THE REGENERATION OF ARTICULAR-CARTILAGE USING A NEW POLYMER SYSTEM

A polymer system based on room temperature polymerising poly(ethylmethacrylate) polymer powder and tetrahydrofurfuryl monomer has been investigated as a biomaterial for encouraging articular cartilage repair. This heterocyclic methacrylate polymer system swells slightly in situ and thus provides a good interface with subchondral bone resulting in mechanical stability with favourable uptake kinetics. Another feature of this polymer system is that it exhibits high water uptake which leads to absorption of the surrounding tissue fluid and matrix proteins, including growth factors; this may encourage the formation of new cartilage. Three weeks after implantation the tissue overgrowth contained cartilage components: chondrocytes, collagen type II, chondroitin 4-sulphate and chondroitin 6-sulphate. In addition numerous chondrocyte clones were observed at the edge of the defect and in the newly repaired tissue. By six weeks a superficial articulating surface was continuous with the normal articular cartilage with underlying tissue which showed some evidence of endochondral ossification. By nine weeks the surface covering of new cartilage had a widened and an irregular zone of calcified cartilage with thickened subchondral bone was present. At eight months the resurfaced cartilage remained intact above a remodelled subchondral bone end plate.