Analysis of policy options to address Japanʼs declining population, shrinking birthrate, and aging society

Based on an analysis of the housing market, this study measures how Japanʼ s declining population and aging society influences its economic system in order to clarify empirically the effects of various policies to address these issues. Specifically, we simulate the decline in housing asset prices brought about by these population changes by 2040 and estimates the effects of three policies designed to suppress this decline: a) accepting more immigrants, b) raising the retirement age, and c) promoting the social advancement of women. The results obtained show that a) staving off the decline in asset prices would be impossible unless 40 million working-age immigrants were encouraged to migrate to Japan by 2040, that b) raising the retirement age to 70 or 75 would have a significant effect on maintaining residential price, and that c) promoting the social advancement of women would not have a significant effect despite incurring considerable social costs. We also extend our empirical model to a multinational-level data and show that some of the largest economies, such as China and Germany, would experience the aging of society in the next 30 years and those demographic changes will negatively impact on residential prices like Japan. This indicate that the findings of this study offer numerous suggestions not only for Japan but also for European and other Asian countries whose societies are expected to age at a greater rate in the future

三角線維軟骨複合体損傷における尺側手根伸筋腱と遠位橈尺関節のMRI画像分析

BACKGROUND: We compared the incidence of extensor carpi ulnaris (ECU) tendon and distal radioulnar joint (DRUJ) abnormalities using magnetic resonance imaging (MRI) between patients with triangular fibrocartilage complex (TFCC) tears and subjects without ulnar wrist pain. Additionally, we aimed to identify potential predictors of these MRI lesions. METHODS: The TFCC group comprised 70 consecutive patients with TFCC tears. The control group comprised 70 age- and sex-matched subjects without ulnar wrist pain. We evaluated the presence or absence of fluid collection in the DRUJ and ECU peritendinous area and longitudinal ECU tendon splitting. Dimensions of the fluid collection area around the ECU tendon were measured to evaluate the severity. The incidences of these abnormal MRI findings were compared between the two groups. We analyzed the correlation between the presence of ECU tendon and DRUJ lesions and variables including age, magnitude of ulnar variance, and type of TFCC tear. RESULTS: Significant differences were found between the two groups in the incidence of fluid collection of the DRUJ and ECU peritendinous area, and longitudinal ECU tendon splitting. Among the 70 patients with TFCC tears, age and the magnitude of ulnar variance were significantly correlated with the severity of fluid collection around the ECU tendon. The magnitude of ulnar variance in patients with DRUJ fluid collection was significantly larger than that in patients without fluid collection. There was a significant correlation between the presence of disc tears and DRUJ fluid collection. CONCLUSION: We found a higher incidence of accompanying abnormal MRI findings of the ECU tendon and DRUJ in patients with TFCC tears than in the control group. The presence of disc tears, the magnitude of ulnar variance, and age may be risk factors for these MRI lesions associated with TFCC tears.博士（医学）・甲第690号・平成30年11月30日Copyright © 2018 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved

三角線維軟骨複合体損傷における尺側手根伸筋腱と遠位橈尺関節のMRI画像分析

BACKGROUND: We compared the incidence of extensor carpi ulnaris (ECU) tendon and distal radioulnar joint (DRUJ) abnormalities using magnetic resonance imaging (MRI) between patients with triangular fibrocartilage complex (TFCC) tears and subjects without ulnar wrist pain. Additionally, we aimed to identify potential predictors of these MRI lesions. METHODS: The TFCC group comprised 70 consecutive patients with TFCC tears. The control group comprised 70 age- and sex-matched subjects without ulnar wrist pain. We evaluated the presence or absence of fluid collection in the DRUJ and ECU peritendinous area and longitudinal ECU tendon splitting. Dimensions of the fluid collection area around the ECU tendon were measured to evaluate the severity. The incidences of these abnormal MRI findings were compared between the two groups. We analyzed the correlation between the presence of ECU tendon and DRUJ lesions and variables including age, magnitude of ulnar variance, and type of TFCC tear. RESULTS: Significant differences were found between the two groups in the incidence of fluid collection of the DRUJ and ECU peritendinous area, and longitudinal ECU tendon splitting. Among the 70 patients with TFCC tears, age and the magnitude of ulnar variance were significantly correlated with the severity of fluid collection around the ECU tendon. The magnitude of ulnar variance in patients with DRUJ fluid collection was significantly larger than that in patients without fluid collection. There was a significant correlation between the presence of disc tears and DRUJ fluid collection. CONCLUSION: We found a higher incidence of accompanying abnormal MRI findings of the ECU tendon and DRUJ in patients with TFCC tears than in the control group. The presence of disc tears, the magnitude of ulnar variance, and age may be risk factors for these MRI lesions associated with TFCC tears.博士（医学）・甲第690号・平成30年11月30日Copyright © 2018 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved

指尖部再建術後における患者満足度とハンドパフォーマンスについての後ろ向き検討

Introduction: Hand performance tests that evaluate hand dexterity and use in daily living have been frequently used to evaluate outcomes in patients with various hand disorders but not in patients with fingertip injuries. The present study aimed to evaluate patient satisfaction and hand performance following digital artery flap reconstruction for fingertip injury and identify factors associated with these outcomes. Methods: This retrospective cohort study included 25 patients with amputation injuries at our institution between 2003 and 2013. Patients with amputations at the Tamai 1 or 2 zone of their index (14 patients) or middle finger (11 patients) who underwent digital artery flap surgery and were followed up for > 1 year were included. Follow-up evaluations were conducted at an average of 44 months postoperatively (range, 12–105 months). The primary outcomes were patient satisfaction and hand performance determined by a 4-grade Likert scale and the Purdue Pegboard test, respectively. Secondary outcomes were recovery of sensitivity measured by Semmes–Weinstein monofilaments, total active finger motion (TAM), and tip pinch strength. Results: There were no postoperative complications. Patient satisfaction was rated as fair, good, and excellent, in 1, 15, and 9 patients, respectively. The average hand performance test scores were significantly lower in the affected finger than the adjacent finger (22 vs. 30, respectively; p < 0.05). The mean ± standard deviation (SD) sensitivity test score was 3.5 ± 1.6 (range, 2.4–4.0). The average percentage TAM and tip pinch strength compared with the contralateral hand were 82 (range, 45–100%) and 82% (range, 60–112%), respectively. The hand performance score significantly correlated with the recovery of sensitivity and age (r = – 0.42 and 0.43, respectively; both p < 0.05). Patient satisfaction was significantly correlated with TAM (r = 0.42, p < 0.05) and tended to correlate with the recovery of sensitivity (r = – 0.395, p = 0.051). Conclusion: Although reconstructed fingers had a lower performance score than the adjacent fingers, patient satisfaction with flap surgery was relatively high. Recovery of finger sensitivity contributed to patient satisfaction and enhanced dexterity of motor skill activities following fingertip reconstruction.博士（医学）・乙第1410号・平成29年11月24日Copyright © 2017 by Thieme Medical Publishers, Inc.This journal is published under the Creative Commons license CC BY-NC-ND (Attribution-NonCommercial-NoDerivatives : https://creativecommons.org/licenses/by-nc-nd/4.0/)The definitive version is available at " http://dx.doi.org/10.1055/s-0037-1604157

尺骨偽関節に対する前骨間動脈を血管茎とした橈骨遠位からの有茎血管柄付き骨移植：解剖学的研究と症例報告

Background: A vascularized distal radius graft can be a reliable solution for the treatment of refractory ulnar nonunion. The aim of this study is to establish the anatomical basis of a vascularized bone graft pedicled by the anterior interosseous artery and report its clinical application, using cadaveric studies and a case report. Methods: Fourteen fresh frozen cadaveric upper limbs were used. The branches of the anterior interosseous artery (the 2, 3 intercompartmental supraretinacular artery and the fourth extensor compartment artery) were measured at the bifurcation site. The anatomical relationship between the anterior interosseous artery and motor branches of the posterior interosseous nerve was investigated. An anterior interosseous artery pedicled bone flap was used in a 48-year-old woman with refractory ulnar nonunion. Results: There were two variations depending on whether the 2,3 intercompartmental supraretinacular artery branched off distally or proximally from the terminal motor branch of the posterior interosseous nerve. The proximal border of the graft was located at an average of 10.5 cm (range, 6.5-12.5 cm) from the distal end of the ulnar head in the distal type (57%) and 17.5 cm (range, 9.5-21.5 cm) in the proximal type (43%). In the clinical application, successfully consolidation was achieved 4 months post-surgery. The patient had not developed any postoperative complications until the 2-year postoperative follow-up. Conclusions: The anterior interosseous artery-pedicled, vascularized distal radius bone graft would be a reliable alternative solution for the treatment of an ulnar nonunion located within the distal one-third of the ulna.博士（医学）・甲第767号・令和3年3月15日© 2020 Wiley Periodicals, Inc.This is the peer reviewed version of the following article: https://onlinelibrary.wiley.com/doi/full/10.1002/micr.30566, which has been published in final form at https://doi.org/10.1002/micr.30566. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions

肘の内外反変形に伴う尺骨神経の伸長度変化に関する生体力学的研究

Background: Cubital tunnel syndrome can be caused by overtraction and dynamic compression in elbow deformities. The extent to which elbow deformities contribute to ulnar nerve strain is unknown. Here, we investigated ulnar nerve strain caused by cubitus valgus/varus deformity using fresh-frozen cadavers. Methods: We used six fresh-frozen cadaver upper extremities. A strain gauge was placed on the ulnar nerve 2 cm proximal to the medial epicondyle of the humerus. For the elbow deformity model, osteotomy was performed at the distal humerus, and plate fixation was performed to create cubitus valgus/varus deformities (10°, 20°, and 30°). Ulnar nerve strain caused by elbow flexion (0–125°) was measured in both the normal and deformity models. The strains at different elbow flexion angles within each model were compared, and the strains at elbow extension and at maximum elbow flexion were compared between the normal model and each elbow deformity model. However, in the cubitus varus model, the ulnar nerve deflected more than the measurable range of the strain gauge; elbow flexion of 60° or more were considered effective values. Statistical analysis of the strain values was performed with Friedman test, followed by the Williams’ test (the Shirley‒Williams’ test for non-parametric analysis). Results: In all models, ulnar nerve strain increased significantly from elbow extension to maximal flexion (control: 13.2%; cubitus valgus 10°: 13.6%; cubitus valgus 20°: 13.5%; cubitus valgus 30°: 12.2%; cubitus varus 10°: 8.3%; cubitus varus 20°: 8.2%; cubitus varus 30°: 6.3%, P < 0.001). The control and cubitus valgus models had similar values, but the cubitus varus models revealed that this deformity caused ulnar nerve relaxation. Conclusions: Ulnar nerve strain significantly increased during elbow flexion. No significant increase in strain 2 cm proximal to the medial epicondyle was observed in the cubitus valgus model. Major changes may have been observed in the measurement behind the medial epicondyle. In the cubitus varus model, the ulnar nerve was relaxed during elbow extension, but this effect was reduced by elbow flexion.博士（医学）・甲第865号・令和5年3月15

骨形成細胞シートは血管柄付き人工骨内での骨形成および血管形成を促進させる

BACKGROUND: The regeneration of large, poorly vascularized bone defects remains a significant challenge. Although vascularized bone grafts promote osteogenesis, the required tissue harvesting causes problematic donor-site morbidity. Artificial bone substitutes are promising alternatives for regenerative medicine applications, but the incorporation of suitable cells and/or growth factors is necessary for their successful clinical application. The inclusion of vascular bundles can further enhance the bone-forming capability of bone substitutes by promoting tissue neovascularization. Little is known about how neovascularization occurs and how new bone extends within vascularized tissue-engineered bone, because no previous studies have used tissue-engineered bone to treat large, poorly vascularized defects. METHODS: In this study, the authors developed a novel vascularized tissue-engineered bone scaffold composed of osteogenic matrix cell sheets wrapped around vascular bundles within β-tricalcium phosphate ceramics. RESULTS: Four weeks after subcutaneous transplantation in rats, making use of the femoral vascular bundle, vascularized tissue-engineered bone demonstrated more angiogenesis and higher osteogenic potential than the controls. After vascularized tissue-engineered bone implantation, abundant vascularization and new bone formation were observed radially from the vascular bundle, with increased mRNA expression of alkaline phosphatase, bone morphogenetic protein-2, osteocalcin, and vascular endothelial growth factor-A. CONCLUSION: This novel method for preparing vascularized tissue-engineered bone scaffolds may promote the regeneration of large bone defects, particularly where vascularization has been compromised.博士（医学）・甲第652号・平成28年3月15日Copyright © 2016 American Society of Plastic Surgeons All rights reserved.This is a non-final version of an article published in final form in "http://dx.doi.org/10.1097/PRS.0000000000002079

橈骨頭単独脱臼に関する生体力学的研究

BACKGROUND: Isolated radial head dislocation is a rare injury with an unclear pathomechanism, and the treatment is controversial. The purpose of the present study was to investigate the biomechanical contributions of the annular ligament, quadrate ligament, interosseous membrane, and annular ligament reconstructions to proximal radioulnar joint stability. METHODS: Five fresh frozen cadaveric upper extremities were amputated above the elbow and solidly fixed on a customized jig. Radial head dislocation was reproduced by sequential sectioning of ligamentous structures and passive mobility testing. Radial head displacement during mobility testing was measured with an electromagnetic tracking device in three forearm rotation positions. The data were compared among different sectioning stages and between two types of simulated ligamentous reconstruction. RESULTS: Lateral displacement of the radial head significantly increased in the neutral forearm rotation after annular ligament sectioning (46 ± 10%, p < 0.05). After quadrate ligament sectioning, we found significant posterior (67 ± 36%, p < 0.05) and lateral (74 ± 24%, p < 0.01) displacement in neutral forearm rotation and pronation. Significant radial head displacement was found in all directions and in all forearm positions after sequential sectioning of the proximal half of the interosseous membrane. Anatomical annular ligament reconstruction stabilized the proximal radioulnar joint except for anterior laxity in neutral forearm rotation (15 ± 6%, p < 0.05). The radial head with Bell Tawse procedure was significantly displaced in all directions. CONCLUSION: The direction of radial head instability varied depending on the degree of soft tissue sectioning and specific forearm rotation. Anterior radial head dislocation may involve more severe ligament damage than other types of dislocation. Anatomical annular ligament reconstruction provided multidirectional radial head stability.博士（医学）・甲第683号・平成30年3月15日© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated

凍結保存骨形成細胞シートの骨再建における有用性

Skeletal diseases, such as nonunion and osteonecrosis, are now treatable with tissue engineering techniques. Single cell sheets called osteogenic matrix cell sheets (OMCSs) grown from cultured bone marrow-derived mesenchymal stem cells show high osteogenic potential; however, long preparation times currently limit their clinical application. Here, we report a cryopreservation OMCS transplantation method that shortens OMCS preparation time. Cryopreserved rat OMCSs were prepared using slow- and rapid-freezing methods, thawed, and subsequently injected scaffold-free into subcutaneous sites. Rapid- and slow-frozen OMCSs were also transplanted directly to the femur bone at sites of injury. Slow-freezing resulted in higher cell viability than rapid freezing, yet all two cryopreservation methods yielded OMCSs that survived and formed bone tissue. In the rapid- and slow-freezing groups, cortical gaps were repaired and bone continuity was observed within 6 weeks of OMCS transplantation. Moreover, while no significant difference was found in osteocalcin expression between the three experimental groups, the biomechanical strength of femurs treated with slow-frozen OMCSs was significantly greater than those of non-transplant at 6 weeks post-injury. Collectively, these data suggest that slow-frozen OMCSs have superior osteogenic potential and are better suited to produce a mineralized matrix and repair sites of bone injury.博士（医学）・甲第650号・平成28年3月15日Copyright © 2016 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0