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Investigation of the in-vitro loading on an artificial spinal disk prosthesis
Spinal diseases imposes considerable burden to both patients and society. In recent years, much surgical efforts have been made in advancing the treatment of neck and back pain. Of particular prominence is the increasing clinical acceptance and use of intervertebral artificial disk prosthesis for the treatment of discogenic back pain. Despite this increased use of such disks, their in-vivo monitoring remains rudimentary. In an effort to develop an intelligent artificial spinal disk where the in-vivo loading of the spine can by studied for the first time an experimental set up has been created in order to initially study the in-vitro loading on an artificial disc prosthesis. Eight strain gauges and two piezoresistive sensors were used and placed suitably in the artificial disk prosthesis. The results from the in-vitro loading showed linear relationship between loading and the outputs from the sensors with good repeatability and less hysteresis
Sex differences in the morphological failure patterns following hip resurfacing arthroplasty
<p>Abstract</p> <p>Background</p> <p>Metal-on-metal hybrid hip resurfacing arthroplasty (with a cementless acetabular component and a cemented femoral component) is offered as an alternative to traditional total hip arthroplasty for the young and active adult with advanced osteoarthritis. Although it has been suggested that women are less appropriate candidates for metal-on-metal arthroplasty, the mechanisms of prosthesis failure has not been fully explained. While specific failure patterns, particularly osteonecrosis and delayed type hypersensitivity reactions have been suggested to be specifically linked to the sex of the patient, we wished to examine the potential influence of sex, clinical diagnosis, age of the patient and the size of the femoral component on morphological failure patterns in a large cohort of retrieved specimens following aseptic failure of hip resurfacing arthroplasty.</p> <p>Methods</p> <p>Femoral remnants retrieved from 173 hips with known patient's sex were morphologically analyzed for the cause of failure. The results were compared with the control group of the remaining 31 failures from patients of unknown sex. The odds ratios (OR) and 95% confidence intervals (CI) of the following morphologically defined variables were calculated using logistic regression analysis: periprosthetic fractures (n = 133), osteonecrosis (n = 151), the presence of excessive intraosseous lymphocyte infiltration (n = 11), and interface hyperosteoidosis (n = 30). Logistic regression analysis was performed both unadjusted and after adjustment for sex, age, the size of the femoral component, and preoperative clinical diagnosis.</p> <p>Results</p> <p>Femoral remnants from female patients had a smaller OR for fracture (adjusted OR: 0.29, 95% CI 0.11, 0.80, <it>P </it>for difference = 0.02) and for the presence of osteonecrosis (adjusted OR: 0.16, 95% CI 0.04, 0.63, <it>P </it>for difference = 0.01). However, women had a higher OR for both the presence of excessive intraosseous lymphocyte infiltration (adjusted OR: 10.22, 95% CI 0.79, 132.57, <it>P </it>for difference = 0.08) and interface hyperosteoidosis (adjusted OR: 4.19, 95% CI 1.14, 15.38, <it>P </it>for difference = 0.03).</p> <p>Conclusions</p> <p>Within the limitations of this study, we demonstrated substantial sex differences in distinct failure patterns of metal-on-metal hip resurfacing. Recognition of pathogenically distinct failure modes will enable further stratification of risk factors for certain failure mechanisms and thus affect future therapeutic options for selected patient groups.</p
Osteonecrosis following resurfacing arthroplasty: A clinical positron emission tomography study of 14 cases
Background and purpose One of the main concerns regarding resurfacing arthroplasty is the viability of the remaining part of the femoral head, and the postoperative risk of a femoral neck fracture or collapse. In contrast to radiographic methods, positron emission tomography using the radiotracer [18F]-fluoride (Fluoride-PET) enables us to visualize the viability of bone in the remaining part of the head, despite the presence of the covering metal component
Incorporating corrosion measurement in hip wear simulators: An added complication or a necessity?
Corrosion is not routinely considered in the assessment of the degradation or the lifetime of total hip replacement bearing surfaces. Biomechanical simulations are becoming ever more complex and are taking into account motion cycles that represent activities beyond a simple walking gait at 1 Hz, marking a departure from the standard ISO BS 14242. However, the degradation is still very often referred to as wear, even though the material loss occurs due to a combination of tribological and corrosion processes and their interactions. This article evaluates how, by incorporating real-time corrosion measurements in total hip replacement simulations, pre-clinical evaluations and research studies can both yield much more information and accelerate the process towards improved implants
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
Measurement of the Forward-Backward Asymmetry in the B -> K(*) mu+ mu- Decay and First Observation of the Bs -> phi mu+ mu- Decay
We reconstruct the rare decays , , and in a data sample
corresponding to collected in collisions at
by the CDF II detector at the Fermilab Tevatron
Collider. Using and decays we report the branching ratios. In addition, we report
the measurement of the differential branching ratio and the muon
forward-backward asymmetry in the and decay modes, and the
longitudinal polarization in the decay mode with respect to the squared
dimuon mass. These are consistent with the theoretical prediction from the
standard model, and most recent determinations from other experiments and of
comparable accuracy. We also report the first observation of the {\mathcal{B}}(B^0_s \to
\phi\mu^+\mu^-) = [1.44 \pm 0.33 \pm 0.46] \times 10^{-6}27 \pm 6B^0_s$ decay observed.Comment: 7 pages, 2 figures, 3 tables. Submitted to Phys. Rev. Let
Search for a New Heavy Gauge Boson Wprime with Electron + missing ET Event Signature in ppbar collisions at sqrt(s)=1.96 TeV
We present a search for a new heavy charged vector boson decaying
to an electron-neutrino pair in collisions at a center-of-mass
energy of 1.96\unit{TeV}. The data were collected with the CDF II detector
and correspond to an integrated luminosity of 5.3\unit{fb}^{-1}. No
significant excess above the standard model expectation is observed and we set
upper limits on . Assuming standard
model couplings to fermions and the neutrino from the boson decay to
be light, we exclude a boson with mass less than
1.12\unit{TeV/}c^2 at the 95\unit{%} confidence level.Comment: 7 pages, 2 figures Submitted to PR
Measurements of the properties of Lambda_c(2595), Lambda_c(2625), Sigma_c(2455), and Sigma_c(2520) baryons
We report measurements of the resonance properties of Lambda_c(2595)+ and
Lambda_c(2625)+ baryons in their decays to Lambda_c+ pi+ pi- as well as
Sigma_c(2455)++,0 and Sigma_c(2520)++,0 baryons in their decays to Lambda_c+
pi+/- final states. These measurements are performed using data corresponding
to 5.2/fb of integrated luminosity from ppbar collisions at sqrt(s) = 1.96 TeV,
collected with the CDF II detector at the Fermilab Tevatron. Exploiting the
largest available charmed baryon sample, we measure masses and decay widths
with uncertainties comparable to the world averages for Sigma_c states, and
significantly smaller uncertainties than the world averages for excited
Lambda_c+ states.Comment: added one reference and one table, changed order of figures, 17
pages, 15 figure
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