Spinal stabilization device

Abstract

A connection unit for use in a spinal stabilization device, in one embodiment, includes a longitudinal member having first and second ends, and a flexible section disposed between the first and second ends, the flexible section having at least one groove formed therein, wherein the flexible section is characterized by a cross-sectional profile that is different from that of the first and second ends.

1 . A connection unit for use in a spinal stabilization device comprising a longitudinal member configured to be secured to a patient's spine using at least three securing members; wherein a first section of the longitudinal member, configured to be positioned between a first pair of securing members, exhibits greater flexibility than a second section of the longitudinal member, configured to be positioned between a second pair of securing members.  
     
     
         2 . The connection unit of  claim 1  wherein the longitudinal member is configured in the shape of a cylindrical rod.  
     
     
         3 . The connection unit of  claim 1  wherein the first section comprises at least one groove formed therein for providing flexibility to the first section.  
     
     
         4 . The connection unit of  claim 3  wherein the at least one groove is a spiral groove.  
     
     
         5 . The connection unit of  claim 3  wherein the at least one groove terminates on a strain relief hole of a larger diameter than the groove width.  
     
     
         6 . The connection unit of  claim 1  wherein the longitudinal member comprises a material selected from a group of known, bio-compatible materials consisting of metals, metal alloys, organic polymers, naturally occurring resins, thermoplastics, elastomers and composite materials.  
     
     
         7 . The connection unit of  claim 3  wherein the longitudinal member comprises a solid object.  
     
     
         8 . The connection unit of  claim 3  wherein the longitudinal member comprises a hollow object.  
     
     
         9 . The connection unit of  claim 3  wherein the longitudinal member comprises a hollow object of a first material that is at least partially filled with a second material, the second material comprising one of a group of known, bio-compatible materials consisting of organic polymers, naturally occurring resins, elastomers and composite materials.  
     
     
         10 . A connection unit for use in a spinal stabilization device comprising a longitudinal member comprising first and second ends, and a flexible section disposed between the first and second ends, the flexible section having at least one groove formed therein, wherein the flexible section is characterized by a cross-sectional profile that is different from that of the first and second ends.  
     
     
         11 . The connection unit of  claim 10  wherein the longitudinal member is configured in the shape of a cylindrical rod.  
     
     
         12 . The connection unit of  claim 10  wherein a cross-sectional profile of the flexible section is smaller than a cross sectional profile of at least one of the first or second ends, thereby providing increased flexibility to the flexible section.  
     
     
         13 . The connection unit of  claim 10  wherein the cross-sectional profile of the flexible section is greater than a cross sectional profile of at least one of the first or second ends.  
     
     
         14 . The connection unit of  claim 10  wherein the cross-sectional profile of the flexible section is tapered along a longitudinal axis of the flexible section such that a cross-sectional profile of the flexible section is smallest near a central portion of the flexible section and is largest at opposing transition sections between the flexible section and opposing first and second ends.  
     
     
         15 . The connection unit of  claim 10  wherein the longitudinal member comprises a first material selected from a group of known, bio-compatible materials consisting of metals, metal alloys, organic polymers, naturally occurring resins, thermoplastics, elastomers and composite materials.  
     
     
         16 . The connection unit of  claim 10 , wherein the flexible section comprises a hollow object of a first material that is filled with a second material, the second material comprising one of a group of known, bio-compatible materials consisting of organic polymers, naturally occurring resins, elastomers and composite materials.  
     
     
         17 . The connection unit of  claim 16  wherein the second material decreases the compressibility of the flexible section due to an applied load.  
     
     
         18 . The connection unit of  claim 16  wherein the second material is more flexible than the first material and increases the energy absorption of the flexible section for a given deflection.  
     
     
         19 . The connection unit of  claim 16 , wherein the second material has different flexibility from the first material, and the second material's cross-section is non-uniformly distributed along an axis of the longitudinal member to provide different flexibility in different bending directions.  
     
     
         20 . A connection unit for use in a spinal stabilization device comprising a longitudinal member having a longitudinal axis, first and second ends configured to be secured to a patient's spine using respective securing members, and a flexible section between the first and second ends, wherein the flexible section has at least one groove formed therein, and wherein at least one groove parameter varies along at least a portion of the longitudinal axis of the flexible section.  
     
     
         21 . The connection unit of  claim 20  wherein the longitudinal member is configured in the shape of a cylindrical rod.  
     
     
         22 . The connection unit of  claim 20  wherein the longitudinal member comprises a first material selected from a group of known, bio-compatible materials consisting of metals, metal alloys, organic polymers, naturally occurring resins, thermoplastics, elastomers and composite materials.  
     
     
         23 . The connection unit of  claim 20  wherein the at least one groove parameter comprises the width of the groove along the longitudinal axis of the connection unit.  
     
     
         24 . The connection unit of  claim 20  wherein the at least one groove parameter comprises a cross-sectional depth of the groove.  
     
     
         25 . The connection unit of  claim 20  wherein the at least one groove parameter comprises a groove-to-groove spacing.  
     
     
         26 . The connection unit of  claim 20  wherein the at least one groove comprises a circumferential spiral along the longitudinal axis.  
     
     
         27 . The connection unit of  claim 20  wherein the at least one groove comprises a first groove and a second groove, and wherein the first groove is not contiguous with the second groove.  
     
     
         28 . The connection unit of  claim 20  wherein the at least one groove terminates on a strain relief hole of a larger diameter than the groove width.  
     
     
         29 . A connection unit of a first material for use in a spinal stabilization device comprising a longitudinal member having first and second ends, configured to be secured to a patient's spine using respective securing members, and a flexible section in between the first and second ends wherein at least part of the flexible section is clad with a cladding of a second material.  
     
     
         30 . The connection unit of  claim 29  wherein the longitudinal member is configured in the shape of a cylindrical rod.  
     
     
         31 . The connection unit of  claim 29  wherein the first material comprises a material selected from a group of known bio-compatible materials consisting of metals, metal alloys, organic polymers, naturally occurring resins, thermoplastics, elastomers and composite materials.  
     
     
         32 . The connection unit of  claim 29  wherein the second material comprises a material selected from a group of known bio-compatible materials consisting of organic polymers, elastomers, naturally occurring resins, and composite materials.  
     
     
         33 . The connection unit of  claim 29  wherein the cladding is injection molded around the longitudinal member.  
     
     
         34 . The connection unit of  claim 29  wherein the cladding is applied to the longitudinal member by dipping the longitudinal member.  
     
     
         35 . The connection unit of  claim 29  wherein the cladding is applied to the longitudinal member by spraying the longitudinal member.  
     
     
         36 . The connection unit of  claim 29  wherein the cladding is applied to the longitudinal member with a mechanical applicator.  
     
     
         37 . The connection unit of  claim 29  wherein the cladding is a separately manufactured part that is conformable with a central section of modified flexibility, and is assembled with the longitudinal member.  
     
     
         38 . A connection unit for use in a spinal stabilization device comprising a longitudinal member having first and second ends, with a flexible section disposed in between the first and second ends, wherein at least one of the first or second ends is of a sufficient length to accommodate a range of positions for coupling to a securing member.  
     
     
         39 . The connection unit of  claim 38  wherein the longitudinal member is configured in the shape of a cylindrical rod.  
     
     
         40 . The connection unit of  claim 38  wherein the at least one end may be cut to length to remove a length of material that extends beyond a securing member.  
     
     
         41 . The connection unit of  claim 38  wherein only one end is of sufficient length to accommodate a range of positions for coupling to a securing member, such that a wide range of positions for coupling to a securing member may be achieved with a connection unit of one size with no more than one operation to cut the connection unit to length.  
     
     
         42 . The connection unit of  claim 38  wherein the flexible section comprises at least one groove.  
     
     
         43 . The connection unit of  claim 38  wherein the groove is a spiral groove.  
     
     
         44 . The connection unit of  claim 38  wherein the longitudinal member comprises a material selected from a group of known bio-compatible materials consisting of metals, metal alloys, organic polymers, naturally occurring resins, thermoplastics, elastomers and composite materials.