Patent Description:
The <CIT>, <CIT> and <CIT> disclose further spinal fixation assemblies.

The present invention is defined in the independent claims <NUM> and <NUM> while preferred embodiments are set forth in the dependent claims.

According to the present invention, a spinal fixation assembly comprises a tether configured to engage a spinal feature of a patient's spine,wherein the tether is devoid of locking teeth;an inner coupling piece, wherein the inner coupling piece comprises a slot configured to receive and engage a rod therein;an outer coupling piece configured to be coupled with the inner coupling piece in a nesting fashion;a first passage configured to receive a first portion of the tether, wherein the first passage is defined by an inner surface of the outer coupling piece and an outer surface of the inner coupling piece, wherein the first passage is configured such that the tether can be clamped in between the inner surface and the outer surface so as to allow the tether to move through the first passage in a first direction and lock the tether in place so as to at least substantially prevent the tether from moving through the first passage in a second direction opposite from the first direction.

Disclosed herein are various embodiments of tether clamping assemblies, along with related bone fixation assemblies with which the tether clamping assemblies may be used, along with various other devices. In preferred embodiments, the tether clamping assemblies may be configured to both receive and lock one or more tether portions therein and also to be coupled with a fixation member, such as an elongated rod. Thus, the features disclosed herein are particularly suitable for use in connection with spinal fixation. However, it is contemplated that the features disclosed herein may also be used in other medical implants and/or devices, as disclosed in greater detail below.

According to the invention, the assembly comprises a tether configured to engage a spinal feature of a patient's spine, such as a spinous process, transverse process, and/or spinal lamina. The tether is devoid of locking teeth. Thus, in some such embodiments, the tether may be smooth, or at least substantially smooth. In some embodiments, the tether may comprise a flattened tether having a rectangular cross-sectional shape. In some embodiments, the tether may comprise opposing surfaces that are at least substantially uniform in roughness. In some such embodiments, both opposing surfaces may be smooth, or at least substantially smooth.

The spinal fixation assembly comprises a tether clamping assembly, which comprises a first coupling piece and a second coupling piece configured to be coupled with the first coupling piece. The first coupling piece comprises an inner coupling piece, the second coupling piece comprises an outer coupling piece, and the inner coupling piece is configured to be nested or otherwise received within the outer coupling piece.

The tether clamping assembly comprises a first passage configured to receive a first portion of the tether. One or both passages may be configured to provide for a wedge lock of the tether therein. This may be provided, for example, by providing opposing surfaces defining the passage(s), which surfaces may be part of inner and outer surfaces of an outer and inner coupling piece of the assembly, respectively, that are tapered in the same direction relative to a central axis of the tether clamping assembly, which may coincide with the axis of a cap and/or set screw in some embodiments. In some embodiments, the respective angles of the two surfaces may differ slightly to enhance this wedge lock. Alternatively, however, the two surfaces may taper at the same, or at least substantially the same, angle.

The first passage may be defined by a first surface and a second surface, wherein the first surface comprises a surface roughness greater than a surface roughness of the second surface, and wherein the first passage is configured such that the tether can be clamped in between the first surface and the second surface so as to allow the tether to move through the first passage in a first direction and lock the tether in place so as to at least substantially prevent the tether from moving through the first passage in a second direction opposite from the first direction.

Some embodiments may further comprise a second passage configured to receive a second portion of the tether to define a tether loop for engaging the spinal feature. In some such embodiments, the second passage may also be defined by a first surface and a second surface, wherein the first surface of the second passage comprises a surface roughness greater than a surface roughness of the second surface of the second passage.

In some embodiments, the first surface of one or both passages may be formed on an inner wall of the outer coupling piece, and the second surface may be formed on an outer wall of the inner coupling piece. To provide a desired surface roughness differential between the two opposing surfaces of one or both of the passages, the first surface may comprise a plurality of projections configured to engage the tether. The plurality of projections may be defined by, for example, a plurality of elongated grooves and/or a plurality of teeth. In some embodiments, the second surface of one or both passages may be smooth.

Further according to the invention, the assembly comprises a tether configured to engage a bone, such as a portion of a patient's spine. The assembly further comprises an inner coupling piece and an outer coupling piece configured to receive the inner coupling piece. A first passage is at least partially defined by an inner surface of the outer coupling piece and an outer surface of the inner coupling piece and configured to receive the tether therethrough. The first passage is configured such that the tether can be clamped in between the inner surface and the outer surface so as to allow the tether to move through the first passage in a first direction and lock the tether in place so as to at least substantially prevent the tether from moving through the first passage in a second direction opposite from the first direction. At least one of the inner surface and the outer surface comprises a plurality of projections configured to engage the tether. Alternatively, one of the inner surface and the outer surface may otherwise be contoured and/or surface roughened to provide a frictional differential.

In some embodiments, only one of the inner surface and the outer surface comprises a plurality of projections configured to engage the tether.

Some embodiments may further comprise a second passage at least partially defined by an inner surface of the outer coupling piece and an outer surface of the inner coupling piece. The second passage may be configured to receive a second portion of the tether therethrough so as to define a tether loop for engaging the bone. Similar to the first passage, in some embodiments, the second passage may be configured such that the tether can be clamped in between the inner surface of the second passage and the outer surface of the second passage so as to allow the tether to move through the second passage in a first direction and lock the tether in place so as to at least substantially prevent the tether from moving through the second passage in a second direction opposite from the first direction.

Some embodiments may further comprise a cap. In some such embodiments, the cap may be configured to engage the inner coupling piece, such as by threadably engaging the inner coupling piece. In some embodiments in which the cap is threaded, the cap may be configured to engage a threaded opening formed on the inner coupling piece. The cap may also, or alternatively comprise a flange, which may be configured to engage the outer coupling piece.

In a specific example of method for fixation of a tether to an anatomical feature, the method may comprise extending a flexible tether in a loop around an anatomical feature of a patient, such as a spinal feature. An elongate member, such as a rod, may be coupled with a clamping assembly. A first end of the flexible tether may be threaded through a first passage of the clamping assembly. The first passage may be defined by a first pair of opposing surfaces, preferably having distinct surface roughnesses. In some implementations, a second end of the flexible tether opposite from the first end may be threaded through a second passage defined by a second pair of opposing surfaces also preferably having distinct surface roughnesses. In some implementations, the steps of threading the first end of the flexible tether through the first passage and threading the second end of the flexible tether through the second passage lock the flexible tether in place about the anatomical feature without use of a secondary locking feature and/or step to prevent a size of the loop from increasing.

In some implementations, the clamping assembly may comprise an inner coupling piece and an outer coupling piece configured to receive the inner coupling piece. In some such implementations, one or both of the first passage and the second passage may be at least partially defined by an inner surface of the outer coupling piece and an outer surface of the inner coupling piece.

In some implementations in which the elongate member comprises a rod, the inner coupling piece may comprise a slot configured to receive and engage the rod. Thus, in some such implementations, the step of coupling the elongate member with the clamping assembly may comprise engaging the rod with the slot.

Non-limiting and non-exhaustive embodiments of the disclosure are described, including various embodiments of the disclosure with reference to the figures, in which:.

A detailed description of assemblies consistent with various embodiments of the present disclosure is provided below.

Assemblies are disclosed herein relating to spinal fixation or other bone fixation. In some embodiments, tether clamping assemblies may be provided, such as clamping assemblies used to clamp a tether about a spinal feature to assist in spinal fixation. More particularly, in some embodiments, a tether clamping assembly may also be configured to engage a spinal fixation rod. In preferred embodiments, the clamping assembly may be configured such that one or more portions of a tether may be self-locked therein without requiring any additional locking elements, features, or steps. In this manner, for example, a tether may be looped around a spinal feature or other anatomical feature, coupled with a fixation element, such as a rod, and then locked in place to stabilize the anatomical feature.

The embodiments of the disclosure may be best understood by reference to the drawings, wherein like parts may be designated by like numerals. It will be readily understood that the components of the disclosed embodiments, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the apparatus and methods (the methods not claimed) of the disclosure is not intended to limit the scope of the disclosure, as claimed, but is merely representative of possible embodiments of the disclosure. In addition, the steps of a method do not necessarily need to be executed in any specific order, or even sequentially, nor need the steps be executed only once, unless otherwise specified. Additional details regarding certain preferred embodiments and implementations will now be described in greater detail with reference to the accompanying drawings.

<FIG> is an exploded view of a spinal fixation assembly <NUM> according to some embodiments. Assembly <NUM> comprises a tether <NUM> that is configured to engage a spinal feature of a patient's spine, such as looped around the spinal lamina and/or other spinal features, such as the transverse processes of the patient's spine. Tether <NUM> in some embodiments, may comprise a flat, flexible band resembling, for example, a piece of tape. In preferred embodiments, tether <NUM> may be flat and/or smooth on both opposing sides. According to the invention, tether <NUM> is devoid of locking teeth and/or other projections.

Assembly <NUM> further comprises a tether clamping assembly <NUM> configured to engage and couple a coupling member, such as a rod <NUM> or other elongate member, with the tether <NUM> so as to facilitate coupling of a patient's spine in a desired position without use of pedicle screws or other similar bone-invasive components. Assembly <NUM> further comprises a cap <NUM> configured to engage tether clamping assembly <NUM>, as described in greater detail below. Although preferred embodiments disclosed herein, including assembly <NUM>, may be configured to allow for coupling of a tether with spinal features, it is contemplated that the inventive principles disclosed herein may be applied to provide for clamping/securing of a tether to other anatomical features, such as securing two portions of a broken or cracked bone, such as a femur, for example. In some such embodiments not involving spinal anatomy, the spinal rod or other fixation member discussed below may be omitted. The bone itself may be clamped by the clamping assembly <NUM> instead of clamping both the tether and the rod/fixation member.

<FIG> is a side elevation view of spinal fixation assembly <NUM>. As shown in this figure, tether clamping assembly <NUM> comprises two separate pieces, namely, a first or inner coupling piece <NUM> and a second or outer coupling piece <NUM> configured to be coupled with the first coupling piece <NUM>.

First/inner coupling piece <NUM> defines a slot <NUM> for receipt of a rod <NUM> or other elongate and/or rigid coupling member therethrough. Preferably, slot <NUM> is shaped to match, or at least substantially match, the shape of the outer surface of rod <NUM> such that rod <NUM> may be firmed engaged/gripped by slot <NUM>. In some embodiments, slot <NUM> may comprise a plurality of engagement features <NUM>, such as teeth, grooves, spikes, or a contoured and/or roughened surface to further facilitate a firm engagement between rod <NUM> and inner coupling piece <NUM>. This roughening may be applied, in some embodiments, by way of diamond plating, blasting, etc. In some embodiments, one or both of the coupling pieces may comprise features that allow for slot <NUM> to resiliently flex to receive rod <NUM> therein and then snap back in place to fixedly engage rod <NUM>, as discussed in greater detail below.

In embodiments providing a snap-on feature, slot <NUM> may also be roughened, textured, and or provided with teeth or other engagement features <NUM>, as mentioned above. In this manner, the inner coupling piece <NUM> may be snapped onto the rod <NUM> and the inner coupling piece <NUM> may be held in place on the rod without requiring a practitioner to hold it in place by virtue of the engagement features <NUM> and/or a textured or roughened surface. However, in order to allow the inner coupling piece <NUM> to be slid to its desired location on the rod <NUM>, it may be preferred that the frictional engagement be configured so as to allow a practitioner to manually overcome the friction to move the inner coupling piece <NUM> and/or assembly <NUM> as needed during surgery.

<FIG> is a cross-sectional view of spinal fixation assembly <NUM>. As depicted in this figure, first/inner coupling piece <NUM> is configured to be received within second/outer coupling piece <NUM> in a nesting fashion. In some embodiments, including the depicted embodiment, first/inner coupling piece <NUM> is configured to be wholly received within second/outer coupling piece <NUM>. However, it is contemplated that, in other embodiments, a portion of the outer coupling piece may protrude from the inner coupling piece or, as discussed in connection with another embodiment below, tether clamping assembly <NUM> may instead comprise a single element.

Second/outer coupling piece <NUM> may similarly comprise a slot <NUM> that may be configured to be aligned with slot <NUM> upon coupling inner coupling piece <NUM> with outer coupling piece <NUM>. By coupling inner coupling piece <NUM> with outer coupling piece <NUM>, a pair of opposing passages are defined for receipt of separate portions of tether <NUM> therethrough.

Thus, first and second passages may be defined, respectively, by an inner surface <NUM> of outer coupling piece <NUM> and an outer surface <NUM> of inner coupling piece <NUM>, both of which may be configured to receive separate portions of tether <NUM> therethrough. In preferred embodiments, clamping assembly <NUM> is self-locking. In other words, by advancing tether <NUM> through one or both passages, the tension on tether <NUM> alone results in a tightening, and preferably a locking, of tether <NUM> in clamping assembly <NUM>.

According to the invention, clamping assembly <NUM> is configured such that tether <NUM> can be clamped and/or locked in clamping assembly <NUM> so as to allow tether <NUM> to move through one or both passages in a first direction to lock the tether in place but so as to prevent, or at least substantially prevent, tether <NUM> from moving through one or both passages in a second direction opposite from the first direction. Thus, with respect to the view of <FIG> and <FIG>, tether <NUM> may be advanced in an upward direction along both opposing passages, thereby resulting in a tether loop (see <FIG>) that gets smaller, but may be prevented, or at least substantially prevented, from being advanced in a downward direction. Thus, upon applying a force to tether <NUM> in the upward direction, the loop locks in place, preferably about a spinal feature. In some embodiments, the greater the force applied in a locking direction, the tighter the lock, and therefore the more difficult it is to move the tether in an opposite direction from the locking direction.

In the depicted embodiment, this self-locking feature may be enhanced by providing a friction differential between the two opposing surfaces through which one or more portions of tether <NUM> are received. Preferably, this friction differential is applied such that a movable surface has a greater surface roughness than an opposing non-movable surface. Because, as discussed in greater detail below, in some implementations of methods disclosed herein, the inner coupling piece <NUM> may be coupled with a rod <NUM> or other elongate member prior to coupling outer coupling piece <NUM> with inner coupling piece <NUM>, outer coupling piece <NUM> may be considered the "moveable" element of clamping assembly <NUM>.

Thus, for example, as depicted in <FIG>, inner surface(s) <NUM> of outer coupling piece <NUM> comprises a plurality of projections <NUM>. In some embodiments, projections <NUM> may be defined by a plurality of elongated grooves formed on the inner surface <NUM> of outer coupling piece <NUM>. However, alternative embodiments are contemplated in which projections <NUM> may comprise, for example, teeth. As still another alternative, inner surface <NUM> of outer coupling piece <NUM> may, in some embodiments, lack deliberately formed projections and may instead simply comprise a roughened surface. Outer surface(s) <NUM> of inner coupling piece <NUM> may, in some embodiments, comprise a smooth surface. However, so long as a friction differential is provided, whether by providing projections <NUM> or otherwise, outer surface(s) <NUM> need not be smooth in some embodiments. Surfaces <NUM> and <NUM>, along with their respective surface features, are therefore an example of means for self-locking a tether within a rod-coupling assembly.

It is also contemplated, however, that, in some embodiments, suitable locking may be provided without providing the friction differential described above. For example, the embodiment depicted in <FIG> also provides for self-locking of tether <NUM> by virtue of a wedge-locking feature. Thus, although it may be preferred to have the two opposing surfaces <NUM>/<NUM> have a friction differential, this may be omitted in certain contemplated embodiments. In embodiments in which these two surfaces are identical, or at least substantially identical, it is also preferred that both surfaces be roughened, contoured, and/or formed with frictional features, such as teeth or protrusions, for example. However, it is also contemplated that for certain applications opposing surfaces <NUM>/<NUM> may instead both be smooth.

Because of the unique design of assembly <NUM>, locking of tether <NUM> may also result in further locking/tightening of the grip on rod <NUM>. For example, due to the wedging of outer coupling piece <NUM> onto inner coupling piece <NUM>, as the tension on tether <NUM> is increased in the tightening direction by pulling one or both ends of tether <NUM> through the two opposing passages defined by outer coupling piece <NUM> and inner coupling piece <NUM>, not only is tether <NUM> pinched more tightly therebetween to prevent it from being loosened, but, at the same time, the slot <NUM> created by the inner surface of inner coupling piece <NUM> is squeezed against the rod <NUM> more tightly to further lock the tether clamping assembly <NUM> in place with respect to the rod <NUM>. This feature is provided for by virtue of the wedge lock previously described, in which two tapering surfaces are wedged against each other (with the tether <NUM> therebetween) in combination with making the inner coupling piece <NUM> flexible so that the size of slot <NUM> can vary to facilitate this compression. Preferably, as shown in the depicted embodiment, these tapering surfaces are frusto-conical surfaces.

Other features of spinal fixation assembly <NUM> can be seen in <FIG>. For example, as shown in <FIG>, inner coupling piece <NUM> may comprise a central opening <NUM>, which may be threaded to receive cap <NUM>. Opening <NUM> may be configured to be aligned with opening <NUM> of outer coupling piece <NUM>, as shown in <FIG>, upon coupling of outer coupling piece <NUM> with inner coupling piece <NUM>. Although preferably openings <NUM> and <NUM> are configured to be aligned when outer coupling piece <NUM> is coupled with inner coupling piece <NUM>, opening <NUM> need not be threaded since threaded opening <NUM> may engage cap <NUM> and thereby engage outer coupling piece <NUM> without itself requiring a direct threaded connection with cap <NUM>.

Inner coupling piece <NUM> may further comprise opposing grooves <NUM>. Grooves <NUM> may be provided in order to increase the flexibility of slot <NUM>. For example, as previously mentioned, slot <NUM> may be configured to expand to receive rod <NUM> and then resiliently snap back in place to at least partially envelop rod <NUM>, which functionality may be provided by grooves <NUM>. In some embodiments, grooves <NUM> may also, or alternatively, be used to provide locations to facilitate gripping/engagement by an instrument that may be used to install coupling piece <NUM> and/or hold coupling piece <NUM> in place during one or more stages of a surgical procedure.

As also better seen in <FIG>, inner coupling piece <NUM> may comprise opposing outer surfaces 142A and 142B, each of which may partially define a separate tether passage. As previously mentioned, preferably, outer surfaces 142A and 142B are smooth or at least have surface roughnesses that are less than that of respective opposing surfaces, which may be defined by outer coupling piece <NUM>, that, together with outer surfaces 142A and 142B, define opposing tether passages. Similarly, <FIG> better depicts opposing grooves 144A and 144B, which directly extend from opposing outer surfaces 142A and 142B, respectively. As best shown in this figure, grooves 144A and 144B, together with slot <NUM>, form opposing narrowed portions that provide the aforementioned flexibility and/or provide engagement locations for a suitable instrument.

<FIG> is a perspective view of outer coupling piece <NUM>. As best seen in this figure, the upper portion of outer coupling piece <NUM> may comprise one or more features to facilitate desired functionality. For example, as previously mentioned an opening <NUM> may be provided to receive a threaded projection or another projection from a cap and/or set screw. In addition, opening <NUM> need not be threaded, but may be defined by a plate <NUM> configured to engage a portion of inner coupling piece <NUM> that defines a threaded opening <NUM> configured to be aligned with opening <NUM> such that inner coupling piece <NUM> can extend into but cannot extend out of the opposite end of outer coupling piece <NUM>. Plate <NUM> may also be configured to provide a surface upon which a flanged portion <NUM> of cap <NUM> may rest and/or pinch a portion of tether <NUM>, as discussed in greater detail below.

Plate <NUM> may further define opposing tether openings 156A and 156B. In embodiments using a tether having an elongated, rectangular cross-section, such as tether <NUM>, tether openings 156A and 156B may have a similar matching shape such that the tether may snap into place when properly oriented within the opposing passages, the openings at one end of which are defined by tether openings 156A and 156B.

Tether openings 156A and 156B may be partially defined by four corners <NUM> that are positioned along the portion of outer coupling piece <NUM> defining opening <NUM>. Corners <NUM> are defined by opening <NUM> along with respective walls that extend parallel to slit <NUM> (and therefore extend parallel to an axis defined by a rod positioned therein). These tether openings 156A/156B may be useful in allowing the tether to be held in place temporarily (before locking/clamping) to allow a practitioner to perform other tasks while awaiting finalization of the installation/surgery.

As also shown in <FIG>, opposing slits 159A and 159B may be formed adjacent to plate <NUM>. As best seen in <FIG>, which depicts assembly <NUM> with cap <NUM> in place, slits 159A and 159B may, together with flanged portion <NUM> of cap <NUM>, define opposing apertures through which opposing portions of tether <NUM> may exit from opposing sides of assembly <NUM>.

Some embodiments may further comprise one or more features to facilitate engagement with a suitable instrument. Thus, for example, outer coupling piece <NUM> comprises a notch <NUM>, which may engage a corresponding protruding element of a suitable surgical instrument. Although not visible in <FIG>, in some embodiments, a similar notch may be formed on the opposite side of outer coupling piece <NUM>.

<FIG> more clearly depicts projections <NUM> formed within curved inner surface 152A of outer coupling piece <NUM>. As shown in this figure, projections <NUM> may be formed by cutting elongated, parallel grooves within inner surface 152A. Although not visible in <FIG>, as previously mentioned, in preferred embodiments, the opposing inner surface similarly comprises a plurality of projections <NUM> to facilitate the self-locking feature of assembly <NUM>.

<FIG> is a perspective view of a cap <NUM> of spinal fixation assembly <NUM> according to some embodiments. Cap <NUM> comprises a flanged portion <NUM>, which may be configured to engage an upper surface of outer coupling piece <NUM>, such as plate <NUM>. Cap <NUM> further comprises a male threaded portion <NUM> and a keyed slot <NUM>. As previously mentioned, male threaded portion <NUM> may be configured to engage female threads of inner coupling piece <NUM> and outer coupling piece <NUM> may be clamped therebetween. Keyed slot <NUM> may be configured to engage an instrument, such as a driver, used to couple cap <NUM> to assembly <NUM>.

In some embodiments, a portion or, in some such embodiments, two opposing portions, of the tether <NUM> may be clamped in between flanged portion <NUM> of cap <NUM> and another portion of assembly <NUM>, such as the ledges formed by opposing slits 159A and 159B or plate <NUM> of outer coupling piece <NUM>. Thus, cap <NUM> is an example of secondary means for locking a tether within a rod-coupling assembly. Cap <NUM> may also serve the function of increasing the lock on the rod and/or tether and/or decreasing the possibility of unwanted loosening/disassembly.

In addition, providing cap <NUM> may decrease the possibility of frayed portions of tether <NUM> from extending down into assembly <NUM> following cutting of tether <NUM>. This may allow for cutting of tether <NUM> closer to assembly <NUM> than may otherwise be possible or desirable. However, as previously explained, self-locking may be provided by the differential friction of the opposing surfaces of one or both tether passages of tether clamping assembly <NUM>. Thus, it is contemplated that cap <NUM> may be omitted in some embodiments. It is also contemplated that cap <NUM> may comprise a set screw lacking a flanged portion in some embodiments.

<FIG> is a perspective view of tether clamping assembly <NUM> showing inner coupling piece <NUM> fully inserted within outer coupling piece <NUM> and with cap <NUM> fully engaged with inner coupling piece <NUM>. Although normally a tether would be engaged between opposing surfaces of inner coupling piece <NUM> and outer coupling piece <NUM>, respectively, in this configuration, tether <NUM> is omitted from <FIG> to allow for better viewing of certain features of assembly <NUM>. Most notably, opposing apertures are depicted that may allow for a tether to exit from opposite sides of assembly <NUM>. These apertures are defined by opposing slits <NUM> (only one of which is visible in <FIG>), respectively, along with a lower surface of flanged portion <NUM> of cap <NUM>.

Another unique feature of assemblies <NUM> and/or <NUM> is the ability to loosen the grip/lock/clamp on the tether <NUM> for readjustment. As previously mentioned, locking of the tether may be accomplished automatically by engaging the tether <NUM> between the opposing surfaces of the inner and outer coupling pieces and pulling the tether through one or both of the openings in the locking direction, with the optional cap <NUM> to further enhance this locking of the tether <NUM> and/or the rod <NUM>. This may allow for sequential tightening of various elements of a spinal fixation system without leaving instrumentation in place while moving to a new location within the system, which may also reduce the instrument tray and decrease surgery time.

However, if loosening is needed, the outer coupling piece <NUM> may be engaged, likely with a suitable instrument, in order to lift the outer coupling piece <NUM> away from the inner coupling piece <NUM> slightly, which will release the lock on tether <NUM> and allow the tether <NUM> to be loosened. In some embodiments, notch <NUM> may be configured to engage a corresponding element of a suitable surgical instrument in order to facilitate this loosening.

<FIG> is a perspective view of an alternative embodiment of a spinal fixation assembly <NUM>. Although not depicted in <FIG>, assembly <NUM> would typically comprise a tether, which may be similar to tether <NUM>, that is configured to engage a spinal feature of a patient's spine, such as, in preferred embodiments, looped around the spinal lamina and/or other spinal features, such as the transverse processes of the patient's spine.

Like assembly <NUM>, assembly <NUM> further comprises a tether clamping assembly <NUM> configured to engage and couple a coupling member, such as a rod <NUM> or other elongate member, with a tether so as to facilitate coupling of a patient's spine in a desired position without use of pedicle screws or other similar bone-invasive components. Tether clamping assembly <NUM> again comprises two separate elements configured to be coupled with one another so as to clamp one or more (preferably two) portions of a tether therein. More particularly, tether clamping assembly <NUM> comprises an inner coupling piece <NUM> configured to be received within an outer coupling piece <NUM>.

However, tether clamping assembly <NUM> differs from tether clamping assembly <NUM> in several ways. For example, as shown in <FIG> and <FIG>, inner coupling piece <NUM> comprises a pair of removable tabs, namely, tabs 970A and 970B. Tabs 970A and 970B may be configured to facilitate coupling of outer coupling piece <NUM> with inner coupling piece <NUM>. Tabs 970A and 970B may comprise a plurality of ridges <NUM>.

Each ridge <NUM>, or each pair of adjacent ridges <NUM>, may serve a distinct purpose during the installation process. For example, the top pair of ridges <NUM> may be used to prevent the outer coupling piece <NUM> from being removed from assembly <NUM> during, for example, snapping of the rod <NUM> into slot <NUM>. The middle pair of ridges <NUM> may prevent the outer coupling piece <NUM> from dropping all of the way down adjacent to the threaded opening <NUM> of inner coupling piece <NUM> to provide spacing for an instrument or a surgeon's hand during this stage.

Following this stage, the outer coupling piece <NUM> may be dropped down below the lowest pair of ridges to allow for threading of the tether through opposing passages defined by respective inner surfaces of the outer coupling piece <NUM> and respective, opposing outer surfaces of the inner coupling piece <NUM>, as previously described. After threading the tether through these passages, the tether may be tensioned about a spinal feature and/or bone.

As previously mentioned, preferably tether clamping assembly <NUM> is configured to provide for self-locking of the tether. In other words, in some embodiments, the tether clamping assembly <NUM> may be configured such that the tether can be clamped in between opposing surfaces so as to allow the tether to move through the passage(s) in a first direction and lock the tether in place so as to, without any further steps or locking elements/features, at least substantially prevent the tether from moving through the passage(s) in a second direction opposite from the first direction. As also previously mentioned, this self-locking feature may be provided by providing a friction differential between the two opposing surfaces through which one or more portions of the tether are received. Preferably, this friction differential is applied such that a movable surface has a greater surface roughness than an opposing non-movable surface.

Thus, for example, as depicted in <FIG> and <FIG>, opposing inner surface(s) <NUM> of outer coupling piece <NUM> comprises a plurality of projections <NUM>, which may be formed by elongated grooves. Outer surface(s) <NUM> of inner coupling piece <NUM> may, in some embodiments, comprise a smooth surface, or at least a surface lacking projections/grooves. However, again, so long as a friction differential is provided, whether by providing projections <NUM> or otherwise, outer surface(s) <NUM> need not necessarily be smooth. Surfaces <NUM> and <NUM>, along with their respective surface features, are therefore another example of means for self-locking a tether within a rod-coupling assembly.

Once the tether has been suitably tensioned and locked in place, tabs 970A and 970B may be removed. In order to facilitate such removal, weakened portions <NUM>, such as frangible weakening lines, may be formed in one or both of tabs 970A and 970B. Inner coupling piece <NUM> may also comprise opposing grooves <NUM> for increasing the flexibility of slot <NUM> and/or facilitate gripping/engagement by a surgical instrument.

Like outer coupling piece <NUM>, outer coupling piece <NUM> comprises an opening <NUM>, which may be configured to receive a threaded projection or another projection from a cap and/or set screw. Opening <NUM> need not be threaded but may be configured to be aligned with a threaded opening <NUM> of inner coupling piece <NUM>, as previously described. Outer coupling piece <NUM> may further comprise one or more notches <NUM>, which may engage a corresponding protruding element of a suitable surgical instrument.

However, outer coupling piece <NUM> differs from outer coupling piece <NUM> in several respects. For example, opposing apertures <NUM> are formed in outer coupling piece (only one of which is visible in <FIG>) such that a tether (not shown) may extend through the opposing passages previously mentioned and, instead of exiting from an upper surface, may extend through opposing apertures <NUM> formed in side walls of outer coupling piece <NUM>.

In addition, instead of comprising opposing slits 159A and 159B in a top surface of the outer coupling piece, as is the case in outer coupling piece <NUM>, outer coupling piece <NUM> comprises opposing slits 959A and 959B formed in an inner surface of outer coupling piece <NUM>. Opposing slits 959A and 959B may be configured to partially accommodate ridges <NUM>. However, in order to secure outer coupling piece <NUM> in a desired position on tabs 970A/970B, preferably slits 959A/959B are slightly smaller than ridges <NUM> such that ridges <NUM> prevent passage of outer coupling piece <NUM>. Passage of outer coupling piece <NUM> beyond a given set of ridges <NUM> may be accomplished by, for example, flexing tabs 970A/970B.

<FIG> depicts yet another alternative embodiment of a spinal fixation assembly <NUM>. Although not depicted in <FIG>, assembly <NUM> would typically comprise a tether, which may be similar to tether <NUM>, that is configured to engage a spinal feature of a patient's spine, and an elongated fixation member or other coupling member, such as a rod.

Like assemblies <NUM> and <NUM>, assembly <NUM> comprises a tether clamping assembly <NUM> comprising two separate elements configured to be coupled with one another so as to clamp one or more (preferably two) portions of a tether and rod or other coupling member therein. More particularly, tether clamping assembly <NUM> comprises an inner coupling piece <NUM> configured to be received within an outer coupling piece <NUM>, as previously described.

However, tether clamping assembly <NUM> differs from the tether clamping assemblies previously described in several ways. For example, as shown in <FIG> and <FIG>, tether clamping assembly <NUM> comprises an alignment insert <NUM> that is configured to be received within an opening formed within outer coupling piece <NUM> and/or inner coupling piece <NUM>. Alignment insert <NUM> may be used to facilitate coupling of outer coupling piece <NUM> with inner coupling piece <NUM> and/or may be used to facilitate introduction of a set screw (not shown) into inner coupling piece <NUM>. Thus, alignment insert <NUM> may comprise a tip <NUM>, which may be configured with a smaller diameter relative to an adjacent body portion <NUM> so as to allow for receipt of tip <NUM> within one or both of threaded opening <NUM> of inner coupling piece <NUM> (see <FIG>) and opening <NUM> of outer coupling piece <NUM> (see <FIG>). Opposite from tip <NUM> is a handle <NUM>, which may be configured to allow a surgeon or practitioner to push alignment insert <NUM> into one or more receiving openings to facilitate introduction and coupling of a set screw into threaded opening <NUM>. A central bore <NUM> may be formed in alignment insert <NUM> and may extend from handle <NUM> to tip <NUM> to allow for a set screw to travel therethrough. A suitable instrument may also be received within bore <NUM> to further facilitate such coupling.

A perspective view of the inner coupling piece <NUM> is shown in <FIG>. As shown in this figure, inner coupling piece <NUM> comprises a pair of opposing outer surfaces, namely surfaces 1242A and 1242B. As previously discussed, surfaces 1242A and 1242B, respectively, may be configured to define one side of a passage for receipt of a tether (not shown) therethrough. As also previously discussed, surfaces 1242A and 1242B are preferably smooth, or at least having a surface roughness that is less than that of the opposing surface(s), which may be defined by an inner surface or surfaces of outer coupling piece <NUM>.

As also previously discussed, inner coupling piece <NUM> may comprise a slot <NUM> that is shaped to match, or at least substantially match, the shape of the outer surface of a rod such that the rod may be firmly engaged/gripped by slot <NUM>. In some embodiments, slot <NUM> may comprise a plurality of teeth (not shown) or a contoured and/or roughened surface to further facilitate a firm engagement between the rod and inner coupling piece <NUM>. Inner coupling piece <NUM> further comprises a pair of opposing grooves, namely, grooves 1244A and 1244B, which may increase the flexibility of slot <NUM> to allow for receipt of a rod therein by way of a snap-fit connection. In the depicted embodiment, grooves 1244A and 1244B comprise slits that terminate adjacent to slot <NUM>.

A perspective view of outer coupling piece <NUM> is shown in <FIG>. As shown in this figure, outer coupling piece <NUM>, like inner coupling piece <NUM>, may comprise a slot <NUM> that may be aligned with slot <NUM> such that a rod (not shown) or another coupling member may extend through a slot defined by slots <NUM> and <NUM>.

As also shown in <FIG>, opposing apertures 1256A and 1256B are formed in outer coupling piece <NUM> such that a tether (not shown) may extend through the opposing passages previously mentioned and ultimately extend through opposing apertures 1256A and 1256B. Apertures 1256A and 1256B are formed in opposing shelves 1259A and 1259B of outer coupling piece <NUM>. Shelves 1259A and 1259B may be configured to be aligned, or at least substantially aligned, with the top surface of inner coupling piece <NUM> upon fully coupling outer coupling piece <NUM> with inner coupling piece <NUM>.

Finally, as previously discussed, outer coupling piece <NUM> further comprises two internal surfaces each having a plurality of projections <NUM>, which may, in some embodiments, be defined by a series of parallel grooves, as previously described. These surfaces, together with outer surfaces 1242A and 1242B of inner coupling piece <NUM>, define two separate passages for receipt of opposing portions of a tether therethrough, as also previously described. The opposing surfaces that define these two passages, along with their respective surface features, are therefore another example of means for self-locking a tether within a rod-coupling assembly.

<FIG> depict still another embodiment of a tether clamping assembly <NUM> that may be used in connection with a fixation assembly, such as a spinal fixation assembly. Tether clamping assembly <NUM> is configured to receive two portions of a tether (not shown) therethrough so as to define a loop and tighten the loop around a spinal feature or other anatomical feature, as previously discussed. However, tether clamping assembly <NUM> differs from the other coupling assemblies described herein in that tether clamping assembly <NUM> is defined by a unitary structure rather than two separate structures coupled together. More particularly, tether clamping assembly <NUM> comprises an internal structure defined by two locking members 1651A and 1651B.

Locking members 1651A and 1651B are movably (in the depicted embodiment, pivotably) positioned in respective internal chambers so as to define empty spaces on either side. More particularly, locking members 1651A and 1651B are positioned in between respective inner spaces 1657A/1657B and outer spaces 1659A/1659B. In the depicted embodiment, opposing tether receiving paths are defined by outer spaces 1659A/1659B, as best seen in the cross-sectional view of <FIG>.

Respective outer surfaces of locking members 1651A and 1651B may comprise a plurality of projections <NUM>, or may otherwise be surface roughened relative to the opposing inner surfaces 1642A and 1642B. Thus, both passages of coupling mechanism <NUM> are configured to be self-locking with respect to tether portions received therethrough. In order words, upon extending respective tether portions through these passages and applying tension in the upward direction (relative to the orientation in <FIG> and <FIG>), the tether portions retain the applied tension and are prevented, or at least inhibited, from being pulled in the opposite, downward direction. The opposing surfaces defining passages 1659A and 1659B, along with their respective surface features, are therefore another example of means for self-locking a tether within a rod-coupling assembly.

Surface 1642A, together with the surface upon which projections 1653A are formed, define a first passage 1659A for receiving a first portion of a tether, such as a flexible band, therethrough. Similarly, surface 1642B, together with the surface upon which projections 1653B are formed, define a second passage 1659B for receiving a second portion of the tether therethrough. These passages have openings on opposite ends of tether clamping assembly <NUM>, namely, upper openings 1656A and 1656B and respective lower openings 1652A and 1652B.

Preferably, locking members 1651A and 1651B are pivotably movable within their respective chambers. Thus, outer spaces 1659A/1659B may be configured, respectively, to allow locking members 1651A and 1651B to be resiliently biased towards the center of tether clamping assembly <NUM> by a predetermined distance. Correspondingly, the width of the opposing passages defined in part by locking members 1651A and 1651B may be slightly increased as locking members 1651A and 1651B pivot in this manner. In addition, as depicted in the figures, respective base portions of locking members 1651A and 1651B may be narrowed to provide the flexibility to allow for this pivoting/movement.

Because locking members 1651A and 1651B are movable, as previously discussed, preferably the friction differential between the opposing surfaces defining the passages are applied such that the surface on locking members 1651A and 1651B (the movable surfaces) have a greater surface roughness than the opposing non-movable surfaces. Thus, as previously mentioned, the projections <NUM> may only be formed on these surfaces of locking members 1651A and 1651B and not on the opposing inner surfaces 1642A and 1642B of the inner chamber of tether clamping assembly <NUM>.

Tether clamping assembly <NUM> further comprises release mechanisms to allow the self-locking feature to be unlocked. In the depicted embodiment, these release mechanisms comprise tether clamping assembly openings 1658A and 1658B which are positioned to allow access to respective locking member openings 1654A and 1654B formed in upper surfaces of locking members 1651A and 1651B. As best shown in the cross-sectional view of <FIG>, openings 1654A and 1654B may be configured to receive portions of a suitable instrument, such as prongs. In some embodiments, this may allow a user to, for example, squeeze the locking members 1651A and 1651B towards one another and thereby release their respective locks on the tether portions extending through the tether passages extending between upper openings 1656A and 1656B and respective lower openings 1652A and 1652B. Of course, only one of the locking member openings 1654A and 1654B may be engaged, if desired, in order to only unlock the locking/clamping of tether clamping assembly <NUM> on one tether portion instead of both portions extending through tether clamping assembly <NUM>.

Various methods for clamping a tether to a spinal feature or other anatomical feature may also be performed using one or more of the inventive clamping assemblies, or sub-elements of such an assembly, taught herein. For example, in some implementations of such methods, a tether, such as in some such implementations a flexible band, may be extended in a loop around an anatomical feature, such as around a spinal transverse process or spinal lamina, for example. An elongate member, such as a rigid rod, may be coupled with a clamping assembly, such as any of the various clamping assemblies disclosed herein.

A first end of the tether may then be fed through a first passage of the clamping assembly. In some implementations, the first passage may be defined by a first pair of opposing surfaces having distinct surface roughnesses. In some such implementations, a movable surface (relative to the elongate member) may comprise a greater surface roughness that an opposing non-movable surface. Thus, for example, the movable surface may be formed with a plurality of grooves and/or projections to increase the surface roughness and/or grip on the tether.

In some implementations, a second end of the flexible tether opposite from the first end may also be fed through a second passage, which may be defined by a second pair of opposing surfaces also having distinct surface roughnesses. In some implementations, the first end of the flexible tether may be fed through the first passage and/or the second end of the flexible tether may be fed through the second passage to automatically lock the flexible tether in place about the anatomical feature without the use of a secondary locking feature, such as a locking cap, set screw, or the like, to prevent a size of the loop from increasing.

In some implementations, the clamping assembly may comprise an inner coupling piece and an outer coupling piece configured to receive the inner coupling piece. In some such implementations, the first passage and the second passage may be at least partially defined by an inner surface of the outer coupling piece and an outer surface of the inner coupling piece.

In some implementations, the clamping assembly may also be unlocked following the self-locking procedure. For example, a user may unlock one or both tether portions using a means for unlocking a self-locking tether, such as the locking member openings 1654A and 1654B formed in upper surfaces of locking members 1651A and 1651B, for example. This may allow for readjustment or loosening of a tether clamping assembly following self-locking of the tether within the assembly.

Claim 1:
A spinal fixation assembly (<NUM>), comprising:
a tether (<NUM>) configured to engage a spinal feature of a patient's spine, wherein the tether (<NUM>) is devoid of locking teeth;
an inner coupling piece (<NUM>), wherein the inner coupling piece (<NUM>) comprises a slot (<NUM>) configured to receive and engage a rod (<NUM>) therein;
an outer coupling piece (<NUM>) configured to be coupled with the inner coupling piece (<NUM>) in a nesting fashion;
a first passage configured to receive a first portion of the tether (<NUM>), wherein the first passage is defined by an inner surface (<NUM>) of the outer coupling piece (<NUM>) and an outer surface (<NUM>) of the inner coupling piece (<NUM>), wherein the first passage is configured such that the tether (<NUM>) can be clamped in between the inner surface (<NUM>) and the outer surface (<NUM>) so as to allow the tether (<NUM>) to move through the first passage in a first direction and lock the tether (<NUM>) in place so as to at least prevent the tether (<NUM>) from moving through the first passage in a second direction opposite from the first direction.