Campi, S, Mellon, SJ, Ridley, D et al. (4 more authors) (2018) Optimal interference of the tibial component of the cementless Oxford Unicompartmental Knee Replacement. Bone & Joint Research, 7 (3). pp. 226-231. ISSN 2046-3758
Abstract
Objectives
The primary stability of the cementless Oxford Unicompartmental Knee Replacement (OUKR) relies on interference fit (or press fit). Insufficient interference may cause implant loosening, whilst excessive interference could cause bone damage and fracture. The aim of this study was to identify the optimal interference fit by measuring the force required to seat the tibial component of the cementless OUKR (push-in force) and the force required to remove the component (pull-out force).
Materials and Methods
Six cementless OUKR tibial components were implanted in 12 new slots prepared on blocks of solid polyurethane foam (20 pounds per cubic foot (PCF), Sawbones, Malmo, Sweden) with a range of interference of 0.1 mm to 1.9 mm using a Dartec materials testing machine HC10 (Zwick Ltd, Herefordshire, United Kingdom). The experiment was repeated with cellular polyurethane foam (15 PCF), which is a more porous analogue for trabecular bone.
Results
The push-in force progressively increased with increasing interference. The pull-out force was related in a non-linear fashion to interference, decreasing with higher interference. Compared with the current nominal interference, a lower interference would reduce the push-in forces by up to 45% (p < 0.001 One way ANOVA) ensuring comparable (or improved) pull-out forces (p > 0.05 Bonferroni post hoc test). With the more porous bone analogue, although the forces were lower, the relationship between interference and push-in and pull-out force were similar.
Conclusions
This study suggests that decreasing the interference fit of the tibial component of the cementless OUKR reduces the push-in force and can increase the pull-out force. An optimal interference fit may both improve primary fixation and decrease the risk of fracture.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 Author(s) et al. This is an open-access article distributed under the terms of the Creative Commons Attributions licence (CC-BY-NC), which permits unrestricted use, distribution, and reproduction in any medium, but not for commercial gain, provided the original author and source are credited. |
Keywords: | Interference fit; Cementless implants; Push-in force; Pull-out force |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Medicine (Leeds) > Institute of Rheumatology & Musculoskeletal Medicine (LIRMM) (Leeds) > Orthopaedics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 25 Sep 2018 10:41 |
Last Modified: | 09 Jan 2020 16:54 |
Status: | Published |
Publisher: | British Editorial Society of Bone and Joint Surgery |
Identification Number: | 10.1302/2046-3758.73.BJR-2017-0193.R1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:136179 |