A Finite Element Model of a Rotating Platform Total Knee Employing a Nonlinear, Dual-Surface-Contact Formulation

Mapping Intimacies ◽

10.1115/imece2000-2582 ◽

2000 ◽

Author(s):

Jason K. Otto ◽

Thomas D. Brown ◽

John J. Callaghan

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Mobile Bearing ◽

Element Model ◽

Polyethylene Insert ◽

Rotating Platform ◽

Mobile Interface ◽

Surface Contact ◽

Total Knee

Abstract Mobile bearing total knees avoid the conformity/constraint tradeoff of fixed bearing total knees. However, a recent in vivo fluoroscopic study of the most popular mobile bearing total knee in the U.S. showed that bearing motion failed to occur in half of the patients observed. A nonlinear, multiple-surface contact finite element model of a rotating platform total knee was therefore developed to investigate the interaction at the “mobile” interface (contact between the tibial tray and the polyethylene insert) under physiologically relevant loads (1–4 BW) and rotations (10° endorotation). The data showed that there was a linear relationship between axial load and the torque resisting endorotation. Peak contact stresses were located on the medial and lateral peripheral edges of the polyethylene insert. All relative rotation occurred at the “mobile” interface. The same trends were seen in a complementary experimental study of the same components, suggesting that the finite element model is valid under these loading conditions.

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Differences in Anatomy and Kinematics in Asian and Caucasian TKA Patients: Influence on Implant Positioning and Subsequent Loading Conditions in Mobile Bearing Knees

BioMed Research International ◽

10.1155/2014/612838 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 6

Author(s):

Allan Maas ◽

Tae Kyun Kim ◽

Rolf K. Miehlke ◽

Thomas Hagen ◽

Thomas M. Grupp

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Knee Flexion ◽

Failure Modes ◽

Mobile Bearing ◽

Element Model ◽

Floating Platform ◽

Implant Positioning ◽

Roll Back

The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee kinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates the seldom but severe complication of fatigue failure of polyethylene components at mobile bearing total knee arthroplasty designs. Assuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian countries we developed a simplified finite element model considering a tibiofemoral roll-back angle of 22° and the range of rotational motion of a clinically established floating platform design (e.motion FP) at a knee flexion angle of 120° in order to compare our results to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations of the occurring stress maxima as well as the tensile stress distribution show analogies. From our observations, we conclude that the newly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated tibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure modes.

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Using Musculoskeletal Models to Estimate in vivo Total Knee Replacement Kinematics and Loads: Effect of Differences Between Models

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.703508 ◽

2021 ◽

Vol 9 ◽

Author(s):

Cristina Curreli ◽

Francesca Di Puccio ◽

Giorgio Davico ◽

Luca Modenese ◽

Marco Viceconti

Keyword(s):

Finite Element ◽

Knee Joint ◽

Total Knee Replacement ◽

Finite Element Model ◽

Knee Replacement ◽

Element Model ◽

Assessment Process ◽

Grand Challenge ◽

Total Knee

Total knee replacement (TKR) is one of the most performed orthopedic surgeries to treat knee joint diseases in the elderly population. Although the survivorship of knee implants may extend beyond two decades, the poor outcome rate remains considerable. A recent computational approach used to better understand failure modes and improve TKR outcomes is based on the combination of musculoskeletal (MSK) and finite element models. This combined multiscale modeling approach is a promising strategy in the field of computational biomechanics; however, some critical aspects need to be investigated. In particular, the identification and quantification of the uncertainties related to the boundary conditions used as inputs to the finite element model due to a different definition of the MSK model are crucial. Therefore, the aim of this study is to investigate this problem, which is relevant for the model credibility assessment process. Three different generic MSK models available in the OpenSim platform were used to simulate gait, based on the experimental data from the fifth edition of the “Grand Challenge Competitions to Predict in vivo Knee Loads.” The outputs of the MSK analyses were compared in terms of relative kinematics of the knee implant components and joint reaction (JR) forces and moments acting on the tibial insert. Additionally, the estimated knee JRs were compared with those measured by the instrumented knee implant so that the “global goodness of fit” was quantified for each model. Our results indicated that the different kinematic definitions of the knee joint and the muscle model implemented in the different MSK models influenced both the motion and the load history of the artificial joint. This study demonstrates the importance of examining the influence of the model assumptions on the output results and represents the first step for future studies that will investigate how the uncertainties in the MSK models propagate on disease-specific finite element model results.

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