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  • 1
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In order to describe the impact of corrosion of medical implants on the trace element balance of man samples of blood, serum and of a variety of tissues and organs were analysed for their trace element composition using instrumental neutron activation techniques. By the analysis of blood and serum the trace element status after long-term implantation as well as its dependence on time after implantation was investigated. Using autopsy samples of human organs such as heart, spleen, liver, of aorta and of lymphatic tissue from the lower pelvis transport and storage of the corrosion products was studided. These investigations were supplemented by a comprehensive study of “normal” human blood, serum, tissues and organs from patients without implants. The results demonstrate that there are high enrichments of corrosion products in several tissues and organs and that also blood and serum reveal the presence of the metal implants in the trace element levels, increasing shortly after implantation and pertaining during the entire implantation time. Thus the corrosion of metallic implants is a process not only affecting tissues from the vicinity of the implants but also influencing the trace element balance of the entire organism.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0932
    Keywords: Key words Spinal biomechanics ; Intersegmental muscle forces ; Operative decompression ; Instrumented stabilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Laminectomy is the accepted treatment for spinal canal stenosis in cases where conservative treatment has failed. Opinions diverge on the resulting clinical instability and the necessity of instrumented stabilization. The present biomechanical study was performed to determine the functional impairment following laminectomy and the stabilizing effect of flexible and rigid devices. This was the first time that the effects of agonist and antagonist intersegmental lumbar muscle forces acting on intact, unstable and instrumentally stabilized functional spinal units have been investigated. Six human cadaveric lumbar spines were tested in a spine tester. The coactivation of agonist and antagonist muscle forces resulted in increased stability under the load conditions of bending and rotation; a slight increase in the range of motion was noted during flexion. The functional impairment following laminectomy was corrected by ligamentoplasty and by means of muscle forces. Ligamentoplasty appears to be an alternative to decompression with spondylodesis, especially in patients with well-developed muscles.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-044X
    Keywords: Key words Disko-ligamentous-lesions • Lumbar instability • Dynamic and static stabilisation • Spinal biomechanics ; Schlüsselwörter Diskoligamentäre Läsionen • Lumbale Instabilität • Statische und dynamische Stabilisierung • Biomechanik
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Läsionen des dorsoventralen Ligamentkomplexes führen zu einer Instabilität des lumbalen Bewegungssegments. Prognostisch stellen diskoligamentäre Verletzungen infolge der bleibenden Narbenbildung ein größeres Problem dar als der ossäre Stabilitätsverlust mit rascher Heilungstendenz. Mit der vorliegenden biomechanischen In-vitro-Studie wurden verschiedene Instabilitätsgrade in der Korrelation zum Ausmaß diskoligamentärer Defekte nachgewiesen. Durch eine transpedikuläre Stabilisierung mit einem Schrauben-Ringband-System wurde bei segmentalem Funktionserhalt die Instabilität aufgehoben. Mit einem rigiden Schrauben-Stab-System verblieb eine geringe Restbeweglichkeit, infolge der Biegebeanspruchung kann ohne Spondylodese ein Implantatversagen resultieren.
    Notes: Summary Defects of the dorsal and ventral ligament complexes of the lumbar spine results to an instability of the functional spinal unit. For the prognosis of secondary instability due to disko-ligamentous injuries the functional insufficiency of the lasting scars is a larger problem than the primar loss of osseous stability with fast healing tendency. The main goal of the present biomechanical study in vitro was to demonstrate the different grades of instability in the correlation to progressive disko-ligamentous defects as well as stabilisation through dynamic and static procedures. With a transpedicular screw-ringband-system the segmental function was preserved and instability was abolished. After rigid instrumentation with a fixateur intern remained a residual range of motion due to which can result refuse to bending moments without spondylodesis in an implant failure.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of orthopaedic and trauma surgery 103 (1984), S. 85-95 
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Für 18 Elemente wurde die Spurenelementzusammensetzung menschlicher Gewebe (Gelenkkapsel des Hüftgelenks und Fascia lata) mit Hilfe instrumenteller Neutronenaktivierungsanalyse vor and nach Anwendung von Totalendoprothesen des Hüftgelenks aus Kobalt-Chrom-Legierungen untersucht. Die Gewebe aus der Umgebung der Implantate zeigten extreme Belastungen mit Korrosionsprodukten der Metalle (Co, Cr, Ni) sowie mit Zr, Hf und Ba aus den Knochenzementen. Die Gewebe aus größer Entfernung zum Implantat zeigten niedrigere, jedoch noch signifikante Belastung. Sogar nich in den Implantat-Materialen enthaltene essentielle Spurunelemente ware in ihrer Häufigkeit nach Implantation verändert. Um die korrosive Auflösung der Liegerungsbestandteile in biologischen Medien zu untersuchen, wurde die Passierung von Co-Cr-Legierungen mit Hilfe der Trace-Technik untersucht. Dabei wurde Ringer-Lösung als einfaches Modell für die Körperflüssigkeiten gewählt. Der Passivierungsprozeß dauerte mehr als 2 Monat und war von einer selektiven Auflösung der Legierungsbestandtiele in der Reihenfolge Ni 〉 Co ∼ Fe 〉 Mo 〉 Cr begleitet. Ein Vergleich der Gewebeanalysen mit den Korrosionsexperimente zeigte, daß die Verteilung der Korrosionsprozeß, als auch durch die biochemischen Eigenschaften der Legierungsbestandteile bestimmt werden.
    Notes: Summary Using instrumental neutron activation analysis, the concentrations of 18 elements were studied in human articular capsule and fascia lata before and after application of total endoprostheses of the hip joint made of cobalt-chromium alloys. Tissues from the vicinity of the implant showed extreme burdening by corrosion products (Co, Cr, Ni), as well as by Zr, Hf, and Ba from the bone cements. Tissues more distant from the implants exhibited lower, but still significant burdening. Moreover, some essential trace elements not contained in the implant materials were changed in the tissues after implantation. In order to clarify the dissolution of alloy constituents in biological media, the passivation of cobalt-chromium alloy was investigated by tracer techniques using Ringer's solution as a simple model of the body fluids. The passivation process lasted for more than 1 month and was accompanied by a selective dissolution of the alloys constituents in the order Ni 〉 Co ≈ Fe 〉 Mo 〉 Cr. A comparison of the tissue analyses with the corrosion experiments demonstrates that the distribution patterns of the corrosion products in the tissues are influenced by both the corrosion process and the biochemical properties of the corrosion products.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International orthopaedics 23 (1999), S. 337-340 
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé  Dans cette analyse clinique prospective on a utilisé le clou Gamma comme fixation après l´ostéotomie intertrochantérienne pour la coxarthrose. 31 ostéotomies intertrochantériennes (varus, valgus et complexes) furent stabilisées par le clou Gamma. Deux semaines après l´opération les patients pouvaient charger l´ostéosynthèse de tout leur poids. Après un suivi moyen de 25,6 (13 à 42) mois, 29 ostéotomies étaient consolidées. Deux patients ne sont pas revenus. Il n´y avait ni fractures du fémur ni douleurs de cuisse.
    Notes: Abstract  In this study the Gamma nail was used for fixation after intertrochanteric osteotomy in osteoarthritis. In 31 patients varus, valgus and complex intertrochanteric osteotomies were stabilized. The patients were allowed full weight bearing 2 weeks postoperatively. After a mean follow-up of 25.6 (13–42) months 29 osteotomies were healed. Two patients were lost to follow-up. No femoral shaft fractures or thigh pain occurred.
    Type of Medium: Electronic Resource
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