Abstract: A surgical instrument is provided for urging a longitudinal spinal member into a bone fastener. The surgical instrument may include a holder assembly for engaging a bone fastener, the holder assembly preferably comprising a pair of pivotably connected members arranged in a scissor type configuration, and a reducing mechanism for moving the spinal rod with respect to the bone fastener, the reducing mechanism including a rod contacting member and an outer support structure having an opening for receiving at least a portion of the holder assembly and a cavity for receiving at least a portion of the vertical drive mechanism which is sized and configured to threadably engage the holder assembly. The holder assembly preferably includes a pair of jaws each having an extension formed thereon for engaging a recess formed on the lateral side walls of the bone fastener so that the holder assembly can engage the bone fastener without extending into the U-shaped channel.

Abstract: A motion interface structure for use with a pedicle screw is provided, the motion interface structure defining a central passage having an internal face. A helical thread is formed on at least a portion of the internal face of the central passage. The motion interface element is designed to cooperate with an upstanding region of a pedicle screw. The upstanding region includes a threaded region that is adapted to threadingly engage the helical thread associated with the motion interface element. The motion interface element may take the form of a spherical element or a universal joint mechanism. The pedicle screw and motion interface element may be incorporated into a spinal stabilization system that includes one or more additional pedicle screw/motion interface element subassemblies. The spinal stabilization system may also include a dynamic stabilizing element that provides clinically efficacious results.

Abstract: A pedicle screw assembly is provided that includes a pedicle screw and a preloaded set screw. The set screw is preloaded in a threaded, central aperture formed in the head region of the pedicle screw. An interference is advantageously formed on the set screw to prevent dislodgement of the set screw, e.g., during shipment and/or clinical placement of the pedicle screw. An upwardly extending collet is generally formed in the head region of the pedicle screw, the collet being sized to receive a spherical element therearound. Advancement of the set screw relative to the pedicle screw secures the spherical element relative to the pedicle screw. The spherical element typically includes a socket member that cooperates with a dynamic stabilizing member. The pedicle screw assembly and dynamic stabilizing member are advantageously used as part of a spinal stabilization system to provide clinically efficacious results.

Abstract: A pedicle screw is provided that includes an upwardly extending collet. The collet may include downwardly extending slots that define deflectable segments therebetween. When a spherical element or other structure, e.g., a non-dynamic stabilizing element, is positioned around the collet, introduction of a set screw causes outward deflection of the upstanding segments into engagement with the spherical element. A snap ring may be interposed between the collet and the spherical element to facilitate positioning therebetween. In an alternative embodiment, a non-slotted collet is employed. In such embodiment, the collet and the spherical element may be threadingly engaged and may include a snap ring therebetween. The pedicle screw subassemblies may be incorporated into a spinal stabilization system which may include a dynamic stabilizing member to provide clinically efficacious results.

Abstract: A prosthetic nucleus pulposus for replacing the natural nucleus pulposus of an intervertebral disc. The prosthetic nucleus proposus comprises a partially collapsed sealed envelope formed from a material which is permeable to extracellular body fluid. The envelope contains a solute which provides an osmotic potential across the walls of the envelope. In use, the partially collapsed envelope is surgically implanted in the hallowed-out interior of an intervertebral disc and is allowed to absorb fluid, whereby expansion of the envelope and subsequent disc expansion is accomplished.