Table 2 Zonal structure of hyaline articular cartilage: from the articulating surface down to the subchondral bone [6, 7]
From: Shear bioreactors stimulating chondrocyte regeneration, a systematic review
Zone | % | Collagen | Collagen alignment | Shape of cell | Proteoglycan | Property |
|---|---|---|---|---|---|---|
The superficial (tangential) | 10–20 | Small diameter, densely packed collagen fibers | Parallel to the cartilage | Flattened, discoidal shapes | Low proteoglycan | Low permeability |
The middle, or transitional | 40–60 | – | Arcade-like structure | Spherical in shape | Reaches its maximum | – |
The deep zone/radial | 30% | Collagen large fibers | Perpendicular to the articular surface | Columnar organization. elongated | Proteoglycan much lower than in the middle zone | “Tidemark” |
The calcified zone | – | – | – | – | – | transitions into the subchondral bone |