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Computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation

PURPOSE: Functional internal rotation (IR) is a combination of extension and IR. It is clinically often limited after reverse total shoulder arthroplasty (RTSA) either due to loss of extension or IR in extension. It was the purpose of this study to determine the ideal in-vitro combination of glenoid...

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Autores principales: Hochreiter, Bettina, Meisterhans, Michel, Zindel, Christoph, Calek, Anna-Katharina, Gerber, Christian
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Berlin Heidelberg 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10014642/
https://www.ncbi.nlm.nih.gov/pubmed/36917396
http://dx.doi.org/10.1186/s40634-023-00580-5
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author Hochreiter, Bettina
Meisterhans, Michel
Zindel, Christoph
Calek, Anna-Katharina
Gerber, Christian
author_facet Hochreiter, Bettina
Meisterhans, Michel
Zindel, Christoph
Calek, Anna-Katharina
Gerber, Christian
author_sort Hochreiter, Bettina
collection PubMed
description PURPOSE: Functional internal rotation (IR) is a combination of extension and IR. It is clinically often limited after reverse total shoulder arthroplasty (RTSA) either due to loss of extension or IR in extension. It was the purpose of this study to determine the ideal in-vitro combination of glenoid and humeral components to achieve impingement-free functional IR. METHODS: RTSA components were virtually implanted into a normal scapula (previously established with a statistical shape model) and into a corresponding humerus using a computer planning program (CASPA). Baseline glenoid configuration consisted of a 28 mm baseplate placed flush with the posteroinferior glenoid rim, a baseplate inclination angle of 96° (relative to the supraspinatus fossa) and a 36 mm standard glenosphere. Baseline humeral configuration consisted of a 12 mm humeral stem, a metaphysis with a neck shaft angle (NSA) of 155° (+ 6 mm medial offset), anatomic torsion of -20° and a symmetric PE inlay (36mmx0mm). Additional configurations with different humeral torsion (-20°, + 10°), NSA (135°, 145°, 155°), baseplate position, diameter, lateralization and inclination were tested. Glenohumeral extension of 5, 10, 20, and 40° was performed first, followed by IR of 20, 40, and 60° with the arm in extension of 40°—the value previously identified as necessary for satisfactory clinical functional IR. The different component combinations were taken through simulated ROM and the impingement volume (mm(3)) was recorded. Furthermore, the occurrence of impingement was read out in 5° motion increments. RESULTS: In all cases where impingement occurred, it occurred between the PE inlay and the posterior glenoid rim. Only in 11 of 36 combinations full functional IR was possible without impingement. Anterosuperior baseplate positioning showed the highest impingement volume with every combination of NSA and torsion. A posteroinferiorly positioned 26 mm baseplate resulting in an additional 2 mm of inferior overhang as well as 6 mm baseplate lateralization offered the best impingement-free functional IR (5/6 combinations without impingement). Low impingement potential resulted from a combination of NSA 135° and + 10° torsion (4/6 combinations without impingement), followed by NSA 135° and -20° torsion (3/6 combinations without impingement) regardless of glenoid setup. CONCLUSION: The largest impingement-free functional IRs resulted from combining a posteroinferior baseplate position, a greater inferior glenosphere overhang, 90° of baseplate inclination angle, 6 mm glenosphere lateralization with respect to baseline setup, a lower NSA and antetorsion of the humeral component. Surgeons can employ and combine these implant configurations to achieve and improve functional IR when planning and performing RTSA. LEVEL OF EVIDENCE: Basic Science Study, Biomechanics.
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spelling pubmed-100146422023-03-16 Computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation Hochreiter, Bettina Meisterhans, Michel Zindel, Christoph Calek, Anna-Katharina Gerber, Christian J Exp Orthop Original Paper PURPOSE: Functional internal rotation (IR) is a combination of extension and IR. It is clinically often limited after reverse total shoulder arthroplasty (RTSA) either due to loss of extension or IR in extension. It was the purpose of this study to determine the ideal in-vitro combination of glenoid and humeral components to achieve impingement-free functional IR. METHODS: RTSA components were virtually implanted into a normal scapula (previously established with a statistical shape model) and into a corresponding humerus using a computer planning program (CASPA). Baseline glenoid configuration consisted of a 28 mm baseplate placed flush with the posteroinferior glenoid rim, a baseplate inclination angle of 96° (relative to the supraspinatus fossa) and a 36 mm standard glenosphere. Baseline humeral configuration consisted of a 12 mm humeral stem, a metaphysis with a neck shaft angle (NSA) of 155° (+ 6 mm medial offset), anatomic torsion of -20° and a symmetric PE inlay (36mmx0mm). Additional configurations with different humeral torsion (-20°, + 10°), NSA (135°, 145°, 155°), baseplate position, diameter, lateralization and inclination were tested. Glenohumeral extension of 5, 10, 20, and 40° was performed first, followed by IR of 20, 40, and 60° with the arm in extension of 40°—the value previously identified as necessary for satisfactory clinical functional IR. The different component combinations were taken through simulated ROM and the impingement volume (mm(3)) was recorded. Furthermore, the occurrence of impingement was read out in 5° motion increments. RESULTS: In all cases where impingement occurred, it occurred between the PE inlay and the posterior glenoid rim. Only in 11 of 36 combinations full functional IR was possible without impingement. Anterosuperior baseplate positioning showed the highest impingement volume with every combination of NSA and torsion. A posteroinferiorly positioned 26 mm baseplate resulting in an additional 2 mm of inferior overhang as well as 6 mm baseplate lateralization offered the best impingement-free functional IR (5/6 combinations without impingement). Low impingement potential resulted from a combination of NSA 135° and + 10° torsion (4/6 combinations without impingement), followed by NSA 135° and -20° torsion (3/6 combinations without impingement) regardless of glenoid setup. CONCLUSION: The largest impingement-free functional IRs resulted from combining a posteroinferior baseplate position, a greater inferior glenosphere overhang, 90° of baseplate inclination angle, 6 mm glenosphere lateralization with respect to baseline setup, a lower NSA and antetorsion of the humeral component. Surgeons can employ and combine these implant configurations to achieve and improve functional IR when planning and performing RTSA. LEVEL OF EVIDENCE: Basic Science Study, Biomechanics. Springer Berlin Heidelberg 2023-03-14 /pmc/articles/PMC10014642/ /pubmed/36917396 http://dx.doi.org/10.1186/s40634-023-00580-5 Text en © The Author(s) 2023 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Original Paper
Hochreiter, Bettina
Meisterhans, Michel
Zindel, Christoph
Calek, Anna-Katharina
Gerber, Christian
Computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation
title Computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation
title_full Computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation
title_fullStr Computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation
title_full_unstemmed Computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation
title_short Computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation
title_sort computer-assisted analysis of functional internal rotation after reverse total shoulder arthroplasty: implications for component choice and orientation
topic Original Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10014642/
https://www.ncbi.nlm.nih.gov/pubmed/36917396
http://dx.doi.org/10.1186/s40634-023-00580-5
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