Microfiber implant made of wound filaments

Abstract

A method of making a microfiber implant. The method uses a manufacturing apparatus that includes a winding platform and a feeder head. The method includes advancing the microfilament from the feeder head toward the winding platform and repeatedly winding the microfilament around the winding platform. During winding, the feeder head moves laterally relative to the winding platform. The feeder head may be swept a plurality of times to stack winding layers. This results in a microfiber patch, which may then be further treated (e.g., applied with a collagen coating) to form a microfiber implant. Microfiber implants made by such winding techniques and devices for performing winding are also disclosed.

Description

Technical Field

[0001] The present invention relates to the fabrication of microfiber surgical implants for soft tissue repair (such as rotator cuff tendon repair). Background Art

[0002] Currently, research is underway to fabricate microfiber tissue engineering surgical implants through additive manufacturing techniques (such as 3D printing). Particularly in orthopedic medicine, research on collagen-containing microfiber implants has advanced sufficiently to mimic the collagen fibers arranged in natural ligaments and tendons. These arranged collagen fibers provide a scaffold for promoting ligament and tendon healing. There are many techniques for fabricating microfiber implants, such as electrospinning, wet extrusion, dry spinning, fused filament fabrication (FFF) 3D printing, and traditional biotextile methods (such as weaving, knitting, and weaving).

[0003] However, this prior art has various serious drawbacks. Electrospinning is limited by fouling and manufacturing complexity, such as high batch variability, poor in vivo cell infiltration due to limited porosity, and the use of harmful processing solvents. Although FFF printing has been explored for fabricating ligament and tendon analogs, the technique is inherently limited to simple fused structures that do not resemble natural tissue structures and their strength. Biotextile techniques are too complex and expensive for large-scale production. Therefore, alternative techniques for fabricating microfiber implants are needed. Summary of the Invention

[0004] The present invention relates to a microfiber implant made by winding microfilaments on a manufacturing device. The microfiber implant can be used for surgical repair of various types of fibrous connective tissues (such as tendons, fascia, ligaments, muscles, dermis, etc.) in musculoskeletal tissues (such as muscles or bones). Examples of various types of fibrous connective tissues that can be treated include rotator cuff tendon, patellar tendon, Achilles tendon, pelvic or abdominal fascia, anterior cruciate ligament, skin, dura mater, etc. A specific setting where the microfiber implant can be used is rotator cuff repair. Other clinical settings where the implant can be used are explained below.

[0005] As used herein, different terms are used to distinguish the various stages of the fabricated product, namely the microfiber patch and the microfiber implant. The term "microfiber patch" refers to an intermediate product made by winding microfilaments on a manufacturing device. After fabrication on the device, the microfiber patch may need further processing to become the final desired product. The term "microfiber implant" refers to the final product after any necessary post-processing of the microfiber patch. Examples of such post-processing are described below.

[0006] Manufacturing equipment. In one aspect, the present invention is a manufacturing equipment for manufacturing microfiber patches. The equipment includes one or more winding platforms on which microfiber patches are manufactured by winding one or more microfilaments.

[0007] Microfilaments. The microfilaments include polymer materials. Any suitable polymer materials can be used, including biological or synthetic polymers. Examples of suitable polymers include polydioxanone (PDO); poly(lactic-co-glycolic acid) (PLGA); poly-L-lactide (PLLA); polyetheretherketone (PEEK); polycaprolactone (PCL); ultra-high molecular weight polyethylene (UHMWPE); collagen; carbon fiber; or nanocellulose. The microfilaments can include a mixture of different polymers in any suitable proportion. The microfilaments are very thin (micron-scale diameter). For example, the diameter of the microfilaments can be in the range of 5 - 125 μm. The microfilaments can include single filaments (monofilaments) or multiple filaments (multifilaments or yarns).

[0008] Winding platforms. The winding platforms can be of any structure around which the microfilaments can be wound when the platform rotates. Examples of winding platforms include oval drum mandrels, cylindrical mandrels, or flat mandrels. The winding platforms can have regular or irregular shapes. Depending on factors such as the size of the microfiber patch, the winding platforms can have any suitable cross-sectional dimension (e.g., diameter). For example, the diameter (or the longest cross-sectional width) of the winding platforms can be in the range of 0.1 - 100 cm.

[0009] The winding platforms can have a non-stick coating (e.g., Teflon, polytetrafluoroethylene / PTFE) or be anodized to facilitate the removal of the microfiber patches wound thereon. The winding platforms can be tapered (narrowed) at one or both ends to facilitate the removal of the microfiber patches. The winding platforms can be dynamically adjusted in size. For example, the diameter can be made to contract to facilitate the removal of the microfiber patches.

[0010] The equipment can also include one or more brackets on which the winding platforms are mounted. For example, the equipment can have two brackets for holding each end of the winding platform. The winding platforms can be detached from the brackets to facilitate the removal of the microfiber patches. The manufacturing equipment is designed such that the winding platforms rotate around a rotation axis. The rotation axis can be aligned in any suitable direction relative to the winding platforms. The equipment can also include one or more rotating shafts for rotating the winding platforms.

[0011] Weaving loom frame. In some embodiments, the winding platform includes a crossbar of the weaving loom frame. That is to say, the device includes a weaving loom frame which includes two or more crossbars (i.e., the winding platform), and the microfilaments are wound around the crossbars. Depending on various factors, such as the desired shape of the microfiber implant, the crossbars can be aligned at any suitable angle relative to each other. For example, the crossbars can be aligned substantially parallel to each other. The cross-section of the crossbar can be of any suitable shape, such as circular (cylindrical), oval, square, flat or polygonal. Depending on factors such as the size of the microfiber patch, the crossbar can have any suitable cross-sectional dimension (e.g., diameter). For example, the diameter (or the longest cross-sectional width) of each crossbar can be in the range of 0.1 - 100 cm. Depending on factors such as the size of the desired microfiber patch, the crossbar can have any suitable length. For example, each crossbar is 2.0 - 90 cm long. The axis of rotation of the weaving loom frame can be substantially parallel to the crossbars.

[0012] Feeder head. The manufacturing device also includes one or more feeder heads for feeding the microfilaments onto the winding platform. The microfilaments are fed into the feeder head and then sent out from the feeder head. The microfilaments are sent out from the feeder head and advance towards the winding platform as it rotates. The microfilaments can be fed into or out of the feeder head in a passive or active manner. A simple passive feeding mechanism is to rotate and draw the microfilaments when the winding platform rotates (i.e., the winding platform "pulls in" the microfilaments). Further explanations regarding the winding of microfilaments by this mechanism are given below.

[0013] During the winding process, the feeder head moves laterally (translational motion) relative to the winding platform. The translational motion of the feeder head can vary according to the specific design of the microfiber patch, such as changes in direction, continuity (continuous or intermittent), speed, pauses, etc. The feeder head can have an adjustable angle to change the direction angle at which the microfilaments are sent towards the winding platform. During the manufacturing process, the adjustable angle can be dynamic. The adjustable angle can be on one or more (two or more) axes. In addition, the feeder head can be configured to perform multi-axis motion (two-axis or three-axis) relative to the winding platform to guide the microfilaments into the desired configuration. For example, the feeder head can move laterally relative to the winding platform and can also move towards / away from the winding platform.

[0014] The feeder head may include a coating bath through which the microfilaments pass before exiting. In another device design, the coating bath may be located outside the feeder head. For example, the microfilaments may pass through an external coating bath after leaving the feeder head. The coating bath contains a coating material for coating the microfilaments. Such coatings can be used for various beneficial purposes, such as a lubricant for winding or enhancing the therapeutic effect of the microfiber implant. Examples of possible coating materials include biomaterials (such as collagen or other components of the extracellular matrix, cells, growth factors, etc.), pharmaceuticals (such as small molecule drugs), bone mimicking materials (such as calcium sodium phosphate (such as "Bioglass")), or other surface reactive glass ceramic biomaterials, surfactants (such as "Plutonic" poloxamer), solvents (such as organic solvents or aqueous solutions (such as buffers or plain water)), or materials that promote the binding or joining of microfilaments together (such as resins).

[0015] Heating. The manufacturing device can be designed such that the winding platform can be heated. The purpose of this heating is explained below. Heat can be generated in any suitable manner. For example, the winding platform can be made of a conductive metal through which an electric current flows. The heat generated by the inductive resistance causes the winding platform to heat up. In another example, heating elements can be incorporated within the winding platform. As an alternative or supplement, the manufacturing device can have a separate heat source for applying heat to the microfiber patch, such as a laser or an infrared heater.

[0016] Additional features. The manufacturing device may also include one or more filament holders for holding the supply of microfilaments fed to the feeder head. Examples of filament holders include reels, spooling reels, circular trays, spindles, rollers, etc. If the feeder head has a coating bath (as described above), the device may also include a reservoir for holding and supplying the coating material. The reservoir is connected to the feeder head (e.g., a connecting tube through which the coating material travels from the reservoir to the coating bath).

[0017] Manufacturing method. In another aspect, the present invention is a method of making a microfiber implant. The method can use the manufacturing device described above. The microfiber patch (a precursor or intermediate of the microfiber implant) is made by a winding process on the manufacturing device. The microfilaments are wound around the winding platform of the manufacturing device multiple times.

[0018] During the winding process, the winding platform rotates about its axis of rotation. The microfilament is fed into the feeder head. The microfilament is sent out from the feeder head and advances towards the winding platform as it rotates. The output rate of the microfilament from the feeder head can be in the range of 25 - 800 cm / min. The microfilament is captured on the winding platform. The microfilament continues to be fed into and out of the feeder head with the lateral translational movement of the feeder head. The lateral (translational) travel speed of the feeder head can be in the range of 20 - 500 mm / min. The above steps are repeatedly executed to wind the microfilament around the winding platform.

[0019] For the loom frame, a single winding on the crossbar means that the microfilament travels around the first crossbar, passes through the second crossbar, around the second crossbar (and around and through any additional crossbars), and then back to the first crossbar. This loop constitutes a single turn of the microfilament. Multiple such windings are performed to make the microfiber patch.

[0020] Each turn can be placed adjacent to the previous turn. Adjacent turns do not necessarily have to touch each other. For example, having a small gap between the turns may help to form pores or grooves to facilitate the integration (mechanical or biological) of the microfiber implant with the surrounding tissue. Multiple microfilaments (two or more; for example, up to 10) can be deposited on the winding platform simultaneously.

[0021] The microfilament turns can be swept multiple times (two or more). This can stack multiple groups of turns together. Each sweep of the turns on the winding platform can make a single tangled layer for the microfiber patch. Thus, the microfiber patch can be composed of multiple tangled layers stacked on top of each other. The alternating sweeps can be in any direction, such as unidirectional (e.g., reset back to the initial position and only in the forward direction), bidirectional (e.g., back and forth in the forward / backward direction), or a combination thereof.

[0022] For example, the first sweep can make the first tangled layer, the second sweep can make the second tangled layer on top of the first tangled layer, the third sweep can make the third tangled layer on top of the second tangled layer, and so on. Through multiple sweeps, this process can make a microfiber patch with multiple tangled layers. The number of sweeps on the winding platform can be in the range of 3 - 50 times. Each sweep can form a tangled layer. This can make a microfiber patch with 3 - 50 tangled layers. Each sweep on the winding platform can make 3 - 70 turns of microfilament per centimeter on the winding platform.

[0023] The repeated winding process can be carried out with different degrees of continuity, such as continuously, intermittently, interrupted, etc. The microfiber patch can be made of an unbroken microfilament from start to finish. Or, the microfilament may break. That is, the microfiber patch can be made of multiple (two or more) separate microfilaments. For example, at the end of each sweep, the microfilament may break, and each tangled layer is made of separate microfilament strands.

[0024] In embodiments where the feeder head includes a coating bath, the microfilaments pass through it and are coated. The microfiber patch can be made of various types of microfilaments. For example, multiple microfilaments of different sizes or material compositions can be combined. For example, one type of microfilament can be used to make one entanglement layer, and then another different type of microfilament can be used to make the next entanglement layer.

[0025] Heating or fiber fusion. The manufacturing method can also include heating the winding platform or a part thereof. For a loom frame, one or more crossbars of the loom frame can be heated. This heating can be carried out during the microfilament winding process or after the winding is completed. The portions of the turns in contact with the heated part of the winding platform (such as the crossbar) will melt or soften, thereby thermally bonding the microfilaments. This will form one or more fusion regions on the microfiber patch. These fusion regions can serve as boundaries or stabilization regions for the microfiber implant. Alternatively, in the case where an adhesive (such as a collagen coating) is applied to the microfilaments or the microfiber patch, heating may cause the adhesive to melt with it (such as by polymerization, hardening, changing from a liquid to a gel / solid, etc.). This melting of the adhesive strengthens the resulting microfiber implant.

[0026] There are many possible variations of this heating process. For example, the individual crossbars of the loom frame can be heated to different temperatures. In another example, only certain parts of the winding platform can be heated. As an alternative or supplement to heating the winding platform, the microfiber patch can be exposed to different heat sources (such as a laser or an infrared heater) to form fusion regions thereon.

[0027] As an alternative or supplement to heating the winding platform, ultrasonic welding can be used to form fusion regions on the microfiber patch. The welding can be carried out continuously or in specific areas to form a structural pattern on the microfiber patch. Other techniques for forming fusion regions on the microfiber patch include compression, thermal plasma, cold plasma, or chemical solvents. Another option is to coat the microfiber patch with an adhesive layer of an adhesive material after the winding of the microfilaments is completed. The adhesive material can be a solvent polymer (such as PCL, PLA, or PDO), or other biocompatible chemicals in a suitable solvent. This adhesive coating can be applied to selected parts of the microfiber patch to form fusion regions thereon.

[0028] Post - winding processing and others. The microfiber patch fabricated on the manufacturing device can be further processed both inside and outside the manufacturing device. For example, the method can also include forming openings (such as holes or channels) in the microfiber patch (e.g., in the fusion region). These openings can be used to facilitate grasping instruments during surgical delivery or for holding sutures. These openings can be made by any suitable technique, such as punching, laser cutting, blade cutting, drilling, burning, or melting. Another example of further processing is to make the microfiber patch relatively large and cut the microfiber patch into smaller individual microfiber implants (i.e., mass production).

[0029] The microfiber patch fabricated on the manufacturing device can be detached from the winding platform in any suitable manner. For example, the microfiber patch can be removed from the winding platform by laterally sliding it towards one end on the winding platform until the microfiber patch detaches from the winding platform. Such a microfiber patch may be the final product or an intermediate product that requires further processing steps to become a microfiber implant made by this method. If the microfiber patch is an intermediate product, the manufacturing process will also include one or more additional processing steps, such as punching, final detailing, applying a coating, laser spot welding for reinforcement, chemical treatment for microfilament cross - linking, applying an adhesive, etc. For example, the microfiber patch can be coated with an adhesive material to help bond the fibers together. Examples of adhesives include polymeric materials such as polyvinylpyrrolidone (PVP), hydroxypropyl cellulose, microcrystalline cellulose, polyethylene glycol (PEG); and biomaterials such as collagen and platelet - rich plasma. The coating of the biomaterial can be freeze - dried.

[0030] The final product of the manufacturing process is a microfiber implant. This manufacturing process allows for many variations in the design of the microfiber implant, including variations in shape, size, composition, surface smoothness / roughness, etc. This manufacturing process can also produce microfiber implants with complex three - dimensional geometries.

[0031] Microfiber implant. Fabricating the microfiber implant in this way imparts various unique or superior characteristics, which are differentiating features. Thus, another aspect of the present invention is a microfiber implant having such differentiating features. Such differentiating features can be structural or functional. The microfiber implant can have one or more openings (such as holes or channels). These openings can be used to facilitate grasping instruments during surgical delivery or for holding or shuttling sutures, such as for arthroscopic delivery and fixation.

[0032] The microfiber implant includes multiple loops of one or more microfilaments. The size of the microfiber implant will vary depending on the specific clinical use. For example, the thickness of the microfiber implant ranges from 0.1 - 25 mm, the length ranges from 1.0 - 40 cm, and the width ranges from 0.1 - 30 cm. The surface area of the microfiber implant ranges from 2.0 - 250 cm 2 . The microfiber implant can have one or more fusion regions as described above. Such a microfiber implant can have a tensile strength of 100 - 3500 Newtons (N) and is suitable for soft tissue repair.

[0033] The fiber density of the microfiber implant will vary depending on the specific clinical use. As used herein, "fiber density" refers to the number of rows of microfilaments (at any depth) across a 1.0 - centimeter span measured in a transverse direction (i.e., cross - cut) perpendicular to the direction of microfilament winding. For example, the fiber density of the microfiber implant can range from 20 - 750 rows of microfilaments per centimeter span. As described above, the implant can include multiple entangled layers to increase the fiber density or implant thickness. For example, the microfiber implant can have 3 - 90 entangled layers.

[0034] As described above, the microfiber implant can have a coating (such as cryopreserved and lyophilized collagen). The collagen can be from any suitable source, including human, bovine, porcine, aquatic animals, or any other species. The collagen can be bioderived from an organism, synthesized (e.g., chemically synthesized), or made by recombinant techniques (e.g., cell culture). The collagen can be full - length or partial - length; examples of such include procollagen, telopeptide - containing collagen, telopeptide - free collagen, or gelatin. The collagen can also include any individual type of collagen, or multiple forms of collagen, or be mixed with other extracellular matrix components. For such a coated implant, the coating can form cross - link bridges between laterally adjacent microfilament strands. Depending on the clinical setting of use, the microfiber implant can have any suitable shape. For example, the shape of the implant can be ribbon - like, rectangular, square, triangular, rhomboid, trapezoidal, etc. The implant can be flat or three - dimensional. For example, since the implant is made by winding microfilaments, the implant can have a tubular shape, including a shell (of microfilament loops) and a hollow internal void. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 An example manufacturing device of the present invention is shown.

[0036] Figure 2 A close - up and partial internal view of the feeder head is shown.

[0037] Figures 3A - 3D An example of how the manufacturing device operates is shown. Figure 3A The initial winding of the microfilaments is shown.Figure 3B Shows the result after the loom frame is rotated by 180°. Figure 3C Shows the result after the loom frame is rotated by 360°. Figure 3D Shows the result after several complete rotations of the loom frame.

[0038] Figures 4A - 4E Shows an example of further processing of the microfiber patch. Figure 4A Shows the result after four back-and-forth windings are completed. Figure 4B Shows the result after heating the upper and lower edges of the microfiber patch. Figure 4C Shows the microfiber patch removed from the metal rod of the loom frame. Figure 4D Shows the resulting microfiber implant. Figure 4E Shows a cross-sectional side view of the microfiber implant.

[0039] Figure 5 Shows another example of a loom frame that can be used in the present invention.

[0040] Figure 6 Shows a flat mandrel as a winding platform.

[0041] Figure 7 Shows a drum mandrel as a winding platform.

[0042] Figure 8 Shows an example of how a crossbar is used for heating.

[0043] Figure 9 Shows an example of how infrared heating is used.

[0044] Figure 10 Shows an example of a tubular implant.

[0045] Figures 11 and 11B show examples of a block implant for rotator cuff tendon repair. Figure 11A Is a perspective view; Figure 11B Is a top view. Detailed Description

[0046] The accompanying drawings are provided to assist in understanding the present invention and illustrate examples of specific embodiments of the present invention. The drawings herein are not necessarily drawn to scale or actual size. For example, the size of components can be adjusted to fit the page size.

[0047] Figure 1A perspective front view of an exemplary manufacturing apparatus of the present invention is shown. The manufacturing apparatus 10 uses a loom frame 12 as a rotating platform. The loom frame 12 has two cylindrical metal rods 14 around which microfiber implants are wound. The rods 14 are mounted on side plates 16 which hold the rods 14 parallel and aligned with each other. The side plate 16 on the right side is detachable from the rod 14 to facilitate removal of the microfiber patch wound thereon. The metal rod 14 has a PTFE (polytetrafluoroethylene) coating to help prevent the microfiber patch from adhering thereto. Each side plate 16 is attached to a rotating shaft 18. The rotating shaft 18 on the left side is driven by a motor to rotate, causing the loom frame 12 to rotate about axis A, while the rotating shaft 18 on the right side rotates freely on a fixture.

[0048] Above the loom frame 12 is a platform for feeding microfilaments into the loom frame 12. The platform includes a feeder head 20 mounted on a transverse beam (not shown). On the transverse beam, the feeder head 20 can move horizontally back and forth relative to the loom frame 12. The traveling speed and angle (see below) of the feeder head 20 can be changed to adjust the pitch, spacing, and stratified net building or pattern of the winding. This stage also includes a reel 22 which stores the microfilaments wound thereon. Shown here is a short strand 24 of microfilaments unwound from the reel 22 and drawn into the feeder head 20.

[0049] Figure 2 A close-up and partial internal view of the feeder head 20 is shown. Inside the feeder head 20 is a coating bath 26 containing a collagen coating solution. The coating solution contains collagen mixed into an aqueous solvent. When the microfilament 24 passes through the feeder head 20, it is immersed in the coating bath 26 and coated with collagen before entering the loom frame 12. The direction of the feeder head 20 can be adjusted to change the direction angle (see dashed arrow C) of feeding the microfilament 24 towards the loom frame 12.

[0050] Figures 3A - 3D An example of how the manufacturing apparatus 10 operates is shown. In Figure 3A , the end of the microfilament strand 24 adheres to the bottom rod 14 of the loom frame 12 (e.g., with a bioadhesive or passive winding). The microfilament strand 24 disengages from the reel 24 and enters the feeder head 20. The loom frame 12 rotates on a rotating shaft (not shown) under motor power (see dashed arrow R). Figure 3B The result after the loom frame 12 rotates 180° is shown as the feeder head 20 automatically moves horizontally in the right direction (see dashed arrow T) with high precision. This is close to a complete winding of the microfilament strand 24. Note that the spacing between the turns 18 is enlarged for better visibility.

[0051] Figure 3C The result after the loom frame 12 rotates 360° and the feeder head 20 continues to travel in the right direction is shown. Figure 3DShows the result after the feeder head 20 continues to move in the right direction and the loom frame 12 makes several complete rotations. The result after multiple such windings is the microfiber filaments of the single layer 18. After sweeping across the loom frame 12 once, the feeder head 20 reverses direction and moves to the left, sweeping across the loom frame 12 again. This produces another microfiber winding layer stacked on top of the first winding layer 18 made in the first sweep. Under computer-controlled programming, the feeder head 20 makes two more left-right sweeps across the loom frame 12, for a total of four sweeps across the loom frame 12.

[0052] Figures 4A - 4E Shows an example of further processing of the microfiber patch 26. Figure 4A Shows the result after four back-and-forth windings are completed to make the desired microfiber patch 26. The rod 14 is a hollow cylinder with a heating element inside. As Figure 4B shown, the heating element is activated and causes the upper and lower edges of the microfiber patch 26 to melt and fuse. This produces two fused regions 28 at the edges of the microfiber patch 26. As Figure 4C shown, the right side plate 16 is removed from the metal rod 14, and the microfiber patch 26 is slid off the right free end of the metal rod 14 (see dashed arrow B). As Figure 4D shown, the microfiber patch 26 is coated with more collagen, and then holes 32 are made in the fused regions 28 by laser drilling. The final result is the microfiber implant 30. The holes 32 facilitate the surgical placement and fixation of the microfiber implant 30. Figure 4D Also shows how to measure the fiber density (in filaments per centimeter span) in the winding direction along the vertical axis F. Figure 4E Shows a cross-sectional side view of the microfiber implant 30. There is a stack of four layers 34 of microfiber loops.

[0053] Figure 5 Shows another example (front view) of a loom frame that can be used. The loom frame 40 has two cylindrical metal rods 44 around which the microfiber implant is wound. The rods 44 are mounted on side plates 46 that hold the rods 44 parallel and aligned with each other. Note that the rods 44 have tapered ends 42 where the diameter gradually narrows. Having tapered ends 42 can help in removing the microfiber patch wound around them.

[0054] Figure 6 Is a perspective view showing an example of a flat mandrel as a winding platform. The flat mandrel 50 uses a flat plate 52 that rotates around the transverse axis A. Figure 7 Is a perspective view showing an example of a drum mandrel as a winding platform. The drum mandrel 54 uses a hollow cylinder 56 that rotates around the transverse axis A.

[0055] Figure 8An example of how a crossbar is used for heating is shown. In this internal view, inside the hollow bar 60 (which is part of the loom frame) there is a heating coil 62. The heating coil 62 is connected to a power source via a power cord 64. Current is applied to the heating coil 62 to heat the bar 60 and form a fusion zone on the microfiber patch (not shown). Figure 9 An example of how infrared heating is used is shown. Above the roller mandrel 70 is an infrared heater 72. The infrared heater 72 radiates heat onto the microfiber patch (not shown) on the roller mandrel 70 to form a fusion zone on the microfiber patch.

[0056] Figure 10 An example of a tubular implant made on a roller mandrel is shown. The implant 80 includes a cylindrical outer shell 82 made by winding microfilaments. The implant 80 also includes a hollow internal void 84. The tubular implant 80 can be particularly used for repairing tubular body tissues such as blood vessels, nerves, respiratory tracts (such as the trachea), bones, or the gastrointestinal tract (such as the esophagus, intestines). The tubular implant 80 can also be used as a reinforcing sleeve for these and other body tissues (such as ligaments, tendons, muscles) to serve as a protective and healing covering.

[0057] Figure 11A (Perspective view) and 11B (top view) show an example of a block implant for rotator cuff tendon repair. The implant 90 includes a rectangular block 92 made by winding microfilaments. The implant 90 also includes two suture channels 94 drilled into the side of the block 92. These channels facilitate the surgical (arthroscopic) delivery to the implant site. The implant 90 also has a freeze-dried collagen coating made on the block 92.

[0058] Experimental work

[0059] The following is a brief summary of the experimental work carried out to verify the present invention. A report containing more detailed information is being submitted for journal publication. Prototype implant structure. The prototype microfiber implant was made using the techniques described above. The prototype was made using poly(L-lactide) and poly(propylene carbonate) microfilaments with a diameter of approximately 14 μm. (Non-test samples were also made using polydioxanone and cellulose fibers to demonstrate the process feasibility of other materials.) When the microfilaments were unwound from the spool, they were coated with collagen by passing through a collagen binder mixture in the trough. The filaments were wound around a rotating cylindrical roller mandrel. The spindle speed and the feeder head movement speed were adjusted such that a 1 cm wide loop was completed in 97 seconds. The feeder head output the filaments at a rate of approximately 143 cm / minute. The lateral movement speed of the feeder head was approximately 99 mm / minute.

[0060] Each sweep of the feeder head produces 10 turns / cm width. A total of 11 back-and-forth sweeps were made on the mandrel. Thus, the fiber density of the prototype implant is approximately 110 fibers / cm width. The dimensions of the prototype implant are suitable for tendon repair (2x3x0.2 mm) or ligament repair (1x3x0.2 mm). During or after winding, the prototype implant was removed from the mandrel and cultured at 37 °C to gel the collagen, making the implant more stable and cohesive. Further processing of the implant was carried out (details below). For comparison, a similar implant was fabricated using conventional fused filament fabrication (FFF) on a 3D printer. The process aimed to print an implant with rows of fibers of approximate prototype dimensions and shape. The selection of the print nozzle, speed, and height were optimized to produce rows of fibers as thin as possible while packing them as closely as possible, avoiding fusion. The FFF implant was dipped into a collagen solution to make a gel collagen coating.

[0061] Microscopic imaging. The prototype implant was examined by scanning electron microscopy and compared with implants produced by conventional FFF. The fiber alignment and topology were analyzed. The prototype implant showed a very high fiber alignment with collagen resin bridges between the fibers. This fiber alignment was higher compared to implants produced by FFF. On average, the fiber diameter produced by FFF exceeded 300 μm, while the fiber diameter in the prototype implant was approximately 14 μm.

[0062] Cell compatibility. The implants were cultured in a standard growth medium with a musculoskeletal cell type (C2C12 cells). Both the prototype and conventional FFF implants induced high metabolic activity in the cells and maintained this activity over 3 days of culture. The cells also maintained a healthy morphology. These results indicate that the prototype implant has high cell compatibility.

[0063] Degradation testing. The prototype implant was compared with implants produced by FFF to understand its degradation over time. The test was carried out according to ASTM F1635-16 (“Standard Test Method for In Vitro Degradation Testing of Hydrolytically Degradable Polymer Resins and Preformed Forms for Surgical Implants”). To test for mass loss due to degradation, the implants were immersed in an aqueous solution at 37 °C for up to 16 weeks (related to the common postoperative healing period in orthopedic injuries of soft tissues that require biomechanical support). The prototype implant showed a small amount of mass loss during a 2-week duration but not at 8 or 16 weeks; while the implants produced by FFF showed continuous mass loss over the entire 16-week duration. Both the prototype and FFF implants showed high physical stability (maintaining their shape and structure) and no material failure (no cracking, breaking, or thinning) over 16 weeks.

[0064] Tensile & Load / Strain Testing. Biomechanical testing was performed in accordance with ASTM D3039M - 017 (“Standard Test Method for Tensile Properties of Polymer Matrix Composites”). To simulate surgical fixation, a fiber test cord was looped inside the implant for connection to a mechanical load tester. The load was gradually increased until failure. The implant produced by FFF initially held a peak load (to failure) at approximately 12 N (Newtons), and this peak decreased by more than 30% within 16 weeks of incubation in the culture medium, dropping to 7 - 9 N. In contrast, the prototype implant demonstrated significantly superior performance. The prototype implant initially withstood a tensile load of 1332 N and maintained approximately 1000 N after 16 weeks of incubation in the culture medium. For reference, the tensile strength of the human anterior cruciate ligament (ACL) is approximately 1100 - 1500 N. The prototype implant also exhibited high elasticity, failing at strains exceeding 70% and recovering to its initial shape after cyclic loading, presenting a typical plastic hysteresis stress - strain curve.

[0065] Platelet - Rich Plasma Wick. The prototype implant was immersed in platelet - rich plasma. The implant rapidly absorbed plasma up to approximately 3 times its weight and continued to absorb up to 5 times its weight during the 30 - minute test.

[0066] Bioceramic Coating. For adhesion testing, the ends of the prototype implant were coated with carbonate apatite and β - tricalcium phosphate and then thermogelated at 37°C. The bioceramic coating remained on the implant after hydration.

[0067] Lyophilized Collagen Coating. A complete collagen shell was formed around the prototype implant by immersion in a collagen solution. It was then frozen and lyophilized to form a collagen sponge layer on the fibers. The tensile strength of the prototype implant with the lyophilized collagen shell (under hydrated conditions) was tested to compare with traditional electrospun collagen and polymer sheets. The results are shown in the following table. Notably, compared with samples made of electrospun polymers and lyophilized collagen, the suture retention strength of the prototype implant was approximately 2000 times higher, and the overall strength was approximately 150 times higher. Additionally, in a direct comparison test conducted on the same testing machine, the prototype exceeded the suture retention performance of bovine Achilles tendon. Moreover, the prototype exceeded the suture retention strength of the human supraspinatus tendon reported in the literature. The tensile strength of the prototype was approximately equal to that of the natural rotator cuff tendon.

[0068]

[0069] M - male; F - female; * - interpreted from the graphical dataset

[0070] Conclusion. The technology of the present invention can fabricate implants with fibers that are similar in size and strength to natural tendons and ligaments. They are three orders of magnitude stronger than similar implants made by traditional manufacturing methods.

[0071] The foregoing description and examples merely illustrate the invention and are not intended to limit the invention. Each disclosed aspect and embodiment of the invention can be considered separately or in combination with other aspects, embodiments, and variations of the invention. Moreover, unless otherwise specified, the steps of the methods of the present invention are not limited to any particular order of execution. Modifications to these embodiments will be apparent to those skilled in the art and such modifications incorporate the spirit and substance of the invention. Such modifications are within the scope of the invention.

[0072] Unless the context clearly indicates otherwise, the word "or" as used in this agreement is inclusive and equivalent to "and / or". Thus, for example, the phrase "A or B" means A or B, or both A and B. Similarly, for example, the expression "A, B, or C" means A, B, C, or any combination thereof.

Claims

1. A method for fabricating a microfiber implant, characterized in that, comprising: (a) having a manufacturing apparatus, the manufacturing apparatus comprising: a winding platform having a rotational axis; a feeder head that moves laterally relative to the winding platform; (b) rotating the winding platform about the rotational axis; (c) feeding microfilaments to the feeder head; (d) discharging the microfilaments from the feeder head and advancing the microfilaments toward the winding platform; (e) winding the microfilaments on the winding platform; (f) moving the feeder head laterally relative to the winding platform; and (g) repeating steps (b)-(f) to wind the microfilaments on the winding platform multiple times to obtain a microfiber patch; (h) performing a post-winding treatment on the microfiber patch to obtain the microfiber implant.

2. The method according to claim 1, characterized in that, further comprising performing multiple sweeps of the winding, wherein each sweep of the winding forms a single entangled layer, and the multiple sweeps produce a stack of entangled layers.

3. The method according to claim 2, characterized in that, wherein the number of sweeps is in the range of 3-50.

4. The method according to claim 2, characterized in that, wherein each sweep forms 3-70 turns of microfilaments per centimeter on the winding platform.

5. The method according to claim 1, characterized in that, further comprising heating the winding platform or a portion thereof to form a fused region on the microfiber patch.

6. The method according to claim 1, characterized in that, wherein the feeder head travels laterally relative to the winding platform at a speed of 20-500 mm / min.

7. The method according to claim 1, characterized in that, wherein the microfilaments are discharged from the feeder head at an output rate of 25-800 cm / min.

8. The method according to claim 1, characterized in that, wherein the feeder head is capable of adjusting an angle to change a direction angle at which the microfilaments are discharged toward the winding platform, and the method further comprises adjusting the direction angle of the feeder head during the multiple windings.

9. The method according to claim 1, characterized in that, wherein the post-winding treatment comprises coating the microfiber patch with collagen.

10. The method according to claim 9, characterized in that, wherein the post-winding treatment further comprises freezing and lyophilizing the collagen coating.

11. The method according to claim 1, characterized in that, wherein the post-winding treatment comprises making an opening in the microfiber patch.

12. The method according to claim 11, characterized in that, wherein the opening is a channel passing through the microfiber patch.

13. The method according to claim 1, characterized in that, wherein the microfilaments are advanced by rotational traction from the rotation of the winding platform.

14. A microfiber implant made by the method according to claim 1.

15. A microfiber implant, characterized in that, comprising: Multiple-turn microfilaments, wherein the diameter of the microfilaments is in the range of 5 - 125 μm; A coating, the coating including an adhesive material that bonds the turns of the microfilaments together; A channel, the channel passing through the microfiber implant; Wherein the fiber density of the microfiber implant is in the range of 20 - 750 rows of microfilaments per centimeter on the turns.

16. The microfiber implant according to claim 15, Characterized in that, It further includes a fusion region, in which the turns of the microfilaments are fused together.

17. The microfiber implant according to claim 15, Characterized in that, It has a thickness in the range of 0.1 - 25 mm, a length in the range of 1.0 - 40 cm, and a width in the range of 0.1 - 30 cm.

18. The microfiber implant according to claim 15, Characterized in that, Wherein the adhesive material forms crosslinking bridges between the laterally adjacent rows of microfilaments.

19. The microfiber implant according to claim 15, Characterized in that, Wherein the microfiber implant has a three-dimensional shape.

20. The microfiber implant according to claim 15, Characterized in that, Wherein the adhesive material is freeze-dried collagen.

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