Mechanics of the canine femur with two types of hip replacement stems

R. Shahar; L. Banks-Sills; R. Eliasy

doi:10.1055/s-0038-1632770

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2003; 16(03): 145-52
DOI: 10.1055/s-0038-1632770

Original Research

Schattauer GmbH

Mechanics of the canine femur with two types of hip replacement stems

Finite element analysis

R. Shahar

¹Section of Surgery, Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Israel

,

L. Banks-Sills

²The Dreszer Fracture Mechanics Laboratory, Department of Solid Mechanics, Materials and Systems, The Fleischman Faculty of Engineering, Tel Aviv University, Israel

,

R. Eliasy

²The Dreszer Fracture Mechanics Laboratory, Department of Solid Mechanics, Materials and Systems, The Fleischman Faculty of Engineering, Tel Aviv University, Israel

› Author Affiliations

Abstract

Summary

The long-term performance of total hip replacement is of concern to veterinary surgeons. Two of the main complications associated with this procedure are implant loosening and stress shielding. Designs of the femoral stem which will avoid loosening and achieve maximum endurance while reducing stress shielding and periprosthetic bone loss are sought.

In the intact femur the stress is distributed over the entire cross section of the bone. After hip replacement this pattern of stress distribution is altered because of the manner in which the load is transferred from the prosthesis to the bone.

The objective of this study was to examine the stresses that develop in the femur and implant components of two different methods of hip replacement used clinically in dogs. Anatomic, three-dimensional finite element models of the canine femur with a cemented femoral stem and a Zurich cementless stem were constructed. The stresses and displacements were calculated by the finite element analysis method, under physiologic loads that included muscle forces and joint reaction forces. The results were compared to results obtained by a similar analysis of an intact femur.

This study demonstrates that the Zurich cementless method causes less stress shielding in the proximal femoral cortex than does the cemented method. Implant stresses are higher in the Zurich cementless stem, but still within an acceptable range.

Keywords

Finite element - femur - hip replacement

Full Text

References

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