Papers by Keyword: Anterior Cruciate Ligament

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Authors: Markos Petousis, Achilles Vairis, Betina Kandyla, George Stefanoudakis, Nektarios Vidakis
Abstract: The anterior cruciate ligament in the knee connects the femur to the tibia and is often torn during a sudden twisting motion, resulting in knee instability. Effective treatment is with surgery where the ligament is replaced with a piece of healthy tendon grafted into place to hold the knee joint together. Employing a novel repair device, models for the repaired and for the intact knee are developed to evaluate the efficacy of the design the device.
Authors: A.H. Alafiah, M. Normahira, M.N. Anas
Abstract: Anterior Cruciate Ligament (ACL) is of the major knee ligament. A three dimensional model that reflects the geometric characteristics of the human ACL developed to explore and analyze finite element parameters such as contact pressure and stress distribution on ACL in response to complex loading conditions. Moreover, various cases studied such as cases involving and uninvolving ligament in order to obtain and analyze the stress and contact pressure relationship between ACL, meniscus and cartilage. It is known that the contact and friction caused by the ACL wrapping around the bone during knee motion played the role of transferring the force from the ACL to the bone, and had a direct effect on the stress distribution of the ACL. Thus, the project lead to better understand the mechanism of injury, to improve the design of ACL reconstruction using suitable material and optimizing rehabilitation protocols by investigation of contact pressure with and without ACL.
Authors: Na Li, Song Wu, Wei Wang, Bin Ye
Abstract: ACL damage is one the most frequent causes of knee injuries and thus has long been the focus of research in biomechanics and sports medicine. Due to the anisometric geometry and functional complexity of the ACL in the knee joint, it is usually difficult to experimentally study the biomechanics of ACLs. Anatomically ACL geometry was obtained from both MR images and anatomical observations. The optimal material parameters of the ACL were obtained by using an optimization-based material identification method that minimized the differences between experimental results from ACL specimens and FE simulations. The optimal FE model simulated biomechanical responses of the ACL during complex combined injury-causing knee movements, it predicted stress concentrations on the top and middle side of the posterolateral (PL) bundles. This model was further validated by a clinical case of ACL injury diagnosed by MRI and arthroscope, it demonstrated that the locations of rupture in the patients knee corresponded to those where the stresses and moments were predicted to be concentrated. The result implies that varus rotation played a contributing but secondary role in injury under combined movements, the ACL elevation angle, is positive correlated with the tensional loading tolerance of the ACL.
Authors: Rong Ying Huang, Hong Guang Zheng, Qiang Xu
Abstract: Anterior cruciate ligament injuries commonly in traffic accident, sports activities and extreme sports. Anterior cruciate ligament reconstruction is a common practice to help the patients restore the knee stability. However, there is no previous comparison study of single bundle reconstruction, double-femoral double-tibial tunnel reconstruction, single-femoral double-tibial tunnel reconstruction, and double-femoral single-tibial tunnel reconstruction with respect to biomechanical characteristics such as rotational stability, force and stress inside the ligament and grafts, stresses inside the soft tissues. In this study, we developed a pair of three-dimensional finite element models of a lower extremity including femur, tibia, fibula, cartilage, meniscus, and four major ligaments at 0°,25°,60° and 80°of knee flexion. Based on the intact models, single bundle reconstruction, double-femoral double-tibial tunnel reconstruction, single-femoral double-tibial tunnel reconstruction, and double-femoral single-tibial tunnel reconstruction models were also developed. Then, the anterior tibial translations, the forces and stresses inside the ACL and ACL replacements, as well as the stresses inside the menisci, femoral and tibial cartilage were predicted under a combined rotatory load of 10Nm valgus moment and 5 Nm internal torque, respectively using finite element analysis. The rotational stability, ligament forces and stresses in the menisci, femoral and tibial cartilage following double bundle augmentation were superior to the other reconstruction techniques, while there is little advantage in ligament stress compared to that of the single bundle reconstruction. We conclude that double-femoral double-tibial tunnel reconstruction may have advantages with regard to biomechanical characteristics such as rotational stability, force inside the ligament and grafts, stresses inside the soft tissues.
Authors: Shinobu Kobayashi, Masataka Sakane, Hirotaka Mutsuzaki, Hiromi Nakajima, M. Tanaka, Yutaka Miyanaga, Naoyuki Ochiai
Abstract: We hybridized calcium phosphate (CaP) with human semitendinosus and gracilis (ST/G) tendon grafts using an alternate soaking process. To evaluate quantitatively and histologically assess the CaP hybridized human ST/G tendon grafts, we classified them into three groups according to their soaking time – number of soaking cycle: 30 sec – 20 cycles (Group A), 1 min – 15 cycles (Group B), 3 min – 5 cycles (Group C). The tendon grafts were divided into three parts: tibial end (TE), femoral end (FE) and intra-articular (IA) portion. TE was secured using the Krackow technique with No. 2 nonabsorbable sutures, and an Endobutton-CL (Smith & Nephew, USA) was passed through the looped FE, as performed clinically. Then, the IA portion was covered with the sleeve of a rubber glove to prevent CaP hybridization. More soaking cycles induced greater deposition of CaP in the tendon grafts when the total soaking time was the same. Covering the IA portion with a rubber sleeve prevented of CaP deposition. A large amount of CaP in TE was deposited because suture holes increased the total contact area with the solutions.
Authors: Hirotaka Mutsuzaki, Masataka Sakane, Yumi Katayoshi, Sinya Hattori, Hiromi Nakajima, M. Tanaka, Naoyuki Ochiai
Abstract: Calcium phosphate (CaP) hybridized to a whole tendon graft delayed cell repopulation in anterior cruciate ligament (ACL) reconstruction in rabbits. However, a tendon graft masked with an adhesive tape at the intra-articular (IA) portion to prevent CaP hybridization did not delay cell repopulation. Synovial tissues can adhere to the tendon graft and can invade the tendon graft masked at the IA portion. The masking induced an effect similar to that of the unhybridized tendon graft. The CaP hybridized tendon grafts masked at the IA portion showed cell repopulation 2 weeks earlier than the unmasked CaP hybridized tendon grafts.
Authors: Sandeep Liyanage, Philip Boughton, G. Roger, Jari Hyvarinen, Andrew Ruys
Abstract: Review of current Anterior Cruciate Ligament (ACL) anchor technologies indicates that many devices facilitate osteointegration but not soft tissue in-growth. The design and preliminary testing of a novel biomimetic in-situ dilating bioabsorbable ACL anchor for simultaneous soft and hard tissue attachment is the subject of this study. The anchor method for this concept has been developed to mimic the mechanical-key configuration observed in a hair root. Reviewed anchor devices are typically interference screw-based. Screw anchors can lead to unnecessary ligament pre-stress, tearing during deployment and poor graft-bone contact. This work demonstrates a new fixation concept specifically developed for use with devices consisting of temperature-sensitive glass-reinforced-glass (GRG) soft tissue conductive biomaterial. Ligament anchorage is accomplished by dilation of the device into the base of a hair-root shaped osteotomy where a ligament with a collar and self tightening knot is inserted beforehand. This method facilitates full ligament-to-bone contact at the osteotomy zone where critical physiological ligament anchorage develops. Ligament pull-out loads equivalent to published results for conventional anchors were achieved using graft analogue. Testing with porcine ligaments resulted in a substantial reduction in ligament pull-out loads. Tibia bone sample constraints combined with the unraveling of the ligament knot were identified as primary factors for low pull-out loads for the porcine ligament tests. Subsequent design iterations will employ a reduction in prototype dimensions in addition to the use of a suture to lock the ligament knot. The hair-root shaped osteotomy and ligament anchor knot elements of this approach may be translated to other fixation systems and methods. By improving macro-mechanical-key interaction between the anchor, bone and ligament, further increase in pull-out forces may be achieved without unnecessary ligament pre-stress and tear damage caused by conventional interference screw threads.
Authors: Yan Hu, Jun Wei, Lei Li, Shi Li, Xi Ju Zong
Abstract: Aiming at the problems of the anterior cruciate ligament (ACL) reconstruction in knee joint, such as deficiency in effective effect evaluation and insufficiency in operation safety, a zero gravity based force-measuring robot is developed to measure the pre- and post-operative tension of the knee joint ACL. The requirements for the robot's configuration and control are analyzed with regard to the ACL operation environment. Then the mathematical model of the ACL lateral force is deduced. The mechanical configuration and the control system design of the force-measuring robot for knee joint ACL are presented in detail. Lastly, experiments on measuring precision of the displacement and force of the mandrel, and the post-operation evaluation on the ovine bone, are implemented. The results show that the robot is effective for ACL reconstruction evaluation and the mathematics model of ACL forced in lateral direction is valid.
Authors: Jing Ling Zhang, Lin Guo, Long Chen, Shuai Hua Li, Gang Wu
Abstract: Here we report the development of Poly Urethane (PU)/ graphene oxide composite used as the scaffold of anterior cruciate ligament tissue engineering. The influences of the GO on the composite were studied by FTIR, SEM and XRD. The Youngs modulus of the composite is 30.6 MPa compared to that of PU`s 6.8 MPa. The GO induced heterogeneous crystal increasing should be the reason for the composite modulus improving, as well as the interaction between the GO and PU. The good biocompatibility of the composite testified by cell viability experiment indicates the promising candidates of the material as the ACL tissue engineering scaffold.
Authors: Byung Young Moon, H. K. Kang, Kwon Son, S.W. Chung
Abstract: Anterior cruciate ligament(ACL) is liable to a major injury that often results in a functional impairment requiring surgical reconstruction. The success of reconstruction depends on such factors as attachment positions, initial tension of ligament and surgical methods of fixation. The purpose of this study is to find isometric positions of the substitute during flexion/extension. A threedimensional knee model was constructed from CT images and was used to simulate length change during knee flexion/extension. The results showed that minimum length changes were 1.9~5.8 mm(average 3.6±1.4 mm). The proposed method can be utilized and applied to optimal reconstruction for ACL deficient knee.
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