Current Issue : October - December Volume : 2014 Issue Number : 4 Articles : 6 Articles
Objective.This study was designed to explore relationships of resonance frequency analysis (RFA)ââ?¬â?assessed implant stability (ISQ\nvalues)with bonemorphometric parameters and bone quality in an ex vivomodel of dental implants placed inhumanfemoral heads\nand to evaluate the usefulness of this model for dental implant studies. Material and Methods. This ex vivo study included femoral\nheads from 17 patients undergoing surgery for femoral neck fracture due to osteoporosis (OP) (n = 7) or for total prosthesis joint\nreplacement due to severe hip osteoarthrosis (OA) (n = 10). Sixty 4.5 Ã?â?? 13mm Dentsply Astra implants were placed, followed by\nRFA. CD44 immunohistochemical analysis for osteocytes was also carried out. Results. As expected, the analysis yielded significant\neffects of femoral head type (OA versus OA) (P < 0.001), but not of the implants (P = 0.455) or of the interaction of the two factors\n(P = 0.848). Bonferroni post hoc comparisons showed a lower mean ISQ for implants in decalcified (50.33 Ã?± 2.92) heads than\nin fresh (66.93 Ã?± 1.10) or fixated (70.77 Ã?± 1.32) heads (both P < 0.001). The ISQ score (fresh) was significantly higher for those\nin OA (73.52 Ã?± 1.92) versus OP (67.13 Ã?± 1.09) heads. However, mixed linear analysis showed no significant association between\nISQ scores and morphologic or histomorphometric results (P > 0.5 in all cases), and no significant differences in ISQ values were\nfound as a function of the length or area of the cortical layer (both ???? > 0.08). Conclusion. Although RFA-determined ISQ values\nare not correlated withmorphometric parameters, they can discriminate bone quality (OP versus OA). This ex vivo model is useful\nfor dental implant studies....
A new incus-body driving type transducer relying on piezoelectric stack, with broad frequency bandwidth, is proposed for use\nin a middle ear implant. To aid the design process of this transducer, a coupling biomechanical model of the human middle ear\nand the piezoelectric transducer was established by reverse engineering technology. The validity of this model was confirmed by\ncomparing model predicted motions with experimental measurements. Based on this verified biomechanical model, the main\nparameters of the transducer were determined. And its power consumption was calculated. Finally, to verify the capability of the\ndesigned piezoelectric transducer, a human temporal bone experimental platform was built. And the dynamic characteristics and\nthe stimulated performance of the piezoelectric transducer were tested. The result showed that stapes displacement stimulated\nby the transducer excitation at 10.5V RMS was equivalent to that from acoustic stimulation at 100 dB SPL, which is an adequate\nstimulation to the ossicular chain. The corresponding power consumption is 0.31mW per volt of excitation at 1 kHz, which is low\nenough for the transducer to be used in a middle ear implant. Besides, this transducer demonstrates high performance at high\nfrequencies....
Rheumatoid arthritis is the leading cause of disability in young adults. Total knee arthroplasty has been successfully used to restore\nthe joint function. Due to small bone size, osteoporosis, and severe soft tissue disease, standard knee implant sometimes cannot\nbe directly applied clinically and patient-specific designs may be a more rational choice.The purpose of this study was to evaluate\nthe biomechanical behavior of a patient-specific knee implant. A three-dimensional finite element of total knee arthroplasty was\ndeveloped. The mechanical strength and the wear damage of the articular surfaces were analyzed. The results show that there exist\nhigh risks of component fracture and wear damage; the proposed implant design should be abandoned.The presurgery analysis is\nhelpful in avoiding the potential failure....
Background. Indication for rotating hinge (RH) total knee arthroplasty (TKA) includes primary and revision cases, with\ncontradictory results. The aimof this study was to report prospective early results of a new modular rotating hinge TKA (EnduRo).\nFor this implant several new design features and a new bearing material (carbon-fiber reinforced poly-ether-ether-ketone) have\nbeen developed. Furthermore, we tried to establish a new classification of failure modes for revision TKA. Methods. 152EnduRo\nrotating-hinge prostheses were implanted in two centers. In 90 patients a primary implantation has been performed and 62 patients\nwere revision cases. Knee Society Score (KSS), Western Ontario and McMaster Osteoarthritis Index (WOMAC), Oxford Knee\nScore (OKS), and Range of motion (ROM) were assessed before surgery, 3 months postoperatively, 12 months postoperatively, and\nannually thereafter. We defined 3 types of complications: Type 1, infection; type 2, periprosthetic complications; type 3, implant\nfailures. Results. KSS, WOMAC, OKS, and ROM revealed significant improvements between the preoperative and the follow-up\ninvestigations. There were 14 complications (9.2%) leading to revision surgery, predominantly type 2. Conclusion. Our study shows\nexcellent clinical results of the EnduRo TKA. Furthermore, no premature material failure or unusual biological response to the new\nbearing material could be detected....
Introduction.We introduce a rating tool that objectively evaluates the skills of surgical trainees performing cochlear implant surgery.\nMethods. Seven residents and seven experts performed cochlear implant surgery sessions from mastoidectomy to cochleostomy\non a standardized virtual reality temporal bone. A total of twenty-eight assessment videos were recorded and two consultant\notolaryngologists evaluated the performance of each participant using these videos. Results. Interrater reliability was calculated\nusing the intraclass correlation coefficient for both the global and checklist components of the assessment instrument. The overall\nagreement was high. The construct validity of this instrument was strongly supported by the significantly higher scores in the\nexpert group for both components. Conclusion. Our results indicate that the proposed assessment tool for cochlear implant surgery\nis reliable, accurate, and easy to use. This instrument can thus be used to provide objective feedback on overall and task-specific\ncompetency in cochlear implantation....
All of the over 1 million total joint replacements implanted in the US each year are expected to eventually fail after 15ââ?¬â??25 years\nof use, due to slow progressive subtle inflammation at the bone implant interface. This inflammatory disease state is caused by\nimplant debris acting, primarily, on innate immune cells, that is, macrophages. This slow progressive pathological bone loss or\nââ?¬Å?aseptic looseningââ?¬Â is a potentially life-threatening condition due to the serious complications in older people (>75 yrs) of total joint\nreplacement revision surgery. In some people implant debris (particles and ions from metals) can influence the adaptive immune\nsystem as well, giving rise to the concept of metal sensitivity. However, a consensus of studies agrees that the dominant form of this\nresponse is due to innate reactivity by macrophages to implant debris where both danger (DAMP) and pathogen (PAMP) signalling\nelicit cytokine-based inflammatory responses. This paper discusses implant debris induced release of the cytokines and chemokines\ndue to activation of the innate (and the adaptive) immune system and the subsequent formation of osteolysis. Different mechanisms\nof implant-debris reactivity related to the innate immune system are detailed, for example, danger signalling (e.g., IL-1????, IL-18, IL-\n33, etc.), toll-like receptor activation (e.g., IL-6, TNF-????, etc.), apoptosis (e.g., caspases 3ââ?¬â??9), bone catabolism (e.g., TRAP5b), and\nhypoxia responses (Hif1-????). Cytokine-based clinical and basic science studies are in progress to provide diagnosis and therapeutic\nintervention strategies....
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