Patent Description:
With spinal stenosis, the spinal canal narrows and pinches the spinal cord and nerves, causing pain in the back and legs. Typically, with age, a person's ligaments may thicken, intervertebral discs may deteriorate, or facet joints may break down. The conditions can contribute to the narrowing of the spinal canal. Injury, heredity, arthritis, changes in blood flow, and other causes may also contribute to spinal stenosis.

Various treatments of the spine have been proposed or used including medications, surgical techniques, and implantable devices that alleviate and substantially reduce pain associated with the back. In one surgical technique, a spacer is implanted between adjacent spinous processes of a patient's spine. The implanted spacer opens the spinal canal, maintains the desired distance between vertebral body segments, and, as a result, avoids or reduces impingement of nerves and relieves pain. For suitable candidates, an implantable interspinous spacer may provide significant benefits in terms of pain relief.

Any surgery is an ordeal. However, the type of device and how it is implanted has an impact. For example, considerations when performing surgery to implant an interspinous spacer include the arrangement of the device and the possibility of damaging bone or tissue.

<CIT> discloses a percutaneous interspinous-process spacer comprising a spacer member comprising: rotatable arms configured to assume a collapsed configuration and an extended configuration; actuation means to effect transition from said collapsed configuration to said extended configuration, and vice-versa; and engaging means disposed at a proximal portion of the spacer, configured to engage said actuation means with an instrument for implanting said interspinous process spacer.

<CIT> discloses an implantable spacer for placement between adjacent spinous processes. The spacer includes a body and a wing rotatably connected to the body. The wing includes two U-shaped configurations that together define a substantially H-shaped configuration for retaining the spacer between adjacent spinous processes. An actuator assembly is connected to the body and to the wing with the proximal end of the spacer being connectable to a removable driver that is configured to engage the actuator assembly. While connected to the spacer, the driver is rotatable in one direction to deploy the wing from an undeployed to a deployed configuration and in an opposite direction to undeploy the wing. In the deployed configuration, the spacer acts as a space holder opening up the area of the spinal canal, maintaining foraminal height, reducing stress on the facet joints and relieving pain for the patient.

The present invention relates to an interspinous spacer that includes a body having a distal portion and a proximal portion; an actuator at least partially disposed in the body; and a first arm and a second arm, where the first and second arms are rotatably coupled to a distal portion of the body and coupled to the actuator, where the actuator, first arm, and second arm are configured, upon rotation of the actuator in a first direction, to move the first and second arms from an undeployed position, in which the first and second arms extend from the distal portion of the body back toward the proximal portion of the body, to a deployed position, in which the first and second arms extend away from the body.

The body includes a cup and a casing attached to the cup, wherein the actuator includes a head disposed in the cup and a shaft attached to the head and extending through the casing. In at least some aspects, each of the first arm and the second arm are configured for rotation of at least <NUM> degrees. In at least some aspects, the actuator and each of the first arm and the second arm are configured for rotation in a first direction and then rotation in a second direction opposite the first direction.

In at least some aspects, the interspinous spacer further includes an actuator retainer attached to an end of the shaft of the actuator outside of the casing. In at least some aspects, the head of the actuator includes a shaped cavity configured to receive a shaped spacer engaging bit of a driving tool for rotating the actuator. In at least some aspects, at least a portion of the shaft of the actuator includes threading. In at least some aspects, each of the first arm and the second arm includes an attachment portion with a threaded surface configured for engagement with the threading of the shaft of the actuator. In at least some aspects, each of the attachment portions further includes at least one end stop bounding the threaded surface to resist further rotation of the respective first or second arm. In at least some aspects, at least one of the threading of the shaft of the actuator or the threaded surfaces of the attachment portions of the first and second arms have a mechanical ratio of at least <NUM>:<NUM>.

In at least some aspects, the interspinous spacer further includes a first pin rotatably coupling the first arm to the body and a second pin rotatably coupling the second arm to the body. In at least some aspects, the first pin and the second pin are self-locking pins.

Another example of the disclosure is a method (does not form part of the claimed invention) of using any of the interspinous spacers. The method includes releasably coupling the interspinous spacer in the implantation position to a spacer insertion instrument; inserting the interspinous spacer coupled to the spacer insertion instrument into a patient and between a pair of adjacent spinous processes; rotating the actuator of the interspinous spacer using a driver tool to deploy the first and second arms to the deployed position with each of the arms seating a different one of the adjacent spinous processes; releasing the interspinous spacer from the spacer insertion instrument; and removing the spacer insertion instrument.

A further aspect of the disclosure is an interspinous spacer that includes a body having a distal portion and a proximal portion; an actuator at least partially disposed in the body; and a first arm and a second arm, where the first and second arms are rotatably coupled to the body and coupled to the actuator, where the actuator, first arm, and second arm are configured, upon rotation of the actuator in a first direction, to rotate the first and second arms from an implantation position, in which the first and second arms are disposed adjacent to the body along a majority of a length of each of the first and second arms, to a deployed position, in which the first and second arms extend away from the body.

In at least some aspects, the body includes a cup and a casing attached to the cup, wherein the actuator includes a head disposed in the cup and a shaft attached to the head and extending through the casing. In at least some aspects, the head of the actuator includes a shaped cavity configured to receive a shaped spacer engaging bit of a driving tool for rotating the actuator, wherein a least a portion of the shaft of the actuator includes threading. In at least some aspects, each of the first arm and the second arm includes an attachment portion with a threaded surface configured for engagement with the threading of the shaft of the actuator. In at least some aspects, at least one of the threading of the shaft of the actuator or the threaded surfaces of the attachment portions of the first and second arms have a mechanical ratio of at least <NUM>:<NUM>.

Yet another example of the disclosure is a method (does not form part of the claimed invention) of using any of the interspinous spacers. The method includes releasably coupling the interspinous spacer in the implantation position to a spacer insertion instrument; inserting the interspinous spacer coupled to the spacer insertion instrument into a patient and between a pair of adjacent spinous processes; rotating the actuator of the interspinous spacer using a driver tool to rotate the first and second arms from an implantation position, in which the first and second arms are disposed adjacent to the body along a majority of a length of each of the first and second arms, to a deployed position, in which the first and second arms extend away from the body; releasing the interspinous spacer from the spacer insertion instrument; and removing the spacer insertion instrument.

The present invention further relates to a kit that includes any of the interspinous spacers; a spacer insertion instrument configured to releasably grip the interspinous spacer for implantation into a patient; and a driver tool including a spacer engaging bit configured to engage the actuator of the interspinous spacer and rotate the actuator by rotation of the driver tool.

Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified.

The present invention is directed to the area of interspinous spacers for deployment between adjacent spinous processes.

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

Examples of interspinous spacers are found in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>. In these spacers, the arms typically extend away from the body of the spacer when the spacer is in the implantation position. In these spacers, the arms typically lead the remainder of the spacer when inserted into the body of the patient. During deployment, the arms back toward the body of the spacer and rotate away from the spinal cord to finally be disposed around the adjacent spinous processes.

In contrast, a spacer can include arms that are disposed adjacent the body and extend from the distal portion of the body of the spacer back toward the proximal portion of the body of the spacer when in the implantation position and during implantation. In at least some embodiments, the arms are disposed adjacent to the body along a majority of a length of each of the first and second arms. In at least some embodiments, an end (which may be relatively blunt) of the body of the spacer leads when the spacer is inserted into the body of the patient. In at least some embodiments, leading with a blunt end of the spacer can reduce any likelihood of cutting into bone, ligaments, or other tissue. During deployment, the arms of these spacers rotate in a direction toward the spinal cord and away from the body of the spacer to be finally disposed around the adjacent spinous processes. In at least some embodiments, rotating the arms toward the spinal cord may reduce any likelihood of catching the arms on the spinous processes prior to full deployment.

<FIG> illustrates one embodiment of an interspinous spacer <NUM> that includes a body <NUM>, a first (or superior) arm <NUM>, a second (or inferior) arm <NUM>, and an actuator <NUM>. The body includes a distal portion 102a and a proximal portion 102b. The actuator <NUM> is at least partially disposed in the body <NUM> and extends from the distal portion 102a of the body to the proximal portion 102b of the body. The first and second arms <NUM>, <NUM> are coupled to the distal portion 102a of the body <NUM> and coupled to the actuator <NUM> for rotation of the arms as described below.

In <FIG>, the spacer <NUM> is in the implantation position (e.g., undeployed position) with the arms <NUM>, <NUM> extending from the distal portion 102a of the body back toward the proximal portion 102b of the body and disposed adjacent to the body <NUM> along at least a majority of the length of the arms, instead of extending away from the body. In <FIG>, the arms <NUM>, <NUM> of the spacer <NUM> are partially deployed and in <FIG> the arms <NUM>, <NUM> are in the deployed position with the arms <NUM>, <NUM> extending away from the body <NUM>. <FIG> is a top view of the spacer, <FIG> is a cross-sectional view of at least a portion of the spacer <NUM>, and <FIG> is an exploded view of the spacer <NUM>.

Turning to <FIG>, the actuator <NUM> includes a head <NUM>, a shaft <NUM> with threads <NUM> extending along a least a portion of the shaft, and a collar <NUM> (<FIG>) and flange <NUM> (<FIG>) disposed at an end of the actuator opposite the head. The head <NUM> of the actuator <NUM> includes a shaped cavity <NUM> to receive a driver tool <NUM> (<FIG>) with a complementary shaped spacer engaging bit <NUM>. The head <NUM> of the actuator <NUM> is disposed in a cup <NUM> of the body <NUM> of the spacer <NUM> and the shaft <NUM> of the actuator extends into a cavity <NUM> defined by a casing <NUM> of the body <NUM>. An actuator retainer <NUM> is coupled to the collar <NUM> of the actuator <NUM> between the flange <NUM> of the actuator and an outer surface of the casing <NUM> for retention of the remainder of the actuator in the body <NUM> of the spacer <NUM>.

The cup <NUM> is coupled to a proximal end of the casing <NUM>. In at least some embodiments, the cup <NUM> and casing <NUM> are formed together by, for example, molding. In other embodiments, the cup <NUM> is attached to the casing <NUM> by welding or any other suitable attachment technique. In at least some embodiments, the body <NUM> includes undercut notches <NUM> formed on opposite sides of the cup <NUM>. In at least some embodiments, the notches <NUM> are configured for attachment of clamps <NUM> of a spacer insertion instrument <NUM>, as described in below with respect to <FIG>.

Pins <NUM> extend through pin openings <NUM> in the casing <NUM> of the body <NUM> and attach the arms <NUM>, <NUM> to the casing. In at least some embodiments, the pins <NUM> are self-locking pins. Utilizing self-locking pins <NUM> and a can reduce the need for welding components of the spacer <NUM>.

Each arm <NUM>, <NUM> includes an attachment portion <NUM> with a tubular opening <NUM> for receiving one of the pins <NUM>. Each of the attachment portions <NUM> extends into the casing <NUM> through an arm opening <NUM> in the casing so that each of the arms <NUM>, <NUM> is rotatably coupled to the body <NUM> by one of the pins <NUM>.

The arm <NUM> includes two extensions 104a, 104b coupled by a bridge <NUM> from which the attachment portion <NUM> extends. The arm <NUM> includes two extensions 106a, 106b coupled by a bridge <NUM> from which the attachment portion <NUM> extends. In the implantation position (see, <FIG>), the extensions 104a, 104b, 106a, 106b extend adjacent the body <NUM> and back toward the cup <NUM> of the body and, at least in some embodiments, a portion of the extensions 104a, 104b, 106a, 106b extends beyond the cup <NUM> of the body <NUM> as illustrated in <FIG>. In at least some embodiments, in the implantation position, a portion of the body <NUM> is disposed between extensions 104a, 104b and between extensions 106a, 106b. In at least some embodiments, in the implantation position, at least a portion of the bridges <NUM>, <NUM> are disposed beneath ledges <NUM> formed by the casing <NUM> and cutouts <NUM> in the casing (see, <FIG> for an example of one embodiment of the spacer in the implantation position. ) When the arms <NUM>, <NUM> are deployed, as illustrated in <FIG>, the pairs of extensions 104a, 140b, 106a, 106b extend away from the body <NUM> of the spacer <NUM> with the extensions of each pair disposed on opposing sides of one of the adjacent spinous processes.

Each of the attachment portions <NUM> of the arms <NUM>, <NUM> includes a threaded surface <NUM> that engages (see, <FIG>) the threads <NUM> on the shaft <NUM> of the actuator <NUM>. The threads <NUM> on the shaft <NUM> of the actuator <NUM> act as a track for movement of the arms <NUM>, <NUM> between the implantation position (<FIG>) and the deployed position (<FIG>). As the actuator <NUM> is rotated in a first direction (for example, clockwise), the arms <NUM>, <NUM> deploy from the implantation position (see, <FIG>) to the deployed position (see, <FIG>). In at least some embodiments, as the actuator <NUM> is rotated in a second direction (for example, counterclockwise), the arms <NUM>, <NUM> retract back toward the implantation position. In at least some embodiments, during deployment the arms <NUM>, <NUM> synchronously deploy opposite each other. During deployment, the arms <NUM>, <NUM> rotate dorsally and, at least in some embodiments, can cut or dissect tissue from the dorsal direction. In at least some embodiments, the dorsal deployment of the arms <NUM>, <NUM> of the spacer <NUM> may be advantageous over the ventral deployment of arms of known spacers. In at least some embodiments, the deployment load is primarily applied by the head <NUM> of the actuator <NUM> acting against the cup <NUM> of the body <NUM>.

In at least some embodiments, during deployment, the arms <NUM>, <NUM> rotate through an arc of approximately <NUM> degrees with respect to the body <NUM> to the deployed position in which the extensions 104a, 104b, 106a, 106b of the arms are approximately perpendicular to the longitudinal axis of the body <NUM> as shown in <FIG>. In at least some embodiments, the arms <NUM>, <NUM> have a U-shaped projection in a plane perpendicular to the longitudinal axis of the body <NUM>.

In at least some embodiments, the threaded surface <NUM> on the attachment portions <NUM> of each of the arms <NUM>, <NUM> is bounded by one or more end stops 131a, 131b (<FIG>) that preclude further rotation of the arms <NUM>, <NUM>. In at least some embodiments, the threaded surface <NUM> on the attachment portions <NUM> of each of the arms <NUM>, <NUM> or the threads <NUM> on the shaft <NUM> of the actuator <NUM> (or any combination thereof) are selected to have a mechanical ratio (for example, a mechanical ratio of at least <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, or more) that resists or prevents rotation of the arms <NUM>, <NUM> by application of pressure or force against the arms. This can, for example, prevent or resist force applied to the arms by movement or the like from inadvertently rotating the arms <NUM>, <NUM> after deployment.

In at least some embodiments, the length of the bridge <NUM> of the arm <NUM> is approximately <NUM> to <NUM> millimeters and the length of the bridge <NUM> of the arm <NUM> is approximately <NUM> to <NUM> millimeters. In at least some embodiments, the tip-to-tip distance of the extensions 104a, 104b is approximately <NUM> to <NUM> millimeters and the tip-to-tip distance of the extensions 106a, 106b is approximately <NUM> to <NUM> millimeters. In at least some embodiments, the arm <NUM> forms a larger space for receiving the superior spinous process than the space formed by the arm <NUM> for receiving the inferior spinous processes as spinous processes are naturally narrower on top and wider on the bottom.

<CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT> illustrate a variety of tools for insertion and deployment of a spacer between adjacent spinous processes. These tools can be used or modified for insertion and deployment of the spacer <NUM> described above.

As an example, <FIG> and <FIG> illustrate a spacer insertion instrument <NUM> and a driver tool <NUM>, respectively. The spacer insertion instrument <NUM> includes a cannula <NUM> connected to a handle <NUM>. The spacer insertion instrument <NUM> defines a central passageway <NUM> through the handle <NUM> and cannula <NUM>. The driver tool <NUM> is removably insertable into the central passageway <NUM>.

The cannula <NUM> includes clamps (for example, prongs) <NUM> to releasably clamp to the body <NUM> of the spacer <NUM> (for example, to the undercut notches <NUM> formed on opposite sides of the cup <NUM> of the body) for delivery of the spacer into the patient using the pacer insertion instrument <NUM>. In at least some embodiments, the clamps <NUM> include extensions <NUM> that extend inwardly toward each other to form hooks. In at least some embodiments, the extensions <NUM> can engage the undercut notches <NUM> (<FIG>) formed on opposite sides of the cup <NUM> of the body <NUM> of the spacer <NUM> to grip the spacer.

The cannula <NUM> also includes an inner shaft <NUM> (to which the clamps <NUM> are attached), an outer shaft <NUM>, and a control <NUM>. In at least some embodiments, the inner shaft <NUM> is connected to the handle <NUM> and the outer shaft <NUM> is passed over the inner shaft <NUM>.

The outer shaft <NUM> translates with respect to the inner shaft <NUM> (or, alternatively, the inner shaft translates with respect to the outer shaft) using the control <NUM>. The translation of the outer shaft <NUM> (or the inner shaft <NUM>) operates the clamps <NUM>. When the outer shaft <NUM> moves away from the clamps <NUM>, the clamps separate to allow loading (or unloading) of the spacer <NUM> on the spacer insertion instrument <NUM>. When the outer shaft <NUM> moves toward the clamps <NUM>, the clamps are moved together to grip the spacer <NUM>. For example, the clamps <NUM> can grip the undercut notches <NUM> formed on opposite sides of the cup <NUM> of the body <NUM> of the spacer <NUM>. In this manner, the spacer insertion instrument <NUM> can hold the spacer <NUM> for delivery of the spacer into position between adjacent spinous processes within the patient.

Turning to <FIG>, a driver tool <NUM> includes a handle <NUM> at the proximal end and a spacer engaging bit <NUM> at the distal end. The handle <NUM> and spacer engaging bit <NUM> are connected by a shaft <NUM>. The driver tool <NUM> is sized to be inserted into the central passageway <NUM> of the spacer insertion instrument <NUM> such that the spacer engaging bit <NUM> at the distal end operatively connects with a spacer <NUM> gripped by the clamps <NUM> of the spacer insertion instrument <NUM>. The spacer engaging bit <NUM> includes features for engaging with the shaped cavity <NUM> (see, <FIG>) in the head <NUM> of the actuator <NUM> of the spacer <NUM>. In at least some embodiments, the driver tool <NUM> has a spacer engaging bit <NUM> that is complementary to the shaped cavity <NUM> in the head <NUM> of the actuator <NUM> of the spacer <NUM>. Rotating the driver tool <NUM> when engaged with the head <NUM> of the spacer <NUM> rotates the actuator <NUM> to deploy the arms <NUM>, <NUM> of the spacer (or, in at least some embodiments, return the arms to the implantation position if rotated in the opposite direction.

In at least some embodiments, a small midline or lateral-to-midline incision is made in the patient for percutaneous delivery of the spacer <NUM>. In at least some embodiments, the supraspinous ligament is avoided. In at least some embodiments, the supraspinous ligament is split longitudinally along the direction of the tissue fibers to create an opening for the instrument. In at least some embodiments, one or more dilators may be used to create or enlarge the opening.

In at least some embodiments, the spacer <NUM>, in the implantation state (see, <FIG>), is releasably attached to the spacer insertion instrument <NUM> as described above. In at least some embodiments, the spacer <NUM> is inserted into a port or cannula, if one is employed, which has been operatively positioned to form an opening to the interspinous space within a patient's back. The spacer <NUM>, attached to the spacer insertion instrument <NUM>, is inserted into the interspinous space between the spinous processes of two adjacent vertebral bodies. In at least some embodiments, the spacer <NUM> is advanced beyond the end of a cannula or, alternatively, the cannula is pulled proximately to uncover the spacer <NUM> connected to the spacer insertion instrument <NUM>. Once in position, the driver tool <NUM> is inserted into the spacer insertion instrument <NUM>, if not previously inserted, to engage the actuator <NUM>. The driver tool <NUM> is rotated to rotate the actuator <NUM>. The rotating actuator <NUM> begins deployment of the arms <NUM>, <NUM> of the spacer <NUM>. Rotation in one direction, for example, clockwise, for example, deploys the arms <NUM>, <NUM> through a partially deployed position (see, <FIG>) to the deployed position (see, <FIG>).

Other than the implantation position or deployed position, the arms <NUM>, <NUM> of the spacer may be positioned in one of many partially deployed positions or intermediary positions. In at least some, embodiments, the deployment of the arms <NUM>, <NUM> can be reversed by rotating the actuator <NUM> in the opposite direction, for example, counterclockwise.

In at least some embodiments, a clinician can observe with fluoroscopy or other imaging technique the positioning of the spacer <NUM> inside the patient and then choose to reposition the spacer <NUM> if desired. Repositioning of the spacer may involve reversing, or partially reversing, the deployment of the arms <NUM>, <NUM>. The arms <NUM>, <NUM> of the spacer <NUM> may then be re-deployed into the desired location. This process can be repeated as necessary until the clinician has achieved the desired positioning of the spacer in the patient.

Claim 1:
An interspinous spacer (<NUM>), comprising:
a body (<NUM>) having a distal portion (102a) and a proximal portion (102b), wherein the body comprises a cup (<NUM>) and a casing (<NUM>) attached to the cup;
an actuator (<NUM>) at least partially disposed in the body, wherein the actuator comprises a head (<NUM>) disposed in the cup and a shaft (<NUM>) attached to the head and extending through the casing; and
a first arm (<NUM>) and a second arm (<NUM>), wherein the first and second arms are rotatably coupled to a distal portion of the body and coupled to the actuator, wherein the actuator, first arm, and second arm are configured, upon rotation of the actuator in a first direction, to move the first and second arms from an undeployed position, in which the first and second arms extend from the distal portion of the body back toward the proximal portion of the body, to a deployed position, in which the first and second arms extend away from the body.