Variable density soft anchors

Abstract

Surgical anchor structures, fixation devices, and methods for manufacturing them, as well as methods for tissue repair, are disclosed. The soft suture anchor has a sheath whose density changes along the length of the sheath. The anchor sheath may have different segments having different densities, which may be provided in a pattern or random manner. The segments having different densities allow for secure fixation of the soft anchor within the bone and attachment of the first tissue to the second tissue.

Description

[[Background Art]]

[0001] The present disclosure relates to the field of surgical operations, and more specifically, to surgical suture structures, preparation methods, and tissue repair for reconstructive surgery. [[Summary of the Invention]]

[0002] A surgical flexible structure, a fixation device, a preparation method, and a tissue repair method are disclosed.

[0003] The surgical structure may comprise a soft anchor sheath having a density that varies along its length. The soft anchor sheath may have an irregular braided, woven, or knitted density pattern, or a combination thereof. The soft anchor sheath can be manufactured with various controlled sheath densities based on a specific application. The surgical structure can create a knotless, self-tensioning, self-locking reinforced repair. The surgical structure may be used for knotless or knotted fixation of a first tissue to a second tissue, for example, fixation of soft tissue to bone.

[0004] A method of tissue repair is also disclosed. The knotless surgical structure can provide fixation between tissues without any knot formation, with fewer passing steps, and increased fixation and soft tissue compression. The soft anchor sheath with variable density allows better bunching or setting of the anchor within bone. The soft anchor sheath with variable density can enable more reproducible setting of the anchor. [[Brief Description of the Drawings]]

[0005] [Figure 1] Figure 1 shows a soft anchor sheath. [Figure 2] Figure 2 shows another soft anchor sheath. [Figure 3] Figures 3 and 4 show schematic steps of tissue repair using the anchor sheath of Figure 1. [Figure 4] Figures 3 and 4 show the schematic steps of tissue repair using the anchor sheath shown in Figure 1. [Figure 5] Figures 5 and 6 show the schematic steps of tissue repair using the anchor sheath shown in Figure 2. [Figure 6] Figures 5 and 6 show the schematic steps of tissue repair using the anchor sheath shown in Figure 2. [Figure 7] Figure 7 shows a prior art soft anchor sheath. [Figure 8] Figures 8 and 9 show schematic steps of tissue repair using the prior art sheath shown in Figure 7. [Figure 9] Figures 8 and 9 show schematic steps of tissue repair using the prior art sheath shown in Figure 7. [Modes for carrying out the invention]

[0006] This disclosure provides surgical fixation devices, structures, methods for manufacturing them, and tissue repair and reconstruction.

[0007] Soft anchor sheaths may have variable density. Setting a soft anchor sheath requires deformation of the sheath within the bone tunnel to fix the sheath in place. By changing the density of the sheath in a particular region, the sheath deforms first in that region, fixing the sheath in the bone in various ways. Variations include changes in sheath density from high pick number (H) to low pick number (L). Versions of the sheath may be, for example, HLH or LHL, or HLHL or LHLH, allowing the sheath to deform and fix to the bone in various ways. When tension is applied to set the sheath, bunching or deformation of the sheath occurs differently in different regions / within different regions.

[0008] Methods for tissue repair using variable-density soft anchors are also disclosed. Exemplary methods include, in particular, (i) varying the density of a soft anchor sheath along the length of the sheath, and (ii) employing the sheath for one or more tissue repair applications. One or more tissue repair applications may include soft tissue repair, orthopedic repair, such as rotator cuff repair, Achilles tendon repair, patellar tendon repair, ACL / PCL reconstruction, hip and shoulder joint reconstruction, etc.

[0009] Referring here to the drawings, similar elements are indicated by similar reference numerals, and Figures 1 and 2 show exemplary anchor structures 100, 200 of the present disclosure (soft anchors 100, 200, soft anchor sheaths 100, 200, sheaths 100, 200, full suture anchors 100, 200, surgical structures 100, 200). Figures 3 to 6 show schematic steps of exemplary anchor bunching 101, 201 (tissue repair 101, 201) using anchor structures 100, 200. Figure 7 shows a prior art soft anchor structure 300. Figures 8 and 9 show schematic steps of a prior art tissue repair 301 using anchor structure 300.

[0010] The anchor structures detailed below are soft anchors formed from a “soft” material, such as suture material, which are inserted into a socket / hole / tunnel in bone and give the ability to bundle together, fold, expand, and / or change shape to secure within the socket / hole / tunnel. In some embodiments, the soft anchor includes a sheath and at least one flexible strand attached to the sheath. The at least one flexible strand may be fixed (attached) to the sheath or slidable. In other embodiments, the soft anchor includes a sheath and a plurality of flexible strands, some or all of which are attached to the sheath as non-slidable, and some or all of which are slidable to the sheath. Soft anchors can be used in a variety of surgical techniques for attaching tissue to bone.

[0011] Figure 1 shows a soft anchor 100 that includes multiple regions / sections 125, 126, 127, etc., along the sheath 12, having varying densities (mass density, M / V).

[0012] The sheath 12 may be in the form of a tubular sleeve or tubular member made from a flexible material such as yarn, fiber, filament, suture, or similar material, or a braid, woven, or knitted structure made from a combination of these materials. In one embodiment, the sheath 12 is constructed from ultra-high molecular weight polyethylene (UHMWPE). In one embodiment, the sheath 12 is constructed from UHMWPE and polyester. In another embodiment, the sheath 12 is constructed from UHMWPE having an elastic component. In another embodiment, the sheath 12 is constructed from a polyester suture material having an elastic component. The elastic component may be elastane. The elastic component may be incorporated into the sheath via braiding, weaving, and / or knitting. In one embodiment, the elastic sheath may include a combination of elastic, polyester, and UHMWPE, all of which are braided within the tubular jacket. In one embodiment, the elastic sheath may essentially consist of elastane, polyester, and UHMWPE. The elastic components provide elasticity, while the other components provide strength and limit the elongation of the suture.

[0013] In one embodiment, the ends of the sheath 12 can be joined together. In one embodiment, the ends of the sheath 12 can be glued together. In one embodiment, the ends of the sheath 12 can be frayed. In one embodiment, the sheath 12 may be a tape such as a suture tape. The sheath 12 may also be any non-tubular structure.

[0014] The soft anchor 100 may include at least one flexible strand 14 passing through at least a portion of the sheath 12. The sheath 12 includes a tubular body extending between opposing ends 18a, 18b. The opposing ends 18a, 18b may be open or closed. The tubular body establishes a hole extending between the opposing ends 18a, 18b. As shown in Figure 1, one or more flexible strands 14 (flexible couplers 14, sutures 14) pass through at least a portion of the hole in the sheath 12. The flexible strands 14 can help bunch the sheath 12 together when the soft anchor 100 is inserted into the bone or fixed on the bone and tension is applied to the flexible strands 14.

[0015] In one embodiment, the flexible strand 14 can pass through an opening 22 (as shown, for example, in Figure 1), which is formed by a tubular body and spaced apart from the opposing ends 18a, 18b of the sheath 12. The flexible strand 14 may be of any length and may include one or more free ends extending to the outside of the sheath 12. This configuration can be used when the opposing ends 18a, 18b are closed ends. Alternatively, the flexible strand 14 can pass directly through the opposing ends 18a, 18b if they are configured as open ends. Additional strands, such as suture passers and / or additional filaments and / or flexible couplers, can be passed through the tubular body of the sheath 12 in the same or different orientations, as desired and depending on the specific surgical procedure being performed. In an additional embodiment, the flexible strand 14 can enter and exit the sheath multiple times, at the same or different locations. For example, the suture thread that comes out of the sheath enters the sheath and comes out again, further assisting the bunching process.

[0016] The flexible strand 14 may be a suture. Non-limiting examples of suitable sutures include FiberWire®, TigerWire®, or FiberChain® sutures, but any type of suture, including cored or coreless sutures, may be used. In another embodiment, the flexible strand 14 may be a suture tape such as FiberTape®. The flexible strand 14 may include any soft, flexible strand material.

[0017] The flexible strand 14 may be attached to the sheath 12 in a non-sliding manner (i.e., not slidable within the hole to change its position relative to the sheath 12), or it may be slidable relative to the sheath 12. Details of the flexible strand 14 attached to the sheath 12 in a non-sliding manner can be found, for example, in U.S. Patent No. 9,622,738, issued on 18 April 2017 and assigned to Arthrex, Inc., the disclosure thereof is incorporated herein by reference in its entirety.

[0018] The soft anchor 100 is configured for use in various soft tissue repairs or fixations and can be fixed intraosseously or on bone to attach tissue (e.g., ligaments, tendons, grafts, etc.) to bone. For example, the soft anchor 100 can be used in connection with various orthopedic repairs, including but not limited to rotator cuff repairs, Achilles tendon repairs, patellar tendon repairs, ACL / PCL reconstructions, and hip and shoulder joint reconstructions. Fixation may be in contact with or on bone.

[0019] The soft anchor 100 is called a “soft” structure because it is formed from a soft material such as thread, fiber, filament, cord, strand, suture, or any combination of such materials. The soft material may be a synthetic material or a natural material, or a combination of synthetic and natural materials, and may be biodegradable or non-biodegradable, and may be elastic or inelastic within the scope of this disclosure. In one non-limiting embodiment, the soft anchor 100 is made solely from a soft suture-based material.

[0020] As detailed below, the soft anchor 100 can be manufactured via knitting structures and / or knitting processes, or a combination of these processes, may or may not include elastic components therein, and may have a variable number of picks throughout, thereby allowing the soft anchor 100 to deform in accordance with the number of picks.

[0021] As shown in Figure 1, the sheath 12 of the soft anchor 100 includes a plurality of segments / portions / regions / lengths having different densities. In a non-limiting embodiment, the sheath 12 comprises a first portion 125 (first segment 125, first length 125, first region 125), a second portion 126 adjacent thereto (second segment 126, second length 126, second region 126), and a third portion 127 further adjacent thereto (third segment 127, third length 127, third region 127). In one embodiment, one of the first, second, and third portions 125, 126, 127 may have a first density (first mass density, first braid pattern density, first picks per inch, first programmable picks per inch (PPI)), and an adjacent portion has a second density (second mass density, second braid pattern density, second picks per inch, second programmable picks per inch (PPI)), wherein the first density is different from the second density.

[0022] One of the first, second, and third portions 125, 126, 127 may be a high density (H) portion, and the other remaining portions are low density (L) portions. In other embodiments, one of the first, second, and third portions 125, 126, 127 may be a low density (L) portion, and the other remaining portions are high density (H) portions. In an exemplary embodiment, L can be about 2 mm, and H can be about 3 mm.

[0023] In one embodiment, portions or segments of the sheath 12 may have an alternating pattern of high-density segments and low-density segments along the length of the sheath. In one embodiment, the high-density and / or low-density segments or portions of the sheath 12 may alternate randomly along the length of the sheath. In yet an additional embodiment, a regular pattern of high-density segments and / or low-density segments may alternate with randomly provided segments (high-density segments and / or low-density segments) along the length of the sheath. In additional embodiments, different segments of the sheath may be provided with two or more different densities, and all of the two or more densities are different. Different segments of the sheath may have different lengths and / or different diameters and / or compositions.

[0024] Figure 1 shows an exemplary embodiment of a sheath 12 of a soft anchor 100 having first and third segments 125, 127 provided as H-density segments and a second segment 126 provided as an L-density segment. In the exemplary embodiment only, L may be approximately 2 mm, and H may be approximately 3 mm.

[0025] Figure 2 shows an exemplary embodiment of a sheath 212 of a soft anchor 200 having first and third segments 225, 227 provided as L-density segments and a second segment 226 provided as an H-density segment.

[0026] While embodiments in Figures 1 and 2 have been described with reference only to three segments or regions of sheaths 12, 112 of different densities, it should be understood that this disclosure is not limited to these illustrative embodiments only. Therefore, this disclosure envisions any number of segments, regions, lengths, and portions of a tubular sheath having at least two different densities in a regular or irregular pattern. The number and length of sections may vary in a regular or irregular pattern along the length of sheaths 12, 112. The number of densities may also vary. Sheaths 12, 112 may comprise any number of segments, all different and having any number of variable densities. The length of the segments may also vary depending on the particular anchor bunching repair.

[0027] The soft anchors 100, 200 may be woven suture structures constructed of twisted and / or braided, knitted, or woven monofilaments parallel to the warp or weft directions. The density behavior can be manipulated by the amount or composition of the fibers braided together (e.g., by adding monofilaments) to create segments of different densities along the length of the sheath. One or more filaments of elastic material such as elastane can be incorporated into the sheath.

[0028] Soft anchors 100, 200 can be constructed such that monofilament and / or elastic material can be deflected, inserted, or removed at desired locations, regardless of the suture configuration which creates high-density and low-density segments within the same suture braid / sheath. Soft anchors 100, 200 can be fabricated as a single-piece structure.

[0029] Tubular sheaths 12, 112 with circular and / or elliptical cross-sections can be manufactured via braiding, weaving, and / or knitting processes using monofilaments and / or elastic components incorporated into the remaining carriers (bundles). In exemplary embodiments, the sheaths 12, 112 may include a single monofilament incorporated within 15 carriers to form one or more H-density segments as part of the sheath. The sheaths 12, 112 may also include elastic components.

[0030] Figures 3 and 4 schematically illustrate soft anchors 100 that fix a first tissue 80 to a second tissue 90 as part of anchor bunching 101 (surgical repair 101). Figures 3 and 4 show soft anchors 100 inserted into the second tissue 90 (e.g., cancellous bone) through the first tissue 80 (e.g., cortical bone) as part of the repair 101. The sheath 12 fixes to the first tissue 80 (bone 80) so that density changes in the sheath material allow for increased bunching and deformation within the bone hole, socket, or tunnel, and the sheath allows for fixation in various ways to enhance overall fixation. A flexible coupler 14 can pass through the tissue and fix it to the bone.

[0031] Similarly, Figures 5 and 6 schematically illustrate a soft anchor 200 that fixes a first tissue 80 (e.g., soft tissue) to a second tissue 90 (e.g., bone) as part of anchor bunching 201 (surgical repair 201). The sheath 112 is fixed within the second tissue 90 (bone 90) so that density changes in the sheath material allow for increased bunching and deformation within the bone hole, socket, or tunnel, and the sheath is fixed in various ways to enhance overall fixation. A flexible coupler 14 can pass through the tissue and fix it to the bone.

[0032] The flexible couplers 14 of the repairs 101, 201 may be used to attach the soft tissue 80 to the bone 90 by passing the flexible coupler through or around the soft tissue, forming at least one adjustable, flexible, continuous, knotless, tensionable loop around or through the soft tissue 80. One or more flexible couplers 14 and optional shuttle strands may extend through holes in the sleeves 12, 112 in similar or different directions and / or orientations and / or positions. The flexible tubular sleeves 12, 112 having flexible couplers and shuttle strands may be fixed in or on the bone, and the flexible strands may pass over the soft tissue (rotator cuff) and be fixed to the bone to approximate the soft tissue to the bone. For more details on exemplary soft suture anchors having a soft anchor sleeve (sheath, or tubular member) and a flexible shuttle strand, see, for example, U.S. Patent No. 10,849,734, entitled “Methods of Tissue Repairs,” issued 1 December 2020, the disclosure of which is incorporated herein by reference in its entirety.

[0033] The flexible coupler 14 may be further attached to one or more fixing devices, such as any anchor, for example, a knotted anchor, a knotless anchor, or a full suture anchor, or any device that provides secure attachment and fixation of the soft tissue 80 to the bone 90. The fixing device may be a knotless anchor, such as a two-piece Arthrex PushLock® anchor disclosed in U.S. Patent No. 7,329,272, or an Arthrex SwiveLock® anchor disclosed in U.S. Patents No. 8,012,174 and U.S. Patent No. 9,005,246, both of which are fully incorporated herein by reference. The fixing device may also be another full suture soft anchor, such as the soft anchors 100, 200 detailed above. The flexible coupler 14 may essentially consist of elastic suture.

[0034] Another exemplary fastening device is a soft anchor, or "knotless" anchor. A soft anchor (soft knotless anchor, or knotless soft anchor) comprises a soft anchor sleeve (sheath, or tubular member) having two open ends and at least two flexible shuttle strands extending through the soft anchor sleeve (sheath).

[0035] Figures 7-9 show a prior art soft anchor 300 that fixes a first tissue 80 (e.g., soft tissue) to a second tissue 90 (e.g., bone) as part of a prior art surgical repair 301. The sheath 212 fixed within the second tissue 90 (bone 90) has no density changes within the sheath material, and therefore bunching and deformation are minimal compared to the repairs 101, 201 detailed above.

[0036] Methods for manufacturing soft anchor sheaths having varying densities and / or elasticity are also disclosed. An exemplary method for manufacturing soft anchor sheaths 12, 112 includes the step of incorporating monofilaments and optionally elastic components into the sheath via braiding, weaving, and / or knitting to form regular or irregular braided density patterns within the sheaths 12, 112. The method may further include the step of attaching one or more flexible strands 14 to the soft anchor sheaths 12, 112. One or more flexible strands 14 may be elastic.

[0037] A method of soft tissue reconstruction includes attaching soft tissue 80 to bone 90 using at least one soft anchor 100, 200. The method may include forming at least two sections of different densities along the length of the sheaths 12, 112 of the soft anchors 100, 200, attaching at least one flexible coupler 14 to the sheaths 12, 112, and fixing the soft anchors 100, 200 within the bone. The method may also include fixing the soft anchors 100, 200 within the bone 90 so that at least two sections of different densities bunch in different ways within the bone 90, and attaching the soft tissue to the bone by passing at least one flexible coupler 14 through or around the soft tissue 80. The method may further include forming at least one adjustable, flexible, continuous, knotless, tensionable loop around or through the soft tissue 80 using at least one flexible coupler 14. The method may further include fixing at least one flexible coupler 14 to a fixation device. The fixation device may be a knotless anchor. The fixation device may be a hard-body anchor. The fixation device may be a soft anchor. At least one flexible coupler 14 may essentially consist of an elastic suture. The soft tissue 80 may be the rotator cuff. Multiple soft anchors 100, 200 may be used for soft tissue repairs such as rotator cuff repairs.

[0038] The structures and methods of this disclosure provide increased and consistent pressure for longer-lasting retention on organizations.

[0039] The structures of this disclosure are applicable to any tissue repair and surgical procedure, such as rotator cuff repair, Achilles tendon repair, patellar tendon repair, ACL / PCL reconstruction, hip and shoulder joint reconstruction, and the use of elastic sutures used within or with suture anchors. The surgical structures and repair methods of this disclosure can be used, in particular, for use with suture anchors (e.g., PushoLock® and / or SwiveLock® suture anchors) or for knotless arthroscopic suture repairs (e.g., knotless single-row rotator cuff repair, or knotless SpeedBridge® repairs using only a suture threading step).

[0040] Developed by Arthrex, Inc. and disclosed in U.S. Patent No. 8,012,174 (the disclosure of which is incorporated herein by reference in its entirety), the exemplary SutureBridge® tendon repair technique consists of a knotted medial row constructed with two threaded suture anchors, combined with knotless lateral fixation using two Arthrex PushLock® structures. The structures enhance footprint compression and promote tendon-to-bone healing with minimal knotting.

[0041] The exemplary SpeedBridge® technology, developed by Arthrex, Inc. and disclosed in U.S. Patent No. 9,005,246 (the entire disclosure of which is incorporated herein by reference), uses a threaded swivel anchor that, when combined with either structure 100 or 200, can produce a knotless, fast, and secure SutureBridge® structure involving only two suture-threading steps.

[0042] A method of soft tissue reconstruction includes attaching soft tissue 80 to bone 90 using at least one surgical structure 100, 200. The method may further include fixing the surgical structures 100, 200 to bone 90 and fixing at least one flexible coupler 14 to soft tissue 80. The surgical structures 100, 200 may be integral structures containing elastic material. The flexible coupler 14 may contain elastic material. The method may further include attaching the flexible coupler 14 to a fixation device. The fixation device may be a knotless or knotted anchor.

[0043] The flexible coupler 14 may be formed from a high-strength suture material such as FiberWire® suture, sold by Arthrex, Inc. (Naples, Florida) and described in U.S. Patent No. 6,716,234 (the disclosure of which is incorporated herein by reference). FiberWire® suture is formed from an advanced high-strength fibrous material, namely ultra-high molecular weight polyethylene (UHMWPE), sold under the trademarks Spectra® (Honeywell International Inc. (Colonial Heights, Virginia)) and Dyneema® (DSM NV, Netherlands, Heerlen), and optionally braided with at least one other elastic fiber, natural or synthetic, to form the length of the suture material. The flexible coupler 14 may also include suture tapes such as FiberTape® suture tape (disclosed in U.S. Patent No. 7,892,256, the entire disclosure of which is incorporated herein by reference), or collagen tape, or a wide range of “tape-like” materials, or combinations thereof.

[0044] The flexible coupler 14 may essentially consist of a suture material and elastane, or essentially consist of a combination of the suture material, elastane, and other materials, such as long-chain synthetic polymers like polyester and nylon, or materials such as PET, silk nylon, or absorbable polymers, or coating materials (such as wax, silk, or silicone products). The flexible coupler 14 may consist of strands having cross-sections of various shapes and geometric shapes, including, among other things, circular, elliptical, rectangular, or flat, or combinations of such shapes and geometric shapes. In one embodiment, at least one flexible coupler 14 may be provided as a braided, knitted, or woven suture.

[0045] Some or all of the soft anchors 100, 200, including the sheaths 12, 112 and the flexible coupler 14, may also be coated and / or supplied in different colors. In one embodiment, some (or all) of the sheaths 12, 112 and the flexible coupler 14 may be coated (partially or completely) with wax (beeswax, petroleum wax, polyethylene wax, or others), silicone (Dow Corning silicone fluid 202A, or others), silicone rubber (Nusil Med 2245, Nusil Med 2174 including a binding catalyst, or others), PTFE (Teflon, Hostaflon, or others), PBA (polybutyrate), ethylcellulose (Filodel), or other coatings, for example, to improve the lubricity, flexibility, ease of handling, or wear resistance of the structure.

[0046] Some or all of the sheaths 12, 112 and / or the flexible coupler 14 may also have colored tracing strands or otherwise be visually contrasted with other parts of the structure, for example, remaining in a simple solid color or displaying a different tracing pattern. Various structural elements of the surgical structure may be visually coded to facilitate the identification and handling of the leg of the suture. Easy identification of the suture in situ is advantageous in surgical procedures.

[0047] The term “high-strength suture” is defined as any stretched, flexible member, the choice of material and size determined by the specific application. For illustrative purposes only and without limitation, the term “suture” as used herein may be a cable, filament, thread, wire, fabric, or any other flexible member suitable for fixing tissues within the body.

Claims

1. A soft anchor comprising a tubular sheath having at least two different mass densities along its length.

2. The soft anchor according to claim 1, wherein the tubular sheath has at least one segment having a first mass density and at least another segment having a second mass density, wherein the first mass density is different from the second mass density.

3. The soft anchor according to claim 2, wherein the tubular sheath has two segments having the first mass density and one segment having the second mass density.

4. The soft anchor according to claim 2, further comprising a first plurality of segments having the first mass density and a second plurality of segments having the second mass density, wherein the first plurality of segments and the second plurality of segments form a pattern along the length of the tubular sheath.

5. The soft anchor according to claim 1, wherein the tubular sheath comprises a braided, woven, or knitted monofilament using additional filaments.

6. The soft anchor according to claim 1, further comprising at least one flexible coupler that passes through the tubular sheath at least once.

7. The soft anchor according to claim 6, wherein the at least one flexible coupler enters the tubular sheath in a first position, extends within the tubular sheath, and exits the tubular sheath in a second position, the second position being different from the first position.

8. The soft anchor according to claim 7, wherein the first position is the first open end of the tubular sheath, and the second position is the second open end of the tubular sheath.

9. The soft anchor according to claim 7, wherein the first position is spaced apart from the open end of the tubular sheath.

10. The soft anchor according to claim 6, wherein at least one region of the flexible coupler is attached to a fixed device.

11. The soft anchor according to claim 10, wherein the fixing device is a knotless suture anchor.

12. The soft anchor according to claim 6, wherein the soft anchor is a full suture anchor and the flexible coupler is a circular suture.

13. The soft anchor according to claim 1, wherein the tubular sheath is essentially made of polyester and UHMWPE.

14. The soft anchor according to claim 1, wherein the tubular sheath is essentially made of polyester, UHMWPE, and elastane.

15. The soft anchor according to claim 1, wherein the tubular sheath is elastic.

16. The soft anchor according to claim 1, wherein the tubular sheath is inelastic.

17. The soft anchor according to claim 1, wherein the soft anchor is manufactured as an integrated structure.

18. A method for soft tissue repair, comprising attaching soft tissue to bone using at least one soft anchor sheath having different mass densities.

19. At least one flexible coupler is attached to the soft anchor sheath, The soft anchor sheath is fixed to the bone, Fixing at least one of the flexible couplers to the soft tissue, The method according to claim 18, further comprising:

20. The method according to claim 19, wherein the soft anchor sheath has at least two distinct segments having different mass densities.

21. The method according to claim 20, wherein when the soft anchor sheath is fixed to the bone, the soft anchor sheath deforms differently in the at least two distinct segments.

22. The method according to claim 19, wherein the at least two distinct segments have different lengths.

23. The method according to claim 18, wherein the material of the soft anchor sheath essentially consists of polyester and UHMWPE.

24. The method according to claim 18, wherein the soft tissue is the rotator cuff.

25. A method of tissue repair comprising attaching a first tissue to a second tissue using at least one soft anchor sheath having different densities along its length.

26. The method according to claim 25, wherein the first tissue is cortical bone and the second tissue is cancellous bone.

27. The method according to claim 25, wherein the soft anchor sheath has at least two separate segments having different densities.

28. The method according to claim 27, wherein one of the at least two separate segments has a length of about 2 mm and the other of the at least two separate segments has a length of about 3 mm.

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