bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acute staphylococcal septic arthritis: The effect of cloxacillin therpy in an avian model
Authors: Patel Harjit , Nade Sydney 
Published: February 2005

AbstractAn experimental model of acute staphylococcal septic arthritis in chickens was used to study the effect of different therapeutic regimens of the antibiotic cloxacillin on the natural history of the disease. Three different theapeutic regimens were used in order to assess the effect of increasing the frequency and of delaying the commencement of administration. The results were assessed by measurement of animal growth rate, clinical condition, bacterial and leukocyte counts in synovial fluid, and histological appearance. An inadequate dosage regimen (a single daily dose) prevented spread of bacteria but did not control abscesses. Delay in commencing treatment permitted persistence and spread of abscesses with destruction of the secondary (epiphyseal) ossification center and even transphyseal spread into metaphyseal bone. Repair by fibroblasts was mainly seen in articular and epiphyseal cartilage but was not seen in the epiphyseal ossification center during the duration of the experiments (up to 18 days). Synovial fluid sampling with measurement of leukocyte and bacterial concentrations appears to be a useful guide to the effectiveness of treatment, because the numbers of cells correlate with the pathological process.
Cell populations of tendon: A simplified method for isolation of synovial cells and internal fibroblasts: Confirmation of origin and biologic properties
Authors: Banes Albert J. , Donlon Kathy , Link G. William , Gillespie Yancy , Bevin A. Griswald , Peterson Hugh D. , Bynum Donald , Watts Susan , Dahners Laurence 
Published: February 2005

AbstractTendons transmit the force of muscle contraction to bone to effect limb movement. Special structural and biological properties of tendon have developed to facilitate force transmission. The tendon has a complex organization of cells surrounding the collagen bundles inside tendon as well as at the tendon surface. Internal cells may act to maintain the bulk of the collagen in tendon. External cells in the epitenon may provide lubrication for tendon gliding. To develop better understanding of these processes and the roles the cell populations play, we isolated cells from the surface and interior of tendon and studied them in vitro. Flexor tendons from 8‐week‐old white Leghorn chickens were separated into two distinct cell populations: the outer synovial cells and the fibroblasts more internal in tendon. These cell populations were discernible by their locations in the intact tendon, determined by sequential enzymatic and physical release from their substrata. Initially, some cells eluted in Hanks' salt solution (HSS) (population 1); then synovial cells were released after a 2‐min treatment with 0.5% collagenase (population 2). Next, a population of synovial cells was released in high yield by treatment with 0.25% trypsin (step III, population 3). Step III, population 3 cells were used as synovial cells (SCs). Next, a population of SCs and fibroblasts were released by scraping with a rubber policeman (population 4). Subsequently, fibroblasts were released after incubation with 0.5% collagenase (population 5). A more direct procedure (procedure 2) to isolate the synovial and internal tendon cells involved treatment in 0.5% collagenase followed by sedimentation at 900 g. Cells that sedimented were largely fibroblasts, whereas the cells that remained at the top of the tube were largely SCs. Cells designated as SCs, isolated by procedure 2, most likely contained surface cells from epitenon and internal interfascicular cells from endotenon and paratenon. Surface tendon cells separated by sequential enzymatic and physical release from their substrata (by procedure 1) had all the following characteristics: distinct subpopulations of cells based on morphology; presence of cytoplasmic, lipid‐containing vesicles; decreased sensitivity to trypsin; and reduced generation time as compared with that of internal fibroblasts. Conversely, the internal fibroblasts (IFs) appeared to represent a more uniform population based on morphological characteristics.
Spinal deformity and back surface asymmetry in idiopathic scoliosis
Authors: Stokes Ian A. F. , Armstrong John G. , Moreland Morey S. 
Published: February 2005

AbstractStereo radiography and stereotopography were used to record simultaneously the three‐dimensional spinal and back surface shape of 141 patients with a clinical diagnosis of adolescent onset idiopathic scoliosis. Radiography confirmed 80 patients with single lateral curves (Cobb angle 5–87°); 59 with double curves (Cobb angle 5–61°). and two patients with triple curves. Orientation of each vertebra was measured by the lateral deviation from the spinal axis and the axial rotation. For each curve detected, the Cobb angle, the maximum deviation, the maximum axial rotation, and the sagittal plane curvature was measured. Topographic data were used to generate a profile of a cross‐section through the back of each vertebral level. This section was characterized by its axial rotation, deviation of its midpoint from the spinal axis, and area symmetry about the midpoint. Maximum values of these measurements in the region of each radiographic scoliosis curve were noted. Regression and correlation analysis showed (for each curve) a high correlation of apical vertebral lateral deviation with back surface axial rotation (r = 0.79) and with vertebral axial rotation (r = 0.79). The back surface rotation was less than vertebral rotation in magnitude, however, by a mean factor of 0.55. The measurement of the back surface asymmetry that gave the highest correlation with the skeletal deformity was the axial rotation. Relationships between skeletal and surface measures were similar for curves in thoracic and lumber regions and for patients with single and double curves. There is potential for clinical application of surface measurement techniques to prescription of orthoses and monitoring of changes due to progression or treatment.
Mechanical stresses and endochondral ossification in the chondroepiphysis
Authors: Carter Dennis R. , Wong Marcy 
Published: February 2005

AbstractIn 1911, Gebhardt used a photoelastic model to relate mechanical stresses to the ossification pattern of the chondroepiphysis. Pauwels later conducted a photoelastic study using the same model geometry to develop a theory that the secondary ossific nucleus originates at a position of high‐magnitude hydrostatic pressure where the shear stresses are zero. We conducted two‐dimensional finite element analyses of the model used by Gebhardt and Pauwels. We demonstrate that Pauwels's photoelastic results are correct but are based on the imposition of incorrect boundary conditions. When more realistic boundary conditions were used, the finite element results changed dramatically. These results suggest that (a) the ossific nucleus appears in an area of high shear (deviatoric) stresses; (b) the edge of the advancing ossification front (zone of Ranvier or ossification grove) also experiences high shear stresses; and (c) the joint surface, where articular cartilage forms, is exposed to high‐magnitude hydrostatic compression. These findings support the theory proposed by Carter and associates that intermittently applied shear stresses (or strain energy) promote endochondral ossification and that intermittently applied hydrostatic compression inhibits or prevents cartilage degeneration and ossification.
Effects of ankle taping on the motion and loading pattern of the foot for walking subjects
Authors: Carmines David V. , Nunley James A. , McElhaney James H. 
Published: February 2005

AbstractGait analysis was used to compare the ground reaction forces, ankle and foot rotations in the sagittal plane, and the center of pressure pattern beneath the right feet of seven normal subjects walking barefoot, with and without their right ankles taped in the neutral position. Instrumentation included a force plate, ankle goniometer, and two accelerometers mounted on top of the foot. The ground reaction forces showéd no change between the same ankle, taped and untaped. Taping served to reduce the range of ankle rotations in the sagittal plane by ∼20%, with a subsequent increase in the rotation about the metatarsal heads during heel‐up. Hell‐up occurred earlier in stance when the ankle was taped than with no taping. The vertical force graph was integrated over time when the center of pressure was located beneath the heel and the ball, resulting in two impulse measurements. The heel impulse decreased for each of the 7 subjects and 6 of the 7 subjects displayed an increase in the ball impulse due to taping, indicating that taping served to shift the load‐time history away from the heel and toward the ball. The results of this study may apply to fused ankle patients, who may suffer forefoot abnormalities subsequent to ankle fusion surgery.
Capacitively coupled electrical stimulation of bovine growth plate chondrocytes grown in pellet form
Authors: Armstrong Peter F. , Brighton Carl T. , Star Andrew M. 
Published: February 2005

AbstractPellets formed from isolated bovine growth plate chondrocytes were grown in various capacitively coupled electrical fields. The signals chosen were 0, 10, 100, 250, 500, 750, 1,000, and 1,500 V peak‐to‐peak, 60 kHZ. The effect on cell proliferation and matrix production of these different voltages was determined by [3H]thymidine and [35S]sulfate uptake, respectively. Cyclic AMP assays were done to determine if increases in either thymidine or sulfate uptake were associated with changes in cAMP levels. Significantly increased cell proliferation occurred at 500, 750, and 1,000 V peak to peak. The calculated electric fields were 1.5 to 3.0 × 10−2 V/cm. Proliferation was significantly inhibited at 1,500 V peak‐to‐peak with a calculated field of 4.5 × 10−2 V/cm. Little if any change was seen in cAMP levels at 30 or 60 min following application of the appropriate electric signals.
Comparative evaluation of the diffusion of tobramycin and cefotaxime out of antibiotic‐impregnated polymethylmethacrylate beads
Authors: Wilson Katharine J. , Cierny George , Adams Kenneth R. , Mader Jon T. 
Published: February 2005

AbstractBoth tobramycin and cefotaxime diffuse from antibiotic‐impregnated polymethylmethacrylate (PMMA) beads in quantities sufficient to inhibit the growth of bacteria on agar lawns or in broth cultures over a 28‐day period. Extraction of antibiotic from tobramycin or cefotaxime‐impregnated PMMA beads revealed that substantial amounts of both antibiotics remained within the beads despite 28 days of diffusion. Diffusion of antibiotic from the PMMA beads during the initial 3–5 days is much greater than occurs for the remainder of the 4‐week period. The results of the study suggest that perhaps tobramycin or cefotaxime‐impregnated PMMA beads would produce local levels of antibiotic high enough to sterilize a given dead space for a period of 28 days.
Streaming potentials in chemically modified bone
Authors: Otter Mark , Goheen Susanna , Williams Wendell S. 
Published: February 2005

AbstractDirect streaming experiments with no significant mechanical deformation have been performed to determine the constituent or constituents of bovine tibia mainly responsible for the production of streaming potentials. Following the approach of Frank and Grodzinsky (5), selective removal of either main constituent—collagen or hydroxyapatite—of the tissue was performed by chemical means, and the streaming potential was remeasured. Demineralized samples were prepared by soaking in formic acid/sodium citrate, and anorganic samples were prepared by boiling and also by sodium hypochlorite treatment. Demineralized samples demonstrated ζ potentials close to those of whole bone samples, whereas anorganic samples had much smaller ζ potentials. Collagen rather than hydroxyapatite mineral is therefore implicated as the constituent of whole bone dominating the streaming potential, in agreement with the observation that collagenous tissues containing no mineral phase, i.e., tendon and cartilage, also exhibit streaming potentials. No sign change was observed in whole bone at high NaCI concentration in solutions containing calcium or at low pH. Although the sign of the signal for anorganic bone could be reversed by the addition of Ca2+ or PO43+ to the test solutions, the sign of the signal in neither whole bone nor demineralized bone could be so affected. Sign changes in whole bone were observed only with solutions containing basic organic molecules, e.g., protamine sulphates.
Transient synovitis of the hip in the child: Increased levels of proteoglycan fragments in joint fluid
Authors: Lohmander L. S. , Wingstrand H. , Heinegård D. 
Published: February 2005

AbstractThe levels of proteoglycan antigen were measured in joint aspirates from the hip of children with transient synovitis, septic arthritis, Legg‐Calvé‐Perthes' disease and congenital and traumatic dislocation. Significantly increased levles were found in children with transient synovitis and septic arthritis as compared with other conditions. We propose that the proteoglycan antigens in the joint fluid were released from the articular cartilage in a partially degraded form as a result of an increased rate of proteolytic degradation. In transient synovitis, the source of proteolytic activity may be chondrocytes activated by factors released by synovial cells. The release of joint proteoglycan may cause a temporary increase in deformability of the hip cartilage of the child that could be an important pathogenetic mechanism in some of the sequelac of these diseases.
Effects of ingrowth, geometry, and material on stress transfer under porous‐coated hip surface replacements
Authors: Fyhrie D. P. , Carter D. R. , Schurman D. J. 
Published: February 2005

AbstractThree different interface geometries for porous ingrowth surface replacements of the hip were examined using two‐dimensional linear and non‐linear contact finite element analyses. The results indicate that incorporation of a nearly flat prosthesis interface between the surface replacement and the underlying cancellous bone may reduce stress shielding and improve stress transfer from the component. For all designs analyzed, the bone stress shielding was insensitive to component material stiffness when the elastic modulus was >30 MPa. The use of titanium instead of cobalt‐chrome (Co–Cr) as the prosthesis material therefore had a negligible effect on stress shielding.
Biomechanics of the craniocervical region: The alar and transverse ligaments
Authors: Dvorak Jiri , Schneider Erich , Saldinger Pierre , Rahn Berton 
Published: February 2005

AbstractIn the treatment of spine fractures and fracture‐dislocations, stability of the spine is one of the major objectives. In the craniocervical joint, the alar and transverse ligaments provide much of the stability of the healthy spine. Because the anatomy appears well described, the contribution of each of these structures so far has received little attention. The alar ligament restrains rotation of the upper cervical spine, whereas the transverse ligament restricts flexion as well as anterior displacement of the atlas. A lesion in one or both structures can produce damage to the neural structures and/or cause pain. To investigate the possible role of each of these ligaments, a mechanical and histologic study of the upper cervical spine was made. The bone‐ligament‐bone complex of the alar and transverse ligaments was subjected to unlaxial mechanical testing in seven specimens. The alar ligaments had an in vitro strength of 200 N, and the transverse ligaments had an in vitro strength of 350 N. Histologic analysis revealed a mainly collagenous nature of these ligaments. Clinical evidence (broken odontoid processes) suggests that the transverse ligament is strong enough to withstand physiologic loads. The alar ligament, on the other hand, due to its lower strength and its axial direction of loading, might be prone to injury and therefore require stabilization of the appropriate vertebra more often than normally is assumed.
Synovial membrane and cartilage changes in experimental osteoarthrosis
Authors: Lukoschek M. , Schaffler M. B. , Burr D. B. , Boyd R. D. , Radin E. L. 
Published: February 2005

AbstractThe Hulth instability model was performed on 25 rabbit knee joints. Electron‐microscopic, light‐microscopic, and histomorphometric data demonstrated consistent chondrocyte alterations and cartilage destruction. The comparison between operated, sham, and control knees shows that surgical intervention without surgically induced instability is followed by changes in the synovial membrane and cartilage. The cartilage destruction is preceded by a synovial reaction, suggesting that the inflammatory response has an important role in the onset of cartilage damage in this model. The damage was more severe in the experimental knees, suggesting that mechanical instability is also a factor in cartilge destruction.
Loading‐related reorientation of bone proteoglycan in vivo. Strain memory in bone tissue?
Authors: Skerry T. M. , Bitensky L. , Chayen J. , Lanyon L. E. 
Published: February 2005

AbstractThe load‐carrying capacity of the skeleton is achieved and maintained as the result of a continued functional stimulus to the cell populations responsible for bone remodeling. Although some bone cells have been assumed to be influenced by the load‐induced changes in strain throughout the matrix, no evidence is available to indicate which cells are susceptible to such strain change or how such transient events provide a sustained influence on cell behaviour. In the present study, we showed that a short period of dynamic loading in vivo affects the orientation of proteoglycan within bone tissue. This reorientation declines only slowly, thus providing a persistent record of the tissue's recent strain history. Such a record has the ability not only to “capture” strain transients but also to “update” and “average” them. In this way, the bone cells could be presented with a sustained and coherent stimulus directly related to dynamic strain transients. These transients are the tissue's principal function variable.
Increased cAMP production after short‐term capacitively coupled stimulation in bovine growth plate chondrocytes
Authors: Brighton Carl T. , Townsend Peter F. 
Published: February 2005

AbstractGrowth plate chondrocytes from newborn calf costochondral junctions grown in monolayer were subjected to a capacitive AC signal of 500 V peak to peak (P‐P) at 60 kHz for 48 h and were analyzed for [3H]thymidine uptake. The stimulated chondrocytes showed a 130% greater uptake over unstimulated controls. Other newborn calf growth plate chondrocytes were stimulated at 500 V P‐P at 60 kHz for 2.5, 5.0, 10.0, and 20.0 min and were analyzed for cAMP. Chondrocytes stimulated for 2.5 and 5.0 min showed a 142.8% (p < 0.05) and 394.5% (p < 0.01) increase over controls, respectively. The chondrocytes stimulated for 10.0 and 20.0 min showed no significant difference from the controls. It is concluded that short‐term exposure of growth plate chondrocytes to an appropriate capacitively coupled field stimulates cAMP production, but longer‐term application of the electrical field is ineffective.
Calcium incorporation in cultured chondroblasts perturbed by an electromagnetic field
Authors: Norton Louis A. , Rovetti Leslie A. 
Published: February 2005

AbstractWe tested the hypothesis that electric perturbation influences 45Ca incorporation in extracellular matrix (ECM) of cartilage in vitro. Hypertrophic chondroblasts of tibial epiphyses (HC), sternum (SC), and skin fibroblasts (F) were cultured from chick embryos. HC, SC, and F cells were micromass seeded three times per week and maintained at 37.5°C with 5% CO2 for two weeks. Cultures were randomly designated control (C) or exposed (E) to a pulsed electromagnetic field (PEMF). A time course experiment of calcium incorporation for all cultured groups showed that 24 h of exposure produced the largest biological response in chondroblasts. Calcium incorporation required supplemental phosphate. Autoradiography data indicated that the calcium incorporation into macromolecules largely occurred in the ECM. 45Ca steady‐state perturbation was enhanced by Streptomyces hyaluronidase (SH) but not by testicular hyaluronidase (TH). 45Ca incorporation experiments tested the effects of phosphate, SH, TH, and PEMF alone and in various combinations on these cultures. Only PEMF or SH plus PEMF with phosphate enhanced 45Ca incorporation. Other experiments examined the effect of rotenone or freeze‐thawing on cells exposed to PEMF. PEMF plus freeze‐thaw enhanced calcium incorporation in HC only. PEMF appeared to cause disruption of the ECM, enhancing the probability of matrix calcification.
Response of cultured bone cells to a capacitively coupled electric field: Inhibition of cAMP response to parathyroid hormone
Authors: Brighton Carl T. , McCluskey William P. 
Published: February 2005

AbstractFetal rat calvarial bone cells grown in monolayers were exposed to a capacitively coupled electrical field of 2.62 mV/cm for 2.5–30 min. There was a 59% increase in cAMP concentration after electrical stimulation, compared with a 3615% increase after parathyroid hormone (PTH) adminstration. PTH administration after electrical stimulation resulted in less cAMP synthesis than following either electrical stimulation alone or PTH administration alone. When PTH administration was delayed for 30 min following cessation of the electrical stimulation, there was an inhibition in the cAMP response. This suggests that one possible mechanism of electrically induced osteogenesis is the desensitization of the bone cell to PTH. Since the effect of PTH is to increase bone resorption, desensitizing or blocking the effect of PTH at the bone cell level would result in a net increase in bone formation.
Sustained pressurization of polymethylmethacrylate: A comparison of low‐ and moderate‐ viscosity bone cements
Authors: Bean D. J. , Hollis J. M. , Woo S. L.‐Y , Convery F. R. 
Published: February 2005

AbstractThere is at present great uncertainty relating to the fixation of joint implants. The deficiencies of acrylic bone cement are well documented, but the limitations of cementless fixation are as yet imcompletely identified. The purpose of this study was to investigate the potential of sustained external pressurization to improve the mechanical characteristics of conventional acrylic bone cement. The effect of serially increasing sustained pressurization of two commerically available acrylic bone cements (Simplex‐P and LVC) was evaluated in human cadaver femora. A new method for determination of the shear strength of the bone‐cement interface in place of the traditional pushout tests was used. In this model, there was a significant increase in the bone‐cement interfacial shear strength with increasing pressure, but no difference in the shear strength was found between the two cements. At all pressure levels, the shear strength of the cement was greater than that previously reported. Increased cement penetration into the cortical bone was demonstrated with increasing pressure and low‐viscosity cement, but the extent of cement penetration did not correlate with the shear strength of the bone‐cement interface.
Ligament length relationships in the moving knee
Authors: Sidles John A. , Larson Roger V. , Garbini Joseph L. , Downey Daniel J. , Matsen Frederick A. 
Published: February 2005

AbstractThis article presents an investigation of potential ligament attachment sites for surgical reconstruction of the anterior and posterior cruciate ligaments as well as for the lateral extraarticular iliotibial band tenodesis. Our methodology was based on quantitative measurements of knee anatomy and motion in fresh cadavers, not on biomechanical modeling. Using computer search techniques, we located all the ligament insertion sites that were nearly isometric for motion of the intact knee.