The prosthesis has a tibial part (1) comprising an anchoring portion (2) to be inserted in a tibia, and a tibial plateau (3) arranged at an end of the portion. An anchoring portion (11) of a femoral part (10) is inserted in a femur. A connection unit (20) connects the femoral part with the tibial part. The femoral part is articulated on a core (21) of the connection unit, and a pivot is inserted in the tibial part. The core and the pivot form two distinct parts that are connected with each other when the tibial part is placed on the tibia and the femoral part is placed on the femur.
