nakano
Abstract: The diagnosis of hard tissues is generally carried out by bone mineral density (BMD) measurement as a bone quantity parameter. BMD, however, does not necessarily explain bone fracture risks in some clinical cases. Recently, various parameters relating to bone strength have been investigated. These additional parameters, so-called bone quality, reflect intrinsic bone conditions. We have been studying the preferential alignment of the biological apatite (BAp) c-axis among various bone quality parameters. BAp, a dominant component of hard tissue, is an ionic crystal that crystallizes in a hexagonal lattice accompanied with the anisotropic property. In this article, we investigated the osteoclast role in the recovery process of BAp orientation during bone regeneration using osteopetrotic (op/op) mice in which the number of osteoclasts decreases. A surgically drilled, 500-μm diameter hole on each tibia of both control and op/op 8-week-old mice was introduced from the medial surface into the medullary cavity located at a 30% length from the proximal tibia end. After surgery, tibiae injuries were regularly observed by in situ micro-CT, and then the mice were sacrificed four to eight weeks after surgery. BAp orientation was analyzed in and near the regenerated portion by the microbeam X-ray diffraction system. As a result, we found the insufficient recovery of BAp orientation in spite of the apparent repair of bone appearance and quantity from CT images, even eight weeks after surgery in both cases of control and op/op mice. We conclude that this defective animal model can be used to evaluate bone quantity and quality at the cortical portion during bone regeneration in gene-defect mice in which the expression of bone cells is controlled, for example.
Authors: Wataru Fujitani, Takayoshi Nakano
Abstract: The orientation of biological apatite (BAp) is one of the bone quality parameters dominating bone mechanical function. In the mandible, the preferential orientation of the BAp c-axis changes depending on alteration of the in vivo stress condition induced by a change in the biting stress. In this study, to clarify the functional adaptation of the preferential BAp orientation and bone mineral density (BMD), all beagle mandibular molars on one side were extracted to remove the biting stress, leading to changes in both BAp orientation and BMD. The BMD exhibited discontinuous distribution around the first molar, mainly responsible for mastication, on the normal side. However, the distribution was continuous along the mesiodistal axis of the edentulous side. The preferential BAp orientation was analyzed in mandibular cross-sections at the first molar root region. Molar extraction led to a change in the BAp orientation: immediately under the root region on the lingual sides, two-dimensional preferential alignment in the mesiodistal and biting directions of the normal side changed to one-dimensional alignment along the mesiodistal axis of the edentulous side. One-dimensional alignment was also observed on the buccal sides irrespective of molar extraction. These findings clarify the close relationship between in vivo biting stress and the preferential BAp orientation, and will be useful clinically for diagnosis, implant placement, and so on.
Authors: Jee Wook Lee, Takayoshi Nakano
Abstract: Measurements of bone mineral density (BMD) cannot accurately predict the risk of bone fracture in some clinical cases; however, BMD is a useful index for assessing the bone condition. Recently, various parameters related to bone strength have been investigated. Among them, we have focused on the preferential orientation of biological apatite (BAp) crystallites analyzed by microbeam-X-ray diffraction, a powerful tool for analyzing BAp crystallites in bones. BAp, a dominant component of bone, is an anisotropic ionic crystal with a hexagonal lattice. In this study, we investigated the mechanism underlying BAp orientation during endochondral or membranous ossification by administering macrophage colony-stimulating factor (M-CSF) to osteopetrotic (op/op) mice lacking M-CSF. op/op mice were treated with intraperitoneal injections of 5 μg recombinant human M-CSF (rhM-CSF); the first injection was administered on the 14th day after birth. In the treated op/op mice, the bone marrow cavities expanded significantly, and this expansion was accompanied by an increase in the number of osteoclasts. Moreover, the degree of BAp orientation along the longitudinal axis was higher in the treated group than in the untreated group. These results suggest that M-CSF is one of the important parameters controlling the preferential alignment of the BAp c-axis.
Authors: Takayoshi Nakano, Aira Matsugaki, Takuya Ishimoto, Mitsuharu Todai, Ai Serizawa, Ryoichi Suetoshi, Yoshihiro Noyama, Wataru Fujitani
Abstract: Bone microstructure is dominantly composed of anisotropic extracellular matrix (ECM) in which collagen fibers and epitaxially-oriented biological apatite (BAp) crystals are preferentially aligned depending on the bone anatomical position, resulting in exerting appropriate mechanical function. The regenerative bone in bony defects is however produced without the preferential alignment of collagen fibers and the c-axis of BAp crystals, and subsequently reproduced to recover toward intact alignment. Thus, it is necessary to produce the anisotropic bone-mimetic tissue for the quick recovery of original bone tissue and the related mechanical ability in the early stage of bone regeneration. Our group is focusing on the methodology for regulating the arrangement of bone cells, the following secretion of collagen and the self-assembled mineralization by oriented BAp crystallites. Cyclic stretching in vitro to bone cells, principal-stress loading in vivo on scaffolds, step formation by slip traces on Ti single crystal, surface modification by laser induced periodic surface structure (LIPSS), anisotropic collagen substrate with the different degree of orientation, etc. can dominate bone cell arrangement and lead to the construction of the oriented ECM similar to the bone tissue architecture. This suggests that stress/strain loading, surface topography and chemical anisotropy are useful to produce bone-like microstructure in order to promote the regeneration of anisotropic bone tissue and to understand the controlling parameters for anisotropic osteogenesis induction.
Authors: Takayoshi Nakano, Takuya Ishimoto, Jee Wook Lee, Sayaka Miyabe, Naoko Ikeo, Hidetsugu Fukuda
Abstract: Our group focused on the preferential degree of biological apatite (BAp) c-axis, an important bone quality parameter based on the microstructural anisotropy in intact, pathological, and regenerated bones. The preferential degree of the BAp c-axis strongly depends on the bone position, in vivo stress distribution, bone growth, degree of pathology and regeneration, activity of bone cells, gene defect, etc. We attempted to challenge clarification of the BAp preferential alignment formation mechanism and control the degree of BAp orientation by using an anisotropic biomaterial design to develop suitable distribution of the BAp c-axis orientation.
Authors: Jee Wook Lee, Takayoshi Nakano, Satoru Toyosawa, Yasuhiko Tabata, Yukichi Umakoshi
Abstract: Bone microstructure and its functions are maintained by the activity of bone cells such as osteoclast for bone resorption and osteoblast for bone formation. In this study, we examined the role of osteoclast on the formation of the preferential orientation of biological apatite (BAp) as a bone quality parameter using OPG-KO and op/op mouse models in which the expression of osteoclast increases for osteoporosis and decreases for osteopetrosis. The orientation degree of the BAp c-axis was analyzed by a microbeam X-ray diffraction system. We found more decrease in the preferential alignment of the BAp c-axis along the longitudinal direction of bone in the femoral bones of both OPG-KO and op/op mice at 12 weeks compared with normal control mice. We concluded that changes in the amount and activity of osteoclast affect BAp alignment, resulting in the degradation of bone microstructure in osteoporosis and osteopetrosis.
Authors: Yoshihiro Noyama, Takuya Ishimoto, Koichi Kuramoto, Takashi Sakai, Hideki Yoshikawa, Takayoshi Nakano
Abstract: The quantity and quality of regenerated bone strongly depends on the direction and amplitude of in vivo principal stress; therefore, in vivo stress distribution near bone implants should be optimized on the basis of the morphology of the interface between an implant and bone tissue. In this study, grooves were created on the implant surface in order to improve the surface morphology of the implant for optimizing in vivo stress distribution near the implant. The preferential alignment of the biological apatite (BAp) c-axis, which is a parameter of bone quality and controls the mechanical function of bones, is closely related to stress distribution; therefore, the direction of principal stress should be matched with the direction of the groove on the implant surface. Hip implants were prepared with grooves aligned at different angles from the surface; the grooves were located on the stem portion. These implants were inserted in a beagle femur to investigate the dependency of the quantity and quality of newly formed bone in the grooves on the groove angle. The degree of preferential alignment of the BAp c-axis of the regenerated bone in the grooves strongly depends on the angle of the groove to the principal stress vector that was estimated previously to an animal experiment. The regenerated bone forms anisotropic BAp orientation in response to the principal stress in the grooves; therefore, the direction of the grooves has to be designed on the basis of the stress distribution near the implant.
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