Patent Description:
Embodiments herein relate to a chest wall repair device, such as for use in stabilization of a sternal osteotomy or for a stabilizing a rib segment.

The sternum is a bony structure that connects ribs at the front of the chest wall. A sternotomy is a surgical procedure in which the sternum is cut along its longitudinal midline. A sternotomy is performed to gain access to the thoracic cavity for surgery on the heart, lung or other inner organs.

After a sternotomy has been performed, the divided sternum must be reconnected, or "closed," in a sufficiently stable manner to allow for bony healing of the sternotomy cut. Closure of a sternal osteotomy has traditionally been performed using stainless steel wires that are circumferentially wrapped around the sternum or through the sternum. The circumferential cerclage wires are tensioned to compress the opposing sides of the divided sternum against each other. This traditional cerclage wire technique for sternotomy closure can exhibit healing complications caused by deficient stabilization due to loose or broken wires. Especially in older patients with weaker bone, the thin steel wires can gradually cut through the sternum and loosen. Moreover, circumferential cerclage wiring is time-consuming and complicated, since it requires routing of multiple wires around the back of the sternum.

To provide a simpler and more durable fixation, metallic plates and clamps for sternal closure have been developed that attach to the front of the sternum. Clinical studies have shown that compared to traditional wire cerclage, repair of a sternal osteotomy with plates provides more stable fixation and leads to better healing, whereby patients experience less pain and require less narcotic medication.

Moreover, sternal plates and clamps generally do not require surgical access to the back of the sternum, and eliminate the application of circumferential wires or ties. However, their removal typically requires special instruments and extraction of fixation screws, whereby screw heads are frequently overgrown by soft tissue or damaged during implant insertion, complicating screw removal. The speed and ease of implant removal is critical when emergency surgical re-access is required in patients who incur a life-threatening complication. Any delay during emergent re-entry of the thoracic cavity caused by removal of a sternal plate or clamp can therefore be life-threatening, especially in case of heart failure or hemorrhagic bleeding.

In addition, other aspects of the chest wall may need to be repaired in addition to, or independent of, the sternum, such as caused by injury or other damage or by rib resection.

<CIT> describes plates for use in orthopaedic procedures. The plates have a part that is elastic between two attachment parts. Embodiments in which the elastic part and the attachment parts are separate are described. The plates can be attached to vertebrae by anchors such as bone screws.

Accordingly there is provided a chest wall repair device as detailed in claim <NUM>. Advantageous features are provided in the dependent claims.

Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings and the appended claims.

With respect to the use of any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application.

To alleviate the clinical challenges noted above, the present disclosure connects two or more plate sections by a central elastomeric portion that can readily be bisected for rapid reentry. Moreover, the invention may also be practiced for fixation of rib fractures or for spanning of rib defects or resections, whereby the central elastomeric portion enables fitting adjacent plate sections to the trajectory of the curved ribs. This elastic connection can furthermore shield the adjacent plate sections from stress and fatigue by allowing elastic flexion.

In embodiments, the present disclosure addresses the critical need for fast and simple reentry of the chest cavity by provision of a sternal plate with an elastomeric mid-section. This mid-section can readily be cut with the same scalpel used for skin incision. Assuming the sternum has not fully healed after an osteotomy, cutting of the elastomeric mid-section instantly enables separation of the osteotomized sternum and permits emergency access to the thoracic cavity without requiring special instruments.

According to the present invention, a chest wall repair device for repair of a sternum after sternal osteotomy that allows for rapid resection is provided. Embodiments herein employ a novel technique where a central portion of the device is comprised of an elastomer to allow for rapid resection using a standard surgical scalpel should there be a need to quickly re-enter the chest cavity. Previous attempts have employed strategies such as removable metallic locking pins or thin struts or wires that could be cut to allow for rapid re-entry. Others have used multi-component clamps or polymer ties to achieve removable fixation. However, these methods create additional complexity and require additional instrumentation for resection.

While embodiments herein may use the term "central" to describe the location of the elastomer, it should be understood that the term does not necessarily mean that the elastomer is at or along one or more center lines of the device. Rather, the term "central" refers to an arrangement whereby elastomer is at least partially flanked by the supporting plate sections.

Embodiments herein utilize a plate design that is comprised of a plurality of bone fixation sections that are intended to be fixed to the sternum or a rib section and joined by an elastomer section. The bone fixation sections are affixed to bone by threaded fixation members or by geometric constraint such as a hook. The elastomer section is intended to provide a pathway by which a surgeon can cut the plate to separate portions of the plate in order to access and re-open the chest cavity, should the need arise. In embodiments, the presence of elastomer may also provide a degree of flexibility regarding the angle or orientation of the fixation construct on the bone.

In some embodiments the bone fixation sections may have a feature to engage a spreading instrument to pre-stretch the elastomeric section by increasing the distance between the two bone fixation sections prior to insertion of the threaded fixation members. By pre-stretching the elastomeric section during fixation, compression can be achieved between the sternum or other bone halves after release of the instrument.

The width of the elastomer section and the elastic modulus of the elastomer material can be varied to affect the amount of motion between the two plate sections. In some embodiments, the elastomer section may be comprised of multiple elastomer materials or grades to achieve different mechanical properties in different regions. Suitable materials for the elastomeric section/portion include silicone or thermoplastic elastomers such as polyurethanes. Should it be desirable to visualize the elastomeric material on the chest x-rays, a radiopaque powder can be added to the elastomer during molding or radiopaque markers such as spheres can be inserted into the elastomer during manufacture. A suitable elastomeric material may have a modulus between <NUM>-<NUM> MPa. The elastomeric section should be similar in thickness to the plate, which is typically between <NUM>-<NUM> in thickness. The elastomeric section should be between <NUM>-<NUM> wide to allow for easy insertion of a scalpel.

In various embodiments, there are two bone fixation sections each with a plurality of receiving holes. In other embodiments, there may be multiple fixation sections each with a single or plurality of receiving holes.

In various embodiments, the bone fixation sections are comprised of a metallic biocompatible material such as titanium or stainless steel, but may also be comprised of a polymeric material such as PEEK (polyetheretherketone). In various embodiments, the bone fixation sections may be affixed to only the sternum or to both the ribs as well as the sternum to achieve greater fixation. When used, rib fixation may be on only one side, or may be on both sides of the sternum.

In various embodiments, the elastomeric section is adhered/secured to the bone fixation sections to form a single piece (unitary) device. Adhesion can be achieved during the molding process by mechanical interlocking of the elastomeric material around features on the surface of the metal parts or chemical adhesion to the surface of the metallic parts. In some cases, a primer can be applied to the metal parts to provide a more chemically favorable surface for bonding of the elastomeric material.

In various embodiments, features may be provided that restrain the maximal extension of the elastomer or serve to prevent the plate segments from gross separation thus providing a redundancy safety feature in case the elastomer should fail. In embodiments, a central elastomeric portion may contain a connection between the plate sections comprised of one or more elongated polymeric fibers. In other embodiments, at least one plate section may have an extending feature or hook, such as locking bar <NUM> in <FIG>) that selectively, mechanically interlocks within the opposing plate section and constrains the lateral motion or separation of the plate sections.

In embodiments, a central elastomeric portion may incorporate voids/spaces (such as void <NUM> in <FIG>) at the elastomer/plate interface that act to prevent propagation of delamination of the elastomer from the plate.

The sternal repair device <NUM> shown in <FIG> is comprised of left and right plate sections <NUM>, <NUM> intended to be affixed to a sternum on opposing sides of a sternal osteotomy. Each plate section incorporates multiple receiving holes <NUM> for threaded fixation members, with the two plate sections joined by a central elastomer portion <NUM> that is coupled to both plate sections to form a unitary device. Although not shown in the illustrated embodiment, the receiving holes may be threaded in order to engage threads along a portion of the threaded fixation member, such as a bone screw. A feature of this embodiment is that the central elastomer portion comprises a path by which a surgeon can rapidly bisect the sternal repair device using a scalpel should re-resection of the sternum be necessary.

<FIG> shows a cross-sectional view of device <NUM>, where the elastomer <NUM> is located between and bonded to the plate sections <NUM>, <NUM> at two interfaces <NUM>, which would prevent substantial contact between the plate sections.

<FIG> shows an anterior view of the chest wall and illustrates a suitable placement of a pair of the sternal repair devices <NUM> on the sternum <NUM> as well as an anticipated sternal resection line <NUM>. The device is intended to be placed on the sternum after an osteotomy and fixed to the sternum using threaded fixation members, such as bone screws. In some cases, multiple plates be used to fully secure the sternum, and/or they can be used in conjunction with other fixation devices.

<FIG> shows a perspective view of an alternate embodiment where the sternal repair device <NUM> comprises a plurality of plate sections <NUM> that incorporate receiving holes <NUM> for threaded fixation members joined by a central elastomer portion <NUM> that is coupled to the plate sections. <FIG> shows an exploded view where the individual plate sections <NUM> are shown separated from the elastomer portion <NUM>. The plurality of plate sections allow the device to better conform to the topography of the sternum as there is flexibility about both the longitudinal and lateral axes of the device. In this embodiment, the elastomer still comprises a path by which a surgeon can rapidly bisect the device using a scalpel should re-resection of the sternum be necessary.

<FIG> shows a perspective view of an alternate embodiment of the sternal repair device <NUM> that is comprised of two plate sections <NUM>, <NUM> that have receiving holes <NUM> for threaded fixation members joined by a central elastomer portion <NUM> that is coupled to both plate sections. Plate section <NUM> has a plurality of hooks <NUM> that are intended to engage the edge of the sternum between the ribs to provide additional stability to the device fixation or which can be used in lieu of threaded fixation members on that side of the sternal resection. <FIG> is a cross-sectional profile view of sternal repair device <NUM> illustrating hooks <NUM> on plate section <NUM>. <FIG> shows an anterior view of the chest wall illustrating placement of a pair of hooked sternal repair devices <NUM> on the sternum <NUM> as well as an anticipated sternal resection line <NUM>. While <FIG> show devices with two or three hooks, any suitable number of hooks may be used, whether <NUM>, <NUM>, <NUM>, <NUM>, or more as appropriate for the particular application.

<FIG> is a front view of an alternate embodiment of a sternal fixation device <NUM> similar to the embodiment described in <FIG> but where the plate sections <NUM>, <NUM> extend to couple with the sternum <NUM> and the rib portion <NUM> (see <FIG>) with receiving holes <NUM> for threaded fixation members present along the sternal plate and the extension <NUM>. <FIG> shows an anterior view of the chest wall illustrating placement of a sternal repair device <NUM> on the sternum <NUM> along an anticipated sternal resection line <NUM> with plate extensions <NUM> that are fixed to the ribs <NUM>.

<FIG> shows a view of the sternal fixation device <NUM> with elastomeric section <NUM> and threaded fasteners <NUM> to engage the threaded holes <NUM> in the plate sections. <FIG> shows sternal fixation device <NUM> with the threaded fasteners <NUM> fully seated in the plate sections. The sternal fixation device <NUM> is intended to be placed on the sternum with the elastomeric section <NUM> spanning the sternotomy line, and the threaded fixation members <NUM> are advanced into the holes in the plate sections <NUM> to rigidly fix the plate to the two halves of the sternum. The threaded fixation members shown are intended to be inserted after a hole is pre-drilled into the sternum, but other embodiments may include self-drilling features. If emergency re-entry is required, the surgeon may use a standard surgical scalpel to bisect the elastomer section <NUM> between the plate sections without the need for additional instrumentation.

<FIG> illustrate examples of various embodiments of chest wall repair devices for fixing the sternum and/or a rib segment. <FIG> illustrates a sterno-costal fixation device, <FIG> illustrates a longitudinal fixation device, <FIG> illustrates a transverse fixation device, and <FIG> illustrates a rib fixation / spanning device. <FIG> also shows the flexibility of the rib segment portion, as evidenced by the background gray elements showing alternative configurations.

Claim 1:
A chest wall repair device (<NUM>, <NUM>, <NUM>) comprising:
two or more plate sections (<NUM>, <NUM>, <NUM>. <NUM>) with at least a portion of one plate section configured to be affixed to a sternum or rib segment, and at least a portion of another plate section configured to be affixed to a sternum or rib segment on an opposing side of a sternal osteotomy, the plate sections having one or more receiving holes (<NUM>, <NUM>, <NUM>, <NUM>) for receiving fixation members, the plate sections having a first surface, a second surface, and a flanking surface extending between the first and second surfaces; and
a central elastomeric portion (<NUM>, <NUM>, <NUM>,) adhered to the two or more plate sections along the respective flanking surfaces, wherein the two or more plate sections are coupled together by the central elastomeric portion,
wherein the first surface of each plate section includes a bevelled edge sloping towards the respective second surface, and the central elastomeric portion (<NUM>, <NUM>, <NUM>) is adhered to the flanking surface and the bevelled edge of each plate section.