Stress Analysis of the Anterior Tibial Post in Posterior Stabilized Knee Prostheses
Resource
JOURNAL OF ORTHOPAEDIC RESEARCH v.25 n.4 pp.442-449
Journal
JOURNAL OF ORTHOPAEDIC RESEARCH
Journal Volume
v.25
Journal Issue
n.4
Pages
442-449
Date Issued
2007
Date
2007
Author(s)
HUANG, CHANG-HUNG
LIAU, JIANN-JONG
HUANG, CHUN-HSIUNG
CHENG, CHENG-KUNG
Abstract
Recent retrieval studies have indicated a high incidence of polyethylene wear on the anterior tibial post caused by impingement. This study investigated the influences of post- cam design features and component alignment on the stress distribution in the anterior tibial post when subjected to the impingement loading. Two three-dimensional finite element models of posterior stabilized knee prostheses were constructed, one with flat on flat (FF) and another with curve on curve (CC) contact surfaces between anterior tibial post and femoral cam. The polyethylene insert was modeled with elastoplastic properties. Nine cases, three hyperextension angles (0 degrees, 5 degrees, and 10 degrees) combined with three axial tibial rotations (0 degrees, 2.5 degrees, and 5 degrees) simulating different component alignments were analyzed. A vertical compressive load of 2, 000 N and an extension moment of 45 Nm were applied simultaneously. The FF model had larger stress increases than the CC model in both hyperextension and tibial rotation compared with the neutral position. The maximum increase for the FF model was 68% in peak contact stress, 125% in von Mises stress, and 58% in tensile stress in the extreme case of 10 degrees of hyperextension combined with 5 degrees of axial rotation. Stress concentration was found at the anterior corner of the post in the FF model; this was not found in the CC model. The curve on curve design can reduce edge loading on the tibial post, especially during axial tibiofemoral rotation. (c) 2007 Orthopaedic Research Society . Published by Wiley Periodicals, Inc.
Subjects
anterior impingement
tibial post
posterior stabilized
post- cam mechanism
finite element analysis