Operative Eingriffe an Hand und Handgelenk

Zusammenfassung: Trotz der heute zur Verfügung stehenden Biologika bleiben das synovialitisch bedingte Karpaltunnelkompressionssyndrom, das Caput-ulnae-Syndrom oder palmar betonte Tenosynovialitiden mit drohenden Sehnenrupturen dringliche chirurgische Indikationen an der Hand. Die diagnostische und therapeutische Synovektomie zur Diagnose- und Therapieoptimierung behält ihren Stellenwert, nach Möglichkeit bevor radiologisch fassbare Destruktionen auftreten. Balance- oder gelenkstabilisierende Operationen müssen vor der Destruktion der Gelenke angeboten werden. Wird dieser Zeitpunkt verpasst, so können am Handgelenk meist nur noch Teil- oder komplette Arthrodesen, an den Grundgelenken Arthroplastiken und an den Endgelenken Arthrodesen durchgeführt werde

Physics of the Preparation and Observation of Specimens that Involve Cryoprocedures

With this introductory chapter we attempt a synthesis of old and new knowledge of the physical principles that govern cryomethods. Interface phenomena determine the increase or decrease of the number of particles observed in frozen-hydrated suspensions because they occupy the air-liquid interface according to their specific balance of hydrophobic versus hydrophilic properties. Biological macromolecules are surrounded by organised water, the hydration shell, that prevents them from sticking to each other. Partial or complete removal of these hydration shells by freeze-drying or freeze-substitution leads to collapses or aggregations. The solvent-induced aggregation is usually decreased by prior cross-linking with adequate chemical fixatives. A new finding is that aggregations are also decreased with lower temperatures. This al lows us, for example, to preserve DNA-containing plasma from coarse aggregation even in cases where it has not been previously crosslinked. When rapidly freezing a physiologically homogeneous population of bacterial cells without added cryoprotectants we find a 10-20 μm thick layer of cells without ice crystal formation. In deeper layers an increasing proportion of cells exhibits crystallization damage, although some cells are still well preserved. Treatment of cells with aqueous solutions of OsO4 and/or uranyl acetate leads to 10-20 % (w/w) heavy metal deposit. Direct staining of sections of resin embedded material results in 10 times more deposit. The location of these deposited metals is at first unknown and is best visualized through a comparison with totally unstained material. Sufficient contrast is achieved with the dark field, or the ratio-contrast mode of imaging. The latter has the advantage of giving less weight to thickness variations than does the former. When observing fully unstained thin sections by ratio contrast the influence of the surface reliefs is thereby virtually eliminated. With CTEM the dark field mode requires too great a dose to use it successfully on frozen-hydrated material. With STEM this is possible for both dark field and ratio contrast

Low Temperature Embedding

The Lowicryl resins K4M and HM20 are methacrylate/acrylate based formulations which can re used for embedding biological material at low temperature in conjunction with either the progressive lowering of temperature (PLT) technique or with freeze-substitution. The resins are applicable over a very extended temperature range, approximately 210°K to 340°K. Even lower temperatures down to ca. 190°K can be reached with two new resins, K11M and HM23. Test embeddings of unfixed material after freeze-substitution have given promising results which could re useful for imnunocytochemical labeling. Lipid extraction is small or absent when the two new resins are used in combination with freeze-substitution

Modeling of the degradation of poly(ethylene glycol)-co-(lactic acid)-dimethacrylate hydrogels

Because of their similarity with extracellular matrix, hydrogels are ideal substrates for cell growth. Hydrogels made of synthetic polymers are excellent alternatives to natural ones and offer the key advantage of precisely controllable degradation times. In this work, hydrogels have been prepared from modified poly(ethylene glycol) macromonomers, functionalized on both ends first with a few lactic acid units, and then with methacrylate groups. A library of hydrogels has been prepared using free- radical polymerization of the macromonomers, by changing both the macromonomer concentration and their type, i.e., the number of lactic acid repeating units. The degradation kinetics of these hydrogels, caused by the hydrolysis of the lactic acid units, have been carefully monitored in terms of swelling ratio, mass loss, and Young’s modulus. A complete mathematical model, accounting for hydrogel degradation, swelling, and reverse gelation, has been developed and used to predict all the measured quantities until complete disappearance of the gels. The model is capable of accurately predicting the time evolution of all the properties investigated experimentally. To the best of our knowledge, this is the first study where such a systematic comparison between model predictions and experimental data is presented

Fibromatosis of the Plantar Fascia: Diagnosis and Indications For Surgical Treatment

Plantar fibromatosis is a rare, benign lesion involving the plantar aponeurosis. Eleven patients (13 feet) underwent 24 operations, including local excision, wide excision, or complete plantar fasciectomy. Clinical results were evaluated retrospectively. There were no differences among the subgroups in postoperative complications. Two primary fasciectomies did not recur. Three of six revised fasciectomies, seven of nine wide excisions, and six of seven local excisions recurred. Our results indicate that recurrence of plantar fibromatosis after surgical resection can be reduced by aggressive initial surgical resection

A Bio-Inspired Swellable Microneedle Adhesive for Mechanical Interlocking with Tissue

Achieving significant adhesion to soft tissues while minimizing tissue damage poses a considerable clinical challenge. Chemical-based adhesives require tissue-specific reactive chemistry, typically inducing a significant inflammatory response. Staples are fraught with limitations including high-localized tissue stress and increased risk of infection, and nerve and blood vessel damage. Here, inspired by the endoparasite Pomphorhynchus laevis which swells its proboscis to attach to its host’s intestinal wall, we have developed a biphasic microneedle array that mechanically interlocks with tissue through swellable microneedle tips, achieving ~ 3.5 fold increase in adhesion strength compared to staples in skin graft fixation, and removal force of ~ 4.5 N/cm2 from intestinal mucosal tissue. Comprising a poly(styrene)-block-poly(acrylic acid) swellable tip and non-swellable polystyrene core, conical microneedles penetrate tissue with minimal insertion force and depth, yet high adhesion strength in their swollen state. Uniquely, this design provides universal soft tissue adhesion with minimal damage, less traumatic removal, reduced risk of infection and delivery of bioactive therapeutics

The CERN PS multi-turn extraction based on beam splittting in stable islands of transverse phase space: Design Report

Since 2001 considerable effort has been devoted to the study of a possible replacement of the continuous-transfer extraction mode from the PS to the SPS. Such an approach, called Multi-Turn Extraction (MTE), is based on capture of the beam inside stable islands of transverse phase space, generated by sextupoles and octupoles, thanks to a properly chosen tune variation. Both numerical simulations and measurements with beam were performed to understand the properties of this new extraction mode. The experimental study was completed at the end of 2004 and by the end of 2005 a scheme to implement this novel approach in the PS machine was defined and its performance assessed. This design report presents the outcome of the studies undertaken both in terms of technical issues as well as of resources necessary to implement the proposed scheme