All-optical physiology resolves a synaptic basis for behavioral timescale plasticity.

Learning has been associated with modifications of synaptic and circuit properties, but the precise changes storing information in mammals have remained largely unclear. We combined genetically targeted voltage imaging with targeted optogenetic activation and silencing of pre- and post-synaptic neurons to study the mechanisms underlying hippocampal behavioral timescale plasticity. In mice navigating a virtual-reality environment, targeted optogenetic activation of individual CA1 cells at specific places induced stable representations of these places in the targeted cells. Optical elicitation, recording, and modulation of synaptic transmission in behaving mice revealed that activity in presynaptic CA2/3 cells was required for the induction of plasticity in CA1 and, furthermore, that during induction of these place fields in single CA1 cells, synaptic input from CA2/3 onto these same cells was potentiated. These results reveal synaptic implementation of hippocampal behavioral timescale plasticity and define a methodology to resolve synaptic plasticity during learning and memory in behaving mammals.

Structural basis for ion selectivity in potassium-selective channelrhodopsins.

KCR channelrhodopsins (K+-selective light-gated ion channels) have received attention as potential inhibitory optogenetic tools but more broadly pose a fundamental mystery regarding how their K+ selectivity is achieved. Here, we present 2.5-2.7 Å cryo-electron microscopy structures of HcKCR1 and HcKCR2 and of a structure-guided mutant with enhanced K+ selectivity. Structural, electrophysiological, computational, spectroscopic, and biochemical analyses reveal a distinctive mechanism for K+ selectivity; rather than forming the symmetrical filter of canonical K+ channels achieving both selectivity and dehydration, instead, three extracellular-vestibule residues within each monomer form a flexible asymmetric selectivity gate, while a distinct dehydration pathway extends intracellularly. Structural comparisons reveal a retinal-binding pocket that induces retinal rotation (accounting for HcKCR1/HcKCR2 spectral differences), and design of corresponding KCR variants with increased K+ selectivity (KALI-1/KALI-2) provides key advantages for optogenetic inhibition in vitro and in vivo. Thus, discovery of a mechanism for ion-channel K+ selectivity also provides a framework for next-generation optogenetics.

Structural basis for channel conduction in the pump-like channelrhodopsin ChRmine.

ChRmine, a recently discovered pump-like cation-conducting channelrhodopsin, exhibits puzzling properties (large photocurrents, red-shifted spectrum, and extreme light sensitivity) that have created new opportunities in optogenetics. ChRmine and its homologs function as ion channels but, by primary sequence, more closely resemble ion pump rhodopsins; mechanisms for passive channel conduction in this family have remained mysterious. Here, we present the 2.0 Å resolution cryo-EM structure of ChRmine, revealing architectural features atypical for channelrhodopsins: trimeric assembly, a short transmembrane-helix 3, a twisting extracellular-loop 1, large vestibules within the monomer, and an opening at the trimer interface. We applied this structure to design three proteins (rsChRmine and hsChRmine, conferring further red-shifted and high-speed properties, respectively, and frChRmine, combining faster and more red-shifted performance) suitable for fundamental neuroscience opportunities. These results illuminate the conduction and gating of pump-like channelrhodopsins and point the way toward further structure-guided creation of channelrhodopsins for applications across biology.

Cardiogenic control of affective behavioural state.

Emotional states influence bodily physiology, as exemplified in the top-down process by which anxiety causes faster beating of the heart1-3. However, whether an increased heart rate might itself induce anxiety or fear responses is unclear3-8. Physiological theories of emotion, proposed over a century ago, have considered that in general, there could be an important and even dominant flow of information from the body to the brain9. Here, to formally test this idea, we developed a noninvasive optogenetic pacemaker for precise, cell-type-specific control of cardiac rhythms of up to 900 beats per minute in freely moving mice, enabled by a wearable micro-LED harness and the systemic viral delivery of a potent pump-like channelrhodopsin. We found that optically evoked tachycardia potently enhanced anxiety-like behaviour, but crucially only in risky contexts, indicating that both central (brain) and peripheral (body) processes may be involved in the development of emotional states. To identify potential mechanisms, we used whole-brain activity screening and electrophysiology to find brain regions that were activated by imposed cardiac rhythms. We identified the posterior insular cortex as a potential mediator of bottom-up cardiac interoceptive processing, and found that optogenetic inhibition of this brain region attenuated the anxiety-like behaviour that was induced by optical cardiac pacing. Together, these findings reveal that cells of both the body and the brain must be considered together to understand the origins of emotional or affective states. More broadly, our results define a generalizable approach for noninvasive, temporally precise functional investigations of joint organism-wide interactions among targeted cells during behaviour.

Glioma synapses recruit mechanisms of adaptive plasticity.

The role of the nervous system in the regulation of cancer is increasingly appreciated. In gliomas, neuronal activity drives tumour progression through paracrine signalling factors such as neuroligin-3 and brain-derived neurotrophic factor1-3 (BDNF), and also through electrophysiologically functional neuron-to-glioma synapses mediated by AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors4,5. The consequent glioma cell membrane depolarization drives tumour proliferation4,6. In the healthy brain, activity-regulated secretion of BDNF promotes adaptive plasticity of synaptic connectivity7,8 and strength9-15. Here we show that malignant synapses exhibit similar plasticity regulated by BDNF. Signalling through the receptor tropomyosin-related kinase B16 (TrkB) to CAMKII, BDNF promotes AMPA receptor trafficking to the glioma cell membrane, resulting in increased amplitude of glutamate-evoked currents in the malignant cells. Linking plasticity of glioma synaptic strength to tumour growth, graded optogenetic control of glioma membrane potential demonstrates that greater depolarizing current amplitude promotes increased glioma proliferation. This potentiation of malignant synaptic strength shares mechanistic features with synaptic plasticity17-22 that contributes to memory and learning in the healthy brain23-26. BDNF-TrkB signalling also regulates the number of neuron-to-glioma synapses. Abrogation of activity-regulated BDNF secretion from the brain microenvironment or loss of glioma TrkB expression robustly inhibits tumour progression. Blocking TrkB genetically or pharmacologically abrogates these effects of BDNF on glioma synapses and substantially prolongs survival in xenograft models of paediatric glioblastoma and diffuse intrinsic pontine glioma. Together, these findings indicate that BDNF-TrkB signalling promotes malignant synaptic plasticity and augments tumour progression.

Crystal structure of the natural anion-conducting channelrhodopsin GtACR1.

The naturally occurring channelrhodopsin variant anion channelrhodopsin-1 (ACR1), discovered in the cryptophyte algae Guillardia theta, exhibits large light-gated anion conductance and high anion selectivity when expressed in heterologous settings, properties that support its use as an optogenetic tool to inhibit neuronal firing with light. However, molecular insight into ACR1 is lacking owing to the absence of structural information underlying light-gated anion conductance. Here we present the crystal structure of G. theta ACR1 at 2.9 Å resolution. The structure reveals unusual architectural features that span the extracellular domain, retinal-binding pocket, Schiff-base region, and anion-conduction pathway. Together with electrophysiological and spectroscopic analyses, these findings reveal the fundamental molecular basis of naturally occurring light-gated anion conductance, and provide a framework for designing the next generation of optogenetic tools.

Structural mechanisms of selectivity and gating in anion channelrhodopsins.

Both designed and natural anion-conducting channelrhodopsins (dACRs and nACRs, respectively) have been widely applied in optogenetics (enabling selective inhibition of target-cell activity during animal behaviour studies), but each class exhibits performance limitations, underscoring trade-offs in channel structure-function relationships. Therefore, molecular and structural insights into dACRs and nACRs will be critical not only for understanding the fundamental mechanisms of these light-gated anion channels, but also to create next-generation optogenetic tools. Here we report crystal structures of the dACR iC++, along with spectroscopic, electrophysiological and computational analyses that provide unexpected insights into pH dependence, substrate recognition, channel gating and ion selectivity of both dACRs and nACRs. These results enabled us to create an anion-conducting channelrhodopsin integrating the key features of large photocurrent and fast kinetics alongside exclusive anion selectivity.

The efficacy of intraarticular viscosupplementation after arthroscopic partial meniscectomy: a randomized controlled trial.

BACKGROUND: This study aimed to evaluate the efficacy of viscosupplementation after arthroscopic partial meniscectomy. METHOD: A randomized controlled trial of 47 patients who underwent arthroscopic partial meniscectomy was conducted between March 2020 and March 2021. Patients were randomized into two groups: a viscosupplementation group (n = 23) and a control group (n = 24). A single-dose intraarticular hyaluronic acid injection was used as viscosupplementation. The 100 mm visual analogue scale (VAS) for pain assessment was measured at baseline and at 1 day, 2 weeks, 6 weeks, and 3 months post-surgery. The International Knee Documentation Committee (IKDC), Tegner, Lysholm, and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores and range of motion (ROM) of the knee were measured at baseline, 2 weeks, 6 weeks, and 3 months. RESULTS: The 100 mm VAS score for pain was significantly lower in the viscosupplementation group at 2 weeks post-surgery (27.5 mm vs. 40.7 mm, P = 0.047). ROM was significantly greater in the viscosupplementation group than in the control group at 2 weeks (131.5° vs. 121.0°, P = 0.044) post-surgery. No significant differences were observed in the IKDC or in the Tegner, Lysholm, and WOMAC scores between the two groups. CONCLUSIONS: Viscosupplementation after arthroscopic partial meniscectomy significantly reduced pain at 2 weeks post-surgery and improved ROM of the knee at 2 weeks post-surgery. There might be some benefits in terms of pain and functional recovery of viscosupplementation after arthroscopic surgery. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. TRIAL REGISTRATION: This randomized controlled trial was registered at cris.nih.go.kr # KCT0004921 .

Polarization Control of Deterministic Single-Photon Emitters in Monolayer WSe2.

Single-photon emitters, the basic building blocks of quantum communication and information, have been developed using atomically thin transition metal dichalcogenides (TMDCs). Although the bandgap of TMDCs was spatially engineered in artificially created defects for single-photon emitters, it remains a challenge to precisely align the emitter's dipole moment to optical cavities for the Purcell enhancement. Here, we demonstrate position- and polarization-controlled single-photon emitters in monolayer WSe2. A tensile strain of ∼0.2% was applied to monolayer WSe2 by placing it onto a dielectric rod structure with a nanosized gap. Excitons were localized in the nanogap sites, resulting in the generation of linearly polarized single-photon emission with a g(2) of ∼0.1 at 4 K. Additionally, we measured the abrupt change in polarization of single photons with respect to the nanogap size. Our robust spatial and polarization control of emission provides an efficient way to demonstrate deterministic and scalable single-photon sources by integrating with nanocavities.

Polarized ultraviolet emitters with Al wire-grid polarizers fabricated by solvent-assisted nanotransfer process.

Polarized ultraviolet (UV) emitters are essential for various applications, such as photoalignment devices for liquid crystals, high-resolution imaging devices, highly sensitive sensors, and steppers. To increase the high polarization ratio (PR) of a UV emitter, the grating period should be decreased than that of the visible emitter. However, the fabrication of the short period grating directly on UV emitters is still limited. In this study, we demonstrate that 200, 100, and 50 nm period aluminum (Al)-based wire-grid polarizers (WGPs) can be fabricated directly on UV emitters by a solvent-assisted nanotransfer process. The UV emitter with a grating period of 100 nm shows a PR of 84%, and an electroluminescence efficiency that is 22.5% and 48% higher than those of UV emitters with 50 nm and 200 nm period WGPs, respectively, due to the increased photon extraction efficiency (PEE). The higher PEE is attributed to the optical cavity property of the Al metal reflector with low light loss and the surface plasmon effect of the Al grating layer.

Self-Powered Chemical Sensing Driven by Graphene-Based Photovoltaic Heterojunctions with Chemically Tunable Built-In Potentials.

Ultralow power chemical sensing is essential toward realizing the Internet of Things. However, electrically driven sensors must consume power to generate an electrical readout. Here, a different class of self-powered chemical sensing platform based on unconventional photovoltaic heterojunctions consisting of a top graphene (Gr) layer in contact with underlying photoactive semiconductors including bulk silicon and layered transition metal dichalcogenides is proposed. Owing to the chemically tunable electrochemical potential of Gr, the built-in potential at the junction is effectively modulated by absorbed gas molecules in a predictable manner depending on their redox characteristics. Such ability distinctive from bulk photovoltaic counterparts enables photovoltaic-driven chemical sensing without electric power consumption. Furthermore, it is demonstrated that the hydrogen (H2 ) sensing properties are independent of the light intensity, but sensitive to the gas concentration down to the 1 ppm level at room temperature. These results present an innovative strategy to realize extremely energy-efficient sensors, providing an important advancement for future ubiquitous sensing.

National Trends of Meniscectomy and Meniscus Repair in Korea.

BACKGROUND: Meniscus surgeries are frequently performed in orthopaedics. However, their current status is not well known in many countries, including Korea. This study aimed to investigate the national trends of meniscus surgery in Korea. METHODS: Information from the national database was acquired through the Korean Health Insurance Review and Assessment Service from 2010 to 2017. All cases coded as meniscectomy or meniscus repair were included. The total number and incidence of cases of meniscus surgery per 100,000 persons were determined, and the results were stratified by age and gender. The meniscus repair ratio for the total number of meniscus surgeries was evaluated. RESULTS: The total number and incidence of meniscectomy cases were 65,752 and 137, respectively, in 2010, which increased to 74,088 and 154, respectively, in 2017. The number of meniscectomies increased by 12.67% in 8 years. The total number and incidence of meniscus repair cases were 9,055 and 18, respectively, in 2010, which increased to 14,947 and 31 in 2017. The number of meniscus repairs increased by 65.04%. The meniscus repair ratio was 12.1% in 2010, which increased to 16.8% in 2017. The highest peak was noted for patients who underwent meniscus surgeries in their 50s and 60s. Meniscectomy was performed more frequently in women (57%) than in men (43%), whereas repair was performed more frequently in men (54%) than in women (46%) over the study period. CONCLUSION: The total number and incidence of meniscus surgeries increased from 2010 to 2017; the number and incidence of meniscus repair procedures increased more rapidly than those of meniscectomy, with the peak treatment age for both surgeries being in the 50s and 60s. The current study will contribute to understanding the epidemiology of meniscus surgery, its prevention, and cost-saving measures in Korea.

Yellow-red light-emitting diodes using periodic Ga-flow interruption during deposition of InGaN well.

We report a possible way to extend the emission wavelength of InyGa1-yN/InxGa1-xN quantum-well (QW) light-emitting diodes (LEDs) to the yellow-red spectral range with little degradation of the radiative efficiency. The InyGa1-yN well with high indium (In) content (HI-InyGa1-yN) was realized by periodic Ga-flow interruption (Ga-FI). The In contents of the HI-InyGa1-yN well and the InxGa1-xN barrier were changed to manipulate the emission wavelength of the LEDs. An In0.34Ga0.66N/In0.1Ga0.9N-QW LED, grown by continuous growth mode (C-LED), was prepared as a reference. The photoluminescence (PL) wavelengths of the HI-InyGa1-yN/InxGa1-xN QW LEDs were changed from 556 to 597 nm. The PL intensity of the HI-InyGa1-yN/InxGa1-xN LED with a peak wavelength of 563 nm was 2.7 times stronger than that of the C-LED (λ = 565 nm). The luminescence intensity for the HI-InyGa1-yN/InxGa1-xN QW LED emitting at 597 nm was stronger than those of the other LED samples with shorter wavelengths. Considering the previous works on degradation in crystal quality and increase in the quantum-confined Stark effect with increasing In content in InGaN, the approach in this work is very promising for yellow-red InGaN LEDs.

Optical characteristics of InGaN/GaN light-emitting diodes depending on wafer bowing controlled by laser-treated grid patterns.

We evaluated the effects of grid patterns (GPs) realized on 2-inch sapphire substrates by simple laser treatment on the device characteristics of InGaN/GaN light-emitting diodes (LEDs). The degrees of wafer bowing for the LEDs with distances between the GPs of 1 (GP1-LED), 2 (GP2-LED), and 3 mm (GP3-LED) were 100.05, 100.43, and 101.59 µm, respectively, which are significantly improved compared to that (108.06 µm) of a conventional LED (C-LED) without GPs. Consequently, a blue-shift of the emission wavelength for the GP-LEDs was observed compared to the C-LED via alleviation of the quantum-confined stark effect. A comparative study of the fluorescence microscopy images of the C-LED and GP2-LED samples showed a significant reduction of threading dislocations as a result of the GPs. In the electroluminescence mapping results for the entire 2-inch region, the standard deviations of the emission wavelengths were 1.64, 1.49, and 2.55 nm for the GP1-LED, GP2-LED, and GP3-LED samples, respectively, which are smaller than that of the C-LED (2.66 nm). In addition, the average output power of the GP2-LED was 8.5% higher than that of the C-LED.

Beneficial Effects of Traditional Seasonings on Quality Characteristics of Fermented Sausages.

Though traditional seasonings are widely used in many dishes, however, no attention has been paid to the investigation of their effects on quality characteristics of food products. The present investigation was undertaken to study the effects of incorporating several traditional seasonings including doenjang (fermented soybean paste), gochu-jang (red pepper paste), fresh medium-hot, and hot peppers, and fresh garlic on the lipid oxidation, cholesterol content and sensory characteristics of fermented sausages. Six fermented sausage treatments (5 with 1% (w/w) each test seasoning and 1 without added test seasoning (control) were prepared. The addition of seasonings generally had beneficial effects on the improvement of fermented sausage's quality however the effects differed depending on the each type of seasonings added. Significant lower pH values were found in all fermented sausages made with the seasonings while, lower levels of lipid oxidation were found in the treatments with hot peppers and garlic as compared with the control (p<0.05). The treatment with seasonings did not cause color or texture defects in the products whereas the sausages made with gochu-jang had significantly higher Commission International de l'Eclairagea* (redness) value in comparison with the control. Noticeably, incorporating doenjang, medium-hot peppers, hot peppers and garlic resulted in reduction of 26.50, 32.54, 47.04, and 48.54 mg cholesterol/100 g samples, respectively (p<0.05). Higher scores for the sensory traits such as aroma, taste, color and acceptability were also given for the sausages made with seasonings. The current work demonstrates that the test seasonings represent potentially natural ingredients to be used for producing healthier fermented sausages.

Cholesterol-lowering and lipid oxidation reduction potentials of traditional seasonings in Salchichon dry-fermented sausages.

Five different natural/traditional seasonings including doenjang (fermented soybean paste), gochu-jang (red pepper paste), fresh medium-hot and hot peppers, and garlic were used, and 1 % (w/w) each was incorporated into formulations of Salchichon fermented sausage type. After ripening for 51 days, the products were assessed for quality parameters, lipid oxidation, cholesterol content and sensory characteristics. In general, incorporation of the seasonings did not cause color or texture defects whereas it had beneficial effects on improvement of product's quality; however the effects differed depending on each type of seasonings added. Noticeably, most treatments with the seasonings significantly reduced the lipid oxidation. Additionally, incorporating doenjang, gochu-jang, medium-hot peppers, hot peppers and garlic resulted in reduction of 32.03, 28.96, 36.30, 19.53 and 33.03 mg cholesterol/100 g sample, corresponding to 26.78, 24.21, 30.35, 16.33 and 27.61 %, respectively. Higher scores for the sensory traits such as aroma, taste, color and acceptability were also observed for the samples with seasonings. The current work demonstrated that the tested seasonings represent potentially natural ingredients for producing healthier Salchichon fermented sausages.

MPFL reconstruction with proximal rather than distal femoral tunnel position leads to less favorable short-term results.

BACKGROUND: This study aimed to compare the clinical and radiological outcomes of medial patellofemoral ligament (MPFL) reconstruction (MPFLR) between anatomic femoral tunnel positions: proximal (near adductor tubercle [AT]) and distal (near medial epicondyle [ME]). HYPOTHESIS: MPFLR with the proximal femoral tunnel position has worse clinical and radiological outcomes than those with the distal femoral tunnel position. PATIENTS AND METHODS: Fifty-five patients who underwent isolated MPFLR with proximal or distal femoral tunnels with at least 2 years of follow-up were retrospectively analyzed. Based on postoperative CT images, 28 patients were classified as group AT and the remaining 27 patients were classified as group ME. The International Knee Documentation Committee, Lysholm, Tegner, Kujala scores, and complications were evaluated. Radiologically, the Caton-Deschamps Index (CDI), patellar tilt angle, patellofemoral osteoarthritis (PFOA), patellofemoral cartilage status by the International Cartilage Repair Society (ICRS) grade, bone contusion, and MPFL graft signal intensity were evaluated. RESULTS: All clinical scores significantly improved in both groups (p<0.01). No statistically significant difference was noted between the two groups in regards to their preoperative demographic data, postoperative clinical scores, complications, or radiological findings (CDI, patellar tilt angle, PFOA, bone contusion, and graft signal intensity). The group AT had worse cartilage status on the medial facet of the patella (p=0.02). The ICRS grade for the medial facet of the patella statistically progressed in group AT compared to group ME (p=0.04) as well. DISCUSSION: Both groups showed significantly improved clinical outcomes. However, for the medial facet of the patella, MPFLR with the proximal femoral tunnel position had worse cartilage status and ICRS grade progression than those with the distal femoral tunnel position. LEVEL OF EVIDENCE: III; retrospective comparative study.

Salience signaling and stimulus scaling of ventral tegmental area glutamate neuron subtypes.

Ventral tegmental area (VTA) glutamatergic neurons participate in reward, aversion, drug-seeking, and stress. Subsets of VTA VGluT2+ neurons are capable of co-transmitting glutamate and GABA (VGluT2+VGaT+ neurons), transmitting glutamate without GABA (VGluT2+VGaT- neurons), or co-transmitting glutamate and dopamine (VGluT2+TH+ neurons), but whether these molecularly distinct subpopulations show behavior-related differences is not wholly understood. We identified that neuronal activity of each VGluT2+ subpopulation is sensitive to reward value but signaled this in different ways. The phasic maximum activity of VGluT2+VGaT+ neurons increased with sucrose concentration, whereas VGluT2+VGaT- neurons increased maximum and sustained activity with sucrose concentration, and VGluT2+TH+ neurons increased sustained but not maximum activity with sucrose concentration. Additionally, VGluT2+ subpopulations signaled consummatory preferences in different ways. VGluT2+VGaT- neurons and VGluT2+TH+ neurons showed a signaling preference for a behaviorally-preferred fat reward over sucrose, but in temporally-distinct ways. In contrast, VGluT2+VGaT+ neurons uniquely signaled a less behaviorally-preferred sucrose reward compared with fat. Further experiments suggested that VGluT2+VGaT+ consummatory reward-related activity was related to sweetness, partially modulated by hunger state, and not dependent on caloric content or behavioral preference. All VGluT2+ subtypes increased neuronal activity following aversive stimuli but VGluT2+VGaT+ neurons uniquely scaled their magnitude and sustained activity with footshock intensity. Optogenetic activation of VGluT2+VGaT+ neurons during low intensity footshock enhanced fear-related behavior without inducing place preference or aversion. We interpret these data such that VTA glutamatergic subpopulations signal different elements of rewarding and aversive experiences and highlight the unique role of VTA VGluT2+VGaT+ neurons in enhancing the salience of behavioral experiences.

Correlation between oxygen flow-controlled resistive switching and capacitance behavior in gallium oxide memristors grown via RF sputtering.

We studied on the bipolar resistive switching (RS)-dependent capacitance of Ga2O3 memristors, grown using controlled oxygen flow via a radio frequency sputtering process. The Ag/Ga2O3/Pt memristor structure was employed to investigate the capacitance changes associated with RS behavior and oxygen concentration. In the low-resistance state (LRS), capacitance increased by over 60 times compared to the high-resistance state (HRS). Furthermore, in the HRS state, increasing the oxygen flow from 0 to 0.3 sccm resulted in an 80 % decrease in capacitance, while in the LRS state, capacitance increased by 128 %. These results indicate that RS-dependent capacitance in Ga2O3 memristors is influenced by the density of oxygen vacancies. The presence of oxygen vacancies affects charge storage capacity and capacitance, with higher oxygen concentrations leading to reduced capacitance in HRS and increased capacitance in LRS. The results contribute to the understanding of the capacitance behavior in Ga2O3 memristors and highlight the significance of oxygen vacancies in their operation.

Effect of Posterior Tibial Slopes on Graft Survival Rates at 10 Years After Primary Single-Bundle Posterior Cruciate Ligament Reconstruction.

BACKGROUND: Recent biomechanical studies have reported that stress on the posterior cruciate ligament (PCL) graft increases as the posterior tibial slope (PTS) decreases (flattened) in knees with single-bundle (SB) and double-bundle PCL reconstruction. Clinical studies of SB PCL reconstruction have shown that a flattened PTS is associated with a lesser reduction in posterior tibial translation. There is no long-term study on the clinical outcomes and graft survival rates of SB PCL reconstruction based on the medial and lateral PTSs measured on magnetic resonance imaging. HYPOTHESIS: Flattened medial and lateral PTSs are associated with poor clinical outcomes and graft survival rates at a minimum 10-year follow-up after SB PCL reconstruction. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: In this cohort study, we retrospectively reviewed 46 patients (mean age, 28.8 ± 9.9 years) who underwent primary SB PCL reconstruction between 2000 and 2009. They were followed up for a minimum of 10 years. The medial and lateral PTSs were measured on preoperative magnetic resonance imaging. As a previous study reported that a steeper medial or lateral PTS showed a higher risk of anterior tibial translation at thresholds of 5.6° and 3.8°, respectively, the patients were divided into 2 groups based on the cutoff values of both the medial (≤5.6° vs >5.6°) and lateral (≤3.8° vs >3.8°) PTSs. Clinical scores (International Knee Documentation Committee subjective score, Lysholm score, and Tegner activity score), radiological outcomes (side-to-side difference [SSD] on stress radiography and osteoarthritis progression), and graft survival rates were compared between the groups at the last follow-up. RESULTS: All clinical scores and the progression of osteoarthritis demonstrated no significant difference between the 2 subgroups of both the medial and lateral PTS groups. The mean SSD on stress radiography after SB PCL reconstruction was significantly greater in patients with a medial PTS ≤5.6° than in patients with a medial PTS >5.6° (8.4 ± 3.9 vs 5.1 ± 2.9 mm, respectively; P = .030), while the lateral PTS subgroups after SB PCL reconstruction demonstrated no significant difference. The minimum 10-year graft survival rate was significantly lower in patients with a medial PTS ≤5.6° (68.4% vs 92.6%, respectively; P = .029) and a lateral PTS ≤3.8° (50.0% vs 91.7%, respectively; P = .001). CONCLUSION: A flattened medial PTS (≤5.6°) was associated with an increased SSD on stress radiography, and both flattened medial (≤5.6°) and lateral (≤3.8°) PTSs resulted in lower graft survival rates at a minimum 10-year follow-up after primary SB PCL reconstruction.