Patent Publication Number: US-11376115-B2

Title: Prosthetic ligament system for knee joint

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 12/788,978 filed on May 27, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 12/489,168 filed on Jun. 22, 2009, now U.S. Pat. No. 8,361,113 issued on Jan. 29, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 12/474,802 filed on May 29, 2009, now U.S. Pat. No. 8,088,130 issued on Jan. 3, 2012, which is a continuation-in-part of: (a) U.S. patent application Ser. No. 12/196,405 filed on Aug. 22, 2008, U.S. Pat. No. 8,128,658 issued on Mar. 6, 2012; (b) U.S. patent application Ser. No. 12/196,407 filed on Aug. 22, 2008, now U.S. Pat. No. 8,137,382 issued on Mar. 20, 2012; (c) U.S. patent application Ser. No. 12/196,410 filed on Aug. 22, 2008, now U.S. Pat. No. 8,118,836 issued on Feb. 21, 2012; and (d) a continuation-in-part of U.S. patent application Ser. No. 11/541,506 filed on Sep. 29, 2006, now U.S. Pat. No. 7,601,165 issued on Oct. 13, 2009. 
     This application is a divisional of U.S. patent application Ser. No. 12/788,978 filed on May 27, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 12/570,854 filed on Sep. 30, 2009, now U.S. Pat. No. 8,303,604 issued on Nov. 6, 2012, which is a continuation-in-part of: (a) U.S. patent application Ser. No. 12/014,399 filed on Jan. 15, 2008, now U.S. Pat. No. 7,909,851 issued on Mar. 22, 2011; and (b) U.S. patent application Ser. No. 12/014,340 filed on Jan. 15, 2008, now U.S. Pat. No. 7,905,904 issued on Mar. 15, 2011. 
     This application is a divisional of U.S. patent application Ser. No. 12/788,978 filed on May 27, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 12/702,067 filed on Feb. 8, 2010, now U.S. Pat. No. 8,672,968 issued on Mar. 18, 2014, which is a continuation of U.S. patent application Ser. No. 11/541,505 filed on Sep. 29, 2006, now U.S. Pat. No. 7,658,751 issued on Feb. 9, 2010. 
     This application is a divisional of U.S. patent application Ser. No. 12/788,978 filed on May 27, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 12/196,398 filed Aug. 22, 2008, now U.S. Pat. No. 7,959,650 issued on Jun. 14, 2011; which is a continuation-in-part of U.S. patent application Ser. No. 11/784,821 filed Apr. 10, 2007. 
     The disclosures of all the above applications are incorporated by reference herein. 
    
    
     FIELD 
     The following relates to a knee joint and, more particularly, relates to a prosthetic ligament system for a knee joint. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Articulating anatomical skeletal joints, such as knee joints include a plurality of ligaments, such as an anterior cruciate ligament (ACL). The ligaments extend between and connect the bones of the knee joint. In some cases, trauma or wear of the knee joint can necessitate replacement and/or repair of the ligament(s). 
     Conventional prosthetic ligaments for the knee, for example, can be made out of a graft of biological material (e.g., an autograft, allograft, xenograft, or artificial graft). These grafts are typically attached to the bones with a fastener (e.g., a bone screw, etc.) that is fixed to bone. 
     The following disclosure relates to a prosthetic ligament system that supports and restores normal movement of a knee joint. The prosthetic ligament system of the present disclosure can be quickly and conveniently implanted. 
     SUMMARY 
     A system for an anatomical joint with a first bone portion and a second bone portion is disclosed. The system includes a first fastener, a second fastener, and a prosthetic ligament member. The first fastener is operable to be connected to the first bone portion. The second fastener is operable to be connected to the second bone portion. The prosthetic ligament member is flexible and is directly coupled to both the first and second fasteners to support the first bone portion and the second bone portion for relative movement. According to one aspect, a portion of the prosthetic ligament member extends from the first fastener to the second fastener and has an adjustable length. According to another aspect, the system includes a biasing member associated with at least one of the first and second fasteners. The biasing member is operable to bias the prosthetic ligament member to thereby maintain tension in the prosthetic ligament member. 
     In various examples, the prosthetic ligament member extends from a first end to a second end, and includes an outer wall that defines a hollow longitudinal passage portion having a first end and a second end. In one example, the prosthetic ligament member is integrated one-piece device. The first end of the prosthetic ligament member extends into the first end of the longitudinal passage portion through the outer wall and out of the second end of the longitudinal passage portion through the outer wall to define a first adjustable length. The second end of the prosthetic ligament member extends into the second end of the longitudinal passage portion through the outer wall and out of the first end of the longitudinal passage portion through the outer wall to define a second adjustable length. 
     In another example, the prosthetic ligament member includes at least one first aperture and at least one second aperture that extend through the outer wall and are disposed between the first and second ends of the prosthetic ligament member. The at least one first and second apertures are disposed at opposite ends of the longitudinal passage portion. The first end of the prosthetic ligament member extends through the at least one first aperture and the longitudinal passage portion and out of the at least one second aperture to define a first adjustable length. The second end of the prosthetic ligament member extends through the at least one second aperture and the longitudinal passage portion and out of the at least one first aperture to define a second adjustable length. The first and second adjustable lengths extend from the first fastener to the second fastener. 
     A method of repairing an anatomical joint is also disclosed. The method includes operably coupling a first fastener to a first bone portion of a patient and operably coupling a second fastener to a second bone portion of the patient. The method further includes intraoperatively adjusting a tension of a prosthetic ligament member that is a flexible, integrated one-piece member directly coupled to both the first and second fasteners. The prosthetic ligament member has an outer wall that defines a hollow longitudinal passage portion. The first end extends into the longitudinal passage portion through the outer wall and out of the longitudinal passage portion through the outer wall to define a first adjustable length. The second end extends into the longitudinal passage portion through the outer wall and out of the longitudinal passage portion through the outer wall to define a second adjustable length. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a side view, partially in section, of a prosthetic ligament system according to various teachings of the present disclosure; 
         FIG. 2A  is a top view of a prosthetic ligament member of the system of  FIG. 1  shown in an unlooped state; 
         FIG. 2B  is a top view of the prosthetic ligament member of the system of  FIG. 1  shown in a looped state; 
         FIG. 2C  is a top view of the prosthetic ligament member of the system of  FIG. 1  according to additional exemplary embodiments; 
         FIG. 2D  is a top view of the prosthetic ligament member of the system of  FIG. 1  according to additional exemplary embodiments; 
         FIG. 3  is a perspective view of a fastener of the system of  FIG. 1 ; 
         FIG. 4  is a section view of the fastener of  FIG. 3  taken along the line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a perspective view of an installation tool of the system of  FIG. 1 ; 
         FIG. 6  is a perspective view of an installation tool of the system of  FIG. 1  according to various additional embodiments; 
         FIG. 7  is a section view of a knee joint during implantation of the system of  FIG. 1 , wherein the prosthetic ligament member thereof has low tension; 
         FIG. 8  is a section view of a knee joint during implantation of the system of  FIG. 1 , wherein the prosthetic ligament member thereof has high tension; 
         FIGS. 9-13  are side views of various fasteners of the system of  FIG. 1  according to various additional embodiments; 
         FIG. 14  is a side view of the system of  FIG. 1  according to various other embodiments; 
         FIG. 15  is a side view of the system of  FIG. 1  according to various other embodiments; 
         FIG. 16  is a detail view of the prosthetic ligament member of  FIGS. 2A through 2D  showing different fibers thereof braided together; and 
         FIG. 17  is a detail view of the prosthetic ligament member of  FIGS. 2A through 2D  according to various additional exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Referring initially to  FIG. 1 , a system  10  for repairing a knee joint is disclosed. For instance, the system  10  can be used for repairing an anterior cruciate ligament (ACL) in some embodiments described in greater detail below. However, it will be appreciated that the system  10  can also be used for repairing any other feature of the knee joint (e.g., repair of a medial or lateral ligament of the knee joint) without departing from the scope of the present disclosure. Additionally, it will be appreciated that the system  10  can be used for repairing ligaments of the foot, ankle, hand, wrist, spine, etc. without departing from the scope of the present disclosure. 
     The system  10  can generally include a prosthetic ligament member  12 , a first fastener  14 , and a second fastener  16 . As shown in  FIG. 8 , and as will be discussed in greater detail, the system  10  can be used, for example, for repairing and/or restoring normal movement of a knee joint to approximate such movement as naturally constrained by anatomical ligaments. More specifically, the first fastener  14  is operable to be connected to a tibia  20  ( FIG. 8 ), and the second fastener  16  is operable to be connected to a femur  18  ( FIG. 8 ). The prosthetic ligament member  12  can be operably coupled to both the first and second fasteners  14 ,  16  to support the tibia  20  and the femur  18  for relative movement, as will be discussed in greater detail below. 
     The prosthetic ligament member  12  can be formed according to Applicants&#39; co-pending U.S. Patent Application Publication No. 2009/0318961, filed Jun. 22, 2009, which is hereby incorporated by reference in its entirety. More specifically, as shown in  FIG. 2A , the ligament member  12  can be elongate and flexible and can extend from a first end  22  to a second end  24 . The ligament member  12  can include an outer wall  23  that defines a hollow longitudinal passage portion  26 , which is disposed between the first and second ends  22 ,  24 . Moreover, the ligament member  12  can include at least one first aperture  28  that extends through the outer wall  23  and that is disposed between the first and second ends  22 ,  24 . Furthermore, the ligament member  12  can include at least one second aperture  30  that extends through the outer wall  23  and that is disposed between the first and second ends  22 ,  24 . More specifically, the first aperture  28  can be disposed adjacent the first end  22 , and the second aperture  30  can be disposed adjacent the second end  24 . In the embodiment illustrated, the ligament member  12  can include a single first aperture  28  and a single second aperture  30 ; however, it will be appreciated that the ligament member  12  can include a plurality of first apertures  28  and a plurality of second apertures  30 . As discussed below, the first and second apertures  28 ,  30  can allow access into or out of the longitudinal passage portion  26  (i.e., entrance into and/or exit from the longitudinal passage portion  26 ). 
     As shown in the embodiment of  FIG. 2B , the first end  22  of the ligament member  12  can extend through outer wall  23  via the first aperture  28  to enter the longitudinal passage portion  26 , and the first end  22  can exit out of the longitudinal passage portion  26  through the outer wall  23  via the second aperture  30 . Likewise, the second end  24  can extend through the outer wall  23  via the second aperture  30  to enter the longitudinal passage portion  26 , and the second end  24  can exit out of the longitudinal passage portion  26  through the outer wall  23  via the first aperture  28 . It will be appreciated that the first end  22  can enter the longitudinal passage portion  26  through the same aperture (i.e., the first aperture  28 ) that the second end  24  exits the longitudinal passage portion  26 , and the second end  24  can enter the longitudinal passage portion  26  through the same aperture (i.e., the second aperture  30 ) that the first end  22  exits the longitudinal passage portion  26 . As such, the first end  22  can define a first adjustable loop  32  and a first free end  36 . Likewise, the second end  24  can define a second adjustable loop  34  and a second free end  38 . 
     Furthermore, it will be appreciated that the first free end  36  can be pulled away from the longitudinal passage portion  26  to thereby reduce the size of the first adjustable loop  32 . Likewise, the second free end  38  can be pulled away from the longitudinal passage portion  26  to reduce the size of the second adjustable loop  34 . 
     It will be appreciated that the ligament member  12  can be configured differently, and the first and second adjustable loops  32 ,  34  can be formed in any suitable manner. For instance, as shown in  FIG. 2C , the first end  22 ′ can extend into the longitudinal passage portion  26 ′ through the second aperture  30 ′ and can extend out of the longitudinal passage portion  26 ′ through the first aperture  28 ′. More over, the second end  24 ′ can extend into the longitudinal passage portion  26 ′ through the first aperture  28 ′ and out of the longitudinal passage portion  26 ′ through the second aperture  30 ′. 
     Also, as shown in  FIG. 2D , the ligament member  12 ″ can include a plurality of first apertures  28 ″ and a plurality of second apertures  30 ″. For instance, the ligament member  12 ″ can include two first apertures  28 ″ and two second apertures  30 ″. Also, the first apertures  28 ″ and second apertures  30 ″ can be spaced apart on opposite sides of the longitudinal axis of the ligament member  12 ″. As shown, the first end  22 ″ can enter the longitudinal passage portion  26 ″ through one of the second apertures  30 ″ and can exit the longitudinal passage portion  26 ″ through one of the first apertures  28 ″. Also, the second end  24 ″ can enter and exit the longitudinal passage portion  26 ″ through different ones of the first and second apertures  28 ″,  30 ″ respectively. As such, the first end  22 ″ enters the longitudinal passage portion  26 ″ through a different aperture  30 ″ from which the second end  24 ″ exits the longitudinal passage portion  26 ″, and the second end  24 ″ enters the longitudinal passage portion  26 ″ through a different aperture  28 ″ from which the first end  22 ″ exits the longitudinal passage portion  26 ″. 
     It will be appreciated that the ligament member  12 ,  12 ′,  12 ″ can include any suitable number of adjustable loops  32 ,  32 ′,  32 ″,  34 ,  34 ′,  34 ″ by extending into and out of the longitudinal passage portion  26 ,  26 ′,  26 ″ any suitable number of times. Also, it will be appreciated that the ligament member  12 ,  12 ′,  12 ″ can include any suitable number of apertures  28 ,  28 ′,  28 ″,  30 ,  30 ′,  30 ″. Moreover, the apertures  28 ,  28 ′,  28 ″,  30 ,  30 ′,  30 ″ can be disposed in any suitable location on the ligament member  12 ,  12 ′,  12 ″ (e.g., disposed in alignment along the longitudinal axis of the ligament member  12 ,  12 ′,  12 ″. 
     For purposes of discussion, the system  10  will be discussed largely in relation to the embodiments of the ligament member  12  illustrated in  FIG. 2B . However, it will be appreciated that the system  10  can similarly incorporate any of the embodiments of the ligament member  12 ,  12 ′,  12 ″ shown in  FIGS. 2B-2D  or any other suitable ligament member  12 ,  12 ′,  12 ″ without departing from the scope of the present disclosure. 
     As shown in  FIG. 1 , at least one of the first and second adjustable loops  32 ,  34  can receive at least one of the first and second fasteners  14 ,  16  of the system  10 . Specifically, as shown in  FIG. 1 , both the first and second adjustable loops  32 ,  34  can encircle a portion of the first fastener  14 , and the longitudinal passage portion  26  can be folded over a portion of the second fastener  16 . However, it will be appreciated that the ligament member  12  can be coupled in any suitable manner to both the first and second fasteners  14 ,  16  (e.g., first loop  32  encircling the first fastener  14  and the second loop  34  encircling the second fastener  16 ). By pulling on the first and/or second free ends  36 ,  38 , tension within the first and second adjustable loops  32 ,  34  and longitudinal passage portion  26  of the ligament member  12  can be adjusted (i.e., increased), and the first and second fasteners  14 ,  16  will be urged towards each other. In addition, friction between the first and second free ends  36 ,  38  and the inner surface of the longitudinal passage portion  26  can generally inhibit or lock, in a knotless fashion, the first and second free ends  36 ,  38  from being pulled back toward the longitudinal passage portion  26 , thereby maintaining the desired tension in the ligament member  12 . 
     It will be appreciated that if the ligament member  12 ′ of  FIG. 2C  is used, both the first and second adjustable loops  32 ′,  34 ′ can encircle the first fastener  14 , and the longitudinal passage portion  26 ′ can be folded over the second fastener  16  as described above with relation to the embodiment of  FIG. 2B . However, it will be appreciated that the ligament member  12 ′ can be coupled in any suitable manner to both the first and second fasteners  14 ,  16  (e.g., first loop  32 ′ encircling the first fastener  14  and the second loop  34 ′ encircling the second fastener  16 ). Furthermore, it will be appreciated that the ligament member  12 ″ of  FIG. 2D  can be coupled to the fasteners  14 ,  16  in any of these ways. 
     The prosthetic ligament member  12  can be made out of any suitable material and can be manufactured in any suitable fashion. For instance, the ligament member  12  can be made out of a flexible and biocompatible material. More specifically, the ligament member  12  can be made out of and/or can include fibers of polyethylene, gel-spun polyethylene, polyester, polyetheretherketone (PEEK), poly-para-phenylene terephthalamide, polycaprolactone, Kevlar®, carbon, collagen, polyglycolic acid (PGA), polylactic acid (PLA), polyurethane urea, and/or silk (silk from a silk worm or silk from a spider). In some embodiments, the ligament member  12  can be made out of SERICA material, which is commercially available from SERICA Technologies, Inc. of Medford, Mass. Moreover, in some embodiments, the ligament member  12  can be made out of SPIDREX material, which is commercially available from Neurotex Ltd. in addition, the ligament member  12  can be made out of a material that is injected with a natural and/or artificial collagen. Furthermore, the ligament member  12  can be made out of a partially resorbable material. Additionally, the ligament member  12  can be made out of a material that is treated with a platelet concentration to promote tissue growth. Also, the ligament member  12  can be made out of a material that is easily cuttable with a conventional blade or sharpened edge, once a desired tension is reached in the ligament member  12 . 
     Still further, as shown in  FIG. 16 , the ligament member  12  can be a braided construct made out of a plurality of different fibers  13 ,  15  that are braided together to form a hollow tube. The fibers  13 ,  15  can vary in any of a variety of characteristics. For instance, the second fibers  15  can have a greater diameter than that of the first fibers  13  such that the second fibers  15  protrude from the first fibers  13  and such that the second fibers  15  increase the coefficient of friction of the ligament member  12 . Furthermore, the first and second fibers  13 ,  15  can be made out of or include different materials. Additionally, the first fibers  13  be resiliently extendable in a longitudinal direction, whereas the second fibers  15  can be less resiliently extendable and can have a higher tensile strength (i.e., load-bearing capability). Moreover, the first fibers  13  can be a relatively high-strength fiber with a fixed length (i.e., non-resilient) while the second fibers  15  can be constructed so as to promote tissue growth (e.g., serve as a support for tissue regeneration, etc.). It will be appreciated, however, that the ligament member  12  can include a plurality of the same type of fibers without departing from the scope of the present disclosure. Furthermore, it will be appreciated that the ligament member  12  can have any number of fibers, and those fibers can differ in any suitable fashion. 
     In some embodiments shown in  FIG. 16 , the first and second fibers  13 ,  15  can be wrapped around the longitudinal axis of the ligament member  12 . Also, in some embodiments, the first and second fibers  13 ,  15  can be arranged in a fixed sequence along the longitudinal axis. For instance, the first and second fibers  13 ,  15  can alternate in a one-to-one arrangement along the longitudinal axis, or the first and second fibers  13 ,  15  can be arranged at fixed intervals along the axis. 
     Additionally, in the embodiments of  FIG. 17 , the second fibers  15  can be arranged substantially parallel to the longitudinal axis of the ligament member  12 . Also, the first fibers  13  are wrapped helically about the second fibers  15 . 
     Moreover, the ligament member  12  can be specifically configured for the particular application of the ligament member  12  within the knee joint. For instance, the braiding pattern, the materials, the dimensions, and/or other features of the ligament member  12  can be adapted according to the desired level of tension, the desired load carrying capacity, the desired elasticity (e.g., to simulate the elasticity of natural ligament, the dimensions of the knee joint, etc. In addition, the ligament member  12  can incorporate one or more of the features disclosed in U.S. Patent Publication No. 2005/0119696, filed Feb. 23, 2004 by Walters et al., which is hereby incorporated by reference in its entirety. 
     Also, the ligament member  12  can be manufactured and configured to include the first and second loops  32 ,  34  as shown in  FIG. 2B  before surgery. Because the adjustable loop members  32 ,  34  are already formed, the surgeon can implant the ligament member  12  into the knee joint without having to construct the loops  32 ,  34 . Furthermore, because of the frictionally self-containing characteristic of the looped ligament member  12 , the surgeon need not tie any knots. Accordingly, the ligament member  12  greatly facilitates repair and reconstruction of the knee joint. Also, the ligament member  12  can be relatively compact and can facilitate arthroscopic knee surgery. 
     Referring now to  FIGS. 1, 3, and 4 , the fasteners  14 ,  16  will be discussed in greater detail. For purposes of discussion, it will be assumed that both fasteners  14 ,  16  are substantially similar. Thus, the following discussion of the fasteners  14 ,  16  will apply to both of the fasteners  14 ,  16 . However, it will be appreciated that the fasteners  14 ,  16  could have different features without departing from the scope of the present disclosure. 
     As shown in  FIGS. 3 and 4 , the fasteners  14 ,  16  can include a cylindrical base  40  having a first end  42  and a second end  44 . The base  40  can be hollow to define an interior space  46  therein. The ends  42 ,  44  can be open to the interior space  46 . In some embodiments, the second end  44  can be disposed at an angle, α, relative to the first end  42  ( FIG. 4 ). Moreover, the interior portion of the second end  44  can include a fillet  48  ( FIG. 4 ). As will be discussed, the angle, α, and the fillet  48  of the second end  44  can reduce the likelihood of the fastener  14 ,  16  abrading the ligament member  12 , thereby reducing the likelihood of wear of the ligament member  12 . Also, the angle, α, can reduce the likelihood of the fastener  14 ,  16  intruding into the intra-articular space. 
     Moreover, an outer surface  50  of the base  40  of the fastener  14 ,  16  can be threaded along the longitudinal direction. Thus, as shown in  FIGS. 7 and 8 , the fasteners  14 ,  16  can be threadably and fixably attached to the tibia  20  and femur  18 , respectively. It will be appreciated that the fasteners  14 ,  16  can be additionally attached to the tibia  20  and femur  18  by any additional means, such as bone cement, cross pins, additional fasteners, and the like. 
     As shown in  FIGS. 3 and 4 , the fasteners  14 ,  16  additionally include an attachment portion  52 . In some embodiments, the attachment portion  52  can be a rod or post that extends transverse (e.g., perpendicular to the longitudinal axis of the fasteners  14 ,  16 ). The attachment portion  52  can be fixed at both ends to the interior walls of the base  40 . Furthermore, as shown in  FIG. 4 , the attachment portion  52  can have a circular cross-section; however, the attachment portion  52  can have an ovate cross-section or any other suitable shape. Also, in some embodiments, the attachment portion  52  can be removably attached to the base  40  (e.g., inserted and removed in a direction transverse to the axis of the base  40 ). 
     Still further, the fasteners  14 ,  16  can be polygonal and/or can include at least one flat inner surface  54  (i.e., drive portion). For instance, in the embodiments represented in  FIGS. 3 and 4 , the fasteners  14 ,  16  can include a plurality of flat inner surfaces  54  adjacent the first end  42 . As such, the flat inner surfaces  54  can collectively define an octogonal shape or any other suitable polygon. 
     It will be appreciated that the fasteners  14 ,  16  can have any suitable base  40  for attachment to the tibia  20  or femur  18  of the patient. Furthermore, it will be appreciated that the fasteners  14 ,  16  can have any suitable attachment portion  52  for operably coupling to the ligament member  12 . 
     When attached to the first and second fasteners  14 ,  16  ( FIG. 1 ), the ligament member  12  can be received in the hollow interior space  46  of each in order to operably connect to the respective attachment portions  52 . More specifically, the first and second adjustable loops  32 ,  34  can extend continuously about (and encircle) the attachment portion  52  of the first fastener  14  in order to operably couple to the first fastener  14 . Also, the longitudinal passage portion  26  can wrap, fold, or bend about the attachment portion  52  of the second fastener  16  to operably couple to the second fastener  16 . Accordingly, by pulling on the first and second free ends  36 ,  38 , the surgeon can tension the first and second loops  32 ,  34  and reduce the size of the first and second loops  32 ,  34  in order to tighten and tension the ligament member  12 . This increase in tension can urge the first and second fasteners  14 ,  16  toward each other. Accordingly, when the first and second fasteners  14 ,  16  are attached to the tibia  20  and the femur  18 , the increased tension can draw the tibia  20  and femur  18  together, and the tensioned ligament member  12  can constrain the tibia  20  and femur  18  relative to each other while permitting normal articulation of the knee joint. As such, the ligament member  12  can be used as an artificial prosthesis for replacing an anterior cruciate ligament, a posterior cruciate ligament, or any other suitable ligament. 
     It will be appreciated that the ligament member  12  can be coupled to the fasteners  14 ,  16  in any suitable fashion. For instance, in some embodiments, the first loop  32  can be attached to the first fastener  14 , and the second loop  34  can be attached to the second fastener  16 , or vice-versa. Moreover, the first and second ends  22 ,  24  can be routed through the first and second apertures  28 ,  30  in order to produce any suitable number of loops  32 ,  34 , and those loops can be operably attached to the fasteners  14 ,  16  in any suitable fashion without departing from the scope of the present disclosure. 
     Moreover, it will be appreciated that the system  10  can be manufactured such that the ligament member  12  is preassembled and attached to the first and second fasteners  14 ,  16  before implantation surgery. Accordingly, the surgeon can attach the first and second fasteners  14 ,  16  to the tibia  20  and the femur  18 , respectively, and the ligament member  12  will be substantially in position within the joint for tensioning. Thus, the system  10  can greatly facilitate repair and reconstruction of the knee joint. However, it will be appreciated that the system  10  can be such that the surgeon operably couples the ligament member  12  to the first fastener  14  and/or second fastener  16  intraoperatively without departing from the scope of the present disclosure. 
     Implantation of the system  10  will now be discussed in greater detail with reference to  FIGS. 7 and 8 . For purposes of discussion, the system  10  will be discussed in relation to replacement of an anatomical anterior cruciate ligament; however, it will be appreciated that the system  10  can be used for any suitable ligament in the knee joint. It will be appreciated that the system  10  can be implanted during an arthroscopic surgical procedure. 
     Initially, the surgeon can make one or more incisions in the patient in order to at least partially expose the femur  18  and/or the tibia  20  of the patient. Then, the surgeon can form a bone tunnel  51 , which includes a femur portion  53  and a tibia portion  55 . The bone tunnel  51  can be formed using any suitable tool for removal of bone. More specifically, the surgeon can generally put the knee in flexion and drill through the tibia  20  into the femur  53  to form the tunnel  51 . In some embodiments, the femur portion  53  of the tunnel  51  can be a blind bore. 
     Next, the surgeon can attach and fix the fastener  16  to the femur  18  and the fastener  14  to the tibia  20 . In some embodiments, a tool  56 , such as the type shown in  FIG. 5 , can be used to implant the first and second fasteners  14 ,  16 . The tool  56  shown in  FIG. 5  can include a head  58  with flat surfaces that correspond in shape to the flat interior surfaces  54  of the fasteners ( FIGS. 3 and 4 ). Thus, the head  58  can mate with the flats of the interior surfaces  54 , and the tool  56  can transmit rotational forces about the longitudinal axis of the fastener  14 ,  16  to drivingly rotate the fastener  14 ,  16 . The tool  56  can also include a shaft  61  and a handle portion  63 . Furthermore, in some embodiments, the tool  56  can include a clearance member  60 , such as a groove  62  in the head  58  that provides clearance for the ligament member  12 . More specifically, when the head  58  is mated with the fastener  14 ,  16 , the ligament member  12  can extend along the groove  62  without impinging on the head  58 . Thus, to implant the first and second fasteners  14 ,  16 , the head  58  can be mateably inserted into the inner surface  54  of the respective fastener  14 ,  16 , and the tool  56  can be rotated to threadably advance and attach the respective fastener  14 ,  16  to the tibia  20  or femur  18 . 
     In other embodiments, the first and second fasteners  14 ,  16  can be implanted using the tool  56 ′ shown in  FIG. 6 . The tool  56  includes a slot  64 ′ and a clearance member  60 ′ such as a cannula  66 ′ that extends longitudinally through the tool  56 ′. Thus, during implantation, the tool  56 ′ can mate with the respective fastener  14 ,  16 , and the slot  64 ′ can receive the attachment portion  52  of the respective fastener  14 ,  16  in order to rotatably engage the fastener  14 ,  16 . Also, the ligament member  12  can be received within the cannula  66 ′ during installation. It will be appreciated that the tool  56 ′ can engage either end of the fasteners  14 ,  16  for greater versatility. 
     Assuming the ligament member  12  has already been coupled to both the first and second fasteners  14 ,  16 , the free ends  36 ,  38  can extend out of the tibial portion  55  of the tunnel  51 , away from the femur  18 . In other embodiments, both free ends  36 ,  38  can extend out of the femoral portion  53  of the tunnel  51 , away from the tibia  20 . In still other embodiments, one of the free ends  36  can extend out of the tibial portion  55  of the tunnel  51 , and the other free end  38  can extend out of the femoral portion  53  of the tunnel  51 . 
     The surgeon can then pull on the first and second free ends  36 ,  38  to reduce the length of (i.e., eliminate slack in) the ligament member  12  and increase tension in the ligament member  12 . Accordingly, the femur  18  and the tibia  20  can draw together and the ligament member  12  can be tensioned to support relative movement of the femur  18  and the tibia  20 . Once the proper length and tension has been achieved, the surgeon can cut the first and second free ends  36 ,  38 . 
     It will be appreciated that the fasteners  14 ,  16  of the system  10  can be made out of any suitable type, other than those shown in the embodiments of  FIGS. 1-8 . For instance,  FIGS. 9-15  show additional features of the first and second fasteners that can be included within the system  10 . 
     For instance,  FIG. 9  shows fastener  114 ,  116  of the system  110 . Although only one fastener  114 ,  116  is shown in  FIG. 9 , it will be appreciated that each of the first and second fasteners  114 ,  116  can be similar to the illustrated embodiments. It will also be appreciated that components that are similar to the embodiments of  FIGS. 1, 3, 4, 7, and 8  are identified with corresponding reference numerals increased by 100. 
     The fasteners  114 ,  116  can include an elongate base  140  and an attachment portion  152  that is attached to the base  140 , similar to the TOGGLELOC™ fastener, which is commercially available from Biomet, Inc. of Warsaw, Ind. The base  140  and the attachment portion  152  can be made out of a substantially rigid material, such as a biocompatible metal, ceramic, polymer, or a composite thereof. More specifically, the fastener  114 ,  116  can be made out of titanium, cobalt chrome (CoCr), stainless steel, polyether ether ketone (PEEK), and/or RADEL polyphenylsulfone (PPSU). Furthermore, the fasteners  114 ,  116  can be of a type disclosed in Ser. No. 11/203,481 filed Aug. 12, 2005, now U.S. Patent Publication No. 2005-0277961, published Dec. 15, 2005, which is incorporated herein by reference in its entirety. 
     Also, the attachment portion  152  can be an eyelet that is integrally attached to the base  140  at a middle portion thereof. The ligament member  112  can be received in and threaded through (e.g., looped or partially wrapped around) the attachment portion  152 , similar to the embodiments of  FIGS. 1-8 . 
     In addition, the fasteners  114 ,  116  can have a first position (shown in phantom lines) in which the base  140  is operable to move within the bone tunnel  151 . The fasteners  114 ,  116  can also have a second position (shown in solid lines), in which the base  140  is operable to seat against the bone  118 ,  120  outside of the bone tunnel  151 . More specifically, the base  140  can have a width W that is greater than the width W′ of the bone tunnel  151 . Thus, in the second position, the base  140  can be arranged so as to be transverse (e.g., perpendicular) to the axis X of the bone tunnel  151  in order to seat against the bone  118 ,  120 . Also, in the first position, the base  140  can be arranged so as to be substantially aligned with the axis X of the bone tunnel  151  in order to move along the axis X of the bone tunnel  151 . 
     Accordingly, during implantation of the system  110 , the fastener  114 ,  116  can be moved along the axis X of the bone tunnel  151  in the first position, thereby pulling the ligament member  112  along the axis X. Then, once the fastener  114 ,  116  emerges from the tunnel  151 , the fastener  114 ,  116  can be turned to the second position to seat against the bone  118 ,  120 . 
     Referring now to  FIG. 10 , additional features of the fasteners  214 ,  216  are illustrated. Features that are common to those of the embodiments of  FIGS. 1-8  are indicated with corresponding reference numerals increased by 200. 
     As shown in  FIG. 10 , the fasteners  214 ,  216  can include an elongate cross pin  270 . The pin  270  can be embedded within and attached to the femur  218  or tibia  220 . More specifically, the pin  270  can extend transversely to the axis X of the bone tunnel  251 , and can extend across the bone tunnel  251  to be secured at both ends in the femur  218  or tibia  220 . Furthermore, the ligament member  212  can extend about the pin  270  in order to operably attach to the pin  270 . It will be appreciated that the fastener  214 ,  216  can include various features to those disclosed in Ser. No. 11/059,869 filed Feb. 16, 2005, now U.S. Patent Publication No. 2005-0149187, published Jul. 7, 2005, which is hereby incorporated by reference in its entirety. 
     Referring now to  FIG. 11 , additional features of the fasteners  314 ,  316  are illustrated. Features that are similar to the embodiments of  FIGS. 1-8  are indicated with corresponding reference numerals increased by 300. 
     The fasteners  314 ,  316  can include a base  340  that is disk-shaped and attachment portion  352  (e.g., an eyelet) that is integrally attached to the base  340 , so as to be monolithic. The diameter D of the base  340  can be greater than the diameter D′ of the bone tunnel  351 . Accordingly, the base  340  can seat to the bone  318 ,  320  to thereby secure the base  340  to the bone  318 ,  320 . Moreover, the ligament member  312  can be received within and can extend through the attachment portion  352 . More specifically, the attachment portion  352  can extend continuously about the ligament member  312  to thereby encircle the ligament member  312 . As such, the attachment portion  352  can inhibit movement of the ligament member  312  outside of the attachment portion  352 . As stated above, the ligament member  312  can be manufactured and supplied to the surgeon pre-attached to the attachment portion  352 . Alternatively, the system  310  can be employed such that the surgeon threads the attachment portion  312  through the attachment portion  352  intraoperatively. 
     Referring now to  FIG. 12 , additional features of the fasteners  414 ,  416  are illustrated. Components that are similar to the embodiments of  FIGS. 1-8  are indicated with corresponding reference numerals increased by 400. 
     The fasteners  414 ,  416  can include a base  440  and an attachment portion  452 . The base can be substantially disk-shaped and can have a diameter D that is greater than the diameter of the bone tunnel (not shown), such that the base  440  can seat against the bone, similar to the embodiments of  FIG. 11 . The attachment portion  452  can include one or more openings  472  (e.g., notches, slots, etc.) that extend inwardly from the outer periphery of the base  440 . The ligament member  412  can extend over the base  440  and can be received in the openings  472  to be retained therein. For instance, the ligament member  412  can be looped or at least partially wrapped around the base  440  to be received in the openings  472 . It will be appreciated that the openings  472  allow the ligament member  412  to selectively move in and out of the attachment portion  452 . Accordingly, the surgeon can intraoperatively attach and detach the ligament member  412  from the fastener  414 ,  416 . 
     Referring now to  FIG. 13 , additional features of the fasteners  514 ,  516  are illustrated. Components that are similar to the embodiments of  FIGS. 1-8  are indicated by corresponding reference numerals increased by 500. 
     The fasteners  514 ,  516  can be similar to EZLOC™ fasteners, which are commercially available from Biomet, Inc. of Warsaw, Ind. Furthermore, the fasteners  514 ,  516  can include various features of the type disclosed in Ser. No. 12/047,048 filed Mar. 12, 2008, now U.S. Patent Publication No. 2008-0161852, published Jul. 3, 2008, which is hereby incorporated by reference in its entirety. Accordingly, the fasteners  514 ,  516  can include a base  540  and an attachment portion  552 . The attachment portion  552  can receive the ligament member  512 . For instance, the ligament member  512  can loop around or at least partially wrap around the ligament member  512  to attach to the fastener  514 ,  516 . 
     Moreover, the base  540  can be movably (e.g., pivotally) attached to the attachment portion  552 . As such, the fastener  514 ,  516  can be selectively collapsible and extendable. More specifically, in the collapsed position (partially shown in phantom), the base  540  can be rotated relative to the attachment portion  552  such that the fastener  514 ,  516  is substantially aligned with the axis X of the bone tunnel  551 , thereby allowing the fastener  514 ,  516  to move along the axis X of the bone tunnel  551 . In addition, when the fastener  514 ,  516  is extended, the base  540  can be rotated to be substantially perpendicular to the axis X of the bone tunnel  551 , and the base  540  can seat against the femur  518  or tibia  520 . Accordingly, during implantation of the system  510 , the fastener  514 ,  516  can be collapsed and moved through the tunnel  551 , thereby pulling the ligament member  512  along the axis X of the tunnel  551 . Then, when the base  540  sufficiently emerges from the tunnel  551 , the fastener  514 ,  516  can be selectively moved to the extended position, such that the base  540  can be seated. 
     Referring now to  FIG. 14 , additional features of the fasteners  614 ,  616  are illustrated. Components that are similar to the embodiments of  FIGS. 1-8  are indicated with corresponding reference numerals increased by 600. 
     As shown, the fasteners  614 ,  616  can be substantially similar to the embodiments of  FIGS. 1, 3, 4, 7, and 8 . However, the fasteners  614  can include a base  640  and a removably attached attachment portion  652 . It will be appreciated that the fasteners  616  can also include a removably attached attachment portion  652 . The attachment portion  652  can include one or more projections  674 , such as posts, rails, and the like. The projections  674  can be received within a corresponding recess  675 , such as a slot, within the base  640  in order to lock (i.e., key) the attachment portion  652  against rotation about the axis X relative to the base  640 . It will be appreciated that the base  640  could include projections  674  and the attachment portions  652  could include corresponding recesses that receive the projection  674 , without departing from the scope of the present disclosure. It will also be appreciated that the attachment portion  652  could be keyed against rotation about the axis X in any suitable manner. 
     Implantation of the system  610  will be discussed, with the assumption that the ligament member  612  is attached to the second fastener  616  and also to the attachment portion  652  of the first fastener  614 . The first fastener  616  can be threadably attached to the femur (not shown). Similarly, the second fastener  616  can be threadably attached to the tibia (not shown). It will be appreciated that the ligament member  612  could become twisted helically about the axis X during the attachment of the second fastener  616  and/or the attachment of the base  640  of the first fastener  614 . However, because the attachment portion  652  remains detached from the base  640 , the surgeon can untwist the ligament member  612  and subsequently pull on the free ends  636 ,  638  in order to draw the attachment portion  652  into the base  640  and key the attachment portion  652  against rotation about the axis X. As such, the ligament member  612  can be substantially untwisted and yet the ligament member  612  can be securely attached to both the first and second fasteners  614 ,  616 . 
     Referring now to  FIG. 15 , additional features of the fastener  714 ,  716  will be described in greater detail. Components that are similar to the embodiments of  FIGS. 1-8  are indicated by corresponding reference numerals increased by 700. 
     The second fastener  716  can be substantially similar to the second fasteners of the embodiments described above. However, the first fastener  714  can include different features which will be described herein below. It will be appreciated that the second fastener  716  can include the same features as the first fastener  714  without departing from the scope of the present disclosure. 
     The first fastener  714  can include a base  740  and an attachment portion  752 . The attachment portion  752  can be detached and spaced away from the base  740 . Moreover, the system  710  can include a biasing member  776 . The biasing member  776  can be made out of any suitable type, such as a helical spring, one or more Belleville washers (coned-disk spring washer), etc. The biasing member  776  can be disposed between and can abut the base  740  and the attachment portion  752 . Accordingly, the biasing member  776  can bias the attachment portion  752  away from the base  740  to thereby maintain a predetermined amount of tension in the ligament member  712 . 
     It will be appreciated that the prosthetic ligament system of the present disclosure can be attached to the patient&#39;s anatomy using any combination of the fasteners  14 ,  16 ,  114 ,  116 ,  214 ,  216 ,  314 ,  316 ,  414 ,  416 ,  514 ,  516 ,  614 ,  616 ,  714 ,  716  disclosed herein. Moreover, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without departing from the spirit and scope of the disclosure as defined in the following claims. For instance, the sequence of the blocks of the method described herein can be changed without departing from the scope of the present disclosure.