Dampener system for a posterior stabilization system with a fixed length elongated member

Dynamic posterior stabilization systems are described. A dynamic posterior stabilization system may include bone fasteners and a dampener system. The dampener system may include a fixed length elongated member. The dampener system may also include one or more dampener sets. The dampener sets may provide resistance to movement of vertebrae coupled to the dynamic posterior stabilization system. In some embodiments, the elongated member has at least two portions having different diameters. The different portions interact with other portions of the dampener system to allow for compression of a dampener set. In some embodiments, the dampener system includes a sleeve coupled to the elongated member. In some embodiments, the dampener system includes a pair of washers coupled to the elongated member. The sleeve or the pair of washers allow the dampener system to be secured to a bone fastener.