Document Detail

Nonconforming glenoid increases posterior glenohumeral translation after a total shoulder replacement.
MedLine Citation:
PMID:  24939381     Owner:  NLM     Status:  Publisher    
BACKGROUND: The major complication in nonconforming total shoulder replacement (TSR) is glenoid loosening and is attributed to posteriorly directed humeral head translations. Whether the posterior translations observed clinically are induced by radial mismatch is unclear. The objective of our study was to explain the posterior glenohumeral translations observed clinically after TSR by determining the glenohumeral translation and contact force as a function of radial mismatch. We hypothesized that the posterior direction of glenohumeral translation during scaption would be related to the radial mismatch and that the joint contact force would increase as the radial mismatch increased.
METHODS: A 6-degrees-of-freedom computational model of the glenohumeral joint was developed. We determined the muscle forces, joint contact force, and glenohumeral translation for radial mismatches from 1 mm to 20 mm with the shoulder positioned from 20° to 60° of scaption.
RESULTS: As the radial mismatch increased, the contact location of the humeral head moved posteriorly and inferiorly. The middle deltoid force decreased by 3%, while the supraspinatus and infraspinatus muscle forces increased by 9% and 11%, respectively. The joint contact force remained relatively constant.
CONCLUSIONS: Increased posterior glenohumeral translations were observed with increased radial mismatch. Clinical observations of posterior translation may be attributed to the balancing forces of the middle deltoid, infraspinatus, and supraspinatus muscles. High radial mismatches may lead to eccentric posterior loading on the glenoid component, which could lead to implant loosening and failure.
Radhika J Patel; Daniel Choi; Timothy Wright; Yingxin Gao
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-6-14
Journal Detail:
Title:  Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.]     Volume:  -     ISSN:  1532-6500     ISO Abbreviation:  J Shoulder Elbow Surg     Publication Date:  2014 Jun 
Date Detail:
Created Date:  2014-6-18     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9206499     Medline TA:  J Shoulder Elbow Surg     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.
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