• Title/Summary/Keyword: tendon stress at failure

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Posterior Cruciate Ligament and Posterolateral Structure Reconstruction using Bilateral Hamstring Tendons (양측 슬괵건을 이용한 후방 십자 인대 및 후외측 지대 재건술)

  • In, Yong;Kim, Seok-Jung;Lee, Gyu-Yeong
    • Journal of the Korean Arthroscopy Society
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    • v.9 no.2
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    • pp.167-173
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    • 2005
  • Purpose: The purpose of this study is to evaluate the clinical results of posterior cruciate ligament (PCL) and posterolateral structure (PLS) reconstruction using bilateral hamstring tendon autografts. Materials and Methods: From October 2002 to March 2004, ten patients were received PCL and PLS reconstruction simultaneously using bilateral hamstring autografts. PCL was reconstructed using ipsilateral hamstring tendon and fixed with cross pins and Intrafix (Mitek, Norwood, MA). PLS was reconstructed using contralateral hamstring tendon. The mean follow up was 17 months. Clinical assessments consisted of Lysholm knee scores, International Knee Documentation Committee (IKDC) evaluation form and posterior stress radiographs. External rotation of tibia was evaluated at $30^{\circ}\;and\;90^{\circ}$ knee flexion using Noyes and Barber-Westin's classification. Contralateral harvest site morbity was evaluated using IKDC evaluation form and flexion power of the knee. Results: Mean posterior displacement of tibia using stress radiographs was improved from 13.3 mm to 3.7 mm. In tibial external rotation evaluation, 7 patients were functional, 2 patients were partially functional and one failure. The average Lysholm knee score improved from 54 preoperatively to 86 postoperatively. At the final IKDC evaluation, 8 patients were graded as nearly normal, 2 were graded as abnormal. In contralateral harvest site morbidity evaluation, 2 patients complained of numbness around the wound but negligible. Conclusion: PCL and PLS reconstruction using bilateral hamstring autografts was considered as a good treatment method with minimal contralateral harvest site morbidity.

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Investigation on Applicability of 2400 MPa Strand for Posttensioned Prestressed Concrete Girders (포스트텐션 PSC 거더에 대한 2400 MPa급 강연선의 적용성 분석)

  • Park, Ho;Cho, Jae-Yeol;Kim, Jee-Sang
    • Journal of the Korea Concrete Institute
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    • v.24 no.6
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    • pp.727-735
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    • 2012
  • Recently, a high-strength strand of 2400 MPa was developed using domestic technologies. In 2011, KS D 7002 was revised to cover the newly developed high-strength strands to support their practical usage. Presently, however, discussions and evaluations are not sufficient on the mechanical properties of the strands and their performance in structural members. Also, there were no detailed reviews on the need to revise the current design code for practical use of the high-strength strands. In this study, flexural behavior of a member with the high-strength strands was estimated through sectional analysis and a review and comparison of the domestic and foreign design codes were conducted considering the analysis results. Also, the need for the revision of the design code was discussed. Such discussion especially focused on the estimation of the stress in strand, which related with various issues such as determination methods for yield point of strands, time-dependent loss of prestressing force, estimation of stress in strand at member failure, and net strain limit for ductile failure of member. The discussion revealed that some parts in the design code need a revision and the further studies are required.