ABSTRACT
BACKGROUND:The lower cervical vertebral pedicle is the main stress site of the posterior column of the spine,which is of great significance for the maintenance of the stability of the human center of gravity and the reduction of shock.At present,there are few reports on the characteristics of the internal bone trabeculae,and the characteristics of the joint site of the vertebral pedicle with the articular process and the vertebral body.It is urgent to understand the fine anatomical structure of the vertebral pedicle and the relationship and function of each part. OBJECTIVE:To observe the microanatomical morphology of the vertebral pedicle by Micro-CT scanning of cervical vertebra specimens,and to measure and analyze the microstructure and morphometric parameters of the bone trabecula in the cervical pedicle under normal conditions to evaluate the safety performance of the cervical spine. METHODS:Micro-CT scanning was performed on 31 sets of cervical vertebrae C3-C7.By checking and reconstructing the areas of interest in the bone trabecular within the vertebral pedicle,the morphological characteristics and distribution direction of the bone trabecular within the cervical pedicle were observed,and the bone microstructure parameters were detected,and the differences in the bone microstructure of the C3-C7 vertebral pedicle were analyzed and compared. RESULTS AND CONCLUSION:(1)The Micro-CT images showed that the honeycomb bone trabeculae of the pedicle of the lower cervical spine presented a complex network of microstructures.The trabeculae near the cortical bone were lamellar and relatively compact,extending forward toward the vertebral body and backward toward the articular process lamina.Abatoid bone trabeculae extended into the medullary cavity and transformed into a network structure,and then into rod-shaped bone trabeculae.The rod-shaped bone trabeculae were sparsely distributed in the medullary cavity.(2)Statistical results of morphological parameters of bone trabeculae showed that bone volume fraction values in C4 and C5 were higher than that in C7(P＜0.05).The bone surface/bone volume value in C7 was higher than that in C3,C4 and C6(P＜0.05).The bone surface density of bone trabeculae in C7 was higher than that in C3,C4,C5 and C6(P＜0.05).Trabecular thickness in C7 was higher than that in C3,C4 and C5(P＜0.05).Bone surface/bone volume and bone surface density of the left pedicle bone trabecular were greater than those on the right side(P＜0.05).(3)The microstructural changes of C3-C7 were summarized,in which the load capacity and stress of the C7 pedicle were poor,and the risk of injury was high in this area.
ABSTRACT
BACKGROUND:The calcaneus is located in the lower posterior part of the foot and is heavily stressed.Calcaneus is complex and irregular in shape,surrounded by thin cortical bone and filled with a large number of trabeculae.The study of the microstructure,movement,and distribution of trabeculae is helpful to improve the understanding of calcaneus fracture. OBJECTIVE:The image data of calcaneus were obtained by scanning the calcaneus specimens with micro-computed tomography,and the structure of trabecular bone in calcaneus was analyzed to explore the morphology,distribution and structural characteristics of trabecular bone in calcaneus. METHODS:Dry adult calcaneus specimens were continuously scanned by micro-computed tomography,and the images were obtained after scanning and stored in DICOM format.Image data were imported into Hiscan Analyzer software to display clear and complete images of the sagittal plane,coronal plane,and the horizontal plane of the adult calcaneus.The trabecular movement of bone was observed layer by layer.According to the trabecular movement characteristics,the sagittal plane of the calcaneus was divided into six parts.A 49-mm2 region of interest was selected for each part at the same thickness as 7 mm.The three-dimensional microstructure of calcaneus and trabecular bone was obtained after three-dimensional reconstruction.After binarization,the volume fraction,surface density,trabecular thickness,trabecular space,and trabecular number parameters of the trabecular bone in the region of interest were calculated by software. RESULTS AND CONCLUSION:(1)The cortical layer of the calcaneus was very thin and filled with a large amount of cancellous bone,and the cortical layer of the horn of Gissane was obviously thickened.(2)The trabecular volume fraction in the upper part of the calcaneus was greater than that in the anterior part of the lower part of the calcaneus,the central triangle,the posterior part of the lower part of the calcaneus,and the base of the calcaneus,and the trabecular volume fraction in the tubercle of the calcaneus was greater than that in the anterior part of the lower part of the calcaneus,the central triangle,the posterior part of the lower part of the calcaneus,and the base of the calcaneus.The surface density of the trabecular bone in the tubercle of the calcaneus was higher than that in the front of the lower calcaneus,the middle triangle area,and the bottom of calcaneus,and the surface density of the trabecular bone in the upper part of calcaneal bone,and the lower part of the calcaneus was higher than that in the middle triangle area.The thickness of the trabecular bone in the upper part of the calcaneus was greater than that in the tubercle of the calcaneal bone.The bone trabecular space in the middle triangle was larger than that in the upper part of the calcaneus and calcaneal tubercles.The number of bone trabeculae in the calcaneal tubercles was greater than that in the middle triangle area.(3)These results indicate that the trabeculae of rod bone were mainly distributed in the middle triangle area.The surface density of trabeculae was the smallest,the volume fraction was smaller,and the space between trabeculae was the largest.This part of the bone is relatively loose.The compression resistance is poor when subjected to high impact.The trabecular bone fractures first occur,which is a prone site for fractures.
ABSTRACT
Aims: To evaluate the effi cacy of autologous platelet- rich fi brin in regeneration of bone and to assess clinical compatibility of the material in mandibular third molar extraction socket. Materials and Methods: This study was conducted in 20 patients visiting the out patient department of Oral & Maxillofacial Surgery, Subbaiah Institute of Dental Sciences. Patients requiring extraction of bilateral symmetrical mandibular third molars were taken for the study. Following extraction, platelet rich fi brin prepared from patients own blood was placed in one extraction socket. The patients were assessed for postoperatively pain, periodontal pocket depth and bone blending and trabecular formation. Radiological assessment of the extraction site was done for a period of 6 months to evaluate the change in bone density. Results: All the local signs and symptoms of infl ammation were mild to moderate and subsided in normal course of time. Pain was less in study site compared to control site. Soft tissue healing was better in study site. Evaluation for bone blending and trabecular bone formation showed earlier in study (prf)site compared to control(non prf) site in 10 patients. The evaluation of bone density by radiological assessment showed the grey level values calculated at 4months at the prf site were comparatively higher than the average baseline value of bone density at extraction site in control site. Conclusion: The study showed that autologous PRF is biocompatible and has signifi cant improved soft tissue healing,bone regeneration and increase in bone density in extraction sockets. However a more elaborate study with a larger number of clinical cases is very much essential to be more conclusive regarding its effi cacy.
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Objective To study the effects of electromagnetic field (EMF) exposure on osteoporosis in ovariectomized mice. Methods Sixty 8-week-old female Kunming mice were divided into four groups at random: a sham operation group (group A), an ovariectomized group (group B), an EMF and ovariectomized group (group C) and a nilestriol and ovariectomized group (group D). Bilateral ovariectomies were performed on all mice except those in group A. The mice of group C were exposured to a 15 Hz, 1.0 mT electromagnetic field. The mice of group D were given at nilestriol 1.5 mg/kg/week. The bone mineral density (BMD) of the lumbar vertebrae was measured before the mice were sacrificed at the 12th week. Blood specimens were collected every two weeks to measure the ac-tivity of alkaline phosphatase (ALP) and the concentration of bone gamma-carboxyglutamic-acid-containing proteins (BGP), calcium and estradiol in the serum. Histological sections were taken to examine and analyze the changes in bone trabeculae in the lumbar vertebrae after 6 and 12 weeks. Results EMF at 15 Hz and 1.0 mT intensity signifi-cantly increased the activity of ALP and the concentrations of BGP and calcium in the serum. In addition, the absorp-tion of bone trabeculae in the lumbar vertebrae was significantly restrained. Conclusions EMF at 15 Hz and 1.0 mT can restrain the development of osteoporosis in ovariectomized mice.
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Objective: To determine the failure mode of depressive osteochondral fracture under the maximum compressive load. Design: An experimental cadaveric study. A compressive load was applied through an indenter on a femoral condyle to create a depressive osteochondral fracture until the maximum load was reached. Background: Most depressive osteochondral fractures occur without a gross articular cartilage injury because a large amount of load is reabsorbed by the surrounding tissues, especially the subchondral bone under the cartilage. We asked what the mode of depressive osteochondral fracture is. It might function as a load adsorber from the articular cartilage. Methods: Three groups of depressive osteochondral fractures were studied. Croup 1 consisted of 12 pieces of middle third of normal median and lateral femoral condyles. Groups 2 and 3 consisted of 12 pieces of osteoporotic and osteosclerotic middle of both femoral condyles. Using a universal testing machine, a depressive osteochondral fracture was created by applying a uniaxial compressive load through an indenter until the load rose to the maximum level. At that point, the load applied was stopped in order to minimize the extent of subchondral trabeculae fracture. Maximum load was recorded. Pressure and stiffness were calculated. The pattern of depressive fracture was studied histologically. Results: The failure mode of depressive osteochondral fracture wan such that the bone under the articular cartilage had a subchondral plate fracture, an interlacing of bone trabeculae under the plate, and a few fractures of the bone trabeculae. The interlacing of subchondral bone trabeculae was most evident in the normal bone as compared with the osteoporotic and osteosclerotic bones. The osteosclerotic bone failed at the highest load, while the osteoporotic bone failed at the lowest. Conclusion: The subchondral plate fracture and the interlacing of subchondral bone trabeculae under the plate are the characteristics of the failure mode of depressive ostechondral fracture. This failure mode occurs before there is a discernible fracture of the subchondral bone trabeculae. The amount of load causing fracture depends on the quality of the bone. Relevance: The failure mode, especially the interlacing of subchondral bone trabeculae, night function as a load absorber from the articular cartilage. Therefore, the quality of subchondral bone is important for protection of the articular cartilage from compressive load injury.