[Comparative study of gap balancing and measured resection technique in patients receiving staged bilateral total knee arthroplasty].

Objective: To compare the clinical outcomes of staged total knee arthroplasty (TKA) performed on both knees in the same patient using gap balancing (GB) and measured resection (MR) techniques, respectively. Methods: The clinical data of 57 patients undergoing bilateral staged TKA at the Xi'an Jiaotong University Affiliated Honghui Hospital from July 2018 to January 2020 were analyzed. Using the random number table, MR or GB technique was selected when patients underwent primary TKA, and contralateral procedure was done with another technique. The procedures were performed by one chief surgeon, and the same prosthesis was chosen for all the procedures. The two osteotomy techniques for TKA were compared in terms of surgical status, radiographic data, functional recovery and satisfaction rate. Results: Total of 57 patients, including 16 males and 41 females, were included in the study with a mean age of (68.5±4.6) years (59-79 years) at primary TKA. All patients were followed up for (29.6±4.5) months (22-39 months). The interval between the two procedures was (4.7±3.0) months (0.5-12.0 months). Postoperative drainage was less in the GB side when compared with that in the MR side [(93.6±22.2) ml vs (109.9±36.9) ml, P=0.003]. At the 1-month postoperative follow-up, the visual analogue scale (VAS) of pain was lower on the GB side (3.0±0.8) than on the MR side (3.5±1.2), the range of motion (ROM) was higher on the GB side (105.7°±8.2° vs 100.2°±7.5°), the Knee Society Score (KSS) was higher on the GB side (78.5±5.4 vs 74.2±6.3), and the Western Ontario and McMaster University (WOMAC) score was lower on the GB side (35.4±5.5 vs 38.0±6.3), there were significant differences in the up-mentioned indexes between the two groups (all P<0.05). However, the repeated-measures analysis of variance indicated that there was no significant difference in VAS score, ROM, KSS score and WOMAC score between the two techniques (all P>0.05). The satisfactory rate of GB technique was 84.2%(48/57), ant it was 86.0%(49/57) with MR technique (P=0.446). There was also no significant difference between the two techniques in terms of complications (P=0.754). Conclusion: Both the GB and MR technique result in good knee function with similar clinical outcomes in patients receiving TKA in both knees for osteoarthritis without significant deformity.

Monolayer-graphene-based perfect absorption structures in the near infrared.

Subwavelength perfect optical absorption structures based on monolayer-graphene are analyzed and demonstrated experimentally. The perfect absorption mechanism is a result of critical coupling relating to a guided mode resonance of a low index two-dimensional periodic structure. Peak absorption over 99% at wavelength of 1526.5 nm with full-width at half maximum (FWHM) about 18 nm is demonstrated from a fabricated structure with period of 1230 nm, and the measured results agree well with the simulation results. In addition, the influence of geometrical parameters of the structure and the angular response for oblique incidence are analyzed in detail in the simulation. The demonstrated absorption structure in the presented work has great potential in the design of advanced photo-detectors and modulators.

Chip-integrated nearly perfect absorber at telecom wavelengths by graphene coupled with nanobeam cavity.

We exploit the concept of critical coupling to graphene based chip-integrated applications and numerically demonstrate that a chip-integrated nearly perfect graphene absorber at wavelengths around 1.55 µm can be obtained by graphene nearly critical coupling with a nanobeam cavity. The key points are reducing the radiation loss and transmission possibly, together with controlling the coupling rate of the cavity to the input waveguide to be equal to the absorption rate of the cavity caused by graphene. Simulation results show that the absorption of monolayer graphene with a total length of only a few microns is raised up to 97%. Our study may have potential applications in chip-integrated photodetectors.

Toward integrated electrically controllable directional coupling based on dielectric loaded graphene plasmonic waveguide.

We propose and numerically analyze a mid-infrared electrically controllable plasmonic waveguide directional coupler that is composed of two parallel identical straight dielectric loaded graphene plasmonic waveguide and S-shaped waveguide bends. By varying the Fermi energy level of the graphene sheet, the maximum power coupled from the input waveguide to the cross-waveguide and the corresponding coupling length could be effectively tuned. Under different Fermi energy level, this directional coupler could serve as an electrically controlled optical switch or a 3-dB splitter around the wavelength of 10.5 µm. Moreover, the size of the entire device is really in sub-wavelength scale making it very facilitative for high density integration.

Dielectric loaded graphene plasmon waveguide.

Dielectric loaded graphene plasmon waveguide (DLGPW) is proposed and investigated. An analytical model based on effective-index method is presented and verified by the finite element method simulations. The mode effective index, propagation loss, cutoff wavelength of higher order modes and single-mode operation region were derived at mid-infrared spectral region. By changing Fermi energy level, the propagation properties of fundamental mode could be tuned flexibly. The structure of the DLGPW is simple and easy for fabrication. It provided a new freedom to manipulate the graphene surface plasmons, which may led to new applications in actively tunable integrated optical devices.