Patent Publication Number: US-2021177609-A1

Title: Anchoring device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/947,970, filed Dec. 13, 2019, the contents of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Current coupling devices for medical implants, such as for femoral stems used in total hip arthroplasty, are inserted into the medullary cavity of a femur and are coupled to the femur either by fasteners, pins, adhesive, or friction fit. However, certain coupling techniques can cause adverse reactions, which can lead to complications and/or longer recovery times for the patient. Some coupling techniques can also allow the implant to become loose within the medullary cavity over time. 
     Furthermore, current coupling devices can be difficult to replace during re-surgery, which can cause damage to the bone of the patient during removal and reimplantation. 
     Thus, a need exists for an implant coupling device that is less susceptible to adverse reactions, will stay rigidly coupled to a bone over time, and can be removed and reimplanted during re-surgery without damaging the bone of the patient. 
     SUMMARY 
     Various implementations include an anchoring device. The device includes a tubular body and at least one anchor. The tubular body has a longitudinal axis, an outer surface, and an inner surface opposite and radially spaced apart from the outer surface. An axially extending section of the body defines at least one opening extending from the outer surface to the inner surface. The at least one opening has a first axial end and a second axial end opposite and spaced apart from each other along the longitudinal axis. The at least one anchor extends along the opening between the first axial end and the second axial end of the opening. The at least one anchor includes a shape memory material. The at least one anchor is movable from a retracted position to an extended position by either increasing the temperature of the anchor above an austenite finishing temperature or decreasing the temperature of the anchor below a martensite finishing temperature. The anchor has a smaller radius of curvature in a plane that includes the longitudinal axis in the extended position than in the retracted position. 
     In some implementations, the at least one anchor further includes a resilient member that is biased toward the extended position and urgable toward the retracted position. The shape memory material of the at least one anchor urges the resilient member toward the retracted position when the anchor is above the austenite finishing temperature and allows the resilient member to move toward the extended position when the anchor is below the martensite finishing temperature. 
     In some implementations, the body includes a shape memory material. In some implementations, the body and the anchor are integrally formed. In some implementations, the body includes a single piece of formed shape memory material foil. 
     In some implementations, the device further includes a tubular inner sleeve defining the at least one anchor. The inner sleeve is configured to be disposed relative to the body such that the at least one anchor is extendable through the at least one opening in the extended position. In some implementations, the inner sleeve includes a single piece of formed shape memory material foil. 
     In some implementations, the body includes a material with a higher modulus of elasticity than the at least one anchor. In some implementations, the body includes a porous material. In some implementations, the body includes a biocompatible material. 
     In some implementations, the at least one anchor extends parallel to the longitudinal axis. In some implementations, the at least one anchor extends circumferentially as it extends in an axial direction such that the anchors extend helically around the body of the device. 
     In some implementations, a cross-section of the body as viewed in a plane perpendicular to the longitudinal axis is circular. 
     In some implementations, the body includes two axially extending sections, and each of the two axially extending sections defines two or more circumferentially spaced openings. 
     In some implementations, the anchor is curved radially outwardly along the axial direction in the extended position. In some implementations, the anchor is not curved along the axial direction in the retracted position. 
     In some implementations, the axially extending section of the body defines at least three circumferentially spaced openings and the device includes at least three anchors. 
     In some implementations, the shape memory material is NiTi. 
     In some implementations, one of the inner surface and the outer surface includes a coating comprising polyethylene terephthalate (“PET”). 
     Various other implementations include a method for creating an anchoring device. The method includes (1) forming a material into a tubular body, the body having a longitudinal axis, an outer surface, and an inner surface opposite and radially spaced apart from the outer surface; (2) defining at least one opening in an axially extending section of the body, wherein each of the at least one opening extends from the outer surface to the inner surface, the at least one opening having a first axial end and a second axial end opposite and spaced apart from each other along the longitudinal axis; (3) forming at least one anchor extending along the opening between the first axial end and the second axial end of the opening, wherein the at least one anchor comprises a shape memory material; and (4) increasing the temperature of the at least one anchor above a shape setting temperature of the shape memory material to set either an extended position or a retracted position of the at least one anchor. The at least one anchor is movable from the extended position to the retracted position by either increasing the temperature of the anchor above an austenite finishing temperature or decreasing the temperature of the anchor below the martensite finishing temperature. The anchor has a smaller radius of curvature in a plane that includes the longitudinal axis in the extended position than in the retracted position. 
     In some implementations, the method further includes deforming the at least one anchor into the extended position prior to increasing the temperature of the at least one anchor above the shape setting temperature, and the method further includes decreasing the temperature of the at least one anchor below a martensite finishing temperature of the shape memory material and deforming the at least one anchor from the extended position to the retracted position. 
     In some implementations, increasing the temperature of the at least one anchor above a shape setting temperature of the shape memory material sets the retracted position of the at least one anchor, and the at least one anchor further includes a resilient member that is biased toward the extended position and urgable toward the retracted position. The shape memory material of the at least one anchor urges the resilient member toward the retracted position when the anchor is above the austenite finishing temperature and allows the resilient member to move toward the extended position when the anchor is below the martensite finishing temperature. 
     In some implementations, the body comprises a shape memory material. In some implementations, the body and the anchor are integrally formed. In some implementations, the body includes a single piece of formed shape memory material foil. 
     In some implementations, wherein a tubular inner sleeve defines the at least one anchor, and the method further includes, after deforming the at least one anchor from the extended position to the retracted position, disposing the inner sleeve relative to the body such that the at least one anchor is extendable through the at least one opening in the extended position. In some implementations, the inner sleeve includes a single piece of formed shape memory material foil. 
     In some implementations, the body includes a material with a higher modulus of elasticity than the at least one anchor. In some implementations, the body includes a porous material. In some implementations, the body includes a biocompatible material. 
     In some implementations, the at least one anchor extends parallel to the longitudinal axis. In some implementations, the at least one anchor extends circumferentially as it extends in an axial direction such that the anchors extend helically around the body of the device. 
     In some implementations, a cross-section of the body as viewed in a plane perpendicular to the longitudinal axis is circular. 
     In some implementations, the body includes two axially extending sections, and two or more circumferentially spaced openings are defined in each of the two axially extending sections. 
     In some implementations, the anchor is curved radially outwardly along the axial direction in the extended position. In some implementations, the anchor is not curved along the axial direction in the retracted position. 
     In some implementations, the axially extending section of the body defines at least three circumferentially spaced openings and the device includes at least three anchors. 
     In some implementations, the shape memory material is NiTi. 
     In some implementations, one of the inner surface and the outer surface includes a coating comprising polyethylene terephthalate (“PET”). 
     Various other implementations include a method of coupling an anchoring device to an object. The method includes (1) obtaining an anchoring device, such as the anchoring device described above; (2) disposing an object having a longitudinal axis relative to the anchoring device such that at least a portion of one of the object and the anchoring device is disposed within the other of the anchoring device and the object; and (3) either increasing the temperature of the anchor above the austenite finishing temperature or decreasing the temperature of the anchor below the martensite finishing temperature to move the anchor from the retracted position to the extended position. The anchor abuts the object in the extended position. 
     In some implementations, the at least one anchor further includes a resilient member that is biased toward the extended position and urgable toward the retracted position. The shape memory material of the at least one anchor urges the resilient member toward the retracted position when the anchor is above the austenite finishing temperature and allows the resilient member to move toward the extended position when the anchor is below the martensite finishing temperature. 
     In some implementations, the body includes a shape memory material. In some implementations, the body and the anchor are integrally formed. In some implementations, the body includes a single piece of formed shape memory material foil. 
     In some implementations, a tubular inner sleeve defines the at least one anchor, and the inner sleeve is configured to be disposed relative to the body such that the at least one anchor is extendable through the at least one opening in the extended position. In some implementations, the inner sleeve includes a single piece of formed shape memory material foil. 
     In some implementations, the body includes a material with a higher modulus of elasticity than the at least one anchor. In some implementations, the body includes a porous material. In some implementations, the body includes a biocompatible material. 
     In some implementations, the at least one anchor extends parallel to the longitudinal axis. In some implementations, the at least one anchor extends circumferentially as it extends in an axial direction such that the anchors extend helically around the body of the device. 
     In some implementations, a cross-section of the body as viewed in a plane perpendicular to the longitudinal axis is circular. 
     In some implementations, the body includes two axially extending sections, and two or more circumferentially spaced openings are defined in each of the two axially extending sections. 
     In some implementations, the anchor is curved radially outwardly along the axial direction in the extended position. In some implementations, the anchor is not curved along the axial direction in the retracted position. 
     In some implementations, the axially extending section of the body defines at least three circumferentially spaced openings and the device includes at least three anchors. 
     In some implementations, the shape memory material is NiTi. 
     In some implementations, one of the inner surface and the outer surface includes a coating comprising polyethylene terephthalate (“PET”). 
     In some implementations, the object includes a bone. In some implementations, the anchoring device is disposed within a medullary cavity of the bone. 
     In some implementations, the object includes a pipe. In some implementations, the pipe is disposed within the anchoring device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Example features and implementations are disclosed in the accompanying drawings. However, the present disclosure is not limited to the precise arrangements and instrumentalities shown. 
         FIG. 1  is a perspective view of an anchoring device, according to one implementation. 
         FIG. 2  is a perspective view of a first step in the manufacturing of the anchoring device of  FIG. 1 , according to one implementation. 
         FIG. 3A  is a perspective view of a first step of coupling the anchoring device of  FIG. 1  to an object, according to one implementation. 
         FIG. 3B  is a perspective view of a second step of coupling the anchoring device of  FIG. 1  to an object, according to the implementation of  FIG. 3A . 
         FIG. 4  is a perspective view of an anchoring device, according to another implementation. 
         FIG. 5A  is an exploded perspective view of an anchoring device, according to another implementation. 
         FIG. 5B  is a perspective view of a retracted position of the anchoring device of  FIG. 5A . 
         FIG. 5C  is a perspective view of an extended position of the anchoring device of  FIG. 5A . 
         FIG. 6A  is a perspective view of a retracted position of an anchoring device, according to another implementation. 
         FIG. 6B  is a perspective view of an extended position of the anchoring device of  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION 
     The devices, systems, and methods disclosed herein provide for an anchoring device with extendable anchors. The anchors include a shape memory material that is configured to move the anchors to an extended position when the temperature of the device is either increased above the austenite finishing temperature or decreased below the martensite finishing temperature of the shape memory material. An object, such as a bone or a pipe, can be disposed relative to the anchoring device such that when the anchors are extended, the anchors rigidly abut the surfaces of the object to couple the anchoring device to the object. The device can also be used for quick changing of tires, as an axle of a vehicle, paper roll dispensers, or any other situation where coupling and uncoupling of objects is desired. The device can also include multiple coupling portions for coupling multiple objects together. 
     When the anchoring device is incorporated into a medical implant and the anchoring device is inserted into the medullary cavity of a bone, the device can be heated to cause the anchors to extend and unobtrusively and rigidly couple the implant to the bone. In some implementations, the anchors move to the extended position when the temperature of the device is increased above the austenite finishing temperature, and the austenite finishing temperature is below the patient&#39;s body temperature. The device can be kept below the austenite finishing temperature until the implant is disposed within the medullary cavity of the bone, and the patient&#39;s internal body temperature causes the anchors to move to the extended position. 
     When the devices, systems, and methods disclosed herein are used as a coupler for medical implants, the device can be easily removed and reimplanted during re-surgery without damaging the bone of a patient. The temperature of the shape memory material anchors can be either be increased or decreased to release the rigid, extended position of the anchors to allow the implant to be uncoupled from the bone. 
     Various implementations include an anchoring device. The device includes a tubular body and at least one anchor. The tubular body has a longitudinal axis, an outer surface, and an inner surface opposite and radially spaced apart from the outer surface. An axially extending section of the body defines at least one opening extending from the outer surface to the inner surface. The at least one opening has a first axial end and a second axial end opposite and spaced apart from each other along the longitudinal axis. The at least one anchor extends along the opening between the first axial end and the second axial end of the opening. The at least one anchor includes a shape memory material. The at least one anchor is movable from a retracted position to an extended position by either increasing the temperature of the anchor above an austenite finishing temperature or decreasing the temperature of the anchor below a martensite finishing temperature. The anchor has a smaller radius of curvature in a plane that includes the longitudinal axis in the extended position than in the retracted position. 
     Various other implementations include a method for creating an anchoring device. The method includes (1) forming a material into a tubular body, the body having a longitudinal axis, an outer surface, and an inner surface opposite and radially spaced apart from the outer surface; (2) defining at least one opening in an axially extending section of the body, wherein each of the at least one opening extends from the outer surface to the inner surface, the at least one opening having a first axial end and a second axial end opposite and spaced apart from each other along the longitudinal axis; (3) forming at least one anchor extending along the opening between the first axial end and the second axial end of the opening, wherein the at least one anchor comprises a shape memory material; and (4) increasing the temperature of the at least one anchor above a shape setting temperature of the shape memory material to set either an extended position or a retracted position of the at least one anchor. The at least one anchor is movable from the extended position to the retracted position by either increasing the temperature of the anchor above an austenite finishing temperature or decreasing the temperature of the anchor below the martensite finishing temperature. The anchor has a smaller radius of curvature in a plane that includes the longitudinal axis in the extended position than in the retracted position. 
     Various other implementations include a method of coupling an anchoring device to an object. The method includes (1) obtaining an anchoring device, such as the anchoring device described above; (2) disposing an object having a longitudinal axis relative to the anchoring device such that at least a portion of one of the object and the anchoring device is disposed within the other of the anchoring device and the object; and (3) either increasing the temperature of the anchor above the austenite finishing temperature or decreasing the temperature of the anchor below the martensite finishing temperature to move the anchor from the retracted position to the extended position. The anchor abuts the object in the extended position. 
       FIGS. 1-3B  show an example of an anchoring device  100  according to one implementation. As seen in  FIG. 1 , the anchoring device  100  includes a tubular body  110  and multiple anchors  132 . The tubular body  110  has a longitudinal axis  112 , an outer surface  114 , and an inner surface  116  opposite and radially spaced apart from the outer surface  114 . The cross-section of the body  110  as viewed in a plane perpendicular to the longitudinal axis  112  is circular, but in other implementations, the cross section of the body can be a triangle, a rectangle, a pentagon, a hexagon, an octagon, or any other desired shape. The body  110  includes two axially extending sections  118  that define a series of openings  120 . Each of the openings  120  is defined by parallel slits  122  that extend parallel to the longitudinal axis  112  and extend from the outer surface  114  to the inner surface  116  of the body  110 . Each of the openings  120  has a first axial end  124  and a second axial end  126  opposite and spaced apart from the first axial end  124  along the longitudinal axis  112 . 
     An anchor  132  extends along each of the openings  120 . Each anchor  132  includes a first anchor end  134  and a second anchor end  136  opposite and spaced apart from the first anchor end  134 . The first anchor end  134  is coupled to the first axial end  124  of the opening  120 , and the second anchor end  136  is coupled to the second axial end  126  of the opening  120 . 
     Because the parallel slits  122  defining each of the openings  120  extend parallel to the longitudinal axis  112 , each of the anchors  132  extending from the first axial ends  124  to the second axial ends  126  of the openings  120  also extend parallel to the longitudinal axis  112 . However, in other implementations, the parallel slits defining each of the openings extend circumferentially as they extend in the axial direction of the body. Thus, in these implementations, each of the anchors extending from the first axial ends to the second axial ends of the openings also extends circumferentially as it extends in the axial direction of the body such that the anchors extend helically around the body of the device. In other implementations, the anchors can be designed to extend in any direction to allow for better coupling to specific surfaces. 
     Although the device  100  shown in  FIGS. 1-3B  includes two axially extending sections  118  that define openings  120 , in other implementations, the device can include only one, or more than two, axially extending sections. The device  100  shown in  FIGS. 1-3B  includes three openings  120  and anchors  132  in each of the two axially extending sections  118 , but in other implementations, the device can include any number of openings and anchors in each of the axially extending sections. 
     The body  110  and the anchors  132  are both made of Nitinol (“NiTi”). NiTi is a shape memory material, which allows the anchors  132  to be articulated from a retracted position to an extended position by increasing the temperature of the anchor  132  above an austenite finishing temperature. In the extended position, the anchor  132  has a smaller radius of curvature in a plane that includes the longitudinal axis  112  than in the retracted position. 
     The body  110  and the anchors  132  of the device  100  shown in  FIGS. 1-3B  are integrally formed. However, in some implementations, the body and the anchors are separately formed and are coupled to each other. 
       FIG. 2  show the steps for manufacturing the device  100  shown in  FIG. 1 . A sheet of NiTi is first cooled such that the temperature of the sheet of NiTi is below the martensite finishing temperature. In some implementations, the martensite finishing temperature may be higher than room temperature such that the NiTi sheet is already below the martensite finishing temperature and no cooling is necessary. While the NiTi sheet is at or below the martensite finishing temperature of the shape memory material, the NiTi material is malleable and can be formed into a shape. 
     The sheet of NiTi is then formed into a tubular body  110  by wrapping the NiTi sheet around a cylindrical form  180 . Slits  122  are cut through the NiTi sheet of the body  110  to define at least one opening  120  in an axially extending section  118  of the body  110 , as shown in  FIG. 2 . Each of the openings  120  is defined by parallel slits  122  that extend parallel to the longitudinal axis  112  and extend from the outer surface  114  to the inner surface  116  of the body  110 . The remaining portion of the NiTi sheet between each pair of adjacent slits  122  of the opening  120  define an anchor  132  that extends along the opening  120  between the first axial end  124  and the second axial end  126  of the opening  120 . While the device  100  is still at, or below, a martensite finishing temperature of the shape memory material, each anchor  132  is deformed into an extended position in which the anchors  132  are curved radially outwardly along the axial direction, as shown in  FIG. 2 . 
     The device  100  is then heated (e.g., in an oven or kiln) such that the temperatures of the anchors  132  are above the shape setting temperature of the NiTi material. Once the shape setting temperature of the shape memory material has been reached, the austenite, extended position of the anchors  132  of the device  100  are set. The device  100  is then allowed to cool (either actively or passively at room temperature) such that the temperature of the anchors  132  decrease below the martensite finishing temperature of the NiTi material. Once the temperature of the anchors  132  of the device  100  decrease below the martensite finishing temperature, the NiTi material becomes malleable enough to allow the anchors  132  to be deformed back from the extended position to the retracted position, as shown in  FIG. 1 , in which the anchors  132  are not curved along the axial direction. 
       FIGS. 3A and 3B  show the device  100  of  FIGS. 1-3B  being coupled to an object  150 , such as a femur. However, in other implementations, the device shown in  FIGS. 1-3B  can be coupled to any partially or fully hollow object. To couple the anchoring device  100  to one or more objects  150  (e.g., a medullary cavity of a bone or the inside of a pipe), the temperatures of the anchors  132  of the device  100  are adjusted to below, or ensured that the temperatures are below, the martensite finishing temperature such that the anchors  132  of the device  100  are in the retracted position. Then, at least a portion of the anchoring device  100  is disposed inside the opening  152  of one object  150 , as shown in  FIG. 3A . If the device  100  is to be coupled to two objects  150 , each end of the anchoring device  100  is disposed within an opening  152  in each object  150 . In both instances, the axially extending sections  118  on either end of the body  110  are disposed within the opening(s)  152  of the object(s)  150  such that the anchors  132  can contact the walls of the opening(s)  152 . 
     Next, the temperatures of the anchors  132  of the device  100  are increased above the austenite finishing temperature. When the temperature of the device  100  reaches the austenite finishing temperature, the shape memory property of the NiTi anchors reverts the anchors  132  back from the retracted position to their previously shape-set, extended position (i.e., the austenite position), as shown in  FIG. 3B . The anchors  132  in their extended positions abut the inner walls of the opening  152  of the object  150 . In the austenite state, the NiTi material of the anchors  132  becomes much more rigid relative to the NiTi material when in the martensite state of the retracted position. Thus, when the anchors  132  extend radially outwardly to abut the wall of the opening  152  in the object  150  while in the extended position, the rigidity of the anchors  132  locks the anchoring device  100  into place with a friction fit. When each end of the device  100  is disposed in separate objects  150 , the anchoring device  100  can be used to couple the separate objects  150  together. 
       FIG. 4  shows another implementation of an anchoring device  400 . The device  400  shown in  FIG. 4  is similar to the anchoring device  100  shown in  FIGS. 1-3B , but the anchoring device  400  shown in  FIG. 4  includes anchors  432  that extend radially inwardly in the extended position. Similar reference numbers are used for the anchoring device  400  shown in  FIG. 4  for features that are similar to those of the anchoring device  100  shown in  FIGS. 1-3B . The extended position and retracted position are set in a similar way as described above for the anchoring device  100  shown in  FIGS. 1-3B , but with the anchors  432  being deformed radially inwardly in the extended position shown in  FIG. 4 . 
     The device  400  shown in  FIG. 4  can be coupled to one or more objects  450  by disposing at least a portion of the one or more objects  450  inside the tubular body  410  of the device  400  while the device  400  is below the martensite finishing temperature. If the device  400  is to be coupled to two objects  450 , a portion of each of the objects  450  is disposed within an end of the anchoring device  400 . Then, the temperatures of the anchors  432  of the device  400  are increased above the austenite finishing temperature such that the NiTi anchors  432  move from the retracted position to their previously shape-set, extended position shown in  FIG. 4 . The anchors  432  in their radially inwardly extended positions abut the outer walls of the object(s)  450  to rigidly lock the anchoring device  400  into place with a friction fit. 
       FIGS. 5A-5C  show another implementation of an anchoring device  500 . Unlike the anchoring device  100  shown in  FIGS. 1-3B , the anchoring device  500  shown in  FIGS. 5A-5C  includes a body  510  that is separately formed from the anchors  532 . Similar reference numbers are used for the anchoring device  500  shown in  FIGS. 5A-5C  for features that are similar to those of the anchoring device  100  shown in  FIGS. 1-3B . The device  500  includes a tubular body  510  and a tubular inner sleeve  530 . 
     The inner sleeve  530  of the device  500  shown in  FIGS. 5A-5C  is made of a single piece of formed shape memory material such as NiTi. The inner sleeve  530  shown in  FIG. 5A  defines anchors  532  in the same way that the body  110  of the device  100  shown in  FIGS. 1-3B  defines the openings  120  and anchors  132 . However, in other implementations, the anchors and inner sleeve are formed separately and the anchors are coupled to the inner sleeve. In such implementations, the inner sleeve can be made of any material and the anchors are made of a shape memory material. 
     The body  510  has a longitudinal axis  512 , an outer surface  514 , and an inner surface  516  opposite and radially spaced apart from the outer surface  514 . The body  510  includes two axially extending sections  518  that define a series of openings  520 . Each of the openings  520  extend from the outer surface  514  to the inner surface  516  of the body  510  and has a first axial end  524  and a second axial end  526  opposite and spaced apart from the first axial end  524 . 
     When assembled, the inner sleeve  530  is disposed within the hollow tubular body  510 , as shown in  FIG. 5A . As seen in  FIG. 5B , the openings  520  defined by the body  510  are located such that, when the inner sleeve  530  is disposed within the tubular body  510 , each of the anchors  532  are aligned with an opening  520  such that each anchor  532  extends along each of the openings  520  from the first axial end  524  to the second axial end  526 . When the anchors  532  are moved from the retracted position shown in  FIG. 5B  to the extended position shown in  FIG. 5C , the anchors  532  extend radially outwardly through their respective opening  520 . 
     The extended position and retracted position of the anchors  532  are set in a similar way as described above for the anchoring device  100  shown in  FIGS. 1-3B  by heating and cooling the inner sleeve  530  rather than the entire device  500 . The inner sleeve  530  can be disposed within the body  510  before or after the shape setting process. The device  500  can also be coupled to one or more objects  550  in a similar way as described above for the anchoring device  100  shown in  FIGS. 1-3B . 
     Although the sleeve  530  of the device  500  shown in  FIGS. 5A-5C  is an inner sleeve  530 , in other implementations, the sleeve is a tubular outer sleeve and the body defining one or more openings can be disposed within the outer sleeve. The anchors of the outer sleeve in these implementations would be shape set similarly to the anchors of the device shown in  FIG. 4  such that the anchors extend radially inwardly when in the extended position. 
       FIGS. 6A and 6B  show another implementation of anchors  632  of an anchoring device  600 . Unlike the anchors  132  shown in  FIGS. 1-3B , the anchors  632  of the anchoring device  600  shown in  FIGS. 6A and 6B  include resilient members  638 . Similar reference numbers are used for the anchoring device  600  shown in  FIGS. 6A and 6B  for features that are similar to those of the anchoring device  100  shown in  FIGS. 1-3B . 
     Each of the anchors  632  of the device  600  shown in  FIGS. 6A and 6B  include a resilient member  638  and shape memory material portion  632 ′ comprising NiTi. The resilient member  638  is a strip of resilient material that is coupled to the body  610  and shape memory material portion  632 ′ of the anchor  632 . The resilient member  638  is biased toward the extended position and urgable toward the retracted position. 
     A sheet of NiTi at or below the martensite finishing temperature is formed into a tubular body  610  by wrapping the NiTi sheet around a cylindrical form  680 , and slits  622  are cut through the NiTi sheet to define at least one opening  620  and a shape memory material portion  632 ′ of an anchor  632 , similar to the device  100  shown in  FIGS. 1-3B . However, unlike the device  100  shown in  FIGS. 1-3B , each anchor  632  is then deformed into a retracted position in which the anchors  632  are not curved along the axial direction, and the device  600  is heated to the shape setting temperature to set the austenite, extended position of the shape memory material portion  632 ′ of the anchors  632  of the device  600 . 
     Because the resilient member  638  is urgable toward the retracted position of the anchor  632 , and the shape memory material portion  632 ′ of the anchor  632  is rigid and not curved along the axial direction in the austenite state, the resilient member  638  is urged toward the retracted position when the temperature of the device  600  is above the austenite finishing temperature, as shown in  FIG. 6A . Once the temperature of the device  600  is cooled below the martensite finishing temperature, the shape memory material portion  632 ′ of the anchors  632  become malleable and allow the resilient members  638  to move toward their biased extended position, as shown in  FIG. 6B . Thus, while the anchoring device  100  shown in  FIGS. 1-3B  moves from the retracted position to the extended position when the temperature of the anchors  132  increases above the austenite finishing temperature, the implementation of an anchoring device  600  shown in  FIGS. 6A and 6B  moves from the retracted position to the extended position when the temperature of the anchors  632  decreases below the martensite finishing temperature. 
     In some implementations, the anchors  632  shown in  FIGS. 6A and 6B  can be used in place of or in combination with the anchors of any of the implementations disclosed herein. Although the resilient member  638  shown in  FIGS. 6A and 6B  is a strip of resilient material coupled to the body  610  and shape memory material portion  632 ′ of the anchor  632 , in other implementations, the resilient member is a spring or any other device that is capable of biasedly moving the anchor toward the extended position when the shape memory material portion is in the martensite state. 
     The bodies  110 ,  410 ,  510 ,  610  shown in each of the above described anchoring devices  100 ,  400 ,  500 ,  600  includes a polyethylene terephthalate (“PET”) coating  102 ,  402 ,  502 ,  602 . PET is biocompatible and has a higher modulus of elasticity than NiTi. The PET coating is also designed to be porous to promote bone growth and bonding. Although the coating  102 ,  402 ,  502 ,  602  shown in these figures is PET, any material coating having any of these desirable features can be used. In some implementations, the outer surface of the body, the anchors, and/or the outer sleeve include a PET coating. In implementations in which the inner surface of the device is meant to abut an object during coupling, the coating can be applied to the inner surfaces of the body, anchors, and/or inner sleeve. In implementations in which the body and anchors are separately formed, the body may be made of, or partially made of, PET, and the anchors are made of a shape memory material. 
     Although portions of the devices  100 ,  400 ,  500 ,  600  disclosed herein comprise NiTi, in other implementations, one or more portions of the device comprise any shape memory material. In some implementations, one or more portions of the device comprise any shape memory metal. In some implementations, one or more portions of the device comprise any shape memory metal. In some implementations, one or more portions of the device comprise Ti—Ni—Pd, Ti—Ni—Pt, Ni—Ti—Hf, Ni—Ti—Zr, Cu—Al—Ni, Cu—Al—Nb, Co—Al, Co—Ni—Al, Ni—Al, Ni—Mn, Ni—Mn—Ga, Zr—Cu, Ti—Nb, U—Nb, Ti—Pd, Ti—Au, Ti—Pt—Ir, Ta—Ru, Nb—Ru, Ni—Ti—Hf—Zr, Ni—Ti—Er, and/or any shape memory alloy. In some implementations, one or more portions of the device comprise any NiTi-based, Cu-based, and/or Fe-based alloys. In some implementations, the shape memory metal portions include a medical grade metal. 
     Although both ends of each anchor of the devices shown in the figures are coupled to the first and second axial ends of an opening, in some implementations, only a coupled end of each anchor is coupled to either the first or second axial end of the opening and a free end of each anchor is not directly coupled to the body. In these implementations, the anchors do not curve in the extended position. Instead, the anchors are bent at their coupled end relative to the body such that the free end of the anchor is further from the longitudinal axis of the body in the extended position than in the retracted position. 
     A number of example implementations are provided herein. However, it is understood that various modifications can be made without departing from the spirit and scope of the disclosure herein. As used in the specification, and in the appended claims, the singular forms “a,” “an,” “the” include plural referents unless the context clearly dictates otherwise. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. Although the terms “comprising” and “including” have been used herein to describe various implementations, the terms “consisting essentially of” and “consisting of” can be used in place of “comprising” and “including” to provide for more specific implementations and are also disclosed. 
     Disclosed are materials, systems, devices, methods, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are products of the disclosed methods, systems, and devices. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutations of these components may not be explicitly disclosed, each is specifically contemplated and described herein. For example, if a device is disclosed and discussed each and every combination and permutation of the device, and the modifications that are possible are specifically contemplated unless specifically indicated to the contrary. Likewise, any subset or combination of these is also specifically contemplated and disclosed. This concept applies to all aspects of this disclosure including, but not limited to, steps in methods using the disclosed systems or devices. Thus, if there are a variety of additional steps that can be performed, it is understood that each of these additional steps can be performed with any specific method steps or combination of method steps of the disclosed methods, and that each such combination or subset of combinations is specifically contemplated and should be considered disclosed.