bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of ascorbic acid on the metabolism of rat calvarial bone cells in vitro
Authors: Spindler Kurt P. , Shapiro David B. , Gross Stephen B. , Brighton Carl T. , Clark Charles C. 
Published: February 2005

AbstractAddition of 50 μg/ml sodium ascorbate to confluent cultures of isolated rat calvarium bone cells resulted in a 21% increase in DNA production, a 50–60% increase in incorporation of [14C]proline into collagenous and noncollagenous proteins, and a 200% increase in alkaline phosphatase activity; under identical conditions, [35S]sulfate incorporation into proteoglycans (glycosaminoglycans) was not affected. These results suggest that ascorbate may be important in maintaining or stimulating the osteogenic phenotype of normal bone cells.
Quantitative histologic study of the influence of spinal instrumentation on lumbar fusions: A canine model
Authors: Farey Ian D. , McAfee Paul C. , Gurr Kevin R. , Randolph Mark A. 
Published: February 2005

AbstractHistomorphometric and microradiographic studies were performed on 28 beagle hounds 1 year of age, followed up for 6 months after an L5–L6 anterior and posterior spinal destabilization procedure—Group I (n = 7),destabilizedsurgical controls, Group II (n = 7),posterolateral bone graftingafter destabilization; Group III (n = 7),Harrington rodinstrumentation and posterolateral bone grafting after destabilization; and Group IV (n = 7),Luque instrumentation, and bone grafting after destabilization. Six months postoperatively, device‐related osteoporosis occurred in spines treated with spinal instrumentation. Within the L5 vertebral body the mean trabecular width was less for the two groups with instrumentation (Groups III and IV) compared with the two groups without instrumentation (Groups I and II) (p < 0.001). The bone formation rate [mm3/(mm3× year)] × 103, which is based on the mean distance between sequenced fluorochrome labels, for Group I (destabilized, nonfused, noninstrumented dogs) was more than twice that of the other three groups, which were all equivalent (p < 0.05).Clinical relevance: Stress shielding, or more correctly, device‐related osteoporosis, probably can occur within vertebrae in response to rigid spinal instrumentation. However, the overall mechanical properties of vertebrae underlying spinal instrumentation are probably not at increased risk of fracture because the increase in cross‐sectional area of the vertebra and incorporated fusion mass more than compensate for the loss of volumetric bone density.
Biomechanics of the rabbit cervical spine as a function of component transection
Authors: Wetzel F. Todd , Panjabi Manohar M. , Pelker Richard R. 
Published: February 2005

AbstractThe rabbit cervical spine in the form of the functiona spinal unit was tested in a manner analogous to that used to study human functional spinal units. Anatomies and biomechanical similarities and differences with the human were demonstrated. The rabbit cervical spine failed abruptly after a welldefined series of anterior or posterior segmental injuries. However, up to the failure point, the rabbit cervical spine exhibited an increased range of motion after each segmental injury. The results of this study were used to develop an in vivo model for the study of spinal injury in subsequent projects.
Hardness, an indicator of the mechanical competence of cancellous bone
Authors: Hodgskinson R. , Currey J. D. , Evans G. P. 
Published: February 2005

AbstractHardness and calcium content in compact bone are strongly related. Variation in Young's modulus is produced mainly by variations in mineralisation. Therefore, there should be a relationship between hardness and Young's modulus. We demonstrate this. The calcium content of cancellous bone and adjacent compact bone in several species shows little difference, the cancellous bone having ∼10% less calcium. The hardness of cancellous bone in Bos is ∼12% less than that of adjacent compact bone, and the calcium is ∼2% less. These lines of evidence make it unlikely that the Young modulus of cancellous bone material is much different from that of compact bone. Similar evidence suggests that the yield stress of cancellous bone is similar to that of adjacent compact bone.
Material properties of the normal medial bovine meniscus
Authors: Proctor C. S. , Schmidt M. B. , Whipple R. R. , Kelly M. A. , Mow V. C. 
Published: February 2005

AbstractThe intrinsic compressive and tensile properties of normal bovine medial menisci were measured, and the variations in these properties with respect to the structural organization of the tissue and test specimen location were examined. Using a confined compression experiment, the compressive aggregate modulus and permeability of the meniscus were determined. The permeability of the tissue was also compared with the permeability as measured experimentally using a direct permeation experiment. Deep posterior specimens are significantly stiffer in compression than deep anterior and central‐anterior specimens, while deep anterior specimens are significantly less stiff than deep posterior and central‐posterior sepcimens. Posterior specimens have a significantly higher average water content. In addition, the permeability of the bovine meniscus was found to be about one‐tenth that of bovine articular cartilage. The tensile stiffness of meniscal tissue was determined from constant strain rate uniaxial tension tests. To asses the directional variations in the tensile properties, specimens were obtained from the circumferential and radial orientations. The results indicate that the femoral surface of the meniscus is isotropic in tension, while specimens from within the meniscus are anisotropic—the circumferential specimens are much stiffer than the radial specimens. Furthermore, circumferential posterior specimens from the interior of the meniscus are significantly stiffer than similar anterior specimens. Layer inhomogeneities in the tensile properties with respect to distance from the femoral surface are also present.
Transplantation of the rabbit medial collateral ligament. II. Biomechanical evaluation of frozen/thawed allografts
Authors: Sabiston P. , Frank C. , Lam T. , Shrive N. 
Published: February 2005

AbstractThis study was designed to test the mechanical behavior of a frozen/thawed bone‐medial collateral ligament (MCL)‐bone allograft in a rabbit model and to compare allograft behavior with contralateral unoperated ligaments as well as a group of normal bone‐ligament‐bone preparations prior to freezing. Twenty‐five mature rabbits received similarly frozen bone‐MCL‐bone allografts and were subsequently allowed to heal without immobilization in groups of five for 3, 6, 12, 24, or 48 weeks after transplantation. A series of biomechanical tests was performed on each allograft, contralateral, and external normal control ligament. Results demonstrated that allografts were significantly tighter than controls at 3 weeks and they remained tight over time. All allografts, however, had inferior structural and material behaviors as compared with controls. Allograft insertional bone and substance deteriorated to about 60% of contralateral strength at 12 and 48 weeks. Bony insertions became the most common site of graft weakness. Both stress at failure and the elastic modulus of allograft substance similarly reached a plateau at those intervals, but at about 30% of contralateral controls. Cyclic and load relaxation properties of allografts, on the other hand, did not deteriorate and were, in fact, indistinguishable from contralateral and normal values at 48 weeks. Comparison with a series of fresh autografts suggests that, with the exception of this viscoelastic recovery, allografts were mechanically inferior to autografts in their healing at the intervals tested. Collectively, these results suggest that allograft MCL healing in this composite model is dynamic but slow, featuring changes in bone and soft tissue over the first year after transplantation. Although “viable” and vascular, allografts have not normalized mechanically and, in fact, appear to have reached a new equilibrium whereby properties are neither improving nor deteriorating. Despite this apparent equilibrium, the trend for some viscoelastic recovery provides hope that allografts may have further potential for improvement. Longer‐term studies of MCL allograft mechanical behaviors are clearly required.
Excursion of the flexor digitorum profundus tendon: A kinematic study of the human and canine digits
Authors: Horibe S. , Woo S. L‐Y. , Spiegelman J. J. , Marcin J. P. , Gelberman R. H. 
Published: February 2005

AbstractThe most common problem following primary flexor tendon repair is the failure of the tendon apparatus to glide, secondary to the formation of adhesions. Early motion following tendon repair has been shown to be effective in reducing adhesions between the tendon and the surrounding sheath. Therefore, it is important to determine the amount of flexor tendon excursion along the digit during joint motion. In this study, the excursion between the flexor digitorum profundus (FDP) tendon and the sheath was examined in both human and canine digits. Based on roentgenographic measurements and joint kinematic analysis, the motion of the bones, the FDP tendon, and the sheath were measured with respect to joint rotations. It was found that the canine flexor tendon apparatus behaved similarly to that of the human for the motions studied. The amount of tendon excursion was very small in regions distal to the joint in motion (approximately 0.1 mm/10° of joint rotation). There was little displacement of the sheath (0.2–0.3 mm), except at the metacarpal joint region during metacarpophalangeal (MCP) joint motion and at the proximal interphalangeal (PIP) joint region during PIP joint motion. Tendon excursion relative to the tendon sheath was the largest in zone II during PIP joint rotation (1.7 mm/10° of joint rotation). These results suggest that PIP joint motion may be most effective in reducing adhesions following tendon repair in zone II.
Vasoactive substances in subchondral bone of the dog knee
Authors: Holm Ida Elisabeth , Ewald Henrik , Bülow Jens , Bünger Cody 
Published: February 2005

AbstractThe purpose of the present study was to investigate regulatory mechanisms for subchondral bone blood flow. A model including elevation of joint cavity pressure in the immature dog knee was applied. The role of prostaglandins in bone blood flow regulation was indirectly examined by indomethacin blockade. In six puppies, both venous tamponade of the joint cavity [50% of the mean arterial blood pressure(MAP)] and arterial tamponade (150% of MAP) resulted in a significant increase in the intraosseous pressure of the distal femoral epiphyses (p < 0.05). During venous tamponade no changes were registered in pO2, pCO2, pH, potassium, and lactate in blood withdrawn from the distal femoral epiphyses. Arterial tamponade resulted in hypoxia, a decrease in pH, and increased lactate. Inhibition of the prostaglandin synthesis did not alter this response pattern. Thus, the present study suggests the presence of a regulatory mechanism for subchondral bone blood flow since venous tamponade did not significantly alter intraosseous gas tensions, pH, lactate, or potassium in spite of elevated venous outlet resistance. The study does not allow any conclusion as to the exact nature of the regulatory mechanism, but local metabolic regulation is likely to be involved as indicated by accumulation of vasoactive substances at higher tamponade levels. Prostaglandins are probably of minor importance in this regulation.
Effects of proteoglycan extraction on the tensile behavior of articular cartilage
Authors: Schmidt Mary Beth , Mow Van C. , Chun Lawrence E. , Eyre David R. 
Published: February 2005

AbstractWe undertook an interdisciplinary biomechanical and biochemical study to explore the extent and manner in which the total pool of proteoglycans influences the kinetic and static behavior of bovine articular cartilage in tension. Two biomechanical tests were used: (a) the viscoelastic creep test and (b) a slow constant‐rate uniaxial tension test; and two enzymatic proteoglycan extraction procedures were used: (a) chondroitinase ABC treatment and (b) a sequential enzymatic treatment with chondroitinase ABC, trypsin, and Streptomyces hyaluronidase. We found that the viscoelastic creep response of all cartilage specimens may be divided into two distinct phases: an initial phase (< 15 s), characterized by a rapid increase in strain following load application, and a late phase (15 s < t < 25,000 s), characterized by a more gradual increase in strain. A major finding of this study is that the kinetics of the creep response is greatly influenced by the glycosaminoglycan content of the tissue. For untreated and control specimens, the initial response comprises about 50% of the total strain, while for chondroitinase ABC and sequentially extracted specimens, the initial response comprises up to 83% of the total strain. Furthermore, most untreated and control specimens did not reach equilibrium within the 25,000 s test period, while enzymatically digested specimens often reached equilibrium in less than 100 s. Thus, we conclude that through their physical restraints on collagen, the bulk of proteoglycan present in the tissue acts to retard fibrillar reorganization and alignment under tensile loading, thereby effectively preventing sudden extension of the collagen network. In contrast, the results of our slow constant‐rate uniaxial tension experiment show that essentially complete extraction of proteoglycan glycosaminoglycans does not affect the intrinsic tensile stiffness and strength of cartialge specimens or the collagen network in a significant manner. Hence, an important function of the bulk proteoglycans (i.e., the large aggregating type) in cartilage is to retard the rate of stretch and alignment when a tensile load is suddenly applied. This mechanism may be useful in protecting the cartilage collagen network during physiological situations, where sudden impact forces are imposed on a joint.
Acidic fibroblast growth factor (aFGF) injection stimulates cartilage enlargement and inhibits cartilage gene expression in rat fracture healing
Authors: Jingushi S. , Heydemann A. , Kana S. K. , Macey L. R. , Bolander M. E. 
Published: February 2005

AbstractThe effect of the administration of acidic fibroblast growth factor (aFGF) on normal fracture healing was examined in a rat fracture model. One microgram of aFGF was injected into the fracture site between the first and the ninth day after fracture either every other day or every day. aFGF‐injected calluses were significantly larger than control calluses, although this does not imply an increased mechanical strength of the callus. Histology showed a marked increase in the size of the cartilaginous soft callus. Total DNA and collagen content in the cartilaginous portion of the aFGF‐injected calluses were greater than those of controls, although the collagen content/DNA content ratio was not different between the aFGF‐injected and control calluses. Fracture calluses injected with aFGF remained larger than controls until 4 weeks after fracture. The enlarged cartilaginous portion of the aFGF‐injected calluses seen at 10 days after fracture was replaced by trabecular bone at 3 and 4 weeks. Northern blot analysis of total cellular RNA extracted separately from the cartilaginous soft callus and the bony hard callus showed decreased expression of type II procollagen and proteoglycan core protein mRNA in the aFGF‐injected calluses when compared with controls. A slight decrease in types I and III procollagen mRNA expression was also observed. We concluded that aFGF injections induced cartilage enlargement and decreased mRNA expression for type II procollagen and proteoglycan core protein.
The three‐dimensional tracking pattern of the human patella
Authors: van Kampen A. , Huiskes R. 
Published: February 2005

AbstractA study was undertaken to provide data on the three‐dimensional tracking pattern of the patella, relative to the femur, in human knee‐joint specimens. For this purpose, a highly accurate roentgen stereophotogrammetric analysis (RSA) method was applied. The three‐dimensional motion patterns of the tibia and the patella were measured and represented in terms of three translations and three rotations each, during knee flexion in neutral (unloaded), endorotated, and exorotated pathways. We found that the patella displays complex but consistent three‐dimensional motion patterns during flexion, which include flexion rotation, medial rotation, wavering tilt, and a lateral shift relative to the femur. The motion patterns are very much affected by tibial rotations accompanying flexion.
Measuring the volume fraction of bone ingrowth: A comparison of three techniques
Authors: Sumner Dale R. , Bryan James M. , Urban Robert M. , Kuszak Jerome R. 
Published: February 2005

AbstractThe need for quick, accurate, and reproducible methods to measure the amount of bone within porous metals has increased as the use of these materials has become more common within orthopedics. The purpose of this paper is to compare measrements of bone ingrowth using microradiography, stained histology, and backscattered electron imaging–scanning electron microscopy (BEI–SEM) in cementless, porous‐coated acetabular components retrived from human patients. BEI–SEM of bone ingrowth into porous metal provided excellent images for quantitative analysis. The stained sections and BEI–SEM images provided very comparable results, while microradiography consistently understimated the porosity of the porous coating and overestimated the amount of bone ingrowth.
Effect of fracture fixation on cortical bone blood flow
Authors: Smith Stephen R. , Bronk James T. , Kelly Patrick J. 
Published: February 2005

AbstractBecause internal and external fixation devices alter blood flow, and thus the transport of nutrients to the cortical bone of a healing fracture, we studied the effects of a fluted intrameduilary rod (IMR), a half‐frame external fixator (EF), and a compression plate (PL) on the cortical bone directly adjacent to the fracture site at 4 and 48 h and 14 and 90 days after fixation. Three specific areas of cortical bone were studied: endosteal cortex, periosteal cortex, and subplate cortex (cortical bone under the compression plate). The fractures fixed with IMR had the lowest blood flow at all time periods studied. At 4 h, the difference between IMR and PL or EF was statistically significant in the endosteal cortex (p < 0.01 or p < 0.05, respectively); also, the difference between the IMR and EF in the subplate cortical bone region was significant (p < 0.05). At 14 days, the blood flow to the endosteal cortex was still significantly lower with IMR than with EF (p < 0.025). At 90 days, the blood flow to the subplate region of cortical bone was significantly (p < 0.02) higher with PL than with IMR but there was no significant difference in bone remodeling with the different fixation devices.
An electron microscopic study of local anesthetic‐induced skeletal muscle fiber degeneration and regeneration in the monkey
Authors: Komorowski Thomas E. , Shepard Beverly , Økland Steinar , Carlson Bruce M. 
Published: February 2005

AbstractAn electron microscopic study was done on abductor pollicis brevis muscles of 18 Rhesus monkeys after intramuscular injections of 0.75% bupivacaine, 2% mepivacaine, or 2% lidocaine + epinephrine. The muscles were examined for from 2 h to 28 days. Severe muscle fiber damage, consisting of breakdown of sarcolemma and myofibrils, was seen as early as 2 h. Phagocyte‐mediated fragmentation of the degenerating muscle fibers was at its peak during the third and fourth days. Myoblasts were abundant during the fourth day. Early myotubes appeared on the fifth and sixth days, and they matured during the second week. Satellite cells appeared alongside mature myotubes. Overall, the local anesthetic‐induced breakdown and regeneration of skeletal muscle fibers in the monkey followed a course quite similar to that seen in the rat.
Differential effects of androgens on cortical bone histomorphometry in gonadectomized male and female rats
Authors: Turner Russell T. , Wakley Glenn K. , Hannon Kathleen S. 
Published: February 2005

AbstractThe physiological role of gonadal androgens in regulating bone metabolism is not established. To determine if androgens antagonize the changes in cortical bone after gonadectomy, we treated orchiectomized (ORX) rats with testosterone (T) and 5α‐dihydrotestosterone (DHT), and ovariectomized (OVX) rats with the afore‐mentioned androgens, as well as the synthetic androgen fluoxymesterone (FI) and the nonsteroidal estrogen diethylstilbestrol (DES). OVX resulted in a rapid, sustained increase in periosteal bone formation at the tibial diaphysis, whereas ORX resulted in decreased bone formation. Androgen treatment stimulated bone formation in ORX rats and suppressed bone formation in OVX rats. A large dose of DES suppressed bone formation in OVX rats to values below the intact controls. The results of these studies demonstrate that androgens counteract the changes in cortical bone formation after gonadectomy in females as well as males, and thereby reestablish the sex difference observed in intact rats.
Measurement of blood flow to the tibial diaphysis using 11‐μm radioactive microspheres. A comparative study in the adult rabbit
Authors: Triffitt Paul D. , Gregg Paul J. 
Published: February 2005

AbstractThe commonly used size of microsphere for bone blood flow estimation is 15 μm, because it has appeard to be the smallest size that is not subject to significant nonentrapment in bone. Soft‐tissue studies suggest that it is microspheres of 9‐10 μm or less that pass through peripheral tissues and give low calculated flows, whereas many vessels passing into and within cortical bone are < 15 μm in diameter. We have therefore performed a comparison between microspheres approximately 15 and 11 μm in average size. Blood flows to the cortex and marrow of the tibial diaphysis, and to the skeletal muscle of the anterior compartment, were obtained in six adult New Zealand White rabbits by the reference sample technique, injecting microspheres of 16.5+ 0.1 μm and 11.3+ 0.1 μm simultaneously. The calculated cortical flows averaged 2.07 and 2.51 ml/min/100 g, respectively, and the marrow flows 26.63 and 24.92 ml/min/100 g. Mean skeletal muscle flows were 15.57 and 14.54 ml/min/100 g, respectively. There were no significant differences between the calculated flows for the two sizes of microsphere. Thus, the smaller microspheres do not appear by this method to be subject to significant nonentrapment, and they are therefore suitable for blood flow measurement in these tissues.
The influence of support conditions in the loading fixture on failure mechanisms in the push‐out test: A finite element study
Authors: Harrigan T. P. , Kareh J. , Harris W. H. 
Published: February 2005

AbstractThe usefulness of the push‐out test as an indicator of interface strength was evaluated using finite element models of intact and partially failed cylindrical push‐out specimens loaded against a rigid annular support. The irregular stress distributions that were found in intact specimens depended more on interface conditions at the loading fixture than on a 35% increase in interface area. The maximum stress at the interface was a tensile stress. Critical energy release rates for interface failure were calculated for flawed specimens in which flaw size was either 10 or 100 μm, and for boundary conditions at the loading fixture that were either fixed or slipping in the radial direction. The critical energy release rates depended heavily on the support boundary conditions. Thus, the results of parametric push‐out tests can be reasonably compared only for specimens that are very similar in geometry and that are loaded in very carefully controlled fixtures.