Patent Application
20240016613
The invention relates to a medical implant, particularly for meniscus repair or replacement, a method for manufacturing the medical implant, a medical product comprising the medical implant and a packaging, an alignment tool, a method for customizing a medical implant, and a surgical felting instrument.
Various medical implants to replace or repair defects in soft biological tissues, such as tendons, ligaments and cartilage, are know from the prior art. These are typically connected to parts of the body by sutures (in case of integration into soft tissues) or anchor structures (in case of integration into bone).
In general, although medical implants are designed to resemble biological structures that they replace, many implants substantially differ from the natural structures in their mechanical properties, which may lead to complications. Furthermore, the use of sutures and bone anchors to fix the medical implants to adjacent biological structures bears the danger of breakage or pullout, resulting in a need for repeated surgery.
For example, knee injuries are worldwide an issue in medicine and the number of operations related to the knee joints are increasing continuously. Almost 15% of the total cases are associated with loss of tissue of either one of the two menisci. The meniscus is a cartilaginous tissue placed in the knee that helps the stabilization and lubrication of it especially during tension and torsion of the joint. The problem of the loss of meniscal tissue forces the individual to a restriction of physical activities and results in a degeneration of the cartilage in the knee with the increasing of age. Low vascularization of the meniscal tissue combined with other factors, prevents the regeneration of the cells in the meniscal cartilage and leads to the nowadays solution of replacement of it with an artificial implant. The method of substituting the damaged part seems to diminish or avoid degeneration of the meniscus. Many different implants have already been developed or are currently in study.
Both approaches, total and partial replacement follow the meniscectomy which is a removal of meniscal tissue. When substituting only the damaged part, the fixation is performed with sutures that connects the implant to the intact healthy meniscus, whereas the total replacement is placed and kept in position through screws in the bones or simply by interlocking the implant between femur and tibia. The partial replacement preserves as much healthy natural meniscus as possible.
CN 204723455 U discloses a double-layered meniscus implant comprising a base layer from a PLGA fiber felt and a surface layer from a gelatin fiber felt.
CN 107669373 A describes an artificial meniscus implant from a fiber woven structure comprising interwoven radial and circumferential fibers.
US 2017/0202672 A1 discloses an artificial meniscus comprising a polycarbonate-urethane resin reinforced by an inert fiber fabric distributed throughout the resin.
Some core challenges of these and other meniscus implants according to the prior art, especially for the partial meniscus repair, concerns the suturing fixation, the surface match and the mimic of the mechanical properties in different zones. Suturing fixation might be demanding and intricated for the surgeon and furthermore the strength of the attachment depends on very few stitches and the entire load is spread on them. Non-optimal partial implants can cause surface or size disparities that has as a possible consequence a higher contact stress. This might increase the friction between the articulating cartilage and the meniscus. The mechanical properties of the native meniscus are not isotropic, instead, they vary in different zones to fulfil the needs of different load bearings. The artificial replacements mentioned above do not have controllable mechanical properties in different zones.
Thus, the objective of the present invention is to provide a medical implant, particularly for meniscus replacement or repair, which overcomes the above-stated disadvantages of the prior art, in particular a medical implant which more closely resembles the mechanical properties of the natural replaced or repaired tissue.
This objective is attained by the subject matter of the independent claims. Embodiments of the invention are specified in the dependent claims and described hereafter.
A first aspect of the invention relates to a medical implant, particularly for lateral or medial meniscus repair or replacement, wherein the medical implant extends along a plane perpendicular to a first axis, and wherein the medical implant comprises, particularly is at least partially formed from, a felt material comprising a plurality of fibers.
According to a first variant of the first aspect of the invention, a density of the fibers varies along the plane, particularly resulting in a varying compressive strength along said first axis.
According to a second variant of the first aspect of the invention (which may be applied independently of the first variant or in combination with the first variant), a percentage of the fibers aligned in a circumferential direction in respect of the first axis differs along the plane of the implant, particularly resulting in a varying tensile strength of the medical implant along the plane, wherein the tensile strength is measured parallel to the plane, more particularly wherein the tensile strength is measured in the circumferential direction.
As used herein, the term “medical implant” describes a device suitable for being inserted into a human or animal body, particularly to replace or augment damaged parts of the body.
The medical implant extends along a plane. Of course, the implant does not have to be perfectly planar, i.e., the implant may be curved along the first and second coordinate. Furthermore, the implant may be deformable, particularly wherein the implant is planar in an undeformed state (without applying external forces). The first axis can be described as a surface normal of the plane, e.g., in case the plane extends along the width and length of the implant, the first axis would extend along the height. In case of a meniscus implant, said plane may extend essentially in the medial-to-lateral and anterior-to-posterior direction, and the first axis may extend parallel to the tibia bone when the medical implant is arranged in the natural location of the meniscus.
The density of fibers is defined as the number of fibers per unit of volume of the medical implant. In particular, the percentage of the fibers aligned in the circumferential direction relates to the sum of the length of each individual fiber extending in the circumferential direction divided by the total length. The term “compressive strength” as used herein is a physical parameter describing the amount of compressive deformation of the medical implant in the direction of the first axis per force applied in the direction of the first axis. The term “tensile strength” as used herein is a physical parameter describing amount of stretching deformation of the medical implant in a direction parallel to the plane, particularly in the circumferential direction, per force applied in the direction parallel to the plane, particularly in the circumferential direction.
According to the invention, the density of the fibers and/or the percentage of fibers aligned in the circumferential direction varies along the plane, meaning the density and/or percentage is inhomogeneous in at least one direction along the plane, particularly resulting in a corresponding inhomogeneous distribution of compressive strength and/or tensile strength. In particular, this compressive/tensile strength distribution resembles the compressive/tensile strength distribution of the natural lateral or medial meniscus, resulting in improved function of the implant. The inhomogeneous distribution of fiber density and/or fiber alignment, and the corresponding compressive/tensile strength distribution may be characterized by different zones divided by a stepwise increase or decrease of density and/or fiber alignment or characterized by a gradual increase or decrease of density and/or fiber alignment.
The areas with increased density of the fibers may also result in a locally decreased thickness of the medical implant along the first axis. Therefore, in particular, the 3-dimensional structure of the implant is controllable by tuning the density of the fibers.
Due to the felt material, the 3D structure and mechanical properties of the medical implant may be easily adapted to the needs of the medical application and individual patient: To this end, for example, a felting needle comprising at least one barb may be advanced through the felt material at specific locations and in a specific direction to achieve certain densities and fiber alignments. E.g., by felting in a specified direction, the fibers can be preferentially aligned along this direction.
An additional advantage of the felt material is that it may be tightly connected to biological soft tissue, such as tendon, ligament or cartilage, by placing the implant on the tissue and repeatedly advancing a surgical felting needle comprising at least one barb through the felt material and the tissue resulting in fibers of the felt material being introduced into the tissue to achieve a mechanically strong suture-less fixation that spreads the anchorage on many different spots.
In certain embodiments, the medical implant comprises an outside surface, wherein the density of the fibers and/or the percentage of the fibers aligned in the circumferential direction increases in a radial direction in respect of the first axis towards the outside surface, particularly such that the compressive strength of the medical implant measured parallel to the first axis and/or the tensile strength of the medical implant measured parallel to the plane, more particularly in the circumferential direction, increases in the radial direction towards the outside surface. The outside surface particularly extends in a circumferential direction in respect of the first axis. In particular, in case of a meniscus implant, the outside surface may extend circumferentially to the first axis from the anterior side via the medial side or lateral side to the posterior side.
This distribution of compressive strength and/or tensile strength resembles the mechanical properties of the natural meniscus (e.g., a similar load distribution as that of the natural meniscus) and thus improves the function of the medical implant.
In certain embodiments, the medical implant comprises a plurality of zones, wherein the density of the fibers and/or the percentage of the fibers aligned in the circumferential direction varies between the zones, wherein particularly the zones are arranged along the radial direction. In certain embodiments, the medical implant extends from a first end via a central section towards a second end along a curved line extending in a circumferential direction in respect of the first axis, wherein the medical implant comprises a central recess, around which the curved line extends. In other words, the medical implant is C-shaped or crescent moon shaped, particularly resembling the shape of the natural lateral or medial meniscus.
In certain embodiments, the plurality of zones comprises a first zone, a second zone, a third zone and/or a fourth zone.
In certain embodiments, the zones each extend in the plane between the first end and the second end along the curved line. In certain embodiments, the first zone is arranged along the edge of the central recess on the inside of the medical implant. In certain embodiments, the second zone is arranged outside of the first zone along the radial direction, and the third zone is arranged outside of the second zone along an outside surface of the medical implant. In certain embodiments, the fourth zone is arranged around the entire outside surface, wherein particularly the fourth zone is formed by the first cover layer and/or the second cover layer.
In certain embodiments, the density of the fibers increases from the first zone to the second zone, and from the second zone to the third zone. The varying compressive strength in the plane particularly resembles the mechanical properties of the natural meniscus.
In certain embodiments, the percentage of the fibers aligned in the circumferential direction differ between the first zone, the second zone, the third zone and/or the fourth zone.
In certain embodiments, the percentage of fibers aligned in the circumferential direction increases from the first zone towards the second zone, and from the second zone towards the third zone, and then decreases from the third zone to the fourth zone.
In certain embodiments, the percentage of fibers aligned in the circumferential direction is less than 60% in the first zone, 30% to 80% in the second zone, more than 50% in the third zone, and less than 60% in the fourth zone.
According to certain embodiments, the tensile strength of the medical implant in the plane P, particularly in the circumferential direction C, is in the range of 0,050 MPa to 90 MPa in the first zone, 0,750 MPa to 140 MPa in the second zone, 0,100 MPa to 176 MPa in the third zone, and 0,050 MPa to 16 MPa in the fourth zone.
In certain embodiments, the medical implant is formed from a plurality of layers comprising the felt material, wherein the layers are stacked in a direction parallel to the first axis, and wherein the layers are connected by felting. Therein, “felting” refers to advancing a felting needle comprising at least one barb repeatedly through at least two adjacent stacked layers resulting in fibers of one layer extending into the other layer to connect the layers.
Stacking layers comprising a felt material allows a simple and versatile manufacturing method for the medical implant.
In certain embodiments, the density of the fibers of at least one layer of the plurality of layers, particularly the density of the fibers of each layer of the plurality of layers, varies along the plane, particularly resulting in a varying compressive strength of the respective layer along the first axis.
In certain embodiments, the percentage of the fibers aligned in the circumferential direction of at least one layer of the plurality of layers, particularly the percentage of the fibers aligned in the circumferential direction of the fibers of each layer of the plurality of layers, varies along the plane, particularly resulting in a varying tensile strength of the respective layer along the plane, particularly in the circumferential direction.
In certain embodiments, at least one layer of the plurality of layers, particularly each layer of the plurality of layers, comprises an outside edge, wherein the density of the fibers and/or the percentage of the fibers aligned in the circumferential direction increases in a radial direction in respect of the first axis towards the outside edge, particularly such that the compressive strength of the respective layer measured parallel to the first axis and/or the tensile strength of the respective layer measured parallel to the plane, more particularly in the circumferential direction, increases in the radial direction towards the outside edge. The outside edge particularly extends in a circumferential direction in respect of the first axis. In particular, in case of a meniscus implant, the outside edges in the implant assembled from the layers may extend circumferentially to the first axis from the anterior side via the medial side or lateral side to the posterior side.
In certain embodiments, at least one layer of the plurality of layers, particularly each layer of the plurality of layers, comprises a plurality of zones, wherein the density of the fibers and/or the percentage of the fibers aligned in the circumferential direction varies between the zones, wherein particularly the zones are arranged along the radial direction.
By cutting the above-described layers into a desired shape and connecting the layers by felting, a medical implant having a desired 3D-distribution of mechanical properties can be easily manufactured.
In certain embodiments, the layers comprise a bottom layer and a top layer, wherein an arc length of the bottom layer extending along the curved line is greater than an arc length of the top layer extending along the curved line, such that a thickness of the medical implant measured parallel to the first axis increases, particularly stepwise, from the first end towards the central section and/or from the second end towards the central section. In case of a stepwise thickness increase, these steps may be smoothed by providing a cover layer that covers the bottom layer and the top layer. The bottom and top layers comprising the felt material may be connected, for instance, by felting.
In certain embodiments, the layers comprise at least one intermediate layer between the bottom layer and the top layer, wherein an arc length of the at least one intermediate layer is between the arc length of the bottom layer and the arc length of the top layer.
In this manner, a desired 3D-architecture of the implant comprises different steps in thickness and accordingly a desired steepness can be achieved in an easy manner. The bottom, top and intermediate layers comprising the felt material may be connected, for instance, by felting.
In certain embodiments, the medical implant comprises a first cover layer covering the bottom layer and the top layer, and particularly the at least one intermediate layer, on a top surface extending along the plane of the medical implant, particularly from the first end towards the second end. This advantageously results in smoothing of a stepwise thickness increase mediated by the different layers.
In certain embodiments, the medical implant comprises a second cover layer covering the bottom layer and the top layer, and particularly the at least one intermediate layer on a rim surface extending parallel to the first axis and circumferentially in respect of the first axis. This particularly provides a smooth lateral rim surface.
In certain embodiments, the medical implant comprises a strip comprising the felt material, wherein the strip is arranged circumferentially in respect of the first axis along an outside surface of the medical implant between the bottom layer and the top layer.
In certain embodiments, the strip extends along the curved line.
In certain embodiments, the strip has an arc length along the curved line which is shorter than the arc length of the bottom layer and shorter than the arc length of the top layer.
In certain embodiments, the medical implant comprises a replacement member configured to replace a part of a soft biological tissue, particularly a meniscus, and a supporting body connected to the replacement member, wherein the supporting body extends from the first end via the central section to the second end along the curved line in the circumferential direction, and wherein the replacement member is arranged on a bottom surface of the supporting body (arranged parallel to the plane), wherein the replacement member covers a partial segment of the bottom surface. In particular, the supporting body comprises a central recess, around which the curved line extends. In other words, the supporting body is C-shaped or crescent moon shaped, resembling the shape of the natural lateral or medial meniscus.
In certain embodiments, the supporting body and/or the replacement member is formed by a plurality of layers comprising a felt material.
In certain embodiments, the replacement member has a thickness measured parallel to the first axis which is greater than a thickness of the supporting body measured parallel to the first axis.
In case of a meniscus implant, the replacement member may be inserted in a gap in the natural meniscus obtained by surgical removal of a part of the meniscus, and the supporting body may be placed on top of the natural meniscus to mechanically stabilize the replacement member.
In certain embodiments, the medical implant, particularly the felt material, comprises or consists of polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyethylene (PE), poly(lactic-co-glycolic acid) fiber felt, biometric collagen, silk fibers, polycarbonate polyurethane (PCU) fibers, or polycaprolactone (PCL).
A second aspect of the invention relates to a method of manufacturing a medical implant, particularly the medical implant according to the first aspect, wherein at least one sheet comprising a felt material is provided, the sheet extending along a plane perpendicular to a first axis, wherein the felt material comprises a plurality of fibers, and wherein a felting needle comprising at least one barb is repeatedly advanced through the sheet at specified locations to increase the density of the fibers, particularly such that the compressive strength of the sheet measured along the first axis is increased at the specified locations, and/or to increase the percentage of fibers aligned in a circumferential direction in respect of the first axis at the specified locations, such that the tensile strength of the sheet measured along the plane, more particularly in the circumferential direction, is increased at the specified locations.
The barb or barbs of the felting needle pull fibers of the felt material in the direction of movement of the needle, and therefore increase the percentage of fibers aligned along this direction. In addition, particularly due to entanglement of fibers caused by the felting needle, the density of the fibers along the first axis is increased, which may result in a decreased thickness (in the direction of felting) of the felt material at the location where the felting needle is introduced.
In certain embodiments of the method of manufacturing, a plurality of layers comprising a felt material are provided, wherein the layers are connected by repeatedly advancing a felting needle comprising at least one barb through the layers to connect the layers.
In certain embodiments, the layers are assembled from a raw or processed felt material comprising fibers.
In certain embodiments, the layers are formed by electrospinning.
In certain embodiments, the layers are formed by 3D printing.
A third aspect of the invention relates to a medical product comprising a medical implant, particularly according to the first aspect, and a transparent packaging, wherein the packaging comprises printed markings comprising an outline marking of the shape of the medical implant, a radial scale marking and a circumferential scale marking, wherein the medical implant is arranged in the packaging, such that the outline marking is aligned with the medical implant.
The packaging may be, e.g., a pouch or a blister. In particular, the medical implant is sealed in the packaging, more particularly in an airtight manner.
In case of a meniscus implant, the outline marking may extend along a curved line extending in a circumferential direction in respect of the first axis around a central recess. In other words, the outline marking is C-shaped or crescent moon shaped, resembling the shape of the natural lateral or medial meniscus.
A fourth aspect of the invention relates to an alignment tool comprising a working surface configured to receive the medical implant according to the first aspect and/or the medical product according to the third aspect. The alignment tool further comprises a holder configured to be placed on the working surface, wherein the holder comprises a cutout having a size and shape of the medical implant, such that the outline marking and the medical implant can be aligned with the cutout.
This alignment tool particularly provides a working surface for accurate alignment and connection by a felting needle of different components of the medical implant, e.g. of the above-described layers (such as the top layer, the bottom layer and the at least one intermediate layer). The alignment tool particularly aids in connecting a supporting body to a replacement member, thereby generating a two-part implant for partial meniscus replacement.
In certain embodiments, the holder of the alignment tool comprises a plurality of notches arranged around an edge of the cutout, wherein the notches extend in the radial direction and/or in the circumferential direction.
Such notches facilitate cutting with a scalpel along the radial direction to cut a medical implant placed on the working surface into a desired shape.
In certain embodiments, the alignment tool comprises at least one fixing means configured to fix the holder to the working surface, particularly to clamp the medical product between the working surface and the holder.
In certain embodiments, the working surface is comprised in a replaceable part of the alignment tool.
In certain embodiments, the working surface is smooth.
In certain embodiments, the working surface is covered by a spongy material.
A smooth or a spongy surface may be advantageous for felting on the working surface, e.g. to avoid damage from the needle to the working surface by the spongy material.
A fifth aspect of the invention relates to a method for customizing a medical implant, particularly according to the first aspect, wherein a medical product according to the second aspect is provided, and wherein a desired shape of the medical implant to be customized is marked on the transparent packaging of the medical product using the radial scale marking and the circumferential scale marking, and wherein a piece is cut out of the medical implant and the packaging using the marked desired shape.
In certain embodiments, to obtain a medical implant custom-fit for partial meniscus replacement, a desired depth of the medical implant from the central recess outwards along the radial scale marking and a start coordinate defined by the distance to a root of the outline marking along the circumferential scale marking (the root being defined by a location of an open side of the central recess) are determined and a first line extending from the central recess along the radial scale marking by the determined depth is marked on the packaging, e.g. with a pen, at the start coordinate. Next, in particular, an end coordinate of the desired implant along the circumferential scale marking is determined and a second line is drawn on the packaging along the circumferential scale marking from the start coordinate to the end coordinate. Finally, in particular, a third line is drawn on the packaging from the end coordinate along the radial scale marking inside towards the edge of the central recess. In particular, the medical implant having the desired shape is subsequently cut out along the marked desired shape on the packaging, particularly using scissors or a scalpel.
In particular, this provides an easy and accurate method of generating a custom-made implant for partial meniscus replacement.
In certain embodiments, a supporting body comprising a felt material is arranged on the working surface of the alignment tool, wherein the medical product (which comprises a hole generated by cutting out the piece of the medical implant) and the packaging are arranged on the supporting body, and wherein the piece cut out of the medical implant is arranged in the hole of the packaging, and wherein a felting needle comprising at least one barb, particularly the surgical felting needle according to the sixth aspect, is repeatedly advanced through the piece and the supporting body, thereby connecting the piece to the supporting body by felting.
In particular, the piece serves as a replacement member for a soft biological tissue, such as during partial meniscus replacement.
The alignment tool particularly aids in connecting a supporting body to a replacement member, thereby generating a two-part implant for partial meniscus replacement.
A sixth aspect of the invention relates to a felting instrument, particularly a surgical felting instrument, comprising a felting needle, the felting needle comprising at least one barb, wherein the felting instrument comprises a drive configured to move the felting needle back and forth along a longitudinal axis.
By the at least one barb of the felting needle, the fibers of a felt material are pushed and/or pulled when the needle is advanced through the felt material. Thereby, it is possible to connect different pieces of felt material, connect felt material to biological tissue, and tune the mechanical and structural properties of the medical implant by increasing the density of the fibers and altering the fiber alignment as described above.
In particular, the felting needle comprises a plurality of barbs, more particularly at least one forward barb extending towards the tip of the felting needle and configured to push fibers when the needle moves forward into the felt material and pull fibers when the needle moves in the reverse direction away from the felt material, and at least one reverse barb extending in the opposite direction away from the tip of the felting needle to pull fibers when the needle moves forward into the felt material and push fibers when the needle moves in the opposite direction away from the felt material.
In certain embodiments, the felting needle is curved.
The curved design in the needle results in a reduced penetration depth into tissue, which avoids the tip of the needle touching and potentially damaging a bone (e.g. in case of connecting a medical implant to a soft tissue, such as a meniscus, in the vicinity of a bone, or to avoid the tip of the needle touching and potentially damaging a working surface (e.g., of the alignment tool), e.g., during connection of components (such as biological soft tissue) of the medical implant.
In certain embodiments, the felting instrument comprises a supporting member configured to hold a medical implant comprising a felt material comprising a plurality of fibers, particularly a medical implant according to the first aspect, in place on a biological soft tissue, particularly a meniscus, such that the felting needle of the felting instrument can be advanced through the medical implant and the soft tissue to connect the medical implant to the biological soft tissue.
The supporting member avoids displacement of the medical implant relative to the soft biological tissue (e.g. a meniscus) during connection of the medical implant to the biological tissue by felting, which help to keep the implant stable and improves the performance of the surgeon. Moreover, the supporting member particularly avoids that the felting needle touches and potentially damages a bone in the vicinity of the soft tissue.
In certain embodiments, the supporting member comprises a lower member configured to be arranged below the soft biological tissue, particularly between the soft biological tissue and a bone, and/or through the soft biological tissue.
In certain embodiments, the lower member comprises at least one needle comprising a tip configured to penetrate the soft biological tissue.
For example, during meniscus repair or replacement, the lower member may be advanced between the tibia bone and the natural meniscus. Optionally, in case the lower member comprises a needle with a sharp tip, the lower member may be advanced at least partially through the natural meniscus.
In certain embodiments, the supporting member comprises an upper member configured to be arranged on the medical implant, particularly to apply pressure on the medical implant.
By means of the upper member, it is possible to apply pressure on the medical implant placed on the biological soft tissue, e.g. the meniscus to hold the implant in place.
In certain embodiments, the lower member comprises an end section that is flippable to connect the end section to the upper member. In particular, a cage-like compartment holding the assembly between the medical implant and the soft biological tissue is thereby formed.
The cage like-compartment provides further stabilization of the implant on the tissue and provides a protected working environment for felting.
In certain embodiments, the supporting member is spaced apart from the felting needle of the felting instrument, such that contact between the felting needle and the supporting member is avoided when the felting needle moves back and forth along the longitudinal axis.
A seventh aspect of the invention relates to a surgical method for connecting a medical implant, particularly according to the first aspect, to soft biological tissue, wherein a felting instrument according to the sixth aspect is provided, wherein a medical implant comprising a felt material comprising fibers is arranged on a soft biological tissue, particularly on a ligament, a tendon or cartilage, more particularly on a medial or lateral meniscus, and wherein the felting needle of the felting instrument is repeatedly advanced through the medical implant and the soft biological tissue to connect the medical implant to the soft biological tissue.
Wherever alternatives for single separable features are laid out herein as “embodiments”, it is to be understood that such alternatives may be combined freely to form discrete embodiments of the invention disclosed herein.
The invention is further illustrated by the following examples and figures, from which further embodiments and advantages can be drawn. These examples are meant to illustrate the invention but not to limit its scope.
As part of a manufacturing method for a medical implant 100 according to the invention, a felting needle 210 of a felting instrument 200, the felting needle 210 comprising a plurality of barbs 211, may be advanced with its tip 212 into the sheet 10 and repeatedly moved back and forth along a longitudinal axis L, which in this case extends along the felting needle 210 (
Thereby, the barbs 211 of the felting needle 210 pull and push fibers 101 of the felt material F, which results in a changed density of the fibers 101 and in an altered alignment of the fibers 101 (
As best seen in
In the cross-sectional view of
In particular, the density of the fibers 101 of the felt material F in the medical implant 100 differ between the zones 111, 112, 113, 114 resulting in a varying compressive strength along the first axis A1 in the different zones 111, 112, 113, 114. More particularly, the density of the fibers 101 may increase from the first zone 111 to the second zone 112, and from the second zone 112 to the third zone 113. The varying compressive strength in the plane P particularly resembles the mechanical properties of the natural meniscus.
Furthermore, as illustrated in
Two spots per first, second and third zone 111, 112, 113 and one spot of the fourth zone 114 are enlarged and the corresponding fiber alignment is illustrated in the insets (wherein (a) marks the first zone 111, (b) marks the second zone 112, (c) marks the third zone 113, an (d) marks the fourth zone 114).
As shown in
According to certain embodiments, the percentage of fibers 101 aligned in the circumferential direction is less than 60% in the first zone 111, 30% to 80% in the second zone 112, more than 50% in the third zone 113, and less than 60% in the fourth zone 114.
The depicted alignment of fibers 101 in the circumferential direction C results in varying tensile strength of the medical implant in the different zones 111, 112, 113, 114, similar to the natural mechanical properties of the meniscus.
According to certain embodiments, the tensile strength of the medical implant in the plane P, particularly in the circumferential direction C, is in the range of 0,050 MPa to 90 MPa in the first zone 111, in the range of 0,750 MPa to 140 MPa in the second zone 112, in the range of 0,100 MPa to 176 MPa in the third zone 113, and in the range of 0,050 MPa to 16 MPa in the fourth zone 114.
According to a first embodiment, as shown in
After assembling the layers 140, 141, 142, 143, a first cover layer 144 is arranged on a top surface 103 of the medical implant 100 and connected by felting, resulting in the arrangement shown in
In addition, a second cover layer 145 (shown individually in
The first cover layer 144 and the second cover layer 145 may together constitute the fourth zone 114 as shown in
The medical implant 100 depicted in
As shown in
Thereby, a gradual thickness increase from the first and second end 121, 123 to the central section 122 (see
The medical implant 100 depicted in
In
The outline marking 321 resembles the size and shape of the medical implant 100 in the packaging 310 and the medical implant 100 is arranged in the packaging 310, such that it is aligned with the outline marking 321.
The radial scale markings 322 consist of lines (e.g. dotted lines as shown in
The circumferential scale markings 323 consist of lines (e.g. dotted lines as shown in
By the crossing lines of the radial scale markings 322 and circumferential scale markings 323, a coordinate system is defined on the surface of the medical implant 100 in the packaging 310.
Radial coordinates from 2 to 6 indicating a radial distance from the edge of the central recess 130 are indicated at the opening of the central recess 130.
In a similar manner, circumferential coordinates ranging from 0 to 27 (0 being a root at a radial edge 132 of an opening 131 of the central recess 130) are indicated along the periphery of the medical implant in both clockwise and counterclockwise directions.
The packaging 310 further comprises two through-holes 311 for aligning the medical product 300 on an alignment tool 400 (see below).
The markings 320 can be used to cut out a piece 11 of a pre-selected size and shape from the medical implant 100, using scissors 12 or alternatively a scalpel, particularly to form a custom-sized replacement part 160 of a two-part medical implant 100 as shown in
Part of this process is illustrated in
After an empty space has been created in the natural meniscus by partial meniscectomy, the position and size of the empty space is measured.
Then, as shown in
Next, as shown in
Finally, a radial third line 333 is drawn on the packaging from the end coordinate 335 inwards towards an edge of the central recess 130.
By cutting along the first line 331, the second line 332 and the third line 333, a piece 11 of the medical implant 100 of desired shape and size to fill the empty space in the natural meniscus can be cut out of the medical implant 100 in the medical product 300. A corresponding hole 340 is formed in the medical implant 100 and transparent packaging 310 (see
To assemble the cut-out piece 11 with a supporting body 170 to form a two-piece medical implant 100 as shown in
The alignment tool 400 comprises a working surface 401, wherein a partial surface of the working surface 401 having the crescent moon shape of the medical implant 100 is particularly covered with a special smooth or spongy material which facilities the use of a felting needle 210 on the working surface 401. The alignment tool 400 further comprises a holder 402 comprising a cutout 403 resembling the crescent moon shape of the medical implant 100. The part comprising the working surface 401 comprises four bores 406 with an inner thread and the holder 402 comprise corresponding through-holes 408 which can be aligned with the bores 406 when the holder 402 is placed on the working surface 401. The holder 402 can then be fixed on the working surface 401 using fixing members 405, such as screws, which are inserted into the bores 406 and through-holes 408.
Notches 407 are arranged around an edge 404 of the cutout 403 of the holder 402, the notches 407 extending in the radial direction or the circumferential direction. These notches 407 are designed to guide a scalpel during cutting the medical implant 100 into a desired shape, e.g. along the first line 331, the second line 332 and the third line 333 indicated in
First, the supporting body 170 is placed on the working surface 401 of the alignment tool 400, particularly on the spongy material 401a (
Subsequently, as shown in
Next, as illustrated in
Finally, the medical product 300 comprising the hole 340 and the finished medical implant 100 for partial meniscus replacement is removed from the alignment tool 400 (
As shown in
The felting instrument 200 comprises a felting needle 210 comprising at least one barb 211 and a drive 220 for moving the felting needle 210 back and forth along a longitudinal axis L.
In the depicted embodiment, the felting needle 210 is curved, such that the medical implant 100 can be conveniently connected to the soft tissue ST without touching the bone B.
In addition, as shown in
The flipping of the end section 235 is depicted in more detail in
Alternatively, as depicted in
The lower member 231 may be formed as a needle 232 comprising a sharp tip 233, such that the lower member 231 can penetrate into and through the soft tissue ST, which improves fixation of the soft tissue ST.
The supporting member 230 comprises at least one lower part 231 with a flippable end section 235 and at least one upper part 234, wherein the lower part 231 and the upper part 234 are attached to a first ring 236. A connecting rod 238 connects the first ring 236 to a second ring 237 which may be attached to the felting instrument 200.
The connecting rod 238 and the rings 236, 237 are arranged such that a shaft 239, in which the felting needle 210 moves, is spaced apart from the connecting rod 238 and extends through the first ring 236 and the second ring 237. Thereby, the felting needle 210 cannot touch the supporting member 230 avoiding damage to the components of the felting instrument 200.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20207151.0 | Nov 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/081586 | 11/12/2021 | WO |
