Abstract: There are described devices implantable in the human or animal body. Such a device takes the form of a pre-formed three-dimensional article, comprising at least in part a material which is hydratable and capable of bonding to tissue whilst retaining its integrity. The material may be activated, leading to cross-linking of the material and the formation of chemical bonds between the material and tissue to which it is applied. In preferred embodiments the material has self-adhesive properties. The article may have a wide variety of shapes to suit its intended purpose, and may be manufactured by a variety of methods.