The Bone–Cartilage Interface - Structural Interfaces and Attachments in Biology - page 89

Fig. 5.2 Calibrated backscattered electron image of the osteochondral region in rabbit tissue
showing the HC ¼ hyaline articular cartilage, ZCC, and SCB, where the absence of mineral
density in the HC is shown as black ( gray level ¼ 0) and mineralized regions in shades of gray to
white (up to gray level ¼ 255). Wavy tidemarks indicate regions of HC that are permeated with
mineral; a white tortuous cement line ( arrows ) marks the boundary where the ZCC is anchored to
the underlying SCB. Asterisks denote regions where ZCC and/or SCB has been removed by
osteoclasts and infilled with newly formed bone by osteoblasts. O ¼ example of an osteon that
surround a central Haversian canal where blood vessels reside. M ¼ marrow space within
subchondral trabecular bone structure. The mineralized ZCC shows a smooth appearance as
compared to the greater texture of mineral within the SCB
interaction between the osteochondral components creates a robust, continuous
connection between materials possessing dissimilar properties. This section
explores how this region both facilitates and presents challenges for the anchoring
of cartilage to bone and synthesizing biomimetic biomaterial systems.
Like most biological tissues [ 36 ], the bone-cartilage interface possesses a hierar-
chy that spans multiple length scales. In humans, the joint as a whole is a macro-
scopic structure that may be up to centimeters thick where the cartilage anchors to
the underlying SCB via the ZCC: an intermediate, thin layer of mineralized, or
calcified, cartilage. The tissues that span this interfacial region are each formed from
similar constituent phases, yet are differentially organized at the tissue-level, where
the microstructural arrangement contributes to the unique function performed by
each tissue. The cell populations in these tissues also vary and are differentially
responsive to mechanical loads, disease, and therapeutics for treatment of bone or
cartilage disorders.