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Recovery of normal knee kinematics is critical for improving functional outcomes and patient satisfaction after total knee arthroplasty (TKA). The kinematics pattern after TKA varies from case to case, and it remains unclear how to reproduce normal knee kinematics. The present study aimed to evaluate rotational knee kinematics and soft-tissue balance using a navigation system and to assess the influence of intraoperative soft-tissue balance on the rotational knee kinematics. We evaluated 81 osteoarthritic knees treated with TKA using a posterior stabilized (50 knees) or cruciate retaining (31 knees) prosthesis. Rotational kinematics were assessed at 0, 30, 45, 60, and 90 degrees flexion angles by using a computer-assisted navigation system. Correlation between femorotibial rotational position and measured soft tissue balance was assessed by using Spearman's rank correlation coefficient. Rotational soft-tissue balance (the median angle of rotational stress) was significantly correlated with rotational kinematics (rotational axis of the femur relative to the tibia throughout the range of motion) at all measured angles after TKA. The correlation coefficients between the median angle of rotational stress and rotational kinematics were 0.97, 0.80, 0.74, 0.71, and 0.70 at 0, 30, 45, 60, and 90 degrees of flexion, respectively (p-values

Objectives The concept of locomotive syndrome (LS) and its evaluation method, the LS risk test, have been applied in an integrated manner to capture the decline in mobility resulting from musculoskeletal disorders. The purpose of this study was to evaluate the impact of total knee arthroplasty (TKA) in the elderly with knee osteoarthritis, a common disorder found in LS. Methods A total of 111 patients were registered prior to TKA and postoperatively followed up for 1 year. Three components of the LS risk test (the two-step test, stand-up test, and Geriatric Locomotive Function Scale-25) were assessed pre- and postoperatively. Results After surgery, all three components of the test showed significant improvements from the baseline. The ratio of Stage 3 LS patients (progressed stage of decrease in mobility) reduced from 82.3% to 33.9% postoperatively. There was no significant difference in the degree of change in the scores between the younger (60–74 years) and older (≥75 years) age groups. Conclusions We found that TKA has a major impact in preventing the progression of LS in patients with knee osteoarthritis. The LS risk test is a feasible tool for the longitudinal evaluation of patients with musculoskeletal diseases of varying severity and with multiple symptoms.

Original Article, [Purpose]This paper proposes a method to convert the coordinates specified for the center of foot pressure (COP) measurement plate to the coordinates for which the postural sway direction of a subject is the reference axis. [Method and Result] The COP was measured during the period from the tandem open-leg standing position to the one-leg standing position on the front limb. The analysis period was 1 s immediately after the one-leg standing position began. The reference axis direction was determined by two ways. The movement direction was calculated for each observation point and converted into the direction at every 30°. The direction that was the mode was set as the direction of the reference axis, and the maximum sway range was calculated. In addition, the movement direction was classified into groups of 30° each, and the total distance traveled between the observation points was calculated for each group. The direction for which the total distance was the maximum was set as the direction of the reference axis, and the maximum sway range was calculated. For each trial, the direction of the reference axis as determined based on the mode differed from that determined based on the total distance. [Conclusion]It was possible to rotate the coordinates meaningfully about the COP. It is suggested that the degree of sway can be assessed without specifying the position of the foot on the measuring plate.【目的】COPの測定板で規定された座標から、 被験者の動揺方向を基準軸とする座標に変換する手法を提案すること。 【方法と結果】タンデム開脚立位から前方下肢での片脚立位をとらせ、 COPを計測した. 片脚立位開始直後の1秒間を解析区間とした。 観測点間ごとに移動方向を算出し、 30°ごとの方向に変換した。 その最頻値となる方向を基準軸方向とし、 その最大動揺幅を求めた。 また、 移動方向を30°ごとのグループに分け、 グループごとに観測点間移動距離の総和を求めた。 総和が最大となった方向を基準軸方向とし、 その最大動揺幅を求めた。 頻度による基準軸も移動距離総和による基準軸も、 どちらも試行ごとにその方向は異なっていた。 【結語】人のCOPにおいて意味のある座標の回転を行うことが実現できた。 測定板に足部を置く位置を規定することなく、 動揺の程度を評価できることが示唆された。

Ferrets are animals that are known to be susceptible to influenza A virus (IAV) infection. To evaluate the risk of IAV transmission from diseased ferrets to humans, we performed a serosurvey to detect specific antibodies against the H1, H3, H5, and H7 subtypes of IAV. We found a high positive rate of the H1 (24.1%) and H3 (5.2%) subtypes in pet ferrets by using an enzyme-linked immunosorbent assay for hemagglutinin proteins. The results were confirmed by the virus-neutralization test for representative antibody-positive serum samples. We also detected hemagglutinin and neuraminidase genes in two ferrets showing acute respiratory illness and whose owner was diagnosed with IAV infection; a human H1N1pdm virus was isolated from one of these ferrets. Our findings suggest that attention should be paid for IAV infection from humans to ferrets, and vice versa.

Purpose Posterior capsular contracture causes stiffness during knee extension in knee osteoarthritis. Furthermore, in posterior-stabilized total knee arthroplasty (PS-TKA), a unique design such as the cam mechanism could conflict with the posterior capsule (PC) causing flexion contracture (FC). However, few studies have focused on the anatomical aspects of the PC. This study aimed to investigate the anatomical site and forms of posterior capsular attachment to the femoral cortex, and to evaluate the efficacy of posterior capsular release for FC by assessing changes in knee extension angles using a navigation system. Methods Attachment sites of the PC were investigated in 10 cadaveric knees using computed tomography. PS-TKA was performed in six cadaveric knees using a navigation system to evaluate the efficacy of posterior capsular release for FC. Posterior capsular release was performed stepwise at each part of the femoral condyle. Results The gastrocnemius tendon and PC were integrally attached to the femoral cortex at the medial and lateral condyles, whereas the PC at the intercondylar fossa was independently attached directly to the femoral cortex. Moreover, the PC at the intercondylar fossa was attached most distally among each femoral condyle. Posterior capsular release at the intercondylar fossa allowed 11.4° ± 2.8° improvement in knee extension. This angle was further improved by 5.5° ± 1.3°, after subsequent capsular release at the medial and lateral condyles. Conclusion The forms and sites of posterior capsular attachment differed based on the part of the femoral condyle. Stepwise posterior capsular release was effective for FC in PS-TKA. Level of evidence III.

Background: To preserve the ability to perform physical activities among the elderly, the concept of locomotive syndrome and its evaluation method, the locomotive syndrome risk test, have been applied in an integrated manner to capture the decline in mobility resulting from musculoskeletal disorders. During treatment, physicians can use the locomotive syndrome risk test to evaluate the impact of each therapy such as total knee arthroplasty for knee osteoarthritis, a common disorder found in locomotive syndrome. The purpose of this study was to evaluate the impact of total knee arthroplasty in the elderly with respect to locomotive syndrome.Methods: A total of 111 patients were registered at six hospitals prior to total knee arthroplasty and postoperatively followed up for 1 year. Three components of the locomotive syndrome risk test (the two-step test, stand-up test, and geriatric locomotive function scale-25) were assessed together with the EuroQol-5 Dimension scores pre- and postoperatively.Results: Post surgery, all three components of the locomotive syndrome risk test as well as the EuroQol-5 Dimension utility score showed significant improvements from the baseline (two-step test, 1.01±0.25 to 1.12±0.21; stand-up test, 2.02±1.14 to 2.38±1.20; geriatric locomotive function scale-25, 38.3±15.8 to 18.7±16.6, mean ± standard deviation). The ratio of stage 3 locomotive syndrome patients (progressed stage of decrease in mobility, restricting social engagement) reduced from 82.3% to 33.9% postoperatively. There was no significant difference in the degree of change in the three test scores between the younger (60-74 years) and older (≥75 years) age groups. Conclusions: We found that total knee arthroplasty has a major impact in preventing the progression of locomotive syndrome in patients with knee osteoarthritis. The locomotive syndrome risk test is a feasible tool for longitudinal evaluation of patients with musculoskeletal diseases of varying severity and with multiple symptoms.Trial registration: This study was registered as UMIN000023595 (10/08/2016)

Original Article, In order to prevent falls, it is necessary to know how the individual standing position is unstable. By grasping the normal standing position of the individual, we were able to observe the fluctuation of instability within individuals, which may lead to more effective prevention of falls. The purpose of this study is to explore the suitable sampling frequency to fit the center of pressure (COP) at multiple resting positions of the individual. In addition, we aim to estimate the parameters of a specific ARIMA (p, d, q) model. The two subjects were females in their 50s, and the COP at the open-eyes open-legs standing position was measured for 30 seconds at a sampling frequency of 100Hz. A total of 40 trials were obtained for each subject. Data sets corresponding to measurement at 50Hz, 25Hz, 20Hz, 10Hz were created by downsampling. As a result of fitting ARIMA models to these data, the two subjects had stationarity in the first order differential series in many trials. When the number of trials unsuitable for the ARIMA model is the smallest, the sampling frequency was 20Hz. Furthermore, (1, 1, 2), (2, 1, 0), and (2, 1, 2) are considered candidates for the parameters (p, d, q).人の転倒を防止するために、 個々の立位がどのように不安定であるか知ることが必要である。 個人の通常の立位状況を把握することができれば、 個人内での不安定さの変動がわかり、 より有効な転倒防止につなげられると考えた。 本研究の目的は、 同一個人の複数回の安静立位時の足圧中心(Center of Pressure:COP)を特定のARIMA(p, d, q)モデルにあてはめるために適したサンプリング周波数と次数(p, d, q)を探索することである。 対象者を50歳代女性2名とし、 開眼開脚立位でのCOPを、 サンプリング周波数100Hzで30秒間計測し、 被験者ごとに40試行のデータを得た。 ダウンサンプリングにより50Hz、 25Hz、 20Hz、 10Hzでの計測に相当するデータセットも作成した。 これらのデータに対し、 ARIMAモデルのあてはめを試みた結果、 両名とも1階差分系列で定常性が多くみられた。 ARIMAモデルにあてはまらない試行数を最も少なくするサンプリング周波数は、 20Hzであり、 次数(p, d, q)は、 (1, 1, 2)、 (2, 1, 0)、 (2, 1, 2)が候補と考えられた。

Background The anterior cruciate ligament is composed of two functional bundles and is crucial for knee function. There is limited understanding of the role of each individual bundle and the influence on length pattern due to difference in bone tunnel position under loading conditions throughout the range of motion. We measured point to point length between the femoral and tibial footprints of the ligament throughout the range of motion in normal knees, under normal loading conditions, and investigated length pattern changes secondary to differences in the femoral footprint. We hypothesized that anteromedial and posterolateral bundles have complementary roles, and the ligament length pattern is influenced by the footprint position. Methods We studied the squat movements of six healthy knees and measured point to point footprint distance. The footprint distances were measured after changing them to be 10% lower, 10% shallower, and both 10% lower and shallower than the defined anatomical femoral footprint. Results Average length changes of 12.0 and 14.1 mm from maximum extension (10°) to deep flexion (150°) were observed when the anteromedial and posterolateral bundles were defined by the default anatomical position. Maximum and minimum length were reached during full extension and flexion for both the anteromedial and posterolateral bundles, respectively. At 10% lower, length increased 2.2 mm over the default value in both the anteromedial and posterolateral lengths. At 10% shallower, decreases of 4.1 mm and 3.9 mm were observed compared with the default anteromedial and posterolateral lengths, respectively. In the 10% lower and 10% shallower position, anteromedial and posterolateral lengths decreased 2.1 mm and 1.9 mm compared with the default value, respectively. Conclusions The anteromedial and posterolateral bundles have a complementary role. Femoral footprint position defined in the lower direction leads to stronger tension during extension, while the higher and shallower direction leads to isometry during flexion, and the deeper direction leads to laxity during flexion. The target bone tunnel position is that the anteromedial bundle should not to be too low and too deep to maintain function of bundle with less change in length. In addition, the posterolateral bundle should be somewhat lower and/or deeper than the anteromedial, with the expectation that it will function to induce stronger tension at the extended position. However, we should avoid lower position when we cannot prepare a sufficient diameter of reconstructed bundle to avoid re-injury due to excessive tension.

Original Article, The purpose of this study is to estimate the tensile force of two weeds, rescuegrass (Bromus catharticus) and green foxtail (Setaria viridis) using diameter or height. We select 45 samples of rescuegrass and 50 of green foxtail. We measured resistance force against weed-pulling, diameter at the ground surface position, grass height, and soil hardness. Group A includes 45 rescuegrass samples, Group B includes 50 green foxtail samples, and Group C includes samples of both types of weed. We derived simple regression models and determined the best among them according to the coefficients of determination. It is valid to estimate the tensile force using the short diameter for all groups. However, it is not effective to use height as an explanatory variable for each group, even if some nonlinear regression models do so.本研究の目的は、 イヌムギ(Bromus catharticus)とエノコログサ(Setaria viridis)ともに、 引張抵抗力の推定に地際径を説明変数に用いることが有効かどうか、 また、 引張抵抗力の推定に草丈が説明変数になり得るかどうか検証することである。 試料は、 イヌムギ45本、 エノコログサ50本とした。 これらの引張抵抗力、 地際径、 草丈、 土壌硬度を測定した。 試料は、 イヌムギ群(A群)、 エノコログサ群(B群)、 混合群(C群)に群分した。 単回帰モデルを導出し、 決定係数に応じて最適なものを決定した。 地際径の短径を説明変数に用いることは、 A群、 B群、 C群ともに有効であった。 一方、 草丈を説明変数として用いることは、 非線形回帰モデルであっても、 すべての群で有効とはいえなかった。

Rheumatoid arthritis (RA) is characterized by chronic synovial inflammation with aberrant epigenetic alterations, eventually leading to joint destruction. However, epigenetic regulatory mechanisms underlying RA pathogenesis remain largely unknown. Here, we showed that Ubiquitin-like containing PHD and RING finger domains 1 (UHRF1) , a key molecule involved in maintenance of DNA methylation during cell division, is a central epigenetic regulator that orchestrates the suppression of expression of multiple factors that exacerbate RA. We found that murine arthritis tissue and human RA tissue, particularly synovial fibroblasts (SF), exhibit remarkable up-regulation of expression of Uhrf1. SF-specific Uhrf1 conditional knockout mice showed more severe arthritic phenotypes and apoptosis-resistant SF. Integrative analysis of the transcriptome and methylome showed that expression of several cytokines including Ccl20 was up-regulated in Uhrf1-deficient SF. In RA patients, disease activity scores, CCL20 expression, Th17 accumulation and apoptosis resistance were negatively correlated with UHRF1 expression in synovium. Finally, stabilization of UHRF1 by Ryuvidine administration diminished disease pathogenesis in arthritis model mice. Our results demonstrated that UHRF1 expressed in SF can contribute to suppression of multiple pathogenic events associated with RA such as Th17 recruitment, SF apoptosis and bone destruction, suggesting that targeting UHRF1 could represent a novel therapeutic strategy for RA.

Background The influence of tibial resection on the joint gap and on stability against posterior laxity in posterior cruciate ligament–retaining total knee arthroplasty (CR-TKA) remains unclear. In addition, there are no detailed reports regarding how much of the tibial attachment of the posterior cruciate ligament (PCL) is preserved during tibial resection. Our goals were to evaluate the influence of tibial resection on the intraoperative joint gap and on postoperative anteroposterior stability in a clinical population, and to assess the preserved area of the tibial PCL attachment using cadaveric knees. Methods In 20 consecutive patients, the joint gaps before and after tibial resection at 90° flexion and full extension were analyzed during CR-TKA, and anteroposterior stability was evaluated postoperatively. In 11 cadaveric knees, tibial resection with a thickness of 8, 10, 12, or 14 mm and a posterior slope of 3, 4, 5, 6, or 7° was simulated using computed tomography images, and the percentage of the preserved area of the attachment was calculated. Results The flexion gaps before and after tibial resection were 18.1 ± 1.9 mm and 18.4 ± 2.2 mm, respectively, with no statistically significant difference (p = 0.08). Similarly, the extension gap did not increase significantly before and after tibial resection (20.8 ± 2.5 mm and 21.0 ± 2.6 mm; p = 0.45). All knees maintained anteroposterior stability at the follow-up period (32.0 ± 1.9 months). The posterior slope of the tibial resection was 5.9 ± 1.4°, and the thickness of the lateral tibial resection was 10.4 ± 1.1 mm. The cutoffs to preserve more than 50% of the attachment were 10-mm thickness and 5° slope. Conclusions Our results showed that tibial resection did not influence the intraoperative joint gap or postoperative anteroposterior stability. However, our analysis demonstrated that increased amounts of tibial resection led to considerable damage to the attachment.

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To evaluate changes in midflexion rotational laxity before and after posterior-stabilized (PS)-total knee arthroplasty (TKA). Twenty-nine knees that underwent PS-TKA were evaluated. Manual mild passive rotational stress was applied to the knees, and the internal–external rotational angle was measured automatically by a navigation system at 30°, 45°, 60°, and 90° of knee flexion. The post-operative internal rotational laxity was statistically significantly increased compared to the preoperative level at 30°, 45°, 60°, and 90° of flexion. The post-operative external rotational laxity was statistically significantly decreased compared to the preoperative level at 45° and 60° of flexion. The post-operative internal–external rotational laxity was statistically significantly increased compared to the preoperative level only at 30° of flexion. The preoperative and post-operative rotational laxity showed a significant correlation at 30°, 45°, 60°, and 90° of flexion. Internal–external rotational laxity increases at the initial flexion range due to resection of both the anterior or posterior cruciate ligaments and retention of the collateral ligaments in PS-TKA. Preoperative and post-operative rotational laxity indicated a significant correlation at the midflexion range. This study showed that a large preoperative rotational laxity increased the risk of a large post-operative laxity, especially at the initial flexion range in PS-TKA. III.