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EP-4534036-B1 - MULTI-FEATURE POLYAXIAL SCREW

EP4534036B1EP 4534036 B1EP4534036 B1EP 4534036B1EP-4534036-B1

Inventors

  • MICKIEWICZ, CHRISTOPHER
  • Wasserbauer, Ellen
  • MANSON, ALEC
  • BIESTER, ERIC
  • MAGUIRE, PAUL S.

Dates

Publication Date
20260513
Application Date
20220302

Claims (15)

  1. A bone anchor assembly (2000), comprising: a bone anchor (2004) having a proximal portion (2204) and a distal threaded bone-engaging portion (2007, 2024); a locking sphere (2006) configured to couple to the proximal portion (2204) of the bone anchor (2004); a receiver member (2002) having a proximal end (2009) defined by a pair of spaced apart arms (2013, 2015) forming a U-shaped recess (2019) therebetween, and a distal end (2011) having a polyaxial seat (2602) formed therein for polyaxially seating the locking sphere (2006); a drag ring (2010) disposed within the receiver member (2002) and configured to exert a friction force on the locking sphere (2006); and a compression member (2008) disposed within the receiver member (2002); wherein a distal facing surface (2022) of the receiver member (2002) is obliquely angled relative to a central proximal-distal axis (A1) of the receiver member (2002) to provide a greater degree of angulation of the bone anchor (2004) relative to the receiver member (2002) in a first direction relative to a second, opposite direction.
  2. The assembly (2000) of claim 1, wherein the receiver member (2002) includes a groove (2012) formed in an outer surface of each of the spaced apart arms (2013, 2015) at a proximal end (2009) thereof; wherein the receiver member (2002) includes: a first recess (2014) formed in the outer surface of each arm (2013, 2015) with at least a portion of the first recess (2014) intersecting the groove (2012), and optionally wherein at least a portion of the first recess (2014) in each arm extends proximally beyond the groove (2012); and a second recess (2016) formed in an outer surface of the receiver member (2002) at a position distal to the first recesses (2014) and optionally longitudinally aligned with one of the first recesses (2014); wherein the first and second recesses (2014, 2016) are configured to couple to a surgical instrument.
  3. The assembly (2000) of claim 2, wherein the first recesses (2014) and/or the second recess (2016) are/is configured to pivotably couple to a surgical instrument.
  4. The assembly (2000) of any preceding claim, wherein the U-shaped recess (2019) is configured to receive a spinal fixation element of various sizes.
  5. The assembly (2000) of any preceding claim, wherein each spaced apart arm (2013, 2015) has a laterally-facing recessed portion (2018) formed on opposite lateral edges of the arm (2013, 2015), each of the lateral-facing recessed portions (2018) facing away from the central proximal-distal axis (A1) of the receiver member (2002), wherein the lateral-facing recessed portions (2018) are configured to engage with a surgical instrument such that the U-shaped recess (2019) remains unobstructed, wherein each of the lateral-facing recessed portions (2018) optionally extend distally from the proximal end (2009) of the spaced apart arms (2013, 2015); and/or wherein each lateral-facing recessed portion (2018) optionally has a concave distal surface (2030) and optionally also a first planar surface (2031), a second planar surface substantially perpendicular to the first planar surface (2031), and a curved surface therebetween.
  6. The assembly (2000) of any preceding claim, wherein the proximal ends (2009) of the spaced apart arms (2013, 2015) lie along a common circular circumferential path; and/or opposing laterally-facing sides (3204, 3306) of the receiver member (2002) taper inward towards the proximal end (2009) of the receiver member (2002).
  7. The assembly (2000) of any preceding claim, wherein a first pair of opposed sides (3304, 3306) of the receiver member (2002) has a first taper with respect to a first plane that contains a proximal-distal axis (A1) of the receiver member; and optionally a second pair of opposed sides of the receiver member (2002) has a second taper with respect to a second plane that contains the proximal-distal axis (A1) and is offset from the first plane and is optionally perpendicular to the first plane.
  8. The assembly (2000) of any preceding claim, wherein a proximal portion of the compression member (2008) includes opposing planar surfaces (4204, 4206) that are angularly offset from one another forming a seat (4210) for receiving a spinal fixation element.
  9. The assembly (2000) of claim 2, wherein material displaced in the formation of the second recess (2016) is configured to restrict movement of the compression member (2008) relative to the receiver member (2002), optionally by the displaced material being received within a corresponding recess (4202) formed in the compression member (2008).
  10. The assembly (2000) of any preceding claim, further comprising one or more of: a pair of reduction tabs (5604) extending proximally from the pair of spaced apart arms (2013, 2015); and/or a fixation element with external square threads configured to be received between the spaced apart arms (2013, 2015) of the receiver member (2002).
  11. The assembly (2000) of any preceding claim, wherein the bone anchor (2004) includes a bore (3404) extending proximally from a distal tip (3410) of the bone engaging portion (2007), wherein the bore (3404) either extends through an entire length of the bone anchor (2004) or is a blind bore (3404); wherein where the bore (3404) extends through an entire length of the bone anchor (2004), the bone anchor (2004) optionally includes at least one outlet (5504) formed in a lateral surface thereof that intersects with the bore (3404).
  12. The assembly (2000) of any preceding claim, wherein the distal bone-engaging portion (2007) further comprises external threads (2024) that extend distally along the bone-engaging portion (2007) to a distal tip (3410) thereof.
  13. The assembly (2000) of any preceding claim, wherein the compression member (2008) is configured to exert a force on the locking sphere (2006) upon distal advancement of the compression member (2008) relative to the receiver member (2002).
  14. The assembly (4600) of any preceding claim, wherein the bone anchor (4602) includes threads of a first pitch formed along a first bone-engaging portion (4604) thereof and threads of a second pitch formed along a second bone-engaging portion (4606) that is proximal of the first bone engaging portion (4604), wherein the first pitch is optionally greater than the second pitch.
  15. The assembly (5000) of any preceding claim, wherein the bone anchor (5002) includes threads formed on a first, distal portion (5004) thereof and a second portion (5006) without threads that is disposed between the first portion (5004) and the proximal portion (5007) of the bone anchor (5002); wherein a length of the second portion (5006) without threads is at least about 30% of a length of the first portion (5004) having threads formed thereon, optionally between about 30% and about 90% of the length of the first portion (5004) having threads formed thereon.

Description

FIELD This disclosure relates generally to improved polyaxial bone anchor assemblies, which can include a plurality of features, e.g., for optimized or improved engagement with surgical instruments, surgical instrumentation, and/or bone, applicable for use in at least thoracolumbar spinal applications. BACKGROUND Bone anchor assemblies can be used in orthopedic surgery to fix bone during healing, fusion, or other processes. In spinal surgery, for example, bone anchor assemblies can be used to secure a rod or other spinal fixation element to one or more vertebrae to rigidly or dynamically stabilize the spine. Bone anchor assemblies typically include a bone screw with a threaded shank that is adapted to be threaded into a vertebra, and a rod-receiving element, usually in the form of a U-shaped slot formed in the head. The shank and rod-receiving assembly can be provided as a monoaxial screw, whereby the rod-receiving element is fixed with respect to the shank, or a polyaxial screw, whereby the rod-receiving element has free angular movement with respect to the shank. In use, the shank portion of each screw is threaded into a vertebra, and once properly positioned, a fixation rod is seated into the rod-receiving element of each screw. The rod is then locked in place by tightening a set-screw, plug, or similar type of fastening mechanism into the rod-receiving element. With prior bone anchor assemblies, there are a large variety of anchors suited for specific uses and this can make it difficult for a user to select the proper anchor, and for suppliers to manufacture and maintain inventories. Further, with prior anchors there are many ways in which use can be challenging, such as when implanting an anchor, when coupling instrumentation to an anchor, when reducing a spinal fixation element toward an anchor, etc. US 2014/277189 A1 discloses a multi-component bone anchor assemblies having larger diameter shanks intended for bottom loading, which include inner and outer ring features to couple the bone anchor to a receiving member. Accordingly, there is a need for improved bone anchor assemblies, particularly assemblies that can be used across a wide variety of situations and provide solutions to various usability challenges. SUMMARY The present invention is defined in claim 1 while preferred embodiments are set forth in the dependent claims. Associated methods are also described herein to aid understanding the invention. The bone anchor assemblies disclosed herein, and methods (not claimed) related to the same, provide for a single bone anchor assembly that can be utilized across a range of spinal surgical procedures, reduce manufacturing burden and cost, and provide for greater flexibility during a surgical procedure. The bone anchor assemblies disclosed herein include an implantable shank and a receiver member having two spaced apart arms which form a U-shaped seat to receive a rod, among other components. The bone anchor assemblies disclosed herein also provide a number of features to enhance capability and usability. These include, for example, features to facilitate better implantation of the shank, better coupling of instrumentation to the anchor, better performance in reducing a spinal fixation element, such as a rod, into the receiver member seat, and others. In one aspect (not claimed), a bone anchor assembly is disclosed that includes a bone anchor having a proximal head portion and a distal threaded bone-engaging portion. The bone anchor further includes a receiver member having a proximal end defined by a pair of spaced apart arms forming a U-shaped recess therebetween, a distal end having a polyaxial seat formed therein for polyaxially seating the head portion of the bone anchor, a groove formed in an outer surface of each of the spaced apart arms at a proximal end thereof, a first recess formed in the outer surface of each arm with at least a portion of the first recess intersecting the groove, and a second recess formed in an outer surface of the receiver member at a position distal to the first recesses. Moreover, the first recesses and the second recesses are configured to couple to a surgical instrument. In some examples, at least a portion of the first recess in each arm can extend proximally beyond the groove. In certain examples, each of the second recesses can be longitudinally aligned with one of the first recesses. In some examples, the first recesses can be configured to pivotably couple to a surgical instrument. In certain examples, the pair of second recesses can be configured to pivotably couple to a surgical instrument. In some examples, the U-shaped recess can be configured to receive a spinal fixation element of various sizes. In certain examples, each spaced apart arm can have a laterally-facing recessed portion formed on opposite lateral edges of the arm, each of the lateral-facing recessed portions facing away from a central proximal-distal axis of the receiver member, wherein the