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US-20260123963-A1 - BONE ANCHOR EXTENDED TAB BRIDGE CUTTING AND TAB BREAKING INSTRUMENT

US20260123963A1US 20260123963 A1US20260123963 A1US 20260123963A1US-20260123963-A1

Abstract

An instrument and method for cutting a pair of bridges connecting opposing extended tabs of a spinal bone anchor yoke receiver. The instrument includes a pair of opposing movable handles pivotally coupled to each other and a pair of opposing movable legs respectively at the distal end of the handles, each leg supporting a cutting blade facing the other cutting blade. A pair of anvil surfaces is disposed between the cutting blades and spaced therefrom for receipt of a respective bridge. Movement of the handles causes each cutting blade to move toward an anvil surface and compress a respective bridge between a respective cutting blade and an anvil surface until each bridge is severed. The method includes attaching the instrument to at least one of the extended tabs, cutting the bridges, and manipulating the instrument back and forth to remove the one extended tab from the yoke receiver.

Inventors

  • Eugene Avidano
  • David Boisvert
  • Andrea Wright

Assignees

  • SPINE WAVE, INC.

Dates

Publication Date
20260507
Application Date
20251027

Claims (20)

  1. 1 . An instrument for cutting a pair of bridges connecting a pair of opposing extended tabs extending from a yoke receiver of a spinal bone anchor, said opposing extended tabs defining a slot therebetween for receipt of a spinal rod, said instrument comprising: a pair of opposing movable handles pivotally coupled to each other, said handles each having a proximal end and a distal end: a pair of opposing movable legs, one leg each being pivotally coupled to a respective handle at its distal end thereof; a pair of cutting blades, one blade being supported on each of said legs in facing relation to the other cutting blade; and a guide pin supported by said legs and disposed between said cutting blades, said guide pin including a pair of anvil surfaces, each one of said anvil surfaces facing a respective one of said cutting blades and spaced therefrom for receipt of a respective bridge, wherein movement of said handles causes each of said cutting blades to move toward said guide pin and compress a respective bridge between a respective cutting blade and an anvil surface until each bridge is severed.
  2. 2 . The instrument of claim 1 , wherein a support plate is attached to each leg in a manner to allow relative movement of said legs toward and away from each other.
  3. 3 . The instrument of claim 2 , wherein said support plate has an outwardly curved inner surface facing said guide pin, said curved inner surface having a radius of curvature slightly larger than a radius of curvature of an outer surface of one of said extended tabs to define a space therebetween for receipt of said one extended tab.
  4. 4 . The instrument of claim 3 , wherein said guide pin is movable linearly relative to said legs in a direction toward and away from said handles.
  5. 5 . The instrument of claim 4 , wherein said support plate includes a vertically extending elongated rail, and wherein said guide pin has an elongated vertically extending slot sized and configured for linear movable receipt of said rail.
  6. 6 . The instrument of claim 5 , wherein said guide pin includes a pair of outwardly projecting curved surfaces on opposite sides of guide pin adjacent said elongated slot, and wherein each leg comprises an inwardly directed curved surface more proximal than said cutting blades for receipt therein of said outwardly projecting curved surfaces of guide pin.
  7. 7 . The instrument of claim 6 , wherein said inwardly directed curved surfaces each have a radius of curvature slightly larger than a radius of curvature of said outwardly projecting curved surfaces to allow slight linear movement of said guide pin between said legs.
  8. 8 . The instrument of claim 7 , wherein each of said anvil surfaces is defined by elongated edges projecting outwardly from opposite sides of said guide pin.
  9. 9 . The instrument of claim 8 , wherein said guide pin further includes a pair of alignment pins more proximal than and on opposite sides of elongated edges.
  10. 10 . The instrument of claim 9 , wherein said guide pin further includes an outwardly projecting flange between said elongated slot and said alignment pins that defines a stop surface that is sized and configured to abut a proximal end of said extended tabs to position said cutting blades in juxtaposition with said respective bridges.
  11. 11 . The instrument of claim 10 , wherein said guide pin has an outer diameter more distal than said alignment pins that approximates an inner diameter defined by said opposing extended tabs.
  12. 12 . The instrument of claim 11 , further including a spring disposed between said handles to bias said handles so that said cutting blades are in a normally open position.
  13. 13 . A method of cutting a pair of bridges connecting a pair of opposing extended tabs extending from a yoke receiver of a spinal bone anchor, said bridges being disposed at a proximal end of said extended tabs, and for breaking off said extended tabs from said spinal bone anchor that are connected to said yoke receiver by frangible connectors at a distal end of said extended tabs, comprising the steps of: attaching an instrument to at least one of said extended tabs, said instrument comprising an operable pair of opposing cutting blades; operating said cutting blades to cut both of said bridges to thereby separate said extended tabs from each other at said proximal end; and with said instrument remaining attached to said one extended tab manipulating said instrument back and forth until said one extended tab is removed from said yoke receiver.
  14. 14 . The method of claim 13 , wherein during said manipulating step, the method further includes the step of engaging said opposing extended tabs with said instrument to weaken the frangible connector attaching said opposing extended tab to said yoke receiver to thereby allow manual removal of said opposing extended tab.
  15. 15 . The method of claim 13 , including the step of providing said instrument with a pair of anvil surfaces opposing said cutting blades, and placing said instrument on said one extended tab such that each of said bridges is respectfully placed between a cutting blade and an anvil surface.
  16. 16 . The method of claim 15 , wherein said instrument is placed onto the proximal ends of said extended tabs with said cutting blades being located in juxtaposition exteriorly of said bridges and said anvil surfaces being located in juxtaposition interiorly of said bridges.
  17. 17 . The method of claim 16 , wherein said operating step is practiced by moving said cutting blades toward each of said respective bridges to compress said bridges between said respective anvil surfaces and said cutting blades until said bridges are severed.
  18. 18 . The method of claim 17 , wherein said instrument comprises a stop surface for engaging the proximal ends of said extended tabs, and wherein during the attachment step said stop surface is placed in an engagement with said proximal ends to place said anvil surfaces and said cutting blades in axial juxtaposition with said bridges.
  19. 19 . The method of claim 18 , wherein said instrument comprises alignment pins, and wherein said alignment pins are placed during the attachment step of said instrument onto said extended tabs to radially align said cutting blades and said anvil surfaces with said bridges.
  20. 20 . The method of claim 19 , wherein said instrument comprises a guide pin that is supported between said cutting blades, said guide pin including said stop surface said alignment pins, and wherein said instrument further includes a support plate spaced from said guide pin to define a space therebetween, and wherein during the attachment step said one extended tab is placed into said space.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63/715,739, filed Nov. 4, 2024, the entire contents of which are incorporated by reference herein. FIELD OF THE INVENTION The subject invention relates generally to the field of instruments used in spinal surgery, and more particularly, to an instrument for cutting a bridge joining bone anchor extended tabs and for breaking off one or more extended tabs from the bone anchor upon attachment to a spinal fixation rod. BACKGROUND OF THE INVENTION Spinal fixation devices are commonly used in spinal surgery to hold one or more vertebral motion segments in a fixed position to allow fusion or healing. Such fixation devices commonly include a rigid spinal rod that is joined to adjacent vertebral bodies by attaching the rod to bone anchoring devices, such as hooks and/or bone screws. Bone screws, known as pedicle screws for example, may be configured to be inserted into a pedicle of a vertebral body for securing the spinal rod in the fixation construct. Such pedicle screws typically comprise a threaded shank for threaded engagement into a pedicle of a vertebral body, and a yoke attached to a head of the threaded shank for receiving a spinal fixation rod. In some instances, the yoke may be polyaxially coupled to the head of the threaded shank, either before or after the threaded shank is introduced into the pedicle. The yoke typically includes a pair of spaced arms defining a U-shaped channel for receipt of the spinal rod. A fastening mechanism, such as a set screw, is commonly used to lock the spinal rod into the receiving channel of the yoke. With the advent of minimally invasive and percutaneous spinal surgery, a need has developed for the placement of spinal implants, including pedicle screws and fixation rods, though one or more small incisions formed through the skin of the patient from a position outside the patient. This has resulted in the addition of extended tabs that are breakably attached at their distal ends to the respective arms of the yoke, with the extended tabs being of length such that the proximal ends extend through the skin surface of the patient for access by the surgeon. Such extended tabs are commonly attached to the yoke arms at a frangible portion that is configured to break under a predetermined force so that the extended tabs may be separated from the yoke upon completion of the surgery. The extended tabs are separated by opposed slots that are configured to receive the spinal fixation rod and for guiding the spinal rod down to the U-shaped channel of the yoke. In some instances, the proximal ends of the extended tabs are not coupled, thereby allowing top entry of the spinal rod into the slots in a direction transverse to its longitudinal axis. While this open configuration is conducive to the placement of the spinal rod, the free unattached proximal ends of the extended tabs may undesirably move during surgery reducing the efficiency of the procedure. To provide additional strength and stability to the extended tabs during use, the proximal ends may be coupled by one or more bridges. Since the bridges at the proximal end close off a top entry of the rod into the slots the spinal rod has to be introduced into the slots between the extended tabs along the longitudinal axis of the rod. While extended tabs coupled with a bridge provide beneficial strength and stability, in order to break the extended tabs off the yoke at the frangible portions at the distal ends, the bridge needs to be severed, so that the respective extended tabs may be individually removed from the yoke. Accordingly, there is a need for an instrument that can desirably cut or fracture one or more bridges that couple extended tabs, as well as to facilitate and/or participate in the breaking of extended tabs from the yoke of the bone anchor. SUMMARY OF THE INVENTION It is an object of the subject invention to provide an improved instrument for cutting a pair of bridges that connect opposing extended tabs extending from a yoke receiver of a spinal bone anchor. It is another object of the invention to provide an improved method of cutting a pair of bridges connecting a pair of opposing extended tabs extending from a yoke receiver of a spinal bone anchor, the bridges being disposed at a proximal end of the extended tabs, and for breaking off the extended tabs from the spinal bone anchor that are connected to the yoke receiver by frangible connectors at a distal end of the extended tabs. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a perspective view of an instrument positioned for cutting bridges connecting a pair of opposing extended tabs extending from a modular yoke attachable to a bone anchor. FIG. 2 is an enlarged view of the encircled portion A of FIG. 1. FIG. 3 is an unexploded perspective view of components of the cutting instrument of FIG. 1. FIG. 4 is an elevation view of the cutting instrument of FIG.