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TECHNICAL PAPERS: Joint/Whole Body

# The Effect of the Loading Condition Corresponding to Functional Shoulder Activities on Trabecular Architecture of Glenoid

[+] Author and Article Information
Dohyung Lim, Rami Seliktar, Jin-Yong Wee

School of Biomedical Engineering, Drexel University, Philadelphia, PA 19104

James Tom

Orthopaedic Surgery Control, Health Science, Drexel University, Philadelphia, PA 19104

Linda Nunes

J Biomech Eng 128(2), 250-258 (Oct 18, 2005) (9 pages) doi:10.1115/1.2165698 History: Received November 11, 2004; Revised October 18, 2005

## Abstract

There is little information on bone morphology as it relates to shoulder activities. This study investigated how loads corresponding to functional shoulder activities affect the trabecular architecture of the glenoid. Two different protocols were used. Protocol 1 investigated the material and morphological characteristics of the glenoid by analyzing digitized trabecular bone images obtained from 12 cadaver scapula specimens. Protocol 2 used a finite element analysis (FEA) to compute the principal stress trajectories acting within the glenoid. The principal stresses were derived for five loading conditions, which represent typical functional shoulder activities. The study showed that shoulder activity involved in carrying a light load makes the greatest contribution to the trabecular architecture compared with other shoulder activities considered in this study $(p<0.05)$. With all of the activities considered in this study, the lateral region, particularly in the anterior and posterior portions, showed greater deviation and greater sensitivity to variation under loading conditions than did the other regions $(p<0.05)$. These results suggest that owing to the extra sensitivity of the anterior and posterior parts of the lateral region, these regions may be more informative in the analysis of the trabecular architecture following shoulder musculoskeletal injuries. These results may provide essential design information for shoulder prostheses and contribute to an understanding of morphological changes resulting from injury.

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## Figures

Figure 1

Schematic of the location of the regions of interest (ROIs) in the mediolateral (above), supero-inferior (center), and anteroposterior (bottom) views

Figure 2

Predominant trabecular directions (average angle) and their distributions (standard deviation) in the ROIs. The values are obtained from 12 cadaveric specimens. Straight, dashed, and dotted arrows represent the predominant directions in the upper, bare, and lower regions, respectively. The values in the first, second, and third rows in the ROIs are the predominant numerical angles in the upper, bare, and lower regions, respectively.

Figure 3

The trajectories (direction) and magnitudes of the primary principal stresses computed from the FE model under the validation procedure. The straight, dashed, and dotted arrows on each ROI represent the direction of the primary principal stress in the upper, bare, and lower regions, respectively. The values in the first, second, and third rows, to the right of each ROI, are the numerical values of the primary principal stress directions in the upper, bare, and lower regions, respectively. The values in the first, second, and third rows below each ROI indicate the principal stress magnitudes (MPa) in the upper, bare, and lower regions, respectively.

Figure 4

The trajectories of the primary principal stresses computed from loading case 1

Figure 5

The trajectories of the primary principal stresses computed from loading case 2

Figure 6

The trajectories of the primary principal stresses computed from loading case 3

Figure 7

The trajectories of the primary principal stresses computed from loading case 4

Figure 8

The trajectories of the primary principal stresses computed from loading case 5

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