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Implant Loosening (implant + loosening)
Selected AbstractsSoluble and particulate Co-Cr-Mo alloy implant metals activate the inflammasome danger signaling pathway in human macrophages: A novel mechanism for implant debris reactivityJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 7 2009Marco S. Caicedo Abstract Immune reactivity to soluble and particulate implant debris remains the primary cause of aseptic inflammation and implant loosening. However, the intracellular mechanisms that trigger immune cells to sense and respond to exogenous nonbiological agents such as metal particles or metal ions released from orthopedic implants remain unknown. Recent studies in immunology have outlined the importance of the intracellular inflammasome complex of proteins in sensing danger/stress signals triggered by nonbiological agents in the cytosol of macrophages. We hypothesized that metal implant debris can activate the inflammasome pathway in macrophages that causes caspase-1-induced cleavage of intracellular pro-IL-1, into its mature form, resulting in IL-1, secretion and induction of a broader proinflammatory response. We tested this hypothesis by examining whether soluble cobalt, chromium, molybdenum, and nickel ions and Co-Cr-Mo alloy particles induce inflammasome- mediated macrophage reactivity. Our results demonstrate that these agents stimulate IL-1, secretion in human macrophages that is inflammasome mediated (i.e., NADPH-, caspase-1-, Nalp3-, and ASC-dependent). Thus, metal ion- and particle-induced activation of the inflammasome in human macrophages provides evidence of a novel pathway of implant debris-induced inflammation, where contact with implant debris is sensed and transduced by macrophages into a proinflammatory response. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 847,854, 2009 [source] THA loading arising from increased femoral anteversion and offset may lead to critical cement stressesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2003Ralf U. Kleemann Abstract Aseptic loosening of artificial hip joints is believed to be influenced by the design and orientation of the implant. It is hypothesised that variations in implant anteversion and offset lead to changes in the loading of the proximal femur, causing critical conditions to both the bone and cement. The goal of this study was therefore to analyse the role of these parameters on loading, bone strains and cement stresses in total hip arthroplasty (THA). A validated musculo-skeletal model was used for the analysis of muscle and joint contact forces during walking and stair climbing. Two different anteversion angles (4° vs. 24°) and prostheses offsets (standard vs. long) were analysed. The loads for each case were applied to a cemented THA finite element model. Generally, stair climbing caused higher bone strains and cement stresses (max. +25%) than walking. Variations in anteversion and offset caused changes in the loading environment, bone strain distribution and cement stresses. Compared to the standard THA configuration, cement stresses were raised by increasing anteversion (max. +52%), offset (max. +5%) and their combination (max. +67%). Femoral anteversion, offset and their combination may therefore lead to an increased risk of implant loosening. Analyses of implant survival should consider this as a limiting factor in THA longevity. In clinical practice, implant orientation, especially in regard to pre- and post-operative anteversion, should be considered to be more critical. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] The role of osteoclast differentiation in aseptic loosening,JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2002Edward M. Greenfields The major cause of orthopaedic implant loosening is thought to be accelerated osteoclastic bone resorption due to the action of cytokines produced in response to phagocytosis of implant-derived wear particles. This accelerated osteoclastic bone resorption could be due to increases in any of the following processes: recruitment of osteoclast precursors to the local microenvironment, differentiation of precursors into mature multinucleated osteoclasts, activation of mature osteoclasts, and/or survival of osteoclasts. Our studies have focused on differentiation and survival to complement work by others who have focused on recruitment of precursors and activation. Taken together, our studies and those of other investigators provide strong evidence that increased recruitment of osteoclast precursors and their subsequent differentiation play major roles in wear particle-induced osteolysis. In contrast, increased osteoclast activation and survival appear to play minor roles. These studies suggest that development of therapeutic interventions that reduce either recruitment or differentiation of osteoclast precursors would improve the performance of orthopaedic implants. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Bone healing performance of electrophoretically deposited apatite,wollastonite/chitosan coating on titanium implants in rabbit tibiaeJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 7 2009Smriti Sharma Abstract Bone healing of tibial defect in rabbit model was used to evaluate a composite coating of apatite,wollastonite/chitosan on titanium implant. This coating has been developed to overcome the shortcomings, such as implant loosening and lack of adherence, of uncoated titanium implant. An electrophoretic deposition technique was used to coat apatite,wollastonite/chitosan on titanium implants. The present study was designed to evaluate the bone response of coated as compared to uncoated titanium implants in an animal model. After an implantation period of 14 (group A), 21 (group B), 35 (group C) and 42 days (group D), the bone,implant interfaces and defect site healing was evaluated using radiography, scintigraphy, histopathology, fluorescence labeling and haematology. Radiography of defect sites treated with coated implants suggested expedited healing. Scintigraphy of coated implant sites indicated faster bone metabolism than uncoated implant sites. Histopathological examination and fluorescence labeling of bone from coated implant sites revealed higher osteoblastic activity and faster mineralization. Faster bone healing in the case of coated implant sites is attributed to higher cell adhesion on electrostatically charged chitosan surfaces and apatite,wollastonite-assisted mineralization at bone,implant interfaces. Haematological studies showed no significant differences in haemoglobin, total erythrocyte and leukocyte counts, done using one way-ANOVA, during the entire study period. Our results show that AW/chitosan-coated implants have the advantages of faster bone healing, increased mechanical strength and good bone,implant bonding. Copyright © 2009 John Wiley & Sons, Ltd. [source] Assessment of Five Interleukins in Human Synovial Fluid as Possible Markers for Aseptic Loosening of Hip ArthroplastyARTIFICIAL ORGANS, Issue 7 2009Alina Beraudi Abstract One of the most important factors that seems to be involved in total hip replacement is periprosthetic osteolysis. As it is well documented that several interleukins (ILs) are triggered in periprosthetic osteolysis, this article investigates the role of five ILs in primary and replacement total hip arthroplasty, understanding if one of them can also predict hip implant loosening, secondary surgery, and prosthesis breakage. The levels of IL-1,, 1,, 6, 8, and 10 in synovial fluid were examined, using a high sensitivity enzyme-linked immunosorbent assay (ELISA) test kit (Pierce Biotechnology, Inc., Rockford, IL, USA) to determine whether these cytokines could be used as markers of enhanced periprosthetic osteolysis, leading to aseptic loosening of total/partial hip arthroplasty or revision surgery. Synovial fluid was harvested from 23 patients undergoing primary total hip arthroplasty and 35 patients undergoing total/partial hip revision due to aseptic loosening. In the revision group, four cases had suffered a prosthesis fracture and five were second revisions. ILs 6 and 8 were significantly higher in the revisions (305 and 817 pg/mL) compared with the primary arthroplasties (151 and 151 pg/mL), including cases with prosthesis fracture and those requiring a second revision. IL-10 levels were lower (not significantly) in second revision samples compared with those of revision samples. IL-1, levels were significantly higher in prosthesis fracture samples compared with those of all the other revision samples. No statistically significant differences in IL levels were found between osteoarthritis samples and those of other diseases. These results are a step forward to elucidating the complex network of events that are involved in loosening of hip implants. [source] | ||||||||||