Artificial Anterior Cruciate Ligament (ACL) Reconstruction for more Natural Knee Kinematics

Mona Alinejad, Elise Pegg, Christopher, A. F. Dodd, JJ O'Connor, David Murray

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The aims of this study were to define the design criteria of an artificial ACL which could reproduce the non-linear load-elongation characteristics of the native ACL, and to investigate the mechanical behaviour of a novel ACL reconstruction design consisting of a metallic elastic system and a polymeric cord.
Kinematic and survivorship studies on the ACL intact and ACL deficient knees have emphasised the importance of preserving and/or reconstructing the ACL [1], [2]. The unique mechanical properties of the ACL and the non-linear relationship between the ACL forces and the quadriceps muscle forces at different flexion angles are the key elements in providing normal kinematics.
Current synthetic ACL reconstruction grafts have shown poor long-term results, mainly due to wear, creep, fatigue and mechanical failure. None of the synthetic and biological grafts used for the ACL reconstruction have been able to replicate the normal mechanical behaviour of the ACL and prevent degenerative disease progression such as osteoarthritis.
Desired mechanical properties of the artificial ACL were defined based the results of in vitro and in vivo biomechanical studies. Suitable materials were found for the prosthetic ACL which met the required design criteria. Implicit finite element analyses were performed on a spring-cord construct design and the output force-elongation data compared to the estimated in-vivo natural ACL properties found in the literature.
It was shown that an artificial ACL should have a non-linear stiffness with low resistance to the initial load (~30 Nmm-1 stiffness in the toe region) and increased stiffness under higher load (~110 Nmm-1 stiffness in the linear region). Suitable materials for the ACL reconstruction design (i.e. CoCrMo alloy and UHMWPE fibres) were identified based on their biocompatibility, strength, strain, creep and fatigue properties
The FEA results showed that the mechanical properties of the novel artificial ACL deisgn closely resembled that of the natural ACL at 30° of flexion. A validation test was performed on prototype samples, which supported the finite element data.
The non-linear force-elongation properties of the native ACL can be reproduced by an artificial ACL reconstruction system in the ACLD knees.
Original languageEnglish
Publication statusPublished - Aug 2013
Event4th Joint Meeting of the Bone Research Society & the British Orthopaedic Research Society - Oxford, UK United Kingdom
Duration: 4 Sept 20135 Sept 2013


Conference4th Joint Meeting of the Bone Research Society & the British Orthopaedic Research Society
Country/TerritoryUK United Kingdom


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