Niki, Yasuo



School of Medicine, Department of Orthopaedic Surgery (Shinanomachi)


Associate Professor

E-mail Address

E-mail address

External Links

Career 【 Display / hide

  • 2003.10

    東京女子医科大学膠原病リウマチセンター, 整形外科, 講師


Research Areas 【 Display / hide

  • Orthopaedic surgery


Books 【 Display / hide

  • 今日の整形外科治療指針 第7版 segond骨折

    二木康夫, 2015

  • 今日の整形外科治療指針 第7版 脛骨粗面骨折

    二木康夫, 2015

  • 膝靭帯手術のすべて(越智光夫編) 前・後十字靭帯損傷に対する同時再建術

    二木康夫, 2013

  • 外来で診る関節痛(リウマチ)・整形外科疾患(竹内勤、千葉一裕編)関節リウマチの手術療法

    二木康夫, 2013

  • 外来で診る関節痛(リウマチ)・整形外科疾患(竹内勤、千葉一裕編)変形性膝関節症

    二木康夫, 2013

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Papers 【 Display / hide

  • What are the important manoeuvres for beginners to minimize surgical time in primary total knee arthroplasty?

    Niki Yasuo

    Knee Surg Sports Traumatol Arthrosc  2016

    Joint Work, Accepted

  • Self-flip Technique of the TightRope RT Button for Soft-Tissue Anterior Cruciate Ligament Reconstruction.

    Niki Yasuo

    Arthrosc. Tech.  2016

    Joint Work, Accepted

  • Effects of femoral bone tunnel characteristics on graft-bending angle in double-bundle anterior cruciate ligament reconstruction

    Niki Yasuo, Nagai Katsuya, Harato Kengo, Suda Yasunori, Nakamura Masaya, Matsumoto Morio

    Knee Surgery, Sports Traumatology, Arthroscopy  2015.08

    ISSN  0942-2056

     View Summary

    <p>Purpose: Bone tunnel creation techniques influence the 3-dimensional (3D) position of bone tunnels and graft-bending angle in anterior cruciate ligament (ACL) reconstruction. This study assessed graft-bending angle and 3D characteristics of femoral bone tunnels and compared them between outside-in (OI) and transportal (TP) techniques. Methods: Participants comprised 64 patients who underwent anatomic double-bundle ACL reconstruction, allocated to OI and TP groups (n = 32 each). The graft orientation plane exhibiting the largest graft-bending angle at the femoral tunnel aperture with the knee in extension was reconstructed from CT data using 3D imaging software. In this plane, graft-bending angle was compared between the OI and TP techniques. Results: Although positionings of the intra-articular apertures of the femoral and tibial bone tunnels were similar, several spatial parameters of bone tunnels differed between techniques. Graft-bending angles of both anteromedial and posterolateral bundles were significantly more acute with the OI technique than with the TP technique. On coronal-plane CT, angle of the bone tunnel axis relative to the distal condylar axis correlated negatively with graft-bending angle, while in the axial plane, angle of the bone tunnel axis relative to the posterior condylar axis correlated positively with graft-bending angle. Lysholm score, pivot shift test, and anteroposterior laxity at &gt;2.5-year follow-up demonstrated no significant differences between techniques. Discussion: Different bone tunnel directions in OI and TP techniques substantially affected graft-bending angle, despite similar positionings of the intra-articular apertures. Graft-bending angle with the OI technique was acute, but risk of posterior blowout of the lateral femoral condyle was decreased. Surgeons should create the femoral tunnel while considering an obtuse graft-bending angle without increasing the risk of posterior blowout. Level of evidence: III.</p>

  • Factors affecting the achievement of Japanese-style deep knee flexion after total knee arthroplasty using posterior-stabilized prosthesis with high-flex knee design

    Niki Yasuo, Takeda Yuki, Harato Kengo, Suda Yasunori

    Journal of Orthopaedic Science  2015.08

    ISSN  0949-2658

     View Summary

    <p>Background: Achievement of very deep knee flexion after total knee arthroplasty (TKA) can play a critical role in the satisfaction of patients who demand a floor-sitting lifestyle and engage in high-flexion daily activities (e.g., seiza-sitting). Seiza-sitting is characterized by the knees flexed &gt;145º and feet turned sole upwards underneath the buttocks with the tibia internally rotated. The present study investigated factors affecting the achievement of seiza-sitting after TKA using posterior-stabilized total knee prosthesis with high-flex knee design. Methods: Subjects comprised 32 patients who underwent TKA with high-flex knee prosthesis and achieved seiza-sitting (knee flexion &gt;145º) postoperatively. Another 32 patients served as controls who were capable of knee flexion &gt;145º preoperatively, but failed to achieve seiza-sitting postoperatively. Accuracy of femoral and tibial component positions was assessed in terms of deviation from the ideal position using a two-dimensional to three-dimensional matching technique. Accuracies of the component position, posterior condylar offset ratio and intraoperative gap length were compared between the two groups. Results: The proportion of patients with &gt;3º internally rotated tibial component was significantly higher in patients who failed at seiza-sitting (41 %) than among patients who achieved it (13 %, p = 0.021). Comparison of intraoperative gap length between patient groups revealed that gap length at 135º flexion was significantly larger in patients who achieved seiza-sitting (4.2 ± 0.4 mm) than in patients who failed at it (2.7 ± 0.4 mm, p = 0.007). Conversely, no significant differences in gap inclination were seen between the groups. Conclusions: From the perspective of surgical factors, accurate implant positioning, particularly rotational alignment of the tibial component, and maintenance of a sufficient joint gap at 135º flexion appear to represent critical factors for achieving &gt;145º of deep knee flexion after TKA.</p>

  • Methotrexate inhibits osteoclastogenesis by decreasing RANKL-induced calcium influx into osteoclast progenitors

    Kanagawa Hiroya, Masuyama Ritsuko, Morita Mayu, Sato Yuiko, Niki Yasuo, Kobayashi Tami, Katsuyama Eri, Fujie Atsuhiro, Hao Wu, Tando Toshimi, Watanabe Ryuichi, Miyamoto Kana, Morioka Hideo, Matsumoto Morio, Toyama Yoshiaki, Saya Hideyuki, Miyamoto Takeshi

    Journal of Bone and Mineral Metabolism  2015.07

    ISSN  0914-8779

     View Summary

    <p>The increasing number of osteoporosis patients is a pressing issue worldwide. Osteoporosis frequently causes fragility fractures, limiting activities of daily life and increasing mortality. Many osteoporosis patients take numerous medicines due to other health issues; thus, it would be preferable if a single medicine could ameliorate osteoporosis and other conditions. Here, we screened 96 randomly selected drugs targeting various diseases for their ability to inhibit differentiation of osteoclasts, which play a pivotal role in development of osteoporosis, and identified methotrexate (MTX), as a potential inhibitor. MTX is currently used to treat sarcomas or leukemic malignancies or auto-inflammatory diseases such as rheumatoid arthritis (RA) through its anti-proliferative and immunosuppressive activities; however, a direct effect on osteoclast differentiation has not been shown. Here, we report that osteoclast formation and expression of osteoclastic genes such as NFATc1 and DC-STAMP, which are induced by the cytokine RANKL, are significantly inhibited by MTX. We found that RANKL-dependent calcium (Ca) influx into osteoclast progenitors was significantly inhibited by MTX. RA patients often develop osteoporosis, and osteoclasts are reportedly required for joint destruction; thus, MTX treatment could have a beneficial effect on RA patients exhibiting high osteoclast activity by preventing both osteoporosis and joint destruction.</p>

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Papers, etc., Registered in KOARA 【 Display / hide

Presentations 【 Display / hide

  • Effect of Unstable Meniscal Injury on Three-dimensional Knee Kinematics in ACL-deficient Patients During Gait

    Harato K,Niki Y,Sakurai A,Kudo Y,Nagura T,Masumoto K,Otani T,Toyama Y,Suda Y

    Orthopaedic Research Society (ORS), 2015

  • MRIによる再建靭帯評価


    膝関節フォーラム, 2015

  • シンポジウム4 TKA手術手技 アナトミックアライメントTKAの手術手技


    日本人工関節学会, 2015

  • 解剖学的アライメントの再現を目指したTKA術前プランニング(関節面基準とcylindrical axis基準との比較検討)


    日本人工関節学会, 2015

  • キネマティックアライメントによるTKAでは膝内反モーメントが増大するか?


    日本人工関節学会, 2015

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Research Projects of Competitive Funds, etc. 【 Display / hide

  • 力学的負荷誘発性in vitro OA modelの確立と関節破壊様式の解析


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 二木 康夫, Grant-in-Aid for Scientific Research (C), Principal Investigator

  • IL-1 and TLR signals play an important role in mechanical stress-induced osteoarthritis


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 二木 康夫, Grant-in-Aid for Scientific Research (C), Principal Investigator

Awards 【 Display / hide

  • 慶應義塾大学医学部三四会北島賞

    2017.06, 慶應義塾大学医学部三四会

  • 慶應義塾大学医学部三四会奨励賞

    2001, 慶應義塾大学医学部三四会


Courses Taught 【 Display / hide