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Effect of Plane of Arm Elevation on Glenohumeral KinematicsA Normative Biplane Fluoroscopy Study
J. Erik Giphart, PhD1; John P. Brunkhorst, BA1; Nils H. Horn, MD1; Kevin B. Shelburne, PhD2; Michael R. Torry, PhD3; Peter J. Millett, MD, MSc4
1 Department of BioMedical Engineering, Steadman Philippon Research Institute, 181 West Meadow Drive, Suite 1000, Vail, CO 81657.
2 Department of Mechanical and Materials Engineering, the University of Denver, 2390 South York Street, Denver, CO 80208
3 College of Applied Science and Technology, School of Kinesiology and Recreation, Campus Box 5120, Illinois State University, Normal, IL 61790
4 The Steadman Clinic, 181 West Meadow Drive, Suite 400, Vail, CO 81657 E-mail address: drmillett@thesteadmanclinic.com
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Investigation performed at the Department of BioMedical Engineering, Steadman Philippon Research Institute, Vail, Colorado

Disclosure: One or more of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of an aspect of this work. In addition, one or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, one or more of the authors has had another relationship, or has engaged in another activity, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.

Copyright © 2013 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2013 Feb 06;95(3):238-245. doi: 10.2106/JBJS.J.01875
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Understanding glenohumeral motion in normal and pathologic states requires the precise measurement of shoulder kinematics. The effect of the plane of arm elevation on glenohumeral translations and rotations remains largely unknown. The purpose of this study was to measure the three-dimensional glenohumeral translations and rotations during arm elevation in healthy subjects.


Eight male subjects performed scaption and forward flexion, and five subjects (three men and two women) performed abduction, inside a dynamic biplane fluoroscopy system. Bone geometries were extracted from computed tomography images and used to determine the three-dimensional position and orientation of the humerus and scapula in individual frames. Descriptive statistics were determined for glenohumeral joint rotations and translations, and linear regressions were performed to calculate the scapulohumeral rhythm ratio.


The scapulohumeral rhythm ratio was 2.0 ± 0.4:1 for abduction, 1.6 ± 0.5:1 for scaption, and 1.1 ± 0.3:1 for forward flexion, with the ratio for forward flexion being significantly lower than that for abduction (p = 0.002). Humeral head excursion was largest in abduction (5.1 ± 1.1 mm) and smallest in scaption (2.4 ± 0.6 mm) (p < 0.001). The direction of translation, as determined by the linear regression slope, was more inferior during abduction (−2.1 ± 1.8 mm/90°) compared with forward flexion (0.1 ± 10.9 mm/90°) (p = 0.024).


Scapulohumeral rhythm significantly decreased as the plane of arm elevation moved in an anterior arc from abduction to forward flexion. The amount of physiologic glenohumeral excursion varied significantly with the plane of elevation, was smallest for scaption, and showed inconsistent patterns across subjects with the exception of consistent inferior translation during abduction.

Clinical Relevance: 

When evaluating scapulohumeral kinematics during clinical assessment or for rehabilitation protocols, it is important to take into account and control the plane of arm elevation. Abnormalities in scapular motion may be better evaluated during forward flexion of the arm because greater scapular motion is required for this arm motion.

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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