Patent Publication Number: US-2021186573-A1

Title: Surgical band clamp system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/391,724 filed Apr. 23, 2019, which is a continuation of U.S. patent application Ser. No. 15/368,279 filed Dec. 2, 2016, the contents of which are entirely incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates generally to medical devices, more specifically to the field of spinal surgery and spinal fixation devices. Such devices as well as systems and methods for use therewith are described. 
     BACKGROUND 
     The spine is critical in human physiology for mobility, support, and balance. The spine protects the nerves of the spinal cord, which convey commands from the brain to the rest of the body, and convey sensory information from the nerves below the neck to the brain. Even minor spinal injuries can be debilitating to the patient, and major spinal injuries can be catastrophic. The loss of the ability to bear weight or permit flexibility can immobilize the patient. Even in less severe cases, small irregularities in the spine can put pressure on the nerves connected to the spinal cord, causing devastating pain and loss of coordination. 
     Surgical procedures on the spine often include the immobilization of two or more vertebra. Immobilizing the vertebrae may be accomplished in many ways (e.g. fixation plates and pedicle screw systems). One of the most common methods for achieving the desired immobilization is through the application of bone anchors (most often introduced into the pedicles associated with the respective vertebra to be fixed) that are then connected by rigid rods locked to each pedicle screw. These pedicle screw systems are very effective. Pedicle screws generally include an anchor component and a rod-housing component. 
     However, in some cases screws are not the best choice for a spinal bone anchor. Some bone structures might not have sufficient mechanical strength or integrity to withstand penetration by the screw, due to injury or age-related deterioration. In some cases it may be desirable for the bone anchor to have a small degree of freedom of movement relative to the bone structure, which cannot be provided by bone screws. Still in some other cases it may be desirable to provide stability to an adjacent vertebra or multiple vertebrae adjacent to a vertebra being immobilized with a fixation construct, yet without fully immobilizing the adjacent vertebra. As a result, there is a need in the art for alternative fastening means for bone anchors. 
     SUMMARY 
     The needs above, as well as others, are addressed by embodiments of a connector system for securing a spinal rod to a bone structure via a band clamp described in this disclosure (although it is to be understood that not all needs described above will necessarily be addressed by any one embodiment). 
     Dual-lock connectors are provided with separate locking mechanisms for the band that connects the connector to the bone structure and for the spinal rod. A general embodiment of the dual lock connector comprises: a rod channel dimensioned to admit the spinal rod; a locking cap channel intersecting the rod channel; a locking cap in the locking cap channel; a pair of band channels each having a band entrance and a band exit; and a clamping mechanism that modulates the width of at least a portion of each of the pair of band channels. 
     A single-lock connector is provided that has one locking mechanism for the band that connects the clamp to the bone structure and for the spinal rod. A general embodiment of the single-lock connector comprises a base having a band entry channel and a band friction surface; a threaded post fastened to the base, such that the base cannot translate in the distal/proximal direction relative to the threaded post; a nut on the threaded post; an upper housing section between the nut and the base, having an upper rod channel portion; and a lower housing section between the upper housing section and the base, having a lower rod channel portion that forms a partially cylindrical rod channel in combination with the upper rod channel portion, and a band friction counter-surface that forms a pair of band exit channels contiguous with the band entry channel in combination with the base; wherein tightening the nut imparts compressive force on the upper section with a distal vector, which causes the upper section to exert compressive force on the lower section with a distal vector, which in turn causes the lower section to exert compressive force on the base with a distal vector. 
     A tensioning instrument for use with the connectors described above is provided. The tensioning instrument functions to control the tension on the band connecting the connector to the bone and can be used through relative small surgical incisions. A general embodiment of the tensioning instrument comprises a distal end and a proximal end; a connector engagement feature on the distal end; a band holder configured to reversibly connect to a band and restrict longitudinal translation of the band relative to the band holder, the band holder comprising a band connection ring comprising a pair of band slots for holding the flexible band, and a band locking ring abutting the band connection ring, capable of at least limited rotation relative to the band connection ring, comprising a pair of indentations sufficiently deep to allow the flexible band to enter and exit the pair of band slots without friction from the band locking ring when the indentations are aligned with the band slots, and a pair of surfaces that exert friction on the flexible band sufficient to prevent longitudinal translation of the flexible band relative to the band holder when aligned with the pair of band slots; and a band holder translation mechanism to control the translation of the band holder relative to the connector engagement feature. 
     The band clamp and associated band may be used as an alternative means to connect a spinal rod to a bone. For example, the band may be passed under the lamina to form a loop therearound with the band clamp sitting above the lamina and coupled to the rod. The band could similarly be looped around a transverse process or rib, for example. Alternatively, the connector and associated band may used to strengthen, reconstruct, and/or otherwise emulate ligaments that may have been damaged or removed during implantation of the fixation construct. For example, a band connected to the connector may be wrapped around the facet, transverse process, lamina, rib and/or spinous process to provide further stability to the construct. In still another alternative, the connector and associated band may be used to provide additionally stability to the spine adjacent a fixation construct. For example, the band may be wrapped around (or, through a hole formed therein) one or more of a lamina(s), transverse process(s), spinous process(s), and rib(s) of one or more vertebrae proximal to the end of the construct. 
     A method of anchoring a spinal rod housing to a bone structure with a band clamp is provided. A general embodiment of the method comprises positioning a flexible band around a bone structure to make contact between a middle portion of the band and said bone structure; connecting a pair of terminal portions of the flexible band to a connector, the connector comprising a pair of band channels and the spinal rod housing, wherein each of the pair of terminal portions is in a respective band channel; increasing tension on the flexible band in an amount sufficient to cause contact between the connector and the bone structure and sufficient to restrict movement of the connector relative to the bone structure; locking each of the terminal portions of the flexible band the connector by narrowing each of the band channels to prevent release of the tension; and immobilizing the spinal rod in the spinal rod housing to prevent movement of the connector relative to the spinal rod. 
     The above presents a simplified summary in order to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview. It is not intended to identify key or critical elements or to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 . A perspective view of a dual-lock embodiment of the connector. 
         FIG. 2 . An alternative perspective view of the embodiment of the connector shown in  FIG. 1 . 
         FIG. 3A . A side plan view of the connector shown in  FIG. 1  in which the band clamping mechanism is in an open position. 
         FIG. 3B . A side plan view of the connector shown in  FIG. 1  in which the band clamping mechanism is in a closed position. 
         FIG. 4 . A side cross-sectional view of the connector shown in  FIG. 1 . 
         FIG. 5A . A front plan view of the connector shown in  FIG. 1  in which the band clamping mechanism is in an open position. 
         FIG. 5B . A front plan view of the connector shown in  FIG. 1  in which the band clamping mechanism is in closed position. 
         FIG. 6 . A bottom plan view of the connector shown in  FIG. 1 . 
         FIG. 7 . A top plan view of the connector shown in  FIG. 1 . 
         FIG. 8 . A perspective view of an alternative embodiment of the connector having a closed rod channel. 
         FIG. 9 . A perspective view of a single-lock embodiment of the connector. 
         FIG. 10 . An alternative perspective view of the embodiment of the connector shown in  FIG. 9 . 
         FIG. 11 . A side plan view of the connector shown in  FIG. 9 . 
         FIG. 12 . A side cross-sectional view of the connector shown in  FIG. 9 . 
         FIG. 13 . A front plan view of the connector shown in  FIG. 9 . 
         FIG. 14 . A bottom plan view of the connector shown in  FIG. 9 . 
         FIG. 15 . A top plan view of the connector shown in  FIG. 9 . 
         FIG. 16 . A perspective view of an embodiment of the tensioning instrument. 
         FIG. 17 . An alternative perspective view of the embodiment of the tensioning instrument shown in  FIG. 16 . 
         FIG. 18 . A side plan view of the embodiment of the tensioning instrument shown in  FIG. 16 . 
         FIG. 19 . A front plan view of the embodiment of the tensioning instrument shown in  FIG. 16 . 
         FIG. 20 . A side cross-sectional view of the embodiment of the tensioning instrument shown in  FIG. 16 . 
         FIG. 21 . A bottom (distal) plan view of the embodiment of the tensioning instrument shown in  FIG. 16 , showing detail of the connector engagement features on the instrument. 
         FIG. 22 . A partial side view of the embodiment of the tensioning instrument shown in  FIG. 16 , in which the indentations on the band locking ring are in alignment with the band slots on the band connection ring, to allow the flexible band to enter and exit the pair of band slots without friction from the band locking ring. 
         FIG. 23 . A partial side view of the embodiment of the tensioning instrument shown in  FIG. 16 , in which the friction surfaces on the band locking ring are in alignment with the band slots on the band connection ring (and the indentations are not in alignment with the band slots), which would exert friction on the band. 
         FIG. 24 . A partial cross-sectional side view of the distal part of the embodiment of the tensioning instrument shown in  FIG. 16 , showing detail of the connector engagement feature. 
         FIG. 25 . A partial cross-sectional side view of the distal part of the embodiment of the tensioning instrument shown in  FIG. 16 , showing detail of the connector engagement feature in the unlocked configuration. 
         FIG. 26 . A partial cross-sectional side view of the distal part of the embodiment of the tensioning instrument shown in  FIG. 16 , showing detail of the connector engagement feature in the locked configuration. 
         FIG. 27 . A cross-sectional front view of an embodiment of connector showing bands in the band channels. 
         FIG. 28 . A perspective view of the embodiment of the connector as shown in  FIG. 8  showing bands in the band channels. 
         FIG. 29 . A perspective view of the embodiment of the connector as shown in  FIG. 9  showing bands in the band channels. 
         FIG. 30 . A perspective view of the embodiment of the connector as shown in  FIG. 1  with bands in the band channels. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative embodiments of a surgical band clamp system are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as a compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The surgical band clamp system disclosed herein boasts a variety of inventive features and components that warrant patent protection, both individually and in combination. 
     A dual-lock version 400 of the connector  100  is shown in  FIGS. 1-7 . As shown, the connector  100  comprises: a rod channel  110  dimensioned to admit the spinal rod  120 ; a locking cap channel  140  intersecting the rod channel  110 ; a locking cap  130  in the locking cap channel  140 ; a pair of band channels  150  each having a band entrance  152  and a band exit  154 ; and a clamping mechanism  180  that modulates the width of at least a portion of each of the pair of band channels  150 . The connector  100  can be roughly divided into a rod housing section  170  that contains the rod channel  110 , locking cap channel  140 , and locking cap  130 ; and a band clamp section  126  that contains the pair of band channels  150  and the clamping mechanism  180 . In the illustrated embodiments the rod channel  110  is separate from the band channels  150 , and does not intersect with either of them. The dual-lock embodiments  400  have the advantage of allowing the tension on the band  350  to be adjusted regardless of whether the connector  100  has been secured to the rod  120  (and vice versa). 
     The locking cap  130  and locking cap channel  140  each have complementary engagement features. In a specific embodiment, the locking cap  130  comprises a screw thread  128  on its exterior and the locking cap channel  140  comprises complementary threads  144 . The engagement features on the locking cap  130  and locking cap channel  140  function to guide the locking cap  130  in the distal direction to contact and exert distal force on the spinal rod  120 . In the context of this disclosure the term “distal” refers to the direction away from the user (e.g., surgeon) during implantation of the connector  100 , whereas “proximal” refers to the opposite direction toward the user. In some cases the locking cap  130  or locking cap channel  140  (or both) will contain locking features to prevent the locking cap  130  from translating in the proximal direction once full reduced against the spinal rod  120 . 
     In the embodiment illustrated in  FIGS. 1-7  the band clamp section  126  contains a pair of band clamp channels  150  which share a common band entrance  152  and each of which has a distinct band exit  154 . In use, the two terminal sections  210  of the band  350  are passed through the distal band entrance  202  after being wrapped around the bone structure  14  (e.g. a lamina), and each of the two terminal sections  210  is threaded through the band channels  150  to its respective band exit  154  (to one side or another). The illustrated clamping mechanism  180  is formed by two opposing bodies that together define part of the band channels  150 , and can be repositioned to modulate the width of the band channels  150  and exert friction against the bands when in place. The two opposing bodies are a base  220  and a separate compressing body  230 . In the illustrated embodiment the base  220  is integral with the rod housing section  170 , which has the advantage of simplicity in manufacturing. However, the base  220  and the rod housing section  170  may be fabricated separately and assembled, as necessary for the particular application. The proximal surface of the base  220  functions as a compressing surface  240  to counter force exerted by the compressing body  230 . A mechanism is provided to exert force with a distal vector on the compressing body  230 , which in turn exerts force with a distal vector on the base  220  (and on the band if it is present in the band channel  150 ). In the illustrated embodiment, this mechanism comprises a threaded post  260  that does not translate along the longitudinal axis relative to the base  220  and a nut  270  on the threaded post  260  that is positioned to press on the compression body  230  when the nut  270  is tightened on the threaded post  260 . By tightening the nut  270  the compressing body  230  is moved toward the base  220 , and the two band channels  150  are narrowed. This action can be seen by comparing the connector  100  with the clamping mechanism  180  in the open position in  FIGS. 3A and 5A  to the connector  100  with the clamping mechanism  180  in the closed position in  FIGS. 3B and 5B . Ultimately the band will be in contact with both the base  220  and the compressing body  230 , and the band  350  can be locked in place by further tightening the nut  270  on the post  260 . 
     The embodiment of the connector  100  shown in  FIGS. 1-7  is constructed from three separate pieces: a main body  280  that contains the rod channel  110 , the locking cap channel  140 , the base  220 , and the threaded post  260 ; the nut  270  on the threaded post  260 ; and the compressing body  230  around the threaded post  260  between the nut  270  and the base  220 . In order for the connector  100  to function correctly these three pieces must translate relative to one another, and this can be accomplished by providing these components separately. Although in the illustrated embodiments each of the three pieces is a unitary structure, each could be constructed from at least two smaller pieces fastened together. 
     In some embodiments of the connector  100  the nut  270  is a locknut. The locknut is a nut with some means of resisting removal or loosening due to vibration and/or torque. In some embodiments of the connector  100  the locknut is a nut  270  used in conjunction with a spring lock washer (thus the nut on its own is not resistant to loosening). In further embodiments the locknut is structured to resist loosening on its own; examples of such locknuts include a castellated nut, distorted thread locknut, centerlock nut, elliptical offset locknut, toplock nut, Philidas nut, interfering thread nut, tapered thread nut, jam nut, jet nut, Keps nut, plate nut, polymer insert nut, security lock nut, serrated face nut, serrated flange nut, speed nut, split beam nut, and palnut. 
     The exterior of the housing  170  near the proximal end of the locking cap channel  140  may include instrument attachment features  160  for coupling to various tools useful during implantation of the bone anchor  10  and associated fixation construct  20  (e.g., inserters, reducers, and other such tools as are known in the art). In the specific embodiment shown in  FIGS. 1-8 , the attachment features  160  comprise four depressions  164  near the corners. Together the four depressions  164  allow a tool to connect to the connector  100  in such a way that the tool will neither translate longitudinally nor rotate circumferentially while attached. Other configurations of course may be used. 
     The rod channel  110  is open on one lateral side in the embodiments of the connector  100  shown in  FIGS. 1-7 . This allows the spinal rod  120  to be loaded into the rod channel  110  from a lateral direction, thus having the advantage of ease of installation. However, other configurations of the rod channel  110  are possible. Another example is shown in  FIG. 8 .  FIG. 8  shows an embodiment of the connector  100  in which the rod channel  110  is open only at longitudinal ends  118  (i.e., along the longitudinal axis of the spinal rod  120 ), and is closed on all lateral sides. Such embodiments of the connector  100  have the advantage of enhanced stability once the rod  120  is in place and potentially smaller size. 
     An alternative general embodiment of the connector  100  is shown in  FIGS. 9-15 . The “single-lock” connector  370  unifies the band clamping mechanism  180  and the rod clamping mechanism  190 . This has the advantage of allowing the band  350  to be locked in place and the rod  120  to be locked in place in a single step. As in the embodiments described above, the single-lock clamp  380  comprises a base  220  and a threaded post  260  fastened to the base  220 ; the term “fastened” when referring to the post  260  and the base  220  may include embodiments in which the post  260  and base  220  are part of the same integral structure. In all contemplated embodiments the threaded post  260  and the base  220  cannot translate in the longitudinal axis relative to one another. In the illustrated embodiment the base  220  comprises a single band entrance  152  for both band channels  150 , and two band exits  154 . 
     A nut  270  may be engaged to the threaded post  260 , which may be any version of a nut  270  disclosed as suitable above for the dual-lock embodiments  400 . 
     The single-lock embodiment  300  comprises a lower housing section  310 , which functions like the compressing body  230  in the dual-lock embodiments  400  in that it moves relative to the base  220  to modulate the width of the band channels  150  and exert distal force on the band segments  126  when they are present. In the illustrated embodiment the lower housing section  310  is placed around the threaded post  260 ; it contains an aperture  330  to admit the post  260  (not shown). The lower housing section  310  forms the distal part of the rod channel  110 . 
     Between the lower housing section  310  and the nut  270  is an upper housing section  32 . The upper housing section  32  forms the proximal part of the rod channel  110 . In the illustrated embodiment the upper housing section  32  is placed around the threaded post  260 , and has an aperture  340  to admit the post  260 . 
     The upper housing section  320 , lower housing section  310 , and base  220  are all free to translate along the longitudinal axis relative to one another when the nut  270  has not been tightened (the connector  100  is referred to as “loose” in this state). While the connector  100  is loose, the width of the rod channel  110  may be increased for the easy insertion of the spinal rod  120 . Once the spinal rod  120  is inserted into the rod channel  110 , the nut  270  is tightened, causing the rod channel  110  to narrow until the rod  120  is locked into place. Likewise, while the connector  100  is loose the terminal regions  360  of the band can be pulled through the band channel  150  without significant friction being exerted by the lower housing section  310  and the base  220 . Once the band  350  has been threaded through the band channel  150  and adjusted to the desired tension, the nut  270  is tightened causing the band  350  to be clamped between the base  220  and the lower housing section  310 . 
     A tensioning instrument  500  for use with the system is also provided; an embodiment of which is shown in  FIGS. 16-26 . The tensioning instrument  500  allows tension on the band  350  between the bone structure  14  and the connector  100  to be precisely modulated without creating a large incision during-surgery. A general embodiment of the tensioning instrument  500  comprises a distal end  510  and a proximal end  520 ; a connector engagement feature  530  on the distal end  510 ; a band holder  540  configured to reversibly connect to a band  350  and restrict longitudinal translation of the band  350  relative to the band holder  540 , the band holder  540  comprising a band connection ring  584  comprising a pair of band slots  550  for holding the flexible band  350 ; and a band locking ring  552  abutting the band connection ring  584 , capable of at least limited rotation relative to the band connection ring  584 , comprising a pair of indentations  590  sufficiently deep to allow the flexible band  350  to enter and exit the pair of band slots  550  without friction from the band locking ring  552  when the indentations  590  are aligned with the band slots  550 , and a pair of surfaces that exert friction on the flexible band  350  sufficient to prevent longitudinal translation of the flexible band  350  relative to the band holder  540  when aligned with the pair of band slots  550 ; and a band holder translation mechanism  700  to control the translation of the band holder  540  relative to the connector engagement feature  530 . The instrument  500  is generally elongate in shape, and may further comprise an internal lumen  560  running from the proximal end  520  to the distal end  510  and dimensioned to admit any of various useful tools, such as a nut driver  598 . 
     The connector engagement feature  530  will be designed to restrict or prevent the degree of movement between the tensioning instrument  500  and the connector  100  when engaged. In this context “restricted” movement refers to a reduction in possible movement that is significant, but not necessarily complete or absolute. The connector engagement feature  530  may include a clamp locking mechanism  50  capable of reversibly locking the connector  100  to the connector engagement feature  530  to restrict both translation and deflection of the tensioning instrument  500  relative to the connector  100 , granting stability during the tensioning process. Some embodiments of the connector  100  may comprise one or more instrument attachment features  160 , as explained above. Exemplary embodiments of the tensioning instrument  500  may comprise a connector engagement feature  530  that engages with an instrument engagement feature  160  on the connector  100 . 
     A specific example of a connector engagement feature  530  is shown in  FIGS. 24-26 . A clamp locking mechanism  50  is present. The clamp locking mechanism  50  in this embodiment includes an internal ramp structure  60  on an internal surface  504  of the distal end  510  of the instrument  500  that decreases in width in the proximal direction. As can be best seen in  FIGS. 25-26 , the outermost housing  508  of the reduction instrument  500  has an internal contour that widens in the distal direction and narrows in the proximal direction. This takes the form of a “ramp” ( 60 ) between a wider region at the distal end  510  and a narrower region just proximal to the ramp  60 . The clamp locking mechanism  50  shown also comprises a boot member  600  that translates longitudinally relative to the outer housing  508 . The boot has an internal side  620  and an external side  640 , and is dimensioned to internally accept the proximal end  104  of the connector  100 . The boot member  600  also has a plurality of detent members  630  (balls as shown in the figures) each in a cavity that allows the detent member  610  to translate radially from the outer side  640  of the boot member  600  to the inner side  620  of the boot member  600 . The detent members  610  are positioned in the cavities such that they translate longitudinally with the boot member  600 .  FIG. 25  shows the locking mechanism  50  in its unlocked configuration, in which the boot member  600  is positioned so that the detent members  610  contact the distal, broader part of the ramp formation  70 .  FIG. 26  shows the locking mechanism  50  in its locked configuration, in which the boot member  600  is positioned so that the detent members  610  contact the narrower proximal portion of the ramp formation  80 , which causes the detent members  610  to translate inward radially. This allows the detent members  610  to engage depressions in the proximal end  104  of a connector  100  when the connector  100  is pressed against the boot member  600 . The boot member  600  can be translated longitudinally by any suitable mechanism. For example, the boot  600  may be coupled to a thumb wheel  750  on a spiral track, such that rotation of the thumb wheel  750  causes translation of the thumb wheel  750  and the boot longitudinally. 
     The band slots  550  on the band connection ring  584  will be positioned to provide balanced tension to the bands. In a specific embodiment of the instrument  500 , the band slots  550  are positioned approximately 180.degree. from one another on the band connection ring  584 . Such an instrument  500  has the advantage of providing high stability when the band  350  is under high tension. 
     The band connection ring  584  and the band locking ring  552  work together to allow tension on the band to be maintained without constant human intervention. Some previous approaches require that a user maintain tension manually while band tension is locked on the connector  100 . The inventive instrument  500  provides a locking mechanism on the instrument  500  itself that it simple for the operator to use and does not require manual strength. When the band slots  550  are aligned with the indentations  590 , there is no obstruction to pulling the bands through the slots (or loosening them through the slots). As a result the bands can be pulled to increase tension while the band slots  550  are aligned with the indentation. The configuration in which the indentations  590  are aligned with the band slots  550  is shown in  FIG. 22 . Once sufficient tension has been achieved, the band locking ring  552  is rotated so that the indentations  590  are no longer aligned with the band slots  550 ; this wedges the band between the band locking ring  552  and the top of the band slot  550 . Some embodiments of the band connection ring  584  comprise gripping or high-friction elements at the exit  154  of the band channel  150 , such as the teeth shown in  FIGS. 22 and 23 . The configuration in which the indentations  590  are not aligned with the band slots  550  is shown in  FIG. 23 . 
     Once the band  350  is locked into place relative to the instrument  500 , tension is placed on the band  350  by translating the band holder  540  in the proximal direction. An example of the translation mechanism  700  can be seen in  FIG. 20 . In that illustrated embodiment the band holder translation mechanism  700  comprises a threaded shaft  710  that is free to rotate relative to the band holder  540 , and a threaded surface  720  on the band holder  540  engaged to the threaded shaft  710 , such that rotation of the threaded shaft  710  results in longitudinal translation of the band holder  540 . The threaded shaft  710  is rotated using a knob  740  on the proximal end of the device. The threaded surface  720  on the band holder  540  is a threaded plate  730  on the interior surface  548  of the band holder  540  that is engaged to the threaded shaft  710 , and attached to the band holder  540  such that the threaded plate  730  and the band holder  540  translate together longitudinally. As can be seen in  FIG. 20 , the threaded shaft  710  in the illustrated embodiment comprises external threads and is positioned to the interior of the band holder  540 . 
     A method is provided for anchoring a spinal rod  120  to a bone structure  14  using the systems described above. A general embodiment of the method comprises: positioning a flexible band around the bone structure  14  to make contact between a middle portion of the band and said bone structure  14 ; connecting a pair of terminal portions of the flexible band to a connector  100 , the connector  100  comprising a pair of band channels  150  and the spinal rod housing  170 , wherein each of the pair of terminal portions is in a respective band channel  150 ; increasing tension on the flexible band in an amount sufficient to cause contact between the connector  100  and the bone structure  14  and sufficient to restrict movement of the connector  100  relative to the bone structure  14 ; locking each of the terminal portions of the flexible band the connector  100  by narrowing each of the band channels  150  to prevent release of the tension; and immobilizing the spinal rod  120  in the spinal rod housing  170  to prevent movement of the connector  100  relative to the spinal rod  120 . The connector  100  may be, without limitation, any embodiment of the connector  100  described above. 
     The flexible band  350  is of suitable construction for implantation in vivo. It is constructed from biocompatible materials, such as woven polyethylene terephthalate fiber. The band is elongate in shape, having a middle section and two terminal sections. In use the middle section is looped or wrapped around the bone structure  14 , and the terminal sections are threaded through the band channels  150  of the connector  100 . 
     Tension is increased on the band to produce the desired degree of restriction of motion between the connector  100  and the bone. The tension may be produced by pulling the terminal sections away from the connector  100 , either manually or using a tensioning instrument  500 . For example, the tension may be produced using any embodiment of the tensioning instrument  500  described above. 
     The terminal portions of the band are “locked” to the connector  100  such that the tension on the band between the connector  100  and the bone structure  14  is maintained indefinitely. Each terminal portion of the band is locked into a separate band channel  150 . In embodiments in which the two terminal portions share portions of their respective band channels  150 , locking occurs in portions of the channels that are separate from one another. This has the advantage of preventing interference between the two terminal portions of the band from compromising the locking force (i.e., friction) on one or both of the band portions. 
     The rod  120  is immobilized by any suitable means. For example, the rod  120  may be immobilized in the connector  100  using a locking cap  130  arrangement as described above for the dual-lock embodiments  400  of the connector  100 ; or alternatively the rod  120  may be immobilized in the connector  100  using a rod channel  110  with two sections (e.g., an upper housing section  320  and a lower housing section  310 ) as described above for the single-lock embodiments  300  of the band channel  150 . 
     Some embodiments of the method have the advantage of allowing the tension to be increased on the band  350  without affecting the tension or compression exerted by the band or the connector  100  on the spinal rod  120 . Unlike some prior approaches, the current method may be designed to allow the band tensioning step to be distinct from the rod  120  immobilizing step. This has the advantage of allowing the rod  120  to be inserted, adjusted, and immobilized relative to the connector  100  after the connector  100  has been secured to the bone  14  using the band. In some further embodiments, the band  350  does not contact the spinal rod  120  when the band  350  is connected to the connector  100 . 
     It is to be understood that any given elements of the disclosed embodiments of the invention may be embodied in a single structure, a single step, a single substance, or the like. Similarly, a given element of the disclosed embodiment may be embodied in multiple structures, steps, substances, or the like. 
     In an alternative method, the connector  100  may be attached to a rod  120  near the proximal end of a fixation construct  20 . The band may be wrapped around (or, through a hole formed therein) one or more of a lamina(s), transverse process(s), spinous process(s), and rib(s) of one or more vertebrae proximal to the end of the construct and then tensioned and locked to the connector  100  as previously described. This configuration may provide additionally stability to the spine adjacent the construct while reducing the forces that may help contribute to adjacent segment disease. 
     The foregoing description illustrates and describes the processes, machines, manufactures, compositions of matter, and other teachings of the present disclosure. Additionally, the disclosure shows and describes only certain embodiments of the processes, machines, manufactures, compositions of matter, and other teachings disclosed, but, as mentioned above, it is to be understood that the teachings of the present disclosure are capable of use in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the teachings as expressed herein, commensurate with the skill and/or knowledge of a person having ordinary skill in the relevant art. The embodiments described hereinabove are further intended to explain certain best modes known of practicing the processes, machines, manufactures, compositions of matter, and other teachings of the present disclosure and to enable others skilled in the art to utilize the teachings of the present disclosure in such, or other, embodiments and with the various modifications required by the particular applications or uses. Accordingly, the processes, machines, manufactures, compositions of matter, and other teachings of the present disclosure are not intended to limit the exact embodiments and examples disclosed herein. Any section headings herein are provided only for consistency with the suggestions of 37 C.F.R. sctn. 1.77 or otherwise to provide organizational queues. These headings shall not limit or characterize the invention(s) set forth herein.