Implications of humeral short-stem diametral sizing on implant stability

Background: Shoulder arthroplasty humeral stem design has evolved to include various shapes, coatings, lengths, sizes, and fixation methods. While necessary to accommodate patient anatomy characteristics, this creates a surgical paradox of choice. The relationship between the surgeon’s selection of...

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Main Authors: Jacob M. Reeves, PhD, Gregory W. Spangenberg, BESc, Josie A. Elwell, PhD, Ben Stewart, BSID, Tom Vanasse, MSE, Chris Roche, MSE, MBA, Kenneth J. Faber, MD, FRCSC, G. Daniel G. Langohr, PhD
Format: Article
Language:English
Published: Elsevier 2023-11-01
Series:JSES International
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2666638323001718
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author Jacob M. Reeves, PhD
Gregory W. Spangenberg, BESc
Josie A. Elwell, PhD
Ben Stewart, BSID
Tom Vanasse, MSE
Chris Roche, MSE, MBA
Kenneth J. Faber, MD, FRCSC
G. Daniel G. Langohr, PhD
author_facet Jacob M. Reeves, PhD
Gregory W. Spangenberg, BESc
Josie A. Elwell, PhD
Ben Stewart, BSID
Tom Vanasse, MSE
Chris Roche, MSE, MBA
Kenneth J. Faber, MD, FRCSC
G. Daniel G. Langohr, PhD
author_sort Jacob M. Reeves, PhD
collection DOAJ
description Background: Shoulder arthroplasty humeral stem design has evolved to include various shapes, coatings, lengths, sizes, and fixation methods. While necessary to accommodate patient anatomy characteristics, this creates a surgical paradox of choice. The relationship between the surgeon’s selection of short-stem implant size and construct stiffness, resistance to subsidence and micromotion has not been assessed. Methods: Eight paired cadaveric humeri were reconstructed with surgeon-selected (SS) and 2-mm diametrically larger (SS+2) short-stemmed press-fit implants. Each reconstruction was subjected to 2000 cycles of 90° forward flexion loading, and stem subsidence and micromotion were measured using optical tracking. Compressive stiffness of the stem-bone reconstruction was then assessed by applying a load in-line with the stem axis that resulted in 5 mm of stem subsidence. Results: Increasing stem size by 2 mm resulted in the construct stiffness more than doubling compared to SS stems (−741 ± 243 N/mm vs. −334 ± 120 N/mm; P = .003; power = 0.971). These larger stems also subsided significantly less than their SS counterparts (SS: 1.2 ± 0.6 mm; SS+2: 0.5 ± 0.5 mm; P = .029; power = 0.66), though there were no significant changes in micromotion (SS: 169 ± 59 μm; SS+2: 187 ± 52 μm; P = .506; power = 0.094). Conclusions: The results of this study highlight the importance of proper short-stem sizing, as a relatively small 2 mm increase in diametral size was observed to significantly impact construct stiffness, which could increase the risk of stress shielding and implant loosening. Future work should focus on developing tools that objectively quantify bone quality and aid surgeons in selecting the appropriate size short-stem humeral implants for a particular patient.
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spelling doaj.art-e950dc5aa9834f80addab697291d54242023-10-28T05:09:49ZengElsevierJSES International2666-63832023-11-017624452453Implications of humeral short-stem diametral sizing on implant stabilityJacob M. Reeves, PhD0Gregory W. Spangenberg, BESc1Josie A. Elwell, PhD2Ben Stewart, BSID3Tom Vanasse, MSE4Chris Roche, MSE, MBA5Kenneth J. Faber, MD, FRCSC6G. Daniel G. Langohr, PhD7Department of Mechanical and Materials Engineering, The University of Western Ontario, London, ON, Canada; The Roth | McFarlane Hand and Upper Limb Centre, London, ON, CanadaDepartment of Mechanical and Materials Engineering, The University of Western Ontario, London, ON, Canada; The Roth | McFarlane Hand and Upper Limb Centre, London, ON, CanadaExactech, Inc., Gainesville, FL, USAExactech, Inc., Gainesville, FL, USAExactech, Inc., Gainesville, FL, USAExactech, Inc., Gainesville, FL, USADepartment of Mechanical and Materials Engineering, The University of Western Ontario, London, ON, Canada; The Roth | McFarlane Hand and Upper Limb Centre, London, ON, CanadaDepartment of Mechanical and Materials Engineering, The University of Western Ontario, London, ON, Canada; The Roth | McFarlane Hand and Upper Limb Centre, London, ON, Canada; Corresponding author: G. Daniel G. Langohr, PhD, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4L6, Canada.Background: Shoulder arthroplasty humeral stem design has evolved to include various shapes, coatings, lengths, sizes, and fixation methods. While necessary to accommodate patient anatomy characteristics, this creates a surgical paradox of choice. The relationship between the surgeon’s selection of short-stem implant size and construct stiffness, resistance to subsidence and micromotion has not been assessed. Methods: Eight paired cadaveric humeri were reconstructed with surgeon-selected (SS) and 2-mm diametrically larger (SS+2) short-stemmed press-fit implants. Each reconstruction was subjected to 2000 cycles of 90° forward flexion loading, and stem subsidence and micromotion were measured using optical tracking. Compressive stiffness of the stem-bone reconstruction was then assessed by applying a load in-line with the stem axis that resulted in 5 mm of stem subsidence. Results: Increasing stem size by 2 mm resulted in the construct stiffness more than doubling compared to SS stems (−741 ± 243 N/mm vs. −334 ± 120 N/mm; P = .003; power = 0.971). These larger stems also subsided significantly less than their SS counterparts (SS: 1.2 ± 0.6 mm; SS+2: 0.5 ± 0.5 mm; P = .029; power = 0.66), though there were no significant changes in micromotion (SS: 169 ± 59 μm; SS+2: 187 ± 52 μm; P = .506; power = 0.094). Conclusions: The results of this study highlight the importance of proper short-stem sizing, as a relatively small 2 mm increase in diametral size was observed to significantly impact construct stiffness, which could increase the risk of stress shielding and implant loosening. Future work should focus on developing tools that objectively quantify bone quality and aid surgeons in selecting the appropriate size short-stem humeral implants for a particular patient.http://www.sciencedirect.com/science/article/pii/S2666638323001718Shoulder arthroplastyStem stabilityMicromotionSubsidenceConstruct stiffnessShort stem
spellingShingle Jacob M. Reeves, PhD
Gregory W. Spangenberg, BESc
Josie A. Elwell, PhD
Ben Stewart, BSID
Tom Vanasse, MSE
Chris Roche, MSE, MBA
Kenneth J. Faber, MD, FRCSC
G. Daniel G. Langohr, PhD
Implications of humeral short-stem diametral sizing on implant stability
JSES International
Shoulder arthroplasty
Stem stability
Micromotion
Subsidence
Construct stiffness
Short stem
title Implications of humeral short-stem diametral sizing on implant stability
title_full Implications of humeral short-stem diametral sizing on implant stability
title_fullStr Implications of humeral short-stem diametral sizing on implant stability
title_full_unstemmed Implications of humeral short-stem diametral sizing on implant stability
title_short Implications of humeral short-stem diametral sizing on implant stability
title_sort implications of humeral short stem diametral sizing on implant stability
topic Shoulder arthroplasty
Stem stability
Micromotion
Subsidence
Construct stiffness
Short stem
url http://www.sciencedirect.com/science/article/pii/S2666638323001718
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