Articular Cartilage

Articular cartilage is a layer of tissue that covers the ends of apposing long bones in our joints. This layer permits the almost friction-free movement of the bony ends against each other. Articular cartilage is highly prone to injury and pathological degeneration. If the structural lesions thereby generated are confined to the articular cartilage layer itself, they not only fail to heal spontaneously but progressively enlarge with time.

If the lesions extend through the articular cartilage layer into the underlying sanginous bone, then a spontaneous healing response is set in train. But the tissue formed is structurally and mechanically inferior to native articular cartilage, and it does not persist. Cartilage repair aims at treating these lesions so as to induce the regeneration of tissue with native properties.

The surgical therapies currently implemented are diverse in nature. But, as yet, no truly effective strategy has been elaborated. The most promising approaches involve the introduction of a defect-filling matrix containing either cartilage precursor cells or signalling substances that will induce their local recruitment. The underlying principle of these strategies is that the cartilage precursor cells (transplanted or locally recruited) will differentiate into cartilage-producing chondrocytes. Most of these cartilage-engineering strategies are still at an experimental stage of development; they are not yet ripe for clinical application.