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J Orthop Sports Phys Ther. 2012 Feb;42(2):96-104. doi: 10.2519/jospt.2012.3584. Epub 2011 Oct 25.

Dynamic in vivo glenohumeral kinematics during scapular plane abduction in healthy shoulders.

Author information

1
Teikyo University Chiba Medical Center, Department of Orthopaedic Surgery, Ichihara, Chiba, Japan. kmatsuki@med.teikyo-u.ac.jp

Abstract

STUDY DESIGN:

Controlled laboratory study.

OBJECTIVES:

To measure superior/inferior translation and external rotation of the humerus relative to the scapula during scapular plane abduction using 3-D/2-D model image registration techniques.

BACKGROUND:

Kinematic changes in the glenohumeral joint, including excessive superior translation of the humeral head and inadequate external rotation of the humerus, are believed to be a possible cause of shoulder impingement. Although many researchers have analyzed glenohumeral kinematics with various methods, few articles have assessed dynamic in vivo glenohumeral motion.

METHODS:

Twelve healthy males with a mean age of 32 years (range, 27-36 years) were enrolled in this study. Fluoroscopic images of the dominant shoulder during scapular plane elevation were taken, and computed tomography-derived 3-D bone models were matched with the silhouette of the bones in the fluoroscopic images using 3-D/2-D model image registration techniques. The kinematics of the humerus relative to the scapula were determined using Euler angles.

RESULTS:

On average, there was 2.1 mm of initial humeral translation in the superior direction from the starting position to 105° of humeral elevation. Subsequently, an average of 0.9 mm of translation in the inferior direction occurred between 105° and maximum arm elevation. The average amount of external rotation of the humerus was 14° from the starting position to 60° of humeral elevation. The humerus then rotated internally an average 9° by the time the shoulder reached maximum elevation. These changes in superior/inferior translation and external/internal rotation were statistically significant (P<.001 and P = .001, respectively), based on 1-way repeated-measures analysis of variance.

CONCLUSION:

The observed glenohumeral translations and rotations characterize healthy shoulder function and serve as a preliminary foundation for quantifying pathomechanics in the presence of glenohumeral joint disorders.

PMID:
22030448
DOI:
10.2519/jospt.2012.3584
[Indexed for MEDLINE]

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