The Bone–Cartilage Interface - Structural Interfaces and Attachments in Biology - page 88

Fig. 5.1 Schematic
representation of normal
histology for the
osteochondral interface
region of synovial ( top panel )
and cartilaginous ( bottom
panel ) joints (adapted, with
permission, from [ 37 ] and
[ 42 ], respectively). In both
joint types, collagen fibrils in
the hyaline cartilage (HC)
become mineralized and
anchor the soft tissue to the
underlying bone. This ZCC
(zone of calcified cartilage) is
demarcated by wavy
tidemarks and contains
chondrocytes that may
regulate mineralization. The
ZCC is interlocked with the
underlying SCB (subchondral
bone) ( white ), where the
border is marked by a
tortuous cement line ( black ).
DZ deep, RZ radial, and STZ
superficial tangential zones of
HC, AF annulus fibrosus, NP
nucleus pulposis, BV blood
vessel, and M marrow space
known regarding how bone and cartilage are integrated in order to facilitate the
normal mechanical function of the ostechondral interface. This chapter also
considers how functionality is disrupted with aging, altered mechanical loading,
and disease. Improvements in our understanding, through a review of the existing
literature and identification of lingering questions, will enable better design of
tissue engineered osteochondral materials and improve our ability to robustly
integrate hard and soft engineered materials.
5.2 Morphological Foundations of the Bone-Cartilage Interface
The osteochondral unit forms an interface between the highly dissimilar materials
of soft, non-mineralized cartilage and the underlying stiff bone. This region forms a
layered structure that includes three distinct entities (Fig. 5.1 ): subchondral bone
(SCB), calcified cartilage, and soft hyaline cartilage. In the osteochondral interface
within the spinal tissues, the hyaline cartilage further joins the underlying bone with
an additional layer of fibrocartilage (i.e., the annulus fibrosus). The physical