Patent ID: 12185937

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now more particularly toFIGS.4-7B, the inventive system and methods utilize nanofiber material which is incorporated into the suture anchor and deployed into the bone using standard arthroscopic surgical techniques. Once deployed, the material is located between the soft tissue and bone.

FIGS.4and5illustrate the implementation of a soft tissue anchoring system10in accordance with the present invention. What is illustrated is a portion of soft tissue12which is to be attached to a portion of bone14using the anchoring system10. The soft tissue12may comprise a rotator cuff tendon, to be secured to the humerus, as discussed above in conjunction withFIGS.1-3, or the invention is equally applicable to any other site wherein attachment of soft tissue to bone is desired. A bone tunnel16is created in the bone14and a suture anchor18is placed within the bone tunnel16, as shown, using common surgical techniques, which may or may not be arthroscopic. The illustrated suture anchor18comprises a hollow anchor body, having threads20or other suitable structure for engaging adjacent bone forming walls of the tunnel16to fix the anchor18in place within the tunnel. This type of corkscrew suture anchor is well known in the art. Other suitable types of suture anchors may also be employed. The suture anchor also has an eyelet22or other suitable structure for securing suture24to the anchor, which suture extends through the soft tissue12and secured thereto by means of a knot26or other suitable means. Thus, the soft tissue12is secured to the adjacent bone14by extending the free ends of the suture24through the soft tissue12, securing the anchor18within the bone tunnel16, tensioning the suture24until the soft tissue12is approximated to the adjacent bone14, then creating the suture knot26to secure the soft tissue in place. This basic technique is well known in the art.

The present inventive system comprises a member or insert28which is comprised of a nanofiber material. More particularly, the nanofiber material is, in one embodiment, a monophasic nanofiber scaffold, which are known in the art, as described in the prior art references discussed in the Background portion of this application. Alternatively, a multi-phasic nanofiber scaffold, such as disclosed and described in U.S. Published Patent Application No. 2010/0292791 to Lu et al., herein expressly incorporated by reference in its entirety, may be used. The nanofiber scaffold member28extends into the bone tunnel16through the hollow center of the anchor18, and expands outwardly at the bone surface to maximize surface area contact between the tissue and bone.

Material Configuration and Deployment

There are many configurations which the inventive nanofiber member28may assume. Two such alternative examples are illustrated inFIGS.6A-6CandFIGS.7A-7C, respectively. Each configuration shows the material in the deployed state. Prior to deployment of the anchor into the bone, the material is rolled in a cylindrical fashion around the implant inserter shaft and held in place (and protected) by a tubular sheath. This allows the use of traditional arthroscopic surgical techniques to place the implant into the bone. Once the implant is placed into the bone, the sheath is retracted and the nanofiber material is spread out to maximize the surface area contact between the tissue and bone.

Material Orientation

The nanofiber material can be manufactured with the fibers organized in a random orientation (unaligned) or aligned in one direction (aligned). There are three primary reasons why fiber alignment is important when coupled with the suture anchor.a) As shown by Moffat, aligned fibers provide a pathway for faster cell growth and travel. One presently preferred configuration has a scaffold with fibers aligned axially within the anchor in the direction of cell travel from the bone marrow to the bone surface.b) Fiber orientation can be controlled to mimic the tissue being repaired. For example, the rotator cuff (supraspinatus) has linearly oriented fibers. The scaffold material exposed to the supraspinatus may have aligned fibers in the same direction as the tissue, thus promoting faster and more complete tissue ingrowth. Markings on the inserter or anchor may facilitate proper alignment of the material to the tissue.c) Fiber orientation determines the mechanical strength of the scaffold material. Aligned material has high tensile strength in the direction of the fibers and weak tensile strength in the direction perpendicular to the fibers. Unaligned material exhibits tensile strength in between that of aligned material pulled in two perpendicular directions. The material can be constructed and oriented in the anchor in such a way to increase the strength where necessary.
Material Attachment

There are several ways the material may be attached to an implant. For implants pre-loaded with suture, the material may be looped around the same eyelet as the suture or passed around a secondary eyelet. Another method for attachment is mechanically fastening the material to the anchor using a cleat, screw or post. The material may also be pinched between two halves of an implant. The material may be attached to a portion of an implant using a knot or adhesive. The material may also be bonded to the implant with the use of solvent.

As noted above, two exemplary embodiments of the present inventive system are illustrated inFIGS.6A-6C and7A-7C, respectively. In each embodiment, the nanofiber insert28comprises a distal portion or shaft30for attaching the insert28to the anchor18, and a proximal head32. As shown inFIGS.4and5, the insert28, when the suture anchor is deployed, is disposed so that the distal portion30extends through the suture anchor18, as shown. A proximal end of the distal portion30extends proximally of the proximal end of the anchor body, and the head32is disposed at a proximal end of the insert distal portion, as shown.

FIGS.6A-6Cillustrates an embodiment wherein the insert distal portion30comprises a tube of material with strips34cut in the proximal end to allow the material to be deployed and spread out radially, as shown, to form the proximal head32and increase the surface contact between the tissue and bone. The tube comprises the distal portion30which is secured to the implant.FIGS.7A-7Cillustrates an alternative embodiment, wherein the insert28comprises a die-cut sheet material in the deployed condition. The long portions form the distal portion30which is disposed within the implant that is deployed into bone.

Additional Embodiments and Applications

An additional embodiment of the invention is an implant as previously described, with nanofiber material fixed solely to the proximal end (proximal defined as the end of the implant that is adjacent to the soft tissue, and distal defined as the end of the implant farthest in the bone). The nanofiber material covers just the surface area of the proximal end of the implant or possibly extends further proximally and/or radially away from the central axis of the implant.

Another additional embodiment of the invention is an implant as previously described, wherein the nanofiber material is fixed mechanically, with an adhesive, or by solvent bonding.

Yet another additional embodiment of the invention is an implant as previously described wherein the method of attachment of the material to the implant is via the use of a suture tether that is attached to the implant and the material. The material may be either fixed or movable. To enable the material to be moved into position, the suture is configured such that the surgeon pulls on the free end of the suture which moves the material closer to the implant, allowing the surgeon to position the material into a desired location. The position of the material relative to the implant is set prior to insertion of the implant into the bone or after the implant is deployed into the bone. Once the material is in position it is locked in place or reversibly movable. This may also be incorporated into two or more implants to allow the material to be placed in an adjustable location determined by the surgeon on the bone in between two or more implants.

Still another additional embodiment of the invention is an implant as previously described, wherein the nanofiber material is contained internal to the implant, along its central axis. The material extends at or near the distal tip and at, near or beyond the proximal end of the implant.

Another additional embodiment of the invention is an implant as previously described wherein the material may also be contained externally to the implant or within external channels.

Yet another additional embodiment of the invention is two or more implants as previously described with a bridge of nanofiber material strung between each implant. This configuration might best be described as a blanket of nanofiber material anchored at each implant, with the nanofiber material incorporated within or along the exterior of the implants.

Other applications of the invention include, but are not limited to, applications where soft tissue is re-attached surgically or arthroscopically to bone in locations such as knee, shoulder, foot, ankle, elbow, wrist, hand, spine, and hip. Surgical specialties that could utilize the invention include sports medicine, trauma, spine, foot and ankle, hand, hip, and extremities.

Moffat and others have shown that the use of nanofiber scaffolds promote cell attachment and growth in both aligned and unaligned orientations. The present invention improves the ease of use of nanofiber scaffolds for surgeons by pre-attaching the scaffold to a current, state-of-the-art suture anchor that can be implanted using standard arthroscopic procedures.

Arthroscopic surgeons do not want to complicate their surgical procedures. The value of nanofiber scaffolds in sheet form as proposed by Moffat will be substantially diminished due to the fact that surgeons will be reluctant to use a product that requires an open surgical procedure versus an arthroscopic procedure. The present invention facilitates arthroscopic use of nanofiber scaffolds, potentially increasing their value by several fold.

Accordingly, although an exemplary embodiment of the invention has been shown and described, it is to be understood that all the terms used herein are descriptive rather than limiting, and that many changes, modifications, and substitutions may be made by one having ordinary skill in the art without departing from the spirit and scope of the invention, which is to be limited only in accordance with the following claims.