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BioMed Research International
Volume 2014, Article ID 612838, 10 pages
http://dx.doi.org/10.1155/2014/612838
Research Article

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

1Aesculap AG Research & Development, Am Aesculap-Platz, 78532 Tuttlingen, Germany
2Joint Reconstruction Center, Seoul National University Bundang Hospital, Seongnam 463-707, Republic of Korea
3Knee Division, The Rhine-Main Centre for Joint Diseases, Wilhelmstraße 30, 65183 Wiesbaden, Germany
4Knee Division, The Muensterland Centre for Joint Diseases, Buelt 13, 48143 Muenster, Germany
5Ludwig Maximilians University Clinic for Orthopaedic Surgery, Campus Grosshadern, Marchioninistraße 15, 81377 Munich, Germany

Received 18 June 2014; Revised 30 July 2014; Accepted 30 July 2014; Published 20 November 2014

Academic Editor: Sandra Utzschneider

Copyright © 2014 Allan Maas et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.