Kinematic analysis of leg alignment during conventional versus navigated total knee arthroplasty: initial results of a prospective study.

Current kinematic navigation systems provide real-time spatial analyses of leg alignments during total knee arthroplasty (TKA) instead of delayed radiographic verification after surgery. A prospective study was conducted to investigate leg alignments of TKAs that underwent different surgical guidance [intramedullary (IM) jig-based vs. navigation-assisted] using a kinematic navigation system. Since May 2007, patients admitted for primary TKA were considered for inclusion. Within 6 months, 38 sets of intraoperative analyses on the operated legs have been performed. Excluding seven unreliable data sets, 15 conventional IM jig-based TKAs and 16 navigation-assisted TKAs were available. The leg alignments in maximum knee extension were retrieved for comparison. Although similar final coronal alignments were accurately achieved in both groups (0.21 valgus in the IM group vs. 0.17 valgus in the NA group, p=0.993), a more flexed sagittal axis was constructed with conventional IM jigs (1.93 flexion in the IM group vs. 0.58 extension in the NA group, p<0.05). The study suggests that comparable coronal precision could be achieved with conventional IM jigs by trained surgeons, although computer-assisted navigation is a documented method to restore accurate alignment. Different sagittal alignments observed in this study indicate the inherent discrepancy between different surgical guides as well as their according concepts.

Digitally synchronized LCD projector for multi-color fluorescence excitation in parallel capillary electrophoresis detection.

A simple method is proposed for modulating the excitation light used for multi-color fluorescence detection in a single capillary electrophoresis (CE) channel. In the proposed approach, a low-cost commercial liquid crystal device (LCD) projector with digitally-modulated LCD switches is used to provide the illumination light source and the fluorescence emitted from the CE chip is synchronously detected using an ultraviolet-visible-near infrared (UV-vis-NIR) spectrometer. The modulated light source enables the detection of multiple fluorescence signals within a single CE channel without the need of mechanically switching optical components. In order to enhance the sensing performance of the proposed system, two short-pass filters and one band-pass filter are inserted into the LCD projector to modify the wavelength spectra for fluorescence excitation. With this simple approach, the signal-to-noise (SN) ratio of the fluorescence detection signals is greatly improved by a factor of approximately 22 when detecting Atto647N fluorescent dye. The feasibility of the proposed multi-color CE detection approach is demonstrated by detecting two different samples including a mixed sample comprising FITC, Rhodamine B and Atto647N fluorescent dyes and a bio-sample composed of two ssDNAs labeled with FITC and Cy3, respectively. Results confirm that the digitally-modulated excitation system proposed in this study has significant potential for the parallel analysis of fluorescently-labeled bio-samples using a multi-color detection scheme.

Objective-type dark-field system applied to multi-wavelength capillary electrophoresis for fluorescent detection and analysis.

This paper presents an advanced diascopic illumination technique for simultaneous multi-wavelength fluorescence excitation and detection without using any spatial filter sets. The proposed system includes a home-built dark-field condenser comprising a high N.A. objective and a light stop-film to excite fluorescence and an ultraviolet-visible-near infrared (UV-VIS-NIR) spectrometer to detect emitted signals. Since no direct light source enters the optical detection system, no complex optical filter is required for multi-wavelength fluorescence detection. This study also designs an optimized stop-film pattern to obtain the best performance in exciting fluorescent samples and reduce background light. Experimental results show that the proposed system can effectively increase the fluorescent signal and simultaneously detect a mixed sample composed of 2',7'-dichlorofluorescein, Rhodamine B, Atto610, and Atto647N. Furthermore, this proposed system successfully separates and detects a mixed bio-sample composed of three single-stranded DNA samples labeled with Cy3, FITC, and Alexa647 fluorescence in a single channel. A simple and fast calculation removes noise and fluorescent cross-effect for conveniently observing the electropherograms. The proposed system has a measured detection limit up to 5x10(-8)M (S/N=3) while detecting a standard fluorescence of 2',7'-dichlorofluoresein, which is capable of detecting fluorescence samples in general applications. The proposed method provides a simple and straightforward way to detect multi-wavelength fluorescence for CE analysis.