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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 1 (1983), S. 1-3 
    ISSN: 0736-0266
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0736-0266
    Keywords: Cartilage degeneration ; Meniscectomy ; Indentation ; Glycosaminoglycans ; Osteoarthrosis ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have correlated early material and biochemical changes in articular cartilage in a surgical model for cartilage degeneration. Medial meniscectomy was performed on the left knee of 17 adult, female New Zealand white rabbits. The equilibrium Young's modulus of cartilage was assessed by an indentation test in situ at defined sites on the medial and lateral tibial plateaus of the operated and control knees; the cartilage was then excised and analyzed biochemically. Focal changes were consistently observed in the medial surface of the operated knee. The equilibrium modulus and the glycosaminoglycan content fell rapidly, reaching a minimum by 2 weeks after surgery; the lateral tibial surface was essentially unaffected. Six months after surgery, the glycosaminoglycan content had returned to normal and the modulus to near normal. Independent measurements on cored plugs from the medial surface 2 weeks after surgery revealed a significant decrease in both the dynamic stiffness and the streaming potential in the operated knee compared with the control. The findings suggest that normal ambulatory loads in vivo will deform the affected medial cartilage much more than normal. It remains to be seen if altered mechanical stresses are solely responsible for initiating and sustaining matrix remodeling by the chondrocytes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0736-0266
    Keywords: Synovium ; Cartilage ; Breakdown ; Synthesis ; Catabolin ; Hydrocortisone ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cartilage-synovium interactions were explored in a model culture system. Bovine nasal-cartilage discs were cocultured with minced rheumatoid synovium or synovium-conditioned media (SCM) in the presence or absence of hydrocortisone. Cartilage breakdown was assessed by the release of proteoglycan (PG) and hydroxyproline, and matrix biosynthesis by [35S]sulfate incorporation during pulse labeling. Chondrocyte-dependent breakdown in response to synovial factors (i.e., “catabolin” activity) was assessed by the difference in PG release between living and dead cartilages. Short-term contact with minced synovial membrane or exposure to its products released at a distance was sufficient to induce cartilage degradation in coculture; continued exposure was not required for breakdown to persist. Conditioned media from short-term synovial culture were similarly potent, and the induced breakdown was chondrocyte dependent. Matrix biosynthesis was inhibited in exposed cartilage but could be rapidly restored to normal on synovium removal despite the persistence of cartilage breakdown. Early hydrocortisone treatment suppressed the initiation of cartilage breakdown in cocultures and largely abolished the appearance of inductive factors in SCM. Later applications had little effect either in cocultures or in catabolin assays. We conclude that synovium-induced breakdown is an early event and that chondrocyte catabolic mechanisms once they have been activated are sufficient to maintain breakdown at a high level. Hydrocortisone, as well as limiting proteolysis, inhibits early tissue interactions at the level of synovial catabolin production or release.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0736-0266
    Keywords: Mechanical properties ; Medial collateral ligament substance ; Strain ; Strain distribution ; Strain variations ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This investigation presents a new approach in the measurement of the mechanical properties of the ligament substance from tensile testing of a bone-ligament-bone complex. Such basic information should be one of the necessary prerequisites in the evaluation of ligament repair as well as reconstruction by autogenous tissue grafts or artificial ligament implants. The use of a video system permits the determination of tensile strains of the mid-medial collateral ligaments from the canine, swine, and rabbit without mechanically interfering with the ligament deformation during testing. This methodology further eliminates the difficulties of measuring the initial length of the entire medial collateral ligament, as its insertions to bones are ambiguous and cover a large area. It was found that the strain of the ligament substance is consistently and considerably less than specific deformation of the bone-ligament-bone complex. These data suggest that the ligament-bone structure stretches nonuniformly with the highest deformation occurring near or at the ligament insertion sites to bone. Other interesting findings include the variation of tensile strains along the ligament substance for all animal species studied.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 1 (1983), S. 30-41 
    ISSN: 0736-0266
    Keywords: Stress-generated potentials ; Streaming potentials ; Piezoelectricity ; Electromechanical effect ; Strain-related potentials ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The objective of this study was to determine the origin of stressgenerated potentials (SGPs) in fluid-saturated bone. Stress-generated potentials were studied as a function of the conductivity, NaCl concentration, and viscosity of the fluid contained within cortical human and bovine bone. Bone samples were soaked in solutions in which NaCl and sucrose concentrations were systematically varied. Macroscopic SGPs and their relaxation times were measured as a function of these properties. Stress-generated potentials were also measured as a function of conductivity and NaCl concentration by using a microelectrode. The results of this study confirmed that the properties of the fluid in bone have a great influence on the magnitude and time dependence of the SGP. Especially notable was the observation that solutions of high NaCl concentration consistently reversed the polarity of the SGP. These results are consistent with streaming potential theory. Although fluid-saturated bone may retain some piezoelectric properties, SGPs are predominantly caused by streaming potentials.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0736-0266
    Keywords: Joint flexibilities ; Idiopathic scoliosis ; Spine biomechanics ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Seven clinical measurements of joint flexibilities were made in 51 girls with untreated mild idiopathic scoliosis and 65 girls with structurally normal spines. Subject ages ranged from 10 to 16 years. Abilities to have the index finger passively extended, the wrist bent, and the elbow and the knee hyperextended, along with abilities to bend the trunk voluntarily forward and to the right and left sides, were measured. The girls with scoliosis in the mean either had the same flexibilities or were less flexible than the normal girls. The study provided no evidence that untreated mild idiopathic scoliosis occurs or progresses because of increased joint flexibilities.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0736-0266
    Keywords: Bone resorption ; Immobilization ; Bone mass ; 45Calcium ; [3H]Tetracycline ; [3H]Collagen ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The major effect of immobilization during growth is a smaller bone mass induced by either an increased bone resorption or a decreased bone formation. Using a method of analyzing radioisotopic loss of [3H]tetracycline and [3H]collagen from bone prelabeled in vivo, we compared the amount of bone resorption due to immobilization with bone resorption induced by growth. One hind limb was denervated in growing male rats, 6 weeks of age, that had been chronically prelabeled with [3H]tetracycline, 45calcium, and [3H]proline. The total radioactivity of the whole femur and tibia/fibula from the denervated limb was compared with that from bones of the control limb at 0, 1, 2, 4, and 8 weeks after denervation. The effect of growth on bone formation was measured by net increases in bone length, volume, and mass of matrix and mineral. Experimental bones had a significantly smaller volume and mass. Bone resorption was much greater during growth modeling than during denervation. The additional bone resorption induced by denervation was a small fraction (one-fourth) of the resorption induced by growth. Denervation during growth resulted in less bone being formed due to a smaller gain in matrix and mineral mass as a result of a reduction in bone formation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0736-0266
    Keywords: Normal gait ; Mechanical work ; Metabolic energy consumption ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The validity of using mechanical measures of work to indicate the metabolic energy consumption during normal gait was examined. These mechanical measures were (a) mechanical work done on the center of mass per kilogram body mass per second (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot W_{{\rm cm}} $\end{document}), calculated by integration of ground reaction forces measured by force platforms; (b) total body segmental work per kilogram body mass per second (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot W_{{\rm seg}} $\end{document}), calculated from individual body segment energies measured by motion analysis; and (c) the sum of the normalized absolute moment impulses per second acting on the joints of the lower extremities (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot M $\end{document}), calculated from both force and motion data. The metabolic energy consumption, determined by analysis of expired air, and the three mechanical measures of work were calculated for six normal subjects walking at five speeds. Each measure of mechanical work per second walked was highly correlated with metabolic energy consumption/kg · s (r = 0.89 for Wcm, r = 0.79 for \documentclass{article}\pagestyle{empty}\begin{document}$ \dot W_{{\rm seg}} $\end{document}, and r = 0.85 for M), but a poorer correlation was found between each measure of mechanical work per meter walked and net metabolic energy consumption/kg. m (r = 0.54 for Wcm, r = 0.28 for Wseg, and r = 0.03 for M). These mechanical parameters, particularly when measured per time, may be useful in comparing metabolic energy consumption between individuals or between different walking conditions for the same individual.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0736-0266
    Keywords: Rabbit growth plates ; Proximal tibiae ; Oxytetra-cycline labeling ; Electrical stimulation ; Growth acceleration ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The right proximal tibial growth plates of adolescent New Zealand white rabbits were stimulated with various capacitively coupled electrical fields. Capacitor plates attached to plastic jigs placed over the proximal tibiae were connected to function generators which supplied sine wave signals of 60 kHz frequency and various voltages (2.5, 5, 10, and 20 V peak-to-peak). At 0 hand at 48 h, each animal was labeled with intravenously injected oxytetracycline. For the next 48 h, each right proximal tibial growth plate was stimulated with one of the above electrical signals. At the end of the 48 h of stimulation, the animals were sacrificed, and the tibiae were excised; histological sections of the proximal growth plate in each tibia were made, and the distance the labels moved away from the bone-cartilage junction down into the metaphysis was measured under fluorescent microscopy. Results indicate that the rabbit growth plate can be consistently stimulated to statistically significant accelerated growth in a capacitively coupled electrical field. A dose-response effect was noted, with 5 V peak-to-peak exhibiting maximum growth acceleration. Thus, the application of the proper capacitively coupled electrical field significantly stimulated the rabbit growth plate at voltage and current levels that are safe for human use.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0736-0266
    Keywords: Walking ; Energy requirements ; Gait characteristics ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Normative data that summarize the energy requirements and gait characteristics of level outdoor walking were determined in 111 normal subjects between the ages of 20 and 80 years. Subjects were divided into two age groups: young adults (20-59 years) and senior subjects (60-80 years). The mean rate of oxygen consumption for young adults and senior subjects did not significantly differ, averaging 11.9 ml/kg-min for both groups. The data on heart rate paralleled the findings on oxygen consumption, averaging 100 and 103 beats/ min, respectively. The net oxygen cost per meter walked for senior subjects, 0.16 ml/kg-m, was significantly greater (p 〈 0.0005) than the value for young adults, 0.15 ml/kg-m, due to a decline in the average walking speed. The average gait velocity for senior subjects, 73 m/min, was statistically significantly less (p 〈 0.0005) than the values for the younger adults, 80 m/min.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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