Effects of region and sex on the mechanical properties of the glenohumeral capsule during uniaxial extension.

Surgical repair of the glenohumeral capsule after dislocation ignores regional boundaries of the capsule and is not sex specific. However, each region of the capsule functions to stabilize the joint in different positions, and differences in joint laxity between men and women have been found. The objectives of this research were to determine the effects of region (axillary pouch and posterior capsule) and sex on the material properties of the glenohumeral capsule.

Material properties of the axillary pouch of the glenohumeral capsule: is isotropic material symmetry appropriate?

Inconclusive findings regarding the collagen fiber architecture and the material properties of the glenohumeral capsule make it unclear whether the material symmetry of the glenohumeral capsule is isotropic or anisotropic. The overall objective of this work was to use a combined experimental and computational protocol to characterize the mechanical properties of the axillary pouch of the glenohumeral capsule and to determine the appropriate material symmetry. Two perpendicular tensile and finite simple shear deformations were applied to a series of tissue samples from the axillary pouch of the glenohumeral capsule.

The current anatomical description of the inferior glenohumeral ligament does not correlate with its functional role in positions of external rotation.

The objective of this study was to determine the strain distribution in the inferior glenohumeral ligament at 0 degree, 30 degrees, and 60 degrees of external rotation with an anterior load applied to the joint. Five cadaver shoulders were dissected free of all soft tissue except the glenohumeral capsule and a 7 x 11 grid of strain markers were affixed to the inferior glenohumeral ligament. The location of these strain markers was then determined for a reference strain configuration and while a 25 N anterior load was applied to simulate a clinical exam for instability.