The compressive behavior of the human glenoid labrum may explain the common patterns of SLAP lesions.
OBJECTIVE
The aim of the study was to define the normalized compressive stiffness (modulus) of the glenoid labrum around its circumference and to characterize the difference in modulus between different areas.


METHODS
Sixteen fresh-frozen cadaveric shoulders were harvested and dissected down to the glenoid labrum. Any specimens with significant degenerative changes were discarded, leaving 8 labra for testing. The labrum was divided into 8 segments, to allow comparison around its circumference. A uniform testing specimen was produced from each area by use of a microtome. Each specimen measured 3 x 1 mm in cross section and was 6 mm in length. Indentation testing was conducted in a controlled environment of 100% humidity at 37 degrees C +/- 1 degrees C.


RESULTS
We obtained 52 test samples from 8 labra. The mean modulus of the glenoid labrum was 69.7 megapascal (standard deviation, 36.2 megapascal). The anterosuperior portion of the labrum had a higher modulus than the posteroinferior portion (P = .0075).


CONCLUSIONS
This study has shown that the human glenoid labrum's compressive behavior varies around its circumference. The greater modulus of the anterosuperior portion of the labrum supports the theory that this area is anatomically different from the rest of the labrum and resists compressive loads.


CONCLUSIONS
These results may explain why the common type of SLAP lesions seen show failure at the interface between the labrum and the glenoid rather than within the substance of the labrum itself.
Smith
Chris D
CD
Department of Bioengineering, Imperial College London, London, England.
Masouros
Spyridon D
SD
Hill
Adam M
AM
Wallace
Andrew L
AL
Amis
Andrew A
AA
Bull
Anthony M J
AM
D000368:Aged; D001182:Arthroscopy; D004548:Elasticity; D005260:Female; D006801:Humans; D008023:Ligaments, Articular / Q000293:injuries* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D012540:Scapula; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000601:surgery; D013314:Stress, Mechanical; D013536:Suture Techniques; D013718:Tensile Strength