There is provided a posterior lumbar joint prosthesis which includes prosthetic elements reproducing the movements of the joint facets and vertebral anchors which adapt to the variations in the anatomy of vertebra. In use, the prosthesis has lower and upper connectors on each side of the lumbar vertebra. The lower connectors are coupled with, and pivotably mounted onto, respective lower pedicular screws, and a member defining a member axis links lower and upper connectors on each side of the lumbar vertebra. Upon lateral flexion of one of the upper and lower vertebrae relative to the other, each lower connector is capable of multiaxis pivotable movement relative to the respective lower pedicular screws such that each member is capable to pivot with respect to (i) the axis of the lower screw, (ii) a first axis intersecting the lower screw and the lower connector, and/or (iii) an axis intersecting the above first axis and the lower screw, while the member can also move along the member axis.