Category:
Bunion; Midfoot/Forefoot
Introduction/Purpose:
The minimally-invasive Chevron-Akin (MICA) procedure for hallux valgus correction is an increasingly popular technique that has yielded ...comparable radiographic and clinical outcomes to open procedures3–5. Intraoperative radiation dosages for certain foot and ankle surgeries have been reported relative to the international occupational radioprotection thresholds6. In particular, the mean intraoperative radiation exposure during the MIS Scarf osteotomy has been reported to be 14-times greater than open osteotomy7. However, no study to date has reported on the intraoperative radiation exposure during MICA procedures in relation to that of open procedures.
Methods:
This is a retrospective comparative study from a single institution. Patients underwent a MICA (n=25) or open (n=40) hallux valgus correction by a single foot and ankle fellowship trained surgeon. To account for the learning curve8, the number of intraoperative fluoroscopy shots for the first 50 consecutive MICA procedures were analyzed, and the first 25 procedures were excluded. Four data points were retrieved from the mini C-arm, including 1) number of fluoroscopy shots taken; 2) total fluoroscopy time (s); 3) total radiation dose (mGy); and 4) total dose area product (DAP; mGy*cm2). Preoperative and postoperative radiographs were referenced to measure the hallux valgus (HVA) and intermetatarsal angles (IMA) as previously described.9 Categorical variables were compared using the chi-square test, and continuous variables were compared using Student’s t-test or the Mann-Whitney U test. Analysis of variance was used to determine the statistical significance of differences in the fluoroscopy data between groups.
Results:
The average total dose absorbed (4.00 vs. 1.34 mGy, p< 0.001), total fluoroscopy time (226 vs. 48.5 s, p< 0.001), and number of fluoroscopy shots (125 vs. 22.3, p< 0.001) were 2.9, 4.6, and 5.6 times greater in the MICA versus the open group, respectively. The total DAP (4.22 vs. 2.56 mGy*cm2, p=0.175) was 1.6 times greater in the MICA group but the difference was not statistically significant. The mean preoperative and postoperative HVA and IMA were greater in the MICA cohort compared to the open cohort. However, there was no statistical difference in change in HVA (MICA -17.43 vs. Open -20.05, p=0.125) or IMA (MICA -8.08 vs. open -9.31, p=0.11) between the two cohorts, with each resulting in normal postoperative angles.
Conclusion:
In this single surgeon series, the MICA procedure demonstrated significantly greater dose absorbed, total fluoroscopy time, and number of fluoroscopy shots compared to the open procedure. The extent of radiation exposure to the surgeon and the patient in relation to the radioprotection thresholds must be closely monitored to specify the health risks involved with this procedure.
The deconfined quark-gluon plasma (QGP) created in relativistic heavy-ion collisions enables the exploration of the fundamental properties of matter under extreme conditions. Noncentral collisions ...can produce strong magnetic fields on the order of 1018 G, which offers a probe into the electrical conductivity of the QGP. In particular, quarks and antiquarks carry opposite charges and receive contrary electromagnetic forces that alter their momenta. This phenomenon can be manifested in the collective motion of final-state particles, specifically in the rapidity-odd directed flow, denoted as v1(y). Here, we present the charge-dependent measurements of dv1/dy near midrapidities for π±, K±, and $p(\bar{p})$ in Au+Au and isobar $(^{96}_{44}Ru+^{96}_{44}Ru$ and $^{96}_{40}Zr+^{96}_{40}Zr)$ collisions at $\sqrt{s_{NN}}=200$ GeV, and in Au+Au collisions at 27 GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider. The combined dependence of the v1 signal on collision system, particle species, and collision centrality can be qualitatively and semi-quantitatively understood as several effects on constituent quarks. While the results in central events can be explained by the u and d quarks transported from initial-state nuclei, those in peripheral events reveal the impacts of the electromagnetic field on the QGP. Our data put valuable constraints on the electrical conductivity of the QGP in theoretical calculations.
To determine the trends and outcomes for treating primary rhegmatogenous retinal detachment (RRD) in a nationwide population-based study in Taiwan.
We collected admission data during the period of ...1997-2005, from the Taiwan National Health Insurance Research Database, a source that covers over 96% of Taiwan's 23 million citizens. Totally 28 911 patients with a first-time admission diagnosis of RRD (ICD-9-CM codes 361 to 361.07) and undergoing surgical treatment (scleral buckling (SB), pars plana vitrectomy (PPV), or their combination) were identified. The utilized operation type, 180-day readmission rate for recurrent retinal detachment, length of hospital stay, and admission charge were obtained. Contingency table/chi (2) test and t-test were employed for the statistical analysis.
Primary PPV (with or without SB) was a primary procedure in 47.3% of cases in 1997. This rate rose significantly to 61.2% in 2005. A significant decrease in the total 180-day readmission rate occurred from 18.95% in 1997 to 13.81% in 2005. These rates also significantly decreased for each surgical modality (from 16.30 to 11.38% for SB, from 21.29 to 14.69% for PPV, and from 22.99 to 16.55% for PPV+SB). The length of hospital stay decreased for each surgical modality between 1997 and 2005.
There was a significant trend towards more frequently employing primary PPV (with or without SB) for the management of primary RRD. In addition, significant improvements in the primary success rates were shown for each surgical modality group and for total samples between 1997 and 2005.
The Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) Trial cast doubt on the benefits of renal artery stenting (RAS). However, the outcomes for patients with chronic kidney disease ...(CKD) were not analyzed separately in the CORAL Trial. We hypothesized that patients who experienced a significant improvement in renal function after RAS would have improved long-term survival, compared with patients whose renal function was not improved by stenting.
This single-center retrospective study included 60 patients with stage 3 or worse CKD and renal artery occlusive disease who were treated with RAS for renal salvage. Patients were categorized as "responders" or "nonresponders" based on postoperative changes in estimated glomerular filtration rate (eGFR) after RAS. "Responders" were those patients with an improvement of at least 20% in eGFR over baseline; all others were categorized as "nonresponders." Survival was analyzed using the Kaplan-Meier method. Cox proportional hazards regression was used to identify predictors of long-term survival.
The median age of the cohort was 66 years (interquartile range IQR, 60-73). Median preoperative eGFR was 34 mL/min/1.73 m
(IQR, 24-45). At late follow-up (median 35 months, IQR, 22-97 months), 16 of 60 patients (26.7%) were categorized as "responders" with a median increase in postoperative eGFR of 40% (IQR, 21-67). Long-term survival was superior for responders, compared with nonresponders (P = 0.046 by log-rank test). Cox proportional hazards regression identified improved renal function after RAS as the only significant predictor of increased long-term survival (hazard ratio = 0.235, 95% confidence interval = 0.075-0.733; P = 0.0126 for improved versus worsened renal function after RAS).
Successful salvage of renal function by RAS is associated with improved long-term survival. These data provide an important counter argument to the prior negative clinical trials that found no benefit to RAS.
Global polarization of Ξ and Ω hyperons has been measured for the first time in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. The measurements of the $Ξ^{-}$ and $\overline{Ξ}^{+}$ hyperon ...polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay Ξ→Λ+π, as well as by measuring the polarization of the daughter Λ hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over $Ξ^{-}$ and $\overline{Ξ}^{+}$, is measured to be $\langle{P_{Ξ}}\rangle$=0.47±0.10(stat)±0.23(syst)% for the collision centrality 20%-80%. The $\langle{P_{Ξ}}\rangle$ is found to be slightly larger than the inclusive Λ polarization and in reasonable agreement with a multiphase transport model. The $\langle{P_{Ξ}}\rangle$ is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. Finally, the global polarization of Ω, $\langle{P_{Ω}}\rangle$=1.11±0.87(stat)±1.97(syst)% was obtained by measuring the polarization of daughter Λ in the decay Ω→Λ+K, assuming the polarization transfer factor $C_{ΩΛ}=1$.
Global polarization of Ξ and Ω hyperons has been measured for the first time in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. The measurements of the $Ξ^{-}$ and $\overline{Ξ}^{+}$ hyperon ...polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay Ξ→Λ+π, as well as by measuring the polarization of the daughter Λ hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over $Ξ^{-}$ and $\overline{Ξ}^{+}$, is measured to be $\langle{P_{Ξ}}\rangle$=0.47±0.10(stat)±0.23(syst)% for the collision centrality 20%-80%. The $\langle{P_{Ξ}}\rangle$ is found to be slightly larger than the inclusive Λ polarization and in reasonable agreement with a multiphase transport model. The $\langle{P_{Ξ}}\rangle$ is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. Finally, the global polarization of Ω, $\langle{P_{Ω}}\rangle$=1.11±0.87(stat)±1.97(syst)% was obtained by measuring the polarization of daughter Λ in the decay Ω→Λ+K, assuming the polarization transfer factor $C_{ΩΛ}=1$.
The present work proposes a novel numerical solution algorithm based on a differential quadrature (DQ) method to simulate natural convection in an inclined cubic cavity using velocity–vorticity form ...of the Navier–Stokes equations. Since the DQ method employs a higher-order polynomial to approximate any given differential operator, the vorticity values at the boundaries can be computed more accurately than the conventionally followed second-order accurate Taylor’s series expansion scheme. The numerical capability of the present algorithm is demonstrated by the application to natural convection in an inclined cubic cavity. The velocity Poisson equations, the continuity equation, the vorticity transport equations and the energy equation are all solved as a coupled system of equations for the seven field variables consisting of three velocities, three vorticities and temperature. Thus coupling the velocity and the vorticity transport equations allows the determination of the vorticity boundary values implicitly without requiring the explicit specification of the vorticity boundary conditions. The present algorithm is proved to be an efficient method to resolve the non-linearity involved with the vorticity transport equations and the energy equation. Test results obtained for an inclined cubic cavity with different angle of inclinations for Rayleigh number equal to 10
3, 10
4, 10
5 and 10
6 indicate that the present coupled solution algorithm could predict the benchmark results for temperature and flow fields using a much coarse computational grid compared to other numerical schemes.
PDF
