Forschungsdatenbank PMU-SQQUID

PMU-Autor/inn/en

Abstract

The study focused on the influence of the implant material stiffness on stress distribution and micromotion at the interface of bone defect implants. We hypothesized that a low-stiffness implant with a modulus closer to that of the surrounding trabecular bone would yield a more homogeneous stress distribution and less micromotion at the interface with the bony bed. To prove this hypothesis we generated a three-dimensional, non-linear, anisotropic finite element (FE) model. The FE model corresponded to a previously developed animal model in sheep. A prismatic implant filled a standardized defect in the load-bearing area of the trabecular bone beneath the tibial plateau. The interface was described by face-to-face contact elements, which allow press fits, friction, sliding, and gapping. We assumed a physiological load condition and calculated contact pressures, shear stresses, and shear movements at the interface for two implants of different stiffness (titanium: E = 110 GPa; composite: E = 2.2 GPa). The FE model showed that the stress distribution was more homogeneous for the low-stiffness implant. The maximum pressure for the composite implant (2.1 MPa) was lower than for the titanium implant (5.6 MPa). Contrary to our hypothesis, we found more micromotion for the composite (up to 6 mum) than for the titanium implant (up to 4.5 mum). However, for both implants peak stresses and micromotion were in a range that predicts adequate conditions for the osseointegration. This was confirmed by the histological results from the animal studies. (C) 2003 Elsevier Science Ltd. All rights reserved.

Useful keywords (using NLM MeSH Indexing)

Animals

Bone Substitutes*

Composite Resins

Computer Simulation

Elasticity

Equipment Failure Analysis/methods*

Finite Element Analysis

Models, Biological*

Motion*

Prosthesis Failure

Shear Strength

Sheep

Stress, Mechanical

Surface Properties

Tibia/abnormalities*

Tibia/physiopathology*

Tibia/surgery

Titanium

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