US Patent 7892257 Spring loaded, load sharing polyaxial pedicle screw assembly and method

An assembly and method thereof comprising a screw head comprising an expandable bulbous end; a fixator component configured for receiving the bulbous end of the screw head; a load sharing mechanism positioned in between the bulbous end of the screw head and the bone fixator component, wherein the load sharing mechanism provides tensile resistance to the screw head; a pin mounted in the screw head; and a blocker adapted to engage the screw head. The screw head comprises a slot configured for receiving a longitudinal member. The load sharing mechanism may comprise any of a wave washer, a collapsible hollow washer, a coiled spring, and a flexible washer. Furthermore, the load sharing mechanism may comprise a washer having an outer surface with a plurality of cutout portions configured therein.