bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reimplantation of growth plate chondrocytes into growth plate defects in sheep
Authors: Foster B. K. , Hansen A. L. , Gibson G. J. , Hopwood J. J. , Binns G. F. , Wiebkin O. W. 
Published: February 2005

AbstractDefects in growth plates due to trauma, infection, or genetic causes can result in bone formation across the defect, bridging the epiphysis and metaphysis, resulting in growth arrest and limb deformation. We have investigated the capacity of implanted chondrocyte cultures to prevent this process. Sheep growth plate chondrocytes were isolated, and after culture at high density produced easily manipulated cartilaginous disc. The tissue was implanted into growth plate defects produced in lambs and the response was assessed histologically. Following implantation, cultures continued to proliferate and maintain a cartilage‐like matrix. 8 to 12 weeks, hypertrophic maturation, chondrocyte columnation, and associated endochondral calcification were observed. Culture implantation was always associated with local immune inflammatory feaction, which continued throughout the course of investigation. Cellular survival was variable and resulted in the presence of viable implants as well as residual cartilage matrix devoid of chondrocytes; however, implanted chondrocyte discs always prevented bone bridge formation. These findings encourage the expectation that cultured chondrocytes may provide a useful replacement for the inert interpositional materials currently used in the treatment used in the treatment of growth arrest. The potential of this technique for growth plate replacement, however, requires a more predictable rate of implant survival. The likely reasons for implant loss are discussed.
Fatigue fractures in thoroughbred racehorses: Relationships with age, peak bone strain, and training
Authors: Nunamaker D. M. , Butterweck D. M. , Provost M. T. 
Published: February 2005

AbstractThe North American Thoroughbred racehorse was chosen as a model to study the pathogenesis of fatigue failure of bone. This species has a high incidence of spontaneous fatigue failure of bone (bucked shins) during its early training. In vivo strain gauge studies of the third metacarpal bone o four young racehorses running at racing speeds showed high principal compressive strains [−4,841 ± 572 (SD) microstrain] while two older horses had lower principal compressive strains (−3,317 microstrain measured at racing speed, −3,250 microstrain extrapolated from a slower speed run). Previously reported intertial property measurements of the third metacarpal bone were related to the diffeence in bone strains seen in young and older horses. The high strains on the surface of the third metacarpal bone associated with young horses in training may lead to high strain, low cycle fatigue. The changing shape of the third metacarpal bone during maturation may be consistent with the lower strains recorded during high speed exercise in theo lder animals. This phenomenon may allow for the accumulation of additional strain cycles in older animals beore failure occurs.
Combined treatment with cyclosporin A and cortisone acetate minimizes the adverse bone effects of either agent alone
Authors: Movsowitz C. , Schlosberg M. , Epstein S. , Ismail F. , Fallon M. , Thomas S. 
Published: February 2005

AbstractAlthough cyclosporin A (CsA) and cortisone acetate (CRT) adversely affect bone, their combined effect on bone is unknown. Sprague Dawley rats were therefore administered either vehicle or CsA (7.5 mg/kg/day) by gavage and saline or CRT (2 mg/100 mg/day) by s.c. injection for 28 days. Group A received vehicle plus saline, group B CsA plus saline, group C vehicle plus CRT, and group D CsA/CRT. Serial bloods were sampled over a 28‐day period for ionized calcium (Ca), PTH, 1,25 dihydroxyvitamin D (1,25(OH)2D), and bone gla protein (BGP osteocalcin) and tibia were examined on day 28 for histomorphometry. Results were compared with group A. Ca and PTH levels in groups B, C, and D were similar to those in group A during the study period. Group B had lower body weights, elevated levels of BGP, and an increase in 1,25(OH)2D. Group C developed weight loss and a decrease in BGP and 1,25(OH)2D. Group D had weight loss, BGP levels between those of group A and group C, and 1,25(OH)2D values similar to group A. Bone histomorphometry revealed high turnover osteopenia in group B and hyperostosis in group C with a decrease in bone formation and osteoclastlike cells. Combination therapy returned these to control values. In conclusion, the adverse effects of either CsA or CRT on bone in rats are minimized by combined therapy.
An approach for time‐dependent bone modeling and remodeling—theoretical development
Authors: Beaupré G. S. , Orr T. E. , Carter D. R. 
Published: February 2005

AbstractA time‐dependent approach for emulating bone modeling and remodeling in response to the daily loading history is presented. We postulate that genotype, systemic metabolic conditions, and local tissue interactions establish the level of local tissue mechanical stimulation (attractor state) appropriate for the maintenance of bone tissue. The net daily rate of apposition or resorption on a bone surface is determined by the difference between the actual stimulus and the tissue attractor state and can be modulated by other biologic factors. In calculating the net change in local bone apparent density, the technique takes into account the bone surface area available for osteoblastic and osteoclastic activity. Endosteal, periosteal, haversian, and cancellous bone modeling and remodeling are thereby treated in a consistent, unified fashion.
Electromagnetic effects on bone formation at implants in the medullary canal in rabbits
Authors: Spadaro J. A. , Albanese S. A. , Chase S. E. 
Published: February 2005

AbstractThis experiment was aimed at illuminating the relationship between electromagnetic and mechanical stimuli of bone formation when present simultaneously. Movable and stationary intramedullary wire implants were studied in rabbits treated with a pulsing electromagnetic field (PEMF) 4 h/day for 3 weeks, and were compared with identical control animals without PEMF. Trabecular bone formed routinely at spontaneously movable implants, but not at stationary ones. On average, PEMF‐treated movable implants in the femur induced 44% more bone than untreated movable implants. Also, in the PEMF‐treated femora, a 22% enlargement of the area of the medullary canal was observed compared with no‐field controls. In the tibia, these effects were weak or nonexistent. The PEMF used did not induce bone at stationary implants, suggesting that under these conditions it is not a primary trigger in vivo.
Osteoarthrosis induced by intra‐articular hydrogen peroxide injection and running load
Authors: Kaiki Genkyo , Tsuji Haruo , Yonezawa Takanobu , Sekido Hiromichi , Takano Takashi , Yamashita Shinichiro , Hirano Norikazu , Sano Akimi 
Published: February 2005

AbstractOsteoarthrosis of the rat knee joint was induced successfully by intra‐articular injection of 2% hydrogen peroxide (H2O2) and running load. In the group receiving two injections of physiological saline with running load, no histological osteoarthrotic knees were developed up to 8 weeks after the injection. In the group receiving two 2% H2O2 injections and running load, advanced osteoarthrosis occurred in all knees 8 weeks after the first injection, and the Mankin's score of osteoarthrotic knees appeared to be higher than the group receiving two 2% H2O2 injections without running load (p < 0.004, Kruskal‐Wallis H test). In the rats receiving a single 2% H2O2 injection with running load and a vitamin E‐enriched diet, the inhibitory effect of vitamin E on the development of osteoarthrosis was statistically significant compared to the regular diet group (p < 0.05, Wilcoxon rank test).
Visualization of living terminal hypertrophic chondrocytes of growth plate cartilage in situ by differential interference contrast microscopy and time‐lapse cinematography
Authors: Farnum Cornelia E. , Turgai John , Wilsman Norman J. 
Published: February 2005

AbstractThe functional unit within the growth plate consists of a column of chondrocytes that passes through a sequence of phases including proliferation, hypertrophy, and death. It is important to our understanding of the biology of the growth plate to determine if distal hypertrophic cells are viable, highly differentiated cells with the potential of actively controlling terminal events of endochondral ossification prior to their death at the chondro‐osseous junction. This study for the first time reports on the visualization of living hypertrophic chondrocytes in situ, including the terminal hypertrophic chondrocyte. Chondrocytes in growth plate explants are visualized using rectified differential interference contrast microscopy. We record and measure, using time‐lapse cinematography, the rate of movement of subcellular organelles at the limit of resolution of this light microscopy system. Control experiments to assess viability of hypertrophic chondrocytes include coincubating organ cultures with the intravital dye fluorescein diacetate to assess the integrity of the plasma membrane and cytoplasmic esterases. In this system, all hypertrophic chondrocytes, including the very terminal chondrocyte, exist as rounded, fully hydrated cells. By the criteria of intravital dye staining and organelle movement, distal hypertrophic chondrocytes are identical to chondrocytes in the proliferative and early hypertrophic cell zones.
A model of Staphylococcus aureus bacteremia, septic arthritis, and osteomyelitis in chickens
Authors: Daum Robert S. , Davis W. Hodges , Farris K. Barton , Campeau Richard J. , Mulvihill Denise M. , Shane Simon M. 
Published: February 2005

AbstractWe studied the occurrence, magnitude, and kinetics of bacteremia and the resultant osteomyelitis and septic arthritis in an avian model of Staphylococcus aureus infection. Thirty‐day‐old male broiler chicks were inoculated i.v. with 105, 106, or 107 cfu of strain Duntravis, a β‐hemolytic, coagulaseproducing, capsular type 8 isolate from the synovial fluid of a 2‐year‐old black boy. Bacteremia occured in 80%, 90%, and 100% of animals inoculated with 105, 106, or 107 cfu, respectively. The magnitude of bacteremia in surviving, bacteremic animals increased for 96 hours after inoculation and then decreased after a plateau phase. Osteomyelitis and septic arthritis occurred only in chicks that were continuously bacteremic. The occurrence of osteomyelitis was uniform among continuously bacteremic animals and developed 1 to 23 hours after inoculation. Chickens are susceptible to systemic infections with S. aureus. Bacteremia, osteomyelitis, and septic arthritis may be induced in healthy chickens without prior manipulations that depress their resistance.
Evaluation of a microcomputed tomography system to study trabecular bone structure
Authors: Kuhn J. L. , Goldstein S. A. , Feldkamp L. A. , Goulet R. W. , Jesion G. 
Published: February 2005

AbstractA new microcomputed tomography (micro‐CT) system and thresholding procedure was evaluated as a tool for nondestructive analysis of trabecular bone. Images of 6‐mm trabecular bone cubes acquired from the micro‐CT system were compared with optical images of corresponding histologic sections to determine the accuracy of representation. The stereologic measures of bone volume fraction (Pp) and trabecular plate densty (PL) were used to quantify the comparisons. The results showed that the micro‐CT measures of Pp were not significantly different from those measured from histologic sections and therefore were very accurate. Measures of PL were different by approximately 14%, which translated into discrepancies in trabecular plate thicknesses of about 19 μm. This difference was significantly correlated to the microstructural characteristics of the specific specimen scanned. The precision of both measurements was excellent.
Effects of retinacular release and tibial tubercle elevation in patellofemoral degenerative joint disease
Authors: Lewallen David G. , Riegger Chery L. , Myers Elizabeth R. , Hayes Wilson C. 
Published: February 2005

AbstractRelease of the patellar retinaculum and tibial tubercle elevation have both been advocated for the treatment of patellofemoral degeneration. Questions remain, however, regarding the magnitude and predictability of such effects in diseased joints. Using cadaver knee joints exhibiting a range of patellofemoral cartilage degeneration, we investigated the effects on joint contact pressures on release of the patellar retinaculum, followed by tibial tubercle elevations of 1.25 and 2.5 cm. Retinacular release failed to alter the joint‐loading parameters significantly. Tibial tubercle elevation reduced the patello‐femoral joint contact area and contact force, but failed to cause a consistent change in contact pressure. Tibial tubercle elevation also caused a migration of the joint contact area superolaterally on the retropatellar surface. This migration occurred in conjunction with ventral tilting of the inferior pole of the patella as the tubercle was elevated, suggesting that significant changes in joint kinematics may result from this procedure.
The effect of porous coating processing on the corrosion behavior of cast Co–Cr–Mo surgical implant alloys
Authors: Jacobs J. J. , Latanision R. M. , Rose R. M. , Veeck S. J. 
Published: February 2005

AbstractThe manufacture of porous coated cobalt‐based surgical implant alloys requires sintering–a high temperature process above the incipient melting temperature of this alloy system. The metallurgical changes produced by the high temperature sinter cycle consist of dissolution of interdendritic carbides, massive precipitation of lamellar carbide eutectic phases at grain boundaries, localized porosity from incipient melting that is not completely eliminated by subsequent hot isostatic pressing, and grain growth in fine‐grained meterials. These microstructural changes, which are known to affect the mechanical properties, do not affect the static in vitro localized and generalized corrosion behavior of the bulk material as determined by anodic polarization measurements in a buffered saline environment and direct examination by scanning electron and optical microscopy. Additionally, cast Co‐Cr‐Mo surgical implant alloys are found to be immune to crevice corrosion (in the absence of mechanical fretting) in the saline environment studied. The hystertic component of the anodic polarization curve is not due to crevice corrosion; rather, as suggested by the electrochemical tests and Auger spectroscopy, the hysteresis is due to redox reactions in the chromium‐rich surface layer.
The effects of hydrostatic pressure on matrix synthesis in articular cartilage
Authors: Hall A. C. , Urban J. P. G. , Gehl K. A. 
Published: February 2005

AbstractThe direct effects of hydrostatic pressure on matrix synthesis in articular cartilage can be studied independently of the other factors that change during loading. We have found that the influence of hydrostatic pressure on incorporation rates of 35SO4 and [3H]proline into adult bovine articular cartilage slices in vitro depends on the pressure level and on the time at pressure. Pressures in the “physiological” range (5–15 MPa) applied for 20s or for 5 min could stimulate tracer incorporation (30–130%) during the following 2 h, but higher pressures (20–50 MPa) had no effect on incorporation rates. The degree of stimulation in cartilage obtained from different animals was found to vary; in some animals none was seen. Stimulation also varied with position along the joint. Physiological pressures (5–10 MPa) applied continuously for the 2‐h incubation period also stimulated incorporation rates, but pressures >20 MPa always produced a decrease that was related to the applied pressure and that was reversible. These results suggests that the hydrostatic pressure that occurs during loading is a signal that can stimulate matrix synthesis rates in articular cartilage.
Demineralized allogeneic bone matrix for cartilage repair
Authors: Dahlberg Leif , Kreicbergs Andris 
Published: February 2005

AbstractWe tested the chondrogenic potential of demineralized allogeneic bone matrix (DABM) in the repair of osteochondral defects. In 42 adult rabbits, a 5‐mm2 or 15‐mm2 defect was created bilaterally in the intercondylar groove of distal femur. DABM was inserted directly in 37 defects, whereas in 35 it was inserted after previous placement in muscle for 4, 16, or 19 days. Another 12 defects were left empty, serving as controls. Subgroups of animals were killed at 6, 12, 18, and 26 weeks. The distal femora were excised and prepared for histologic evaluation in hematoxylin‐eosin and toluidine blue. Cartilage‐like repair tissue was observed in the majority of defects. However, there was a great variability in the experimental groups without any clear relationship to type of DABM implant, defect size, or postoperative time. Even individual knees exhibited varying stages of cartilage differentiation. Overall, DABM placed in muscle for 19 days appeared to yield the best repair of the defects. The most consistent findings of the present study were bone formation in the marrow of distal femur and, notably, the absence of bone differentiation toward the joint surface. Hence, it seems that the synovial environment prevents bone formation otherwise induced by DABM in vascular tissue. Although tissue formed in articular defects supplemented with DABM is of cartilaginous differentiation, which is retained over time, it is of highly variable quality. Hence, the described approach has to be optimized before it can be applied for the purpose suggested.
Histochemical and ultrastructural observations on brown degeneration of human intervertebral disc
Authors: Ishii Tsutomu , Tsuji Haruo , Sano Akimi , Katoh Yoshiharu , Matsui Hisao , Terahata Nobuo 
Published: February 2005

AbstractThirty‐eight fresh human intervertebral discs collected during anterior interbody fusion surgery were histochemically and ultrastructurally analyzed for pigments. Macroscopically, five stages of degeneration were classified according to the color, fibrosis, and fragility of the nucleus pulposus of the discs. In order to demonstrate lipofuscin granules, specimens were subjected to special staining procedures, including carbol fuchsin lipofuscin stain, the Schmorl's reaction, and autofluorescence. Lipofuscin granules were distributed from the inner layer of the annulus fibrosus to the nucleus pulposus. Such granules were numerous in cases of slight or severe degeneration, whereas fewer granules were found in cases of moderate degeneration. However, the stage of macroscopic degeneration of the intervertebral disc did not necessarily correlate with the incidence of lipofuscin granules. By ultrastructural observation, the morphological features of the components of the intervertebral disc and the ultrastructure of the lipofuscin granule were clarified. The ultrastructure of the “brown degeneration” disc exhibited markedly increased amorphous electron‐dense bodies located among collagen fibrils in the matrix.
[99mTc]diphosphonate uptake and hemodynamics in arthritis of the immature dog knee
Authors: Hansen Ebbe Stender , Søballe Kjeld , Henriksen Tine Brink , Hjortdal Vibeke Elisabeth , Bünger Cody 
Published: February 2005

AbstractThe relationship between [99mTc]diphosphonate uptake and bone hemodynamics was studied in canine carrageenan‐induced juvenile chronic arthritis. Blood flow was determined with microspheres, plasma and red cell volumes were measured by labeled fibrinogen and red cells, and the microvascular volume and mean transit time of blood were calculated. Normal femoral epiphyses had lower central and higher subchondral blood flow and diphosphonate uptake values. Epiphyseal vascular volume was uniform, resulting in a greater transit time of blood centrally. In arthritis, blood flow and diphosphonate uptake were increased subchondrally and unaffected centrally, while epiphyseal vascular volume was increased throughout, leading to prolonged transit time centrally. The normal metaphyses had low blood flow and diphosphonate uptake values in cancellous bone and very high values in growth plates, but a large vascular volume throughout. The mean transit time therefore was low in growth plates and high in adjacent cancellous bone. Arthritis caused decreased blood flow and diphosphonate uptake in growth plates but increased vascular volume and transit time of blood. Diphosphonate uptake correlated positively with blood flow and plasma volume and negatively with red cell volume in a nonlinear fashion. Thus, changes in diphosphonate uptake and microvascular hemodynamics occur in both epiphyseal and metaphyseal bone in chronic synovitis of the immature knee. The [99mTc]diphosphonate bone scan seems to reflect blood flow, plasma volume, and red cell volume of bone.
Necrosis of the capital femoral epiphysis and medial approaches to the hip in piglets
Authors: Fisher Edward H. , Beck Pul A. , Hoffer M. Mark 
Published: February 2005

AbstractIn an attempt to produce necrosis of the femoral head, the medial femoral circumflex vessels were disrupted in 13 normal piglet hips through a medial approach. Femoral heads were recovered 3–6 months (average 4.2 months) postoperatively. None of these hips showed gross, radiographic, or microscopic evidence of necrosis. This demonstrates that necrosis, which may occur after the medial approach in the hip of a child, is not due to the direct damage to the medial femoral circumflex vessels.
Anterior and posterior internal fixation of vertical shear fractures of the pelvis
Authors: Stocks Gregory W. , Gabel Gerard T. , Noble Philip C. , Hanson Gregory W. , Tullos Hugh S. 
Published: February 2005

AbstractA laboratory study was undertaken to evaluate the effectiveness of alternative methods of fixation of unilateral vertical shear fractures of the pelvis. Prior to experimental testing, a biomechanical analysis was performed to estimate the forces that displace the hemipelvis in the presence of two different patterns of injury: an interforaminal sacral fracture and a disruption of the sacroiliac joint. These lesions were then experimentally created in five unembalmed human pelvises and sequentially fixed with an external Hoffmann frame alone, a Hoffmann frame with sacral bars, or sacral bars with either one or two bone plates placed across the symphysis pubis. Each pelvis/fixator system was mechanically tested by loading along the direction of the resultant muscle force predicted by the biomechanical analysis. During loading the proximal migration of the ilium was continuously recored with a transducer. At intervals during loading, the three‐dimensional displacement of the detached hemipelvis at the pubic symphysis was also measured using a stereophotographic technique. With both the sacral frature and the sacroiliac disruption, the addition of posterior sacral rods substantially increased the strength and rigidity of fixation provided by the Hoffmann fixation frame alone (p < 0.01). In speciments with a sacral fracture, the use of anterior plates with posterior rods restored 65–71% of the strength of the intact pelvis, in comparison with 46% observed with the combination of sacral rods with an anterior Hoffmann frame (p < 0.01). All of the methods of fixation evaluated in this study were less successful in stabilizing the sacroiliac distruption. In this case there was no significant difference between the fixation achieved with one or two anterior bone plates or a Hoffmann frame placed anteriorly in combination with sacral rods placed posteriorly. In both patterns of injury treated with posterior sacral rods, the use of two anterior base plates led to no significant enhancement of the strength or the rigidity of fixation compared with one anterior plate alone.