bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prevention of ectopic bone formation by local application of ethane‐1‐hydroxy‐1,1‐diphosphonate (EHDP): An experimental study in rabbits
Authors: Ahrengart L. , Lindgren U. 
Published: February 2005

AbstractThis report shows that ectopic bone formation, a serious problem in orthopedic surgery, can be controlled in an animal model by local application of EHDP (disodium‐ethane‐1‐hydroxy‐1,1‐diphosphonate). The results might be particularly pertinent to the clinical problem of preventing the recurrence of ectopic bone after surgical excision. Male New Zealand white rabbits were treated with immobilization and intermittent passive manipulation of the right knee. The treatment caused bone formation in the quadriceps muscle, which was visible on radiographs after 3 weeks. In this model, the effect of methacrylate implants containing EHDP was studied. A concentration of 16 g EHDP/100 g methacrylate inhibited bone formation in experimental cortical defects. Release of radiolabeled EHDP was studied in an in vitro system. The release of the drug was approximately 20 mg/day and implant initially, decreasing to about 0.1 mg/day/implant after 30 days.Standardized implants containing 16 g EHDP/100 g were then surgically attached to the femur, and the ectopic bone formation created by immobilization and intermittent manipulation was compared with that in rabbits treated with implants but without EHDP. The ectopic bone was measured from lateral and frontal radiograms and from radiograms of serial transverse sections of the thigh. We found that the EHDP implants were capable of preventing major ectopic bone formation in all cases, whereas all rabbits with an implant containing no EHDP had substantial ectopic bone formation at the end of the experiment. There was no difference between groups in the relative amount of cartilage, connective tissue, and normal bone. We conclude that local administration of EHDP may be a useful method for prevention of ectopic bone formation under the conditions and time employed.
Computerized tomography of proximal femoral trabecular patterns
Authors: Kerr Roger , Resnick Donald , Sartoris David J. , Kursunoglu Sevil , Pineda Carlos , Haghighi Parviz , Greenway Guerdon , Guerra Jose 
Published: February 2005

AbstractA comprehensive imaging and pathologic investigation utilizing patients and cadaver material was performed in order to identify the normal trabecular pattern of the proximal femur and to assess alterations in this pattern in various disorders. Patients and specimens were studied with computed tomography (CT), including three‐dimensional CT image reconstruction in selected cases and plain film radiography. The CT imaging of the proximal femur provides insight into the dynamic state of bone in this region. Despite limited resolution, three‐dimensional CT image reconstruction is capable of portraying the concentration and orientation of major trabeculae in the proximal femur. Increased trabecular spacing occurs in osteoporosis and is well depicted by CT. Proliferation and thickening of the most superior subchondral primary compressive trabeculae is an early sign of osteoarthritis. In the region of the calcar femorale, crossing trabeculae, similar to the appearance of an enchondroma or bone infarct, have been described in osteoporosis and osteoarthritis and probably represent unmasking of normally present reinforcing trabeculae. In ischemic necrosis, CT should be considered a useful modality for detection of early or mild alterations and may be valuable in treatment planning.
Biomechanical optimization of a model particulate composite for orthopaedic applications
Authors: Gerhart Tobin N. , Hayes Wilson C. , Stern Steven H. 
Published: February 2005

AbstractParticulate composites are a potential solution to the need for an injectable, biocompatible, resorbable material that could be used to reinforce fractures and defects in bone and temporarily to stabilize porous ingrowth prostheses. We have developed a model system for producing and testing particulate composites to determine if mechanical properties suitable for orthopaedic applications can be achieved. The experiments used bovine cortical bone and various forms of hydroxyapatite for the particulate phase and a collagen and particulate reinforced gelatin‐resorcinol‐formaldehyde (G‐R‐F) adhesive for the matrix phase. Using unconfined compression testing, we measured the effects of variation in particulate type, size, shape, and volume fraction on the material properties of the particulate composites. We found that compressive strengths greater than 10 MPa and compressive moduli greater than 100 MPa could be achieved in this model system. Rough and irregular particulates exhibited higher compressive strengths and moduli than smooth and spherical particulates. Mechanical properties were largely independent of particulate size in the range of 125–850 μm diameter. This model system suggests that, with the development of new biocompatible matrix materials, particulate composites with mechanical properties suitable for orthopaedic applications can be achieved.
Flexor tendon repair
Authors: Gelberman Richard H. , Manske Paul R. , Akeson Wayne H. , Woo Savio L‐Y. , Lundborg Goran , Amiel David 
Published: February 2005

AbstractHealing canine flexor tendons treated with either total immobilization, delayed protected mobilization, or early protected mobilization was studied by biomechanical, microangiographic, biochemical, and histologic techniques at intervals through 12 weeks. The healing characteristics of the early mobilization tendons showed higher tensile strengths and improved gliding function than the delayed mobilization and immobilization tendons. Protected passive motion brought about accelerated changes in peritendinous vessel density and configuration, as well as increased repair site total DNA content. While adhesions obliterated the space between the tendon surface and the tendon sheath of the immobilized repairs, the mobilized tendons demonstrated coverage of the repair site by cells from the epitenon by 10 days, and a smooth, gliding surface that was maintained free of adhesions through 42 days. A series of in vitro studies demonstrated the cellular processes involved in the repair: phagocytosis of cellular debris and collagenous fragments by cells from the epitenon, and collagen synthesis primarily by endotenon cells.
Three‐dimensional load‐displacement curves due to froces on the cervical spine
Authors: Panjabi Manohar M. , Summers Donald J. , Pelker Richard R. , Videman Tapio , Friedlaender Gary E. , Southwick Wayne O. 
Published: February 2005

AbstractLoad‐displacement curves were measured for six types of pure force loading of the cervical spine specimens obtained from fresh human cadavers. A new measuring and mounting technique was developed that yielded data for all of the functional spinal units for each specimen tested. All five of the coupled, as well as the main, load‐displacement curves were studied. For anterior and posterior shear loadings, the main resulting motions were translation in that direction (1.6 ± 0.3 and 1.9 ± 0.3 mm), and the major coupled motions were flexion and extension (3.6° ± 1.2° and 6.3° ± 1.2°). The main motions with right and left lateral shear loadings were translations laterally (1.4 ± 0.3 and 1.6 ± 0.3 mm), and the major coupled motions were axial rotations (1.5° ± 0.6° and 2.3° ± 0.6°) and not lateral bending. For compression and distraction loadings, the main motions were translations in that direction (0.7 ± 0.3 and 1.1 ± 0.3 mm), and the major coupled motions were flexion and extension (2.0° ± 1.0° and 2.8° ± 1.0°) and lateral bending (1.4° ± 0.3° and 1.9° ± 0.3°). The neutral zones for anterior and posterior shear forces were 1.6 ± 0.2 mm of translation and 5.8° ± 1.3° of rotation, for lateral shear force 1.4 ± 0.3 mm and 2.0° ± 0.5°, and for compression/distraction 0.6 ± 0.1 mm and 2.8° ± 0.9°.
A longitudinal study of the growth of the New Zealand white rabbit: Cumulative and biweekly incremental growth rates for body length, body weight, femoral length, and tibial length
Authors: Masoud Ibrahim , Shapiro Frederic , Kent Ralph , Moses Alan 
Published: February 2005

AbstractThis longitudinal study documents cumulative and incremental growth in the New Zealand white rabbit from 2 to 34 weeks of age at biweekly intervals. Body weight, body length, femoral length, and tibial length have been assessed in 17 male and 12 female rabbits, with the data tabulated separately. A specially designed restrainer was used that allowed the sequential clinical measurements and femoral and tibial radiographs to be performed without the use of anesthesia. Skeletal growth was complete at 28 weeks, with the 34‐week values thus representing mature adult lengths. The mean body weight at 2 weeks of age was 6% that at 34 weeks, and by 16 weeks, 72% of the weight at 34 weeks was achieved. Weight continued to increase in the adult. The mean body length at 2 weeks was 40% that at 34 weeks, and by 16 weeks, 91% of mature adult length was achieved. The mean femoral length at 2 weeks was 38% of the adult length, and at 16 weeks, it reached 95% of adult length. The mean tibial length at 2 weeks was 38% of the adult length, and 94% of the adult value was achieved by 16 weeks. The longitudinal data document the rate and extent of growth of the New Zealand white rabbit, and allow for more accurate timing and quantitation of physical and systemic interventions on the developing skeleton of the commonly investigated New Zealand white rabbit.
Electromyographic studies of the lumbar trunk musculature during the development of axial torques
Authors: Pope M. H. , Andersson G. B. J. , Broman H. , Svensson M. , Zetterberg C. 
Published: February 2005

AbstractThe myoelectric activity of selected trunk muscles at the L3 level was studied during the development of a controlled isometric axial torque. Muscle activity was recorded with surface electrodes bilaterally over the erector spinae muscles, the rectus abdominus, the obliques externus, and the obliques internus. Subjects applied graded isometric axial torque efforts with the addition of a Valsalva. The largest myoelectric activities were recorded over the obliques externus and internus. The side of the muscle developing the torque did show the greatest myoelectric activity, but considerable antagonistic activity was also present. Neither the rectus abdominus nor the internal oblique muscles showed any difference from side to side. The calculated forces in the rectus abdominus and the erectores spinae were high, suggesting that a considerable amount of the muscle contraction was used to control the posture. A Valsalva did not decrease myoelectric activity, but did increase the torque developed.
Immunofluorescent localization of structural collagen types in endochondral fracture repair
Authors: Lane Joseph M. , Suda Marilyn , von der Mark Klaus , Timpl Rupert 
Published: February 2005

AbstractA nonimmobilized rat tibial fracture model of endochondral osseous repair was examined for the unique localizations of specific collagen genetic types. At various stages of the healing process, the demineralized callus was reacted with immunofluorescent antibodies directed against the type specific forms of matrix collagen. Type III collagen rapidly appeared (day 8–10) and remained in the primitive mesenchymal callus until remodeled. It was particularly prominent in the highly vasoformative regions and the pericallus encapsulation but not present in preexisting cortical and neoformed lamellar bone. The type II collagen, a marker of cartilage, was uniquely located only in areas of chondroid differentiation and calcification. Type II collagen was absnet from all bone and was not identified beneath the repairing intact periosteum. The differentiating chondrocytes synthesized type II collagen on an underlayer of type III collagen already within the mesenchymal matrix. From these studies of genetically unique collagen markers, it appears that only in areas of motion or anoxia does an intermediate of chondroid tissue appear. The utilization of specific type II and type III collagen immunofluorescent antibodies has facilitated the understanding of the fracture repair process and has acted as an indicator for unique matrix components.
Effect of hyperbaric oxygen exposure on oxygen tension within the medullary canal in the rabbit tibial osteomyelitis model
Authors: Esterhai John L. , Clark James M. , Morton Harry E. , Smith David W. , Steinbach Andrew , Richter Susan D. 
Published: February 2005

AbstractThe effect on intramedullary oxygen tension of 100% oxygen exposure at 1, 2, 2.4, and 3 atm pressure was studied in 12 New Zealand white rabbits with chronic right tibial osteomyelitis. The model, modified from that described by others, incorporates a multipuncture silastic closure plug placed transcortically in the proximal tibial metaphysis through which platinum needle, polarographic electrode oxygen tension determinations can be made without repeat surgical exposure. In 40% of the control, left, noninfected tibial metaphyses the baseline oxygen tension with the animals breathing room air at sea level was suboptimal for leukocyte bacterial killing. This oxygen tension was depressed further in the infected right tibia. Medullary canal oxygen tension increased in response to hyperbaric oxygen exposure in both the infected and noninfected tibiae. Whereas the amount of the oxygen tension increase varied with the presence of infection and depth of dive, neither the time for oxygen tension to plateau nor the time required for return to baseline tension after completion of hyperbaric oxygen exposure varied with the presence of infection or depth of dive. After completion of hyperbaric oxygen exposure, the oxygen tension within the medullary canal returned to baseline within 15 min.
Effects of mechanical and osmotic pressure on the rate of glycosaminoglycan synthesis in the human adult femoral head cartilage: An in vitro study
Authors: Schneiderman R. , Keret D. , Maroudas A. 
Published: February 2005

AbstractWe studied the effects of mechanical and osmotic compression on sulphate incorporation into glycosaminoglycans of human femoral head cartilage. We found that both mechanical and osmotic compression produce the same lowering of sulphate uptake relative to uncompressed controls. It appears that this effect is not associated with changes in solute transport or changes in solute concentration in the matrix, but is due, in part at least, to an increased osmotic pressure acting on the chondrocytes. A second mechanism of action might be involved directly through the increased proteoglycan concentration in the pericellular environment, resulting from a reduction in the water content. We also found that glycosaminoglycan synthesis returned to its control level when the conditions prevailing in the matrix, in the absence of pressure or added solute, were restored.
Pathogenesis of osteochondrosis juvenilis scheuermann
Authors: Aufdermaur M. , Spycher M. 
Published: February 2005

AbstractIn osteochondrosis juvenilis Scheuermann, foci of various sizes in the cartilaginous end plates of the vertebral bodies display a loosening or complete interruption of the collagen fibers. These findings, together with an alteration and occasional absence of the growth zone, may result in the typical deformation of the vertebral bodies. Electron micrographs of the areas with optically absent collagen fibers reveal collagen fibrils. They are arranged in an irregular pattern. We conclude that a disturbance of collagen or ground substance biosynthesis is of importance in the pathogenesis of juvenile osteochondrosis.
A compliant interface for total knee arthroplasty
Authors: Miegel R. E. , Walker P. S. , Nelson P. C. , Inadomi J. , Needelman L. , Maxine M. 
Published: February 2005

AbstractLow pressure sensitive Fujifilm was used to measure the load distribution between the resected tibial surface and a tibial component at axial loads up to 3,000 N for a rigid interface, a compliant interface of dacron double‐sided velour, and a cemented interface. The pressure patterns consisted of a multitude of small red dots, generally reflecting the slight irregularities of the cut surface and the stiffness of the cancellous bone at the surface. The pressure patterns were photographed with high‐contrast film and input into a computer using a photodiode matrix camera. The data were analyzed to yield the number of contact points for each sample. The velour was more effective in distribution of load to the proximal tibia than the rigid and cemented interfaces, while there was no significant difference between the cemented interface and the rigid interface. A second series of tests showed significant increases in contact points from rigid to one layer to two layers of velour. Cyclic axial loading tests were performed to study the characteristics of rigid and compliant interfaces in a model of in vitro subsidence. Static pressure patterns taken at regular intervals showed that subsidence occurred in vitro in up to ⅓ of the tibias, and that the regions of load transfer could change with time. A model of subsidence was proposed and it was suggested that a velour layer could inhibit the subsidence.
Indium‐111 leukocyte scintigraphic detection of subclinical osteomyelitis complicating delayed and nonunion long bone fractures: A prospective study
Authors: Esterhai John L. , Goll Stephen R. , McCarthy Kevin E. , Velchik Michael , Alavi Abass , Brighton Carl T. , Heppenstall R. Bruce 
Published: February 2005

AbstractTwenty patients were studied prospectively with indium‐labled leukocyte imaging to evaluate its effectiveness in differentiating noninfected delayed or nonunion from osteomyelitis complicating these entities. All patients underwent an open surgical procedure within 24h of the scan. Bone specimens from the nonunion site were obtained for microbiological and histological analysis to confirm the presence or absence of osteomyelitis. In these twenty patients, the sensitivity of the indium scintigraphy was 100%, the specificity 100%, and the overall accuracy 100%. Indium‐labeled leukocyte scintigraphy is significantly more accurate than 99mtechnetium and 67gallium imaging had been, when studied earlier, in detecting subclinical osteomyelitis complicating nonunion. Indium‐labeled leukocyte scintigraphy should supplant sequential technetium and gallium studies in this patient population when the surgeon must determine whether subclinical osteomyelitis is complicating fracture management of delayed and nonunions.
Biochemical characterization of fracture callus proteoglycans
Authors: Kopman C. R. , Boskey A. L. , Lane J. M. , Pita J. C. , Eaton B. 
Published: February 2005

AbstractThe changes in proteoglycan molecules during the initial stages of fracture healing in rats were characterized. Following extraction of callus proteoglycan components with dissociative solvents, the components were purified in a cesium chloride density gradient. The recovered proteoglycans were characterized with respect to their molecular size distribution using gel filtration chromatography and a centrifugal transport methodology. During this early healing period, a decrease was observed in the relative proportion of the aggregate and in the hydrodynamic size and sedimentation coefficients of these molecules. While some molecular degradation could have occurred during the early stages of fracture healing, the dominant change of the proteoglycan molecules seemed to be disaggregation. No significant difference was observed in the proportion of aggregates reformed when exogenous hyaluronate and link glycoproteins. The molecular changes of the proteoglycan molecules seem to parallel those occurring during endochondral calcification of rat epiphyseal cartilage.
Influence of stable fixation on trabecular bone healing: A morphologic assessment in dogs
Authors: Uhthoff Hans K. , Goto Sumio , Cerckel Paul‐Henri 
Published: February 2005

AbstractThe healing patterns of trabecular bone are different from those of compact bone. In order to investigate further this observation, a histomorphometric assessment was undertaken. The influence of internal fixation devices on trabecular bone healing was also studied. Intercondylar osteotomies were produced in 19 dogs and fixed with screws. All dogs were killed between 1 and 14 weeks; eight of them had the screws removed 4 weeks after osteotomy and were killed 4 or 10 weeks later. The results of morphometry were compared to the histologic and radiologic pictures. Anatomic reduction with stable fixation led to contact healing characterized by a narrow endosteal bone formation at the osteotomy site that disappeared only after union was complete (4 weeks). In gap healing, the endosteal bone formation was greater. Internal fixation devices appeared to cause a diffuse osteopenia once union was complete. Their removal just after completion of union seems to prevent the bone loss. Screws induced bone formation around their threads; after they were removed, the reaction disappeared but the screw holes were not filled with normal trabeculate 10 weeks later. Union of fractures through trabecular bone can be assessed radiologically. A decrease of band‐like bone density at the fracture site indicates completion of union. This is the optimal time for implant removal. It prevents the osteopenia observed in cases of continuous presence of screws.
Controlled bending instability in the healing of diaphyseal osteotomies in the rat femur
Authors: Mølster Anders O. , Gjerdet Nils R. , Langeland Norvald , Lekven Jon , Alho Antti 
Published: February 2005

AbstractNinety‐six rats underwent a midshaft transverse osteotomy followed by osteosynthesis with an intramedullary nail, so that the effect of bending instability on time to union and on the mechanical properties of experimental diaphyseal fracture could be evaluted. Rotation was reduced by cementing both nail ends to the bone. Rigid nails made of stainless steel were used on one group and flexible nails made of polyacetal resin were used on another group. Serial radiographs were evaluated at 4‐6‐week intervals. Twelve animals with either nail type were killed at 4, 8, 16, and 24 week. Both femora were mechanically tested and the callus diameters were measured. There was no significant difference in time to union between the two groups. The cross‐sectional area of callus was significantly higher at 8 and 16 weeks in femora with flexible nails. The strength, toughness, and resilience of the bone increased in this group until 24 week. Between 16 and 24 weeks, these parameters did not improve in femora with rigid nails. Poorer mechanical properties in femora with steel nails are interpreted as an effect of stress protection of the bone. This study, therefore, indicates that flexible nails prevent stress protection effects without delaying union.