A functionally dynamic stabilization unit (10) and
system for treatment of spinal
instability are provided. Each unit, and collectively, the
system, is configured to control flexion, extension and translation of the affected unstable vertebral area, thereby stabilizing the vertebral segments by restoring normal function. This is achieved by providing a unit and
system that allow for
lateral bending,
axial compression, rotation, anterior segmental height adjustment, and posterior segmental height adjustment. The unit and system provide sufficient segmental stiffness, while also limiting, or controlling, the
range of motion (i.e., sufficient stiffness in the neutral or
active zone, while limiting or preventing motion outside of the
active zone) to stabilize the vertebral segments. In use, the system mimics the natural movement of the normal spine. Furthermore, the system includes a rigid, fusion-promoting coupler (20) configured for use in an
adjacent level, or as a substitute for the functionally dynamic unit. The
modularity of the system allows adjustment over time and easier revision
surgery, and is configured for minimally-invasive, delivery or implantation.