Ligament Property Optimization Within a Virtual Biomechanical Knee

Abstract

Specimen-specific modeling of the knee can be an effective tool for understanding knee mechanics [1–2]. It can also serve as a design tool for orthopaedic implant design through enhancing understanding of mechanics in the reconstructed knee [3], particularly when used in conjunction with instrumented components that record in vivo joint forces [4]. Techniques for developing specimen-specific computational geometric models of hard tissue and soft tissue are fairly commonplace, using imaging tools such as computed tomography (CT) and magnetic resonance (MR) in conjunction with software tools for image processing. Determination of specimen-specific material properties relies on measuring kinematics of the tissue associated with a defined load, either in vivo or in vitro, selecting an appropriate material model, and estimating values of the parameters of the model that closely match the experimental data. The goal of this work was to utilize inverse finite element (FE) analysis to determine material parameters of ligaments in a specimen-specific model of the knee, using both local and global optimization algorithms.

Peak stresses shift from femoral tunnel aperture to tibial tunnel aperture in lateral tibial tunnel ACL reconstructions: a 3D graft-bending angle measurement and finite-element analysis

“…These techniques allow for very precise tunnel placement at the level of the native femoral ACL footprint as desired in anatomic ACL surgery. Furthermore, the position of the cortical exit point of the pin on the lateral side can be modified allowing for free femoral tunnel orientation1 [43, 47, 49].…”

“…7 Peak stresses gained in the ACL graft for medial and lateral tibial tunnels with different drill-guide angles. Note that the peak stresses are seen at the level of the tibial tunnel aperture in a lateral tibial tunnel and at the level of the femoral tunnel aperture when a medial tibial tunnel is used be modified allowing for free femoral tunnel orientation1 [43,47,49]. Therefore, retrograde tunnel drilling in anatomic ACL reconstruction will allow for a better positioning of the femoral tunnel, more in line with the intra-articular part of the ACL graft.…”

“…The tibia and femur were modelled as rigid bodies, because their high stiffness compared to the tendons. For the ACL graft, a linear elastic, anisotropic orthotropic model was used [43].…”