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( Ng Jonathan Patrick ),( Lau Lawrence Chun Man ),( Chau Wai-wang ),( Ong Michael Tim-yun ),( Cheung Kin Wing ),( Chiu Kwok Hing ),( Chung Kwong Yin ),( Ho Kevin Ki-wai ) 대한슬관절학회 2021 대한슬관절학회지 Vol.33 No.-
Background: The literature comparing the long-term outcomes and survivorship of computer navigation-assisted and conventional total knee replacement (TKR) is sparse. Moreover, of the available comparative studies with followup duration of more than 10 years, the results seem to be conflicting. The purpose of this long-term study was to compare the clinical and radiological outcomes, and implant survivorship, of TKR performed with and without computer navigation. Methods: We retrospectively compared the results of 49 computer-navigated TKRs and 139 conventional TKRs. The mean age of the patients was 67.9 (range 52-81) years for the navigation group and 67.1 (range 50-80) years for the conventional TKR group. The mean duration of follow-up for the conventional and navigation TKR groups was 12.9 and 13.2 years, respectively. Clinical and radiographic follow-up examinations of the patients were performed at 2 weeks, 1 month, 3 months and 6 months post-operatively, and at 1-year intervals thereafter. Results: There were no significant differences in the post-operative Knee Society knee and function score between the two groups. The mean overall deviation from neutral alignment and the radiological outliers were significantly higher in the conventional TKR group. The overall survival rates at 17 years were 92.9% for the navigation group and 95.6% for the conventional TKR group (p = 0.62). Conclusions: Navigated TKR resulted in fewer radiological outliers; however, this did not translate to better long-term functional outcomes or implant survival.
Cosmic birefringence fluctuations and cosmic microwave background <i>B</i>-mode polarization
Lee, Seokcheon,Liu, Guo-Chin,Ng, Kin-Wang Elsevier 2015 Physics letters: B Vol.746 No.-
<P><B>Abstract</B></P> <P>Recently, BICEP2 measurements of the cosmic microwave background (CMB) <I>B</I>-mode polarization has indicated the presence of primordial gravitational waves at degree angular scales, inferring the tensor-to-scalar ratio of r = 0.2 and a running scalar spectral index, provided that dust contamination is low. In this <I>Letter</I>, we show that the existence of the fluctuations of cosmological birefringence can give rise to CMB <I>B</I>-mode polarization that fits BICEP2 data with r < 0.11 and no running of the scalar spectral index. When dust contribution is taken into account, we derive an upper limit on the cosmological birefringence, A <SUP> β 2 </SUP> < 0.0075 , where <I>A</I> is the amplitude of birefringence fluctuations that couple to electromagnetism with a coupling strength <I>β</I>.</P>
Imprint of scalar dark energy on cosmic microwave background polarization
Lee, Seokcheon,Liu, Guo-Chin,Ng, Kin-Wang American Physical Society 2014 PHYSICAL REVIEW D - Vol.89 No.6
We study the imprint of a coupling of scalar dark energy to a photon on the cosmic microwave background polarization. Both the time-evolving field value and the perturbation of the scalar induce B-mode polarization. For a wide range of scalar dark energy models allowed by current observational data, we conclude that future cosmic microwave background data will find either a cosmic parity violation in a temperature-polarization correlation due to the field value, or perturbation-induced B-mode polarization that is indistinguishable from that generated by primordial gravitational waves.