Dynamic glenohumeral stability provided by the rotator cuff muscles in the mid-range and end-range of motion: A study in cadavera

Seok Beom Lee, Kyu Jung Kim, Shawn W. O'Driscoll, Bernard F. Morrey, Kai Nan An

Research output: Contribution to journalArticle

176 Citations (Scopus)

Abstract

Background: Both static and dynamic factors are responsible for glenohumeral joint stability. We hypothesized that dynamic factors could potentially operate throughout the entire range of glenohumeral motion, although capsuloligamentous restraints (a static factor) have been thought to be primarily responsible for stability in the end-range of motion. The purpose of this study was to quantitatively compare the dynamic glenohumeral joint stability in the end-range of motion (the position of anterior instability) with that in the mid-range by investigating the force components generated by the rotator cuff muscles. Methods: Ten fresh-frozen shoulders from human cadavera were obtained, and all soft tissues except the rotator cuff were removed. The glenohumeral capsule was resected after the rotator cuff muscles had been released from the scapula. A specially designed frame positioned the humerus in 60 degrees of abduction and 45 degrees of extension with respect to the scapula. The compressive and shear components on the glenoid were measured before and after a constant force was applied individually to each muscle with the humerus in five different positions (from neutral to 90 degrees of external rotation). The dynamic stability index, a new biomechanical parameter reflecting these force components and the concavity-compression mechanism, was calculated. The higher the dynamic stability index, the greater the dynamic glenohumeral stability. Results: In the mid-range of motion, the supraspinatus and subscapularis provided higher dynamic stability indices than did the other muscles (p < 0.05). On the other hand, when the position of anterior instability was simulated in the end- range of motion, the subscapularis, infraspinatus, and teres minor provided significantly higher dynamic stability indices than did the supraspinatus (p < 0.005). Conclusions: The rotator cuff provided substantial anterior dynamic stability to the glenohumeral joint in the end-range of motion as well as in the mid-range. Clinical Relevance: A glenohumeral joint with a lax capsule and ligaments might be stabilized dynamically in the end-range of motion if the glenoid concavity is maintained and the function of the external and internal rotators, which are efficient stabilizers in this position, is enhanced.

Original languageEnglish (US)
Pages (from-to)849-857
Number of pages9
JournalJournal of Bone and Joint Surgery - Series A
Volume82
Issue number6
StatePublished - Jun 2000

Fingerprint

Rotator Cuff
Articular Range of Motion
Cadaver
Muscles
Shoulder Joint
Scapula
Humerus
Capsules
Bursitis
Ligaments

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine

Cite this

Dynamic glenohumeral stability provided by the rotator cuff muscles in the mid-range and end-range of motion : A study in cadavera. / Lee, Seok Beom; Kim, Kyu Jung; O'Driscoll, Shawn W.; Morrey, Bernard F.; An, Kai Nan.

In: Journal of Bone and Joint Surgery - Series A, Vol. 82, No. 6, 06.2000, p. 849-857.

Research output: Contribution to journalArticle

Lee, Seok Beom ; Kim, Kyu Jung ; O'Driscoll, Shawn W. ; Morrey, Bernard F. ; An, Kai Nan. / Dynamic glenohumeral stability provided by the rotator cuff muscles in the mid-range and end-range of motion : A study in cadavera. In: Journal of Bone and Joint Surgery - Series A. 2000 ; Vol. 82, No. 6. pp. 849-857.
@article{4261f01b36f647578b2e087ce9c5d201,
title = "Dynamic glenohumeral stability provided by the rotator cuff muscles in the mid-range and end-range of motion: A study in cadavera",
abstract = "Background: Both static and dynamic factors are responsible for glenohumeral joint stability. We hypothesized that dynamic factors could potentially operate throughout the entire range of glenohumeral motion, although capsuloligamentous restraints (a static factor) have been thought to be primarily responsible for stability in the end-range of motion. The purpose of this study was to quantitatively compare the dynamic glenohumeral joint stability in the end-range of motion (the position of anterior instability) with that in the mid-range by investigating the force components generated by the rotator cuff muscles. Methods: Ten fresh-frozen shoulders from human cadavera were obtained, and all soft tissues except the rotator cuff were removed. The glenohumeral capsule was resected after the rotator cuff muscles had been released from the scapula. A specially designed frame positioned the humerus in 60 degrees of abduction and 45 degrees of extension with respect to the scapula. The compressive and shear components on the glenoid were measured before and after a constant force was applied individually to each muscle with the humerus in five different positions (from neutral to 90 degrees of external rotation). The dynamic stability index, a new biomechanical parameter reflecting these force components and the concavity-compression mechanism, was calculated. The higher the dynamic stability index, the greater the dynamic glenohumeral stability. Results: In the mid-range of motion, the supraspinatus and subscapularis provided higher dynamic stability indices than did the other muscles (p < 0.05). On the other hand, when the position of anterior instability was simulated in the end- range of motion, the subscapularis, infraspinatus, and teres minor provided significantly higher dynamic stability indices than did the supraspinatus (p < 0.005). Conclusions: The rotator cuff provided substantial anterior dynamic stability to the glenohumeral joint in the end-range of motion as well as in the mid-range. Clinical Relevance: A glenohumeral joint with a lax capsule and ligaments might be stabilized dynamically in the end-range of motion if the glenoid concavity is maintained and the function of the external and internal rotators, which are efficient stabilizers in this position, is enhanced.",
author = "Lee, {Seok Beom} and Kim, {Kyu Jung} and O'Driscoll, {Shawn W.} and Morrey, {Bernard F.} and An, {Kai Nan}",
year = "2000",
month = "6",
language = "English (US)",
volume = "82",
pages = "849--857",
journal = "Journal of Bone and Joint Surgery - American Volume",
issn = "0021-9355",
publisher = "Journal of Bone and Joint Surgery Inc.",
number = "6",

}

TY - JOUR

T1 - Dynamic glenohumeral stability provided by the rotator cuff muscles in the mid-range and end-range of motion

T2 - A study in cadavera

AU - Lee, Seok Beom

AU - Kim, Kyu Jung

AU - O'Driscoll, Shawn W.

AU - Morrey, Bernard F.

AU - An, Kai Nan

PY - 2000/6

Y1 - 2000/6

N2 - Background: Both static and dynamic factors are responsible for glenohumeral joint stability. We hypothesized that dynamic factors could potentially operate throughout the entire range of glenohumeral motion, although capsuloligamentous restraints (a static factor) have been thought to be primarily responsible for stability in the end-range of motion. The purpose of this study was to quantitatively compare the dynamic glenohumeral joint stability in the end-range of motion (the position of anterior instability) with that in the mid-range by investigating the force components generated by the rotator cuff muscles. Methods: Ten fresh-frozen shoulders from human cadavera were obtained, and all soft tissues except the rotator cuff were removed. The glenohumeral capsule was resected after the rotator cuff muscles had been released from the scapula. A specially designed frame positioned the humerus in 60 degrees of abduction and 45 degrees of extension with respect to the scapula. The compressive and shear components on the glenoid were measured before and after a constant force was applied individually to each muscle with the humerus in five different positions (from neutral to 90 degrees of external rotation). The dynamic stability index, a new biomechanical parameter reflecting these force components and the concavity-compression mechanism, was calculated. The higher the dynamic stability index, the greater the dynamic glenohumeral stability. Results: In the mid-range of motion, the supraspinatus and subscapularis provided higher dynamic stability indices than did the other muscles (p < 0.05). On the other hand, when the position of anterior instability was simulated in the end- range of motion, the subscapularis, infraspinatus, and teres minor provided significantly higher dynamic stability indices than did the supraspinatus (p < 0.005). Conclusions: The rotator cuff provided substantial anterior dynamic stability to the glenohumeral joint in the end-range of motion as well as in the mid-range. Clinical Relevance: A glenohumeral joint with a lax capsule and ligaments might be stabilized dynamically in the end-range of motion if the glenoid concavity is maintained and the function of the external and internal rotators, which are efficient stabilizers in this position, is enhanced.

AB - Background: Both static and dynamic factors are responsible for glenohumeral joint stability. We hypothesized that dynamic factors could potentially operate throughout the entire range of glenohumeral motion, although capsuloligamentous restraints (a static factor) have been thought to be primarily responsible for stability in the end-range of motion. The purpose of this study was to quantitatively compare the dynamic glenohumeral joint stability in the end-range of motion (the position of anterior instability) with that in the mid-range by investigating the force components generated by the rotator cuff muscles. Methods: Ten fresh-frozen shoulders from human cadavera were obtained, and all soft tissues except the rotator cuff were removed. The glenohumeral capsule was resected after the rotator cuff muscles had been released from the scapula. A specially designed frame positioned the humerus in 60 degrees of abduction and 45 degrees of extension with respect to the scapula. The compressive and shear components on the glenoid were measured before and after a constant force was applied individually to each muscle with the humerus in five different positions (from neutral to 90 degrees of external rotation). The dynamic stability index, a new biomechanical parameter reflecting these force components and the concavity-compression mechanism, was calculated. The higher the dynamic stability index, the greater the dynamic glenohumeral stability. Results: In the mid-range of motion, the supraspinatus and subscapularis provided higher dynamic stability indices than did the other muscles (p < 0.05). On the other hand, when the position of anterior instability was simulated in the end- range of motion, the subscapularis, infraspinatus, and teres minor provided significantly higher dynamic stability indices than did the supraspinatus (p < 0.005). Conclusions: The rotator cuff provided substantial anterior dynamic stability to the glenohumeral joint in the end-range of motion as well as in the mid-range. Clinical Relevance: A glenohumeral joint with a lax capsule and ligaments might be stabilized dynamically in the end-range of motion if the glenoid concavity is maintained and the function of the external and internal rotators, which are efficient stabilizers in this position, is enhanced.

UR - http://www.scopus.com/inward/record.url?scp=0034044608&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034044608&partnerID=8YFLogxK

M3 - Article

C2 - 10859105

AN - SCOPUS:0034044608

VL - 82

SP - 849

EP - 857

JO - Journal of Bone and Joint Surgery - American Volume

JF - Journal of Bone and Joint Surgery - American Volume

SN - 0021-9355

IS - 6

ER -