Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0220723 (PCA)
 4,687 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Twelve uncemented, artificial patellar components clinically and radiologically without signs of loosening after an implantation period of 9-48 Months were investigated histologically and microradiographically. The components correspond to the system GSB-"old", GSB-"new", PCA and APS. Within the observed implantation period the artificial patellar components GSB-"old", GSB-"new" and PCA showed severe patho-morphological changes of the surrounding tissue and point to loosening. The dowel system according to APS shows after the longest period of time of 14 Months morphologically a fully bony encasement with wide spread direct contacts between the living bone and the metallic Titanium surface. The observation points urgently to the fact, that Polyethylene must not be in direct contact with the bony bed. On the basis of the patho-morphological reactions a partial armament of the polyethylene surface with metallic structures must be rejected as a general principle.
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PMID:[Comparative morphological studies on the incorporation of various cementless implanted artificial patellas]. 149 54

The membranes surrounding seven loose cementless acetabular implants were shown to contain polyethylene particles, birefringent in polarised light. Three of these implants were made of titanium alloy and the membranes around these contained titanium particles as well. There was no metallosis around the four implants made of chromium-cobalt-steel alloy. Both titanium and polyethylene particles caused migration, adherence and phagocytosis of CD11b-positive, peroxidase-negative macrophages. There were no histological signs of activation of the specific immune response; neither interleukin-2 receptor-positive activated T cells nor PCA-1 plasmablasts/plasma cells were present in the tissues. In cases of simple loosening, resident mesenchymal fibroblast-like cells were active. In aggressive granulomatosis, there were many macrophages and multinucleated giant cells but little fibroblast reaction. The clinical relevance of the findings is that the use of cementless prostheses is not a guarantee against adverse tissue reactions.
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PMID:Immunopathological response to loose cementless acetabular components. 199 72

Plasma spray coatings on titanium alloy total hip replacements (THRs) provide a viable alternative to sintered bead or diffusion-bonded fiber metal ingrowth surfaces. The plasma spray process enables the titanium alloy implant to retain 90% of its fatigue strength, as opposed to less than 50% for sintered or diffusion-bonded cementless devices. Laboratory and clinical evidence suggest that plasma spray cementless THRs perform as well, if not better, than other cementless implants. Clinical trials have demonstrated the superiority of a plasma spray cementless THR (Mallory-Head) over a sintered bead cementless THR (PCA) and the equivalent results to a cemented THR. Plasma spray coatings on titanium alloy hip replacements provide a safe, predictable coating for cementless fixation of THRs in the short to medium range of follow-up periods.
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PMID:Ingrowth surfaces. Plasma spray coating to titanium alloy hip replacements. 811 92

Initial stability is necessary for permanent fixation of acetabular cups. Biologic reactions to submicron particles such as localized bone resorption may lead to implant failure. The aim of the study was to evaluate different fixation principles of acetabular components. Four randomized studies and one case-control study were performed to evaluate different bone cements, different cup designs, use of ceramic coating or not, different type of screws and the need of additional screw fixation or not. Radiostereometry (RSA) makes it possible to analyze small translations and rotations of implants with a high accuracy. This method is suitable for evaluation of early stability and was used in four of the studies. Clinical and radiological follow-up were performed regularly. The cements were tested in the laboratory. 30 patients (mean age 71 years, range: 63-76) received total hip arthroplasties and were randomised to fixation with Boneloc (14) or Palacos cum gentamicin (16) bone cement. The curing temperature was 23 degrees lower for the Boneloc cement but the tensile strength was reduced and the elastic modulus was lower compared to Palacos. The proximal cup migration was greater in the Boneloc group up to 12 months (p 0.04) and these cups migrated medially in contrast to a small lateral migration seen in the Palacos group (p 0.04). Radiolucencies were more pronounced in the Boneloc group at 12 months (p 0.04). 155 patients (171 hips, mean age 50 years, range: 24-64) received uncemented hip arthroplasties. 84 hips were randomised to the PCA and 87 to the Harris-Galante I designs. The 10-year survival rates were 85% for the PCA and 99% for the Harris-Galante I cups (revision as end-point). The wear and clinical results did not differ. 43 patients (mean age 60 years, range 44-68) received uncemented porous cups with a titanium mesh in pure titanium (Harris-Galante II) and were randomised to additional fixation with either biodegradable screws (23, poly-L-lactic acid, PLLA) or screws made of titanium alloy (20). Increased proximal and medial-lateral translations (p 0.02, 0.04) but less rotation around the longitudinal axis (p 0.04) were seen in the PLLA group up to 2 years. There were also more pronounced radiolucencies anteriorly in this group at 2 years. The clinical results did not differ. 23 uncemented porous cups (Harris-Galante II) with hydroxyapatite-tricalciumphosphate coating (HA/TCP) were pair-wise matched to uncoated cups. Up to 2 years, decreased rotations around the horizontal axis were recorded in the HA/TCP-coated cups. Central postoperative gaps were more frequently seen in the HA/TCP group (p < 0.01), but at 2 years radiolucencies were more pronounced in the uncoated group (p < 0.01). The wear and clinical results did not differ. 62 patients (64 hips, mean age 56 years, range: 32-75) were randomized to porous Trilogy cups with (30) and without (34) cluster holes for additional screw fixation. Up to 2 years there were no differences in migration, wear, radiographic findings or clinical results. In conclusion Boneloc cement was associated with poor fixation due to inferior mechanical properties. The PLLA screws did not provide sufficient stability. Unacceptably high failure rates were recorded for the PCA cup. HA/TCP coating improved the fixation and the interface of porous cups. HA/TCP coated porous cups can be fixed without adjunctive screw fixation.
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PMID:The acetabular component in total hip arthroplasty. Evaluation of different fixation principles. 1057 4

Four types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended with Geobacter sulfurreducens strain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, to Geobacter sulfurreducens strain PCA. Other bacterial species were also detected in the system, such as a Propionicimonas-related species that was dominant in the anodic liquid and Pseudomonas-, Clostridium-, Desulfovibrio-, Azospira-, and Aeromonas-related species.
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PMID:Microbial communities and electrochemical performance of titanium-based anodic electrodes in a microbial fuel cell. 2113 13