Prostheses, systems, and methods are provided for replacement of natural
facet joints between adjacent vertebrae using polyaxial attachment mechanisms for securing the prostheses to the vertebrae. A cephalad
prosthesis attached to a superior adjacent
vertebra replaces the inferior half of a natural
facet joint. A caudal
prosthesis attached to an inferior adjacent
vertebra replaces the superior half of a natural
facet joint. Both the cephalad and caudal prostheses are configured with artificial
facet joint structures that include articulating surfaces that cooperate and form an artificial articular configuration. The polyaxial attachment mechanism permits adjustment of the position of the artificial
facet joint structure along more than one axis at or after the time the cephalad or caudal
prosthesis is attached to a
vertebra.