Original articlesStructural and mechanical properties of the glenohumeral joint posterior capsule
Section snippets
Specimen preparation
In this study 7 healthy, fresh-frozen human cadaveric shoulders (3 left and 4 right) from 7 persons were used. To determine the appropriate sample size, we conducted a statistical power analysis after testing the first 3 specimens. The analysis indicated that a sample size of 7 was necessary to achieve a power of 80% at a significance level of P < .05 (β = .2, α = .05). Specimens with severe glenohumeral joint arthritis or visible rotator cuff pathology (ie, degeneration or fraying) were
Geometry
Significant differences in tissue thickness were found among the 3 regions of the posterior capsule and the AB-IGHL (Figure 2). Specifically, the AB-IGHL was thicker than the INF-PC (P = .01) and MID-PC (P = .03), whereas the SUP-PC was thicker than the INF-PC (P = .02). Somewhat surprisingly, there was no statistically significant difference in thickness between the AB-IGHL and the SUP-PC (P = .53).
Material properties
There were relatively few differences in the material properties between the 3 regions of the
Discussion
The purpose of this study was to quantify regional variations in the material properties of the glenohumeral joint’s posterior capsule. Although we originally hypothesized that the material properties of the posterior capsule would be significantly inferior to those of the AB-IGHL, we found relatively few differences between the posterior capsule and the AB-IGHL.
Contrary to our expectations, the only differences that were detected between the 4 tissue bands were in failure strain and thickness.
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