Hydrogel devices for surgical implantation to replace damaged cartilage in a mammalian joint (such as a knee, hip, shoulder, etc.) are disclosed, with one or more of the following enhancements: (1) articulating surfaces that have been given negative surface charge densities that emulate natural cartilage and that interact with positively charged components of synovial fluid； (2) anchoring systems with affixed pegs that will lock into accommodating receptacles, which will be anchored into hard bone before the implant is inserted into a joint； (3) a three-dimensional reinforcing mesh made of strong but flexible fibers, embedded within at least a portion of the hydrogel.
