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Abstract Purpose To evaluate the effect of untreated medial meniscal ramp lesions (MMRLs) on the tendon graft after anterior cruciate ligament (ACL) reconstruction and histological findings of medial meniscus (MM) in a porcine a model. Methods A total of 17 pigs were divided into two groups: (1) the untreated MMRL group (UM group, n = 9) and (2) intact MM group (n = 8) and euthanized 12 weeks after surgery. The specimens were then tested cyclically and loaded to failure. Side‐to‐side differences (SSDs) in translation under cyclic loading and structural properties were analyzed. Histological evaluation of the MM was also performed. Results No significant differences in the SSD in translation during the cyclic testing (UM group, 0.3 ± 0.4 mm; intact MM group, 0.1 ± 1.4 mm), upper yield load (UM group, 476.3 ± 399.9 N; intact MM group, 643.2 ± 302.9 N), maximum load (UM group, 539.5 ± 265.8 N; intact MM group, 705.8 ± 282.6 N), linear stiffness (UM group, 63.5 ± 39.0 N/mm; intact MM group, 73.7 ± 60.1 N/mm) and elongation at failure (UM group, −4.6 ± 16.3 mm; intact MM group, 2.3 ± 6.6 mm) were observed. However, the UM group had significantly worse Modified Mankin's histological grading scores (1.8 ± 0.4 [1–2] vs. 0 ± 0 [0]; p

Abstract Purpose We aimed to investigate whether a plate adapted to the anatomy of the proximal medial porcine's tibia would provide maintenance of the anterior gap (AG), posterior gap (PG) and posterior tibial slope (PTS). Methods Twenty‐seven porcine tibias were biomechanically evaluated by performing MOWHTO and placing TOMOFIX (n = 9), AC plate (n = 9) and TriS (n = 9) anteromedially. Cyclic testing (800 N, 2000 cycles, 0.5 Hz) was performed to investigate the PTS over time for MOWHTO. The particular displacement calculated from the maximum to the minimum point with the load‐displacement curve along the mechanical axis during cyclic testing, the final AG and PG changes at the osteotomy site, the increased PTS calculated by subtracting AG from PG after 2000 cycles were compared among the three groups. The displacement was evaluated by repeated‐measures analysis of variance (ANOVA), and changes in AG and PG and increased PTS were evaluated by one‐way ANOVA. The sample size for α and β errors were

Background: Hospital-related coronavirus disease 2019 (COVID-19) infection is of utmost concern among patients and health care workers. Expanding the use of telemedicine may be required in daily outpatient practice; however, the acceptance of telemedicine use is still low, especially among older patients. In an orthopedic practice, no studies have investigated potential factors that can contribute to changes in the acceptance of using telemedicine. Focusing on older outpatients with knee osteoarthritis (KOA), we hypothesized that a drastic surge in the number of patients with COVID-19 could trigger changes in attitudes regarding the acceptance of telemedicine use. Methods: A baseline survey was conducted after the first wave of the COVID-19 pandemic in Japan to obtain information on the willingness to use telemedicine among patients aged ?70 years who regularly consulted an orthopedic surgeon for KOA. A follow-up survey was subsequently conducted during the third wave of the pandemic period to assess changes in the acceptance of telemedicine use in response to the rapidly increasing number of patients with COVID-19. We compared the difference in acceptance of telemedicine use and knee pain status between the baseline and follow-up surveys. Results: In the baseline survey, 11 of 43 patients (25.6%) responded that they would be willing to use telemedicine. In the follow-up survey, patients' acceptance of telemedicine did not change, with the exact same number and percentage of patients who were willing to use telemedicine as in the baseline survey, despite that ?20% of patients reported improvement in their knee pain status. Discussion: Our findings indicate that older outpatients with KOA did not change their willingness to accept use of telemedicine, even with a drastically increased risk of hospital-related transmission of a potentially fatal infectious disease when visiting a hospital. The acceptance of telemedicine use among older patients might not be less sensitive to external environmental factors but instead might be more sensitive to patients' personal factors, such as anxiety for information technology and resistance to changes in their lifestyle.

Two elderly female patients with Kellgren–Lawrence grade 4 knee osteoarthritis (KOA) having varus knee deformity and retained hardware for internal fixation in either femur or tibia underwent total knee arthroplasty (TKA) using 3D templating and patient-specific instrumentation (PSI). TKA was performed to treat KOA by minimally removing or without removing the retained hardware for the internal fixation of distal femoral or tibial diaphyseal fractures. Throughout a 2-year follow-up period, no superficial or deep infection was observed. In additions, no radiological symptoms of suspected component loosening were observed. Furthermore, both patients can currently walk without using crutches. 3D templating and PSI in primary TKA for patients with retained hardware for internal fixation of femoral or tibial fractures are considered suitable treatment options for reducing surgical invasion.

Purpose: To investigate the biomechanical efficacy of medial meniscal ramp lesion (MMRL) repair in anterior cruciate ligament (ACL) reconstruction regarding the graft protection effect after cyclic loading. Methods: Specimens were randomized into 2 groups: (1) ACL reconstruction with unaddressed MMRL (Group U; n = 10), and (2) ACL reconstruction with repaired MMRL (Group R; n = 12). The specimens were tested cyclically (2,000 cycles, 0-40 N, 100 mm/min) in the direction of the native ACL and loaded to failure (100 mm/min) on a tensile tester. Statistically significant differences between the structural properties (length changes and anterior translations at the 100th, 500th, 1,000th, 1,500th, and 2,000th cycles, upper yield load, maximum load, linear stiffness, and elongation at failure) under cyclic loading and single-cycle loading were analyzed. Results: There were no significant differences in length changes and anterior translations at the 100th, 500th, 1,000th, 1,500th, and 2,000th cycles. There were no significant differences in upper yield load (82.4 ± 31.2 N in Group U, 90.0 ± 38.5 N in Group R, P = .62), maximum load (109.9 ± 28.6 N in Group U, 124.0 ± 56.4 N in Group R, P = .48), linear stiffness (12.1 ± 4.7N/mm in Group U, 12.5 ± 4.3 N/mm in Group R, P = .84), or elongation at failure (13.5 ± 7.3 mm in Group U, 16.6 ± 7.5 mm in Group R, P = .30). Conclusions: Simultaneous MMRL repair at the time of ACL reconstruction did not decrease length changes and anterior translations during cyclic loading. In addition, simultaneous MMRL repair at the time of ACL reconstruction did not contribute to better postoperative structural properties. Clinical Relevance: Simultaneous MMRL repair at the time of ACL reconstruction does not show a graft protective effect after cyclic loading. Graft elongation may occur during early rehabilitation.

A much higher cell voltage of ca. 2.5 V than that of the typical Li-S battery was successfully achieved by combining the 5 V-class, spinel-type LiNi0.5Mn1.5O4 (LNMO) as a cathode and the rubber-derived sulfur composite as an anode. The cycling performance of the cell was improved by the PVDF coating only the cathode and coating both the cathode and anode, in which the discharge capacity retention increased from ca. 45 % to ca. 60 %. On the other hand, there was no difference in the cycling performance between the cell with the PVDF coating only the anode and the cell without the PVDF coating both the cathode and anode. There was no difference between the cycling performance of the half-cell of the LNMO cathode with the PVDF coating and without the PVDF coating, indicating that the PVDF coating on the cathode side does not prevent degradation of the electrolyte solution on the cathode surface. These results suggest that the PVDF coatings of the cathode surface play an important role as a protective layer in preventing the direct contact and side reaction between the polysulfides and cathode surface, thus leading to improvement of the cycling performance.

A rubber-derived sulfur composite cathode material for the Li-S battery/Li-ion battery was synthesized by the vulcanization process of butadiene rubber as a polymer source and a large amount of sulfur. In this study, the higher vulcanization temperature of 450 °C and a larger amount of sulfur (rubber : sulfur = 1 : 10, mass/mass) than the mass production process of the rubber were applied. The rubber-derived sulfur composite has a large amount of sulfur, ca. 58 wt% and a stable cycling ability with a capacity of 400 mAh g−1 at 30 °C. The cells consisting of the rubber-derived sulfur composite as the cathode and SiO as the anode displayed a great potential as for the next-generation LIBs because of its both electrodes containing no transition metals, outstanding electrochemical properties and safety performance. The cell showed a superior high and low temperature performance from −20–80 °C for over 100 cycles and a good rate performance in which the capacity of ca. 600 mAh g−1 was obtained at the 5 C-rate at 60 °C. In addition, there were no thermal runaway and no evolution of hydrogen sulfide in the nail penetration test.

Background: There is no report yet on the application of telemedicine in orthopedic practice in Japan. With a focus on patients with KOA, we investigated the willingness of patients to use telemedicine by assessing factors such as the patient’s age, smartphone possession, hospital visiting time, and severity of KOA. Methods: Data of patients who regularly consulted orthopedic surgeons at our institutions from April 2020 to June 2020 were retrospectively analyzed using an electronic medical database. The patients were diagnosed with KOA according to clinical and radiological findings, according to the Kellgren-Lawrence (KL) classification. included were patients with KOA with KL classification above grade 2. All patients were asked: 1) whether they were willing to use telemedicine (Yes or No), 2) the reason why they answered Yes, 3) the reason why they answered No, 4) if they possessed a smartphone, 5) their numeric rating scale for pain at their last outpatient visit after the Sars-CoV-2 epidemic emerged, and 6) the time required for visiting hospital from their house. Patients were stratified into 2 groups depending on whether they answered Yes (Group Y) or No (group N). Comparisons between the groups concerning smartphone possession, NRS pain, hospital visiting times, and distribution of KL grade were made. Results: Only 36.7% of the patients with KOA said they were willing to use telemedicine. The average age of group Y was significantly younger than that of group N (67.9 ± 9.1 vs 73.1 ± 8.0, P = 0.0026) and the cutoff age was 70.0 years. In addition, the rate of smartphone possession was significantly higher in group Y than in group N (82.5% vs 34.5%, P < 0.001). Hospital visit times and the severity of KOA did not differ between the groups. Conclusion: Age is a barrier to the adoption of telemedicine.

Abstract On 15 January 2022, a massive underwater eruption occurred at the Hunga Tonga‐Hunga Ha'apai Volcano. The plume reached the mesosphere, and the eruption excited a significant atmospheric Lamb wave, which forced the tsunami. The complicated tsunami waveforms due to ocean‐atmosphere coupling prevented inferring the force history of the excitation. To address this, we analyze ocean surface gravity waves (OSWs) from 15 to 40 mHz, which are decoupled from the Lamb wave due to their slower phase velocities. Modeling these OSWs, we infer that the excitation started at 4:00 UTC with an amplitude of 1010 N and lasted for 5 hr, followed by a sub‐event at 8:40 UTC. The observations suggest an initial blowout of seawater above the summit and a subsequent outflow that excited a tsunami below 5 mHz. The 2 hr delayed OSW excitation from 6 to 15 mHz may indicate seawater inflow into the crater.

Abstract On 8 October 2023 UTC, significant tsunamis were observed around Japan without any major tsunamigenic earthquake, associated with a series of 14 successive minor earthquakes (mb = 4.5–5.4) near Sofugan in the Izu‐Bonin Islands. To examine the cause of this tsunami, we estimated the horizontal locations of the tsunami source and temporal history of the seafloor displacement, using the tsunami data recorded by the ocean‐bottom pressure gauges >∼600 km away. Our results showed the main tsunami source was an uplift located at a caldera‐like bathymetric feature near Sofugan, suggesting the involvement of caldera activity in the tsunami generation. The total seafloor uplift was estimated as ∼4 m, and the uplift amount of each event gradually increased over time, reflecting an accelerating occurrence of volcanic unrest of the submarine caldera within only a few hours.

In model-based control system design, redesign is required when the order of the plant model changes. It inhibits prospective design in the control system design procedure, consisting of “plant modeling” and “controller design.” Moreover, the problem of control structure often depends on experience and knowledge, and emphasis is more placed on how to determine the optimal parameters after the control structure is determined than on other crucial elements. This paper proposes methods based on the partial model matching method that does not require controller redesign when the order of the plant changes and for selecting the control structure by comparing the characteristics of several approaches, including the change of plant order, not taken into consideration so far in the literature. The proposed method can stabilize the plant by designing the controller for higher-order plants and adjusting its coefficients for order-changed lower-order plants.

Abstract The source imaging for offshore earthquakes using terrestrial geodetic data has a limited estimation performance due to the low data resolution. One approach to overcome this limitation is the use of seafloor geodetic data. In this study, we focus on tsunami-source data, which is the spatial distribution of vertical crustal displacements above the source area and can be derived from tsunami waveform records. We evaluate how the use of this spatial seafloor geodetic data improves the estimation of a rectangular fault model. Here, the fault model of the 2016 off-Fukushima earthquake in Japan, which was a shallow intraplate earthquake (M w 7.0), was estimated by three inversions: terrestrial Global Navigation Satellite System (GNSS) data only, tsunami-source data only, and a combination of the GNSS data and tsunami-source data. A Bayesian inversion approach was used to understand the distribution of the estimated fault parameters and their relationship. The results indicated that the terrestrial GNSS data have a low resolution for the analysis of the offshore earthquake, which resulted in a biased solution with large uncertainty. Conversely, the use of tsunami-source data significantly improved the resolution and reliability of source imaging and reduced the dependency among fault parameters. These results suggested that the high-spatial-resolution information of tsunami source is a powerful tool in source imaging of offshore shallow earthquakes. Moreover, the combined use of the two different geodetic data leads to a more robust estimation of fault parameters. We believe that the use of tsunami-source data is useful, not only for the post hoc source analysis, but also for estimating an earthquake rupture area just after a large earthquake, where GNSS data are currently used. Graphical Abstract

Abstract Ocean bottom pressure-gauge (OBP) records play an essential role in seafloor geodesy. Oceanographic fluctuations in OBP data, however, pose as a significant noise source in seafloor transient crustal deformation observations, including slow slip events (SSEs), making it crucial to evaluate them quantitatively. To extract the significant fluctuation phenomena common to multiple observation networks, including oceanographic fluctuations and tectonic signals, we applied principal component analysis (PCA) to the 3-year Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) OBP time series for 40 stations during 2016–2019. PCA could separate several oceanographic signals based on the characteristics of their spatial distributions, although evident transient tectonic signals could not be confirmed from the observed pressure records during this observed period. The spatial distribution of the first four principal components (PCs) reflected the common component, inclined component along sea depth, longitude component, and parabola-like pattern, respectively. By subtracting each PC (in particular, PC-2 and PC-4) from the time series, we could significantly reduce the sea depth dependence of OBP records, which has been highlighted in several previous studies and is also evident in this region. We interpreted PCs 2–4 as the reflection of the strength and meandering of ocean geostrophic currents based on a comparison with the PC spatial distribution of the numerical oceanographic models. In addition, to evaluate the ability of PCA to separate transient tectonic signal from OBP time series, including oceanographic fluctuations, we conducted a synthetic ramp assuming an SSE by rectangular fault and then applied PCA. The assumed synthetic tectonic signal could be separated from the oceanographic signals and included in the principal component independently depending on its amplitude, suggesting that the spatial distribution of each PC would change if the amplitude of the synthetic signal were sufficiently large. We propose a transient event-detection method based on the spatial distribution difference of a specific PC with or without a tectonic signal. We used the normalized inner product (NIP) between these PCs as the indicator of their similarities. This method can detect transient tectonic signals more significantly than the moment-magnitude scale of 5.9 from OBP records. Graphical Abstract

Abstract When the 2003 Tokachi-oki earthquake generated a large tsunami off eastern Hokkaido, Japan, it was detected by cabled ocean-bottom pressure gauges (OBPs) installed within the seismic source region. The OBP records included characteristic features of tsunami waveforms in the source region, indicating significant offset due to the permanent sea-bottom displacement, which can provide critical information about the earthquake source. However, no studies have considered the OBP tsunami data observed in the focal region for the source inversion of the Tokachi-oki earthquake. Here, in order to better understand the 2003 Tokachi-oki earthquake source, we estimate the spatial distribution of fault slip by conducting a joint inversion using two different datasets: tsunami data from four OBPs, located in the focal region and about 300 km away to the south, as well as Global Navigation Satellite System (GNSS) data obtained throughout Hokkaido and northern Honshu. Through our joint inversion, we found that the most dominant slip peak is located 40 km northwest from the hypocenter with an abnormally large slip of $$\sim$$ ∼ 15 m. This large slip may result from releasing a high amount of slip deficit accumulated by a stick–slip patch surrounded by stable slip regions on the southernmost Kuril subduction zone. By comparing the OBP observations and the synthetic tsunami waveforms derived from our fault model and other fault models, we conclude that the OBP tsunami data recorded within the focal region better constrained the magnitude and the location of the slip compared to other geophysical data. Graphical Abstract

Abstract On 8 October 2023, mysterious tsunamis with a maximum wave height of 60 cm were observed in Izu Islands and southwestern Japan, although only seismic events with body‐wave magnitudes mb 4–5 have been documented to the west of Sofugan volcano. To investigate the source process, we analyze tsunami waveforms recorded by an array network of ocean bottom pressure gauges. Stacked waveforms of pressure gauge records suggest recurrent arrivals of multiple wave trains. Deconvolution of the stacked waveforms by tsunami waveforms from an earlier event revealed over 10 source events that intermittently generated tsunamis for ∼1.5 hr. The temporal history of this sequence corresponds to the origin times of T‐phases estimated by an ocean bottom seismometer and of the seismic swarm, implying a common origin. Larger events later in the sequence occurred at intervals comparable to the tsunami wave period, causing amplification of later phases of the tsunami waves.

Abstract Long-term continuous observation of seafloor pressure is effective for detecting seafloor vertical deformations that are associated with transient tectonic phenomena such as slow slip events. Since the aseismic slip event prior to the 2011 Tohoku earthquake, several discoveries have been made on spontaneous slow slip events and various other types of slow earthquake along the Japan and Kuril Trenches. Seafloor observation network for earthquakes and tsunamis along the Japan Trench (S-net) is expected to provide invaluable information on slow slip activities via geodetic signals that are detected by pressure observation. This study inspects the quality of the S-net pressure data in view of seafloor geodesy by comparison with records obtained by more than 100 autonomous ocean bottom pressure recorders (OBPRs) deployed along the Japan Trench. OBPRs have long been standard tools in seafloor geodesy, and the data collected are considered a benchmark in terms of quality. Most of the S-net stations showed noise levels that are considerably higher than those of the OBPRs over periods of more than 2 d. We speculate that a strong correlation between pressure and temperature accounts for much of the long-term noise. In this study, the temperature-dependent fluctuation component was estimated by prediction filtering and removed from the original data, leading to a significant reduction in the noise level at 51 stations, which reached levels almost equivalent to those of OBPRs. Although no significant pressure changes have been identified as associated with the 2018 Boso SSE or repeated tremor bursts in the northern Japan Trench thus far, our findings indicate that these stations are sufficiently sensitive to detect slow slip events occurring nearby.

Abstract The 2011 Tohoku-Oki earthquake generated a surprisingly large near-trench slip, and earth scientists have devoted significant attention to understanding why. Some studies proposed special rupture mechanisms, such as extensive dynamic frictional weakening; others simulated this near-trench slip behavior without supposing the extensive dynamic weakening. However, we have not reached a decisive conclusion for this question due to limited spatial near-trench slip resolution. Hence, in this study we use new tsunami data recorded just above the large slip area in addition to offshore and onshore geodetic data to improve the spatial resolution of stress release in the Tohoku-Oki earthquake and quantitatively examine the mechanical state of the plate interface. A maximum slip of 53 m reaching the trench and an insignificant stress drop (

Abstract Ocean-bottom pressure gauges of wide and dense ocean-bottom observation networks around Japan, S-net and DONET, observed ocean waves caused by the Tonga eruption that started at approximately 13:00 JST (UTC + 0900) on January 15, 2022. We scrutinized the waveform records of the arriving ocean waves to evaluate their nature and found two significant disturbances between 20:00 and 21:00 and after 22:00. The first disturbance with a positive-polarity pulse dominated by long-period components (1000–3000 s) arrived at S-net and DONET stations between 20:00 and 21:00 from the southeast, corresponding to the direction of the short great circle between Tonga and Japan. This arrival was much earlier than expected for a direct tsunami from the volcano and can be explained by assuming that the waves propagated along the short great circle path at a velocity of approximately 300 m/s. After 22:00, significant phases dominated by relatively shorter period components (

Heat-induced maturation of homoserine dehydrogenase from a hyperthermophilic archaeon requires conformational changes within the catalytic region.