Pedicle screw extension for use in percutaneous spinal fixation

• US 9,433,446 B2
• Filed: 09/23/2014
• Issued: 09/06/2016
• Est. Priority Date: 06/18/2010
• Status: Active Grant

• Current Assignee: Spine Wave Incorporated
• Original Assignee: Spine Wave Incorporated
• Inventors: McLean, Scott, Seyer, Steven
• Primary Examiner(s): Robert, Eduardo C
• Assistant Examiner(s): ECKMAN, MICHELLE CHRISTINE
• Application Number:
  US14/493,453
• Publication Number:
  US 20150012049A1
• Time in Patent Office: 714 Days
• Field of Search: 606246-279, 606/86.A, 606/99, 606/104, 606300-305
• US Class Current: 1/1
• CPC Class Codes: A61B 17/7002 Longitudinal elements, e.g. rods
• CPC Class Codes: A61B 17/7004 with a cross-section which varies along its length A61B17/7019 takes precedence
• CPC Class Codes: A61B 17/7011 Longitudinal element being non-straight, e.g. curved, angled or branched adjustable length longitudinal elements A61B17/7014; A61B17/7019 takes precedence, e.g. coil springs
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7034 characterised by a lateral opening
• CPC Class Codes: A61B 17/7035 Screws or hooks, wherein a rod-clamping part and a bone-anchoring part can pivot relative to each other
• CPC Class Codes: A61B 17/7037 wherein pivoting is blocked when the rod is clamped
• CPC Class Codes: A61B 17/7076 for driving, positioning or assembling spinal clamps or bone anchors specially adapted for spinal fixation
• CPC Class Codes: A61B 17/7077 for moving bone anchors attached to vertebrae, thereby displacing the vertebrae
• CPC Class Codes: A61B 17/7079 Tools requiring anchors to be already mounted on an implanted longitudinal or transverse element, e.g. where said element guides the anchor motion
• CPC Class Codes: A61B 17/7082 for driving, i.e. rotating, screws or screw parts specially adapted for spinal fixation, e.g. for driving polyaxial or tulip-headed screws driving other bone screws A61B17/8875
• CPC Class Codes: A61B 17/7083 Tools for guidance or insertion of tethers, rod-to-anchor connectors, rod-to-rod connectors, or longitudinal elements
• CPC Class Codes: A61B 17/7085 for insertion of a longitudinal element down one or more hollow screw or hook extensions, i.e. at least a part of the element within an extension has a component of movement parallel to the extension's axis
• CPC Class Codes: A61B 17/7086 Rod reducers, i.e. devices providing a mechanical advantage to allow a user to force a rod into or onto an anchor head other than by means of a rod-to-bone anchor locking element; rod removers
• CPC Class Codes: A61B 17/8875 Screwdrivers, spanners or wrenches

Abstract

A bone screw extension assembly for use in placing a connecting rod percutaneously into tissue of a patient comprises a multi-axial bone screw and a screw extension releasably coupled to yoke of the bone screw. The screw extension includes coaxially disposed outer sleeve and inner sleeves that are rotatable relative to each other. A screw engaging member projects radially from the distal end of the inner sleeve and is configured to engage an extension coupling surface on the outer sleeve upon relative rotation of the inner and outer sleeves. A securement member including cooperative surfaces is defined adjacent the distal end of the inner and outer sleeves that is operable upon relative rotation of the inner sleeve and outer sleeve to radially secure the sleeves together to thereby maintain the engagement of the screw engaging member and the bone screw.

Claims

1. An anchor extension for releasably coupling to a spinal bone anchor comprising:

an elongate hollow outer sleeve having a distal end, a proximal end, and a perimetric sidewall defining a bore through said distal and proximal ends, an interlocking engagement surface defined adjacent the distal end of said outer sleeve, and a pair of opposing slots formed through said sidewall, each slot opening through the distalmost edge of said outer sleeve and extending for a length proximally of said interlocking engagement surface;

an elongate hollow inner sleeve disposed within the bore of said outer sleeve and having a distal end, a proximal end, and a perimetric sidewall defining a bore through said distal and proximal ends, a cooperative interlocking engagement surface defined adjacent the distal end of said inner sleeve, and a pair of opposing slots formed through said sidewall, each slot opening through the distalmost end of said inner sleeve and extending for a length proximally of said cooperative interlocking engagement surface, said outer sleeve and said inner sleeve being movable rotationally relative to each other such that the slots of said inner sleeve are aligned with the slots of said outer sleeve without the perimetric sidewall of the distal end of said outer sleeve extending across the slots of said inner sleeve; and

an anchor engaging member projecting radially from the distal end of one of said outer sleeve and said inner sleeve for engaging the bone anchor upon relative rotation of said inner sleeve and said outer sleeve, said anchor engaging member being separate from and more distally of each of said interlocking engagement surface and said cooperative interlocking engagement surface,

wherein said interlocking engagement surface and said cooperative interlocking engagement surface are operable upon relative rotation of said inner sleeve and said outer sleeve to directly interlock cooperatively with each other and thereby radially secure said inner sleeve and said outer sleeve together against radial movement for maintaining the engagement of said screw engaging member and said bone screw with said slots of said inner sleeve and said outer sleeve being in alignment.

2. The anchor extension of claim 1, wherein said anchor engaging member is disposed on said inner sleeve and projects radially outwardly therefrom.

3. The anchor extension of claim 2, wherein:

the cooperative interlocking engagement surface on said inner sleeve includes a flange extending radially outwardly from said inner sleeve; and

the interlocking engagement surface on said outer sleeve is defined by a groove extending into an inner surface of said outer sleeve.

4. The anchor extension of claim 3, wherein:

said flange includes a portion projecting toward the distal end of said inner sleeve; and

said groove opens upwardly toward the proximal end of said outer sleeve and is configured to receive said distally projecting portion of said flange.

5. In combination for use during spinal surgery,

a multi-axial bone screw including a shaft having a threaded screw portion, a screw head and a yoke articulatingly attached to said screw head, said yoke having an exterior surface and a slot therethrough for receiving a connecting rod, said slot defined by a pair of upstanding arms having opposed interior surfaces, said yoke having an extension coupling surface thereon;

an elongate hollow screw extension having a distal end and a proximal end, the extension including a screw engaging member at the distal end thereof in engagement with said extension coupling surface on said yoke, said extension having a pair of opposing extension slots opening at the distal edge of said extension aligned with and without the distal end of said screw extension extending across said yoke slot, said pair of slots each extending for an extent toward the proximal end of said extension, said extension including a persuader coupling member at a location more proximal than said slots; and

a rod persuader including an elongate member releasably coupled to said persuader coupling member for axial but not rotational movement relative to said screw extension independently of and without affecting the engagement of said screw engaging member of said extension with the extension coupling surface on said yoke, said persuader member having a distal end defining an axially movable rod engaging surface disposed in a first axial position to allow a rod to be introduced through the opposing slots in said screw extension and operably movable relative to said persuader coupling member to a second axial position wherein said rod engaging surface lies adjacent to the distal end of said extension to urge said rod into the slot of said yoke, said rod persuader elongate member including thereon a coupling element releasably coupled directly to said persuader coupling member, said coupling element being configured to couple to and decouple from said persuader coupling member to allow said rod persuader elongate member to be releasably mounted on and withdrawn from said extension while said extension is in engagement with said yoke.

6. The combination of claim 5, wherein said persuader coupling member is located adjacent said proximal end of said elongate hollow screw extension.

7. The combination of claim 5, wherein said coupling element and said persuader coupling member form a rack and pinion arrangement.

8. The combination of claim 7, wherein said coupling element is defined by a pinion gear and said persuader coupling member defines a rack.

9. In combination for use during spinal surgery,

a multi-axial bone screw including a shaft having a threaded screw portion, a screw head and a yoke articulatingly attached to said screw head, said yoke having an exterior surface and a slot therethrough for receiving a connecting rod, said slot defined by a pair of upstanding arms having opposed interior surfaces, said yoke having an extension coupling surface thereon;

an elongate hollow screw extension having a distal end and a proximal end, the extension including a screw engaging member at the distal end thereof in engagement with said extension coupling surface on said yoke, said extension having a pair of opposing extension slots opening at the distal end of said extension aligned with said yoke slot and extending for an extent toward the proximal end of said extension, said extension including a persuader coupling member more proximal than said slots; and

a rod persuader including an elongate member releasably coupled to said persuader coupling member for axial movement relative to said screw extension independently of and without affecting the engagement of said screw engaging member of said extension with the extension coupling surface on said yoke, said persuader member having a distal end defining an axially movable rod engaging surface disposed in a first axial position to allow a rod to be introduced through the opposing slots in said screw extension and operably movable in cooperation with said persuader coupling member to a second axial position wherein said rod engaging surface lies adjacent to the distal end of said extension to urge said rod into the slot of said yoke, said rod persuader elongate member including thereon a coupling element releasably coupled directly to said persuader coupling member, said coupling element being configured to couple to and decouple from said persuader coupling member to allow said rod persuader elongate member to be releasably mounted on and withdrawn from said extension while said extension is in engagement with said yoke, said rod persuader elongate member including an advancement mechanism driven by a rotatable lever, said rod persuader elongate member being operably coupled to said lever for axial movement of said rod persuader member relative to said screw extension upon rotation of said lever.

10. The combination of claim 9, wherein said advancement mechanism further includes a locking mechanism operable to lock said coupling element to said coupling member and thereby rod persuader member in a fixed position.