Patent Publication Number: US-11026729-B2

Title: Methods, devices, and systems for blood flow

Description:
CROSS REFERENCE 
     The present application is a divisional of U.S. application Ser. No. 15/838,781 entitled “Methods, Devices, And Systems for Blood Flow” filed Dec. 12, 2017, which is a divisional of U.S. application Ser. No. 15/148,464 entitled “Methods, Devices, And Systems For Blood Flow” filed May 6, 2016, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     The present disclosure relates generally to methods, systems, and devices for blood flow. 
     BACKGROUND 
     Soft tissues, such as ligaments, tendons, and muscles, are attached to a large portion of the human skeleton. In particular, many ligaments and tendons are attached to the bones which form joints, such as shoulder and knee joints. A variety of injuries and conditions require attachment or reattachment of a soft tissue to bone and/or surrounding tissue. For example, when otherwise healthy tissue has been torn away from a bone, surgery is often required to reattach the tissue to the bone to allow healing and a natural reattachment to occur. 
     One example of otherwise healthy tissue being torn away from a bone is a rotator cuff tear in which a shoulder rotator cuff tendon is partially or completely torn from a humerus. Surgery to reattach the rotator cuff tendon to the humerus has a failure rate as high as 40%. One way that has been developed to help reduce this failure rate is to add blood to the repair site to aid in and improve the healing process, as blood includes healing factors. One method to add blood is to decorticate or otherwise scuff the bone having the tendon attached thereto to induce some bleeding in the bone. Another method to add blood is to create microfracture holes in the bone having the tendon attached thereto to cause blood to “weep” from the microfracture holes. However, the blood clots within a short amount of time after the decortication, scuffing, or microfracture, typically within minutes or hours, so there is a limited amount of blood added to the repair site, which may limit the added blood&#39;s healing effects, and the blood is only added for a short time after the bone is decorticated, scuffed, or microfractured during the performance of the surgical procedure, which may not promote long term healing. 
     Accordingly, there remains a need for improved methods and devices for methods, systems, and devices for blood flow. 
     SUMMARY 
     In general, methods, systems, and devices for blood flow are provided. 
     In one aspect, a surgical device is provided that in one embodiment includes a biocompatible tubular member configured to be implanted in a bone of a patient. The tubular member has a solid sidewall defining an inner lumen extending through the tubular member such that blood can flow into the inner lumen through a first open end of the inner lumen and out of the inner lumen through a second open end of the inner lumen. The tubular member includes an anti-coagulation agent on the solid sidewall. 
     The surgical device can vary in any number of ways. For example, the inner lumen can be open and free of occlusions. For another example, the inner lumen can have a bioabsorbable material disposed therein that occludes the inner lumen such that the blood cannot flow out of the inner lumen through the second open end of the inner lumen until the bioabsorbable material has been at least partially absorbed by the patient&#39;s body. For yet another example, the tubular member can include a retaining member configured to engage the bone in which the tubular member is implanted to retain the tubular member within the bone. For still another example, the anti-coagulation agent can be coated on a surface of the solid sidewall. For another example, the anti-coagulation agent can be impregnated in a material forming the solid sidewall. For still another example, the anti-coagulation agent can include at least one of heparin, heparin sulfate, warfarin, hirudin, hirulog, coumarin, phosphorylcholine, indiandione, antithrombin III, bemiparin, dalteparin, danaparoid, enoxaparin, nadroparin, parnaparin, reviparin, sulodexide, tinzaparin, anticoagulant citrate dextrose solution A (ACD-A), ethylenediaminetetraacetic acid (EDTA), citrate, oxalate, a factor Xa inhibitor, and a thrombin inhibitor. For another example, the tubular member can be bioabsorbable. For yet another example, the tubular member can be non-bioabsorbable. For still another example, the tubular member can have a first retaining member configured to engage the bone in which the tubular member is implanted to resist distal advancement of the tubular member into the bone, and the tubular member can have a second retaining member spaced apart from the first retaining member and configured to engage the bone in which the tubular member is implanted to resist proximal advancement of the tubular member from the bone. 
     For another example, the inner lumen can have a plug removably disposed therein that occludes the inner lumen such that the blood cannot flow out of the inner lumen through the second open end of the inner lumen until the plug is removed from the inner lumen, and the plug can be configured to be implanted in the patient with the tubular member. In at least some embodiments, the plug can be made from an energy activated material disposed therein that occludes the inner lumen until the energy activated material is activated by application of energy thereto. In at least some embodiments, the plug can be a knitted material that occludes the inner lumen until the knitted material is pulled to cause the knitted material to unravel. In at least some embodiments, the plug can have a suture extending therefrom. The suture can be configured to extend from inside the patient&#39;s body to outside the patient&#39;s body and to be pulled from outside the patient&#39;s body and thereby remove the plug from the inner lumen of the tubular member. 
     In another embodiment, a surgical device includes a biocompatible anchor configured to be implanted in a bone of a patient. The anchor has at least one bone-engaging surface feature on an exterior surface thereof that is configured to engage the bone to secure the anchor in the bone. The anchor has an inner lumen extending therethrough such that blood can flow into the inner lumen through a first open end of the inner lumen and out of the inner lumen through a second open end of the inner lumen when the anchor is implanted in the bone. The anchor includes an anti-coagulation agent. 
     The surgical device can have any number of variations. For example, the anti-coagulation agent can be coated on a surface of the anchor. For another example, the anti-coagulation agent can be impregnated in a material forming the anchor. For yet another example, the anti-coagulation agent can include at least one of heparin, heparin sulfate, warfarin, hirudin, hirulog, coumarin, phosphorylcholine, indiandione, antithrombin III, bemiparin, dalteparin, danaparoid, enoxaparin, nadroparin, parnaparin, reviparin, sulodexide, tinzaparin, anticoagulant citrate dextrose solution A (ACD-A), ethylenediaminetetraacetic acid (EDTA), citrate, oxalate, a factor Xa inhibitor, and a thrombin inhibitor. For still another example, a suture coated with or impregnated with an anti-coagulation agent can be coupled to the anchor. For another example, the anchor can have a solid sidewall defining an inner lumen through which the blood flows. For yet another example, the anchor can have at least one hole formed through a sidewall thereof, and the at least one hole can be in communication with the inner lumen such that the blood can flow into the inner lumen through the hole. 
     In another aspect, a surgical method is provided that in one embodiment includes forming a hole in a bone of a patient in a soft tissue repair procedure, and implanting an implant in the hole. The implant includes an anti-coagulation agent. The implanted implant allows blood to flow therethrough. 
     The surgical method can vary in any number of ways. For example, the implant can be an anchor, and the anchor can have at least one bone-engaging surface feature on an exterior surface thereof that engages the bone to secure the anchor in the hole. For another example, the implant can be a tubular member, and the inner lumen can be open and free of occlusions when the implant is implanted in the hole such that the blood is allowed to begin flowing through the implanted implant before completion of the soft tissue repair procedure. For still another example, the method can include implanting an anchor in the bone at a site a distance away from a site where the implant is implanted, and the implant can be a tubular member that is not connected to the anchor with any implanted matter. For another example, the implant can have a solid sidewall defining an inner lumen through which the blood flows. For yet another example, the implant can have at least one hole formed through a sidewall thereof, and the at least one hole can be in communication with an inner lumen of the implant through which the blood flows such that the blood can flow into the inner lumen through the hole. 
     For yet another example, the implant can be a tubular member, and the inner lumen can be occluded when the implant is implanted in the hole such that the blood is prevented from flowing through the implanted implant until a selected amount of time has lapsed after completion of the soft tissue repair procedure. The method can also include removing a plug from within the inner lumen of the implanted tubular member and thereby allow blood to begin flowing through the implanted tubular member, or the implanted tubular member can have bioabsorbable material disposed in the inner lumen that occludes the inner lumen until the bioabsorbable material is at least partially absorbed by the patient&#39;s body after the selected amount of time has lapsed after completion of the soft tissue repair procedure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       This invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of one embodiment of an implant; 
         FIG. 2  is another perspective view of the implant of  FIG. 1  with directional flow arrows; 
         FIG. 3  is a perspective partially transparent view of one embodiment of the implant of  FIG. 1  implanted in a patient; 
         FIG. 4  is a side partially cross-sectional view of the implant of  FIG. 3  implanted in the patient; 
         FIG. 5  is a perspective view of one embodiment of an implant including a plug disposed therein; 
         FIG. 6  is a perspective view of the implant of  FIG. 5  with directional flow arrows and with the plug removed therefrom; 
         FIG. 7  is a perspective view of another embodiment of an implant including a plug disposed therein; 
         FIG. 8  is a perspective view of the implant of  FIG. 7  with directional flow arrows and with the plug removed therefrom; and 
         FIG. 9  is a perspective partially transparent, partially cross-sectional view of another embodiment of an implant implanted in a patient. 
     
    
    
     DETAILED DESCRIPTION 
     Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. 
     Further, in the present disclosure, like-named components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-named component is not necessarily fully elaborated upon. Additionally, to the extent that linear or circular dimensions are used in the description of the disclosed systems, devices, and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such systems, devices, and methods. A person skilled in the art will recognize that an equivalent to such linear and circular dimensions can easily be determined for any geometric shape. Sizes and shapes of the systems and devices, and the components thereof, can depend at least on the anatomy of the subject in which the systems and devices will be used, the size and shape of components with which the systems and devices will be used, and the methods and procedures in which the systems and devices will be used. 
     Various exemplary methods, systems, and devices for blood flow are provided. In general, an implant can be configured to be implanted in bone and to delay clotting of blood flowing from the bone. The implant can include an anti-coagulation agent to delay the clotting of the blood. The anti-coagulation agent can be a coating on the implant, can be natural to a material forming the implant, or can be impregnated into a material forming the implant. Although the anti-coagulant agent can be formed on a portion of the implant over which blood flows, the anti-coagulant agent can be present on an entire surface of the implant. In an exemplary embodiment, the implant is implanted in a bone in a surgical procedure for securing a soft tissue to bone, such as a rotator cuff repair procedure or an anterior cruciate ligament (ACL) repair procedure. The implant delaying the clotting of blood flowing from the bone may lengthen an amount of time the blood flows from the bone (as compared to the implant being implanted without the implant including the anti-coagulation agent and as compared to the implant not being implanted at all), which may aid in and improve the healing process by increasing an amount of blood that flows to the repair site and hence increasing a chance of the surgical procedure&#39;s success. The implant delaying the clotting of blood flowing from the bone may allow the blood to begin flow at a selected time after the surgical procedure has ended, which may aid in and improve the healing process by adding blood flow to the repair site at a time subsequent to when blood would have already clotted if the blood flow had begun during the surgical procedure (e.g., by decorticating, scuffing, or microfracturing the bone during the surgical procedure to induce blood flow). 
     The implants described herein can include any of a variety anti-coagulation or nonthrombogenic agents. Exemplary anti-coagulation agents include heparin, heparin sulfate, warfarin, hirudin, hirulog, coumarin, phosphorylcholine, indiandione, antithrombin III, bemiparin, dalteparin, danaparoid, enoxaparin, nadroparin, parnaparin, reviparin, sulodexide, tinzaparin, anticoagulant citrate dextrose solution A (ACD-A), ethylenediaminetetraacetic acid (EDTA), citrate, oxalate, factor Xa inhibitors, thrombin inhibitors, and other factor inhibitors or derivatives thereof. The implant&#39;s anti-coagulation agent can include a single anti-coagulation agent or a combination of multiple anti-coagulation agents. 
     The implants described herein can be made from any of a variety of materials. In some embodiments, the implant can be made from a non-bioabsorbable material (a single non-bioabsorbable material or a combination of multiple non-bioabsorbable materials) such that the implant is non-bioabsorbable. Exemplary non-bioabsorbable materials include polyetheretherketone (PEEK), polysulfone, polyester, silicone, and metals (e.g., stainless steel, titanium, etc.). In other embodiments, the implant can be made from a bioabsorbable material (a single bioabsorbable material or a combination of multiple bioabsorbable materials) such that the implant is bioabsorbable. A rate of a bioabsorbable implant&#39;s absorption can be tailored based on a size (length and/or diameter) of the implant and a type of bioabsorbable material forming the implant since different materials can absorb at different rates. Exemplary bioabsorbable materials include polylactic acid (PLA), polyglycolic acid (PGA), Biocryl® Rapide available from DePuy Mitek of Raynham, Mass., a resorbable metal (e.g., magnesium, zinc, iron, and alloys thereof), aliphatic polyesters, poly(amino acids), copoly(ether-esters), polyalkylene oxalates, polyamides, tyrosine derived polycarbonates, poly(iminocarbonates), polyorthoesters, polyoxaesters, polyamidoesters, polyoxaesters containing amine groups, poly(anhydrides), polyphosphazenes, polyurethanes, poly(ether urethanes), poly(ester urethanes), poly(propylene fumarate), poly(hydroxyalkanoate) and polydioxanone (PDS). Examples of aliphatic polyesters include homopolymers and copolymers of lactide (which includes lactic acid, D-, L- and meso lactide); glycolide (including glycolic acid); epsilon-caprolactone; p-dioxanone (1,4-dioxan-2-one); trimethylene carbonate (1,3-dioxan-2-one); alkyl derivatives of trimethylene carbonate; delta-valerolactone; beta-butyrolactone; gamma-butyrolactone; epsilon-decalactone; hydroxybutyrate; hydroxyvalerate; 1,4-dioxepan-2-one (including its dimer 1,5,8,12-tetraoxacyclotetradecane-7,14-dione); 1,5-dioxepan-2-one; 6,6-dimethyl-1,4-dioxan-2-one; 2,5-diketomorpholine; pivalolactone; alpha,alpha diethylpropiolactone; ethylene carbonate; ethylene oxalate; 3-methyl-1,4-dioxane-2,5-dione; 3,3-diethyl-1,4-dioxan-2,5-dione; 6,6-dimethyl-dioxepan-2-one; 6,8-dioxabicycloctane-7-one, and polymer blends thereof. Additional examples of polymer or polymer blends include a polydioxanone, a polyhydroxybutyrate-co-hydroxyvalerate, polyorthocarbonate, a polyaminocarbonate, and a polytrimethylene carbonate. The aliphatic polyesters can be homopolymers or copolymers (random, block, segmented, tapered blocks, graft, triblock, etc.) having a linear, branched or star structure. Whether bioabsorbable or non-bioabsorbable, the implants described herein are biocompatible to allow for their safe implantation in patients. 
     The implants described herein can include a biocompatible ceramic material. Exemplary biocompatible ceramic materials include hydroxyapatite, alpha-tricalcium phosphate, beta-tricalcium phosphate, bioactive glass, calcium phosphate, calcium sulfate, calcium carbonate, xenogeneic and allogeneic bone material, and combinations thereof. Exemplary bioactive glass materials include silicates containing calcium phosphate glass, and calcium phosphate glass with varying amounts of solid particles added to control resorption time. Exemplary compounds that can be incorporated into the calcium phosphate bioactive glass include, magnesium oxide, sodium oxide, potassium oxide, and combinations thereof. 
       FIG. 1  illustrates one embodiment of an implant  10  configured to be implanted in bone and to delay clotting of blood flowing from the bone. The implant  10  is a tubular member in the form of a tube and has an inner lumen  12  extending between proximal and distal ends  14 ,  16  thereof. The proximal and distal ends  14 ,  16  are thus open ends. The inner lumen  12  allows fluid (e.g., blood) to flow through the implant  10  when the implant  10  is implanted in a body of a patient (e.g., in a bone of a patient). Arrows  18  in  FIG. 2  illustrate a distal-to-proximal direction of possible fluid flow through the implant  10 . Fluid flow through the implant  10  in use is discussed further below. 
     The inner lumen  12  is open and free of occlusions. The inner lumen  12  may thus provide a continuous flow path through the implant  10  and may do so immediately upon implantation in a body of a patient, which may allow fluid to begin immediately flowing through the implant  10 . The inner lumen  12  is defined by an inner surface  20  of the implant  10  (e.g., an inner sidewall thereof). The inner lumen  12  has a cylindrical shape and a circular cross-sectional shape in this illustrated embodiment, which may facilitate fluid flow therethrough and/or help prevent the inner lumen  12  from clogging. However, other shapes (e.g., cone-shaped, etc.) and other cross-sectional shapes (e.g., oval cross-sectional shape, etc.) are possible. The inner surface  20  is solid. The solid nature of the inner surface  20  allows that, once fluid enters the inner lumen  12  through either the inner lumen&#39;s open proximal end or open distal end, the fluid cannot exit the implant  20  through the inner surface  20  (e.g., through pore(s) or window(s) formed in the inner surface  20 ). Instead, the fluid can only exit the inner lumen  12  through the open proximal end or open distal end. Similarly, the solid nature of the inner surface  20  provides that fluid can only enter the inner lumen  12  through the open proximal end or the open distal end. Fluid may thus predictably flow through the inner lumen  12  and thereby help ensure that the fluid flows to an intended site (e.g., that blood flows through the inner lumen  12  to an intended tissue repair site). The inner surface  20  is smooth and free of protrusions, indentations, and other obstructions thereon or therein, which may facilitate fluid flow through the inner lumen  12  and/or help prevent the inner lumen  12  from clogging. 
     In other embodiments, an inner surface of an implant that defines an inner lumen of the implant can have one or more openings formed therethrough. The one or more openings can each be in communication with the inner lumen. Fluid can thus flow into the inner lumen through the one or more openings. The implant can have an open distal end such that fluid can enter the inner lumen through an opening at the open distal end and through the one or more openings, or the implant can have a closed distal end such that fluid cannot enter the inner lumen through the implant&#39;s distal end but can enter the inner lumen through the one or more side openings of the implant. 
     Referring again to  FIG. 1 , the inner lumen  12  is straight and is aligned with a longitudinal axis A of the implant  10 . The inner lumen  12  can, however, be offset radially from the longitudinal axis A and/or be curved relative to the longitudinal axis A. 
     The implant  10  includes at least one retaining member configured to engage a bone in which the implant  10  is implanted to retain the implant  10  therein. The retaining member(s) can have a variety of sizes, shapes, and configurations. In this illustrated embodiment, the implant  10  includes a proximal retaining member  22  and a distal retaining member  24 . 
     The proximal retaining member  22  is configured to prevent the implant  10  from moving distally once the proximal retaining member  22  engages the matter in which the implant  10  is implanted (e.g., engages a proximal surface of a bone having a hole formed therein in which the implant  10  is disposed). In other words, the proximal retaining member  22  is configured to prevent the implant  10  from advancing too far distally in bone (or other matter in which the implant  10  is implanted), which may also help a surgeon or other user implanting the implant  10  know when the implant  10  has been fully distally advanced into the bone (or other matter). A distal surface of the proximal retaining member  22  is configured to engage the matter. The proximal retaining member  22  extends radially outward from the implant&#39;s proximal end  14 , thereby allowing the proximal end  14  of the implant  10  to have a diameter that is greater than a diameter of a body  26  of the implant  10 . The body  26  can thus be configured to be disposed in matter in which the implant  10  is implanted while the proximal retaining member  22  remains outside of the matter. The proximal retaining member  22  is in the form of a flange extending radially outward from the proximal end  14  of the implant  10 . The flange has a circular ring shape and extends around an entire perimeter of the implant&#39;s proximal end  14 . The flange can, however, have other shapes (e.g., oval, triangular, etc.) and can be discontinuous around the perimeter of the implant&#39;s proximal end  14  (e.g., a series of independent flange members extending radially outward from the implant&#39;s proximal end  14 , a single tab extending radially outward from the implant&#39;s proximal end  14 , etc.). The proximal retaining member  22  extending around the entire perimeter of the implant&#39;s proximal end  14  may help ensure that the proximal retaining member  22  engages a surface of the matter (e.g., bone) in which the implant  10  is implanted. 
     The distal retaining member  24  is configured to prevent the implant  10  from moving proximally once the distal retaining member  24  engages the matter in which the implant  10  is implanted (e.g., engages a distal surface of a bone having a hole formed therein in which the implant  10  is disposed). Depending on use of the implant  10 , the distal retaining member  24  can also be configured to prevent the implant  10  from moving distally once the distal retaining member  24  engages the matter in which the implant  10  is implanted. In other words, if the distal retaining member  24  is contained within the matter in which the implant  10  is implanted, as opposed to being located outside of the matter like the proximal retaining member  22 , the distal retaining member  24  can be configured to prevent both proximal and distal movement of the implant  10  within the matter. The distal retaining member  24  is in the form of a protrusion extending radially outward from the body  26  of the implant  10  near the implant&#39;s distal end  16 . The protrusion has a circular ring shape and extends around an entire perimeter of the implant&#39;s body  26 . The protrusion can, however, have another shape (e.g., oval, triangular, etc.) and can be discontinuous around the perimeter of the implant&#39;s body  26  (e.g., a series of independent protrusions extending radially outward from the implant&#39;s body  26 , a single protrusion extending radially outward from the implant&#39;s body  26 , etc.). 
     The proximal and distal retaining members  22 ,  24  are configured to cooperate to retain the implant  10  within the matter in which the implant  10  is implanted. In other words, the proximal retaining member  22  is configured to prevent distal movement of the implant  10  within the matter and the distal retaining member  24  is configured to prevent proximal movement  10  of the implant  10  within the matter (and, in at least some embodiments, to also prevent distal movement  10  of the implant  10  within the matter). In an exemplary embodiment, a distance D between the proximal and distal retaining members  22 ,  24  corresponds to a depth of cortical bone of a bone in which the implant  10  may be implanted. In this way, the implant  10  can be configured to “trap” the cortical bone between the proximal and distal retaining members  22 ,  24 , thereby allowing the implant  10  to grip the harder cortical bone rather than the softer cancellous bone that underlies the cortical bone. In an exemplary embodiment, the distance D is in a range of about 0.05 to 100 mm. 
     The implant  10  includes both of the proximal and retaining members  22 ,  24  in this illustrated embodiment, but an implant can include only one of the proximal and retaining members  22 ,  24 . Alternatively, an implant can include both of the proximal and retaining members  22 ,  24  and one or more additional retaining members along a length of the implant&#39;s body that are similar to the distal retaining member such that the body has a plurality of protrusions at different axial positions therealong, or an implant can lack the proximal retaining member  22  and can include the distal retaining member  24  and one or more additional retaining members along a length of the implant&#39;s body that are similar to the distal retaining member such that the body has a plurality of protrusions at different axial positions therealong. An implant having the distal retaining member  24  and one or more additional retaining members similar thereto like may help ensure that at least one retaining member securely engages the matter in which the implant is implanted. 
     The distal end  16  of the implant  10  can be configured to facilitate insertion of the implant  10  into matter in a distal direction, which would be the typical approach direction for the implant&#39;s implantation. The distal end  16  of the implant  10  is angled to facilitate insertion of the implant  10  into matter, e.g., into bone in which the implant  10  will be implanted. The angled distal end can be sharp to further to facilitate insertion of the implant  10  into the matter. In other embodiments, a distal end of an implant can be non-angled, similar to the proximal end  14  of the implant  10 . 
     The implant  10  includes an anti-coagulation agent configured to prevent or delay coagulation of blood, e.g., to prevent or delay clotting. A length of time that the anti-coagulation agent prevents the blood from coagulating is generally a function of a type of the anti-coagulation agent and an amount of the anti-coagulation agent that is present, as will be appreciated by a person skilled in the art. In an exemplary embodiment, the length of time blood encountering the anti-coagulant agent flows before coagulating is in a range of about one to three hundred minutes, e.g., in a range of about four to twenty minutes, in a range of about four to fifteen minutes, in a range of about fifteen to twenty minutes, etc. 
     The anti-coagulation agent is coated on the implant  10  in the illustrated embodiment. The anti-coagulation agent is coated on an entirety of the implant&#39;s exposed surface, including on the inner surface  20  and on the implant&#39;s outer surface  28 , which may help ensure that any blood that comes into contact with the implant  10  is encouraged to flow and not clot. Similarly, each of an implant including an anti-coagulation agent as natural to a material forming the implant and an implant including an anti-coagulation agent impregnated into a material forming the implant encourages any blood that comes into contact with the implant to flow and not clot. In other embodiments, an implant can have an anti-coagulation agent coated on only a partial portion thereof. For example, the anti-coagulation agent can be coated only on an inner surface of an implant (e.g., the inner surface  20  of the implant  10 ), which may help encourage blood flowing through the implant&#39;s inner lumen toward a tissue repair site to not clot after exiting the implant. Similarly, an implant including an anti-coagulation agent as natural to a material forming the implant can include that material in only a portion of the implant (such as only in the implant&#39;s body or only along an inner surface defining an implant&#39;s inner lumen), and an implant including an anti-coagulation agent impregnated into a material forming the implant can include that material in only a portion of the implant (such as only in the implant&#39;s body or only along an inner surface defining an implant&#39;s inner lumen). The coating of the anti-coagulation agent, whether coated on an entirety of the implant&#39;s exposed surface or on only a partial portion of the implant&#39;s exposed surface, is, in at least some embodiments, a gradient coating. 
     In use, the implant  10  and other implants disclosed herein can be used in any number of a variety of surgical procedures and can be driven into a bone in the surgical procedure. For example, the surgical procedure can include a soft tissue repair procedure for securing a soft tissue to bone, such as a rotator cuff repair, Achilles, or ACL repair procedure. 
     In general, a surgical procedure can be performed as it would be typically performed on a patient except that an implant is implanted in a bone adjacent a target site in which blood flow is desired to facilitate healing, such as in a bone adjacent to a soft tissue reattachment site. A single implant can be implanted in the patient, or a plurality of implants can be implanted in the patient. If a plurality of implants are implanted, each of the implants can be identical to one another or any one or more of the implants can differ from any one or more of the other implants, e.g., have different sizes, include different anti-coagulation agents, etc. 
       FIGS. 3 and 4  illustrate one embodiment of use of the implant  10 . Other implants disclosed herein can be similarly used.  FIGS. 3 and 4  illustrate the implant  10  implanted in a humerus  30  of a patient  32  in rotator cuff repair. Only one of the implants  10  is implanted in the bone  30 , but as mentioned above, more than one implant can be implanted. When a plurality of implants are implanted, at least one of the implants can have an unoccluded inner lumen, like the implant  10 , to allow for blood flow therethrough at a time of surgery, and at least one of the implants can have an occluded lumen (for example, the implants of  FIGS. 5-8  discussed below) to allow for blood flow therethrough at a time after the surgery. More blood may thus be allowed to flow at the soft tissue reattachment site  34  throughout the healing process. Alternatively, when a plurality of implants are implanted, all of the implants can have an occluded lumen and be configured to have its lumen unoccluded at different times post-surgery, e.g., by plugs in the various inner lumens being removed at different times manually or naturally via absorption. 
     As mentioned above, the rotator cuff procedure can be performed as it would be typically performed on a patient except that the implant  10  is implanted in a bone (the humerus  30 ) adjacent to the soft tissue reattachment site  34 , which here is where a rotator cuff tendon  36  is secured to the humerus  30  using sutures  38  and anchors (obscured in the bone  30  under the tendon  36 ). The implant  10  is implanted lateral to the tendon  36 , but instead the implant  30  can be implanted under the tendon  36 . 
     In an exemplary embodiment, the implant  10  is implanted after the rotator cuff tendon  36  is secured to the humerus  30 , which may allow the rotator cuff tendon  36  to be secured to the humerus  30  without the implant  10  interfering with the securing process. 
       FIG. 4  illustrates the distance D between the proximal and distal retaining members  22 ,  24  as corresponding to a depth of cortical bone  40  of the humerus  30  with the proximal retaining member  22  engaging a proximal surface of the cortical bone  40  (and hence a proximal surface of the humerus  30 ) and the distal retaining member  24  engaging a distal surface of the cortical bone  40 .  FIG. 4  also illustrates blood  42  flowing in a proximal direction, as indicated by arrow  44 , through the inner lumen  12  with the blood  42  entering the implant  10  through the implant&#39;s open distal end and exiting the implant  10  through the implant&#39;s open proximal end.  FIG. 3  also shows the exiting of the blood  42  from the implant  10 . The blood  42  may thus flow in a direction toward the tissue reattachment site  34  and encourage healing thereat. 
     The implant  10  can be implanted in the humerus  30  in any of a variety of ways, as will be appreciated by a person skilled in the art. For example, the implant  10  can be advanced into the patient in a minimally invasive fashion through the patient&#39;s skin  44  and driven into the humerus  30  similar to the driving of the anchors into the humerus  30 , e.g., by using a driver tool to push the implant  10  into the humerus  30 . 
       FIGS. 5 and 6  illustrate another embodiment of an implant  46  configured to be implanted in bone and to delay clotting of blood flowing from the bone. The implant  46  is a tubular member in the form of a tube. The implant  46  is generally configured and used similar to the implant  10  of  FIG. 1 , e.g., includes an inner lumen  48  defined by a solid inner surface  50  of the implant  46  and aligned with a longitudinal axis A 2  of the implant  46 , a proximal retaining member  52  in the form of a flange, a distal retaining member  54  in the form of a ring-shaped protrusion, an angled distal end  56 , and an anti-coagulation agent in the form of a coating that coats an entirety of the implant&#39;s exposed surface. 
     The inner lumen  48  of the implant  46  of  FIGS. 5 and 6  is occluded in a first configuration of the implant  46 , shown in  FIG. 5 . Fluid cannot flow through open proximal and distal ends of the implant  46  in the first configuration due to the occlusion. Fluid can enter the inner lumen  48  through the implant&#39;s open distal end, but the occlusion prevents the fluid&#39;s exit from the implant  48  through the proximal open end. In other embodiments, fluid can be prevented from entering an implant&#39;s inner lumen at all due to an occlusion in the implant&#39;s inner lumen. The implant  48  is configured to move from the first configuration to a second configuration, shown in  FIG. 6 , in which the inner lumen  48  is not occluded. The implant  46  in the second configuration is thus like the implant  10  of  FIG. 1  with its inner lumen  48  being open and free of occlusions. Arrows  58  in  FIG. 6  shows a distal-to-proximal direction of possible fluid flow through the implant  46  in the second configuration. In another embodiment, the implant in the second configuration can be partially open and partially occluded so as to allow fluid flow therethrough while a portion of the plug remains in the implant&#39;s inner lumen. 
     The implant  46  is configured to be implanted in a patient in the first configuration and to be moved from the first configuration to the second configuration after the implantation. The implant  46  is configured to move from the first configuration to the second configuration at a selected time after the implantation of the implant  46  in a patient. Fluid can thus begin to flow through the implant  46  at a selected time, which may allow blood flow at an intended surgical site to begin at a time selected by a doctor or other medical professional as desired based on any one or more factors, such as the patient&#39;s medical history, the doctor&#39;s/professional&#39;s personal preference, etc. In at least some embodiments, the selected time is after completion of the surgical procedure in which the implant  46  is implanted in a patient. The blood flow may thus begin post-surgery, which may help accelerate and/or otherwise improve healing post-surgery. The selected time can vary. For example, the selected time can be a time in a range of one day to several days, in a range of one day to one week, one week, or in a range of two weeks to four weeks (e.g., two weeks after surgery, twenty days after surgery, four weeks after surgery, etc.). In other embodiments, the selected time is at or near an end of the surgical procedure in which the implant  46  is implanted in a patient, e.g., as a last step of the procedure before access to the patient is closed (e.g., an access portal incision into the patient is closed, etc.). The blood flow may thus begin as late as possible in the surgery. 
     As shown in  FIG. 5 , the inner lumen  48  of the implant  46  is occluded by a plug  60  that is at least partially disposed in the inner lumen  48 . The plug  60  is fully contained within the inner lumen  48  in this illustrated embodiment. The plug  60  being fully contained within the inner lumen  48  may help minimize a profile of the implant  48  and thereby help prevent the implant  48  from poking into, rubbing against, or otherwise disturbing tissue structures near the implant  48  when implanted in a patient. In other embodiments, a plug of an implant can be partially outside of the implant when the implant is in its first configuration, e.g., a proximal portion of the plug can extend proximally beyond a proximal end of the implant. The plug being partially contained within the inner lumen may make the plug easier to remove from the implant. 
     The plug  60  can have a variety of sizes, shapes, and configurations. In general, the plug  60  has a size and shape that allows the plug  60  to occlude the inner lumen  48  so fluid cannot flow through the inner lumen  48  when the plug  60  is disposed therein. The inner lumen  48  in this illustrated embodiment has a cylindrical shape and a circular cross-sectional shape, so the plug  60  has a corresponding cylindrical shape and circular cross-sectional shape. The plug  60  has a length that is less than a length of the inner lumen  48 , as shown in  FIG. 6 , which may make the plug  60  easier to remove from the inner lumen  48 . 
     The plug  60  is configured to be removed from the inner lumen  48  at the selected time to move the implant  46  from the first configuration to the second configuration. The plug  60  is attached to a suture  62  that extends proximally therefrom, and hence extends proximally from the implant  46 . The suture  62  is configured to be manipulated by a user (e.g., a surgeon, a nurse, etc.), e.g., pulled in a proximal direction, to remove the plug  60  from the inner lumen  48 . The suture  62  has a length that is long enough to allow the suture  62  to extend from the plug  60  implanted in a body of a patient and through a skin of the patient such that a proximal portion of the suture  62  is located outside of the patient. The suture  62  can thereby be manipulated from outside the patient&#39;s body to remove the plug  60  from the inner lumen  48 , e.g., by pulling on the proximal portion of the suture  62 , and allow blood to flow through the implant  46 . The suture  62  can be trimmed in length outside of the patient&#39;s body such that only a short length of suture is located outside the patient&#39;s body, which may help prevent the suture  62  from being accidentally pulled before the selected time, even if the proximal portion of the suture  62  is covered on the patient&#39;s skin, such as with a bandage. 
     The suture  62  can be attached to the plug  60  in any of a variety of ways, e.g., being molded therein, by being glued thereto with adhesive, by being heat-melted thereto, by being tied thereto, etc. The suture  62  includes a single strand, but in other embodiments a suture attached to a plug can include multiple strands. The plug  60  is attached to only one suture  62 , but in other embodiments, a plug can be attached to multiple sutures that each extend proximally from the plug and is configured to be manipulated to remove the plug from the implant. 
     In an exemplary embodiment, the plug  60  is made from a non-bioabsorbable material (a single material or a combination of multiple materials) such that the plug  60  is non-bioabsorbable, and the suture  62  is made from a non-bioabsorbable material (a single material or a combination of multiple materials) such that the suture  62  is non-bioabsorbable. The inner lumen  48  may thus become unoccluded at a selected time, e.g., the implant  46  can be moved from the first configuration to the second configuration at a selected time, thereby allowing the time to be selected by a doctor or other medical professional as desired for the particular patient in which the implant  46  is implanted based on any one or more factors, such as the patient&#39;s medical history, the doctor&#39;s/professional&#39;s personal preference, etc. In other embodiments, the plug  60  and/or the suture  62  can be made from a bioabsorbable material (a single material or a combination of multiple materials) so as to be bioabsorbable. The plug  60  and suture  62  being bioabsorbable allows the plug  60  and suture  62  to be removed from the inner lumen  48  at a selected time before a known absorption time of the plug  60  and suture  62  or to be left in the inner lumen  48  to dissolve within the patient&#39;s body at the known absorption time. 
     In another embodiment, an implant similar to the implant  46  of  FIG. 5  has a plug partially disposed in an inner lumen of the implant and extending proximally beyond the implant&#39;s proximal end. The plug has a length that is long enough to allow the plug to extend from the plug implanted in a body of a patient and through a skin of the patient such that a proximal portion of the plug is located outside of the patient. The plug is configured to configured to be manipulated by a user (e.g., a surgeon, a nurse, etc.), e.g., pulled in a proximal direction, to remove the plug from the inner lumen of the implant. Thus, instead of having a suture attached thereto like the plug  60  and the suture  62  of  FIGS. 5 and 6 , the plug itself is configured to extend from the patient&#39;s body to allow removal of the plug from the implant&#39;s inner lumen to begin blood flow therethrough. In an exemplary embodiment, the plug is made from a knitted material configured to narrow in diameter when pulled so as to allow the plug to occlude the implant&#39;s inner lumen (e.g., in a first configuration of the implant) and then, when pulled, unravel to narrow in diameter and not occlude the implant&#39;s inner lumen (e.g., in a second configuration of the implant) and be removed from the inner lumen. The plug can thus be configured to be pulled out of the patient&#39;s body through the patient&#39;s skin with the plug in its unraveled state. 
       FIGS. 7 and 8  illustrate another embodiment of an implant  64  configured to be implanted in bone and to delay clotting of blood flowing from the bone. The implant  64  is a tubular member in the form of a tube. The implant  64  is generally configured and used similar to the implant  10  of  FIG. 1 , e.g., includes an inner lumen  66  defined by a solid inner surface (obscured in  FIGS. 7 and 8 ) of the implant  64  and aligned with a longitudinal axis A 3  of the implant  64 , a proximal retaining member  68  in the form of a flange, a distal retaining member  70  in the form of a ring-shaped protrusion, an angled distal end  72 , and an anti-coagulation agent in the form of a coating that coats an entirety of the implant&#39;s exposed surface. 
     The implant  64  is configured to be implanted in a patient in a first configuration in which the inner lumen  66  is occluded such that fluid cannot flow therethrough and to be moved after the implantation from the first configuration to a second configuration in which the inner lumen  66  is at least partially unoccluded such that fluid can flow therethrough. The first configuration of the implant  64  is similar to the first configuration of the implant  46  of  FIG. 5  in that fluid cannot flow through open proximal and distal ends of the implant  64  in the first configuration due to the occlusion. The second configuration is a transitional state in which the occlusion gradually dissipates such that the inner lumen  66  becomes more unobstructed over time such that more fluid can flow through the inner lumen  66  over time. Eventually, the inner lumen  66  becomes fully unoccluded in the second configuration similar to the second configuration of the implant  46  of  FIG. 6 . 
     As shown in  FIG. 7 , the inner lumen  66  of the implant  64  is occluded by a plug  74  that is at least partially disposed in the inner lumen  66 . The plug  74  is fully contained within the inner lumen  66  in this illustrated embodiment, but similar to that discussed above regarding the plug  60  of  FIGS. 5 and 6 , in other embodiments, a plug can be partially outside of an implant. The plug  74  is made from a bioabsorbable material (a single material or a combination of multiple materials) so as to be bioabsorbable. The plug  74  is thus configured to dissolve within a patient&#39;s body so as to gradually dissipate from within the inner lumen  66  at a known absorption time accordingly to a known absorption rate of the material(s) forming the plug  74 .  FIG. 8  shows a plurality of areas (six) in the plug  74  in which material forming the plug  74  has dissolved to allow fluid flow, as shown by directional arrows  76 . The plug  74  being bioabsorbable allows the plug  74  to fully dissolve within the patient&#39;s body, as opposed to remaining the patient&#39;s body until such time it is manually removed therefrom, which may subject the patient to various risks such as injury from a loose plug within their body. The plug  74  being bioabsorbable allows the inner lumen  66  to become unoccluded at a predictable time post-surgery since an absorption rate of the material(s) forming the plug  74  will be known. A rate of the plug&#39;s absorption can be tailored based on a size of the plug  74 , a size (length and/or diameter) of the inner lumen  66  in which the plug  74  is at least partially disposed, and a type of bioabsorbable material forming the plug  74  since different materials can absorb at different rates. 
     In another embodiment, an implant similar to the implant  64  of  FIG. 7  has a plug that is at partially disposed in an inner lumen of the implant, but the plug is formed of a material configured to be activated by energy to move the implant from a first configuration in which the inner lumen is occluded to a second configuration in which the inner lumen is unoccluded. The material can be activated by the energy at a selected time after the implantation of the implant in a patient as selected by a doctor or other medical professional as desired based on any one or more factors, such as the patient&#39;s medical history, the doctor&#39;s/professional&#39;s personal preference, etc. 
     In an exemplary embodiment, the energy-activatable material forming the plug includes a material (a single material or a combination of multiple materials) configured to be activated by ultrasonic energy, such as high-energy focused ultrasound (HIFU) or a magnetic field for a magnetic material, such as pulsed electromagnetic field therapy (PEMF). In general, HIFU is a technique that locally heats an area within a patient&#39;s body, as will be appreciated by a person skilled in the art. This heating can cause the plug to dissolve and thereby unocclude the implant&#39;s inner lumen. Heating or ablation volumes using HIFU are traditionally on the order of 1 mm in diameter, which would be compatible with the implant. Examples of material configured to be activated by ultrasonic energy include a biomaterial configured to be shrunk by heating (such as a collagen-based structure), a polymer (such as polycaprolactone, which has a melting point of about 60 degrees Celsius), a foamed polymer configured to decrease in volume when heated, and a shape memory material (polymer or metal). The shape memory material can be configured to act as a valve within the implant&#39;s inner lumen by changing shape when activated by the energy. 
     An amount of energy required to dissolve the plug can vary, such as in a range of about 1 to 2 Joules. If the plug includes a thin membrane extending across the inner lumen, includes liquid to be heated to expand enough to break a seal, or to cause a shape memory material valve to open, the energy can be less than 1 Joule, and in at least some cases, substantially less than 1 Joule. 
     In at least some embodiments, the energy-activatable material forming the plug includes one or more cavities therein that each have contained therein an anti-coagulating agent. The implant can thus include an anti-coagulating agent in the one or more cavities and, optionally, as any one or more of a coating on at least a portion of the implant, natural to a material forming at least a portion of the implant, and impregnated into a material forming at least a portion of the implant. The anti-coagulating agent can be configured to be released from the one or more cavities when the energy-activatable material is activated. 
     In at least some embodiments, the plug formed of the energy-activatable material is in the form of a proximal cap sealing a proximal end of the inner lumen and a distal cap sealing a distal end of the inner lumen. An anti-coagulating agent is contained within the inner lumen between the proximal and distal caps. The implant can thus include an anti-coagulating agent in the inner lumen and, optionally, as any one or more of a coating on at least a portion of the implant, natural to a material forming at least a portion of the implant, and impregnated into a material forming at least a portion of the implant. The anti-coagulating agent can be configured to be released from the inner lumen when the energy-activatable material is activated to disrupt the proximal and distal caps either by pressure build-up in the inner lumen and/or the energy causing the proximal and distal caps to break. 
       FIG. 9  illustrates another embodiment of an implant  78  configured to be implanted in bone and to delay clotting of blood flowing from the bone. The implant  78  is in the form of an anchor configured to be implanted in bone and having an inner lumen extending therethrough (e.g., the anchor is cannulated). Surgical procedures such as soft tissue repair procedures traditionally use one or more anchors as part of the procedure. For example, the rotator cuff repair of  FIGS. 3 and 4  uses anchors, as mentioned above. Any or all of the one or more anchors used in the surgical procedures such as soft tissue repair procedures can be the implant  78  (or other implant in the form of an anchor described herein). The surgical procedure thus need not be performed any differently than traditionally performed except that the anchor(s) include an anti-coagulating agent to delay clotting of blood flowing from the bone and, optionally, bone need not be decorticated, scuffed, or microfractured to induce blood flow. The benefits of delayed blood clotting may thus be achieved without any disruption to a surgeon&#39;s preferred surgical procedure technique. The anti-coagulation agent is coated on the implant  78  in the illustrated embodiment. The coating is present on an entire surface of the implant  78 , but as mentioned above, the coating can be on only a portion of the implant  78 , e.g., a portion in which flowing blood is expected to flow on. However, as mentioned above, the implant  78  can instead or additionally have an anti-coagulation agent coated thereon (either on an entirety of the implant&#39;s exposed surface or on only a portion thereof), as natural to a material forming the anchor, and/or impregnated into a material forming the anchor. 
     As shown in  FIG. 9 , the implant  78  has an opening formed through a sidewall thereof. The opening is in communication with an inner lumen of the implant  78  through which fluid (e.g., blood) can flow. Fluid can thus flow into the inner lumen through the opening. The opening is located in an intermediate location of the implant  78  between proximal and distal end thereof. The proximal end of the implant  78  is open, and the distal end of the implant  78  is closed such that fluid entering the inner lumen through the opening can flow proximally and out of the open proximal end of the implant  78 . The opening in this illustrated embodiment includes two openings on opposite sides of the implant  78  (one of the openings is obscured in  FIG. 9 ), but an implant can include a single opening or more than two openings. 
       FIG. 9  illustrates the implant  78  implanted in a humerus  80  of a patient  82  in rotator cuff repair, but as mentioned above, the implant  78  can be used in other types of surgical procedures. Only one of the implants  78  is implanted in the bone  80 , but as mentioned above, more than one implant can be implanted. 
     As shown in  FIG. 9 , the anchor  78  is secured to the rotator cuff tendon  84  with a suture  86 . The suture  86  can include an anti-coagulation agent coated thereon (either on an entirety of the suture&#39;s exposed surface or on only a portion thereof), as natural to a material forming the suture  86 , and/or impregnated into a material forming the suture  86 . Thus, both the anchor  78  and the suture  86  can be configured to contribute to delayed blood clotting. Sutures used to secure other anchors used in the surgical procedure can similarly include an anti-coagulation agent coated thereon, as natural to a material forming the suture, and/or impregnated into a material forming the suture. 
     In this illustrated embodiment, the suture  86  is configured to slide through the inner lumen of the anchor  78 . The inner lumen is thus unoccluded, similar to the inner lumen  12  of the implant  10  of  FIG. 1 , to facilitate the suture&#39;s sliding therein. In embodiments of anchors that are used with a suture that does not slide within an inner lumen of the anchor (e.g., the anchor is used with a non-sliding suture), the inner lumen of the anchor can have a plug at least partially disposed therein similar to the bioabsorbable plug  74  of  FIG. 7 , and the anchor and/or the plug can include an anti-coagulating agent, as discussed above. 
     The anchor  78  is one embodiment of an anchor that includes an anti-coagulation agent. Other exemplary embodiments of anchors that can include an anti-coagulation agent coated thereon (either on an entirety of the implant&#39;s exposed surface or on only a portion thereof), as natural to a material forming the anchor, and/or impregnated into a material forming the anchor include the Healix Advance™ anchor available from DePuy Mitek of Raynham, Mass., Healix TI™, Healix PEEK™, and Healix BR™ Dual-Threaded anchors available from DePuy Mitek of Raynham, Mass., Healix Transtend™ anchor available from DePuy Mitek of Raynham, Mass., Versalok™ anchor available from DePuy Mitek of Raynham, Mass., the anchors described in U.S. Pat. No. 8,114,128 entitled “Cannulated Suture Anchor” filed Nov. 1, 2006, the content of which is hereby incorporated by reference in its entirety, and the anchors described in U.S. Pat. No. 8,702,754 entitled “Methods For Anchoring Suture To Bone” filed Sep. 14, 2007, the content of which is hereby incorporated by reference in its entirety. 
     A person skilled in the art will appreciate that the methods, systems, and devices disclosed herein have application in conventional minimally-invasive and open surgical instrumentation as well application in robotic-assisted surgery. 
     One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.