Hydroswellable, non-absorbable, biostable, segmented, aliphatic polyether-urethane-ureas or polyether-siloxane-urethane-ureas form a single component, intra-articular device for restoring joints with artificial cartilage, as a cartilage substitute for degenerated cartilage and/or for enhancing the remaining cartilage of an arthritic joint. The intra-articular devices can be bicomponent in nature comprising a biostable, articulating, non-absorbable component and an absorbable component in the form of a solid or microporous liner interfacing with the tissue of defective or diseased joint to support in situ tissue engineering. One or more bioactive agent with specific pharmacological function can be incorporated in the single or bicomponent intra-articular devices to supplement their structural functions.