Optimization of ligament parameters on a subject-specific computational human knee model in a dynamic knee simulator using design of experiments
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The objective of this study was to optimize ligament parameters used in a dynamic three dimensional subject-specific computational knee model. The parameters of interest are the zero load length (lambda sub zero), stiffness (k) and the strain level where the force length relationship of the ligament goes from the nonlinear "toe" region to the linear region (epsilon sub l). Experimental testing was performed at the University of Kansas Experimental Joint Biomechanics Research Laboratory (Lawrence, Kansas) in the Kansas Knee Simulator (KKS) under various loading profiles while the kinematics of the knee was recorded. A model of the knee in the KKS was created using previously validated modeling techniques. The experimental and model simulation kinematics for a ten second walk cycle were compared in a two level partial factorial design and a three level full factorial design and the ligament parameters were optimized based on the kinematic RMS error. The resulting parameter values are 80% of the experimentally derived zero load length values, 99.71% of the published ligament stiffness values, and 100% of the published epsilon sub l. These values are reasonable, and are validated by the stiffness values from the optimization closely matching published values for each ligament's stiffness.
Table of Contents
Introduction -- Literature review of computational knee model ligaments and their parameters -- Materials and methods -- Results -- Conclusion -- Discussion -- Appendix