Patent Description:
The spine of a person provides body structure and support, while allowing the person to move about freely and to bend with flexibility. The building blocks of the spine are the vertebrae. Between two adjacent vertebrae lies an intervertebral disc, which functions as a shock absorber, allows movement of the vertebrae and acts as a ligament to hold the vertebrae together. An intervertebral disc consists of an outer fibrous ring, the annulus fibrosus, which surrounds an inner gel-like centre, the nucleus pulposus. The posterior longitudinal ligament lies just posteriorly to the annulus fibrosus, covering the posterior surface of the spine vertebrae along with the associated discs.

An excessive strain or trauma to the spine may cause a crack, tear or rupture (defect) of the annulus fibrosus, through which a fragment of the nucleus pulposus can protrude into the spinal canal. This situation is called disc herniation and may result in a compression of the surrounding spinal nerves, what in turn causes pain and in many cases neurological complications to the person.

Two of the existing solutions for the treatment of a herniated disc are spinal fusion and artificial disc replacement. During spinal fusion, a direct connection between the vertebrae surrounding the herniated intervertebral disc is formed. Due the fixation of the vertebrae, the motion of the intervertebral disc is prevented and thus pain relief is achieved. However, this approach severely limits the motion of the affected part of the vertebral column. During artificial disc replacement, the herniated intervertebral disc is removed and replaced by a prosthetic implant, i.e. an artificial disc. However, disc replacement can only treat limited types of disc pathology.

Another solution for the treatment of disc herniation is microdiscectomy spine surgery, which aims to relieve pressure on a spinal nerve root by removing the intervertebral disc material that is responsible for it. The problem with this type of surgery is that, following the removal of the intervertebral disc material, a defect (through which the removal was performed) remains in the annulus fibrosus. This defect serves as a pathway for additional intervertebral disc material to protrude into the spinal canal, resulting in the recurrence of the herniation. Since thousands of patients each year require surgery to treat disc herniation and approximately five percent of these patients will suffer recurrent disc herniation condition, with substantial implications in terms of the cost of medical treatment and human suffering, an effective solution to this problem is needed.

<CIT> discloses a patch for preventing a recurrence of lumbar disc hernia. In particular, the patch is intended to securely cover the gap formed at the posterior longitudinal ligament and annulus fibrosus during microdiscectomy.

<CIT> discloses a further example of methods and implantable medical devices, such as "annulus stents" for the closure, sealing and/or repair of an aperture in the intervertebral disc annulus.

<CIT> discloses orthopedic implants made from a mesh material. The mesh material can be treated in order to promote bone growth, to provide antibiotics, or to provide other beneficial treatment. Specific applications for the implants include, for example, a prosthetic ligament, a tension band, an interbody device, or a fixation device that extends across one or more joints or fractures.

<CIT> discloses a repair system for a compromised or herniated spine disc. The repair system includes a spine disc patch to cover the herniation, and hooks, fasteners or the like to attach the spine disc patch to the vertebra surrounding the compromised disc. The repair system also includes an application tool to introduce and deploy the spine disc patch and spine disc patch fasteners to and on the disc herniation site. The spine disc patch is composed of a mesh, screen or the like of a biocompatible material with a perimeter, edge or side portion formed of a resilient biocompatible material. The mesh is preferably, but not necessarily, formed of a flexible but non-resilient biocompatible material. The perimeter is preferably, but not necessarily, formed of a flexible, resilient biocompatible material. In this manner, the spine disc patch may fold, bend, crumple or otherwise be deformed for introduction to the disc herniation site within an application tool, then unfold, expand, spread out, unfurl or otherwise open up at and over the disc herniation site when released from the application tool. The application tool consists of an elongate tube connected to a fixed portion of a handle with a rod, disposed for axial movement within the elongate tube. The rod is connected to a pivoting portion of the handle such that the rod axially moves within the elongate tube when the pivoting portion of the handle is moved.

<CIT> discloses a spine stabilization system including a flexible member attachable to a portion of the spinal column. The member includes components that are oriented and function similar to the natural anterior longitudinal ligament and annulus fibers respectively. The components resist loading applied by extension and rotation of the spine, while the flexibility of the member does not subject it to the compressive loading of the spinal column segment to which it is attached.

<CIT> discloses a spinal implant and method of implant use for application about a spinal implant area. The spinal implant is formed of a resilient and/or elastic covering, and first and second bone fasteners for holding the covering in place. An all-in-one deployment instrument is also provided that delivers and installs the spinal implant to the spinal implant site. The spinal implant provides a covering for the spinal implant site such as a spinal disc fissure, about a portion of a spinal disc after a full or partial discectomy or other procedure, and/or over any spinal disc area. The covering is disposed between and held by the first and second bone fasteners. An application instrument for introducing and installing the present spinal implant is also provided. The instrument introduces then applies the covering at the spinal implant site and drives the vertebral body staples into the vertebral body to secure the covering to the spinal implant site. The covering may include a spinal medicament and/or provide a spinal medicament delivery system.

It is an object underlying the present invention to provide an improved patch for covering a defect in the annulus fibrosus of an intervertebral disc, and in particular also in the posterior longitudinal ligament, of a spine of a patient.

The invention is defined by the subject matter of the independent claim.

A patch for covering a defect in the annulus fibrosus of an intervertebral disc, and in particular also in the posterior longitudinal ligament, of a spine is disclosed. The patch comprises a patch body formed as a sheet.

The patch body preferably has a tensile stiffness between <NUM> N/m (<NUM> N/mm) and <NUM> N/m (<NUM> N/mm), more preferably between <NUM> N/m (<NUM> N/mm) and <NUM> N/m (<NUM> N/mm), parallel to a first axis. The first axis lies on a main face of the patch body (sheet).

Due to the chosen tensile stiffness and the design of the patch body as a sheet, the patch is configured to cover the defect in the annulus fibrosus and thereby prevent the nucleus pulposus from exiting therethrough without compromising the kinematics of the spine, as the patch is able to elastically deform during movement of the spine. In other words, the proposed patch is flexible, wherein its flexibility is chosen such that the patch does not restrict spinal movement of the patient in its fixed state to the spine. Thus, in particular contrary to the already known solution presented above, the proposed patch does not alter the mechanics of the vertebrae, in particular it does not fix the vertebrae, to which it is attached. Thus, for example when a.

patient bends forward, i.e. when the patient flexes his/her spine, the patch can adapt to the movement of the spine and extend parallel to the first axis of the patch body.

The patch body preferably has a tensile stiffness between <NUM> N/m (<NUM> N/mm) and <NUM> N/m (<NUM> N/mm), more preferably between <NUM> N/m (<NUM> N/mm) and <NUM> N/m (<NUM> N/mm), parallel to a second axis. The second axis lies on the main face of the patch body (sheet). The first axis and the second axis are perpendicular to each other.

Preferably, the first axis is more particularly substantially parallel to the longitudinal axis of the human body, when the patch is attached to the spine of the human body. In other words, the first axis preferably extends substantially parallel to a longitudinal axis of at least a part of the spine. As far as the second axis is concerned, the second axis is more particularly substantially parallel to the mediolateral axis of the human body, when the patch is attached to the spine of a human. The term "substantially" is used here to consider the fact that the spine of a person has a natural curvature.

Further, the first axis can preferably lie on a first symmetry plane of the patch body. Similarly, the second axis can preferably lie on a second symmetry plane of the patch body. In other words, the first axis may preferably a first symmetry axis of the main face of the patch body, while the second axis may preferably be a second symmetry axis of the main face of the patch body.

It is noted that the main face of a sheet is more particularly the face of the sheet that has the largest surface area.

Within the framework of the present invention, a sheet is in particular defined as an element with a thickness that is much smaller than any other dimension suitable for defining the sheet. For example, in the case of a sheet that has the shape of a parallelogram, the thickness of the sheet is much smaller than the other two dimensions, i.e. the length and the width, of the sheet. Here, the main face of the sheet is the face defined by the width and length of the sheet. In the case of a circular sheet, the thickness of the sheet is much smaller than the diameter of the circular sheet. Here, the main face has a circular shape.

The expression "much smaller" particularly means within the scope of the present invention "at least three times smaller", preferably "at least four times smaller", more preferably "at least five times smaller".

Preferably, the patch body has a total tensile elongation (percent elongation) equal to or higher than <NUM>% parallel to the first axis and/or parallel to the second axis. In other words, the total tensile elongation the patch body can undergo is equal or higher to <NUM>% parallel to the first axis and/or parallel to the second axis.

Preferably, a tensile load of equal to or less than <NUM> N, more preferably a tensile load of equal to or less than <NUM> N, parallel to the first axis and/or parallel to the second axis is required for achieving a tensile elongation (percent elongation) of equal to or higher than <NUM>% parallel to the first axis and/or parallel to the second axis, respectively. This configuration of the patch enables its elastic deformation under loads that are expected for a whole range of motion of the spine. Thus, the elastic deformation of the patch can match the displacement of the vertebrae, to which the patch may be attached, for the whole range of motion of the spine.

Within the scope of the present invention, the total tensile elongation of the patch body parallel to the direction of the first axis or the second axis is in particular the elongation percentage of the patch when one end of the patch body (sheet) is fixed and the other end of the patch body (sheet) is subjected to a tensile load parallel to the first or the second axis, respectively, and a failure of the patch occurs.

Preferably, the patch body has the same aforementioned mechanical properties on a plane parallel to a main face (of the patch body), in particular in the direction of every axis that lies on the main face.

Preferably, the patch body is made of a material that has a yield strength between <NUM> x <NUM><NUM> Pa (<NUM> MPa) and <NUM> x <NUM><NUM> Pa (<NUM> MPa). The yield strength or yield stress is the stress corresponding to the yield point at which a material begins to deform plastically.

According to the invention, the patch body is formed as a mesh comprising non-woven fibres. In particular, the fibres may be randomly distributed in the mesh.

Preferably, the mesh comprises/is made of polytetrafluoroethylene fibres and/or expanded polytetrafluoroethylene fibres.

Advantageously, the patch body is impermeable to the material of the nucleus pulposus of the intervertebral disc. Most preferably, the patch body is impermeable to fluids with viscosity up to <NUM> mPa*s (milliPascal-second). This has the advantage that the material of the nucleus pulposus can be prevented from exiting the intervertebral disc in the whole range of motion of the spine.

The patch body preferably comprises at least one through opening for receiving a fastening element for fastening the patch to the spine. The at least one through opening is preferably a hole.

More preferably, the patch body comprises at least two through openings that are arranged in the direction of the first axis. Thus, the patch can be attached to the vertebrae on both sides of the intervertebral disc, i.e. the vertebrae, between which the affected intervertebral disc lies.

It is further advantageous if a reinforcing and/or stress distribution element is provided on the patch body around a boundary of the at least one through opening. Thus, on one hand, the reinforcing and/or stress distribution element acts as a protective means for the patch body around the at least one through opening, thereby reducing or eliminating the risk of tearing and/or abrasion of the patch body. On the other hand, said element may prevent a concentration of stresses around the at least one through opening by distributing stresses, e.g. caused by the fastening element, over a larger area of the patch body.

The reinforcing and/or distribution element is preferably made of metal or plastic.

Preferably, the reinforcing and/or stress distribution element is formed as an insert that is inserted in the at least one through opening. More particularly, the reinforcing and/or stress distribution element may be formed as a grommet. In particular, the grommet comprises a main body and at least one collar to be arranged on the patch body around the at least one through opening, in particularly around a boundary of the at least one through opening. The main body is inserted in the through opening. Preferably, the grommet comprises two collars, each of which is intended to be arranged on one of the main faces of the patch body.

Further, it is advantageous when the reinforcing and/or stress distribution element is fixedly connected to the patch body. The term "fixedly connected" means in particular that the reinforcing and/or stress distribution element cannot be removed from the patch body without being damaged and/or without damaging the patch body.

When the grommet comprises two collars, the collars are preferably pressed against the patch body so that the grommet is fixedly connected to the patch body.

It is advantageous if every through opening of the patch body is provided with a reinforcing and/or stress distribution element.

According to an advantageous embodiment, the patch body has the shape of a parallelogram, in particular a rectangular shape. This means that the main face(s) of the patch body is/are a parallelogram, in particular of rectangular shape. The vertical cross-section of the patch body, that is perpendicularly to the first axis, is advantageously of rectangular shape. The cross-section of the patch body perpendicularly to the second axis is advantageously of rectangular shape.

Preferably, the patch body extends parallel to the first axis more than it extends parallel to the second axis.

The length of the patch body preferably lies in the range between <NUM> and <NUM>, in particular in the range between <NUM> and <NUM>.

The width of the patch body preferably lies in the range between <NUM> and <NUM>, in particular in the range between <NUM> and <NUM>.

The thickness of the patch body preferably lies in the range between <NUM> and <NUM>, more preferably between <NUM> and <NUM>.

According to an alternative advantageous embodiment of the present invention, the patch body may have a circular shape.

Preferably, the minimum distance between a boundary of the at least one through opening and a boundary of the patch body parallel to the first axis is at least <NUM>%, preferably at least <NUM>%, of the dimension of the patch body parallel to the first axis.

Similarly, the minimum distance between a boundary of the at least one through opening and a boundary of the patch body parallel to the second axis is preferably at least <NUM>%, preferably at least <NUM>%, of the dimension of the patch body parallel to the second axis.

It is understood that all the components of the patch are each made of a biocompatible material.

Further, the present invention refers to a surgical kit that comprises a patch as described above and at least one fastening element for fastening the patch body to the spine.

Further, the surgical kit may comprise at least one reinforcing and/or stress distribution element. The at least one reinforcing and/or stress distribution element can preferably be formed as the reinforcing and/or stress distribution element described above.

It is noted that all mechanical properties of or related to the patch can advantageously be measured by defining the load-displacement curve of the patch. For calculating the load displacement curve, a plurality of identical patches, in particular six identical patches, can be prepared. One end of the patch can be clamped in a vice attached to the base of a testing machine (Instron <NUM>; Instron, Norwood, MA, USA). The other end can be secured in a clamp attached to the functional column of the testing machine. Each patch can particularly be preloaded with <NUM> N for <NUM> seconds; then pulled at <NUM>/seconds to failure, with the data preferably captured at <NUM> on a computer.

Further disclosed is the use of the previously described patch in a surgical method, in particular in a surgical method for covering a defect in the annulus fibrosus of an intervertebral disc, and in particular also in the posterior longitudinal ligament, of a spine of a patient.

The formulation "for covering a defect in the annulus fibrosus of an intervertebral disc, and in particular also in the posterior longitudinal ligament, of a spine" in particular means in the context of the present invention "for covering a defect in the annulus fibrosus of an intervertebral disc of a spine or for covering a defect in the annulus fibrosus of an intervertebral disc and the posterior longitudinal ligament of a spine".

The present invention also refers to a patch for covering a defect in the annulus fibrosus of an intervertebral disc, and in particular also in the posterior longitudinal ligament, of a spine, comprising a patch body that is formed as a sheet and as a mesh made of non-woven fibres, preferably wherein the mesh comprises polytetrafluoroethylene fibres and/or expanded polytetrafluoroethylene fibres. The patch is configured to cover the defect in the annulus fibrosus and thereby prevent the nucleus pulposus from exiting therethrough without compromising the kinematics of the spine, as the patch is able to elastically deform during movement of the spine.

These and further details, advantages and features of the present invention will be described based on embodiments of the invention and by taking reference to the accompanying <FIG>.

In the following, embodiments and the technical background of the present invention are presented in detail by taking reference to the accompanying <FIG>. Identical or equivalent elements and elements which act identically or equivalently are denoted with the same reference signs. Not in each case of their occurrence a detailed description of the elements and components is repeated.

<FIG> shows a flexible patch <NUM> for covering a defect in the annulus fibrosus of an intervertebral disc, an in particular also of the posterior longitudinal ligament, of a spine of a patient according to the first embodiment of the present invention. A part of a spine <NUM> of a person represented by two vertebrae <NUM> and an intervertebral disc <NUM> is shown in <FIG>. For illustrative purposes, the posterior longitudinal ligament is not shown in the figures. When the intervertebral disc <NUM> has a defect in its annulus fibrosus <NUM>, the patch <NUM> is intended to be attached to the spine <NUM> in order to cover said defect and prevent material of the nucleus pulposus <NUM> of the intervertebral disc <NUM> from exiting through the defect. This will be further explained with reference to <FIG>.

Referring back to <FIG>, the patch <NUM> comprises a patch body <NUM> that is formed as a rectangular (flexible) sheet having a length <NUM>, a width <NUM> and a thickness <NUM>.

The fact that the patch body <NUM> is formed as a sheet means that its length <NUM> and width <NUM> are each much larger than its thickness <NUM>. In particular, the length <NUM> and the width <NUM> of the patch body <NUM> may each be at least three times larger, preferably at least four times larger, and more preferably at least five times larger than the thickness <NUM> of the patch body <NUM>. The length <NUM> of the patch body <NUM> extends in the direction of a first axis <NUM> of the patch body <NUM> and the width <NUM> in the direction of a second axis <NUM> of the patch body <NUM>.

The first axis <NUM> and the second axis <NUM> are perpendicular to each other and lie on a main face <NUM> of the patch body <NUM>. In particular, the first axis <NUM> and the second axis <NUM> lie on a first symmetry plane and a second symmetry plane of the patch body <NUM>, respectively. In other words, the first axis <NUM> is a first symmetry axis and the second axis <NUM> a second symmetry axis of the main face <NUM> of the patch body <NUM>.

It is noted that the length <NUM>, width <NUM> and thickness <NUM> of the patch body <NUM> as well as the first axis <NUM> and the second axis <NUM> refer to the patch body <NUM> when it lies flat on a surface.

The patch body <NUM> has a tensile stiffness parallel to the first axis <NUM> that lies between <NUM> x <NUM><NUM> N/m and <NUM> x <NUM><NUM> N/m, in particular between <NUM> x <NUM><NUM> N/m and <NUM> x <NUM><NUM> N/m. Further, the patch body <NUM> has a tensile stiffness parallel to the second axis <NUM> that lies between <NUM> x <NUM><NUM> N/m and <NUM> x <NUM><NUM> N/m, in particular between <NUM> x <NUM><NUM> N/m and <NUM> x <NUM><NUM> N/m. Due to this configuration, the patch <NUM> is able to deform by the forces being exerted on the vertebrae <NUM> and consequently also to the body patch <NUM> being attached to the vertebrae <NUM> during movement of the spine <NUM>. Thereby, the patch <NUM> does not limit but rather follows a movement of the vertebrae <NUM> relative to each other.

Preferably, the patch body <NUM> has a total tensile elongation equal to or higher than <NUM>% parallel to the first axis <NUM> and parallel to the second axis <NUM>. The patch body <NUM> is further configured such that a tensile load of equal to or less than <NUM> N, preferably a tensile load of equal to or less than <NUM> N, is required for achieving a tensile elongation equal to or higher than <NUM>% in the corresponding direction.

Further, the patch body <NUM> is formed as a mesh made of non-woven fibres. The mesh comprises polytetrafluoroethylene fibres and/or expanded polytetrafluoroethylene fibres. In addition, the patch body <NUM> is impermeable to the material of the nucleus pulposus <NUM> of the intervertebral disc <NUM>.

In addition, the polytetrafluoroethylene and/or expanded polytetrafluoroethylene fibres have a yield strength between <NUM> x <NUM><NUM> Pa and <NUM> x <NUM><NUM> Pa. Thus, they can withstand the forces that are exerted on the patch <NUM> during movement of the spine <NUM>.

It can further be seen from <FIG> that the patch body <NUM> comprises a plurality of through openings <NUM>, in particular through holes, for receiving a corresponding number of fastening elements. More specifically, four through openings <NUM> are provided in the patch body <NUM> of the present embodiment, which are pairwise arranged in the direction of the first axis <NUM>.

The minimum distance <NUM> between a boundary <NUM> of each of the through openings <NUM> and a boundary <NUM> of the patch body <NUM> parallel to the first axis <NUM> is at least <NUM>%, preferably at least <NUM>%, of the length <NUM> of the patch body <NUM>.

Similarly, the minimum distance <NUM> between the boundary <NUM> of each of the through openings <NUM> and the boundary <NUM> of the patch body <NUM> parallel to the second axis <NUM> is at least <NUM>%, preferably at least <NUM>%, of the width <NUM> of the patch body <NUM>.

Due to the described arrangement of the through openings <NUM> relative to the boundary <NUM> of the patch body <NUM>, the risk of a tear of the patch body <NUM> around the through openings <NUM> can be reduced.

<FIG> shows a screw that can be used as each of the fastening elements <NUM> for fastening the patch body <NUM> to the spine <NUM>.

The patch <NUM> and the plurality of the fastening elements <NUM> form a surgical kit.

In <FIG>, the patch <NUM> is shown in a state that it is affixed to the spine <NUM> for covering the defect in the annulus fibrosus <NUM> of the intervertebral disc <NUM>.

More specifically, the patch <NUM> is fastened to the vertebrae <NUM>, between which the intervertebral disc <NUM> having the defect lies. For a better overview, the fastening elements <NUM>, via which the fixation of the patch <NUM> to the vertebrae <NUM> is realised, are omitted from <FIG>.

It can particularly be understood from <FIG> that, in its affixed state to the spine <NUM>, the patch <NUM> has taken the shape of the intervertebral disc <NUM> and the vertebrae <NUM> in its overlapping areas with the intervertebral disc <NUM> and the vertebrae <NUM>, respectively. Thus, due to its flexibility, the patch <NUM> is able to effectively seal the defect in the annulus fibrosus <NUM> of the intervertebral disc <NUM>.

It can be further derived from <FIG> that the first axis <NUM> of the patch body <NUM> is substantially parallel to the longitudinal axis <NUM> of the person's body, while the second axis <NUM> is substantially parallel to the mediolateral axis <NUM> of the person's body.

To highlight the advantages of the patch <NUM> of the present invention, the result of a simulation (finite element analysis) of an exemplary embodiment of a patch <NUM> of the present invention being subjected to a tensile force of <NUM> N parallel to the first axis <NUM>, as shown in <FIG>, is compared to the result of a simulation (finite element analysis) of an example of another patch <NUM> (not according to the present invention) being subjected to the same tensile force, as shown in <FIG>. It is noted that <FIG> show the deformed patches <NUM>, <NUM> after they have each been subjected to the aforementioned tensile load parallel to the first axis <NUM>.

Both patches <NUM>, <NUM> have the same initial dimensions prior to loading. In particular, the patches <NUM>, <NUM> have a length of <NUM>, a width of <NUM> and a thickness of <NUM>,<NUM>. Further, all through openings <NUM> of the patch <NUM> are formed as through holes with a circular cross-section with a diameter of <NUM>, wherein a distance between the centre of the circular cross-section of the through holes parallel to the first axis <NUM> is <NUM> and a distance between the centre of the circular cross-section of the through holes parallel to the second axis <NUM> is <NUM>. The patch <NUM> comprises through openings <NUM> that are in terms of their size, shape and positional arrangement on the patch body <NUM> identical to the through openings <NUM> of the patch <NUM>. On the other hand, the patch <NUM> according to the exemplary embodiment of the present invention has a tensile stiffness of <NUM> x <NUM><NUM> N/m parallel to the first axis <NUM> and the second axis <NUM> and is formed as a mesh comprising polytetrafluoroethylene and/or expanded polytetrafluoroethylene fibres, whereas the patch <NUM> has a tensile stiffness of <NUM> x <NUM><NUM> N/m in the corresponding directions and is made of PTFE (solid material not made of fibres).

The length of the deformed patch <NUM> of the present invention is denoted by the reference sign <NUM>' in <FIG>, while the length of the example of the deformed patch <NUM> is denoted by the reference sign <NUM> in <FIG>.

When comparing <FIG>, it becomes apparent that the length <NUM>' of the deformed patch <NUM> according to the exemplary embodiment of the present invention is greater than the length <NUM> of the patch <NUM>. In other words, the patch <NUM> according to the exemplary embodiment of the present invention has experienced a greater tensile deformation parallel to the first axis <NUM> than the tensile deformation that the patch <NUM> according to the example not being subject to the present invention has experienced in the corresponding direction.

In particular, the tensile deformation of the patch <NUM> at the middle of the patch body <NUM> in a direction parallel to the first axis <NUM> according to the exemplary embodiment of the present invention is <NUM>,<NUM>, whereas the corresponding tensile deformation of the patch <NUM> is <NUM>,<NUM>.

Thus, the patch <NUM> according to the exemplary embodiment of the present invention is able to sufficiently deform in an elastic manner during the movement of the spine <NUM>, thereby matching the displacement of the vertebrae <NUM> relative to each other, e.g. during a bending movement of the person as denoted by arrow <NUM> in <FIG>. Further, the force needed for achieving said deformation lies within the range of the forces exerted on the vertebrae <NUM> during the movement of the spine <NUM>. On the contrary, the patch <NUM> is so stiff that it would negatively affect the mobility of the spine <NUM> and more specifically of the vertebrae <NUM>.

<FIG> refer to a patch <NUM> according to a second embodiment of the present invention.

The patch <NUM> according to the second embodiment differs from the patch <NUM> according to the first embodiment in that the patch <NUM> according to the second embodiment comprises a plurality, in particular four, reinforcing and stress distribution elements <NUM>.

Each reinforcing and stress distribution element <NUM> is provided on the patch body <NUM> around the boundary <NUM> of a corresponding through opening <NUM>.

Further, each of the reinforcing and stress distribution elements <NUM> is formed as an insert that is inserted in a corresponding through opening <NUM>. In particular, all reinforcing and stress distribution elements <NUM> are formed as grommets that are made of plastic or metal and each have a main grommet body <NUM> and two collars <NUM> integrally formed with the main grommet body <NUM>. Each collar <NUM> is arranged on a main face <NUM> of the patch body <NUM>, while the main grommet body <NUM> is inserted in the through opening <NUM>.

The reinforcing and/or stress distribution elements <NUM> can in particular be fixedly connected to the patch body <NUM>.

The reinforcing and stress distribution elements <NUM> provide protection to the patch body <NUM> around the through openings <NUM> and are configured to prevent or minimize stress concentrations around the through openings <NUM> by distributing stresses over a larger area of the patch body <NUM>.

The depicted and described features and further properties of the invention's embodiments can arbitrarily be isolated and recombined without leaving the gist of the present invention.

Though the patch <NUM> according to the first and second embodiments has been described and is primarily intended as a solution for covering a defect in the annulus fibrosus of an intervertebral disc of a spine of a human, it is possible that the patch <NUM> can be used in animals, in particular primates, as well.

Claim 1:
A patch (<NUM>) for covering a defect in the annulus fibrosus of an intervertebral disc, and in particular also in the posterior longitudinal ligament, of a spine (<NUM>), comprising a patch body (<NUM>) that is formed as a sheet and has a tensile stiffness between <NUM> x <NUM><NUM> N/m and <NUM> x <NUM><NUM> N/m, preferably between <NUM> x <NUM><NUM> N/m and <NUM> x <NUM><NUM> N/m, parallel to a first axis (<NUM>), wherein the first axis (<NUM>) lies on a main face (<NUM>) of the patch body (<NUM>), wherein the patch body (<NUM>) is formed as a mesh made of non-woven fibres,
preferably wherein the patch body (<NUM>) has a tensile stiffness between <NUM> x <NUM><NUM> N/m and <NUM> x <NUM><NUM> N/m, preferably between <NUM> x <NUM><NUM> N/m and <NUM> x <NUM><NUM> N/m, parallel to a second axis (<NUM>), wherein the second axis (<NUM>) lies on the main face (<NUM>) of the patch body (<NUM>) and is perpendicular to the first axis (<NUM>).