Anatomische und biomechanische Überlegungen zur Sprunggelenkprothetik

Zusammenfassung: Der Erfolg des prothetischen Ersatzes des oberen Sprunggelenks (OSG) dürfte wesentlich davon abhängen inwieweit die physiologischen Verhältnisse des Gelenks erhalten bleiben, respektive wiederhergestellt wurden. Je mehr das Design der Prothese der physiologischen Anatomie entspricht, je korrekter die Achsenstellung des Rückfußes und je ausgeglichener die Bandspannung ist, desto besser werden die normalen kinematischen Verhältnisse des OSG nachgeahmt. Dadurch können unphysiologische Kräfte vermindert werden, die zu Schmerzen, Verschleiß und zu einem frühen Implantatversagen führen können. In diesem Artikel sind die zur Sprunggelenkprothetik notwendigen anatomischen und biomechanischen Grundlagen zusammengestell

Die HINTEGRA-Sprunggelenkprothese: Kurz- und mittelfristige Erfahrungen

Zusammenfassung: Dieser Artikel soll das spezifische Design der HINTEGRA®-Sprunggelenkprothese darstellen und die kurz- und mittelfristigen Ergebnisse klinisch und radiologisch aufarbeiten sowie hinsichtlich der Lernkurve und Revisionsoperationen kritisch analysieren. Von 278 zwischen Mai 2000 und August 2004 operierten Fällen konnten 271Sprunggelenke [261Patienten, 133Männer, 128Frauen; Alter 58,4 (25-90) Jahre] nach 36,1 (12-64) Monaten klinisch und radiologisch nachkontrolliert werden. Die Operationsindikation war in 206Fällen (76,0%) eine posttraumatische Osteoarthrose, in 34Fällen (12,5%) eine Arthritis im Rahmen einer systemischen Erkrankung und in 31Fällen (11,5%) eine primäre Arthrose. Neben 4 perioperativen und 19 frühpostoperativen Komplikationen kam es in 40Fällen (14,8%) zu einer Spätkomplikation; davon waren 22Komplikationen (8,2%) nicht implantatbezogen und 18Komplikationen (6,6%) implantatbezogen. In 39Fällen (14,4%) war eine Revisionsoperation erforderlich, davon in 5Fällen (1,8%) eine Konversion in eine OSG-Arthrodese. Sämtliche 34Fälle zeigten nach der erfolgreichen Revision bezüglich Verlauf und Ergebnis keine Unterschiede zu den komplikationsfreien 231Fällen. Der AOFAS-Hindfoot-Score verbesserte sich von präoperativ 40,3 (14-61) auf 85,0 (44-100) Punkte. Radiologisch zeigten sich alle verbleibenden 266 Tibiakomponenten stabil. 12 Taluskomponenten (4,4%) waren zu weit posterior implantiert und lagen nicht ideal auf dem posterioren Talus auf. Die Konzepte der minimalen Knochenresektion, möglichst großer Knochenabstützung, optimalen ligamentären Balance und minimalen Stressbelastungen in und um die Prothese zeigte sich hinsichtlich Verankerung im tibialen und talaren Knochen sowohl bei der primären Arthroplastik wie auch bei Revisionen erfolgreich. Die Lernkurve war kurz und steil, und die Mehrzahl der 18 implantatbezogenen Revisionen traten in den ersten Fällen auf. Trotz dem hohen Anteil von posttraumatischen Arthrosen mit häufigen Weichteilschäden waren die Ergebnisse ermutigend und lagen im Bereiche von anderen Erfahrungsberichten. Dies nährt die Hypothese, dass in der Arthroplastik des oberen Sprunggelenks (OSG) anatomische Oberflächen und exakte Positionierung der Komponenten für den Erfolg entscheidend sin

Monitoring the Myosin Crossbridge Cycle in Contracting Muscle:Steps towards ‘Muscle the Movie’.

Some vertebrate muscles (e.g. those in bony fish) have a simple lattice A-band which is so well ordered that low-angle X-ray diffraction patterns are sampled in a simple way amenable to crystallographic techniques. Time-resolved X-ray diffraction through the contractile cycle should provide a movie of the molecular movements involved in muscle contraction. Generation of ‘Muscle—The Movie’ was suggested in the 1990s and since then efforts have been made to work out how to achieve it. Here we discuss how a movie can be generated, we discuss the problems and opportunities, and present some new observations. Low angle X-ray diffraction patterns from bony fish muscles show myosin layer lines that are well sampled on row-lines expected from the simple hexagonal A-band lattice. The 1st, 2nd and 3rd myosin layer lines at d-spacings of around 42.9 nm, 21.5 nm and 14.3 nm respectively, get weaker in patterns from active muscle, but there is a well-sampled intensity remnant along the layer lines. We show here that the pattern from the tetanus plateau is not a residual resting pattern from fibres that have not been fully activated, but is a different well-sampled pattern showing the presence of a second, myosin-centred, arrangement of crossbridges within the active crossbridge population. We also show that the meridional M3 peak from active muscle has two components of different radial widths consistent with (i) active myosin-centred (probably weak-binding) heads giving a narrow peak and (ii) heads on actin in strong states giving a broad peak

Uso de espectrofotometria como alternativa para a diminuição da produção de resíduos de cromo na quantificação do carbono da biomassa microbiana.

Tem como objetivo: avaliar método alternativo de determinação do Carbono da Biomassa Microbiana (C-BMS) para a diminuição do volume de resíduos gerados com a digestão do dicromato. Reduzir a concentração de cromo utilizada na solução digestora sem comprometimento na recuperação dos valores de C-BMS nas amostras. Agilizar o processo analítico, diminuindo o tempo gasto na determinação do C-BMS.bitstream/CNPAF-2010/29765/1/doc-248.pd

Doses de molibdênio em arroz irrigado em solo de várzea.

Esse estudo teve como objetivo avaliar em casa de vegetação a resposta do arroz irrigado à aplicação de Mo

The topographical relationship between visual field loss and peripapillary retinal nerve fibre layer thinning arising from long-term exposure to vigabatrin

Background The antiepileptic drug vigabatrin is associated with characteristic visual field loss (VAVFL) and thinning of the peripapillary retinal nerve fibre layer (PPRNFL); however, the relationship is equivocal. Objective The aim of this study was to determine the function–structure relationship associated with long-term exposure to vigabatrin, thereby improving the risk/benefit analysis of the drug. Methods A cross-sectional observational design identified 40 adults who had received long-term vigabatrin for refractory seizures, who had no evidence of co-existing retino-geniculo-cortical visual pathway abnormality, and who had undergone a standardized protocol of perimetry and of optical coherence tomography (OCT) of the PPRNFL. Vigabatrin toxicity was defined as the presence of VAVFL. The function–structure relationship for the superior and inferior retinal quadrants was evaluated by two established models applicable to other optic neuropathies. Results The function–structure relationship for each model was consistent with an optic neuropathy. PPRNFL thinning, expressed in micrometres, asymptoted at an equivalent visual field loss of worse than approximately − 10.0 dB, thereby preventing assessment of more substantial thinning. Transformation of the outcomes to retinal ganglion cell soma and axon estimates, respectively, resulted in a linear relationship. Conclusions Functional and structural abnormality is strongly related in individuals with vigabatrin toxicity and no evidence of visual pathway comorbidity, thereby implicating retinal ganglion cell dysfunction. OCT affords a limited measurement range compared with perimetry: severity cannot be directly assessed when the PPRNFL quadrant thickness is less than approximately 65 µm, depending on the tomographer. This limitation can be overcome by transformation of thickness to remaining axons, an outcome requiring input from perimetry

Molecular Packing in Network-Forming Collagens

Collagen is the most abundant protein among vertebrates and occurs in virtually all multicellular animals. Collagen molecules are classified into 21 different types and differ in their sequence, weight, structure, and function, but they can be broadly subdivided into families. Type IV, VI, VIII, X, and dogfish egg case collagens belong to the network-forming family. Here, we summarise what is known about the way these collagen molecules pack to form networks. In addition the main structural characteristics of the network-forming collagens are compared and discussed

Avaliação de biossegurança de transgênico por DGGE: estudo de caso do feijão VMDF, evento M1-4.

O objetivo deste estudo foi avaliar possíveis efeitos da modificação genética, evento M1-4, sobre organismos não-alvos, estudando a comunidade bacteriana rizosférica