Ultrabroad bandwidth of quasi-parametric amplification beyond the phase-matching limit.

Quasi-parametric amplification (QPA), a variant of optical parametric amplification, can release the phase-matching requirement owing to the introduction of idler dissipation, and thus may support ultrabroad bandwidth. Here we establish the gain-dispersion equation for QPA, which reveals the interplay of signal gain, idler dissipation and phase mismatch. The idler dissipation dramatically enhances the gain bandwidth, which breaks the limit set by phase matching. We theoretically demonstrate that QPA with strong dissipation allows high-efficiency few-cycle pulse amplification in those nonlinear crystals without a magic phase-matching solution.

Ultra-Confined Phonon Polaritons and Strongly Coupled Microcavity Exciton Polaritons in Monolayer MoSi2 N4 and WSi2 N4.

The 2D semiconductors are an ideal platform for exploration of bosonic fluids composed of coupled photons and collective excitations of atoms or excitons, primarily due to large excitonic binding energies and strong light-matter interaction. Based on first-principles calculations, it is demonstrated that the phonon polaritons formed by two infrared-active phonon modes in monolayer MoSi2 N4 and WSi2 N4 possess ultra-high confinement factors of around ≈105 and 103 , surpassing those of conventional polaritonic thin-film materials by two orders of magnitude. It is observed that the first bright exciton possesses a substantial binding energies of 750 and 740 meV in these two monolayers, with the radiative recombination lifetimes as long as 25 and 188 ns, and the Rabi splitting of the formed cavity-exciton polaritons reaching 373 and 321 meV, respectively. The effective masses of the cavity exciton polaritons are approximately 10-5 me , providing the potential for high-temperature quantum condensation. The ultra-confined and ultra-low-loss phonon polaritons, as well as strongly-coupled cavity exciton polaritons with ultra-small polaritonic effective masses in these two monolayers, offering the flexible control of light at the nanoscale, probably leading to practical applications in nanophotonics, meta-optics, and quantum materials.

Structure and function of the Arabidopsis ABC transporter ABCB19 in brassinosteroid export.

Brassinosteroids are steroidal phytohormones that regulate plant development and physiology, including adaptation to environmental stresses. Brassinosteroids are synthesized in the cell interior but bind receptors at the cell surface, necessitating a yet to be identified export mechanism. Here, we show that a member of the ATP-binding cassette (ABC) transporter superfamily, ABCB19, functions as a brassinosteroid exporter. We present its structure in both the substrate-unbound and the brassinosteroid-bound states. Bioactive brassinosteroids are potent activators of ABCB19 ATP hydrolysis activity, and transport assays showed that ABCB19 transports brassinosteroids. In Arabidopsis thaliana, ABCB19 and its close homolog, ABCB1, positively regulate brassinosteroid responses. Our results uncover an elusive export mechanism for bioactive brassinosteroids that is tightly coordinated with brassinosteroid signaling.

Strong Intervalley Scattering-Induced Renormalization of Electronic and Thermal Transport Properties and Selection Rule Analysis in 2D Tellurium.

The electron-phonon interaction (EPI) and phonon-phonon interactions are ubiquitous in promising two-dimensional (2D) semiconductors, determining both electronic and thermal transport properties. In this work, based on ab initio calculations, the effects of intervalley scattering on EPI and higher-order four-phonon interactions of α-Te and ß-Te are investigated. Through the proposed selection rules for scattering channels and calculations of full electron-phonon scattering rates, we demonstrate that multiple nearly degenerate local valleys/peaks produce more scattering channels, resulting in stronger intervalley scattering over intravalley scattering. The lattice thermal conductivities of α-Te and ß-Te are decreased by as much as 10.9% and 30.8% by considering EPI under the carrier concentration of 2 × 1013 cm-2 (n-type) at 300 K compared to those limited by three-phonon scattering, respectively. However, when further considering four-phonon scattering, EPI reduces the lattice thermal conductivities by 2.6% and 19.4% for α-Te and ß-Te, respectively. Furthermore, it is revealed that the four-phonon interaction is more dominant in phonon transport for α-Te than that for ß-Te due to the presence of an acoustic-optical phonon gap in α-Te. Finally, we demonstrate strong intervalley scattering induces significant renormalization effects from EPI on all the constituent parameters of thermoelectric performance. Our results show the contributions of intervalley scattering to the electronic properties as well as thermal transport properties in band-convergent thermoelectric materials are essential and highlight the potential of monolayer tellurium as a promising candidate for advanced thermoelectric applications.

A bibliometric and visualized analysis of meniscus suture based on the WOS core collection from 2010 to 2022: A review.

Meniscus suture is an important treatment method for meniscus injury and contributes to the preservation of proprioception, restoration of knee biomechanics and alleviation of progressive osteoarthritis. However, there are few visualized analyses concerning the present studies of meniscus suture. This paper aims to evaluate the global trends, highlights and frontiers of meniscus suture. A bibliometric analysis was conducted based on the results of studies related to meniscus suture from web of science core collection. VOSviewer, GraphPad Prism, Microsoft Excel and R-bibliometrix were utilized for the bibliometric analysis of country and institution distribution, chronological distribution, source journals analysis, prolific authors and institutions analysis, keywords analysis, and reference co-citation analysis. A total of 950 publications on meniscus suture from 177 different sources were retrieved over the set time span. These publications were completed by 3177 authors from 1112 institutions in 54 countries. The United States was the most prolific country with 7960 citations and 348 publications (36.63%). Furumatsu Takayuki acted as the most prolific author (51 publications), while Robert F LaPrade with 1398 citations was the most-cited author. And more papers were published in the core journals, including American Journal of Sports Medicine, Arthroscopy-The Journal of Arthroscopic and Related Surgery, Knee Surgery Sports Traumatology Arthroscopy and Arthroscopy Techniques. Furthermore, "meniscus healing," "meniscus root tear" seem to be the emerging research hotspots. Notably, the publication trend concerning the all-inside suture technique has been rising during the past decade. The number of research publications on meniscus suture has been continuously risen since 2010. The authors, publications and institutions from the United States and East Asia were still the mainstays in this field. And the all-inside suture may become the mainstream surgical technique in the future, with meniscus healing and meniscus root tears being research highlights recently.

Trends and hotspots of publications on ferroptosis: A 10 Year overview.

Background: Ferroptosis was proposed to be a type of programmed cell death in 2012. Ferroptosis plays a significant role in a variety of illnesses. Objective: To better understand the direction of future research, we performed a bibliometric analysis to identify research hotspots with a focus on ferroptosis. Methods: The search terms [TI = "ferroptosis" OR ("GSH" AND "GPX4") OR "lipid peroxidation" OR "iron homeostasis" OR "iron metabolism"] AND [PY = "2012-2022"] AND [DT = "Article OR Review"] AND [LA = "English"] were used to retrieve publications related to ferroptosis for a bibliometric analysis. We utilized Microsoft Excel to calculate the frequency and proportion of the published articles, VOSviewer to perform a co-occurrence analysis and for visualizing the data, CiteSpace to obtain a timeline of keywords and institutions, and RStudio to calculate citation metrics. As indicated by the analysis, indicators such as the number of publications, the most productive authors and coauthorship status, the distribution of publications by country, favoured journals, the most influential institutions and the most frequently cited documents are reported in this article. Results: A total of 8009 publications were retrieved from the WOS core collection, and 197 papers published in 2023 were removed from this analysis. The remaining 7812 papers, which included 118 in the WOS collection, were incorporated into the bibliometric study. Conclusion: The number of annual scientific publications on ferroptosis have been increasing each year. The academic communities represented by Tang, Daolin, Stockwell, Brent R., Wang, Fudi, and Conrad, Marcus were the most authoritative. China, USA, and Germany were the front-runners in the field of ferroptosis. Free Radical Biology and Medicine was the largest contributor of ferroptosis-related research, and Cell and Nature were the most influential journals to publish articles on ferroptosis. Columbia Univ and Univ Pittsburgh were the institutions that received the most attention. Recent research on ferroptosis has been focused on molecular mechanisms, particularly those in the contexts of various diseases, which will be a hotspot of future research. In addition, interdisciplinary ferroptosis and big-data research is expected to be a new frontier.

Widely-tunable all-fiber Tm doped MOPA with > 1†kW of output power.

In this paper, we report on a high-power and widely tunable thulium-doped fiber laser (TDFL) based on a monolithic master oscillator power amplifier (MOPA) system. The master oscillator is a Tm fiber ring laser incorporating a tunable bandpass filter to realize narrow linewidth and wavelength tunable operation. The MOPA generated 1010 W ∼1039 W of output power over a tuning range of 107 nm from 1943 to 2050nm with slope efficiencies of more than 51% and spectra linewidth of ∼0.5 nm. Power stability (RMS) in ∼10 min scale is measured to be ∼0.52%. A diffraction-limited beam quality factor M2 of ∼1.18 is measured at 920 W of laser output. Output power is pump-limited without the onset of parasitic oscillation or amplified spontaneous emission (ASE) even at the maximum power level. This is the first demonstration, to the best of our knowledge, on an all-fiber integrated wavelength-tunable TDFL at 2 µm with output power exceeding 1 kW.

High power Ho:Y2O3 ceramic laser with controllable output intensity profile at 2.1 µm.

We report on a high-power Ho:Y2O3 ceramic laser at 2.1 µm with controllable output beam profile ranging from LG01 donut, flat-top to TEM00 mode using a simple two-mirror resonator. In-band pumped at 1943nm using a Tm fiber laser beam shaped via a coupling optics comprising a capillary fiber and lens-combination to achieve distributed pump absorption in Ho:Y2O3 and hence selective excitation of the target mode, the laser yields 29.7 W of LG01 donut, 28.0 W of crater-like, 27.7 W of flat-top and 33.5 W of TEM00 mode output for absorbed pump power of 53.5 W, 56.2 W, 57.3 W and 58.2 W, respectively, corresponding to a slope efficiency of 58.5%, 54.3%, 53.8% and 61.2%. This is, to the best of our knowledge, the first demonstration of laser generation with continuously tunable output intensity profile at ∼2 µm wavelength region.

P-type nitrogen-doped ß-Ga2O3: the role of stable shallow acceptor NO-VGa complexes.

In-depth understanding of the acceptor states and origins of p-type conductivity is essential and critical to overcome the great challenge for the p-type doping of ultrawide-bandgap oxide semiconductors. In this study we find that stable NO-VGa complexes can be formed with ε(0/-) transition levels significantly smaller than those of the isolated NO and VGa defects using N2 as the dopant source. Due to the defect-induced crystal-field splitting of the p orbitals of Ga, O and N atoms, and the Coulomb binding between NO(II) and VGa(I), an a' doublet state at 1.43 eV and an a'' singlet state at 0.22 eV above the valence band maximum (VBM) are formed for the ß-Ga2O3:NO(II)-VGa(I) complexes with an activated hole concentration of 8.5 × 1017 cm-3 at the VBM, indicating the formation of a shallow acceptor level and the feasibility to obtain p-type conductivity in ß-Ga2O3 even when using N2 as the dopant source. Considering the transition from NO(II)-V0Ga(I) + e to NO(II)-V-Ga(I), an emission peak at 385 nm with a Franck-Condon shift of 1.08 eV is predicted. These findings are of general scientific significance as well as technological application significance for p-type doping of ultrawide-bandgap oxide semiconductors.

Spin-Orbit-Coupling-Induced Topological Transition and Anomalously Strong Intervalley Scattering in Two-Dimensional Bismuth Allotropes with Enhanced Thermoelectric Performances.

The convergence of multivalley bands is originally believed to be beneficial for thermoelectric performance by enhancing the charge conductivity while preserving the Seebeck coefficients, based on the assumption that electron interband or intervalley scattering effects are totally negligible. In this work, we demonstrate that ß-Bi with a buckled honeycomb structure experiences a topological transition from a normal insulator to a Z2 topological insulator induced by spin-orbit coupling, which subsequently increases the band degeneracy and is probably beneficial for enhancement of the thermoelectric power factor for holes. Therefore, strong intervalley scattering can be observed in both band-convergent ß- and aw-Bi monolayers. Compared to ß-Bi, aw-Bi with a puckered black-phosphorus-like structure possesses high carrier mobilities with 318 cm2/(V s) for electrons and 568 cm2/(V s) for holes at room temperature. We also unveil extraordinarily strong fourth phonon-phonon interactions in these bismuth monolayers, significantly reducing their lattice thermal conductivities at room temperature, which is generally anomalous in conventional semiconductors. Finally, a high thermoelectric figure of merit (zT) can be achieved in both bismuth monolayers, especially for aw-Bi with an n-type zT value of 2.2 at room temperature. Our results suggest that strong fourth phonon-phonon interactions are crucial to a high thermoelectric performance in these materials, and two-dimensional bismuth is probably a promising thermoelectric material due to its enhanced band convergence induced by the topological transition.

High power and efficient operation of a Ho:Y2O3 ceramic laser with over 210 W of output power at 2.1 µm.

We report on power scaling and efficient operation of a Ho:Y2O3 ceramic laser at 2.1 µm in-band pumped with an incoherently beam combined high power and narrow-linewidth Tm fiber source at 1931.2 nm. The 0.5 at.% Ho3+ doped Ho:Y2O3 ceramic is fabricated in-house with scattering loss of < 0.25% cm-1. Up to 210.5 W of continuous-wave output power has been generated at 2117 nm for 366 W absorbed pump power shaped with a one-dimensional top-hat profile, corresponding to a slope efficiency of 60.0% with respect to the absorbed pump power. A slope efficiency of 67.5% has been demonstrated with 160 W of output power using a circular beam pump configuration. Results presented in this work verify the superior power scaling capability of a Ho:Y2O3 ceramic laser with high efficiency at ∼2.1 µm.

Finite-momentum excitons and the role of electron-phonon couplings in the electronic and phonon transport properties of boron arsenide.

The emerging semiconductor boron arsenide (BAs) with high thermal conductivity has attracted much attention recently, due to its promising application to overcome the bottleneck of high-density heat generated in power electronics and optoelectronic devices. In this work, based on first-principles calculations, we find that cubic BAs possesses high intrinsic electron/hole mobilities and the ionized impurity scattering plays a more important role in carrier scattering, compared with other scattering processes. The mobilities can be significantly enhanced by 14.9% and 76.2% for electrons and holes, respectively, by strain engineering. The investigation of the optoelectronic properties of indirect semiconductor cubic BAs by considering the many-body excitonic effects reveals that the contribution from finite-momentum excitons to optical properties is larger for photon energy ranging from 2.25 eV to 3.50 eV, compared with that from zero-momentum excitons. Finally, we observe that the phonon-electron couplings to total lattice thermal conductivities are non-trivial at low temperatures. These findings provide new insight into the transport and optoelectronic properties of cubic BAs, which are beneficial for the acceleration of the application of this revolutionary thermal management material.

Discovery of Lead-Free Perovskites for High-Performance Solar Cells via Machine Learning: Ultrabroadband Absorption, Low Radiative Combination, and Enhanced Thermal Conductivities.

Exploring lead-free candidates and improving efficiency and stability remain the obstacle of hybrid organic-inorganic perovskite-based devices commercialization. Traditional trial-and-error methods seriously restrict the discovery especially for large search space, complex crystal structure and multi-objective properties. Here, the authors propose a multi-step and multi-stage screening scheme to accelerate the discovery of hybrid organic-inorganic perovskites A2 BB'X6 from a large number of candidates through combining machine learning with high-throughput calculations for pursuing excellent efficiency and thermal stability in solar cells. Followed by a series of screenings, the structure-property relationships mapping A2 BB'X6 properties are built and the predictions are close to reported experimental results. Successfully, four experimental-feasibly candidates with good stability, high Debye temperature and suitable band gap are screened out and further verified by density-functional theory calculations, in which the predicted efficiency for three lead-free candidates ((CH3 NH3 )2 AgGaBr6 , (CH3 NH3 )2 AgInBr6 and (C2 NH6 )2 AgInBr6 ) achieves 20.6%, 19.9% and 27.6% due to ultrabroadband absorption region ranging from UVC to IRC with excitonic radiative combination rates as low as 10 ps, large or intermediate polarons form with properties similar to CH3 NH3 PbI3 and the calculated thermal conductivities are 5.04, 4.39 and 5.16 Wm-1 K-1 , respectively, with Debye temperatures larger than 500 K, beneficial for suppression of both nonradiative combination and heat-induced degradation.

Thermoelectric performance of 2D materials: the band-convergence strategy and strong intervalley scatterings.

The strategy of band convergence of multi-valley conduction bands or multi-peak valence bands has been widely used to search or improve thermoelectric materials. However, the phonon-assisted intervalley scatterings due to multiple band degeneracy are usually neglected in the thermoelectric community. In this work, we investigate the (thermo)electric properties of non-polar monolayer ß- and α-antimonene considering full mode- and momentum-resolved electron-phonon interactions. We also analyze thoroughly the selection rules on electron-phonon matrix-elements using group-theory arguments. Our calculations reveal strong intervalley scatterings between the nearly degenerate valley states in both ß- and α-antimonene, and the commonly-used deformation potential approximation neglecting the dominant intervalley scattering gives inaccurate estimations of the electron-phonon scattering and thermoelectric transport properties. By considering full electron-phonon interactions based on the rigid-band approximation, we find that, the maximum value of the thermoelectric figure of merits zT at room temperature reduces to 0.37 in ß-antimonene, by a factor of 5.7 compared to the value predicted based on the constant relaxation-time approximation method. Our work not only provides an accurate prediction of the thermoelectric performances of antimonenes, which reveals the key role of intervalley scatterings in determining the electronic part of zT, but also exhibits a computational framework for thermoelectric materials.

High-power cylindrical vector beams generated from an all-fiber linearly polarized laser by metasurface extracavity conversion.

Five-hundred-watt cylindrical vector beams (CVBs) at 1030 nm with the 3 dB linewidth being less than 0.25 nm have been generated from a narrow linewidth all-fiber linearly polarized laser by metasurface extracavity conversion. At maximum output power, the transmission efficiency and polarization extinction ratio of radially polarized cylindrical vector beams (RP-CVBs) are beyond 98% and 95%, respectively. The average power is approximately an order higher than previously reported high-power narrow-linewidth CVBs generated from fiber lasers. The temperature rise of the metasurface is less than 10°C at 500 W output power, which means that the system can be further power-scaled in the near future. The high-power, high-purity, and high-efficiency RP-CVBs generated by the metasurface demonstrate potential application of a metasurface in high-power CVBs lasers.

CsCDPK6, a CsSAMS1-Interacting Protein, Affects Polyamine/Ethylene Biosynthesis in Cucumber and Enhances Salt Tolerance by Overexpression in Tobacco.

S-adenosylmethionine synthetase (SAMS) plays a crucial role in regulating stress responses. In a recent study, we found that overexpression of the cucumber gene CsSAMS1 in tobacco can affect the production of polyamines and ethylene, as well as enhancing the salt stress tolerance of tobacco, but the exact underlying mechanisms are elusive. The calcium-dependent protein kinase (CDPK) family is ubiquitous in plants and performs different biological functions in plant development and response to abiotic stress. We used a yeast two-hybrid system to detect whether the protein CDPK6 could interact with SAMS1 and verified their interaction by bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP) assays. To further explore the function of cucumber CDPK6, we isolated and characterized CsCDPK6 in cucumber. CsCDPK6 is a membrane protein that is highly expressed under various abiotic stresses, including salt stress. It was also observed that ectopic overexpression of CsCDPK6 in tobacco enhanced salt tolerance. Under salt stress, CsCDPK6-overexpressing lines enhanced the survival rate and reduced stomatal apertures in comparison to wild-type (WT) lines, as well as lowering malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents and causing less relative electrolyte leakage. Moreover, repression of CsCDPK6 expression by virus-induced gene silencing (VIGS) in cucumber seedling cotyledons under salt stress increased ethylene production and promoted the transformation from putrescine (Put) to spermidine (Spd) and spermine (Spm). These findings shed light on the interaction of CsSAMS1 and CsCDPK6, which functions positively to regulate salt stress in plants.

Calculation of Transport Parameters Using ab initio and AMOEBA Polarizable Force Field Methods.

The transport properties of chemical species such as coefficients of diffusion, thermal conductivity, and viscosity have been widely used in combustion modeling. Lennard-Jones parameters fitted from the accurate intermolecular potential energy surfaces are crucial to obtain such information. Hence, a fast and accurate energy function is always desired for this purpose. In this study, the quality of a widely used polarizable force field AMOEBA was examined for the interaction between noble gases and n-alkanes. First, the intermolecular energy was compared between AMOEBA, MP2/CBS, MP2/aug'-cc-pVDZ, and QCISD(T)/CBS. The root mean squared error of the original AMOEBA was 10.31 cm-1 against QCISD(T)/CBS for all conformations. This was comparable with the errors of 10.84 and 7.75 cm-1 for MP2/aug'-cc-pVDZ and MP2/CBS, respectively. Further optimizing the van der Waals parameters of noble gases, the error of the force field against QCISD(T)/CBS was reduced to 6.24 cm-1, even better than the MP2/CBS results. Based on the optimized force field parameters, the intermolecular Lennard-Jones parameters were derived using the spherically averaged method and one-dimensional minimization method for a set of (n-alkanes, noble gases) pairs. The discrepancy of the one-dimensional minimization predicted Lennard-Jones collision rates from the tabulated values was typically within 10%, while it could be as large as 20-30% for the spherically averaged method. Additionally, the binary diffusion coefficients were calculated using the present Lennard-Jones parameters. In this case, the parameters derived from the spherically averaged method perform better. The mean unsigned error of the diffusion coefficients is usually within 5%, which is in good agreement with the experimental results. The results demonstrate that the AMOEBA force field can be used to generate the transport parameters systematically.

Experimental investigation of quasi-static mode degradation in a high power large mode area fiber amplifier.

In this work, quasi-static mode degradation in high power fiber amplifiers has been investigated experimentally. An increase of M2 from 1.3 to 2.6 with distortion of the beam profile is observed, which results in the signal spectra and backward light characterization departing from the traditional phenomena. The amplifier has been operated at the same input pump power of 705 W for nearly 2.2 hours to investigate the relationship between quasi-static mode degradation and photodarkening. The evolution of M2 factor/beam profile, mode correlation coefficient and output laser power at different working times indicate that the quasi-static mode degradation in the high power fiber amplifiers is dependent on photodarkening and evolves on the scale of tens of minutes. A visible green light has been injected to photobleach the gain fiber for 19 hours, which reveals that the quasi-static mode degradation has been suppressed simultaneously. To the best of our knowledge, this is the first detail report of photodarkening-induced quasi-static degradation in high power fiber amplifiers.

Timing to achieve the best recurrence-free survival after neoadjuvant chemoradiotherapy in locally advanced rectal cancer: experience in a large-volume center in China.

AIM: To identify the optimal interval from the end of neoadjuvant chemoradiotherapy to surgery (CRT-surgery interval) based on long-term oncological outcome of locally advanced rectal cancer (LARC). METHODS: Retrospective data analysis is reported from patients diagnosed with cT3 or T4 or TxN+ rectal cancer who underwent neoadjuvant treatment and curative-intent surgery between January 2010 and December 2018. With a priority focus on the effect of interval on oncological prognosis, we used recurrence-free survival (RFS) as the primary endpoint to determine the best cutoff point of time intervals. Then, the short-term and long-term outcomes of patients from longer and shorter interval groups were compared. RESULTS: Data from 910 patients were analyzed, with 185 patients who achieved pCR (20.3%). The trend for increased rates of pCR for groups with a prolonged time interval was not observed (P = 0.808). X-tile determined a cutoff value of 10.5 weeks, and the population was divided into longer (> 10 weeks) and shorter (≤ 10 weeks) interval groups. The shorter interval was associated with a higher wound infection rate (4.7% vs. 1.1%, P = 0.031), but other postoperative complications did not differ between the groups. The 5-year RFS rate was significantly higher in patients in a longer group than those in the shorter weeks group (86.8% vs. 77.8%, P = 0.016). The 5-year OS rates between groups were similar (84.1% vs. 82.5%, P = 0.257). Local recurrence and lung metastases rates were higher in shorter interval group than those of longer group (local recurrence rate: 1.7% vs. 5.1%, P = 0.049; lung metastases rate: 5.7% vs. 10.7%, P = 0.047). Cox multivariate regression analysis confirmed the CRT-surgery interval (HR = 0.599, P = 0.045) to be an independent prognostic factor of RFS. CONCLUSION: This study is the first, to the best of our knowledge, to define the optimal CRT-surgery interval based on RFS as the primary endpoint. Prolonging the waiting period to 10 weeks after the completion of CRT with additional chemotherapy cycles during the interval period might be a promising option to improve oncological survival in LARC patients treated with CRT and TME without compromising the surgical safety. Further randomized controlled trials investigating this are warranted to prove a clearly causality.

Remnant-Preserving Posterior Cruciate Ligament Reconstruction Over Remnant Fibers Using a Figure-of-Four Position and a Posterior Trans-Septal Portal.

Anatomic tunnel formation and remnant preservation are the recent trends in posterior cruciate ligament (PCL) reconstruction. However, it is difficult to observe the anatomical PCL footprint and perform the operation in the process of remnant-preserving PCL reconstruction. This study describes a single-bundle, transtibial PCL reconstruction technique with anatomic graft passage over the remnant PCL fibers. A femoral tunnel of PCL is created at 2 mm medial to the roof of the intercondylar notch and 3 mm proximal to the margin of the articular cartilage. The tibial insertion of PCL is observed using a figure-of-four position through a posterior trans-septal portal. A tibial bone tunnel is made below the distal center portion of the tibial insertion of residual PCL fibers. The graft is passed over the PCL through the tibial bone tunnel, the space between the anterior cruciate ligament (ACL) and the residual PCL fibers, to the femoral socket and is fixed by the EndoButton and screw. This technique is able to ensure a reasonable intra-articular length and optimal isometry. It has been applied in patients with PCL rupture and posterior instability of the knee joint, and no intraoperative or postoperative complications occurred. Our technology provides a valuable new treatment option for PCL rupture. Future comparative studies are needed to further clarify its beneficial effect.