Patent Publication Number: US-2023157735-A1

Title: Extended tab reinforcement sleeve

Description:
CLAIM OF PRIORITY 
     This application is a continuation of U.S. patent application Ser. No. 16/693,733, filed Nov. 25, 2019, which claims the benefit of U.S. Provisional Patent Application Ser. No. 62/779,905, filed on Dec. 14, 2018, the benefit of priority of which is claimed hereby, and each of which is incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     Orthopedic devices such as rods, plates, tethers, staples, and other devices can be used in various spinal procedures to correct abnormalities (e.g., scoliosis) or to address injuries (e.g., vertebral fracture). In some spinal procedures, anchors and rods can be secured along a spinal column between one or more vertebrae to stabilize a region of the spine. Some surgical procedures performed on the spinal column using such devices have become less invasive. However, some special parts used in minimally-invasive spinal procedures can increase the difficulty of the installation procedure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document. 
         FIG.  1 A  illustrates an isometric view of a housing portion of an anchor and a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  1 B  illustrates an isometric view of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  2 A  illustrates a front view of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  2 B  illustrates a front cross-sectional view of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  2 C  illustrates a front cross-sectional view of a housing portion of an anchor and a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  3 A  illustrates a front view of a sleeve assembly with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure. 
         FIG.  3 B  illustrates a front view of a sleeve assembly with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure. 
         FIG.  4 A  illustrates a side view of a portion of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  4 B  illustrates a front view of a portion of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  4 C  illustrates an isometric view of a cap of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  5    illustrates an isometric view of a portion of an anchor with extended tabs, in accordance with at least one example of this disclosure. 
         FIG.  6 A  illustrates an isometric view of a spring hook of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  6 B  illustrates a side view of a spring hook of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  6 C  illustrates a front view of a spring hook of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  7 A  illustrates an isometric view of a slide lock of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  7 B  illustrates a front view of a slide lock of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  7 C  illustrates a side view of a slide lock of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  7 D  illustrates a front view of a portion of a slide lock of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  8 A  illustrates an isometric view of a cross-section of a housing portion of an anchor and a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  8 B  illustrates a top view of a cross-section of a portion of an anchor and sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  9    illustrates a front view of a sleeve assembly with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure. 
         FIG.  10    illustrates a side view of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  11 A  illustrates a side view of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  11 B  illustrates a side view of a portion of a sleeve assembly with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure. 
         FIG.  11 C  illustrates a side view of a portion of a sleeve assembly with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure. 
         FIG.  12    illustrates a side view of a portion of a sleeve assembly with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure. 
         FIG.  13    illustrates an isometric view of a portion of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  14    illustrates a front view of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  15 A  illustrates a top view of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  15 B  illustrates a side view of a portion of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  16    illustrates a cross-section view of a portion of an anchor and sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  17    illustrates a cross-section view of a sleeve assembly, in accordance with at least one example of this disclosure. 
         FIG.  18    illustrates a front view of a portion of an anchor and sleeve assembly, in accordance with at least one example of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Bone anchors can be used together with connecting members (such as rigid and semi-rigid rods) to straighten a region of a human spine to address an abnormality (e.g., scoliosis), to stabilize a spine following an injury (e.g., fractured vertebrae), or to address degeneration of the spine caused by disease. In minimally invasive spinal procedures to address these issues, multiple small incisions can be made to form multiple small cavities near individual vertebrae. A large amount of the procedure is performed through manipulation of instruments and components extending through the small surgical cavities using special instruments that are able to be manipulated from outside of the cavities. For example, anchors are commonly driven into vertebrae, where the anchors can include extended tabs rigidly coupled to the anchors and having a length sufficient to extend outside of the cavity so that the anchors (and components engaging the anchors) can be manipulated from outside of the cavities. Because the extended tabs comprise a length sufficient to extend through the cavities, they must be separable from the heads of the anchors when the heads remain secured to vertebrae. 
     Some designs include two extensions each coupled to the head of the anchor at a breakaway portion, where each extended tab can be individually bent to allow separation of the extension from the head at the breakaway portions. This design requires relative movement of the extended tabs for separation. However, in some procedures, forces must be transferred from a portion of the extended tabs external to the cavity to a portion of the extended tabs in the cavity and ultimately to the head and/or shank of the anchor. However, many extended tab pedicle screws suffer from instability at the proximal end of the tabs, which can cause unwanted separation at the distal end of the tabs from the housing and can limit a surgeon&#39;s ability to manipulate the extensions. 
     This disclosure addresses the problem of allowing individual separation of the extended tab while allowing transfer of forces and torques through the tabs without unintended separation of the extension tabs from the head by providing a sleeve couplable to the anchor where the sleeve can transfer forces directly to and from the head of the anchor instead of to and from the extended tabs. In one example, the sleeve can include a translating lock coupled to the body of the sleeve and an actuator. An actuator can be operated to translate the lock to engage and secure the anchor to the sleeve at a point below the break-off point of the extensions. This can help to transmit forces between the sleeve and the head of the anchor (and the shank in some examples) while helping to prevent unwanted separation of the extended tabs from the head of the anchor. 
     This overview is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application. 
       FIG.  1 A  illustrates an isometric view of an anchor  102  and sleeve assembly  100 , in accordance with at least one example of this disclosure.  FIG.  1 B  illustrates an isometric view of a sleeve assembly  100 , in accordance with at least one example of this disclosure.  FIGS.  1 A and  1 B  are discussed concurrently below. 
     The sleeve assembly  100  can include a body  104 , a lock  106 , and an actuator (or knob)  108 . The anchor  102  (visible only in  FIG.  1 A ) can include a head  110 , extended tabs  112 A and  112 B ( 112 A is opposite  112 B, but not visible), a breakaway portion  113  (shown in  FIG.  2 C ), a threaded portion  114 , a central bore  116 , and anchor slots  118 A and  118 B (only slot  118 B is visible in  FIGS.  1 A and  1 B ). The body  104  can include a first arm  120 A, a second arm  120 B (referred to collectively as arms  120 ), a central bore  122 , and sleeve slots  124 A and  124 B. The sleeve assembly  100  can further include spring hooks  126 A and  126 B. Also shown in  FIGS.  1 A and  1 B  is axis A, indicators  8 - 8 , and orientation indicators Proximal and Distal. 
     The components of the anchor  102  can be comprised of rigid and semirigid materials such as metals, plastics, composites, or the like. In some examples, the anchor  102  can be comprised of bio-compatible materials, such as stainless steel, titanium, or the like. In some examples, the anchor  102  can be comprised of only one material, and can be comprised of multiple materials in other examples. 
     The head  110  of the anchor  102  can be coupled to a shank, as shown in  FIG.  5   , at a distal portion of the head  110  with the shank extending distally therefrom and where the axis A can be a central axis for the head  110  and the shank. In other examples, the shank can deviate from the axis A at various angles. The shank can be a threaded shank or screw including male threads configured to engage bone, such as a relatively coarse thread pattern. In some examples, the shank can be configured to threadably secure to a vertebra of a spine of a human, as shown and discussed in  FIG.  5    below. The shank can be an integral component to the head  110  in some examples, coupled to a distal portion of the head  110 . In other examples, the shank can be a portion of a fastener that is a separate component from the head  110  and can be disposed within a bore of the head  110  and configured to be retained therein. 
     The anchor slots  118 A and  118 B of the anchor  102  can be generally U-shaped, in some examples, and can be configured to receive a connecting member (such as a connecting rod or wire) therethrough. In some examples, the head  110  can have flat sides and one or more tool interfaces, as discussed further below. The breakaway portions  113 A and  113 B can be a portion of the anchor  102  coupling the head  110  to the extended tabs  112 A and  112 B, respectively, where the breakaway portions  113  can have a thickness that is smaller than a thickness of the head  110  or the extended tabs  112 A and  112 B (only tab  112 B is visible in  FIGS.  1 A and  1 B ) that surrounds the breakaway portions  113 A and  113 B. The reduced thickness of the breakaway portions  113 A and  113 B can facilitate separation and removal of the extended tabs  112 A and  112 B from the head  110 . 
     The threaded portion  114  can be a female threaded portion within the anchor slots  118 A and  118 B of the head  110  and the extended tabs  112 A and  112 B. In some examples, the threaded portion  114  can be relatively fine threading (such as machine-type threading) configured to receive a component having male threading, such as a closure top or set screw configured to retain a connecting member or rod. The threaded portion  114  can include any known thread forms commonly utilized for pedicle screws. 
     The extended tabs  112 A and  112 B can extend substantially proximally from the head  110  and substantially parallel to axis A. Together, the extended tabs  112 A and  112 B can form an incomplete hollow cylinder separated by anchor slots  118 A and  118 B. The anchor slots  118 A and  118 B can be slots between the extended tabs  112 A and  112 B. The extended tabs  112 A and  112 B can be coupled to the head  110  by the break off portions  113 A and  113 B, as noted above. 
     Sleeve assembly  100  can be a generally hollow cylindrical member including the elongate body  104 . The components of the sleeve assembly  100  can be comprised of rigid and semi-rigid materials such as metals, plastics, composites, or the like. In some examples, the sleeve assembly  100  can be comprised of biocompatible materials, such as stainless steel, titanium, cobalt chromium, or the like. In some examples, the sleeve assembly  100  can be comprised of only one material, and can be comprised of multiple materials in other examples. 
     The central bore  122  of the body  104  can be sized and shaped to receive the anchor  102  therein. The arms  120  can extend distally from the actuator  108  and can be separated by sleeve slots  124 A and  124 B, which can be sized to respectively align with the anchor slots  118 A and  118 B of the anchor  102 . Each of the first arm  120 A and the second arm  120 B can have a length sized to extend over the extended tabs  112 A and  112 B of the anchor  102 , while exposing part of the head  110 . In some examples, first arm  120 A and the second arm  120 B can have a length sized to extend over the entirety of the head  110 . 
     The lock  106  can be an elongate member secured to the body  104  and can be movable relative thereto. The lock  106  can be engaged with the actuator (or knob)  108  at a proximal portion of the lock  106 , where the actuator  108  can also be secured to the body  104 , but movable relative thereto. A distal portion of the lock  106  can be engageable with the spring hooks  126 A and  126 B, which can be biased or spring member comprised of resilient materials, such as spring steel, or the like. The spring hooks  126  can be secured to a distal portion of the body  104  and can be engaged by the lock  106  to be moved radially inward from the body  104  to engage the head  110  of the anchor  102  to secure the head  110  to the sleeve. 
     In operation of some examples, the extended tabs  112 A and  112 B can be inserted into the central bore  122  of the arms  120  with a proximal portion of the head  110  of the anchor  102  until the sleeve engages with the head  110  distally. The anchor  102  can be inserted into sleeve arms  120  either before or after the anchor  102  is inserted into a cavity and before or after the anchor  102  is secured to a bone. 
     Once the anchor  102  is fully inserted into the central bore  122 , the knob  108  can be operated (for example, by rotating the knob) to move the lock  106  to engage and move the spring hooks such that inwardly extending projections of the spring hooks  126  are moved radially inward. The knob  108  can be rotated until the spring hooks  126  extend radially inward to fully engage a rim or channel of the head  110  to secure the anchor  110  to the body  104 . By utilizing a lock with deflecting hooks, the sleeve assembly  100  provides a locking mechanism without small components (such as coil springs or pins) and with a relatively low number of parts. 
     In further operation of some examples, once a patient&#39;s spinal region (and specifically a vertebra) is prepared, the anchor  102  can be extended into an incision and aligned with a portion of the vertebra (for example a guide bore) configured to receive a shank. Once the shank is engaged with the guide bore in the vertebra, a torque can be applied to the head  110  about axis A using a tool to drive the shank into the vertebra. Once the shank is secured into the vertebra, a connecting member can be passed through the anchor slots  118 A and  118 B of the extended tabs  112 A and  112 B and can be reduced down through the sleeve slots  124 A and  124 B and into the head  110 . At a later time, or during reduction, a closure top (or other fastener) can be inserted into central bore  122  of the body  104  and can be threaded into the threaded portion  114  of the anchor  102  and down to the head  110  to retain the connecting member in the head  110  of the anchor  102 . 
     In some examples, the closure top or fastener (e.g., set screw) can be used to secure or reduce a connecting member into the head  110 , with the sleeve  100  helping to prevent premature breakage at  113  during this reduction. The sleeve  100  can also be used to reinforce the extended tabs  112  to prevent unwanted break off when other external forces and torques are applied to the extended tabs  122 . In one example, the sleeve  100  can reinforce the tabs  112  during hand positioning or manipulation of the anchor  100 , such as when rotating an anchor already secured to a vertebral body. This type of hand positioning and rotation of the sleeve  100  and the anchor  102  can be common during a spinal de-rotation procedure, for example. 
       FIG.  2 A  illustrates a front view of the sleeve assembly  100 , in accordance with at least one example of this disclosure.  FIG.  2 B  illustrates a front cross-sectional view across section  2 B- 2 B of the sleeve assembly  100 , in accordance with at least one example of this disclosure.  FIG.  2 C  illustrates a focused portion  2 C front cross-sectional view of the anchor  102  and the sleeve assembly  100 , in accordance with at least one example of this disclosure.  FIGS.  2 A- 2 C  are discussed concurrently below. 
     The sleeve assembly  100  can include the body  104 , the lock  106 , and the actuator  108 . The anchor  102  (visible only in  FIG.  2 C ) can include the head  110 , the extended tabs  112 A and  112 B, the breakaway portion  113 , the threaded portion  114 , the central bore  116 , and the anchor slots  118 A and  118 B. The body  104  can include the first arm  120 A (including a first arm channel  121 A), the second arm  120 B (including a second arm channel  121 B), the central bore  122 , the sleeve slots  124 A and  12413 , and pockets  128 A and  128 B (collectively referred to as pockets  128 ). The head  110  can include channels  111 A and  111 B (only  111 A shown in  FIG.  2 C ), which can each include a channel flat  115 . The sleeve assembly  100  can further include the spring hooks  126 A and  126 B, which can include barbs  130 A and  130 B, respectively, each of which can include a barb flat  131 . The lock  106  can include a first lock arm  129 A and a second lock arm  129 B, each of which can include a distal tapered portion  133 . Also shown in  FIG.  2 A  are axis A, section indicators  2 B, and orientation indicators Proximal and Distal. Also shown in  FIG.  2 B  are axis A, section indicator  2 C, and orientation indicators Proximal and Distal. Also shown in  FIG.  2 C  are orientation indicators Proximal and Distal 
     The sleeve assembly  100  and the anchor  102  can be similar to the sleeve assembly  100  and the anchor assembly  102  of  FIGS.  1 A and  1 B ; however,  FIGS.  2 A- 2 C  show additional details of the sleeve assembly  100  and the anchor  102 . For example,  FIG.  2 B  shows pockets  128 A and  128 B of arms  120 A and  120 B, respectively, where each of the pockets  128  is located at a distal portion of each of the arms  120  and each pocket  128  is connected to one of the arm channels  121 . For example, the first pocket  128 A is connected to a distal portion of the first arm channel  121 A and the second pocket is connected to a distal portion of the second arm channel  121 B. 
     Each pocket  128  can be a cavity open to the central bore  122  of the body  104  and can extend radially outward therefrom. Each pocket  128  can be sized to receive one lock arm  129  and one spring hook  126  therein. In some examples, each pocket  128  can be sized such that when the lock arm  129  and spring hook  126  are disposed within the pocket and when the barb  130  is engaged with the channel  111 , there is relatively little space between a radially outer wall of the pocket, the lock arm  129 , the spring hook  126 , and the head  110  of the anchor. The tolerance stackup between the pocket  128  and the lock arm  129 , spring hook  126 , and barb  130  can range from a clearance fit to an interference fit, depending upon how tightly the sleeve assembly  100  needs to be connected to the anchor  110 . This can help to limit radially outward movement of the spring hook  126  when the lock arm  129  is in a locked position, helping to prevent the spring hook  126 , and therefore the sleeve assembly  100 , from disengaging the head  110 . The low gap between these components can also help to transfer forces and stress between the head  110  and the sleeve assembly  100 , which can further help limit bending of the anchor  102  and the sleeve assembly. Further, the arm  129  can act as a wedge within the pocket  128  to drive the spring hook into position by engaging the pocket  128  and a radially outer portion of the spring hook  126 . 
       FIG.  2 C  also shows the channel  111 A of the head  110 , which can be sized and shaped to receive the barb  130 A when the lock arm  129 A is in a locked position. When in the locked position, the barb flat  131  can engage the channel flat  115  to help limit proximal translation of the sleeve assembly  100  relative to the head  110 . The barb flat  131  can extend substantially around a perimeter of the head  110 , in some examples, and can be flat or planar from a proximal perspective. Similarly, the barb flat  131  can be flat or planar from a proximal perspective. In other examples, the barbs  130  can be of other shapes, such as a hook, to further help limit relative movement of the sleeve assembly  100  relative to the head  110  of the anchor  102 . A distal surface  165  connecting the barb to the distal tip  164  can be rounded to help improve disengagement of the barb  131  from the head  110 . In other examples, the distal surface  165  can be flat. 
       FIGS.  2 B and  2 C  also show the distal tapered portion  133  of each lock arm  129 . As shown in  FIG.  2 B , the distal tapered portion  133  can rest at a proximal portion of the pocket  128  when the lock  106  is in an unlocked position (for example, when the lock arm  129 A is translated proximally). 
     In operation of some examples, the lock  106  can be in the unlocked position, as shown in  FIG.  2 B , where the lock  106  is translated proximally sufficiently to allow the spring hooks  126  to be locked within the pockets  128 . That is, each spring hook  126  does not extend into the central bore  122  when the lock  106  is in the unlocked position. When it is desired to secure the sleeve assembly  100  to the anchor  102 , the head  110  of the anchor  102  can be inserted into the central bore  122  of the sleeve assembly, as described above with respect to  FIGS.  1 A and  1 B . When the anchor  102  is completely inserted into the central bore  122 , the channels  131  of the anchor can align with the pockets  128 . At this point, the actuator  108  (or knob) can be rotated to cause distal translation of the lock  106 . Distal translation of the lock  106  causes distal translation of the lock arms  129  within their respective lock slots  121 A. 
     Because the distal portion  133  of each lock arm  129  is tapered and rests at a proximal opening of each pocket in the unlocked position of the lock  106 , the lock arms  129  thereby retain their position within the pocket  128  while allowing the spring hooks  126  to be disengaged from the head  110  and to be located within the pocket  128  when the lock arms  129  are in the unlocked (proximal) positions. 
     As the lock arms  129  extend into the pockets  128  (as shown in  FIG.  2 C ), an outer wall  135  of the pockets  128  guide the lock arms  129  to deflect radially inward to contact the spring hooks  126 , which causes the spring hooks  126  to move radially inward. Because each outer wall  135  is angled, the spring hooks  126  are deflected further radially inward as the lock arms  129  are translated further distally into the pockets  128 , causing the barbs  130  of the spring hooks to extend radially inward from the pockets  128  into the central bore  122  to engage the channels  111  of the head  110  of the anchor. The radially inward extension of the spring hooks  126  can be limited by contact between the barb  130  and the channel  111  and/or the spring hooks  126  and the head  110 , and/or by contact between a distal portion of the pockets  128  and a distal end of the tapered portion  133  of the lock arms  129 . 
     When the lock  106  is in the locked position, proximal translation of the head  110  relative to the sleeve assembly  100  is limited by contact between the extended tabs  112  and the body  104 , distal translation of the head  110  relative to the sleeve assembly  100  is limited by engagement of the barbs  130  with the channel  111 , and movement transverse to the axis A of the head  110  relative to the sleeve assembly  100  is limited by contact between the anchor  102  and the body  104 , thus securing the anchor  102  to the sleeve assembly  100  when the lock  106  is in the locked position. Because the channels  111  are positioned distally of the breakaway portions  113  of the extended tabs  112 , interaction between the sleeve assembly  100  and the head  110  (that is, interaction between the spring hooks  126  and the head  110 ) is less likely to cause unwanted separation of the extended tabs  112  from the head  110  during manipulation of the sleeve assembly  100  during a procedure. 
     When it is desired to disengage the sleeve assembly  100  from the anchor  102 , the actuator  108  can be operated to translate the lock  106  proximally, causing the lock arms  129  to move proximally, such that the arms  129  will move out of the pockets  128  enough to allow the spring hooks  126  to retract into the pockets  128  while disengaging from the channel  111  of the head  110 . In some examples, the spring hooks  126  can be biased to a retracted position, as shown in  FIG.  2 B , so that when the force applied by the lock arms  129  is removed, the spring hooks  126  retract into the pockets  128  without the application of a force external to the spring hooks  126 . 
     When the barbs disengage from the channel  111  of the head  110 , the anchor  102  can be translated distally relative to the sleeve assembly  100 , allowing the anchor  102  to be removed, if desired. Because the pockets  128  (together with the anchor  102 ) substantially surround the spring hooks  126 , the pockets  128  help to protect the spring hooks  126  from interference from tissue of a patient, where such interference can prevent the sleeve assembly  100  disengaging from the anchor  102 . The pockets  128  therefore help to ensure the sleeve assembly  100  can be removed from the anchor  102 , as desired. 
       FIG.  3 A  illustrates a front view of the sleeve assembly  100  with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure.  FIG.  3 B  illustrates a front view of the sleeve assembly  100  with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure.  FIGS.  3 A and  3 B  are discussed below concurrently. 
     The sleeve assembly  100  of  FIGS.  3 A and  3 B  can be consistent with the sleeve assembly of  FIGS.  1 A- 2 C , but  FIGS.  3 A and  3 B  can show additional details of the sleeve assembly. For example,  FIGS.  3 A and  3 B  show how the actuator  108 , body  104 , and lock  106  are connected and how they interact. 
       FIGS.  3 A and  3 B  show pin  132 , which can be a rigid or semi-rigid elongate fastener, such as a cylindrical pin, rivet, screw, or the like. The pin  132  can pass through a pin bore  146  of the lock  106  and can also pass through a pin channel  148  of the body  104  to couple the lock  106  to the body  104 . The pin channel  148  can have an axial length longer than a diameter of the pin  132  to allow the pin to move in a direction substantially parallel to axis A. This movement can permit the lock  106  to move axially relative to the body  104 . The pin channel  148  can also be sized to have a width similar to the diameter of the pin  132  to help limit non-axial movement of the lock  106  with respect to the body  104 . 
       FIGS.  3 A and  3 B  also show that lock  106  can include a proximal bore  136  and an undercut  138 , which can be sized and shaped to receive tabs  140 A- 140 N (collectively referred to as tabs  140 ) and projections  142 A- 142 N (collectively referred to as projections  142 ), respectively. The undercut  138  can be spaced away from a proximal end of the lock  106  such that once the projections  142  are disposed within the undercut  138 , axial movement of the actuator  108  is limited proximally and distally with respect to the lock  106 . 
       FIGS.  3 A and  3 B  also show that actuator  108  includes internal threading  150 , which can be complementary to external threading  144  of a proximal portion  143  of the body  104 . Interaction (screwing and unscrewing, for example) of internal threading  150  of the actuator can engage the external threading  144  of the proximal portion of the body  143  to cause movement of the actuator  108  relative to the body  104 . 
     For example, during operation of the sleeve assembly  100 , a torque T1 about axis A can be applied to the actuator  108  to screw the internal threading  150  of the actuator  108  onto the internal threading  144  of the proximal portion  143  of the body  104 . Because the actuator  108  is coupled to the lock  106  via tabs  140 , as the actuator  108  screws further (distally) onto the body  104 , the lock  106  (and the lock arms  129 ) are translated distally with respect to the body, allowing the lock arms  129  to engage the spring hooks  126 , as discussed above. When it is desired to unlock the spring hooks  126  from the anchor  102 , the actuator  108  can be rotated in a direction opposite the torque T1 to translate the actuator  108  and the lock  106  proximally with respect to the body  104 . By providing a threaded interface to operate the actuator  108  to control translation of the lock  106 , the relatively small translation of the lock  106  with respect to the body is given a relatively high degree of controllability to the user while also providing user feedback during tightening and loosening. 
       FIGS.  3 A and  3 B  also show tool interfaces  134 A and  134 B, which can be bores in the lock  106  and/or the body  104 , where the tool interfaces can support another tool, such as a reducer, counter-torque, or de-rotator, for example. 
       FIG.  4 A  illustrates a side view of a portion of the body  104  of the sleeve assembly  100 , in accordance with at least one example of this disclosure.  FIG.  4 B  illustrates a front view of a portion of the body  104  of the sleeve assembly  100 , in accordance with at least one example of this disclosure.  FIG.  4 C  illustrates an isometric view of the knob  108  of the sleeve assembly  102 , in accordance with at least one example of this disclosure.  FIGS.  4 A- 4 C  are discussed below concurrently. 
     The sleeve assembly  100  of  FIGS.  4 A- 4 C  can be consistent with the sleeve assembly of  FIGS.  1 A- 3 B , but  FIGS.  4 A- 4 C  show additional details of the sleeve assembly. For example,  FIGS.  4 A and  4 B  show the proximal portion  143  of the body  104  extending proximally from the body arms  120 A and  120 B, where the male threaded portion  144  extends to a proximal end of the body  104 . The proximal portion  143  can include a pair of proximal arms extending from the body  104 , offset from the body arms  120 . In other examples, the proximal arms of the proximal portion  143  can be aligned with the body arms  120 . 
       FIG.  4 B  also shows the pin channel  148  extending proximally to distally along axis A where the pin channel  148  can terminate proximally before the threaded portion  144 .  FIG.  4 A  further shows tool interface  134 A which can be a slot or bore extending substantially perpendicular to the axis A. 
     Also shown in  FIG.  4 A  is a spring hook channel  152 , which can include a proximal portion  154  and a distal portion  156 . The proximal portion  154  can have a width substantially wider than a width of the distal portion  156  for receiving a head or wings of the spring hook  126 , as discussed further below. Though the spring hook channel  152  is shown as being a substantially T-shaped channel, the spring hook channel  152  can be of other shapes, such as an I-shape, a J-shape, or the like. In some examples, the spring hooks  126  can be secured to the body  104 , such as by laser-welding, within the spring hook channels  152 , such as at the proximal portion  154  to provide a flex of the spring hook  126  relative to the body  104 . 
       FIG.  4 C  shows additional details of the actuator  108  such as a knob portion  158  and the fingers  140  (each including the tabs  142 ). The knob portion  148  can be substantially cylindrical in some examples, and can have other shapes in other examples, such as hexagonal, octagonal, or the like. The fingers  140  can each extend distally from the knob portion  158  and can be in a cantilevered arrangement therewith. 
     Each of the fingers  140  can be circumferentially spaced. For example, finger  140 C can be spaced from finger  140 D by a gap G, which can allow the fingers  140  to deflect radially inward for attachment of the actuator  108  to the locking portion  106 . The number of fingers can be any number, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, or the like. Similarly, the gap G can be varied for a desired number of fingers and for a desired radially inward deflection of the fingers  140 . The projections  142  of the fingers  140  can extend radially outward therefrom at a distal portion (and in some examples at a distal termination) of each of the fingers  140 . 
       FIG.  5    illustrates an isometric view of an anchor  502  with a sleeve assembly  500 , in accordance with at least one example of this disclosure. The anchor  502  can include a shank  509 , a head  510 , and extensions  512 A and  512 B. Also shown in  FIG.  5    are a cutaneous portion  50 , an opening  52 , and vertebrae V1, V2, and V3. 
     The anchor  502  of  FIG.  5    can be consistent with the anchors discussed above. Similarly, the sleeve assembly  500  can be consistent with the sleeve assembly  100  discussed above with respect to  FIGS.  1 - 4 C .  FIG.  5    shows how the sleeve assembly  500  and the anchor  502  can be used in an example operation. In operation of some examples, an incision can be made on a posterior portion of a patient along the patient&#39;s vertebral column, for example, along the patient&#39;s thoracic spine. For example, an incision can be made on the cutaneous portion  50  where the incision extends through the dermis and subcutaneous tissue to create the opening  52  and exposes or partially exposes the vertebrae V1-V3. In some cases, multiple incisions can be made to minimize invasion. Next, a punch may be used to break the cortical bone to create a pilot or guide hole in a vertebra for the anchor  502 . Once the vertebra (for example, the vertebra V1) is prepared, the anchor  502  can be extended into the opening  52  such that the anchor  502  can be engaged with the vertebra V1, for example. The shank  509  of the anchor  502  can then be driven into, for example, a pedicle of the vertebra V1 to secure the anchor  502  to the vertebra V1 while the anchor and the sleeve  502  can extend beyond the opening  52 . 
     While in this position, the extended tabs  512  can receive the sleeve assembly  500  thereon. In other examples, the sleeve assembly  500  can be secured to the anchor  502  prior to securing the anchor  502  to the vertebra V2. Once the sleeve assembly  500  is secured to the anchor  502 , the sleeve assembly  500  can be manipulated by hand (or tool) to position vertebra V1, such as during a de-rotation procedure. During this rotation, the sleeve assembly  500  can help prevent unwanted separation of the extended tabs  512  from the head  510  of the anchor  502 , where the lock of the sleeve assembly  500  can help to prevent such separation. 
       FIG.  6 A  illustrates an isometric view of the spring hook  126 , in accordance with at least one example of this disclosure.  FIG.  6 B  illustrates a side view of the spring hook  126 , in accordance with at least one example of this disclosure.  FIG.  6 C  illustrates a front view of the spring hook  126 , in accordance with at least one example of this disclosure.  FIGS.  6 A- 6 C  are discussed below concurrently. 
     The spring hook  126  can include the barb  130  (including the flat  131 ), a body  160 , tabs  162 A and  162 B (collectively referred to as tabs  162 ), and a distal tip  164 , which can include the barb  130 , and a tapered portion  166 . 
     The spring hook  126  of  FIGS.  6 A- 6 C  can be consistent with the spring hook  126  of  FIGS.  1 - 4 C , except that  FIGS.  6 A- 6 C  show additional details of the spring hook  126 . As discussed above, the spring hook  126  can be comprised of resilient materials, such as steels, titanium alloys, or the like. Each of the components of the spring hook can be comprised of a single material in some examples, and can be an assembly comprised of multiple materials in other examples. 
     The body  160  can be substantially thin and elongate and can be connected to tabs  162  at a proximal portion of the body  160  and the distal tip  164  at a distal portion of the body  160 . The tabs  162  can respectively extend outward from the body (in substantially opposing directions). The tapered portion  166  of the distal tip  164  can be tapered toward the barb  130  as the distal tip  164  extends distally. In some examples, the tapered portion  166  of the distal tip  164  can have a taper that is sized and shaped to substantially match an angle of the outer wall  135  of the pockets  128  of the sleeve body  120  to help reduce engagement and friction between the spring hook and the outer wall  135 . Also, a width W of the distal tip  164  can be wider than the distal portion  156  of the opening of the hook channel  152  to limit radially outward movement of the distal tip  164 . 
       FIG.  7 A  illustrates an isometric view of the lock  106  of the sleeve assembly  102 , in accordance with at least one example of this disclosure.  FIG.  7 B  illustrates a front view of the lock  106  of the sleeve assembly  102 , in accordance with at least one example of this disclosure.  FIG.  7 C  illustrates a side view of the lock  106  of the sleeve assembly  102 , in accordance with at least one example of this disclosure.  FIG.  7 D  illustrates a front view of a portion of the lock  106  of the sleeve assembly  102 , in accordance with at least one example of this disclosure.  FIGS.  7 A- 7 D  are discussed below concurrently. 
     The lock  106  can include a proximal portion  170  and the lock arms  129 A and  129 B. The proximal portion  170  can include the tool interfaces  134 A and  134 B, and the pin bore  146 . The lock arms  129 A and  129 B can include distal portions  172 A and  172 B, respectively. The distal portions  172 A can each include a distal tip  174 , partially formed by cut portion  176 . Also, the lock arm  129 A can include chamfers  178  and  179  and the lock arm  129 B can include chamfers  180  and  181 . The distal tip  174  can include a first portion  182 , a second portion  184 , a third portion  186 , and a fourth portion  188 . Also shown in  FIGS.  7 A- 7 D  are width W, thicknesses t1, t2, t3, and t4, and orientation indicators Proximal and Distal. 
     The distal portions  172  of the lock arms  129  can be of a width W relatively smaller than that of a width of the proximal portion of the lock arms  129  to help allow the distal portions  172  to deflect radially inward for insertion into the pocket  128  of the body  104  during locking and unlocking operations. The distal tip  174  can also be sized and shaped for insertion into the pockets, as discussed further below. Also, the chamfers  178 - 181  can be sized and shaped to be retained by the body (for example, in a dovetail arrangement), as discussed below with respect to  FIGS.  8 A- 8 B . 
     The distal tip  174  can include four portions of varying thicknesses, in some examples. The first portion  182  can have the first thickness t1; the second portion  184  can have the second thickness t2; the third portion  186  can have the third thickness t3, and, the fourth portion  188  can have the fourth thickness t4. In some examples, the thicknesses t1, t2, t3, and t4 can all be different where the fourth thickness t4 is smaller than the third thickness t3, which is smaller than the second thickness t2, which is smaller than the first thickness t1. In other examples, some or all of the thicknesses t1-t4 can be the same thickness. In some examples, each of the first portion  182 , the second portion  184 , the third portion  186 , and the fourth portion  188  can be tapered from a larger to smaller thickness as the distal tip portion  174  extends proximally to distally. Such a tapered profile of the distal tip portion  174  can allow for the spring hook  126  to bias radially outward in an unlocked position within the pocket  128  of the body  104 . That is, the third portion  186  can also have the thickness t3 to allow the third portion  186  to rest within a proximal portion (or proximal entrance) of the pocket  128  when the lock  106  is in an unlocked position to retain the lock  106  while allowing the spring hook  126  to extend radially outward to allow for clearance for the head  110  of the anchor  102  to enter the central bore  122 . 
     Though four portions of the distal tip  174  are shown, the distal tip  174  can have fewer portions (such as 1, 2, or 3 portions) or more portions. Also, the thicknesses and tapers of the portions of the distal tip  174  can vary in other examples. 
       FIG.  8 A  illustrates an isometric cross-sectional view of the anchor  102  and the sleeve assembly  100  across indicators  8 - 8  of  FIG.  1 A , in accordance with at least one example of this disclosure.  FIG.  8 B  illustrates a top view of a cross-section of the anchor  102  and the sleeve assembly  100  across indicators  8 - 8  of  FIG.  1 A , in accordance with at least one example of this disclosure. 
     The anchor  102  and the sleeve assembly  100  can be consistent with the anchor and sleeve assemblies discussed above; however,  FIGS.  8 A and  8 B  show additional details of the anchor  102  and the sleeve assembly  100 . For example,  FIG.  8 B  shows show the extended tabs  112 A and  112 B of the anchor  102  can be secured to the body  104  using chamfered (or dovetailed) portions. 
     Each of the extended tabs  112 A and  112 B can include chamfered portions. The extended tab  112 A can include chamfers  190  and  191  and the extended tab  112 B can include chamfers  192  and  193 . The body  104  can include radially inward extending projections, where each projection has a chamfer complimentary to the chamfers of the extended tabs  112 A and  112 B. The arm  120 A can include inner projections  194 A and  194 B, which can respectively include faces  195 A and  195 B. The arm  120 B can include inner projections  196 A and  196 B, which can respectively include faces  197 A and  197 B. 
     The face  195 A can engage the chamfer  190  and the face  195 B can engage the chamfer  191  in a dovetail-type arrangement to retain the extended tab  112 A in the central bore  122 , by preventing movement of the extended tab  112 A in directions non-parallel to axis A, while still allowing translation of the extended tab  112 A with respect to the body  104  parallel to the axis A. Similarly, the face  197 A can engage the chamfer  192  and the face  197 B can engage the chamfer  193  in a dovetail-type arrangement to retain the extended tab  112 B in the central bore  122 , by preventing movement of the extended tab  112 B in directions non-parallel to axis A, while still allowing translations of the extended tab  112 B with respect to body  104  parallel to the axis A. Generally, this arrangement can allow for insertion of the anchor  102  into the body  104  and can prevent non-axial movement of the anchor  102  with respect to the body. 
       FIGS.  8 A and  8 B  also show how the lock  106  can be secured to the body  104 . The lock arm  129 A can include chamfers  178  and  179  and the lock arm  129 B can include chamfers  178  and  179 . The body  104  can include radially outward extending projections, where each projection has a chamfer complimentary to the chamfers of the lock arms  129 A and  129 B. The arm  120 A can include outer projections  198 A and  198 B, which can respectively include faces  199 A and  199 B. The arm  1208  can include outer projections  200 A and  200 B, which can respectively include faces  201 A and  201 B. 
     The face  199 A can engage the chamfer  179  and the face  199 B can engage the chamfer  178  in a dovetail-type arrangement to retain the lock arm  129 A in the first arm channel  121 A by preventing movement of the lock arm  129 A in directions non-parallel to axis A while still allowing translation of the lock arm  129 A with respect to the body  104  parallel to the axis A. Similarly, the face  201 A can engage the chamfer  181  and the face  201 B can engage the chamfer  180  in a dovetail-type arrangement to retain the lock arm  129 B in the second arm channel  121 B by preventing movement of the lock arm  129 B in directions non-parallel to axis A while still allowing translations of the lock arm  129 B with respect to the body  104  parallel to the axis A. Generally, this arrangement can allow for movement of the lock arms  129 A and  129 B with respect to the body  104  to allow the lock  106  to secure the anchor  102  to the body  104 . 
     Though the extended tabs  112 A and  112 B, the lock  106 , and the body  104  are discussed above as having chamfered portions to create a dovetail arrangement, other geometries and connection methods can be used to secure the extended tabs  112 A and  112 B and the lock  106  to the body  104  while enabling relative translation of the extended tabs  112 A and  112 B and the lock  106  to the body  104 . 
       FIG.  9    illustrates a front view of a sleeve assembly  900  with a portion of the sleeve assembly  900  in phantom, in accordance with at least one example of this disclosure. The sleeve assembly  900  can include a threaded engagement between an actuator and a two-piece lock. Any of the previously discussed sleeve assemblies can be modified to include such an actuator and lock assembly. 
     The sleeve assembly  900  can include a body  904 , a lock  906 , and an actuator  908 . The body  904  can include a pin slot  910 , the actuator  908  can include a pin channel  912  and a male threaded portion  914 , and the lock  906  can include a female threaded portion  916 . Also shown in  FIG.  9    is axis A and orientation indicators Proximal and Distal. 
     The sleeve assembly  900  can be similar to the sleeve assemblies discussed above, except that the actuator  908  can be secured to the body via a pin passing through the pin slot  910  of the body  904  and the channel  912  of the actuator. The sleeve assembly  900  can also differ in that it can include the male threaded portion  914  on the actuator  908 , which can drive the female threaded portion  916  of the lock to translate the lock  906  relative to the body. 
       FIG.  10    illustrates a side view of a sleeve assembly  1000 , in accordance with at least one example of this disclosure. The sleeve assembly  1000  can include a spring boss, and a guide boss to translate a lock. Any of the previously discussed sleeve assemblies can be modified to include such a spring boss and guide boss. 
     The sleeve assembly  1000  can include a body  1004 , a lock  1006 , and an actuator  1008 . The body  1004  can include spring channel  1010 . The lock  1006  can include a guide channel  1012 , and the actuator  1008  can include a spring boss  1014 , and a guide boss  1016 . Also shown in  FIG.  10    is axis A and orientation indicators Proximal and Distal. 
     The sleeve assembly  1000  can be similar to the sleeve assemblies discussed above, except that the actuator  1008  can be secured to the body via the spring boss  1014 , which can be disposed within the spring channel  1010  of the body  1004 . The spring boss  1014  can rotate within the spring channel  1010  and can limit axial translation of the actuator  1008  with respect to the body  1004 . 
     The sleeve assembly  1000  can also differ in that it can include the guide boss  1016 , which can be disposed within the guide channel  1012  of the lock  1006 . In some examples, the guide channel  1012  can be a diagonal channel configured to cause axial translation of the lock  1006  when the actuator  1008  is rotated. 
     In assembly of some examples, the lock  1006  (on both sides) can be aligned with channels of the body  1004 . The guide boss  1016  can be inserted into the guide channel  1012 . Then, the actuator  1008  and the lock  1006  can be translated distally together until the spring bosses extend radially into the spring channel  1010 . 
       FIG.  11 A  illustrates a side view of a sleeve assembly  1100 , in accordance with at least one example of this disclosure.  FIG.  11 B  illustrates a side view of a portion of the sleeve assembly  1100  with a portion of the sleeve assembly  1100  in phantom, in accordance with at least one example of this disclosure.  FIG.  11 C  illustrates a side view of a portion of the sleeve assembly  1100  with a portion of the sleeve assembly  1100  in phantom, in accordance with at least one example of this disclosure. The sleeve assembly  1100  can include a ramp engagement between an actuator and a flexible lock. Any of the previously discussed sleeve assemblies can be modified to include such ramp interface and flexible lock. 
     The sleeve assembly  1100  can include an anchor  1102 , a body  1104 , a lock  1106 , and an actuator  1108 . The body  1104  can include a lock channel  1109 . The lock  1106  can include a proximal ramp  1112  and a distal flexible portion  1114 . The actuator  1108  can include a guide ramp  1116 . The anchor  1102  can include a head  1110  having a notch  1111 . Also shown in  FIG.  11    is axis A and orientation indicators Proximal and Distal. 
     The sleeve assembly  1100  can be similar to the sleeve assemblies discussed above, except that the actuator  1108  can engage the proximal ramp  1112  of the lock  1106  such that when the actuator  1008  is rotated, the guide ramp  1116  of the actuator engages the proximal ramp  1112  to cause the lock  1106  to translate parallel to the axis A. The flexible portion  1114  of the lock  1106  can translate within the lock channel  1109  of the body. When the actuator  1108  is moved to the locked position, the flexible portion  1114  can move into the notch  1111  of the head of the anchor  1102  to retain the anchor  1102  within the sleeve assembly  1100 . 
       FIG.  12    illustrates a side view of a portion of a sleeve assembly  1200  with a portion of the sleeve assembly in phantom, in accordance with at least one example of this disclosure. The sleeve assembly  1200  can include a rotating lock securable to a channel of an anchor. Any of the previously discussed sleeve assemblies can be modified to include such translating lock assembly. 
     The sleeve assembly  1200  can include an anchor  1202 , a body  1204 , a lock  1206 , and an actuator. The body  1204  can include arms  1220 A and  1220 B. The lock  1206  can include a ring portion  1207 . The anchor  1202  can include a head  1210  having a channel  1211 . Also shown in  FIG.  12    is axis A and orientation indicators Proximal and Distal. 
     The sleeve assembly  1200  can be similar to the sleeve assemblies discussed above, except that the lock  1206  can include the ring portion  1207 . The lock  1206  can be rotatable by the actuator to rotate the ring portion  1207  into the channel  1211  of the head  1210  to secure the anchor  1202  within the sleeve assembly  1200 . 
       FIG.  13    illustrates an isometric view of a portion of a sleeve assembly  1300 , in accordance with at least one example of this disclosure. The sleeve assembly  1300  can include translating locks to provide a low number of components. Any of the previously discussed sleeve assemblies can be modified to include such a lock assembly. 
     The sleeve assembly  1300  can include a body  1304 , a lock  1306 , and an actuator. The body  1304  can include arms  1320 A and  1320 B (including a boss  1330 ). The lock  1306  can include lock arms  1329 A and  1329 B. Also shown in  FIG.  13    is axis A and orientation indicators Proximal and Distal. 
     The sleeve assembly  1300  can be similar to the sleeve assemblies discussed above, except that the body  1304  can include the boss  1330  and can be flexible at a distal portion of the arm  1320 A such that when the lock arm  1329 A is moved to a locked position, the boss can engage a channel of an anchor head to retain the anchor within the sleeve assembly. When the lock arms are moved to the unlocked position (as shown with lock arm  1329 B), the arms  1320  can extend radially outward to release the anchor. Such an assembly can help reduce the number of total parts. 
       FIG.  14    illustrates a front view of a sleeve assembly, in accordance with at least one example of this disclosure. The sleeve assembly  1400  can include a sliding lock without an actuator. Any of the previously discussed sleeve assemblies can be modified to include such a sliding lock. 
     The sleeve assembly  1400  can include a body  1404  and a lock  1406 . The lock  1406  can include lock arms  1408  and  1410 , which can respectively include position locks  1412  and  1414 . Also shown in  FIG.  14    is axis A, directions D1 and D2, and orientation indicators Proximal and Distal. 
     The sleeve assembly  1400  can be similar to the sleeve assemblies discussed above, except that the lock arms  1408  and  1410  can be prevented from translating with respect to the body  1404  by the position locks  1412  and  1414 . A pinching force (shown as directions D1 and D2) can be applied to the position locks  1412  and  1414  to release the lock arms  1408  and  1410 , respectively, from the body  1404  to allow translation of the lock arms proximally  1408  and  1410  with respect to the body  1404 . Such an assembly can help reduce the number of total parts. 
       FIG.  15 A  illustrates a top view of a sleeve assembly  1500 , in accordance with at least one example of this disclosure.  FIG.  15 B  illustrates a side view of a portion of the sleeve assembly  1500 , in accordance with at least one example of this disclosure.  FIGS.  15 A and  15 B  are discussed below concurrently. The sleeve assembly  1500  can include a hex drive to allow a tool to be used to operate the actuator. Any of the previously discussed sleeve assemblies can be modified to include such a hex drive. 
     The sleeve assembly  1500  can include a body  1504 , a lock  1406 , and an actuator  1508 , which can include a hex drive  1510 . The sleeve assembly  1500  can be similar to the sleeve assemblies discussed above, except that the actuator  1508  can include the hex drive  1510  to allow a tool to be used to operate the actuator  1510 , which can help save time. In some examples, other drive engagements, such as slot, cross-recess, hexolobular, double hex, or the like. 
       FIG.  16    illustrates a cross section view of a portion of an anchor  1602  and sleeve assembly  1600 , in accordance with at least one example of this disclosure. The sleeve assembly  1600  can include a living hinge lock configured to engage a channel of the anchor. Any of the previously discussed sleeve assemblies can be modified to include such a living hinge lock. 
     The sleeve assembly  1600  can include a body  1604 , a lock  1606 , and an actuator. The body  1604  can include a lock arm  1620 A and a stop  1612 . The lock  1606  can include a spring lock  1626 , which can include a living hinge  1630 . The anchor  1602  can include a head  1610  having a channel  1611 . Also shown in  FIG.  16    is axis A, directions D1 and D2, and orientation indicators Proximal and Distal. 
     The sleeve assembly  1600  can be similar to the sleeve assemblies discussed above, except that the spring lock  1626  can include the living hinge  1630  which can fold or change shape in response to movement in direction D1 and contact between a distal portion of the spring lock  1626  and the stop  1612 , resulting in a compressive force. This compressive force can cause the living hinge to compress and move radially inward into the channel  1611  of the head  1610  to retain the anchor  1602  within the sleeve assembly. 
       FIG.  17    illustrates a cross section view of a sleeve assembly  1700 , in accordance with at least one example of this disclosure. The sleeve assembly  1700  can include a lock internal to the body, which can help protect the lock from external forces. Any of the previously discussed sleeve assemblies can be modified to include such an actuator and lock assembly. 
     The sleeve assembly  1700  can include a body  1704 , a lock  1706 , an actuator  1708 , and spring hooks  1726 . The sleeve assembly  1700  can be similar to the sleeve assemblies discussed above, except that the lock  1706  (including the lock arms) can be located within the body  1704  and can be movable therein. Such an internal lock can help reduce external interference of translation of the lock  1706 . 
       FIG.  18    illustrates a front view of a portion of an anchor  1802  and sleeve assembly  1800 , in accordance with at least one example of this disclosure. The sleeve assembly  1800  can include a lock actuated by insertion of the anchor  1802  into the sleeve. Any of the previously discussed sleeve assemblies can be modified to include such a lock assembly. 
     The sleeve assembly  1800  can include a body  1804 , a lock  1806 , and an actuator. The anchor  1802  and include a head  1810  having a channel  1811 . The lock can include a projection  1830 .  FIG.  18    also shows axis A, direction D1, and orientation indicators Proximal and Distal. 
     The sleeve assembly  1800  can be similar to the sleeve assemblies discussed above, except that the projection  1830  of the lock  1806  can be actuated to move radially inward by insertion of the anchor  1802  into the body  1804 , where the anchor  1810  can contact the lock  1806  to cause the projection  1830  to engage the channel  1811  to retain the head  1810  within the sleeve assembly  1800 . Such a lock can provide a sleeve without an actuator, which can help reduce the number of parts. 
     Notes and Examples 
     The following, non-limiting examples, detail certain aspects of the present subject matter to solve the challenges and provide the benefits discussed herein, among others. 
     Example 1 is a sleeve adapted to reinforce a bone anchor, the sleeve comprising: a body including a first sleeve arm and a second sleeve arm extending longitudinally along opposing sides of a longitudinal bore open at a distal end of the sleeve, the first and second sleeve arms separated by first and second sleeve slots, the first and second sleeve slots aligned across the longitudinal bore to receive a connecting member therethrough; a lock coupled to the body and releasably securable to a channel of a head of the bone anchor to secure the sleeve to the anchor; and an actuator connected to the body and operable between a locked and an unlocked position, the actuator configured to move the lock to engage the channel when the actuator is moved from the unlocked position to the locked position. 
     In Example 2, the subject matter of Example 1 optionally includes wherein the longitudinal bore is configured to receive extended tab portions of the head of the anchor therein. 
     In Example 3, the subject matter of Example 2 optionally includes wherein the first sleeve arm includes a first dovetail slot configured to receive a first extended tab of the anchor therein and wherein the second sleeve arm includes a second dovetail slot configured to receive a second extended tab of the anchor therein. 
     In Example 4, the subject matter of any one or more of Examples 1-3 optionally include wherein the first sleeve arm includes a first pocket located at a distal portion of the first sleeve arm and the second sleeve arm includes a second pocket located at a distal portion of the second sleeve arm, the lock movable within the first pocket and the second pocket to releasably engage the channel of the head of the anchor. 
     In Example 5, the subject matter of any one or more of Examples 1-4 optionally include wherein the actuator is a knob coupled to a proximal portion of the body, the knob rotatable to translate the lock relative to the body. 
     In Example 6, the subject matter of any one or more of Examples 1-5 optionally include a first spring hook secured to a distal portion of the first sleeve arm and a second spring hook secured to a distal portion of the second sleeve arm, the lock engageable with the first spring hook and the second spring hook to force the first spring hook and the second spring hook into the channel when the actuator is in the locked position. 
     In Example 7, the subject matter of any one or more of Examples 1-6 optionally include wherein the lock includes a first lock arm and a second lock arm, and wherein the first sleeve arm includes a first external slot configured to receive the first lock arm therein and wherein the second sleeve arm includes a second external slot configured to receive the second lock arm therein, the first lock arm and the second lock arm translatable within the first external slot and the second external slot, respectively. 
     In Example 8, the subject matter of Example 7 optionally includes a first spring hook secured to a distal portion of the first sleeve arm and a second spring hook secured to a distal portion of the second sleeve arm; wherein the first sleeve arm includes a first pocket located at a distal portion of the first sleeve arm and the second sleeve arm includes a second pocket located at a distal portion of the second sleeve arm, the first lock arm movable within the first pocket and the second lock arm movable within the second pocket to respectively engage the first spring hook and the second spring hook to force the first spring hook and the second spring hook into the longitudinal bore to engage the channel of the anchor to retain the anchor within the longitudinal bore when the actuator is in the locked position; and wherein the actuator is a knob coupled to a proximal portion of the body, the knob rotatable to translate the lock arms relative to the body. 
     In Example 9, the subject matter of Example 8 optionally includes wherein the first spring hook and second spring hook each include a barb extending radially inward to engage the channel of the anchor when the actuator is in the locked position. 
     In Example 10, the subject matter of Example 9 optionally includes wherein the first spring hook and second spring hook are biased radially outward from the longitudinal bore to limit engagement with the anchor when the actuator is in the unlocked position. 
     In Example 11, the subject matter of any one or more of Examples 8-10 optionally include wherein the first lock arm and the second lock arm are positioned radially outward of the first spring hook and the second spring hook, respectively, and wherein the first lock arm and second lock arm each include a tapered portion that is tapered radially at a distal portion of each of the first lock arm and the second lock arm. 
     In Example 12, the subject matter of Example 11 optionally includes wherein the tapered portion of the first lock arm and the tapered portion of the second lock arm are configured to translate into the pocket such that, as the first lock arm and the second lock arm translate distally, the pocket deflects each of the first lock arm and second lock arm, respectively, radially inward to contact the first spring hook and the second spring hook, respectively, to force the first spring hook and the second spring hook into the longitudinal bore to engage the channel of the anchor to retain the anchor within the longitudinal bore. 
     In Example 13, the subject matter of Example 12 optionally includes wherein the distal tip of each of the first spring hook and the second spring hook include a tip width that is wider than a width of a first hook channel and a second hook channel which respectively connect to the first pocket and the second pocket, to limit radially outward movement of the first spring hook and the second spring hook, respectively, from the first pocket and the second pocket. 
     In Example 14, the subject matter of any one or more of Examples 8-13 optionally include wherein each of the first spring hook and the second spring hook include a distal tip tapered radially inward to promote radially inward deflection of each of the first spring hook and the second spring hook through contact between each of the first spring hook and the second spring hook and the first pocket and the second pocket, respectively, as the first spring hook and the second spring hook are moved from an unlocked position to a locked position. 
     In Example 15, the subject matter of any one or more of Examples 8-14 optionally include wherein the cap is threadably couplable to the body and wherein the cap includes a plurality of fingers configured to engage a radially inner portion of the lock to couple the cap to a proximal portion of the lock. 
     In Example 16, the subject matter of any one or more of Examples 8-15 optionally include wherein the lock includes a proximal bore and the body includes a proximal slot alignable with the proximal bore, each configured to receive a pin therethrough to limit translation of the lock relative to the body. 
     Example 17 is an implant system for securing an anchor to a bone, the system comprising: an anchor comprising: a head open at a proximal end of the head; a shank extending distally from the head and configured to engage the bone; a first extension extending from a first breakaway portion coupling the first extension to the proximal end of the head; a second extension extending from a second breakaway portion coupling the second extension to the proximal end of the head; and a channel extending around at least a portion of the head, the channel located distal of the first breakaway portion and the second breakaway portion; and a sleeve adapted to reinforce the anchor, the sleeve comprising: a body including a first sleeve arm and a second sleeve arm together extending longitudinally to form a longitudinal bore open at a distal end of the sleeve to receive the head therein, the first and second sleeve arms separated by a first sleeve slot and a second sleeve slot to receive a connecting member therethrough; a lock coupled to the body and releasably engageable with the channel of the head to secure the sleeve to the anchor; and an actuator connected to the body and operable between a locked and an unlocked position, the actuator configured to move the lock to engage the channel when the actuator is moved from the unlocked position to the locked position. 
     In Example 18, the subject matter of Example 17 optionally includes wherein the first sleeve arm includes a first pocket located at a distal portion of the first sleeve arm and the second sleeve arm includes a second pocket located at a distal portion of the second sleeve arm, the lock movable within the first pocket and the second pocket to releasably engage the channel of the head of the anchor. 
     In Example 19, the subject matter of Example 18 optionally includes a first spring hook secured to a distal portion of the first sleeve arm and a second spring hook secured to a distal portion of the second sleeve arm, the lock engageable with the first spring hook and the second spring hook to force the first spring hook and the second spring hook into the channel when the actuator is in the locked position. 
     In Example 20, the subject matter of Example 19 optionally includes wherein the first spring hook and second spring hook each include a barb extending radially inward to engage the channel of the anchor when the actuator is in the locked position, and wherein the first spring hook and second spring hook are biased radially outward from the longitudinal bore to limit engagement with the anchor when the actuator is in the unlocked position. 
     In Example 21, the apparatuses or methods of any one or any combination of Examples 1-20 can optionally be configured such that all elements or options recited are available to use or select from. 
     The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein. 
     In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls. 
     In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. 
     The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined \with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.