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Influence of prosthesis design and implantation technique on implant stresses after cementless revision THR

Influence of prosthesis design and implantation technique on implant stresses after cementless revision THR
Influence of prosthesis design and implantation technique on implant stresses after cementless revision THR
BACKGROUND: Femoral offset influences the forces at the hip and the implant stresses after revision THR. For extended bone defects, these forces may cause considerable bending moments within the implant, possibly leading to implant failure. This study investigates the influences of femoral anteversion and offset on stresses in the Wagner SL revision stem implant under varying extents of bone defect conditions. METHODS: Wagner SL revision stems with standard (34 mm) and increased offset (44 mm) were virtually implanted in a model femur with bone defects of variable extent (Paprosky I to IIIb). Variations in surgical technique were simulated by implanting the stems each at 4 degrees or 14 degrees of anteversion. Muscle and joint contact forces were applied to the reconstruction and implant stresses were determined using finite element analyses. RESULTS: Whilst increasing the implant's offset by 10 mm led to increased implant stresses (16.7% in peak tensile stresses), altering anteversion played a lesser role (5%). Generally, larger stresses were observed with reduced bone support: implant stresses increased by as much as 59% for a type IIIb defect. With increased offset, the maximum tensile stress was 225 MPa. CONCLUSION: Although increased stresses were observed within the stem with larger offset and increased anteversion, these findings indicate that restoration of offset, key to restoring joint function, is unlikely to result in excessive implant stresses under routine activities if appropriate fixation can be achieved.
1749-799X
20-[9pp]
Heller, Markus O.
3da19d2a-f34d-4ff1-8a34-9b5a7e695829
Mehta, Manav
0e14de1e-7040-4eda-83cb-d5d6151a12df
Taylor, William R.
1ed48ef6-e396-40f5-8434-6c0628c9d3ca
Kim, Dong-Yeong
6eb18979-a712-4255-868a-204714dcb6e8
Speirs, Speirs
4f4385f1-09ea-4fd6-a2d6-45418cb1a8de
Duda, Georg N.
ac4e207b-3e2e-4c84-a6c4-cb67531f890b
Perka, Carsten
50eac0cf-e710-45df-a04b-b8af775eace1
Heller, Markus O.
3da19d2a-f34d-4ff1-8a34-9b5a7e695829
Mehta, Manav
0e14de1e-7040-4eda-83cb-d5d6151a12df
Taylor, William R.
1ed48ef6-e396-40f5-8434-6c0628c9d3ca
Kim, Dong-Yeong
6eb18979-a712-4255-868a-204714dcb6e8
Speirs, Speirs
4f4385f1-09ea-4fd6-a2d6-45418cb1a8de
Duda, Georg N.
ac4e207b-3e2e-4c84-a6c4-cb67531f890b
Perka, Carsten
50eac0cf-e710-45df-a04b-b8af775eace1

Heller, Markus O., Mehta, Manav, Taylor, William R., Kim, Dong-Yeong, Speirs, Speirs, Duda, Georg N. and Perka, Carsten (2011) Influence of prosthesis design and implantation technique on implant stresses after cementless revision THR. Journal of Orthopaedic Surgery and Research, 6 (1), 20-[9pp]. (doi:10.1186/1749-799X-6-20). (PMID:21569522)

Record type: Article

Abstract

BACKGROUND: Femoral offset influences the forces at the hip and the implant stresses after revision THR. For extended bone defects, these forces may cause considerable bending moments within the implant, possibly leading to implant failure. This study investigates the influences of femoral anteversion and offset on stresses in the Wagner SL revision stem implant under varying extents of bone defect conditions. METHODS: Wagner SL revision stems with standard (34 mm) and increased offset (44 mm) were virtually implanted in a model femur with bone defects of variable extent (Paprosky I to IIIb). Variations in surgical technique were simulated by implanting the stems each at 4 degrees or 14 degrees of anteversion. Muscle and joint contact forces were applied to the reconstruction and implant stresses were determined using finite element analyses. RESULTS: Whilst increasing the implant's offset by 10 mm led to increased implant stresses (16.7% in peak tensile stresses), altering anteversion played a lesser role (5%). Generally, larger stresses were observed with reduced bone support: implant stresses increased by as much as 59% for a type IIIb defect. With increased offset, the maximum tensile stress was 225 MPa. CONCLUSION: Although increased stresses were observed within the stem with larger offset and increased anteversion, these findings indicate that restoration of offset, key to restoring joint function, is unlikely to result in excessive implant stresses under routine activities if appropriate fixation can be achieved.

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More information

Published date: May 2011
Organisations: Bioengineering Group

Identifiers

Local EPrints ID: 348530
URI: http://eprints.soton.ac.uk/id/eprint/348530
ISSN: 1749-799X
PURE UUID: 43b36731-efd7-45b2-be7d-ed476536cbf3
ORCID for Markus O. Heller: ORCID iD orcid.org/0000-0002-7879-1135

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Date deposited: 15 Feb 2013 08:30
Last modified: 20 Jul 2019 00:41

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