Patent Description:
As can be appreciated, the open procedure described above results in a relatively significant amount of trauma to the patient as a significant amount of tissue and muscle must be cut and retracted to allow access to the surgical site. Minimally invasive tools and procedures have been developed to reduce the amount of trauma as well as reduce the recovery time. One such minimally invasive system includes the ' <NUM><NUM> Patent disclosed above. The <NUM> Patent allows for a smaller or minimal incision by providing a surgical corridor formed by inner and outer sleeves that locked to a pedicle screw or a pedicle screw tulip. A surgeon accesses the surgical site through the surgical corridor formed by the sleeves.

Another minimally invasive tool is disclosed by <CIT>. The ' <NUM> Patent similarly describes a tool that forms a corridor and connects to a bone anchor. The ' <NUM> Patent has a proximal end extending from the patient. The inner sleeve of the instrument is movable relatively to the outer sleeve, via a plunger or the like, that resides along the center line of the corridor formed by the tool. The instrument <NUM> disclosed by the '<NUM> Patent provides for a minimally invasive mechanism to manipulate the vertebrae and to seat the rods 90A, 90B into the bone anchors, but does not provide a convenient mechanism to move the rods 90A, 90B from outside the patient to inside the patient.

Other similarly minimally invasive tools provide a special rod introduction tool. For example, <CIT>, titled PEDICLE SCREW EXTENSION FOR USE IN PERCUTANEOUS SPINAL FUSION provides for a rod introducer that slidingly engages the outside of a pedicle screw extension and moves a rod into position as the tool slides from a proximal to a distal location along the extension. The tool of the <NUM> application, as well as other similar pedicle screw extenders as they are generally known in the art, leaves much to be desired. In particular, rod introducers for the current extenders are customer tools that are adapted to engage the outside of the extender, rather than using the hollow center of the extenders. The rod introducer is offset from the pedicle screw extender requiring a slightly larger incision. Also, the pedicle screw extenders themselves, as presently constructed, provide an obstructed view of the surgical area. <CIT> discloses a minimally invasive tool to facilitate implanting a pedicle screw and housing.

Thus, against the above background, an improved pedicle screw extender would be desirable.

Accordingly the invention provides a system for facilitating minimally invasive surgical procedures as defined in claim <NUM>.

Various examples of the technology of the present application will be discussed with reference to the appended drawings. These drawings depict only illustrative examples of the technology described more fully herein and are not to be considered limiting of its scope.

The technology of the present application will be described in the context of spinal surgery, but one of ordinary skill in the art will recognize on reading the disclosure that the technology may be applicable to other medical fields. Moreover, the technology of the present application will be described with reference to certain exemplary embodiments. " Any embodiment described herein whether or not specifically identified as "exemplary" is not to be construed as preferred or advantageous over other embodiments. Moreover, in certain instances only a single "exemplary" embodiment is provided. A single example is not necessarily to be construed as the only embodiment. It also should be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in this specification, the singular forms "a," "an," and "the" include plural references unless the context of the disclosure clearly dictates otherwise. Thus, for example, reference to "a lithium hydroxide" is not to be taken as quantitatively or source limiting, reference to "a step" may include multiple steps, reference to "producing" or "products" of a reaction should not be taken to be all of the products of a reaction, and reference to "reacting" may include reference to one or more of such reaction steps. As such, the step of reacting can include multiple or repeated reaction of similar materials to produce identified reaction product.

Further, the instrument(s) described in accordance with the technology of the present application facilitate surgical implantation of pedicles screws and fixation rods for spinal fusion. With that in mind, exemplary spinal fixation systems may include polyaxial or monoaxial pedicle screws as are generally understood in the art. Moreover, the instruments may be useful for surgery relating to fixation of the cervical, thoracic, and/or lumbar spine. Additionally, the instruments may be useful in other orthopedic fusion procedures where two or more boney segments are to be fused using rods and screws to immobilize the segments.

The detailed description includes specific details for the purpose of providing a thorough understanding of the technology of the present patent application. However, on reading the disclosure, it will be apparent to those skilled in the art that the technology of the present patent application may be practiced with or without these specific details. In some descriptions herein, generally understood structures and devices may be shown in block diagrams to aid in understanding the technology of the present patent application without obscuring the technology herein.

Referring first to <FIG> and <FIG>, a tool <NUM> coupled to a saddle <NUM> is provided. The saddle <NUM> is a portion of an implant usable in pedicle screw and rod fixation systems as is generally known in the art. It should be noted that saddle <NUM> may be a number of different implants, however. The tool <NUM> has a proximal end <NUM> and a distal end <NUM>. The tool <NUM> has a longitudinal axis <NUM> extending between first and second outer blades or elongate members <NUM>, <NUM>. With reference to <FIG>, the tool <NUM> also has first and second inner blades or elongate members <NUM>, <NUM>. The blades <NUM>, <NUM>, <NUM>, <NUM> as shown may have an arc or radius to facilitate a sliding interconnect between the first inner and first outer blades <NUM>, <NUM> and the second inner and second outer blades <NUM>, <NUM>. The blades <NUM>, <NUM>, <NUM>, <NUM>, cooperate to releasably couple to the saddle <NUM> at the distal end <NUM>, as will be explained further below. The outer surfaces of the first and second inner blades <NUM>, <NUM> slidingly engage the inner surfaces of the first and second outer blades <NUM>, <NUM> such that the first and second blades <NUM>, <NUM> have an unlocked position <NUM> where the tool <NUM> is releasably engageable with the saddle <NUM> and a locked position <NUM> where the tool <NUM> is locked to the saddle <NUM>.

The proximal end <NUM> further comprises a connector <NUM> that releasably couples the blades <NUM>, <NUM>, <NUM>, <NUM><NUM> at the proximal end <NUM> of the tool, as also will be explained further below. The connector <NUM> is adapted to couple the blades <NUM>, <NUM>, <NUM>, <NUM> at the proximal end <NUM> but does not cause relative movement of the first and second inner blades <NUM>, <NUM><NUM> with respect to the first and second outer blades <NUM>, <NUM>. When connector <NUM> is coupled to the tool <NUM>, the first and second inner blades <NUM>, <NUM>, and the first and second outer blades <NUM>, <NUM> may be considered inner and outer sleeves, tubes, lumen, or the like. When the connector <NUM><NUM> is removed, however, the blades are not otherwise interconnected. Removing the interconnection provides a channel, defined below, over the entire length of the tool <NUM>.

With continued reference to <FIG> and <FIG>, one possible saddle <NUM> will be further described. The saddle <NUM> comprises a through bore <NUM> with a bore axis <NUM> generally aligned with the vertical longitudinal axis <NUM>. The saddle <NUM> also comprises a plurality of legs <NUM><NUM> (or arms) forming a U-shaped channel <NUM> having a rod seat <NUM>. The through bore <NUM> is configured to receive a bone fastener as is generally known in the art, but not shown for convenience. The U-shaped channel <NUM> and rod seat <NUM><NUM> are configured to receive a fixation rod as is generally known in the art, but not shown for convenience.

With reference to <FIG>, an exemplary attachment mechanism <NUM> and <NUM> for establishing a releasable connection between the inner and outer blades of tool <NUM> and the saddle <NUM> will now be explained. Additional detail regarding the connection is provided in <CIT>. <FIG> shows the tool <NUM> and the saddle <NUM> in a locked position <NUM> and an unlocked position <NUM>. As can be appreciated, the first and second outer blades <NUM>, <NUM> may have a rolled or folded edge <NUM> forming a groove <NUM>. The first and second inner blades <NUM>, <NUM> may have a tongue <NUM> forming a slidable tongue and groove connection between the inner and outer blades.

The attachment mechanism <NUM> is further described with reference to the unlocked position <NUM>. The legs <NUM> of the saddle terminate at an upper surface <NUM>. The upper surface <NUM> has at least one locking detent <NUM> sized to receive a locking protrusion <NUM> extending from a distal end <NUM> of the first and second inner blades <NUM>, <NUM>. In this exemplary embodiment, two locking protrusions <NUM> are provided to engage two locking detents <NUM>. To facilitate the connections, the distal end of the first and second inner blades <NUM>, <NUM> may include a wedge, block, ramp <NUM>, or the like. The ramp <NUM> tends to bias the first and second inner blades radially outwardly.

The attachment mechanism <NUM> is further described with reference to the locked position <NUM>. The legs <NUM> include an outer surface <NUM>. The outer surface <NUM> has a tool shelf <NUM>. The first and second outer blades <NUM>, <NUM> have a ledge <NUM> extending radially inwardly from the distal end <NUM> of the first and second outer blades <NUM>, <NUM>. The ledge <NUM> is sized to engage the shelf <NUM>. The ledge <NUM> and shelf <NUM> may comprise alignment ridges and grooves <NUM>, <NUM> as shown.

When in the unlocked position <NUM>, the first and second blades <NUM>, <NUM> are movable radially outwardly from each other. The first and second blades <NUM>, <NUM> arc initially positioned such that the opposed ledges <NUM> move into the U-shaped channel <NUM>. The first and second blades <NUM>, <NUM> are rotated, either clockwise or counterclockwise, such that the legs <NUM> of the saddle <NUM> force the first and second blades <NUM>, <NUM> radially apart. The U-shaped channel <NUM> may have edges <NUM> that are beveled, tapered, or chamfered to facilitate the movement. The ledge <NUM> may have cooperating edges <NUM>, which may be referred to as leading or trailing edges. The tool <NUM> is rotated and moved vertically until the ledge <NUM> aligns with the shelf <NUM>, at which point the first and second blades move radially inward to "snap fit" onto the saddle <NUM>.

Coupling the ledge <NUM> and shelf <NUM> generally aligns the locking protrusions <NUM> with the locking detents <NUM>. The first and second inner blades <NUM>, <NUM> are slid along the inner surface of the first and second outer blades <NUM>, <NUM> until the locking protrusions <NUM> engage with the locking detents <NUM>. A clamping force is generated between the bottom surface <NUM> of the first and second inner blades <NUM>, <NUM> abutting the upper surface <NUM> of the saddle <NUM> and the ledge <NUM> of the first and second outer blades <NUM>, <NUM> engaging the shelf <NUM>.

The first and second inner blades <NUM>, <NUM> in the locked position provide torsional resistance inhibiting the ability to rotate the tool <NUM> off the saddle <NUM>. The resistance is provided in part because the locking protrusions <NUM> engaging the locking detents <NUM> inhibits the first and second outer blades <NUM>, <NUM> from moving radially outward from each other and the clamping force described above, which inhibits the locking protrusions from skipping out of the locking detents <NUM>.

With reference now to <FIG>, an exploded view of part of the tool <NUM> is shown. <FIG> shows the first outer blade <NUM> and the first inner blade <NUM>. The second outer blade <NUM> and the second inner blade <NUM> would be substantially the same and are not further explained herein. The first outer blade <NUM> has an alignment bore <NUM> that generally aligns with an alignment window <NUM> of the first inner blade <NUM>. The alignment bore <NUM> has a collar <NUM> extending outwardly from the first outer blade <NUM>. The alignment bore <NUM> and the alignment window <NUM> align in an overlapping fashion, but generally move with respect to each other as will be explained further below.

The alignment bore <NUM> is cylindrical and is sized to rotationally hold a turret <NUM>, which is shown in more detail in <FIG> and <FIG>. The turret <NUM> includes an inside portion <NUM> and an outside portion <NUM>. The inside portion <NUM> terminates in a face <NUM> that is generally aligned with the inside surface of the first and second outer blades <NUM>, <NUM>. Extending from the face <NUM> is a protrusion <NUM> or offset cam, which will be explained further below. The inside portion <NUM> is connected to the outside portion <NUM> by a beam <NUM> or web of material, which is shown in <FIG>. The outside portion <NUM> includes a lever channel <NUM>. The lever channel <NUM> is formed by walls <NUM> and is sized to receive an arm <NUM> of a lever <NUM>. The arm <NUM> includes a rod bore <NUM> that aligns with the hinge bores <NUM>. A rod <NUM> extends through the rod bore <NUM> and the hinge bores <NUM> to pivotally couple the lever <NUM> to the turret <NUM>.

As can be appreciated, the alignment bore <NUM> and the turret <NUM> have generally the same diameter. The beam <NUM> coupling the inside portion <NUM> and the outside portion <NUM> has a reduced diameter and forms a cylindrical gap <NUM> between the inside portion <NUM> and the outside portion <NUM>. An engagement pin <NUM> extends through an engagement bore <NUM> in the collar <NUM> and into the gap <NUM>. The engagement pin <NUM> retains the turret <NUM> in the alignment bore <NUM> and allows for the turret <NUM> to rotate when the lever is moved in a clockwise or counterclockwise direction.

With reference to <FIG> and <FIG>, the turret <NUM> is shown with the tool <NUM> in the unlocked position <NUM> and the locked position <NUM>. In the unlocked position <NUM>, the protrusion <NUM> generally extends from the centerline <NUM> toward the proximal end <NUM> of tool <NUM> as shown in <FIG>. In the locked position <NUM>, the protrusion <NUM> generally extends from the centerline <NUM> toward the distal end <NUM> of tool <NUM>. For reference, in the unlocked position <NUM>, the protrusion <NUM> generally points to <NUM> o'clock and in the locked position <NUM>, the protrusion generally points to <NUM> o'clock. The positions of turret <NUM> in the unlocked position <NUM> and the locked position <NUM> are shown in <FIG>.

<FIG> shows a view of tool <NUM> with connector <NUM> exploded. Connector <NUM>, in this exemplary embodiment, is a threaded connector. An alternative connector is described below. The outer surface of the first and second inner blades includes a top non-threaded panel <NUM> with a threaded panel <NUM> just below the top non-threaded panel <NUM> having a plurality of threads <NUM>. The top non-threaded panel <NUM> and the threaded panel <NUM> extend above the first and second outer blades <NUM>, <NUM>. The first and second outer blades <NUM>, <NUM> terminate in a top ledge <NUM> proximate the collar <NUM>. The top ledge <NUM> is sized to allow the bottom surface <NUM> of connector <NUM> to abut the top ledge. The bottom surface <NUM> facilitates retention of the engagement pin <NUM> in the engagement bore <NUM>.

The collar <NUM> has a flared extension <NUM> that forms a cavity <NUM> between the flared extension <NUM> and the top non-threaded and threaded panels <NUM>, <NUM>. The connector, as shown in <FIG>, is generally a hollow cylindrical tube with a lower threaded portion <NUM> that has threads <NUM> sized to cooperatively engage threads <NUM>. The threads <NUM>, <NUM> may be designed as reverse or "left-handed" such that the connector <NUM> is not inadvertently disengaged during conventional use. The cylindrical tube of connector <NUM> is formed by a wall having a thickness <NUM> sized to cooperatively fit in cavity <NUM>. Threading the connector <NUM> onto the threaded panels <NUM> of the first and second inner blades <NUM>, <NUM> coupled the first outer blade <NUM> and first inner blade <NUM> to the second outer blade <NUM> and the second inner blade <NUM>.

Once the tool <NUM> is coupled and locked to saddle <NUM>, the connector <NUM> may be removed. The first and second inner and outer blades <NUM>, <NUM>, <NUM>, <NUM> generally retain their respective positions in the locked position <NUM> on the implant without the connector <NUM>. Removal of the connector <NUM>, as generally shown in <FIG>, results in a channel <NUM> that extends the entire length of the first and second inner and outer blades <NUM>, <NUM>, <NUM>, <NUM>. Thus, unlike the aforementioned prior art tools, the rod may be inserted using a tool extending anywhere along the length of the channel <NUM>. In other words, when the connector <NUM> is removed, the proximal opening of channel <NUM> is unblocked from access by a horizontal tool or rod and when the connector <NUM> is connected, the proximal opening to channel <NUM> is blocked by the connector <NUM> such that the channel cannot be accessed therefrom by a horizontal tool or rod. The hollow connector <NUM> allows the tool <NUM> to be used with other conventional tools as well.

With reference now to <FIG> and <FIG>, a tool <NUM> with an alternative connector <NUM> is provided. The tool <NUM> has first and second outer blades <NUM>, <NUM> and first and second inner blades <NUM>, <NUM>. The inner and outer blades <NUM>, <NUM>, <NUM>, <NUM> move in sliding relation to each other similar to the tool <NUM> described above. The tool <NUM> similarly has the turret <NUM> rotationally coupled to the blades <NUM>, <NUM>, <NUM>, <NUM> such that rotation of the protrusion <NUM> moves the first and second inner blades <NUM>, <NUM> between the locked and unlocked positions.

The first and second outer blades <NUM>, <NUM> terminate in a collar <NUM> that contains the alignment bore <NUM>. The collar <NUM> of tool <NUM> terminates in the top ledge <NUM>. The top ledge <NUM> comprises the engagement bore <NUM> through which the engagement pin <NUM> extends to reside in the gap <NUM>.

The first and second inner blades <NUM>, <NUM> have a connector lock portion <NUM> extending beyond the top ledge <NUM>. The connector lock portion <NUM> includes a first outer surface <NUM> having a first outer diameter D1 and a second outer surface <NUM> having a second outer diameter D2. The diameter D2 is greater than the diameter D1 such that the second outer surface <NUM> is stepped radially outward from the first outer surface <NUM> forming an overhang <NUM>. The overhang <NUM>, first outer surface <NUM>, and top ledge <NUM> form a groove <NUM>, channel or the like. The connector lock portion <NUM> includes a first inner surface <NUM> having a first inner diameter D3 and a second inner surface <NUM> having a diameter D4. The diameter D4 is greater than the diameter D3 such that the second outer surface <NUM> is stepped radially outward from the first inner surface <NUM> forming a ridge <NUM>. The connector lock portion <NUM> terminates at a crown <NUM>. The crown <NUM> may be flat or sloped. As shown, a portion of the crown <NUM> is sloped from the second outer surface <NUM> down towards the second inner surface <NUM>. The slope, taper, or chamfer may facilitate the insertion of a lock wall as will be explained further below. The connector portion <NUM> has a lock tab <NUM> formed generally by the second outer surface <NUM>, the crown <NUM>, and the second inner wall <NUM>.

The connector <NUM> has a base <NUM> with an inner rail <NUM>. The inner rail <NUM> has a rail diameter D5 that is approximately equal to diameter D1 such that the inner rail <NUM> resides in groove <NUM>. Adjacent the rail <NUM> is a ring <NUM>. The ring <NUM> has a ring diameter D6 that is approximately equal to the diameter D2 such that the lock tab <NUM> resides in the ring <NUM>.

The connector <NUM> comprises a hollow interior <NUM> to receive a movable barrel <NUM>. The connector <NUM> connects first and second inner and outer blades <NUM>, <NUM>, <NUM>, <NUM> by movement of the barrel <NUM> from an unlocked position <NUM> (shown in <FIG>) where the first and second inner blades <NUM>, <NUM> at the connector portion <NUM> may move radially inwardly to be snap fit with the connector <NUM> and a locked position <NUM> (shown in <FIG>) where the barrel forms a lock wall <NUM> to retain the lock tab <NUM> in the ring <NUM> such that the first and second inner blades <NUM>, <NUM> cannot move sufficiently radially inwardly to disengage from the connector <NUM>. The barrel <NUM> has a bottom stop <NUM> that is supported by the ridge <NUM>. The barrel <NUM> also is generally hollow to allow tool access. The barrel <NUM> proximate the bottom stop <NUM> has an inner diameter D7 approximately equal to diameter D3 and an outer diameter D8 approximately equal to diameter D4.

Claim 1:
A system for facilitating minimally invasive surgical procedures, the system comprising a tool (<NUM>, <NUM>) and an implant wherein the implant is a saddle (<NUM>), the tool comprising:
first and second outer blades (<NUM>,<NUM>) each having a distal end (<NUM>) and a proximal end (<NUM>);
first and second inner blades (<NUM>,<NUM>) each having a distal end (<NUM>) and a proximal end (<NUM>), the first and second inner blades (<NUM>,<NUM>) operable to slidingly engage the first and second outer blades (<NUM>,<NUM>), wherein the first and second inner blades (<NUM>,<NUM>) have with respect to the first and second outer blades, an unlocked position (<NUM>) where the tool (<NUM>, <NUM>) is releasably engageable with the saddle (<NUM>)and a locked position (<NUM>) where the tool (<NUM>, <NUM>) is locked to the saddle (<NUM>);
a channel (<NUM>) formed between the first inner and outer blades (<NUM>,<NUM>) and the second inner and outer blades (<NUM>, <NUM>), the channel (<NUM>) extending along an entire length of the first and second inner and outer blades(<NUM>,<NUM>,<NUM>,<NUM>); and
a hollow connector (<NUM>) releasably coupled to the proximal end (<NUM>) of the first and second inner blades (<NUM>,<NUM>),
wherein a proximal end (<NUM>) of the channel (<NUM>) is blocked and the first and second inner blades (<NUM>, <NUM>) are interconnected at respective proximal ends (<NUM>) when the hollow connector (<NUM>) is coupled to the first and second inner blades (<NUM>,<NUM>), and
wherein the proximal end (<NUM>) of the channel (<NUM>) is unblocked and the first and second outer blades (<NUM>, <NUM>) are separate and not interconnected at respective proximal ends (<NUM>) when the hollow connector (<NUM>) is removed from the first and second inner blades (<NUM>,<NUM>) so that the channel (<NUM>) is provided over the entire length of the tool (<NUM>,<NUM>).