The influence of ligament modelling strategies on the predictive capability of finite element models of the human knee joint

• Published in: Journal of biomechanics Vol. 65; pp. 1 - 11
• Main Authors: Naghibi Beidokhti, Hamid, Janssen, Dennis, van de Groes, Sebastiaan, Hazrati, Javad, Van den Boogaard, Ton, Verdonschot, Nico
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 08.12.2017; Elsevier Limited
• Subjects: Biomechanical Phenomena; Biomechanics; Collagen; Computational model validation; Contact pressure; Continuum modeling; Finite Element Analysis; Finite element method; Human performance; Humans; Kinematics; Knee; Knee contact pressure; Knee Joint - physiology; Knee ligament; Ligaments; Ligaments, Articular - physiology; Mathematical models; Mechanical properties; Modelling; Models, Biological; Predictions; Representations; Sensors; Springs; Stiffness; Subject-specific model; Three dimensional models; Finite element method; Knee contact pressure; Subject-specific model; Knee ligament; Kinematics; Computational model validation
• ISSN: 0021-9290; 1873-2380; 1873-2380
• DOI: 10.1016/j.jbiomech.2017.08.030

In finite element (FE) models knee ligaments can represented either by a group of one-dimensional springs, or by three-dimensional continuum elements based on segmentations. Continuum models closer approximate the anatomy, and facilitate ligament wrapping, while spring models are computationally less expensive. The mechanical properties of ligaments can be based on literature, or adjusted specifically for the subject. In the current study we investigated the effect of ligament modelling strategy on the predictive capability of FE models of the human knee joint. The effect of literature-based versus specimen-specific optimized material parameters was evaluated. Experiments were performed on three human cadaver knees, which were modelled in FE models with ligaments represented either using springs, or using continuum representations. In spring representation collateral ligaments were each modelled with three and cruciate ligaments with two single-element bundles. Stiffness parameters and pre-strains were optimized based on laxity tests for both approaches. Validation experiments were conducted to evaluate the outcomes of the FE models. Models (both spring and continuum) with subject-specific properties improved the predicted kinematics and contact outcome parameters. Models incorporating literature-based parameters, and particularly the spring models (with the representations implemented in this study), led to relatively high errors in kinematics and contact pressures. Using a continuum modelling approach resulted in more accurate contact outcome variables than the spring representation with two (cruciate ligaments) and three (collateral ligaments) single-element-bundle representations. However, when the prediction of joint kinematics is of main interest, spring ligament models provide a faster option with acceptable outcome.