Patent Description:
<CIT> discloses a sternum fixation assembly for fixing the sternum following a modified median sternotomy. The sternotomy divides a median into left and right median facing walls. A pair of left and right opposing excavations are made in the walls. The assembly comprises an implantable bio-absorbable transverse member configured for enclosure into the excavations of the left and right halves of the vertically divided sternum. An elongated coupleable adjustable compression member is dimensioned for receipt about the inter-rib spaces about the sternum and adapted to apply compression to the outer ridges of the sternum to help maintain the sternum enclosure.

According to the present invention, there is provided an anchor assembly as set out in claim <NUM>.

Sternotomies are often performed on a sternum of a patient (such as prior to a cardiac procedure) by creating a midline resection and separating two halves of portions of the sternum for access to the chest cavity of the patient. Following the procedure, the sternum is often repaired using one or more wire cerclages to hold the two halves in place while the halves heal together. While wire cerclages can help to prevent medial-lateral separation (or relative movement of the halves) of the sternum, wire cerclages are less effective at limiting relative anterior-posterior movement of the halves and are also less effective at limiting relative superior-inferior movement of the halves. Wire cerclages can also unintentionally penetrate outer portions of the sternum. Rigid bone plates are a strategy often used to address the shortcomings of wire cerclages. Rigid bone plates can be secured to each portion or half of the sternum and can help to limit relative movement of the sternal halves in all directions. However, bone plate and screw assemblies can be relatively expensive as compared to wire cerclages and can add a significant number of steps to the repair procedure to properly secure the plate to the sternal halves, as <NUM> to <NUM> or more screws are often used to secure the plates.

The inventors have recognized that an anchor assembly can be used to secure the sternal halves to help limit movement of the sternal halves relative to each other while reducing costs with respect to a plate system. The anchor assembly includes an anchor insertable into a bone tunnel between the sternal halves and can include one or more cerclage elements attached to the anchor. The cerclage element(s) can be positioned around the sternal halves and locked to the anchor using a lock, such as an integral ratcheting lock (similar to those used in cable ties). Use of such an anchor assembly to repair a sternotomy can require fewer steps than that of a rigid plate assembly and screw system while use of such an anchor assembly can resist relative movement of the sternal halves better than a wire cerclage.

The above discussion is intended to provide an overview of subject matter of the present patent application. The description below is included to provide further information about the present patent application.

<FIG> illustrates an isometric view of a sternum <NUM>, sternal portions 52a and 52b, ribs 54a-54n, ribs 55a-55n, and anchor assemblies 100a and 100b. The anchor assemblies 100a and 100b each includes an anchor <NUM> and a cerclage <NUM>. The cerclage <NUM> can include cerclage elements <NUM> and <NUM>. The cerclage elements <NUM> and <NUM> are connected to the anchor <NUM> and extend outward from the body. <FIG> also shows orientation indicators Superior, Inferior, Medial, and Lateral.

During a sternotomy, one or more bone tunnel <NUM> (58a-58c) can be made at the midline <NUM> of the sternum <NUM> either before or after the midline cut is performed. In some examples, a cut guide can be used to create the midline cut or the bone tunnels <NUM>. After creation of the bone tunnels <NUM>, the anchor <NUM> of the anchor assembly <NUM> can be inserted into the bone tunnel <NUM>. For example, the anchor <NUM> of the assembly 100A can be inserted into the bone tunnel 58c. Then, the first cerclage element <NUM> can be positioned between the ribs, such as the ribs 54a and 54b and the cerclage element <NUM> can be wrapped at least partially around the sternal portion 52b of the sternum <NUM> before being secured to a lock of the assembly. Then, the cerclage element <NUM> can be positioned between the ribs such as the ribs 55a and 55b and can be wrapped at least partially around the sternal portion 52a of the sternum <NUM> before being secured to the lock.

The cerclage <NUM> can also be used to approximate the sternal portions by tightening the cerclage elements <NUM> and <NUM> and can be used to reduce the sternal portions 52a and 52b by further tightening of the cerclage elements <NUM> and <NUM> to the lock (or locks). Because bone tunnels <NUM> can be created prior to creating the midline resection, positioning of the anchor <NUM> in the bone tunnels <NUM> can help to ensure that the sternal halves 52a and 52b are properly positioned together.

Once the sternal portions 52a and 52b are aligned, the cerclage <NUM> can be tightened using the lock to fix the position of the cerclage <NUM> with respect to the sternum <NUM> and the anchor <NUM>, helping to limit movement of the sternal portions 52a and 52b relative to each other in the medial-lateral, superior-inferior, and posterior-anterior directions. The anchor assemblies <NUM> are discussed in further detail below.

<FIG> illustrates an isometric view of the anchor assembly <NUM>. <FIG> illustrates an isometric view of the anchor assembly <NUM>. <FIG> are discussed together below. The anchor assembly <NUM> can be similar to the assemblies <NUM> of <FIG>; additional details are discussed below with reference to <FIG>.

For example, <FIG> show that the cerclage elements <NUM> and <NUM> can be relatively long and can extend outward from the anchor <NUM>. The cerclage elements <NUM> and <NUM> can be different lengths. For example, the cerclage element <NUM> can be longer than the cerclage element <NUM> such that the cerclage element <NUM> to allow the cerclage element <NUM> to be used for approximation and reduction of the sternal portions (such as the portions 52a and 52b of <FIG>).

The anchor assembly <NUM> (including the anchor <NUM> and the cerclage <NUM>) can be made of materials such as metals, plastics, foams, elastomers, ceramics, composites, or combinations thereof. In some examples, anchor assembly <NUM> can be comprised of biocompatible materials such as such as stainless steels, cobalt-chromium, titanium variations, polyether ether ketone (PEEK), polyether ketone ketone (PEKK), or combinations thereof.

<FIG> also show that the cerclage <NUM> can include one or more needles <NUM>. The needle <NUM> can be connected at the end or near an outer end of the cerclage element <NUM>. The needle <NUM> can be used to more easily pass the cerclage element <NUM> through costal tissues between ribs. Following passing the cerclage element <NUM> through costal tissue, the needle <NUM> can be removed (cut off). The cerclage element <NUM> can also include a needle.

<FIG> illustrates an enlarged isometric view of the anchor assembly <NUM>. <FIG> illustrates an enlarged isometric view of the anchor assembly <NUM>. <FIG> illustrates an enlarged top view of the anchor assembly <NUM>. The anchor assembly of <FIG> can be similar to the anchor assembly <NUM> discussed in <FIG>; additional details are discussed below with reference to <FIG>.

<FIG> show that the anchor <NUM> includes a body <NUM> and a collar <NUM>. The body <NUM> can be substantially cylindrical and configured to be inserted into a bone tunnel (e.g., the bone tunnels <NUM> of <FIG>). The body <NUM> can be other shapes in other examples such as a cuboid, a hexagonal prism, octagonal prism, or the like. The collar <NUM> extends outward (such as radially outward) from an end portion 112a of the body <NUM> such that the collar <NUM> has a diameter or radially outer dimension that is larger than that of the body <NUM>. The collar <NUM> can be configured to engage a top surface of a sternum (such as the sternum <NUM>) when the body <NUM> is inserted into the bone tunnel (such as the bone tunnel <NUM>) to help limit movement of the anchor <NUM> into the bone tunnel (posteriorly). Optionally, a second collar can be connected to an end of the body <NUM> opposite the collar <NUM> that can extend radially outward therefrom. The second collar and the collar <NUM> can together capture a sternum therebetween.

The body <NUM> and the collar <NUM> (i.e., the anchor <NUM>) can be a rigid or semi-rigid body configured to engage the sternal halves without plastically deforming under loading of normal daily activities. Conversely, the cerclage <NUM> can be relatively flexible to allow the cerclage to change shapes to conform to the sternal half (or halves) around which the cerclage is positioned.

<FIG> also show that the anchor <NUM> can include channels 116a and 116b extending through the body <NUM>. and the collar <NUM>. The channels 116a and 116b can be sized to receive the cerclage elements <NUM> and <NUM>, respectively, therein or therethrough to help allow the cerclage elements <NUM> and <NUM> to lock to the anchor <NUM> to secure the sternal halves or portions. In some examples, the channels 116a and 116b can be the same size and shape in a mirrored configuration. In some examples, the channels <NUM> can be different sizes, shapes, or orientations.

<FIG> also show that the anchor <NUM> can include locks 118a and 118b, which can be optionally integrally formed into the body <NUM> of the anchor <NUM>. The locks 118a and 118b can include slots 120a and 120b, respectively, and ratchets 122a and 122b, respectively. The ratchets 122a and 122b can extend into the slots 120a and 120b, respectively, through other walls of the body <NUM> such that the ratchets 122a and 122b can extend into the channels 116a and 116b, respectively. By extending into the channels 116a and 116b, respectively, the ratchets 122a and 122b can engage the cerclage elements <NUM> and <NUM>, respectively, when the cerclage elements <NUM> and <NUM> are passed through the channels 116a and 116b, respectively, allowing the cerclage elements <NUM> and <NUM> to lock to the body <NUM>.

<FIG> also shows teeth 126a-126n of cerclage element <NUM> and teeth 128a-128n of cerclage element <NUM>. The teeth <NUM> and <NUM> can be raised portions on an underside of the cerclage elements <NUM> and <NUM>, respectively. The teeth <NUM> and <NUM> can be configured to engage the ratchets 122a and 122b, respectively to lock the cerclage elements <NUM> and <NUM> in their respective positions. Together, the teeth <NUM> and <NUM> and the ratchets 122a and 122b can form uni-directional locks, ratcheting mechanisms, or ratcheting locks, which can help to prevent the cerclage elements <NUM> and <NUM> from backing out of the locks <NUM>.

When the anchor <NUM> is implanted, the collar <NUM> can engage the outer surface (e.g., anterior surface) of the sternum to limit movement of the anchor <NUM> into the bone tunnel (e.g., bone tunnel 56a). Also, the body <NUM> can engage the bone tunnel and therefore the sternal halves 52a and 52b to help limit movement relative to each other in the interior and superior directions. When the anchor <NUM> is secured within the bone tunnel and when the cerclage <NUM> is secured to the lock <NUM> (or locks 118a and 118b), the cerclage <NUM> can help to limit separation of the sternal halves 52a and 52b, or can help to limit relative medial and lateral movement of the sternal halves 52a and 52b. Also, when the anchor <NUM> is secured within the bone tunnel and when the cerclage <NUM> is secured to the lock <NUM> (or locks 118a and 118b), the cerclage <NUM> can help to limit relative movement of the sternal halves in the anterior and posterior directions. In this way, the anchor assembly can help to limit separation or movement of the sternal halves while helping to reduce costs over other solutions.

<FIG> illustrates a top view of a sternum <NUM> and anchor assemblies 400a-400d. <FIG> illustrates a cross-sectional view across indicators 4B-4B of <FIG> of the sternum and the anchor assembly 400b. <FIG> also shows orientation indicators Superior, Inferior, Medial, and Lateral. <FIG> also shows orientation indicators Anterior, Posterior, Medial, and Lateral. <FIG> and <FIG> are discussed together below.

The anchor assemblies <NUM> can be similar to the anchor assemblies <NUM> discussed above. The anchor assembly <NUM> includes an anchor <NUM> and a cerclage <NUM> including cerclage elements <NUM> and <NUM>. The anchor <NUM> can be positionable in the bone tunnel 56b and the cerclage element <NUM> can extend around, or at least partially around, the sternal portion 52a and the cerclage element <NUM> can extend around, or at least partially around, the sternal portion 52b. The cerclage elements <NUM> and <NUM> can engage a lock <NUM> to secure the cerclage elements <NUM> and <NUM> to the sternal halves 52a and 52b, respectively. The lock <NUM> can be a ratcheting lock, such as a cable-tie type lock, or can be other lock types (e.g., fasteners, clamps, adhesives, or the like).

<FIG> shows that the anchor assembly <NUM> can include an opening <NUM> at an anterior portion of the anchor <NUM>, which can provide access to the cerclage elements <NUM> and <NUM> near the lock <NUM>. The opening <NUM> can thereby allow for the cerclage elements <NUM> and <NUM> to be trimmed near the lock <NUM>, posteriorly of the anterior surface of the anchor <NUM>, which can help to reduce palpability of the anchor assembly <NUM> and can help to limit tissue interaction between the cut ends of the cerclage <NUM> and tissues (e.g., skin).

<FIG> illustrates a top view of a sternum <NUM> and anchor assemblies 500a-500c. <FIG> illustrates a cross-sectional view across indicators 5B-5B of <FIG> of the sternum and the anchor assembly 500b. <FIG> also shows orientation indicators Superior, Inferior, Medial, and Lateral. <FIG> also shows orientation indicators Anterior, Posterior, Medial, and Lateral. <FIG> and <FIG> are discussed together below.

The anchor assemblies <NUM> can be similar to the anchor assemblies <NUM> and <NUM> discussed above in that they include an anchor. The anchor includes a body <NUM> or button that can be positionable in the bone tunnel 56b. The body <NUM> can also include slots 532a and 532b which can extend radially inward from a radially (laterally) outer surface of the body <NUM>. The slots 532a and 532b can be one slot extending around a circumference of the body <NUM> or can be individual or discreet slots. The slots <NUM> can be notches, undercuts, channels, or the like.

The slots 532a and 532b can be configured to receive the sternal halves 52a and 52b at the bone tunnel 56b, as shown in <FIG>. When the sternal halves 52a and 52b are positioned in the slots, engagement between flanges defining the slots <NUM> and between the sternal halves <NUM> can help to limit relative anterior and posterior movement of the sternal halves 52a and 52b. For example, engagement between the sternal halves 52a and 52b and the slots 532a and 532b, respectively, can help to limit anterior and posterior movement of the sternal halves 52a and 52b with respect to each other.

In examples where the slots <NUM> extend to superior and inferior portions of the body <NUM>, the slots <NUM> can also help to limit relative inferior and superior movement of the sternal portions 502a and 502b. Any of the anchor assemblies discussed above or below can be modified to include the slots of the anchor assembly <NUM>.

The assembly <NUM> also includes a cerclage <NUM> which can be a cable-tie type cerclage, as discussed in the assemblies above, or can be other types of cerclages. For example, wire can be used with the anchor assembly <NUM>, as the wire can be fed through the opening <NUM> in the body <NUM>. Similarly, a cable tie-type cerclage can be fed through the opening <NUM>. Optionally, the opening <NUM> can be capped or filled. Use of any type of cerclages can help to limit movement of the sternal halves <NUM> relative to each other in medial and lateral directions.

Optionally, a single cerclage element can be used to pass around the sternal halves 52a and 52b without passing through the opening <NUM>. In such an example, the body can help to limit movement of the sternal halves <NUM> in the anterior and posterior directions.

In use, the assemblies <NUM> can be secured to one sternal half (e.g., 52b) using the slot 532b and then the other sternal half 52a can be moved into the slots 532a to approximate the sternal atitcriorly-posteriorly, and superiorly-inferiorly. The cerclage <NUM> can then be placed to approximate medially-laterally and to secure the assemblies <NUM> in place with respect to the sternum <NUM>. Optionally, ends of the cerclage can be positioned in the opening <NUM>, which can be optionally capped. The diameter or size of the channels <NUM> can be optionally sized for creation of the bone tunnels <NUM> prior to resection of the midline <NUM>. That is, bone material may be removed during the midline <NUM> resection, changing the shape of the bone tunnels <NUM>. The channels <NUM> can be sized to accommodate the change in shape or in size of the bone tunnels <NUM>.

<FIG> illustrates a cross-sectional view of a sternum <NUM> and an anchor assembly <NUM>. <FIG> also shows orientation indicators Anterior and Posterior. The anchor assembly <NUM> can be similar to those discussed above, such as the anchor assembly <NUM>; the assembly <NUM> can differ in that the cerclage <NUM> can include a single cerclage element.

The cerclage <NUM> can be connected to the anchor <NUM>, such as at a posterior portion of the anchor <NUM>. In use, the cerclage <NUM> can be wrapped around the sternal portion 52b and then passed through an opening <NUM> of the anchor <NUM>. Optionally, the anchor <NUM> can include a first lock 618a in the opening <NUM> that can allow the cerclage <NUM> to be secured around the sternal portion 52b and then locked to the anchor <NUM>. Once the cerclage <NUM> is secured to the first lock 618a (or optionally after passing through the opening <NUM>), the cerclage <NUM> can be passed around the sternal portion 52a and can be secured to the anchor <NUM> by a second lock 618b. The second lock 618b can be in other locations in other examples.

In some examples, the anchor <NUM> and the cerclage <NUM> can be integrally formed or can be a single piece. The use of a single-piece assembly or a single cerclage element can help to simplify approximation and reduction of the two sternal halves.

<FIG> illustrates a cross-sectional view of a sternum <NUM> and an anchor assembly <NUM>. <FIG> also shows orientation indicators Anterior and Posterior. The anchor assembly <NUM> can be similar to those discussed above, such as the anchor assembly <NUM>, the assembly <NUM> can differ in that a cerclage <NUM> can include four elements, <NUM>, <NUM>, <NUM>, and <NUM>.

The cerclage elements <NUM> and <NUM> can extend from posterior portions of the anchor <NUM> such that the cerclage element <NUM> can be positioned at least partially around the sternal half 52a and the cerclage element <NUM> can extend at least partially around the cerclage half 52b. The cerclage element <NUM> can extend from an anterior portion of the anchor <NUM> around the sternal half 52a where the cerclage element <NUM> can connect to a lock 718a configured to receive the cerclage element <NUM> to secure the cerclage elements <NUM> and <NUM> around the sternal half 52a. Similarly, the cerclage element <NUM> can extend from an anterior portion of the anchor <NUM> around the sternal half 52b where the cerclage element <NUM> can connect to a lock 718b configured to receive the cerclage element <NUM> to secure the cerclage elements <NUM> and <NUM> around the sternal half 52b.

By locating the locks <NUM> outside of the anchor <NUM>, the anchor <NUM> can have a relatively smaller diameter or size, which can allow the bone tunnel <NUM> to be relatively smaller, which can help to improve patient healing. The locks <NUM> can be located anywhere along any of the cerclage elements <NUM>, <NUM>, <NUM>, and <NUM>.

<FIG> illustrates a cross-sectional view of a sternum <NUM> and an anchor assembly <NUM>. <FIG> illustrates a cross-sectional view across indicators 8B-8B of <FIG> of the sternum <NUM> and the anchor assembly <NUM>. <FIG> and <FIG> also show orientation indicators medial and lateral. <FIG> and <FIG> are discussed together below.

The anchor assembly <NUM> includes an anchor <NUM> and a cerclage <NUM>. The anchor <NUM> includes a body <NUM> and a collar <NUM>. The cerclage <NUM> can include cerclage elements, <NUM>, <NUM>, <NUM>, and <NUM> The anchor assembly <NUM> also includes locks 818a and 818b. The anchor assembly <NUM> can be similar to the anchor assemblies discussed above; anchor assembly <NUM> can differ in that it can have a body with a diamond shape. Any of the anchor assembles discussed above can be modified to include a body with a similar shape.

The body <NUM> can be shaped similar to that of a diamond from a posterior direction, as shown in <FIG>. That is, the body <NUM> can include projections <NUM> and <NUM> extending outward (e.g., laterally) from the body <NUM>, which can terminate in a point such that the projections <NUM> and <NUM> are relatively sharp. In operation, the sharp projections can engage the sternal halves 52a and 52b when the halves <NUM> are reduced to engage each other and to engage the projections <NUM> and <NUM>. Because the sternal halves have already been cut at the midline <NUM>, relatively soft bone of the sternal halves will engage the projections <NUM> and <NUM> during reduction such that the projections <NUM> and <NUM> can penetrate or deform the bone of the sternal halves 52a and 52b to create a bone tunnel for the body <NUM> in the sternal halves 52a and 52b without a drilling operation. Such a body can be thereby installed without a drilling operation, which can save time during a procedure to close a sternotomy. Optionally, the projections <NUM> and <NUM> can include multiple points or can include serrations.

<FIG> illustrates a schematic view of the method <NUM> (not claimed), in accordance with at least one example of this disclosure. The method <NUM> can be a method of repairing a sternotomy using an anchor assembly. More specific examples of the method <NUM> are discussed below. The steps or operations of the method <NUM> are illustrated in a particular order for convenience and clarity; many of the discussed operations can be performed in a different sequence or in parallel without materially impacting other operations. The method <NUM> as discussed includes operations performed by multiple different actors, devices, and/or systems. It is understood that subsets of the operations discussed in the method <NUM> can be attributable to a single actor, device, or system could be considered a separate standalone process or method.

The method <NUM> can begin with performing a sternotomy, such as making an incision and making a superior-to-inferior cut through a sternum. The method can begin or continue at step <NUM> where a bone tunnel can be created along the midline of a sternum, where the bone tunnel can be formed in a first portion of the sternum and a second portion of the sternum. For example, the bone tunnel <NUM> can be created along the midline <NUM> of the sternum <NUM>. At step <NUM>, an anchor of an anchor assembly can be positioned along the midline between the first portion of the sternum and the second portion of the sternum. For example, the anchor <NUM> can be positioned along the midline <NUM> between the first and second portions 52a and 52b.

At step <NUM>, at least a portion of the first portion of the sternum can be encircled with a cerclage of the anchor assembly, where the cerclage can be connected to the anchor and at least a portion of the second portion of the sternum can be encircled with the cerclage of the anchor. For example, the portion 52a can be at least partially encircled by the cerclage <NUM> (e.g., <NUM>, <NUM>), which can be connected to the body, and the portion 52b can be encircled by the cerclage <NUM>. At step <NUM>, the first sternum portion and the second sternum portion can be approximated using the cerclage. For example, the sternal portions 52a and 52b can be approximated using the cerclage <NUM>, such as after the cerclage <NUM> is at least partially surrounding the sternal portion 52a. Also, at step <NUM>, the first sternum portion and the second sternum portion can be reduced by tightening the cerclage in the lock. For example, the sternal portions 52a and 52b can be reduced by tightening the cerclage <NUM> in the lock <NUM>.

At step <NUM>, a lock of the anchor assembly can be engaged with the cerclage to secure the cerclage to the lock and to the anchor of the anchor and to secure the first portion of the sternum to the second portion of the sternum. For example, the lock <NUM> can be engage with the cerclage <NUM> to secure the cerclage <NUM> to the lock <NUM>.

In another example the cerclage <NUM> can be passed through the anchor <NUM> after encircling the portion of the first portion of the sternum 52a and before encircling the portion of the second portion of the sternum 52b. In another example, a cut guide can be used to perform the sternotomy along the midline <NUM> and through a center of the bone tunnel <NUM>, wherein the bone tunnel <NUM> can be formed using the cut guide. In another example, the cut guide can be used to perform the sternotomy along the midline <NUM> and through a center of the bone tunnel, where the bone tunnel <NUM> can be formed using the cut guide.

In another example, the needle <NUM> of the cerclage <NUM> can be passed through intercostal space and the needle <NUM> can be removed from the cerclage <NUM> after passing at least a portion of the cerclage <NUM> through the intercostal space.

In another example, at least the portion of the first portion 52b of the sternum can be encircled with a first element <NUM> of the cerclage <NUM> and at least a portion of the second portion 52a can be at least partially encircled by a second element <NUM> of the cerclage <NUM>, where the first element <NUM> and the second element <NUM> can be connected to the anchor <NUM>.

In another example, the lock <NUM> can include a first lock 118a can engage with the first element <NUM> of the cerclage <NUM> and can include a second lock 118b of engageable with the second element <NUM> of the cerclage. Optionally, the first lock 118a and the second lock 118b can be integrally formed with the anchor <NUM>.

Claim 1:
An anchor assembly (<NUM>) for securing a first portion and a second portion of a separated sternum (<NUM>), the anchor assembly comprising:
a lock (<NUM>);
an anchor comprising (<NUM>):
a body (<NUM>) locatable between the first portion and the second portion of the sternum, the body defining an end portion (112a); and
a collar (<NUM>) connected to the body and extending outward from the end portion of the body, the collar engageable with an outer surface of the sternum; and
a cerclage (<NUM>) connected to and extending from the anchor, the cerclage configured to at least partially surround the first portion and the second portion of the separated sternum, and the cerclage connectable to the lock to secure the cerclage and the anchor to the sternum and to secure the first portion of the separated sternum to the second portion of the separated sternum.