In vitro testing of the primary stability of the VerSys enhanced taper stem

A comparative study in intact and intraoperatively cracked femora

L. Monti, L. Cristofolini, A. Toni, R. G. Ceroni

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The Zimmer VerSys enhanced taper uncemented stem was tested in vitro for primary stability. Six stems were implanted in six composite femora. Three femora were unintentionally damaged by cracking of the bone during stem insertion and press-fit. A previously validated protocol was used to load the specimens cyclically and to record locally the rotational and axial bone/implant relative motions in terms of elastic motion and permanent migration.For the undamaged femora, the VerSys stem showed excellent primary stability, in terms of both elastic motions (less than 9 ?m) and permanent migrations (less than 6 ?m), and in both axial and rotational directions, comparing favorably with the literature. Intraoperatively-induced proximal cracks did influence the primary stability of the stem in terms of permanent migration. As cracks may easily be produced in the diaphyseal canal during insertion of cementless stems, which rely for primary stability on conical fitting into the canal, great care must be taken in preparation of the canal and insertion of the stem.

Original languageEnglish
Pages (from-to)75-83
Number of pages9
JournalProceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
Volume215
Issue number1
DOIs
Publication statusPublished - 2015

Fingerprint

Femur
Canals
Testing
Bone and Bones
Bone
Cracks
In Vitro Techniques
Composite materials
Direction compound

Keywords

  • bone cracks
  • cementless prosthesis
  • mechanical test
  • micromotion
  • primary stability

ASJC Scopus subject areas

  • Mechanical Engineering
  • Medicine(all)

Cite this

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abstract = "The Zimmer VerSys enhanced taper uncemented stem was tested in vitro for primary stability. Six stems were implanted in six composite femora. Three femora were unintentionally damaged by cracking of the bone during stem insertion and press-fit. A previously validated protocol was used to load the specimens cyclically and to record locally the rotational and axial bone/implant relative motions in terms of elastic motion and permanent migration.For the undamaged femora, the VerSys stem showed excellent primary stability, in terms of both elastic motions (less than 9 ?m) and permanent migrations (less than 6 ?m), and in both axial and rotational directions, comparing favorably with the literature. Intraoperatively-induced proximal cracks did influence the primary stability of the stem in terms of permanent migration. As cracks may easily be produced in the diaphyseal canal during insertion of cementless stems, which rely for primary stability on conical fitting into the canal, great care must be taken in preparation of the canal and insertion of the stem.",
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AU - Cristofolini, L.

AU - Toni, A.

AU - Ceroni, R. G.

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N2 - The Zimmer VerSys enhanced taper uncemented stem was tested in vitro for primary stability. Six stems were implanted in six composite femora. Three femora were unintentionally damaged by cracking of the bone during stem insertion and press-fit. A previously validated protocol was used to load the specimens cyclically and to record locally the rotational and axial bone/implant relative motions in terms of elastic motion and permanent migration.For the undamaged femora, the VerSys stem showed excellent primary stability, in terms of both elastic motions (less than 9 ?m) and permanent migrations (less than 6 ?m), and in both axial and rotational directions, comparing favorably with the literature. Intraoperatively-induced proximal cracks did influence the primary stability of the stem in terms of permanent migration. As cracks may easily be produced in the diaphyseal canal during insertion of cementless stems, which rely for primary stability on conical fitting into the canal, great care must be taken in preparation of the canal and insertion of the stem.

AB - The Zimmer VerSys enhanced taper uncemented stem was tested in vitro for primary stability. Six stems were implanted in six composite femora. Three femora were unintentionally damaged by cracking of the bone during stem insertion and press-fit. A previously validated protocol was used to load the specimens cyclically and to record locally the rotational and axial bone/implant relative motions in terms of elastic motion and permanent migration.For the undamaged femora, the VerSys stem showed excellent primary stability, in terms of both elastic motions (less than 9 ?m) and permanent migrations (less than 6 ?m), and in both axial and rotational directions, comparing favorably with the literature. Intraoperatively-induced proximal cracks did influence the primary stability of the stem in terms of permanent migration. As cracks may easily be produced in the diaphyseal canal during insertion of cementless stems, which rely for primary stability on conical fitting into the canal, great care must be taken in preparation of the canal and insertion of the stem.

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