A prosthesis for articulation (e.g., hip or joint prosthesis) is provided,
which includes a pair of articulation components respectively defining a
pair of articulation surfaces movably engageable with each other. In some
embodiments, each of the articulation surfaces is formed from a
biocompatible ceramic (e.g., doped silicon nitride ceramic) having a
flexural strength greater than about 700 Mega-Pascal (MPa) and a
toughness greater than about 7 Mega-Pascal root meter (MPam.sup.0.5).