The present invention relates to a knee joint prosthesis (1) having: a tibial component (2) and a femoral component (3). The tibial component (2) includes a fixation portion (10) adapted to be fixed to an upper end of a prepared tibia (T) in a patient, and a ceramic bearing portion (30) presenting at least one articulation surface (32). The femoral component (3) is adapted to be fixed to a lower end of a prepared femur (F) in a patient, and comprises a ceramic body portion (50) presenting at least one articulation surface (56) for engagement with the respective articulation surface(s) of the tibial component (2). The articulation surfaces (32, 56) of the tibial and femoral components (2, 3) are configured for essentially congruent engagement over a full range of movement of the prosthesis, and the bearing portion (30) of the tibial component (2) is adapted for movement relative to the fixation portion (10). The invention also provides a method of finishing articulation surfaces (32, 56) of ceramic components of a knee joint prosthesis, including the steps of combining the ceramic bearing portion (30) and the ceramic body portion (50) such that respective articulation surfaces (32, 56) are brought into engagement with a working substance (S) provided between them; and imparting relative movement to the bearing portion (30) and/or the body portion (50) such that the articulation surfaces (32, 56) repeatedly slide over one another, whereby friction forces generated between the articulation surfaces (32, 56) and the working substance (S) act to finish the surfaces simultaneously.