The Bone–Cartilage Interface - Structural Interfaces and Attachments in Biology - page 101

Fig. 5.3 Deformation under compressive loading showing deformation in (a) healthy and
(b) degenerated cartilage. White dotted lines illustrate pattern of collagen fibril and chondrocyte
deformation. Degenerated and fibrillated cartilage in ( b ) is mechanically weaker and retains less
water (adapted, with permission, from [ 62 ])
of collagen fibrils forms a mutually supportive fibrous network that can bear more
load than many can individually.
Compressive forces applied to the surface of the hyaline cartilage translate into
deep shear forces through lateral movement of the radial zone's hyaline cartilage
(Fig. 5.3 ). Under compression, the high osmotic pressure matrix surrounding the
fibrils causes matrix stiffening and thus allows only small deformations of the collagen
fibrils. The bundled fibrils that continue into the ZCC allow deep zone collagen to
better resist lateral shear forces that result from compression of the superficial hyaline
articular surface [ 1 , 62 , 118 ]. Large deformations are not observed when simulating
physiological loading conditions; significant extension and movement of the collagen
fibrils would lead to abrasion and fatigue of the collagen and surrounding matrix
[ 1 , 140 ]. Small deformations of collagen fiber bundles that penetrate into the ZCC
likely transmit direct and repeated compressive and shear loads without loss of
structural integrity to tissues contained within the interface region [ 1 ].