bluuebunny/crossref_metadata_2025_split huggingface dataset:
Less rigid internal fixation plates: Historical perspectives and new concepts
Authors: Woo S. L‐Y. , Lothringer K. S. , Akeson W. H. , Coutts R. D. , Woo Y. K. , Simon B. R. , Gomez M. A. 
Published: February 2005

AbstractIn the application of “rigid” plates for diaphyseal fractures, lack of callus healing and overprotection of the underlying bone are viewed by many investigators as undesirable consequences. Potential solutions offered to overcome these deficiencies include modification of the timing of plate removal, use of biologically degradable materials for plates so that stressshielding can be minimized, and use of less rigid plate fixation systems. This study emphasizes the selection of appropriate design criteria for less rigid plate‐fixation systems. To accomplish this goal, the axial, bending, and torsional stiffness parameters are considered in place of the oversimplified terms such as “flexible plate” or “elastic fixation.” With the aid of finite element modeling and simplified bench experiments, we performed parametric studies and singled out the plate axial stiffness as the dominant factor in altering the bone stresses. As a result, we designed two experimental plates, one a thin Ti‐6Al‐4V (titanium with 6% aluminum and 4% vanadium) alloy plate with low stiffness in axial and bending directions, and the other a tubular stainless steel plate with low stiffness in the axial direction but moderate stiffness in bending and torsional directions. The low‐stiffness Ti‐6Al‐4V alloy plate was first tested in a demanding bilateral canine midshalt osteotomy, and proved to be inadequate. Both experimental plates were successful in the unilateral osteotomies, with the tubular plate yielding the best results. After 6 months of plating, the bones beneath the tubular plate had superior mechanical and structural properties as compared to those of the control “rigid” stainless steel and the Ti‐6Al‐4V alloy plates. Application of this plate prolonged for 9 months did not cause reduction in bone properties and strength. The success of the tubular plate is due to its moderate bending and torsional stiffnesses, which provide adequate fixation to achieve callus union, while its low axial stiffness permits the underlying bone to share the physiological stresses needed for bone remodeling. These drastic changes in mechanical demands on the internal fixation plate during the early healing phase and the postunion remodeling phase are discussed.
Age‐related changes in bone in the dog: Fluid spaces and their potassium content
Authors: Pinto Manuel R. , Kelly Patrick J. 
Published: February 2005

AbstractWe measured erythrocyte, plasma, osteocyte, extravascular extracellular, and total water fluid spaces and calculated their K content in cortical bone of dogs of various age. Total and exchangeable K were measured by atomic absorption spectroscopy and by volume of distribution techniques, respectively. All fluid spaces in bone decreased with increasing age of the dogs. The total and exchangeable K contents of cortical bone and the K content calculated from the fluid spaces were within the same range in each age group. These values all fell with increasing age.
Fatigue crack propagation behavior of ultrahigh molecular weight polyethylene
Authors: Connelly G. M. , Rimnac C. M. , Wright T. M. , Hertzberg R. W. , Manson J. A. 
Published: February 2005

AbstractThe relative fatigue crack propagation resistance of plain and carbon fiber‐reinforced ultrahigh molecular weight polyethylene (UHMWPE) was determined from cyclic loading tests performed on compact tension specimens machined from the tibial components of total knee prostheses. Both materials were characterized by dynamic mechanical spectroscopy, X‐ray diffraction, and differential scanning calorimetry. The cyclic tests used loading in laboratory air at 5 Hz using a sinusoidal wave form. Dynamic mechanical spectroscopy showed that the reinforced UHMWPE had a higher elastic storage modulus than the plain UHMWPE, whereas X‐ray diffraction and differential scanning calorimetry showed that the percent crystallinity and degree of order in the crystalline regions were similar for the two materials. Fatigue crack propagation in both materials proved to be very sensitive to small changes in the applied cyclic stress intensity range. A 10% increase in stress intensity resulted in approximately an order of magnitude increase in fatigue crack growth rate. The fatigue crack propagation resistance of the reinforced UHMWPE was found to be significantly worse than that of the plain UHMWPE. This result was attributed to poor bonding between the carbon fibers and the UHMWPE matrix and the ductile nature of the matrix itself.
Demonstration of increased proteoglycan turnover in cartilage explants from dogs with experimental osteoarthritis
Authors: Carney Stephen L. , Billingham Michael E. J. , Muir Helen , Sandy John D. 
Published: February 2005

AbstractThe turnover of proteoglycans (assessed by the release into the medium of newly synthesised [35S]‐proteoglycan) in explant cultures of articular cartilage from various anatomical sites of the knee joints (stifle) of mature beagles with experimental osteoarthritis has been studied with the following findings: (a) The proportion of newly synthesised proteoglycans released from cartilage explants maintained in vitro was generally increased for cartilage from operated compared with nonoperated control joints. (b) At 3 weeks after surgery there was a significant increase in the release of [35S]‐proteoglycans from explants of the lateral and medial tibial plateaux of operated joints compared with sham‐operated joints but not from other sites. On the other hand, when this comparison was made at 3 to 6 months after surgery, significant increases in the release of [35S]‐proteoglycans were observed from cartilage of all anatomical areas except the patellar groove. (c) The release of [35S]‐proteoglycan from cartilage explant cultures was dependent on live chondrocytes, since freeze‐thawing the tissue immediately after labelling markedly reduced the release from both normal and osteoarthritic cartilage.
Bone density in women: College athletes and older athletic women
Authors: Jacobson P. C. , Beaver W. , Grubb S. A. , Taft T. N. , Talmage R. V. 
Published: February 2005

AbstractBone density was studied in intercollegiate athletes and older athletic women. Single‐photon densitometry was used to assess bone density parameters at a new distal radial site, the midradius, and the first metatarsus. Dual‐photon densitometry assessed bone density of the lumbar spine. Eleven intercollegiate tennis players, 23 swimmers, and 86 older “athletic” women from 23 to 75 years of age were compared with age‐matched nonathletic controls. “Athletic” describes adult women who exercised at least three times per week, 8 or more months of the year, for a minimum of 3 years. The radius and metatarsus bone content of intercollegiate athletes was significantly above control values. Lumbar spine density was significantly higher only in tennis players. Mean bone density values for adult “athletic” women were also significantly greater than in age‐matched controls. In the oldest athletic group (55–75 years of age) bone measurement values in radius and lumbar spine were in the same range as for younger “athletic” women. In contrast, after 50 years of age, these values in the control population decreased by 0.7%/year. Therefore the largest variance (increase) from age‐matched controls occurred in the oldest “athletic” group. Also, we have established a distal radial density value (using our modified site) below which we consider women “at risk” and recommend further bone health evaluation. Only two adult athletic women > 55 years of age fell into this category. It is concluded from this cross‐sectional study that a regularly maintained athletic program for adult women may reduce the rate of “normal” bone mass loss accompanying age, particularly postmenopausally. Whether this will also decrease the risk of nontraumatic fractures in later life has yet to be determined.
Intervertebral disc degeneration in adult mice with hereditary kyphoscoliosis
Authors: Mason R. M. , Palfrey A. J. 
Published: February 2005

AbstractBreeding experiments confirmed that a hereditary form of kyphoscoliosis in the BDL strain mouse was due to an autosomal recessive gene (ky). Sagittal sections of whole vertebral columns from adult homozygous recessive mice (ky/ky) were examined histologically. All mice showed varying degrees of degenerative change in one or more intervertebral discs between the fifth cervical and the second thoracic vertebrae. The changes comprised loss of cells, loss of distinction between nucleus pulposus and annulus fibrosus, loss of characteristic ring‐like structure in the annulus, and development of wedge‐shaped discs. In most animals, degenerative disc substance protruded from the disc space, usually posteriorly, sometimes anteriorly, and occasionally through the vertebral end plate cartilage. Posterior protrusions impinged on the spinal cord.
Abnormality of cartilage collagen in a patient with unclassified chondrodystrophy
Authors: Sussman Michael D. , Kelly Thaddeus , Rosenbaum Kenneth N. , Balian Gary 
Published: February 2005

AbstractWe have described a previously unrecognized chondrodystrophy characterized by short‐limbed dwarfism, blue sclera, severe cardiopulmonary problems, and failure of postnatal growth. The first of two siblings thus affected died at age 6 months following attempted correction of an atrial septal defect. Growth plate cartilage from multiple sites obtained at autopsy showed a marked abnormality of architecture on the light microscopic level. Biochemical studies demonstrated an absence of normal α 1(II) collagen in costochondral junction growth plate cartilage and an appearance of the major collagen in a band which comigrates on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis with 3α collagen. Cartilage extracted from structural rib appeared to be normal.
Effects of low‐modulus coatings on pin–bone contact stresses in external fixation
Authors: Manley M. T. , Hurst L. , Hindes R. , Dee R. , Chiang F. P. 
Published: February 2005

AbstractThe intent of this study was to investigate the stress distribution in cortical bone around fracture fixation pins and around pins coated with various polymeric and elastomeric materials. Since these interface stresses cannot be measured directly, a photoelastic technique was employed and stresses were measured in two‐dimensional bone models fabricated from sheets of epoxy resin. Our results showed that when a fixation pin was loaded in compression, the compressive stress measured in the model was greatest at the pin–model interface. The magnitude of the compressive stress was found to diminish steeply away from the hole in a log decrement distribution which was asymptotic to the value of the average stress in the model. When polymeric and elastomeric materials were applied as pin coatings and the performance of the coated pins was compared to that of uncoated pins of the same overall diameter, a reduction of the maximum stress in the bone model was demonstrated. Among the coatings tested, we found that of the polymeric materials ultrahigh molecular weight polyethylene (UHMWPE) was most effective at reducing the peak cortical stress magnitude. The most effective coating material overall was found to be silicon elastomer. Computation of stress values in models loaded through stainless‐steel pins and through pins coated with 1‐mm silicon elastomer showed that the presence of the elastomer layer caused a reduction of about 50% in the maximum compressive stress in the model.
In vivo strain patterns in the four major canine knee ligaments
Authors: Monahan John J. , Grigg Peter , Pappas Arthur M. , Leclair Walter J. , Marks Thomas , Fowler David P. , Sullivan Thomas J. 
Published: February 2005

AbstractUsing mercury gauges, we measured strains in vivo in the four major ligaments of the canine knee joint as the tibia was loaded in valgus or varus at fixed angles of knee flexion. Free axial rotation of the tibia on the femur was allowed. Forces up to 78.4 N were applied to the tibia, producing moments of approximately 9 N‐m. We found that with valgus loading, significant strains were observed in the medial collateral ligament at extension. At 45° of flexion, the medial collateral, posterior cruciate, and anterior cruciate were strained. At 90° of flexion, all four ligaments were strained. With varus loading, significant strains were found in the lateral collateral and anterior cruciate at extension. The lateral collateral and anterior cruciate ligaments were strained at 45° of flexion. At 90° of flexion, the lateral collateral, anterior cruciate, and posterior cruciate ligaments were strained. With valgus loading, the tibia rotated internally and the degree of axial rotation increased with flexion. External rotation of the tibia resulted from varus loading, and was relatively constant through the range of flexion. Thus when axial rotation is allowed, stability of the knee in response to valgus and varus loads is maintained by the cruciates as well as the collaterals, and the role of the cruciates increases with flexion and axial rotation.
Characterization of arthroplasty tissue after 14 years post‐cup arthroplasty: A morphological and biochemical assessment
Authors: Coutts Richard D. , Amiel David , Harwood Frederick L. , Bradley Gary , Akeson Wayne H. 
Published: February 2005

AbstractThe cup arthroplasty has been reported to cause the formation of a fibrocartilaginous joint surface, which may result in a painless, functional joint. The joint surface of a 38‐year‐old man with a failed cup arthroplasty implanted for 14 years was examined histologically and biochemically. The joint surface tissue of this patient resembled fibrous connective tissue, with major types of collagen being Type I and Type III. No evidence of cartilaginous transformation in the healing scar was demonstrated, despite several years of successful functioning of the cup arthroplasty.
The organization of collagen in cryofractured rabbit articular cartilage: A scanning electron microscopic study
Authors: Clark John M. 
Published: February 2005

AbstractAdult rabbit articular cartilage was prepared for scanning electron microscopy using, in order, glutaraldehyde fixation, enzymatic removal of proteoglycan, dehydration in ethanol, cryofracture in liquid nitrogen, and criticalpoint drying. Enzymes were effective in fixed material. Fixation, cryofracture, alignment of fracture surfaces with “split lines,” and retention of subchondral bone were found to be necessary steps for the preservation of collagen detail. The fibrous framework was found to be similar to that proposed by Benninghoff and favored by more recent phase‐contrast microscopic studies. Vertical fibers extending from subchondral bone and a network of tangentially oriented superficial fibrils converge in the transitional zone. No random layer is seen. Pericellular capsules interdigitate with the vertical fibers. When cartilage is prepared in a manner that minimizes tissue damage, scanning electron microscopy provides useful, unique information.
Induction of heat‐shock protein synthesis in chondrocytes at physiological temperatures
Authors: Madreperla Steven A. , Louwerenburg Binno , Mann Robert W. , Towle Christine A. , Mankin Henry J. , Treadwell Benjamin V. 
Published: February 2005

AbstractInduction of heat‐shock protein (HSP) synthesis is demonstrated in cultured calf‐chondrocytes at temperatures shown to occur in normal human cartilage during experiments subjecting intact cadaverous hip joints to the parameters of level walking. A 70,000 MW heat‐shock protein (HSP‐70) is synthesized by chondrocytes at temperatures above 39°C, while induction of synthesis of a 110,000 MW HSP only occurs at temperatures of 45°C or greater. These differences in critical temperatures for induction, and data showing differences in kinetics of induction and repression of synthesis, suggest that there are differences in the mechanism of induction of the two HSPs. The duration of HSP synthesis and inhibition of synthesis of normal cellular proteins is directly proportional to the duration and magnitude of the temperature rise. Possible relationships between these new findings and the initiation and progression of degenerative joint disease are discussed.
Bone ingrowth into three different porous ceramics implanted into the tibia of rats and rabbits
Authors: Uchida Atsumasa , Nade Sydney , McCartney Eric , Ching William 
Published: February 2005

AbstractThree different porous ceramics—calcium aluminate, calcium hydroxyapatite, and tricalcium phosphate—were implanted into the proximal tibia in rats and rabbits to study the interactions between these ceramics and a bony site that is abundant in bone marrow. New bone was consistently formed within the bone marrow surrounding and adjacent to all three types of ceramics. Calcium hydroxyapatite and tricalcium phosphate ceramics permitted bone ingrowth into their pores. The newly formed bone was found only in the part of the ceramic intruding into the bone, not in the portion protruding in the soft tissues outside the tibia. Partial replacement of the new bone opposite the medullary portion by new hemopoietic marrow occurred with longer implantation times. In contrast, no bone was seen within the pores of any of the calcium aluminate implants.
A cumulative damage model for bone fracture
Authors: Carter D. R. , Caler W. E. 
Published: February 2005

AbstractA mathematical model is presented to describe the combined time‐dependent and cycle‐dependent fracture characteristics of devitalized cortical bone. Failure is interpreted based on a linear‐life fraction rule, which accounts for cumulative creep and fatigue damage under arbitrary loading histories. The model is successful in describing the influence of loading rate on monotonic tensile strength, the time to failure in constant stress creep‐fracture tests, and bone fracture in zero‐tension and tension‐compression cyclic loading. The possible implications of the model to in vivo bone fracture, deformity, and remodelling in response to various loading histories are considered.
Effects of short‐term Cyclosporin‐A on biomechanical properties of intact and fractured bone in the rat
Authors: Warren Steven B. , Pelker Richard R. , Friedlaender Gary E. 
Published: February 2005

AbstractCyclosporin‐A is a new immunosuppressant drug being used widely for solid organ transplantation. The systemic effects of Cyclosporin‐A on the skeletal system have not previously been defined. This study examined the effects of Cyclosporin‐A on biomechanical properties of intact bone and fracture repair in a rat model. Closed midshaft femoral fractures were produced over a preplaced intramedullary pin. Cyclosporin‐A, dissolved in olive oil and administered by gavage, was begun the day following surgery and continued for 14 consecutive days at a dose known to prolong solid organ allograft survival in rats (7 mg/kg/day), and a second group of control animals received comparable volumes of plain olive oil under identical circumstances. Groups of both experimental and control animals were killed at 4, 8, 12, or 16 weeks following fracture, after which both intact and fractured femurs were tested to failure in torsion. As judged by torque, angular deformation, stiffness, and energy absorption, Cyclosporin‐A did not significantly alter the biomechanical properties of fracture repair or intact bone turnover. Based on current biomechanical data, we can find no reason to discourage the short‐term clinical use of Cyclosporin‐A in patients with or without fractures. Histomorphometric studies are required to accurately assess the biologic effects of this drug on bone biology and to complete the analysis of skeletal toxicity.
Temporal course of bone formation in response to constant direct current stimulation
Authors: Esterhai J. L. , Friedenberg Z. B. , Brighton C. T. , Black J. 
Published: February 2005

AbstractReactive, post‐traumatic bone formation in response to intramedullary insertion of a polytetrafluorethylene‐coated, 28 gauge stainless steel wire was compared with the sequential bone formation seen in response to an indentical intramedullary stainless steel cathode delivering 20 μA constant direct current. Animals were studied at days 1, 2, 3, 4, 5, 7, 9, 11, 14, 17, and 21 after wire insertion. Point count analysis revealed progressive bone formation beginning as early as day 3 on the constant direct current‐stimulated side, progressing steadily through day 21. Control tibia, however, began to show bone formation on day 5 with peaking at day 9 and subsequent bone resorption. The osteogenic response at the 20 μA cathode was statistically elevated above that seen at the control on days 11, 17, and 21.
Matrix vesicle enzymes in human osteoarthritis
Authors: Einhorn Thomas A. , Gordon Stanley L. , Siegel Scott A. , Hummel Charles F. , Avitable Matthew J. , Carty Robert P. 
Published: February 2005

AbstractThe enzymatic activities and in vitro calcification properties of matrix vesicle fractions isolated from normal and osteoarthritic (OA) human articular cartilage were compared to determine the essential conditions for calcification in these tissues. Four groups of human cartilage were examined, I, normal articular cartilage from aged, nonOA joints; II, discolored or fibrillated cartilage from OA joints; III, osteophytic cartilage from OA joints; IV, loose body cartilage from OA joints. Fetal bovine growth plate cartilage was also studied. Both ATP‐ and 5′‐AMP‐dependent in vitro matrix vesicle calcification occurs in all cartilage groups examined and, for human articular cartilage, these activities increase progressively from Groups I to II to III. Calcification does not occur in the absence of either phosphate or pyrophosphate. Alkaline phosphatase, 5′‐AMPase, and ATP:pyrophosphohydrolase activities are increased in Groups III and IV cartilage compared with Group I and are detected at high levels in fetal bovine growth plate cartilage. Pyrophosphatase activity occurs in only those cartilage groups juxtaposed to areas of new bone formation (osteophytic, loose body, and bovine growth plate). These results suggest that OA, growth plate, and even normal articular cartilage all have the potential to undergo calcification as long as both phosphate and pyrophosphate ions can be generated at sufficiently high levels. However, the capacity for cartilage to deposit hydroxyapatite, as it does during bone formation, may depend on the presence of pyrophosphatase activity.
Antibiotic absorption from infected and normal joints using a rabbit knee joint model
Authors: Schurman David J. , Kajiyama Glen 
Published: February 2005

AbstractAn understanding of the absorption of antibiotics from joints was investigated comparing intraarticular (i.a.) absorption with intramuscular (i.m.) absorption in rabbit knee mode. The antibiotics investigated were methicillin, cephalothin, cefazolin, cefoxitin, amikacin, neomycin, kanamycin, and gentamicin. Absorption was measured both in animals in which the knee joint was infected with Staphylococcus aureus and in normal animals. The pattern of absorption from infected joints 37% slower than from an i.m. injection. In animals that are not infected i.a. antibiotics are actually absorbed 12% faster than i.m. anitbiotics. Thus, i.a. antibiotics are absorbed rapidly and similarly to i.m. injection and should be included in total dose calculations for antibiotic regimens, especially with regard to their potential toxicity.