bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uncinate processes and Luschka joints influence the biomechanics of the cervical spine: Quantification using a finite element model of the C5‐C6 segment
Authors: Clausen John D. , Goel Vijay K. , Traynelis Vincent C. , Scifert Jeffrey 
Published: February 2005

AbstractA fully three‐dimensional finite element model of a C5‐C6 motion segment of the human spine was developed and validated for the purpose of investigating the biomechanical significance of uncinate processes and Luschka joints. The original intact cervical model was modified to create two additional models. The first simulated the absence of Luschka joints by replacing the fissures with continuous annulus fibrosus and leaving the uncinate processes intact. The second model simulated a surgical resection of the uncinate processes, while leaving the Luschka joints intact. The results of these two models were compared with the intact model, which served as a baseline; thus, the relative contributions of these two structures to cervical motion were established With use of our model, it was possible for the first time, to provide quantitative data concerning the source of coupled motions in the lower cervical spine. In principle, the results from this model support the hypothesis of Penning and Wilmink. Our resultsindicate that the facet joints and Luschka joints are the major contributors to coupled motion in the lower cervical spine and that the uncinate processes effectively reduce motion coupling and primary cervical motion (motion in the same direction as load application), especially in response to axial rotation and lateral bending loads. Luschka joints appear to increase primary cervical motion, showing an effect on cervical motion opposite to that of the uncinate processes. Surgeons should be aware of the increase in motion accompanied by resection of the uncinate processes.
Reproducibility of the kinematics and kinetics of the lower extremity during normal stair‐climbing
Authors: Yu Bing , Kienbacher Thomas , Growney Eric S. , Johnson Marjorie E. , An Kai‐Nan 
Published: February 2005

AbstractThe purpose of this study was to examine the intrasubject reproducibility of the kinematic and kinetic measures of the lower extremity during normal stair‐climbing. Three‐dimensional video and force‐plate data were collected for three trials per subject during each of three conditions: ascending, descending, and level walking. Three‐dimensional angles and moments of the ankle, knee, and hip joints were calculated. The coefficient of multiple correlation was used to determine the intrasubject reproducibility of joint angles and resultant moments. Analysis of variance with repeated measures was conducted to compare the magnitudes of the coefficients between different steps, different joints, and different joint functions. The results showed that (a) generally, the kinematic and kinetic measures of normal subjects climbing stairs were reproducible; (b) the kinetic measures during the transition steps from level walking to ascending and from descending to level walking were significantly less reproducible than those during the other steps; (c) the data from the sagittal plane, were more reproducible than those from the other two planes; and (d) the kinetic measures were more reproducible than the kinematic measures, especially for abduction‐adduction and internal‐external rotation.
Structure and function of embryonic growth plate in the absence of functioning skeletal muscle
Authors: Germiller John A. , Goldstein Steven A. 
Published: February 2005

AbstractNormal growth and development of the skeleton require the presence of viable, actively contracting skeletal muscle throughout the fetal period. A chick embryo model of midgestation chemical paralysis and secondary muscle atrophy was used to test the hypothesis that functioning muscle stimulates the growth of long bones by influencing the proliferation, differentiation, and hypertrophy of chondrocytes in cartilage of the epiphysis and growth plate. Paralysis did not alter the overall developmental stage of the long bone or the organization of the growth plate. Compared with controls, however, uptake of bromodeoxyuridine in the paralyzed chick was reduced by 27‐55% in the chondroepiphysis and uppermost zone of the tibial growth plate, indicating reduced proliferation of chondrocytes. A specific reduction in the size of the proliferative zone and a reduced number of proliferating cells were also observed. By contrast, in the second, post‐proliferative zone of the growth plate, the height of the zone was unchanged and its area was only slightly reduced compared with controls. Finally, median hypertrophic cell profile area, a measure of cell size, was not significantly affected by paralysis, although frequency analysis revealed modest numerical reductions in the population of the largest hypertrophic chondrocytes in the paralyzed group. These data suggest that the role of functioning fetal muscle in maintaining proper skeletal growth may be mediated primarily through specific stimulation of the recruitment or proliferation of immature chondrocytes, or of both.
Characterization of a rabbit model of staphylococcal osteomyelitis
Authors: Smeltzer Mark S. , Thomas J. Roby , Hickraon Sandra G. , Skinner Robert A. , Nelson Carl L. , Griffith David , Parr Thomas R. , Evans Richard P. 
Published: February 2005

AbstractWe previously described a rabbit osteomyelitis model that involved the direct introductiof Staphylococcus aureus into devascularized bone. To further evaluate the model, we performed expeirijj aimed at correlating the microbiological, radiographic, and histologic parameters involved in the development of experimental osteomyelitis. Using the strain UAMS‐1, we achieved an infection rate of 75% with an inoculum as small as 2 × 103 colony‐forming unit's. However, development of significant radiographieja'TOifaife logic signs of disease required an inoculum of at least 2 × 104 colony‐forming units. Radiographic singns were minimal 1 week after infection and progressed steadily to a maximum 3 weeks after infection.‐, In contrasthistologic signs of disease were observed within 1 week and remained essentially unchanged throughout the4‐week evaluation period. Unlike the results obtained with UAMS‐1, rabbits infected with the heavily encapsulated Staphylococcus aureus, strain Smith diffuse exhibited little evidence of disease even whdrf'‐inreicl with 2 × 106 colony‐forming units. The reduced virulence of strain Smith diffuse was surprising given its greatly enhanced, Virulence (relative to UAMS‐1) in a murine peritonitis model of staphylococcal disease. These results suggest that UAMS‐1 expresses virulence factors that are important in the pathogeritesis of osteomyelitis and that some or all of these virulence factors are either absent or are not expressed jrisfraffl Smith diffuse. Most importantly, the results suggest that our model may be appropriate for the identificationf and characterization of these virulence factors.
Immunolocalization of cytokines and their receptors in adhesive capsulitis of the shoulder
Authors: Rodeo Scott A. , Hannafin Jo A. , Tom James , Warren Russell F. , Wickiewicz Thomas L. 
Published: February 2005

AbstractThe purpose of this study was to test the hypothesis that specific cytokines are involved in the initiation and evolution of the fibrotic process in adhesive capsulitis of the shoulder. After approval from the Institutional Review Board, biopsies of shoulder capsule and synovium were collected during shoulder arthroscopy from 19 patients with adhesive capsulitis, 14 patients with nonspecific synovitis and no fibrosis or clinical evidence of adhesive capsulitis, and seven patients undergoing surgery for another pathology who had a normal capsule and synovium. Immunohistochemical localization with monoclonal antibodies to transforming growth factor‐β and its receptor, platelet‐derived growth factor and its receptor, basic fibroblast growth factor, interleukin‐1β, tumor necrosis factor‐α, and hepatocyte growth factor was performed using standard immunoperoxidase techniques. The frequency of cytokine staining was correlated with the clinical diagnosis Synovial cells, fibroblasts, T‐cells, and B‐cells were identified with specific antibodies, and newly synthesized matrix was examined for type‐I and type‐III collagen by immunohistochemical staining. The predominant cell types present were synovial cells and fibroblasts. Staining for type‐III collagen in adhesive capsulitis tissues indicated new deposition of collagen in the capsule. There was staining for transforming growth factor‐β and its receptor, platelet‐derived growth factor and its receptor, interleukin‐1β, and tumor necrosis factor‐α in adhesive capsulitis and nonspecific synovitis tissues, compared with minimal staining in normal capsule. Staining was more frequent in snovial cells than in capsular cells. The frequency of cell and matrix staining for transforming growth factor‐β, platelet‐derived growth factor, and hepatocyte growth factor was greater in adhesive capsulitis tissues than in those from patients with nonspecific synovitis. No difference in the frequency of staining between primary (idiopathic) and secondary adhesive capsulitis was found. The results of this study indicate that adhesive/capsulitis involves both synovial hyperplasia and capsular fibrosis. Cytokines such as transforming growth factor‐β and platelet‐derived growth factor may be involved in the inflammatory and fibrotic processes in adhesive capsulitis. Matrix‐bound transforming growth factor‐β may act as a persistent stimulus, resulting in capsular fibrosis. Understanding the basic pathophysiology of adhesive capsulitis is an important step in the development of clinically useful antifibrotic agents that may serve as novel treatments for patients with this condition.
Nitric oxide and proteoglycan turnover in rabbit articular cartilage
Authors: Stefanovic‐Racic M. , Möllers M. O. , Miller L. A. , Evans C. H. 
Published: February 2005

AbstractArticular chondrocytes are known to synthesize large amounts of nitric oxide in response to exposure to interleukin‐1, but the role of this radical in proteoglycan turnover remains controversial. In this study, we used two different inhibitors of nitric oxide synthase, NG‐methyl‐L‐arginine and thiocitrulline, to study the effects of nitric oxide on the synthesis and breakdown of proteoglycan in rabbit articular cartilage. Synthes of nitric oxide by cartilage slices in response to treatment with interleukin‐1 and a partially purified mixture of synovial cytokines known as chondrocyte‐activating factors peaked during the first 2 days of culture and then fell to low levels, despite daily replenishment with fresh medium and cytokines to the cultures. The production of nitric oxide was completely inhibited by NG‐methyl‐L‐arginine and thiocitrulline. Interleukin‐1 and the chondrocyte‐activating factors inhibited proteoglycan synthesis and accelerated proteoglycan breat down in the slices of cartilage. Both nitric oxide synthase inhibitors substantially counteracted the suppression of prdteoglycan synthesis but exacerbated proteoglycan catabolism occurring in response to interleukin‐1 and the chondrocyte‐activating factors. The accelerated eatabolism was associated with increased levels of matrix metalloproteinases in the conditioned medium. This dual effect of nitric oxide complicates decision making with regard to the possible clinical applications of nitric oxide agonists or antagonists in diseases of cartilage.
Regulation of the expression of the type‐II collagen gene in periosteum‐derived cells by three members of the transforming growth factor–β superfamily
Authors: Ballock R. Tracy , Heydemann Ahlke , Izumi Toshihiro , Reddi A. Hari 
Published: February 2005

AbstractAlthough transforming growth factors‐β and bone morphogenetic proteins are both capable of inducing bone formation in vivo, the target cells of their osteoinductive actions may be different. To evaluate periosteal cells as potential targets of the actions of transforming growth factor–β and bone morphogenetic protein, we investigated the ability of three members of the transforming growth factor–β superfamily to modulate expression of the gene encoding the α1(II) chain of type‐ll collagen in periosteum‐derived cells in Vitro. The results demonstrate that transforming growth factor–β mRNA is expressed by periosteum‐derived cells and that exogenous transforming growth factor–β1 acts to upregulate expression of the gene encoding collagen α1(II). This effect was observed as early as 12 hours after administration of transforming growth factor–β1 but was not observed in response to bone morphogenetic proteins 3 or 4. No synergy was demonstrated between transforming growth factor–β1 and bone morphogenetic protein‐3 in the ability to upregulate expression of the collagen α1(II) gene. These results support the hypothesis that committed periosteal mesenchymal cells are cellular targets of the action of transforming growth factor–β.
Correspondence between theoretical models and dual energy X‐ray absorptiometry measurements of femoral cross‐sectional growth during adolescence
Authors: van der Meulen Marjolein C. H. , Marcus Robert , Bachrach Laura K. , Carter Dennis R. 
Published: February 2005

AbstractWe have developed an analytical model of long bone cross‐sectional ontogeny in which appositional growth of the diaphysis is primarily driven by mechanical stimuli associated with increasing body mass during growth and development. In this study, our goal was to compare theoretical predictions of femoral diaphyseal structure from this model with measurements of femoral bone mineral and geometry by dual energy x‐ray absorptiometry. Measurements of mid‐diaphyseal femoral geometry and structure were made previously in 101 Caucasian adolescents and young adults 9–26 years of age. The data on measured bone mineral content and calculated section modulus were compared with the results of our analytical model of cross‐sectional development of the human femur over the same age range. Both bone mineral content and section modulus showed good correspondence with experimental measurements when the relationships with age and body mass were examined. Strong linear relationships were evident for both parameters when examined as a function of body mass.
Robertsonian translocations in Paget's disease of bone
Authors: Mills Barbara G. , Oizumi Jun , Kudo Emily , Rude Robert 
Published: February 2005

AbstractThe karyotypes of 14 patients with Paget's disease of bone were studied. The patients were recruited from our bone metabolism clinic where they received specific therapy for their skeletal disease. Eight of the 14 patients had chromosomal translocations localized to the D and G groups. None of the patients were related to one another, nor had any had the same lifelong environment. Thus, 57% of a sample of active patients with Paget's disease had Robertsonian translocations. By comparison, an age and sex‐matched group of eight controls and 13 patients with osteoporosis who had been treated with bisphosphonates demonstrated no Robertsonian translocations. The prevalence of Robertsonian translocations in 14,000 newborns was reported to be 0.1%. These data suggest that a factor from the environment introduced during the lifetime of the patient could be present and could, in addition to genetic factors, affect gene replication during the development of Paget's disease.
Regional and temporal changes in the acoustic properties of fracture callus in secondary bone healing
Authors: Harten Robert D. , Lee Francis Y. , Zimmerman Mark C. , Hurowitz Eli , Arakal Rajesh , Behrens Fred F. 
Published: February 2005

AbstractControlled fractures were created in the right femora of 17 male Sprague‐Dawley rats. The fractured limbs were harvested at 2, 4, 6, and 8 weeks after fracture, fixed, and embedded in polymethylmethacrylate. Midsagittal sections from each animal were evaluated with a scanning acoustic microscope, a device that generates an acoustic impedance map of the scanned material. The impedance of the fracture callus was measured in six regions on each specimen. These regions were chosen in an effort to distinguish between the impedance of the callus formed through intramembranous or endochondral ossification, and we found that the time course of increasing impedance differed for the fracture callus formed through the two pathways. Additionally, we found a significant difference in the mean impedance of the callus at each time period (p ≤ 0.0013 for all comparisons), which resulted in an extremely linear relationship (r2 = 0.999) between mean callus impedance and healing time. This experimental model has become a popular choice for the investigation of fracture healing. As such, an accurate determination of the mechanical properties of the fracture callus is often sought. We propose that the implementation of scanning acoustic microscopy in the study of fracture healing may determine the changes in the material properties more accurately than conventional testing methods.
Influence of size and stability of the osteotomy gap on the success of fracture healing
Authors: Claes Lutz , Augat Peter , Suger Gebhard , Wilke Hans‐Joachim 
Published: February 2005

AbstractFlexible fixation of fractures with minimally invasive surgical techniques has become increasingly popular. Such techniques can lead to relatively large fracture gaps (larger than 5 mm) and considerable interfragmentary movements (0.2‐5 mm). We investigated the influence of the size of the fracture gap, interfragmentary movement, and interfragmentary strain on the quality of fracture healing. A simple diaphyseal long‐bone fracture was modeled by means of a transverse osteotomy of the right metatarsus in sheep. In 42 Sheep, the metatarsus was stabilized with a custom‐made external ring fixator that was adjustable for gap size and axial interfragmentary movement. The sheep were randomly divided into six groups with three different gap sizes (1, 2, or 6 mm) and small or large interfragmentary strain (approximately 7 or 31%). The movement of the fracture gap was monitored telemetrically by a displacement transducer attached to the fixator. After 9 weeks of healing, the explanted metatarsus was evaluated mechanically in a three‐point bending test to determine bending, stiffness and was radiographed to measure the amount of periosteal callus formation. Increased size of the gap (from 1 to 6 mm) resulted in a significant reduction in the bending stiffness of the healed bones. Larger interfragmentary movements and strains (31 compared with 7%) stimulated larger callus formation for small gaps (1‐2 mm) but not for larger gaps (approximately 6 mm). The treatment of simple diaphyseal fractures with flexible fixation can be improved by careful reduction of the fracture; this prevents large interfragmentary gaps. The experimental fracture model for the metatarsus showed that the healing process was inferior when the gap was larger than 2 mm.
Lengths of hamstrings and psoas muscles during crouch gait: Effects of femoral anteversion
Authors: Schutte Lisa M. , Hayden Scott W. , Gage James R. 
Published: February 2005

AbstractRecent studies of muscle lengths measured by means of gait analysis data and musculoskeletal models have suggested that in many cases of crouch gait in patients with cerebral palsy, the hamstrings are of normal length and the psoas muscles are short. In these studies, however, muscle lengths were calculated by applying kinematic data from a child's joint to a normal adult model. Children with cerebral palsy and other disorders generally do not have normal bone architecture but instead have muscle attachment points and muscle paths altered by osseous deformities. In this study, we explored the consequences of using normal adult musculoskeletal models to calculate hamstring and psoas lengths for children with cerebral palsy. Specifically, for a group of subjects with cerebral palsy who walk with a crouch gait, we investigated the changes in muscle lengths that arise when a patient‐specific representation of clinically measured femoral anteversion was added to a model of normal musculoskeletal geometry. The calculation of psoas muscle length was found to be very sensitive to femoral anteversion, whereas the calculation of hamstrings length was found to be relatively insensitive to this osseous deformity.
In vivo forces during remodeling of a two‐segment anterior cruciate ligament graft in a goat model
Authors: Lundberg William R. , Lewis Jack L. , Smith Joel J. , Lindquist Conrad , Meglitsch Toni , Lew William D. , Poff Bradley C. 
Published: February 2005

AbstractAn existing goat model was used to measure in vivo graft forces during walking, to determine if the forces set at surgery change over time under the same external load and if the forces in the graft during in vivo function can be dictated by the forces set at surgery. The anterior cruciate ligament was reconstructed in 12 goats with use of a composite graft consisting of a bone‐patellar tendon‐bone autograft and a synthetic augmentation segment. The forces in the graft segments were established intraoperatively by a force‐setting technique. In five animals, the tendon segment was set to carry 90% of the total graft force, and in the seven other animals, the augmentation segment was set to carry 90% of the total force. The total graft force was the same in all animals. Graft forces due to anterior tibial loads of 67 N were measured before and after fixation and 6 weeks after surgery with the use of buckle transducers mounted extra‐articularly over the anterior tibia. They were also measured during straight, level walking at 6 weeks. The forces changed significantly from just after surgery to 6 weeks later, such that the initially set load‐sharing was eliminated by 6 weeks. At 6 weeks, a relatively smooth gait had been achieved, and the maximum total graft force in each animal during walking averaged 35 N and was of similar magnitude to forces generated by the anterior tibial loads of 67 N with the animal anesthetized. After fixation, forces in the tendon graft segments were significantly different between the group with high set forces and that with low set forces. At 6 weeks, when functional joint loads were approaching normal levels, the graft segment forces for the two groups were not significantly different. Load‐sharing between tendon and augmentation segment and load in the tendon segment at 6 weeks could not be dictated at surgery.