bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three‐dimensional anatomy of the cancellous structures within the proximal femur from computed tomography data
Authors: Elke Reinhard P. E. , Cheal Edward J. , Simmons Craig , Poss Robert 
Published: February 2005

AbstractQuantitative computed tomography was used to investigate the three‐dimensional architecture and the density distribution of the cancellous structures of the proximal femur. We examined 10 femora from the cadavera of 10 individuals, 47‐83 years old at the time of death. Three anatomic elements could be distinguished: the epiphysis, the epiphyseal scar, and the metaphysis. Although these elements constitute a functional unit, their individual cancellous patterns revealed significant structural differences. The epiphyseal segment had a more reticulate cancellous appearance, whereas the metaphysis demonstrated a more longitudinally oriented trabecular distribution. The three‐dimensional reconstruction of the densest epiphyseal trabecular groups showed two different patterns: a dumbbell type (found in eight bones) and a hemispheric type (found in two bones). The epiphyseal scar was a clearly recognizable high‐density structure found in all 10 bones. The epipyseal scar‐diaphysis angle was 13–26° higher than the center column‐diaphysis angle. The scar appeared as a tray supporting the epiphyseal cancellous structures, supported itself by the metaphyseal intersection of the main compressive and the arcuate trabecular systems. This intersection always occurred in a relatively small band‐shaped zone under the central third of the epiphyseal scar. These three discrete anatomical segments within the proximal femur may reflect developmental and functional adaptations determined by joint incongruity or eccentric muscular activity. The present data will serve as a reference for future studies in which the cancellous patterns are used to help with the early diagnosis of states of disease.
Comparison of the electrical and dielectric behavior of wet human cortical and cancellous bone tissue from the distal tibia
Authors: Saha Subrata , Williams Paul Allen 
Published: February 2005

AbstractWe compared the electrical and dielectric properties of wet human cortical and cancellous bone tissue from the distal tibia. The relationships between the electrical and dielectric behavior of cortical and cancellous bone and variables of measurement such as frequency and direction (orientation) were evaluated. In general, the resistivity of human cortical bone was found to be approximately 3.1 times more than that of cancellous bone in the longitudinal direction and least 25 times more in the transverse directions. The dielectric permittivity of human cortical bone was approximately 3.9 times that of cancellous bone in the longitudinal direction, whereas in the transverse directions it was about 0.65 times greater. Measurement variables such as frequency and orientation appeared to affect cancellous and cortical bone differently. Strong correlations were found between the electrical properties in one direction and the electrical properties in the other two directions; however, these relationships differed for the samples of cortical and cancellous bone.
Comparison of residual stability in thoracolumbar spine fractures using neutral zone measurements
Authors: Ching Randal P. , Tencer Allan F. , Anderson Paul A. , Daly Colin H. 
Published: February 2005

AbstractBecause treatment algorithms for spinal injuries depend largely on the clinical assessment of stability after injury, this study both quantified and compared the mechanical stability after three different patterns of injury in the thoracolumbar spine. We created compression fractures, burst fractures, and flexion‐distraction injuries in 26 thoracolumbar specimens from human cadavers in order to compare residual stability as a function of type of injury. Spinal stability was evaluated using measurements of the boundaries of the neutral zone, which provide a measure of spinal laxity in various directions of motion. An increase after injury was indicative of greater spinal laxity and hence reduced residual stability. Geometric characteristics (or parameters) of the neutral zone boundaries were used for statistical comparison between the types of injury. Of the three groups, burst fractures retained the least residual stability and compression fractures, the greatest. The angular ranges of motion in the neutral zone for burst fractures demonstrated increases (compared with average values for intact specimens) of 154% in flexion‐extension. 134% in lateral bending, and 108% in torsion after injury. The results for flexion‐distraction injuries were similar to those for burst fractures in flexion‐extension (126%) and torsion (62%); however, more residual stability was retained in lateral bending than was seen for burst fractures (48%). Compression fractures retained the most residual stability, with increases in motion of 40% in flexion‐extension, 56% in lateral bending, and 3% in torsion. These findings may be useful in determining the necessity for surgical stabilization of the spine and selection of the appropriate system of fixation.
Microvessel endothelial cells and pericytes increase proliferation and repress osteoblast phenotypic markers in rat calvarial bone cell cultures
Authors: Jones A. R. , Clark C. C. , Brighton C. T. 
Published: February 2005

AbstractTo investigate the influence of microvessel cells on osteoblasts, we exposed osteoblast‐enriched cultures of rat calvarial cells to cultured endothelial cells and pericytes using feeder‐layer co‐cultures, co‐culture dish inserts, and conditioned media experiments. When co‐cultured with growth‐arrested feeder‐layers of endothelial cells or pericytes for 10 days, bone cell cultures showed an increase in cell number and reduction in alkaline phosphatase activity. The response of bone cells to endothelial cells was nearly twice their response to pericytes. A similar response was demonstrated by exposure to microvessel cells in co‐culture dish inserts and by exposure to media conditioned by microvessel cells. In long‐term cultures of bone cells, the levels of osteocalcin and the number of mineralized nodules both were reduced by exposure to media conditioned by the microvessel cells. Transient exposure to conditioned media from the microvessel cell cultures for 3 days, during the period from initial plating to cell confluence, produced nearly the same effect on the cultures of bone cells as did continuous exposure to these conditioned media. The influence of isolated microvessel cells on osteoblast‐enriched calvarial cells was found to be primarily mitogenic, mediated by soluble factors, independent of cell contact, and a cause of prolonged reduction in the expression of early and late markers of the osteoblast phenotype.
Changes in innervation of long bones after insertion of an implant: Immunocytochemical study in goats with antibodies to calcitonin gene‐related peptide and B‐50/GAP‐43
Authors: Buma P. , Elmans L. , Oestreicher A. B. 
Published: February 2005

AbstractIn this study, we describe the distribution of fibres that contain calcitonin gene‐related peptide in normal bones and in bones that are remodeling after insertion of an implant. With routine histology and antibodies to calcitonin gene‐related peptide, small neural and free‐running fibres staining positively for calcitonin gene‐related peptide were found in the periosteum, endosteum, and cortical bone of the tibia in the goat. In many cases, the free‐running fibres were associated with blood vessels that entered the bone through Volkmann's canals. The endosteal blood supply was destroyed as a result of insertion of the implant. The necrotic bone was no longer innervated, as shown by the lack of staining for the antibodies. At 6 weeks, a repair phase started with revascularization and remodeling of the necrotic endosteal bone. During this repair phase, there was increased innervation with fibres containing calcitonin gene‐related peptide in the remodeling cavities at the interface between living and necrotic bone. These fibres ended blindly, with many large varicosities, and could be demonstrated by immunostaining with monoclonal antibodies to B‐50/growth associated protein‐43, an antibody to outgrowing neuronal fibres. The correlative occurrence between extensive sprouting of fibres containing calcitonin gene‐related peptide and the remodeling of necrotic endosteal bone suggests that sensory fibres with calcitonin gene‐related peptide have a regulatory role in the control of angiogenesis or of bone remodeling associated with the insertion of an implant, or with both processes.
Thermal response and torque resistance of five cortical half‐pins under simulated insertion technique
Authors: Wikenheiser Mark A. , Markel Mark D. , Lewallen David G. , Chao Edmund Y. S. 
Published: February 2005

AbstractA model was developed that can quantitate heat generation during placement of half‐pins in cortical bone. Five half‐pins were tested to assess differences in insertion torque, heat generation, and microdamage at the pin‐bone interface. Thin thermocouple probes were placed 0.5 mm from the track of the pin and within the pin to measure its temperature during insertion. Scanning electron microscopy was used to view the pin‐bone interface to assess the microdamage during placement. The design of the tip of the pin influenced insertion torque and heat generation. Higher heat generation was measured when a thermocouple was placed within the pin itself and less was measured when thermocouple probes were placed within bone samples 0.5 mm from the impending pin track. Furthermore, insertion torque and thermal responses were related, but there were no significant differences in microdamage to bone when different pins and drilling/tapping techniques were used. Due to the significant heat generation at the pin‐bone interface, proper cooling with saline irrigation should be applied during pin insertion regardless of the design of the pin. The microdamage observed at the surface of the pin track may have significant implications with regard to loosening of pins, but such effects must be studied with in vivo models.
Effect of bone cylinder length on distraction osteogenesis in the rabbit tibia
Authors: Windhager R. , Tsuboyama T. , Siegl Helga , Groszschmidt K. , Seidl G. , Schneider B. , Plenk H. 
Published: February 2005

AbstractThe viability and osteogenic potential of bone cylinders for bone transport was investigated in one tibia of 18 mature male New Zealand rabbits. The length of the bone cylinder was equal to or twice that of the diameter of the tibia. The cylinder was cut subperiosteally with an externally cooled oscillating saw from a lateral approach, after a specific unilateral external fixator had been applied. To simulate bone transport, one end of the cylinder was fixed to the distal bone stump by a cerclage wire and healing and revascularization was prevented by an interposed expanded polytetrafluoroethylene membrane. The periosteum was readapted and sutured, and distraction began 10 days postoperatively at 0.25 mm/12 hours for 22 days. New bone formation in the distraction gap was quantified by dual energy x‐ray absorptiometry and by computer‐assisted histomorphometry of polyfluorochrome‐labeled undecalcified bone sections and corresponding microradiographs. In half of the animals with each size cylinder, osseous bridging occurred, so the findings on distraction osteogenesis are reported only for the remaining nine animals. Generally, centripetal mineralization of the gap with two distinct zones of ripening bone structures and a central radiolucent fibrocartilaginous zone could be distinguished. Neither absorptiometry nor histomorphometry showed significant differences in the overall amount of this new bone formation for the bone cylinders of two different lengths. However, osteogenesis was significantly greater at the proximal end than at the cylinder. New bone was formed predominantly from endosteal sites in the smaller cylinders and from periosteal sites in the larger cylinders. Histologically, there was complete necrosis of both sizes of cylinders, followed by revitalization through newly formed vascular channels. This process started earlier and was more pronounced with the smaller bone cylinders. It is concluded from these experiments that even careful subperiosteal osteotomy with an oscillating saw leads to necrosis of both small and large bone cylinders. However, distraction osteogenesis still can be achieved and is mediated mainly by the revitalized endosteum in the smaller cylinders and by the periosteum, which apparently can be better preserved, in the larger cylinders. These results demonstrate the feasibility of even extremely small bone cylinders for distraction osteogenesis; the minimum length is determined only by the possibility of stable fixation.
Ilizarov callus distraction produces systemic bone cell mitogens
Authors: Holbein Oliver , Neidlinger‐Wilke Cornelia , Suger Gebhard , Kinzl Lothar , Claes Lutz 
Published: February 2005

AbstractWe tested the hypothesis that the application of strain during callus distraction induces systemic osteoblast stimulating factors that enhance osteoblast activity both locally and systemically. To study the systemic occurrence of strain‐induced osteoblast stimulating factor during callus distraction, we investigated the mitogenic capacity of sera from 12 patients who had undergone callus distraction on the osteoblastic cell line SaOS‐2 (part I). Serum samples from six patients who had undergone rigidly fixed high tibial osteotomy (i.e., without distraction) served as controls. The sera were assayed for platelet‐derived growth factor and transforming growth factor‐beta. In part II of the study, the in vitro effects of mechanical strain were investigated in a simplified model by cyclic stimulation of osteoblast cultures isolated from cortical bone explants from the same patients; a specially developed apparatus was used for cell‐stretching. Sera taken during the third to fourth week of callus distraction demonstrated a significant increase in proliferation of SaOS‐2 cells (p < 0.005). In contrast, sera from patients who had had an osteotomy failed to induce or decreased the mitogenic capacity of SaOS‐2 cells. The concentration of platelet‐derived growth factor increased significantly (p < 0.01) in sera from both the patients who had undergone callus distraction and the controls who had had osteotomy. However, the level of transforming growth factor‐beta was increased (p < 0.05) in the sera from the patients who had distraction (sera that stimulated proliferation of SaOS‐2 cells), but the level was not increased in the sera from patients who had osteotomy. Cyclic stretching of osteoblasts in vitro stimulated proliferation (p < 0.05) and increased the cellular production of transforming growth factor‐beta significantly (p < 0.05). These findings suggest that mechanically stimulated osteoblasts have the potential to increase proliferation and to produce additional mitogens in response to cyclic strain. This study supports the notion that mechanically stimulated tissue induces systemic factors that enhance osteoblast activity and thus influence the formation of callus. Isolation and characterization of these factors potentially could lead to serum assays to predict osteogenesis during callus distraction.
Comparison of allograft/endoprosthetic composites with a step‐cut or transverse osteotomy configuration
Authors: Markel Mark D. , Wood Suzanne A. , Bogdanske John J. , Rapoff Andrew J. , Kalscheur Vicki L. , Bouvy Bernard M. , Rock Michael G. , Chao Edmund Y. S. , Vanderby Ray 
Published: February 2005

AbstractThis study was designed to compare the biomechanical and functional characteristics of allograft/endoprosthetic composites of the proximal 25% of the femur repaired with either a transverse or a step‐cut osteotomy, using a canine model (10 dogs, five with each type of osteotomy). Serial radiography and weight‐bearing studies were performed monthly, and mechanical testing was done 6 months after surgery. The femora were tested in torsion and compared with the contralateral control (insertion of a femoral component but no osteotomy). At 6 months, the composites with a step‐cut osteotomy had 36% greater structural stiffness than the composites with a transverse osteotomy (p < 0.005) and 121% greater maximum torque at failure than the controls (p < 0.005), without greater structural stiffness. Evaluation of peak vertical ground reaction forces revealed significantly greater weight‐bearing on the experimental limb in dogs with a transverse osteotomy. The results of this relatively short‐term study were mixed. Despite the increased structural stiffness of the allograft/endoprosthetic composite with a step‐cut osteotomy, the dogs with this type of reconstruction had decreased weight‐bearing throughout the course of the study. The step‐cut osteotomy may augment the stability of the allograft/endoprosthetic composite, allowing faster healing (as demonstrated by the results of mechanical testing), but in some way, not understood, may cause pain in the reconstructed limb. Longer term studies are needed to answer these questions and to determine whether alteration of the traditional transverse osteotomy has any advantage.
Osteosarcoma oncogene expression detected by in situ hybridization
Authors: Wang Humin , Rodgers William H. , Chmell Michael J. , Svitek Chris , Schwartz Herbert S. 
Published: February 2005

AbstractFifteen archival human osteosarcoma specimens were examined by in situ hybridization for the expression of human and mouse transforming growth factor‐β (isoforms 1, 2, and 3), c‐fos, and metalloproteinase (stromelysin‐3 and matrilysin). Osteosarcoma subtypes were confirmed by review of patients' radiographs, histopathology, and age at diagnosis. The outcome and method of treatment were documented. The subtypes of osteosarcoma consisted of nine conventional osteosarcomas and two each of fibroblastic, telangiectatic, and post‐radiation osteosarcomas. Each specimen was histologically examined under light microscopy, and then adjacent paraffin sections were assayed with sense and anti‐sense RNA probes by in situ hybridization. The probes localized to the neoplastic cells, confirming the methodology of the technique. Human transforming growth factor‐β1 had the most uniform binding affinity to the osteosarcomas examined and was more specific in binding than mouse transforming growth factor‐β1. Specific mRNA encoding for the transforming growth factor‐βs, c‐fos, and metalloproteinases are detectable in patterns within osteosarcoma cells, and collectively, their expression parallels the different histopathologic subtypes. The less differentiated subtypes (telangiectatic and post‐radiation osteosarcomas) expressed the fewest molecular markers. Osteosarcoma is a heterogeneous tumor. Differential expression of matrilysin in osteosarcoma is the first reported detection of metalloproteinase activity in human skeletal sarcoma.
Incorporation of polylactide‐polyglycolide in a cortical defect: Neoangiogenesis and blood supply in a bone chamber
Authors: Winet H. , Hollinger J. O. , Stevanovic M. 
Published: February 2005

AbstractErodible polymers are an alternative to metals for fracture fixation (for example, in the malleolus) and for maxillofacial reconstruction. In this study, the vascular response to eroding polylactide‐polyglycolide copolymer threads was observed chronically in a bone chamber implant, with use of intravital microscopy. A bone chamber implant loaded with 100 μm thick polylactide‐polyglycolide threads was implanted into the right tibia in 15 mature female New Zealand White rabbits. Periodic intravital microscopic observations were performed from the third to the tenth or twelfth week after implantation. Vascularization, blood flow, and trabecular growth into the chambers from the medial cortex were recorded on videotape and analyzed using digital image processing. A statistically significant delay of neo‐osteogenesis in the presence of this copolymer was described in an earlier report. The present report describes the measures of neoangiogenesis and blood supply; there was a significant delay in neoangiogenesis. It is suggested that both delayed angiogenesis and osteogenesis were secondary consequences of the macrophage response to slowly eroding poly‐L‐lactide crystal nanoparticles and the influence of reduced nutrient exchange. The lesser effect on blood supply and vascular volume fraction was seen to be linked to the slowing down of angiogenesis, as the latter allowed vessels to mature, with a widening of their calibers. This homeostatic adjustment was interpreted as being only partially successful in restoring control levels of oxygen delivery, because resulting increases in vessel surface area did not reach control levels. Thus, in the presence of eroding polylactide‐polyglycolide, the oxygen supply and extravasation of other nutrients may be below normal during healing phases when the need is critical.
Hindlimb suspension diminishes femoral cross‐sectional growth in the rat
Authors: van der Meulen Marjolein C. H. , Morey‐Holton Emily R. , Carter Dennis R. 
Published: February 2005

AbstractGrowth, functional adaptation, and torsional strength were examined in the femora of 39‐day‐old male Sprague‐Dawley rats subjected to hindlimb suspension for 0, 1, 2, 3, or 4 weeks and were compared with measurements for age‐matched control animals. Our goal was to understand the effect of reduced loading on the normal age‐related changes in femoral properties during growth. The control animals exhibited growth‐related increases in all geometric and torsional properties of the femur. The mean body mass and femoral length of the hindlimb‐suspended rats were similar to those of the controls throughout the experiment. Over 4 weeks, the femoral cross‐sectional and torsional measurements from the hindlimb‐suspended rats demonstrated increases in comparison with the basal values (+33% cross‐sectional area, +64% polar moment of inertia, +67% ultimate torque, and +181% torsional rigidity), but the age‐matched controls showed significantly greater growth‐related increases (+71% cross‐sectional area, +136% polar moment of inertia, +127% ultimate torque, and +367% torsional rigidity). The differences in femoral structural strength between the hindlimb‐suspended animals and the age‐matched controls were attributable to differences in altered cross‐sectional geometry.