Patent Description:
During spine surgery, such as procedures to correct deformities in the spine, fixation constructs are often assembled to hold the spine in a desired shape. Such constructs often include a plurality of implanted bone anchors along multiple vertebrae and a connecting spinal fixation element, such as a rod, that is received within a head of each of the bone anchors and secured using a set screw. In many cases, the bone anchors are first implanted in the vertebrae, a rod is then positioned relative to the bone anchor heads, and set screws applied to secure the rod relative to each bone anchor.

Current posterior fixation systems that utilize the above-described implanted bone anchors and spinal fixation rods or elements coupled to the anchors require the delivery of set screws to each implanted anchor to secure the rod relative to the anchor. For each set screw/implanted anchor, a user must connect a set screw to an insertion instrument and deliver this assembly to the implanted bone anchor, often through narrow extension tubes, guides, or other instrumentation that extends from the implanted bone anchor away from the patient's body and toward the user performing the surgery. Further, in many cases a first user, such as an assistant, loads the set screw on the insertion device and passes this assembly to a second user, such as a surgeon, who introduces the assembly into the patient's body and delivers the set screw. The second user then returns the insertion device to the first user for reloading and the process repeats for each implanted bone anchor-of which there may be several, especially in spinal deformity correction procedures where especially long spinal fixation constructs may be assembled. This process requires some amount of operative time, which can become significant. Each pass also adds complexity and risk to the procedure that a component might be mishandled, dropped, etc..

Accordingly, there is a need for improved instruments for delivering set screws, including improved instruments for delivering multiple set screws to secure components to bone anchors during spine surgery while minimizing loading time of the instrument. <CIT> provides an instrument according to the preamble of claim <NUM>, with <CIT>, <CIT> and <CIT> providing examples of other instruments.

The present disclosure generally relates to multiple set screw insertion instruments that address challenges of prior approaches. The multiple set screw insertion instruments disclosed herein can reduce the number of passes of instruments between a surgeon and assistant while maintaining the ability to deliver set screws to affix spine surgery instrumentation. Actuation of the instrument can result in relative movement between an inner driver shaft and an outer sleeve to sequentially eject set screws from the instrument into a bone anchor receiver head or other spinal instrumentation.

According to the invention, a surgical instrument is provided that comprises a shaft with a distal portion configured to drive a set screw and seat a plurality of set screws stacked against one another on the shaft, a handle coupled to the shaft, a sleeve disposed over the shaft and configured to contact a proximal-most set screw stacked on the shaft, a first button disposed in the handle and configured to advance the sleeve distally relative to the shaft by a first increment, and a second button disposed in the handle and configured to permit retraction of the sleeve proximally.

Any of a variety of alternative or additional features can be included and are considered within the scope of the present disclosure as defined by the claims. For example, in some embodiments, the sleeve can include a plurality of ratchet teeth. In certain embodiments, the first increment can correspond to a distance between two adjacent teeth of the plurality of ratchet teeth. In some embodiments, the instrument can further include a detent disposed in the handle that is configured to interface with the plurality of ratchet teeth to resist movement of the sleeve. The detent can be a spring-biased ball in certain embodiments. In some embodiments, the second button can be biased to contact a ratchet tooth of the plurality of ratchet teeth. And in certain embodiments, the second button can permit proximal retraction of the sleeve when the bias of the second button is overcome.

In some embodiments, the instrument can further include a spring clip disposed around a distal end of the shaft and configured to retain a set screw thereon by interference fit.

In certain embodiments, movement of the first button can cause movement of the second button. In some embodiments, movement of the first button can translate the second button distally. Further, in some embodiments the first button can be biased proximally such that proximal movement of the first button moves the second button proximally relative to the sleeve.

In some embodiments, an outer diameter of the plurality of set screws stacked on the shaft can be substantially equal to an outer diameter of the sleeve disposed over the shaft.

In certain embodiments, the sleeve can also include a retention mechanism thereon for preventing ejection of the sleeve from the handle. The retention mechanism can abut the second button to retain the sleeve within the handle in certain configurations.

In some embodiments, the first button can be disposed on a proximal end of the handle and the second button can be disposed on a side of the handle.

In certain embodiments, any of the first button and the second button can be biased.

In background information, a surgical method is provided that can include delivering a first set screw to a first implanted bone anchor using an inserter, actuating the inserter to advance a second set screw distally relative to a shaft of the inserter, and delivering a second set screw to a second implanted bone anchor using the inserter.

The background information methods disclosed herein can include any of a variety of additional or alternative steps that are considered within the scope of the present disclosure. In some examples, actuating the inserter can include depressing a first button disposed in a handle of the inserter. Further, in some examples actuating the inserter can include advancing a sleeve disposed over the shaft distally to urge the second set screw toward a distal end of the shaft.

In background information, a surgical method is provided that can include actuating a first button disposed in a handle of an inserter, sliding a sleeve disposed over a shaft of the inserter proximally, and advancing a plurality of set screws proximally over a distal portion of the shaft of the inserter.

In some embodiments, the first button can be disposed in a side of the handle. And in certain embodiments, the sleeve can slide to abut a proximal wall of a recess formed in the handle.

The embodiments of the present disclosure can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:.

Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices, systems disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. The devices and systems specifically described herein and illustrated in the accompanying drawings are non-limiting embodiments.

The present disclosure generally relates to an instrument, such as multiple set screw insertion instruments, that address challenges of prior approaches. The multiple set screw insertion instrument disclosed herein can reduce the number of passes of instruments between a surgeon and assistant while maintaining the ability to deliver set screws to affix spine surgery instrumentation. In one embodiment, the multiple set screw insertion instrument include a shaft, such as an inner driver shaft, having a plurality of set screws stacked thereon, and a sleeve, such as an outer driver sleeve, having a ratcheting portion for stepwise advancement of set screws along the inner driver shaft for insertion into bone anchors and other spinal instrumentation. The inner driver shaft is, and the outer sleeve can be, received within a handle having a button for actuating the instrument. Actuation of the instrument can result in relative movement between the inner driver shaft and the outer sleeve to sequentially eject set screws from the instrument into a bone anchor receiver head or other spinal instrumentation.

<FIG> illustrate one embodiment of a multiple set screw insertion instrument or inserter instrument <NUM>. The multiple set screw insertion instrument <NUM> is used to deliver set screws to spinal instrumentation during procedures, e.g., spinal surgery. The instrument <NUM> includes an inner driver shaft <NUM>, an outer sleeve <NUM>, and a handle <NUM> configured to receive the inner driver shaft <NUM> and the outer sleeve <NUM> therein. Further, the instrument <NUM> includes a central longitudinal axis A1 extending therethrough such that the axis A1 passes through one or more of the inner driver shaft <NUM>, the outer sleeve <NUM>, and/or the handle <NUM>. In use, the inner driver shaft <NUM> is received inside the outer sleeve <NUM>, with the outer sleeve being configured to translate relative to the inner driver shaft <NUM>. Translation of the outer sleeve 104rmsequentially advances a set screw <NUM> of the plurality of set screws <NUM> to a distal tip <NUM> located on the drive feature <NUM> of the inner driver shaft <NUM> after ejection of a previous set screw from the instrument, e.g., due to insertion of the previous set screw into spinal implementation.

<FIG> in particular illustrate assembly of the multiple set screw insertion instrument <NUM>. The inner driver shaft <NUM> can include a generally tubular body <NUM> having a proximal end 102p and a distal end 102d with the central longitudinal axis A1 extending therebetween. The tubular body <NUM> can be solid, though in some embodiments, the body can be hollow such that an opening extends therethrough. The proximal end 102p of the inner driver shaft <NUM> can include a mating feature <NUM>, e.g., a threaded male member, as shown in <FIG>, for coupling with a corresponding threaded bore <NUM> in the handle <NUM>, as described in greater detail below with regard to <FIG>. In some embodiments, the mating feature <NUM> can be keyed to be received within the bore in a specific orientation such that the inner driver shaft <NUM> couples to the handle <NUM> in a specific orientation.

The drive feature <NUM> at the distal end 102d of the inner driver shaft <NUM> can be shaped to correspond to an inner opening in the plurality of set screws <NUM>. As shown, the drive feature <NUM> can be a male Torx®-shaped protrusion extending along a distal portion of the shaft <NUM> such that a plurality of set screws <NUM> can be stacked on the drive feature <NUM>. The plurality of set screws <NUM> can include a recess shaped to correspond to the drive feature <NUM> to allow the set screws to be secured to the drive feature and rotated therewith while also allowing for proximal translation of the set screws over the drive feature <NUM>. In some embodiments, the drive feature <NUM> can include a retention feature <NUM>, as shown in <FIG>, to prevent unintended separation of the set screws <NUM> from the drive feature <NUM>. Further details of the retention feature are discussed in greater detail below.

The overall profile of the inserter instrument <NUM> can be similar to an elongate set screw driver. The outer sleeve <NUM> can include a generally tubular body <NUM> having proximal and distal ends 104p, 104d defining a channel <NUM> therebetween. The channel <NUM> can extend in a common axis of the central longitudinal axis A1 of the inner driver shaft <NUM> such that the central longitudinal axis A1 extends from the proximal end 104p to the distal end 104d of the outer shaft <NUM>. As shown, the channel <NUM> can be configured to receive at least a portion of the inner driver shaft <NUM> therethrough. For example, the body <NUM> of the outer sleeve <NUM> can define an inner diameter ID that is substantially the same size or larger than an outer diameter OD of the inner driver shaft <NUM> to receive the inner driver shaft <NUM> therethrough.

In some embodiments, the outer sleeve <NUM> can include a non-uniform outer diameter OD1. For example, the outer diameter OD1 of the tubular body <NUM> of the outer sleeve <NUM> can be larger in some locations than at others. In some embodiments, the outer diameter OD1 can taper along a length thereof. In some embodiments, the outer sleeve <NUM> can taper from the proximal end 104p of towards the distal end 104d such that the proximal end 104p engages one or more features within the handle <NUM> to selectively permit or prevent translation of the outer sleeve <NUM> relative to the handle and/or the inner driver shaft <NUM>. As shown, the outer sleeve <NUM> can include a proximal head <NUM> thereon having a larger outer diameter OD1 than a portion of the sleeve extending distally from the proximal head. The proximal head <NUM> can function as a retention mechanism that prevents inadvertent or undesired separation of the sleeve <NUM> from the handle <NUM>. For example, the proximal head <NUM> can interface with the pawl, latch or button <NUM> to provide a stop against complete removal of the sleeve <NUM> from the handle <NUM>. The stop can prevent axial translation of the outer shaft <NUM> with respect to the other components of the inserter instrument <NUM>. While a proximal head <NUM> is shown, the stop can include a ribbed surface, a protrusion, a catch, or another component configured to retain the outer sleeve <NUM> within the handle <NUM>.

The outer sleeve <NUM> can include a ratchet portion <NUM> formed along the tubular body <NUM>. As shown, the ratchet portion <NUM> can extend along an intermediate section of the outer sleeve <NUM>, though in some embodiments, the ratchet portion <NUM> can extend along any length of the sleeve. The ratchet portion <NUM> can include a series of ratchet teeth, ribs, or protrusions <NUM> that are formed along the outer surface of the outer sleeve <NUM>. The ratchet portion <NUM> can engage with one or more components of the instrument <NUM>, such as the pawl <NUM> discussed below, for step-wise advancement of the outer shaft <NUM> with respect to other components, as discussed in greater detail below. The ratchet portion <NUM> can extend around a circumference of the tubular body <NUM> to allow the outer sleeve <NUM> to be inserted into the handle <NUM> in any rotational orientation. In use, the ratchet portion <NUM> can allow the outer sleeve <NUM> to provide a hard stop behind a set screw, which can aid a user in starting to thread the set screw into the implant and prevent proximal movement of the set screw or outer sleeve if a user exerts axial pushing forces on the device during insertion. In addition, the ratchet portion <NUM> can facilitate the advancement of a next set screw toward a distal end of the driver shaft <NUM> in connection with insertion of a prior set screw into a spinal fixation construct, such as a bone screw receiver member.

The handle <NUM> can include a tubular body <NUM> having a central lumen <NUM> formed therein. The central lumen <NUM> can extend from a distal end 106d of the handle <NUM> to the proximal end 106p along the central longitudinal axis A1 of the instrument <NUM> to receive one or more of the inner driver shaft <NUM> and/or the outer sleeve <NUM> therethrough. The central lumen can include an inner diameter ID2 that can be substantially the same as or larger than an outer diameter OD1 of the outer sleeve <NUM> to allow the outer sleeve to be disposed within the central lumen <NUM>.

The central lumen <NUM> can include a receiving portion <NUM> at the proximal end 106p of the handle <NUM>. The receiving portion <NUM> can extend within the central lumen <NUM> to receive the proximal end 102p of the inner driver shaft <NUM> therein. As shown in greater detail in <FIG>, the receiving portion <NUM> can include a bore <NUM> having a reduced diameter portion that lies along the central longitudinal axis A1 with the central lumen <NUM>. In some embodiments, the receiving portion <NUM>, or a section of thereof, can be threaded. For example, as discussed above, the receiving portion <NUM> can include threads <NUM> thereon to allow threading of the inner driver shaft <NUM> thereto. During assembly, the proximal end 102p of the inner driver shaft <NUM> can be inserted into the receiving portion <NUM> with the mating feature <NUM> threaded into the threads <NUM> to couple the inner driver shaft <NUM> to the handle <NUM>.

The receiving portion <NUM> can include a lumen <NUM> formed therein. For example, the threads <NUM> can extend through the receiving portion <NUM> and terminate at, or proximate to, the lumen <NUM>. The lumen <NUM> can receive one or more coupling features of the instrument <NUM> therein, as described in greater detail below. The handle <NUM> can include a recess <NUM> formed at a proximal end 106p thereof. For example, as shown, the receiving portion <NUM> can terminate distal to the proximal end 106p of the handle <NUM> to define the recess <NUM> therebetween. The recess <NUM> can receive one or more components that are configured to actuate the instrument. As shown, a button <NUM> is disposed within the handle <NUM> to control advancement of the outer sleeve <NUM> to urge the set screws <NUM> distally.

The handle <NUM> can be made from a variety of materials, including any of a variety of plastics, ceramics, or metals, among others. In some embodiments, the handle <NUM> can include over-moldings of multiple materials, such as a silicone over-molding formed on another underlying material. The handle <NUM> can include a series of openings <NUM> at the distal end 106d thereof to allow for components of the instrument <NUM> to facilitate operation thereof. The series of openings <NUM> can extend transversely into the central lumen <NUM> to be in communication with the outer sleeve <NUM> disposed therein. The series of openings <NUM> are discussed in greater detail with respect to <FIG> below.

<FIG> illustrates a plurality of set screws <NUM> that can be used with the multiple set screw insertion instrument <NUM> of the present disclosure. As shown, each set screw in the plurality of set screws <NUM> can include a female drive feature or through-bore <NUM> cut completely therethrough. The set screws <NUM> can be stacked on top of one another such that an axis A passing therethrough aligns with the central longitudinal axis A1. The female drive feature <NUM> can be configured to receive the male drive feature <NUM> of the inner driver shaft <NUM> therethrough to dispose the stack of set screws <NUM> along the inner driver shaft. For example, the through-bore <NUM> can include a geometry complementary to the drive feature <NUM> to allow the set screw <NUM> to stack onto the inserter shaft <NUM> and be rotationally driven by the inserter shaft <NUM> when the inserter instrument <NUM> is rotated. The through-bore <NUM> can be sized to allow for axial translation of each of the set screws <NUM> along the drive feature <NUM> when the outer sleeve <NUM> is advanced relative to the inner driver shaft <NUM>. Moreover, each set screw can have an outer diameter OD2 and the profile of the outer sleeve <NUM> can, in some embodiments, be no larger than the outer diameter OD2 of the set screws <NUM>.

<FIG> illustrate the inserter instrument in greater detail. As shown, the inserter instrument <NUM>, when placed in an initial position, includes the inner driver shaft <NUM> disposed within the channel <NUM> of the outer sleeve <NUM>, with both components received within the central lumen <NUM> of the handle <NUM>. Specifically, as noted above, the mating feature <NUM> of the inner driver shaft <NUM> can be threaded into the threads <NUM> within the receiving portion <NUM>, while the proximal end 104p of the outer sleeve <NUM> can abut the receiving portion <NUM>. The plurality of set screws <NUM> can be disposed on the drive feature <NUM> of the inner driver shaft <NUM> distal to the outer sleeve <NUM>.

<FIG> illustrates a relationship between the stack of set screws <NUM> and the inner driver shaft <NUM> in greater detail. As noted above, the inner driver shaft <NUM> can include a retention feature <NUM>, e.g., a spring clip or a circlip, which engages a distal tip <NUM> of the drive feature <NUM>. As shown in <FIG>, the spring clip <NUM> disposed at the distal end of the drive feature <NUM> can provide an interference fit between the spring clip and set screw <NUM>, thereby limiting unwanted distal translation between the set screws and the drive feature.

<FIG> illustrates the interaction of the inner driver shaft <NUM>, the outer sleeve <NUM>, and the handle <NUM> of the inserter instrument <NUM> while in the initial position described above. The outer shaft <NUM> is received within the central lumen <NUM> while the proximal head <NUM> abuts the receiving portion <NUM>. The bore <NUM> can receive a biasing element <NUM>, such as a coil spring, that is configured to compress and extend in an axial direction when engaged with one or more components of the instrument <NUM>. For example, as shown, the biasing element <NUM> can be disposed between the receiving portion <NUM> and the button <NUM>. The biasing element <NUM> can bias the button <NUM> proximally such that the button <NUM> at least partially extends out of the recess <NUM>.

<FIG> illustrates the button <NUM> in greater detail. As shown, the button <NUM> includes a proximal head <NUM> and a distal body <NUM> extending therefrom. The proximal head <NUM> can include an outer diameter (not shown) that is substantially the same or smaller than a diameter of the recess <NUM> to allow the head to be disposed within the recess <NUM>. The head <NUM> can include a distal-facing surface <NUM> for engaging a portion of the biasing element <NUM> to compress the biasing element when the button <NUM> is actuated. In some embodiments, the proximal head <NUM> can include a bore <NUM> formed therein.

The distal body <NUM> can include a sidewall <NUM> that extends from the proximal head <NUM> and runs along an interior portion of the inserter instrument handle <NUM>. For example, the handle <NUM> can include a lumen <NUM> formed therein to allow the distal body <NUM> to pass therethrough. The lumen <NUM> can, in some embodiments, be separate from the central lumen <NUM>. As shown in <FIG>, the lumen <NUM> can terminate within an interior of the handle <NUM>, e.g., distal to the receiving portion <NUM>. In some embodiments, however, the second lumen <NUM> can extend through a distal end of the handle <NUM>.

The distal body <NUM> can include one or more access points in the sidewall <NUM> thereof. The access points can align with one or more of the openings <NUM> in the handle <NUM> to facilitate advancement or indexing of the outer sleeve <NUM> relative to the handle. For example, the distal body <NUM> can include a cutout <NUM> formed therein that forms a pair of flanges <NUM>, <NUM>. The cutout <NUM> can align with one or more of the series of openings <NUM> in the handle <NUM>, as noted above, to allow another component to extend through the handle <NUM> and the distal body <NUM> simultaneously and engage the outer sleeve <NUM>, as discussed further below. As shown, one or more transverse openings <NUM>, <NUM> can be formed in each of the flanges <NUM>, <NUM> to facilitate coupling between components disposed within the cutout <NUM>.

Access points can be formed in an outer surface of the sidewall <NUM>. For example, the illustrated top surface of the sidewall <NUM> in <FIG> can include a recess <NUM> for receiving a biasing element <NUM>, such as a coil spring or other biasing element. The biasing element <NUM> can, for example, bias another component disposed in the cutout <NUM> such that a portion thereof extends into the central lumen <NUM> to engage the outer shaft <NUM>, as described in more detail below. One embodiment of such a component can be a pawl, latch, or button <NUM> (see <FIG>) that extends into the central lumen <NUM> to engage the outer shaft <NUM>. For example, the feature <NUM> can extend from a distal end 178d to a proximal end 178p, with the distal end 178d having an engagement surface <NUM> thereon. The engagement surface <NUM> can extend radially inward from the cutout <NUM> of the button <NUM> and the opening <NUM> of the handle <NUM> to engage the ratchet portion <NUM> of the outer sleeve <NUM>. The pawl <NUM> can be coupled to the button <NUM> by a pin <NUM> received in the openings <NUM>, <NUM> of the flanges <NUM>, <NUM>. The pin <NUM> can allow the pawl <NUM> to pivot about an axis of the pin <NUM>. The proximal end 178p of the pawl <NUM> can include a recess to receive one end of the biasing element <NUM>. The biasing element <NUM> can thereby urge the proximal end of the pawl 178p radially outward and the distal end of the pawl 178d radially inward toward the outer sleeve <NUM> and ratchet portion <NUM>.

The sidewall <NUM> can include a slot <NUM> configured to receive a pin <NUM>. The pin can be anchored within a bore formed in the sidewall of the handle <NUM> such that the pin does not translate axially relative to the handle. The slot can extend axially along the distal body <NUM> to allow axial translation of the button <NUM> between a proximal position and a distal position as defined by a length of the slot <NUM>. Motion of the slot <NUM> relative to the pin <NUM> can define limits of translation of the distal body <NUM> and button <NUM> during actuation of the inserter instrument <NUM>. For example, actuation of the button <NUM> can advance the distal body <NUM> until the pin <NUM> reaches a proximal end of the slot <NUM>. Retraction of the button <NUM> can likewise move the pin <NUM> to the distal end of the slot <NUM>, and interference between the pin and the end of the slot can prevent further movement of the button <NUM>.

The inserter instrument <NUM> can also include a detent <NUM>, such as a spring plunger or ball detent, received through an opening <NUM> in the handle <NUM>. The detent <NUM>, which is illustrated as a ball bearing biased radially inward by a coil spring, can engage the ratchet portion <NUM> to resist movement of the outer sleeve <NUM> relative to the handle <NUM>. This can prevent undesired proximal or distal movement of the outer sleeve <NUM> relative to the handle <NUM>, and can be particularly useful in preventing proximal movement of the outer sleeve <NUM> with the button <NUM> when the button retracts proximally after actuation. It will be appreciated that, in some embodiments, a leaf spring, a cantilevered deformable element, or other component can be used in place of the illustrated spring plunger of the instrument <NUM>.

<FIG> illustrate actuation of the multiple set screw insertion instrument <NUM> in greater detail. As shown in <FIG>, the button <NUM> of the multiple set screw insertion instrument <NUM> can, in an initial position, protrude proximally from the proximal end of the handle <NUM>. Once actuated, as shown in <FIG>, the resistance of the biasing element <NUM> can be overcome and the button <NUM> can move distally into the recess <NUM> of the handle <NUM>.

<FIG> illustrate a sequence of use of the multiple set screw insertion instrument <NUM> to insert a set screw during a procedure. Similar to <FIG>, <FIG> shows the multiple set screw insertion instrument <NUM> in an initial position with a plurality of set screws <NUM> stacked onto a distal portion of the inner driver shaft <NUM>. In this configuration, the first button <NUM> is biased to a proximal-most position and the pawl or second button <NUM> is biased to a position where its distal end engagement surface <NUM> is received within a distal-most recess <NUM> of the ratchet portion <NUM> of the outer sleeve <NUM>. The outer sleeve <NUM> is prevented from proximal movement relative to the driver shaft <NUM> and handle <NUM> by interaction between the proximal end of the outer sleeve and the handle receiving portion <NUM>, as well as by the interaction of the ratchet portion <NUM> with the pawl <NUM>, which is in turn limited by interaction of the pin <NUM> and the slot <NUM>. Accordingly, a user can urge a distal-most set screw to be placed into, e.g., a receiving member of a bone anchor to couple the set screw thereto. Axial and rotational forces can be transferred to the distal-most set screw to facilitate insertion thereof. Once the set screw <NUM> is coupled to the bone anchor, the multiple set screw insertion instrument <NUM> can be withdrawn proximally such that the distal-most set screw overcomes any resistive force from a retention feature <NUM> and comes off the driver shaft <NUM>. Alternatively or in addition, a user can depress the button <NUM> to advance the outer sleeve <NUM> relative to the driver shaft <NUM>, as described below, to aid in ejecting the distal-most set screw from the device.

As shown in <FIG>, the drive feature <NUM> and the distal tip <NUM> of the inner driver shaft <NUM> can be exposed once the set screw is coupled to the bone anchor and the instrument is withdrawn proximally to decouple the distal-most set screw from the instrument. To advance the stack of set screws <NUM> distally towards the tip <NUM>, the button <NUM> can be actuated, as shown in <FIG>. Actuation of the button <NUM> can overcome the force of the biasing element <NUM> and distal advancement of the button <NUM> includes advancement of the distal body <NUM> within the lumen <NUM> relative to the handle <NUM>. Advancement of the distal body <NUM> includes advancement of the pawl <NUM>. The pawl <NUM>, which is engaged with the distal-most recess <NUM> of the ratchet portion <NUM>, urges the outer sleeve <NUM> distally along with the pawl and button <NUM>. The actuation of the button can also provide sufficient force to overcome the resistance of the detent <NUM> against movement of the outer sleeve <NUM>.

Distal advancement of the outer sleeve <NUM> terminates when the pin <NUM> abuts the proximal end of the slot <NUM> and the distal-facing surface <NUM> of the button <NUM> reaches the proximal end of the recess <NUM>. In such a position, the new distal-most set screw can be positioned proximate to the distal tip <NUM> of the driver shaft <NUM>. In this orientation, as shown in <FIG>, the detent <NUM> can engage a second recess <NUM> of the ratchet portion <NUM> to again provide a resistive force against movement of the outer sleeve <NUM>. The button <NUM> can then be released and the biasing element <NUM> can return the button <NUM> to its proximal-most position. This can, in turn, urge the pawl <NUM> proximally. The resistance provided by the detent <NUM> can overcome the friction force between the pawl <NUM> and the ratchet portion <NUM> of the outer sleeve <NUM> such that the outer sleeve remains stationary relative to the handle <NUM> and the pawl <NUM> rides into the second recess <NUM> of the ratchet portion <NUM> as it moves proximally relative to the handle <NUM> and the outer sleeve <NUM>. In the absence of the detent <NUM>, the outer sleeve <NUM> could retract proximally with the pawl or button <NUM> due to the friction force between them. Once the button <NUM> returns to its proximal, initial orientation, the set screw insertion process can be repeated until the stack of set screws <NUM> along the inner driver shaft <NUM> have all been inserted into their desired locations and ejected from the insertion instrument.

<FIG> illustrates the inserter instrument <NUM> following insertion of several set screws <NUM>, such that a single set screw remains disposed thereon. As shown, the pawl or second button <NUM> and the detent <NUM> are engaged with a proximal-most recess of the ratchet portion <NUM> of the outer sleeve <NUM>. <FIG> illustrates a detail view of the distal tip of the instrument <NUM>, where the set screw is engaged with the retention feature <NUM> to prevent dislodgement of the set screw therefrom. The retention feature <NUM> can include a spring clip or circlip that surrounds the distal tip <NUM> and provides a radially-outward interference fit with the female drive recess or bore formed in the set screw <NUM>. The spring clip <NUM> can be deformed to reduce its outer diameter, thereby allowing the application of sufficient force from the outer sleeve <NUM> to urge the set screw <NUM> over the clip and eject it from the instrument <NUM>.

Alternate embodiments of the drive feature formed on the distal portion of the driver shaft <NUM> and the retention feature <NUM> are shown in <FIG>. While a spring clip or circlip is discussed above, other embodiments are possible. As shown in these figures, the retention feature <NUM> can include a opposed ball detents that extend transversely from the distal tip of the driver shaft <NUM>. The opposed ball detents can be biased by a spring <NUM> or another biasing element. The driver shaft <NUM> can include a protruding distal tip <NUM> at the distal end of a drive feature <NUM>, as shown in <FIG>. The protruding distal tip <NUM> can have a cylindrical profile, a diameter substantially the same as or less than a minor diameter of the drive feature <NUM>, and can include chamfered or tapered edges to help facilitate insertion of the driver shaft and set screw disposed thereabout into, e.g., a bone screw receiver head. In other embodiments and as shown in <FIG>, the driver shaft <NUM> can include a drive feature <NUM> that extends to the distal tip of the driver shaft and a retention feature <NUM> can be incorporated into the drive feature without a protruding distal tip having a different profile from the drive feature.

<FIG> illustrate another embodiment of a retention feature <NUM> that can be incorporated into a driver shaft <NUM>. The retention feature <NUM> can include a leaf spring or other resilient element disposed within a recess formed in the driver shaft <NUM>. In the embodiment of <FIG>, the spring <NUM> resembles a wishbone or U-shape with a proximal end anchored within the shaft <NUM> and distal ends that protrude through opposed openings formed in the outer surface of the shaft. The protruding distal ends of the leaf spring <NUM> can be configured to retain set screws to the driver shaft via an interference fit, similar to the other retention feature embodiments described above. <FIG> illustrates an embodiment wherein a more linear spring element <NUM> provides a single protrusion from a single opening formed on the outer surface of the shaft <NUM>. In embodiments where a resilient element is anchored within a driver shaft, the shaft can be provided in two pieces, e.g., a distal piece 402d and a proximal piece 402p shown in <FIG>, such that the resilient element <NUM> can be positioned within recesses formed in each piece and the pieces can subsequently be coupled, e.g., at joint <NUM> by adhesive, welding, mechanical fastening, etc. Any of the above-described drive feature and retention feature embodiments can be utilized with any of the embodiments of a multiple set screw insertion instrument disclosed herein.

In addition, the various other components of the multiple set screw inserter instrument can be configured to provide different interactions with the retention features utilized to hold a set screw against inadvertent ejection from the instrument. For example, in some embodiments the device can be configured to position a set screw just proximally of a retention feature such that a distal-facing surface of the distal-most set screw abuts a portion of the retention feature. In other embodiments, however, the instrument can be configured such that a distal-most set screw is disposed over the retention feature, such that a radially-inner-facing surface of the set screw abuts a radially-outer-facing portion of the retention feature. The different configurations can be accomplished by tuning one or more of the lengths of the outer sleeve, inner shaft, ratchet portion, and first button to achieve desired spacing and advancement. Electing to use one configuration or another can produce different tactile feedback for a user. For example, in an embodiment where the distal-most set screw stacks proximally of the retention feature, a user might feel or overcome one resistance during actuation of the first button, i.e., as the distal-most set screw is advanced over the retention feature (first resistance) and a next set screw is advanced just to abut the retention feature. In another embodiment where the distal-most set screw is positioned over the retention feature, a user might feel or overcome two resistances during actuation of the first button, i.e., as distal-most set screw is ejected off the retention feature (first resistance) and a next set screw is advanced over top of the retention feature (second resistance). Any of the various embodiments disclosed herein can be configured to operate in either manner.

As noted above, the outer sleeve <NUM> can include the proximal head <NUM> that can function as a retention mechanism against inadvertent separation of the outer sleeve <NUM> from the device after ejection of all set screws. <FIG> illustrates the proximal head <NUM> being used to prevent the outer shaft <NUM> from falling distally out of the central lumen <NUM> and off the inner shaft <NUM>. By way of further explanation, once the pawl or second button <NUM> is no longer engaged with the ratchet portion <NUM> of the outer sleeve <NUM>, distal advancement of the outer sleeve can continue substantially uninterrupted until the pawl <NUM> engages the proximal head <NUM>, which can have an outer diameter that is substantially the same as the outer or major diameter of the ratchet portion <NUM> in some embodiments. Friction between the engagement surface <NUM> at the distal end 178d of the pawl and the proximal head <NUM> can prevent separation of the outer sleeve <NUM> from the central lumen <NUM>. In order to separate the outer sleeve <NUM> from the remainder of the instrument, a user can depress the proximal end 178p of the pawl or second button <NUM> to withdraw the distal end 178d radially outward and provide clearance for the proximal head <NUM> to pass distally out of the lumen <NUM> of the handle <NUM>. In some embodiments, the proximal head <NUM> can include a distal-facing surface having a tapered diameter to provide a lead-in which can allow a user to remove the outer sleeve <NUM> by application of sufficient force without separately depressing the second button <NUM>.

<FIG> illustrate the process of at least partially assembling the instrument and loading set screws. In <FIG>, the outer sleeve <NUM> is shown being assembled to the remainder of the instrument <NUM>. The outer sleeve <NUM> can be inserted over the driver shaft <NUM> proximally and, upon entering the lumen <NUM> of the handle <NUM>, its proximal end can abut the distal end 178d of the pawl or second button <NUM>. In some embodiments, the proximal end 178p of the pawl or second button <NUM> can be pressed to compress the spring <NUM>, pivot the distal end 178d radially outward, and allow the outer sleeve <NUM> to be inserted farther into the central lumen <NUM>, as shown in <FIG>. In some embodiments, a proximal end of the outer sleeve <NUM> and head <NUM> formed thereon can include a proximal-facing surface having a tapered diameter to provide a lead-in which can allow a user to insert the outer sleeve <NUM> by application of sufficient force without separately depressing the second button <NUM>. Once the outer sleeve <NUM> is inserted into the handle <NUM> sufficiently to clear the proximal head <NUM> past the pawl or second button <NUM>, it can continue until the ratchet portion <NUM> reaches the pawl. The proximal end 178p of the pawl or second button <NUM> can then be depressed to allow the outer sleeve to continue moving proximally until the pawl reaches the distal end of the ratchet portion. At this point, the distal end of the driver shaft <NUM> will be exposed beyond a distal end of the outer sleeve <NUM> and a plurality of set screws can be inserted over the distal end of the driver shaft and stacked along the drive feature <NUM>, as shown in <FIG>.

Additional details and alternate embodiments of the instrument are shown in <FIG>. <FIG>, for example, illustrates a handle <NUM> that can include a silicone over-molded grip <NUM>. Any of a variety of materials can be utilized to form the handle, including metals, polymers, etc. Grip-enhancing features such as ribs, knurling, other texturing, etc., can be provided on an outer surface of the handle.

<FIG> illustrate an embodiment wherein a handle <NUM> includes a bore formed therein to receive a pin <NUM> that can help secure a driver shaft <NUM> to the handle. As shown, the pin <NUM> can extend transversely through the handle <NUM> of the inserter instrument <NUM> and through the inner driver shaft <NUM> to prevent unwanted rotation of the driver shaft relative to the handle during use. In embodiments where the driver shaft <NUM> is threadably coupled to the handle <NUM>, undesired relative rotation between these components during use could cause separation or adjustment of relative positioning. The use of pin <NUM> disposed through coaxial transverse bores formed in the handle <NUM> and the shaft <NUM> can prevent any such relative rotation between these components.

<FIG> illustrates another embodiment of a multiple set screw insertion instrument <NUM>. The overall profile of the instrument <NUM> can be similar to an intermediate set screw driver. The inserter <NUM> can include an inner driver shaft <NUM> with a relatively long male drive feature on the distal end and a spring clip retention mechanism at the distal tip <NUM>. A number of set screws <NUM> with a female drive feature cut completely through them can be stacked on the driver along its axis. Stacking the set screws <NUM> in this way can allow the diameter of the instrument <NUM> at the distal end to remain no larger than the outer diameter OD4 of the set screw, facilitating instrument compatibility without increasing instrument profile. A ratcheting outer sleeve <NUM> can advance over the inner driver shaft <NUM>, moving the next set screw to the retention feature at the distal tip <NUM> of the driver after insertion of the previous set screw. The ratcheting feature can provide a hard stop behind the set screw which can aid a user in starting to thread into the implant. A proximal handle <NUM> can have a diameter small enough to limit the amount of torque applied by a user and can contain two buttons. A first button at the proximal end can be pressed to advance the outer sleeve <NUM> and set screws <NUM>. The second, on the side of the handle <NUM>, can be pressed to return the outer sleeve <NUM> proximally and reload the instrument. A retention mechanism on the handle can temporarily hold the outer sleeve in place when the proximal button is released to allow the ratchet mechanism to advance.

<FIG> illustrates an alternative view of the multiple set screw insertion instrument <NUM>. As noted above, the instrument <NUM> can reduce time and passes required to install several set screws when assembling a spinal fixation construct, savings that can be significant in long deformity correction cases where the construct spans several vertebral levels and includes several termination or fixation points between a rod or other spinal fixation element and implanted bone anchors. The relatively low profile cylindrical handle <NUM> can discourage the application of large amounts of torque to the set screws, and the reduced diameter distal portion can allow for set screw delivery through instrumentation, such as extension tubes coupled to the implanted bone anchors, etc..

The above-described features of the inserter are shown in <FIG> as well, including the button <NUM> on the proximal end that controls advancing the ratcheting outer sleeve <NUM> over the inner sleeve to push the loaded set screws <NUM> distally and ready a second set screw after delivery of a first set screw. Also shown is the second button <NUM> on the side of the handle <NUM> that allows for proximal movement of the outer sleeve <NUM> to reload the device with additional set screws. Finally, the figure shows a plurality of set screws <NUM> stacked over the inner shaft at the distal end of the inserter <NUM>.

<FIG> shows a partially-transparent view of the inserter <NUM> of <FIG> to illustrate its operation and internal mechanics in greater detail. Starting at the distal end of the device, the inner shaft <NUM> includes an extended distal portion having a driver tip <NUM> geometry to allow stacking multiple set screws over the tip. As shown in <FIG>, there is a spring clip <NUM> disposed at a distal end of the driver to provide soft set screw retention due to interference between the spring clip <NUM> and set screw <NUM>. At the proximal end, a spring or other bias element <NUM> urges the button <NUM> proximally to return it after a user presses the button to advance the outer sleeve <NUM>. The proximal button <NUM> interfaces with the side button <NUM> to transfer the load from the proximal button <NUM> to the outer sleeve <NUM>. A spring plunger <NUM> prevents the ratcheting outer sleeve <NUM> from following the side button <NUM> during its return stroke with the proximal button <NUM>.

<FIG> illustrate the set screw insertion process in cross-sectional views. A user first inserts the distal-most set screw into a receiver head or tulip of an implanted bone anchor. The user then rotates the inserter <NUM> to thread the set screw into the threaded portion of the bone anchor receiver head. The user then pulls the inserter proximally to separate it from the implanted set screw. The force of the user's pull and the secure threaded position of the set screw in the receiver head causes the set screw to overcome the distal spring clip and separate from the inserter, as shown in <FIG>. The user can then press the proximal button <NUM> to advance the side button <NUM> and the outer ratcheting sleeve <NUM> relative to the inner shaft <NUM> and urge the stacked set screws distally until the distal-most set screw approaches the distal end of the inserter <NUM> and stops due to interference with the spring clip, as shown in <FIG>. As the ratcheting outer sleeve <NUM> advances distally, a spring plunger <NUM> indexes from a first detent to an adjacent detent on the outer sleeve <NUM>. The spring plunger <NUM> provides enough retention force to temporarily maintain the position of the outer sleeve <NUM> when the proximal button <NUM> is released and travels with the side button <NUM> back to the initial position where they can be advanced again after delivery of another set screw, as shown in <FIG>.

<FIG> illustrate the set screw reloading process in cross-sectional views. As shown in <FIG>, the ratcheting outer sleeve <NUM> can be in a distal-most position after all set screws have been delivered. To reload, a user can press and hold down the recessed side button <NUM>, as shown in <FIG>, which can release the ratcheting outer sleeve <NUM> to move proximally when sufficient force is applied to overcome the spring plunger retention force, as shown in <FIG>. Additional set screws <NUM> can then be loaded onto the distal drive tip portion and stacked together, as shown in <FIG>. Once the recessed side button <NUM> is released, it will again interface with one of the ratchet teeth of the outer sleeve <NUM> to maintain its position and control advancement of the outer sleeve <NUM> when the proximal button is depressed.

<FIG> illustrate a cross-sectional view of another embodiment <NUM> with a side button or latch <NUM> that extends outside the handle. In particular, <FIG> illustrate the relative positions of a spring plunger/ball detent <NUM> when the outer sleeve <NUM> is in a first position and after the outer sleeve <NUM> has been advanced to deliver a new set screw.

<FIG> illustrate additional views of embodiments of a multiple set screw insertion instrument. More particularly, <FIG> illustrate various views of one embodiment of a multiple set screw insertion instrument <NUM>, including an exploded view showing outer sleeve <NUM>, inserter shaft <NUM>, handle <NUM>, dowel <NUM> for securing the inserter shaft <NUM> to the handle <NUM>, side latch <NUM>, bias spring <NUM> and pivot pin <NUM> for side latch <NUM>, proximal actuator button <NUM>, and bias spring <NUM> for actuator button.

<FIG> illustrate various views of a set screw inserter shaft <NUM>, including its distal portion with drive tip geometry <NUM> and groove <NUM> to receive a spring clip.

<FIG> illustrate various views of a set screw inserter handle <NUM>, including a lumen <NUM> to receive the inserter shaft, ratcheting outer sleeve, proximal button, and side latch components.

<FIG> illustrate various views of an actuator button <NUM>, including the proximal button surface <NUM> contacted by a user and a distally-extending portion <NUM> that interfaces with the side latch or second button <NUM>. <FIG> illustrate various detail views of the distal end of the actuator button <NUM> that interfaces with the side latch, including a cutout <NUM> with protruding flanges <NUM> having bores <NUM> formed therein that can receive the pin <NUM> to couple the side latch or second button <NUM> to the distally-extending portion <NUM>. Also shown is a recess <NUM> that can receive the bias spring <NUM> and part of the slot <NUM> that can receive the dowel <NUM> to limit the range of motion of the button <NUM> relative to the handle <NUM>.

<FIG> illustrate various views of the side latch <NUM>, including its proximal end 878p having a recess <NUM> to receive the bias spring <NUM>, its distal end 878d, and bore <NUM> that receives pin <NUM>.

<FIG> illustrate various views of the spring clip <NUM> that retains set screws on the inserter shaft by interference fit.

<FIG> illustrate various views of the outer ratcheting sleeve <NUM>, including a proximal portion with ratchet teeth <NUM> that interface with the side latch <NUM>. Note that in this embodiment the ratchet teeth <NUM> are formed over only a portion of an outer circumference of the sleeve <NUM>. In other embodiments, as disclosed above, the ratchet teeth <NUM> can be formed around an entire circumference of the outer sleeve <NUM>. Further, in some embodiments a first set of ratchet teeth or other surface features can be formed on one side of the outer sleeve and a second set of ratchet teeth or other surface features can be formed on another side of the outer sleeve, e.g., to provide different surface features to interact with each of the second button and the detent/spring plunger.

<FIG> illustrates one embodiment of a set screw <NUM> for use with the multiple set screw insertion instrument <NUM>. The set screw <NUM> can include a through-bore <NUM> formed therein with a geometry complementary to the inserter shaft distal portion <NUM> to allow the set screw to stack onto the inserter shaft <NUM> and be driven by the inserter shaft <NUM> when the inserter <NUM> is rotated. The set screw <NUM> can also include threads <NUM> formed on an outer surface thereof that can interface with threads formed on, e.g., an inner surface of a bone screw receiver head during insertion thereof using the instrument <NUM>.

The instruments disclosed herein can be constructed from any of a variety of known materials. Example materials include those which are suitable for use in surgical applications, including metals such as stainless steel, titanium, nickel, cobalt-chromium, or alloys and combinations thereof, polymers such as PEEK, ceramics, carbon fiber, and so forth.

The devices disclosed herein can be used in minimally-invasive surgery and/or open surgery. While the devices disclosed herein are generally described in the context of surgery on a human patient, it will be appreciated that the devices disclosed herein can be used in any of a variety of surgical procedures with any human or animal subject, or in non-surgical procedures.

The devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Reconditioning of a device can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly.

The devices described herein can be processed before use in a surgical procedure. First, a new or used instrument can be obtained and, if necessary, cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument can be placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and its contents can then be placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation can kill bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container can keep the instrument sterile until it is opened in the medical facility. Other forms of sterilization are also possible. This can include beta or other forms of radiation, ethylene oxide, steam, or a liquid bath (e.g., cold soak). Certain forms of sterilization may be better suited to use with different portions of the device due to the materials utilized, the presence of electrical components, etc..

Claim 1:
A surgical instrument [<NUM>], comprising:
a shaft [<NUM>] with a distal portion [<NUM>] configured to drive a set screw [<NUM>] and seat a plurality of set screws [<NUM>] stacked against one another on the shaft [<NUM>];
a handle [<NUM>] coupled to the shaft [<NUM>];
a sleeve [<NUM>] disposed over the shaft [<NUM>] and configured to contact a proximal-most set screw [<NUM>] stacked on the shaft; characterized in that:
a first button [<NUM>] disposed in the handle [<NUM>] and configured to advance the sleeve [<NUM>] distally relative to the shaft [<NUM>] by a first increment; and
a second button [<NUM>] disposed in the handle [<NUM>] and configured to permit retraction of the sleeve [<NUM>] proximally.