bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biologic model of bone transport distraction osteogenesis and vascular response
Authors: DeCoster Thomas A. , Simpson A. H. R. W. , Wood Martin , Li Gang , Kenwright J. 
Published: February 2005

AbstractWe developed an experimental model in the rabbit of distraction osteogenesis through bone transport that closely corresponds to the clinical use of bone transport in humans. We also applied injection angiography to study the arterial response of a limb undergoing bone transport. This model includes a proximal osteotomy and bone transport to fill in a segmental tibial diaphyseal defect. Regenerate bone formed well in the gap that was created that trailed the transport segment, and slow healing at the docking site was observed, as seen in humans. The angiographic techniques clearly revealed, by radiography and anatomic dissection, the arterial response to bone transport. The results showed that the transport segment had an arterial supply after osteotomy and after transport. They also demonstrated an extensive increase in vessels in limbs that had undergone distraction osteogenesis, an observation made clinically in humans but not well demonstrated experimentally. Furthermore, angiography showed proximal stretching and distal kinking of the major artery of the leg. This model closely resembles distraction osteogenesis through bone transport in humans and definitively demonstrates that the transport segment can maintain blood supply and remain viable during the transport process. The results of this study provide a basis for further work on factors that enhance and interfere with successful bone transport in humans.
Intramedullary pressure and bone marrow fat extravasation in reamed and unreamed femoral nailing
Authors: Kröpfl Albert , Davies James , Berger Udo , Hertz Harald , Schlag Günther 
Published: February 2005

AbstractThis study was designed to investigate whether intramedullary pressure and embolization of bone marrow fat are different in unreamed compared with conventional reamed femoral nailing in vivo. In a baboon model, the femoral shaft was stabilized with interlocking nailing after a midshaft osteotomy. Intramedullary pressure was measured in the distal femoral shaft fragment at the supracondylar region. Extravasation of bone marrow fat was determined by the modified Gurd test (range: 0–5) with blood samples from the vena cava inferior. Data were monitored in eight unreamed and eight reamed intramedullary femoral nailing procedures. Intramedullary pressure increased in the unreamed group to 76 ± 25 mm Hg (10.1 ± 3.3 kPa) during insertion of 7‐mm nails and in the reamed group to 879 ± 44 mm Hg (117.2 ± 5.9 kPa) during reaming of the medullary cavity. Insertion of 9‐mm nails after the medullary cavity had been reamed to 10 mm produced an intramedullary pressure of 254 ± 94 mm Hg (33.9 ± 12.5 kPa) (p < 0.05). Fat extravasation in the unreamed group was recorded with a score of 2.9 ± 0.4 for the Gurd test during nailing with 7‐mm nails, whereas in the reamed group significantly more fat extravasation was noticed during the reaming procedures, with a score of 4.6 ± 0.1. Liberation of fat during insertion of 9‐mm nails after reaming was recorded with a score of 3.5 ± 0.4. In both groups, a positive correlation of fat extravasation with the rise in intramedullary pressure was found (reamed group: rs = 0.868: unreamed group: rs = 0.698), resulting in significantly less liberation of bone marrow fat in the unreamed stabilized group than in the reamed control group (p < 0.05). The data indicate that fat embolization during nailing procedures after femoral osteotomy increases with increasing intramedullary pressure and occurs in a lesser degree in unreamed than in reamed intramedullary femoral shaft stabilization.
Failure of partial cementation to achieve implant stability and bone ingrowth: A long‐term roentgen stereophotogrammetric study of tibial components
Authors: Ryd Leif , Hansson Ulrik , Blunn Gordon , Lindstrand Anders , Toksvig‐Larsen Sören 
Published: February 2005

AbstractThirty patients with gonarthrosis were operated on with the PCA primary total knee prosthesis and had the tibial component fixed to the bone by partial cementation. In the first two groups of patients, cementation was by a peripheral rim of high and low‐viscosity cement, respectively. In the third group, the pegs were cemented with the low‐viscosity cement. Follow‐up was performed with use of clinical parameters and roentgen stereophotogrammetric analysis. Clinically, the series was successful apart from a problem with tibial component wear, necessitating revision in five patients. At 8 years, the mean Hospital for Special Surgery score was 81 points. Venn‐diagram scores revealed four failures and three acceptable cases; the remaining cases were satisfactory. Apart from one loose patellar component, there was no mechanical loosening. Roentgen stereophotogrammetric analysis showed that the tibial components moved relative to the bone; this indicated fibrous tissue fixation. which was corroborated histologically in two patients. The objective, to achieve bone ingrowth, was thus not successfully met. Radiolucent lines were consistently seen, and their size correlated with the migration as measured by roentgen stereophotogrammetric analysis. Furthermore, five continuously migrating prostheses showed significantly larger radiolucent zones than the prostheses that migrated only initially, and they were less well bonded to the bone at 1 year. In conclusion, partial cementation does not appear to be a way to achieve bone ingrowth in porous‐coated implants under load.
Mechanical behavior of human trabecular bone after overloading
Authors: Keaveny Tony M. , Wachtel Edward F. , Kopperdahl David L. 
Published: February 2005

AbstractWith the etiology of osteoporotic fractures as motivation, the goal of this study was to characterize the mechanical behavior of human trabecular bone after overloading. Specifically, we quantified the reductions in modulus and strength and the development of residual deformations and determined the dependence of these parameters on the applied strain and apparent density. Forty cylindrical specimens of human L1 vertebral trabecular bone were destructively loaded in compression at 0.5% strain per second to strains of up to 3.0% and then immediately unloaded to zero stress and reloaded. (An ancillary experiment on more readily available bovine bone had been performed previously to develop this testing protocol.) In general, the reloading stress‐strain curve had a short initial nonlinear region with a tangent modulus similar to Young's modulus. This was followed by an approximately linear region spanning to 0.7% strain, with a reduced residual modulus. The reloading curve always approached the extrapolated envelope of the original loading curve. Percent modulus reduction (between Young's and residual), a quantitative measure of mechanical damage, ranged from 5.2 to 91.0% across the specimens. It increased with increasing plastic strain (r2 = 0.97) but was not related to modulus or apparent density. Percent strength reduction, in the range of 3.6–63.8%, increased with increasing plastic strain (r2 = 0.61) and decreasing apparent density (r2 = 0.23). The residual strains of up to 1.05% depended strongly on applied strain (r2 = 0.96). Statistical comparisons with previous data for bovine tibial bone lend substantial generality to these trends and provide an envelope of expected behavior for other sites. In addition to providing a basis for biomechanical analysis of the effects of damage in trabecular bone at the organ level, these findings support the concept that occasional overloads may increase the risk of fracture by substantially degrading the mechanical properties of the underlying trabecular bone.
Assessment of subchondral bone blood flow in the rabbit femoral condyle using the laser speckle method
Authors: Fukuoka Shinji , Hotokebuchi Takao , Terada Kazumasa , Kobara Nobuo , Fujii Hitoshi , Sugioka Yoichi , Iwamoto Yukihide 
Published: February 2005

AbstractThe laser speckle method is a new form of flowmetry that can obtain a two‐dimensional distribution of blood flow in tissue. This method is a noncontact, simple, and rapid technique that may aid in the diagnosis of osteonecrosis. We investigated whether the subchondral bone blood flow within the femoral condyles of rabbits could be measured by the laser speckle method. The hydrogen washout method was chosen as a comparison technique because of its ability to allow repetitive measurements of blood flow in various conditions in one rabbit and because of its realiability which already has been established. We simultaneously measured the bone blood flow in 20 femoral condyles of 10 rabbits with the laser speckle and hydrogen washout methods and found a significant correlation between the blood flow levels with use of these two methods. For the clinical application of the laser speckle method, we also investigated the influence of cartilage thickness on the measurements and the depth in the bone to which blood flow could be measured with this method. A cartilage thickness of 0.2 mm did not influence the measurement of the bone blood flow, and the depth in the bone to which the laser speckle method could be used was approximately 2 mm.
Mechanically induced calcium waves in articular chondrocytes are inhibited by gadolinium and amiloride
Authors: Guilak Farshid , Zell Richard A. , Erickson Geoffrey R. , Grande Daniel A. , Rubin Clinton T. , McLeod Kenneth J. , Donahue Henry J. 
Published: February 2005

AbstractChondrocytes in articular cartilage utilize mechanical signals from their environment to regulate their metabolic activity. However, the sequence of events involved in the transduction of mechanical signals to a biochemical signal is not fully understood. It has been proposed that an increase in the concentration of intracellular calcium ion ([Ca2+]i) is one of the earliest events in the process of cellular mechanical signal transduction. With use of fluorescent confocal microscopy, [Ca2+]i was monitored in isolated articular chondrocytes subjected to controlled deformation with the edge of a glass micropipette. Mechanical stimulation resulted in an immediate and transient increase in [Ca2+]i. The initiation of Ca2+ waves was abolished by removing Ca2+ from the extracellular media and was significantly inhibited by the presence of gadolinium ion (10 μM) or amiloride (1 mM), which have previously been reported to block mechanosensitive ion channels. Inhibitors of intracellular Ca2+ release (dantrolene and 8‐diethylaminooctyl 3,4,5‐trimethoxybenzoate hydrochloride) or cytoskeletal disrupting agents (cytochalasin D and colchicine) had no significant effect on the characteristics of the Ca2+ waves. These findings suggest that a possible mechanism of Ca2+ mobilization in this case is a self‐reinforcing influx of Ca2+ from the extracellular media, initiated by a Ca2+‐permeable mechanosensitive ion channel. Our results indicate that a transient increase in intracellular Ca2+ concentration may be one of the earliest events involved in the response of chondrocytes to mechanical stress and support the hypothesis that deformation‐induced Ca2+ waves are initiated through mechanosensitive ion channels.
Monitoring glycosaminoglycan replenishment in cartilage explants with gadolinium‐enhanced magnetic resonance imaging
Authors: Allen R. G. , Burstein D. , Gray M. L. 
Published: February 2005

AbstractWe previously devised a magnetic resonance imaging method that allows for the nondestructive and quantitative determination of glycosaminoglycan concentration in excised cartilage. The technique measures the concentration of the charged contrast agent Gd‐DTPA2− (gadolinium diethylenetriaminepentaacetic acid) equilibrated within cartilage, from which the tissue distribution of glycosaminoglycan can be calculated. The goals of our study were to determine the practicality of nondestructively monitoring glycosaminoglycan concentration in cartilage explants over a long‐term culture period and to determine if glycosaminoglycan could be restored to glycosaminoglycan‐depleted cartilage explants maintained in long‐term culture. To meet our objectives, we harvested bovine cartilage explants, treated them initially with trypsin to reduce the glycosaminoglycan concentration, and cultured them for as long as 8 weeks. Images depicting glycosaminoglycan concentration were calculated from magnetic resonance images acquired at selected intervals during the trypsinization process and the subsequent culture period. The results indicate that gadolinium‐enhanced magnetic resonance imaging can follow the reduction of glycosaminoglycan concentration over the course of enzymatic digestion and the replenishment of glycosaminoglycan over several weeks of culture and that cultured cartilage explants are capable of restoring glycosaminoglycan to 85% of its initial concentration. Of particular interest, samples cultured for 5 weeks indicated a depth dependence of glycosaminoglycan regeneration to values similar to the initial physiologic distribution. Thus, this magnetic resonance imaging method may be a very powerful means for exploring the spatial and temporal evolution of glycosaminoglycan in cartilage.
Coordinate upregulation of cartilage matrix synthesis in fibrin cultures supplemented with exogenous insulin‐like growth factor‐I
Authors: Fortier Lisa A. , Lust George , Mohammed Hussni O. , Nixon Alan J. 
Published: February 2005

AbstractThe addition of insulin‐like growth factor‐I to cartilage cultures is known to stimulate the synthesis of proteoglycan and type‐II collagen in explant and monolayer studies. The purpose of this study was to determine the effects of long‐term supplementation with insulin‐like growth factor‐I in chondrocytes cultured in fibrin discs as a preliminary investigation toin vivoapplication of chondrocyte/insulin‐like growth factor‐I/fibrin grafts to articular‐cartilage repair procedures. Chondrocyte‐fibrin cultures were maintained for 14 days, with insulin‐like growth factor‐I added at varying concentrations of 0, 10, 50, or 100 ng/ml medium. Cultures supplemented with 50 or 100 ng of growth factor/ml had increased levels of aggrecan and type‐IIB procollagen mRNA, and translation to aggrecan and type‐IIB collagen was confirmed by dye‐binding assay of total proteoglycan, type‐II collagen immunohistochemistry, and determination of collagen content by highperformance liquid chromatography. Maintenance of the chondrocyte phenotype during the 14 days of culture was confirmed by round cell morphology on routine staining, expression of type‐II procollagen mRNA onin situhybridization, evidence of production of pericellular type‐II collagen on immunocytochemistry, synthesis of large‐molecular‐size aggrecan monomer on CL‐2B column chromatography, and lack of appreciable message expression for type I or IIA collagen on Northern blot hybridization. Dose‐response effects of insulin‐like growth factor‐I on the expression of chondrocyte matrix constituents were most pronounced at 50 and 100 ng of growth factor per milliliter of medium. These data confirm that (a) culture of chondrocytes for extended periods in three‐dimensional cultures of fibrin maintains the chondrocyte phenotype and (b) supplementation with increasing concentrations of insulin‐like growth factor‐I enhances chondrocyte matrix synthesis and may provide a means to enhance chondrocyte phenotypic stability and function during transplantation grafting procedures.
Reduced bone stress as predicted by composite beam theory correlates with cortical bone loss following cemented total hip arthroplasty
Authors: Silva Matthew J. , Reed Karen L. , Robertson Douglas D. , Bragdon Charles , Harris William H. , Maloney William J. 
Published: February 2005

AbstractClinical and experimental evidence suggest that periprosthetic bone loss following total hip arthroplasty is caused in part by stress‐shielding. Changes in bone stress in the proximal femur following implantation can be estimated with use of composite beam theory. We hypothesized that the degree of stress‐shielding predicted by beam theory correlates with the magnitude of bone loss following cemented total hip arthroplasty. We analyzed cross sections from the proximal femur of 13 patients who had undergone unilateral cemented total hip arthroplasty. A matching implant was inserted contralaterally, and the cross‐sectional properties of the implant and bone and the bone density were determined. Bone loss was calculated on the basis of differences between contralateral (control) and ipsilateral (remodeled) sections and correlated to several beam‐theory parameters calculated from the control sections: implant rigidity, bone rigidity, ratio of implant to bone rigidity, and predicted decrease in bone stress. All parameters except implant rigidity were significantly correlated with bone loss (p < 0.05). Parameters that included implant and bone properties were more strongly correlated with bone loss than were those based on bone properties alone. The predicted decrease in bone stress explained 50‐60% of the variance in bone loss. The data also indicated that patients were not likely to lose substantial amounts of bone unless the reduction in bone stress exceeded a threshold value. Although limited by a small and heterogeneous sample, these results indicate that beam‐theory predictions correlate with the degree of femoral resorption and should be investigated further as a means to identify patients at high risk for bone loss.
Substance P and calcitonin gene‐related peptide expression at the extensor carpi radialis brevis muscle origin: Implications for the etiology of tennis elbow
Authors: Ljung Björn‐Ove , Forsgren Sture , Fridén Jan 
Published: February 2005

AbstractWith use of immunohistochemistry and antibodies to substance P and calcitonin gene‐related peptide, nerve fibers showing substance P‐like and calcitonin gene‐related peptide‐like immunoreactivity were demonstrated at the origin of the extensor carpi radialis brevis muscle in patients with tennis elbow (n = 6) and in healthy controls (n = 6). The nerve fibers were distributed in association with a subpopulation of small blood vessels and in nerve bundles but were not distributed in the tunica media‐adventitia junction of the arterioles. There were no inflammatory‐cell infiltrates and few solitary mast cells. The present study gives further evidence to previous suggestions that tennis elbow is not an inflammatory process in the sense of involving inflammatory cells. Frequent mechanical involvement affects sensory innervation, and substance P and calcitonin gene‐related peptide may have various important efferent effects, including microvascular leakage and local edema formation; therefore, the observations from this study constitute a morphological substrate for possible effects of substance P and calcitonin gene‐related peptide at the origin of the extensor carpi radialis brevis muscle.
Uniaxial yield strains for bovine trabecular bone are isotropic and asymmetric
Authors: Chang Wesley C. W. , Christensen Tennille M. , Pinilla Tania P. , Keaveny Tony M. 
Published: February 2005

AbstractAlthough evidence suggests that yield strains for trabecular bone are isotropic, i.e., independent of loading direction, decisive support for this hypothesis has remained elusive. To explicitly test whether yield strains for trabecular bone are isotropic, compressive and tensile yield strains of 51 specimens of bovine tibial trabecular bone (0.41 ± 0.08 g/cm3 [mean apparent density ± SD]) were measured without end artifacts in on‐axis (along the principal trabecular orientation) and off‐axis (30–40° oblique to on‐axis) orientations. Yield strains for the on‐axis and off‐axis orientations were similar in tension (0.80 ± 0.03% compared with 0.85 ± 0.04%, p = 0.21) and compression (0.97 ± 0.05% compared with 0.96 ± 0.07%, p > 0.99); as expected, modulus and strength depended on loading direction. When considered with an ancillary experiment on bovine tibial trabecular bone that showed yield strains to be similar between on‐axis and 90° off‐axis bone, these results firmly establish the isotropy of uniaxial yield strains for bovine tibial trabecular bone. This bone is of high density and has a strong, plate‐type, anisotropic architecture. Therefore, yield strains for uniaxial loading are expected to be isotropic, or nearly so, for other types of dense trabecular bone, although further work is required to confirm this and to establish this behavior for bone of lower density.
New segmental long bone defect model in sheep: Quantitative analysis of healing with dual energy X‐ray absorptiometry
Authors: den Boer Frank C. , Patka Peter , Bakker Fred C. , Wippermann Burkhard W. , van Lingen Arthur , Vink Ger Q. M. , Boshuizen Klaas , Haarman Henk J. Th. M. 
Published: February 2005

AbstractAn appropriate animal model is required for the study of treatments that enhance bone healing. A new segmental long bone defect model was developed for this purpose, and dual energy x‐ray absorptiometry was used to quantify healing of this bone defect. In 15 sheep, a 3‐cm segmental defect was created in the left tibia and fixed with an interlocking intramedullary nail. In seven animals, the defect was left empty for the assessment of the spontaneous healing response. In eight animals serving as a positive control, autologous bone grafting was performed. After 12 weeks, healing was evaluated with radiographs, a torsional test to failure, and dual energy x‐ray absorptiometry. The mechanical test results were used for the assessment of unions and nonunions. Radiographic determination of nonunion was not reliably accomplished in this model. By means of dual energy x‐ray absorptiometry, bone mineral density and content were measured in the middle of the defect. Bone mineral density was 91 ± 7% (mean ± SEM) and 72 ± 6% that of the contralateral intact tibia in, respectively, the autologous bone‐grafting and empty defect groups (p = 0.04). For bone mineral content, the values were, respectively, 117 ± 18 and 82 ± 9% (p = 0.07). Torsional strength and stiffness were also higher, although not significantly, in the group with autologous bone grafting than in that with the empty defect. Bone mineral density and content were closely related to the torsional properties (r2 ranged from 0.76 to 0.85, p ⩽ 0.0001). Because interlocking intramedullary nailing is a very common fixation method in patients, the newly developed segmental defect model has clinical relevance. The interlocking intramedullary nail provided adequate stability without implant failure. This model may be useful for the study of treatments that affect bone healing, and dual energy x‐ray absorptiometry may be somewhat helpful in the analysis of healing of this bone defect.