Abstract:
A method of providing a replacement anterior cruciate ligament (ACL) provides a tibial tunnel and at least one femoral tunnel for receiving the replacement ligament, the femoral and tibial tunnels not being colinear but rather in an orientation that more closely mimics the natural ACL. The femoral tunnel is formed through the anterior medial portal. A cross pinning guide having a femoral rod for insertion into the femoral tunnel, a spaced apart arc shaped track and a guide block having one or more bores aligned with the femoral rod whereby an instrument inserted through one of the bores creates a pilot hole for the cross pin which intersects the femoral tunnel and an appropriate angle thereof which avoids ligaments and other sensitive tissue can be selected by adjusting the guide block along the track.

Description:
This application claims the priority benefit of U.S. Provisional Application No. 61/104,431, filed Oct. 10, 2008, the entire contents of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to orthopedic surgery and specifically to arthroscopic repair of soft tissue injuries. 
     BACKGROUND OF THE INVENTION 
     The complete or partial detachment of a ligament, tendon or other soft tissue from an associated bone within the body is a relatively commonplace injury. Tissue detachment may occur as the result of an accident such as a fall, overexertion during a work-related activity, during the course of an athletic event, or in any one of many other situations or activities. Such injuries are generally the result of excess stress being placed on the tissues. 
     In the case of a partial detachment, commonly referred to as a “sprain”, the injury frequently heals itself, if given sufficient time and if care is taken not to expose the injury to undue stress while healing. If, however, the ligament or tendon is completely detached from its associated bone or bones, or if it is severed as the result of a traumatic injury, partial or permanent disability may result. Fortunately, a number of surgical procedures exist for re-attaching such detached tissues, as well as for completely replacing severely damaged tissues with grafts that may be formed from tissue harvested from elsewhere in the patient&#39;s body (an autograft), from another human (an allograft) or from an animal (a xenograft), or may be synthetic in origin. 
     A damaged anterior cruciate ligament (“ACL”) in a human knee is commonly replaced with a graft ligament by first forming bone tunnels in the tibia (“tibial tunnel”) and femur (femoral tunnel”) at nominally the points of normal attachment of the native ACL. An end of the graft ligament (which may, but not necessarily terminate in a bone block) is passed through the tibial tunnel and into the femoral tunnel, positioning the graft to span the joint space in the knee between the tunnels. The ends of the graft are then fixed in the respective tunnels. Several methods and devices for fixing the graft ligament in the femoral and tibial tunnels are known, including various types of ligament or suture anchors, buttons and staples for attaching objects to bone. 
     One known method for anchoring bone blocks in bone tunnels is through “cross-pinning”, in which a pin, screw or rod is inserted into the bone, transversely to the bone tunnel, so as to intersect the graft ligament (or bone block, if present), to “cross-pin” the graft in the bone tunnel. The cross-pin (i.e., the aforementioned pin, screw or rod) is generally placed in a pre-drilled passageway that is prepared using a drill guide. Methods and apparatus for effecting ACL repairs that include the use of cross-pinning drill guides are disclosed in commonly assigned U.S. Pat. Nos. 5,849,013; 6,066,173; 6,113,604; 6,379,384; 6,517,546; 6,540,783; 6,716,217; 6,958,067; 7,056,340 and 7,195,642, and U.S. patent application Ser. Nos. 10/404,685; 10/436,018; 10/436,038; 11/088,250 and 11/343,141, the contents of which are hereby incorporated by reference in their entirety. 
     Considerations for cross-pinning graft ligaments in the tibia differ from considerations for cross-pinning of graft ligaments in the femur. These considerations include differences in anatomical geometry, bone quality, and other considerations. These different requirements generally result in the development and application of different cross-pinning guides for femoral and tibial cross-pinning, adding complexity and expense to the performance of ACL replacement surgeries. Further, native ACLs include two functionally distinct components, the anteromedial and posterolateral bundles, and fully anatomic reconstructions of an ACL to restore the kinematics of a natural knee joint may require separate tunnels to be drilled and potentially cross-pinned for each component of the ACL, further increasing the complexity of the surgery and the requirement for multiple cross-pinning guides. 
     In addition, known femoral cross-pinning guides and methods for their application generally require that the femoral and tibial tunnels are substantially aligned with one another, so that a portion of the femoral guide can be passed linearly through the tibial tunnel and into the femoral tunnel for positioning femoral cross pins. This requirement for substantial alignment of the tibial and femoral tunnels does not necessarily provide optimal positioning of the replacement ligament, or ligament bundles, thereby limiting the surgeon&#39;s ability to provide fully anatomical positioning of a replacement ACL. 
     Accordingly, there exists a need for improved methods and apparatus for anatomical replacement of an ACL ligament in a knee. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a method for replacing an ACL in a human knee by cross-pinning opposite ends of one or more graft in respective femoral and tibial bone bores. In an aspect of the present invention, the femoral and tibial tunnels have independently established axes and are cross-pinned using a universal cross-pinning guide. In an embodiment, the guide includes interchangeable guide pins for aligning the cross-pinning guide with respective femoral and tibial tunnels. While employing the guide for the femoral tunnel the guide pin used therefor need not also be inserted into the tibial tunnel. 
     In another aspect of the invention, a method for performing an ACL replacement using two ACL graft bundles is provided. In this method, two femoral and two tibial tunnels are provided, and the universal cross-pinning guide is used to guide the cross-pinning of graft ligament portions in each bone bore. In yet another aspect of the present invention, a tibial tunnel for cross-pinning is provided from outside the body, through the tibia and into the joint space between the tibia and the femur, while the femoral tunnel for cross-pinning is provided from within the joint space, into and at least partially through the femur. 
     This invention is described with particularity in the appended claims. The above and further aspects of this invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a cross-pinning guide according to the present invention, for use in cross-pinning a graft in a tibial tunnel or in a femoral tunnel; 
         FIG. 2  is a side elevation view of components and tools used with the cross-pinning guide of  FIG. 1 ; 
         FIG. 3  is a perspective view of the cross-pinning guide of  FIG. 1  in use for cross-pinning a femoral bone tunnel prepared via an anteromedial arthroscopic portal; 
         FIG. 4  is a perspective view of the use of the cross-pinning guide of  FIG. 1  in use for cross-pinning a tibial bone tunnel; 
         FIG. 5  is a front elevation view of an ACL graft cross-pinned in a knee using methods of the present invention; and 
         FIG. 6  is a front elevation view of a dual-bundle ACL graft cross-pinned in a knee using methods of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring more particularly to the figures,  FIG. 1  illustrates a cross-pinning guide  100  for use according to a method of the present invention, for cross-pinning an ACL graft in a bone tunnel, for example, in either a tibial tunnel or a femoral tunnel in a knee joint. Turning also to  FIG. 2 , a number of components and tools  200  are associated with the cross-pinning guide  100 , as referenced hereinbelow. The cross-pin guide  100  comprises an L-shaped member  102  having a base  104  and an arm  106 . The arm  106  extends transversely to, and preferably normal to the base  104 . In an embodiment, the arm  106  is provided with a ruled scale along at least a portion of its length. 
     An interchangeable tunnel guide rod  108  is removably mountable to the base  104 , near a first end  110  of the guide rod  108 , and oriented parallel to the arm  106 . The guide rod  108  is preferably provided to a surgeon in a kit including a plurality of guide rods  108  having a selection of lengths and diameters to accommodate various graft sizes and patient anatomies. Two mounting holes  112  are provided in the base  104  for receiving the guide rod  108 , one of the two mounting holes  112  being for use of the drill guide  100  on a left knee and the other for use on a right knee. The rotational orientation of the guide rod  108  in either mounting hole  112  is fixed via a slot  114  adjacent the respective mounting hole  112 , and a mating pin  116  near the first end  110  of the guide rod  108  (see  FIG. 2 ). In a preferred embodiment, the guide rod  108  is cannulated along its length for placement on a guidewire (not shown). The guide rod  108  may be retained in the respective mounting hole  112  via a locking knob  118  that may activate a spring-loaded detent, a retaining screw, or another retention means. In a preferred embodiment, a kit is provided including a plurality of guide rods sized for various locations and sizes of bone tunnels. 
     The cross-pin guide  100  further comprises an arced rail assembly  120  slidably mounted to the arm  106 . The arced rail assembly  120  can be locked in position along the arm  106  using a locking device  122  that in a preferred embodiment includes a knob  124  connected to a locking screw that engages the arm  106  when tightened. The locking screw may also be spring-loaded for positive engagement with one or more detents  126  provided along the arm  106  for preferred positioning of the arced rail assembly  120  along the arm  106 . 
     The arced rail assembly  120  includes an arced rail  128  having a substantially circular arc that is centered about a position within a diametrical, longitudinally-elongated passageway  130  in the tunnel guide rod  108 , near a second end  132  of the guide rod  108 , opposite the first end  110 . On larger diameter sizes of the guide rod  108  the passageway  130  can extend all the way through the guide rod  108 . Mounted to and positionable along the arced rail  128  is a guide block  134  that includes two bores  136 ,  138 , each of which can slidably receive a trocar sleeve  140 . 
     One trocar sleeve  140  is shown positioned in the bore  136  in  FIG. 1 . The second bore  138  provides for placing two cross-pins across a bone tunnel. Descriptions herein for the installation of one cross-pin intersecting a bone tunnel apply equally to the installation of two cross-pins intersecting the bone tunnel. The trocar sleeve  136  is axially and rotatably movable in the bore  136  and, as also illustrated in  FIG. 2 , is provided with a collar portion  142  having a diametrically extending slot  144  formed therein. 
     A trocar  146 , slidably disposable in the trocar sleeve  140 , is provided with a sharp tip  148  for penetration of bone. A transversely-extending pin  150  is provided near, but spaced from, the end of the trocar opposite the sharp tip  148 . The pin  150  is fixed in place in the trocar  146  and is received by the slot  144  in the trocar sleeve collar  142  such that axial (in a distal direction) and rotational movement of trocar  146  causes similar movement of sleeve  140 , for drilling the trocar  146  and sleeve  140  together into bone. Preferably, the trocar  146  and sleeve  140  are drilled far enough into the bone to enter the passageway  130 . 
     A cross-pin  152  (see  FIG. 2 ) is slidable through the trocar sleeve  140  for insertion into bone using an insertion tool  154 . The insertion tool  154  has a cross-pin insertion tip  156 , a handle  158  that can be struck with a mallet for inserting the cross pin through the trocar sleeve  140 , and a step-in diameter  160  for controlling the depth of insertion of the cross-pin  152 . The guide block  134  includes upper  162  and lower  164  components held together via a screw  166  so that the drill guide  100  can be disassembled from the trocar sleeves, leaving the trocar sleeves positioned in bone for insertion of cross-pins. In another preferred embodiment, the guide block  134  is configured for the direct placement of cross-pins, without the use of trocar sleeves and trocars. In this case, the cross-pins are inserted through, and guided by the bores  136 ,  138  in the guide block. 
     The present invention can be practiced with cross-pins  152  of any type, and is independent of the type of cross-pins used in a surgical procedure. The cross-pins  152  may be polymeric, a bioceramic, a composite, or made of non-absorbable materials. Preferably, the cross-pins  152  are formed of a bio-absorbable material. Accordingly, the ACL reconstruction will hereinafter be discussed in the context of using absorbable cross-pins, and in the context of using preferred apparatus for deploying such absorbable cross-pins  152 . Preferred materials include poly(lactic acid) with tri-calcium phosphate and copolymer of lactide and glycolide (poly(lactide-co-glycolide)) with tri-calcium phosphate. 
     In an ACL replacement procedure of the present invention, the patient is prepared for arthroscopic knee surgery using standard techniques. An anterolateral (AL) arthroscopic viewing portal is created in the patient&#39;s knee, as well as an anteromedial (AM) working portal. These standard surgical portals are not illustrated in the Figures. Also not shown in the Figures are skin incisions required for preparing a tibial tunnel or other steps in an ACL replacement procedure. After confirmation of an ACL tear requiring ligament replacement, a suitable graft is provided, for example, through harvesting a semitendinosus graft from the patient, or by providing an allograft, although any type and source of ACL graft can be implanted using the methods of this invention, including soft tissue grafts and grafts terminated with bone blocks or substitute rigid materials. 
       FIG. 3  schematically illustrates femoral cross-pinning  300  according to the present invention. Referring to  FIG. 3 , there is shown a human knee joint  302  including a femur  304  and a tibia  306 , each prepared according to known surgical methods with a respective femoral tunnel (also known as a femoral tunnel)  308  and tibial tunnel (also known as a tibial tunnel)  310  appropriate for receiving an ACL replacement graft (not shown in  FIG. 3 ), and a joint space  312  between the femur  304  and the tibia  306 . The tibial tunnel  310  extends from outside the patient, through an incision in the skin, through the tibia  306  and into the joint space  312  at substantially the native ACL attachment location on the tibial plateau  314 . Exemplary of preparation of the tibial tunnel  310 , a drill guide known in the art is first used to pass a guide pin along a tibial tunnel axis  316  for the tibial tunnel  310 , followed by reaming along the guide pin to a diameter appropriate for receiving the graft. 
     The femoral tunnel  308  is also prepared using known methods. At a position in the femoral notch  318  that the surgeon determines is appropriate for the insertion of the graft, a guide pin is first drilled into the femur  304  along a selected femoral tunnel axis  320  via the anteromedial (AM) portal, followed by reaming to create a femoral tunnel  308  along the guide pin to an appropriate depth and diameter for receiving the graft. Importantly, preparing the femoral tunnel  308  via the AM portal enables the surgeon to establish the best anatomical position and axis for the femoral tunnel  308 , independently of the preparation and position of the tibial tunnel. To better attain kinematically optimal surgical outcomes, two functionally distinct component grafts comprising replacements for native ACL components: the anteromedial and posterolateral bundles, can be independently implanted and cross-pinned using the methods of the present invention, using two bores provided in one or both of the femur and the tibia, and generally using two bores in each of the femur and the tibia. Various guides have been developed for preparing multiple bone bores for these procedures, which are variously referred to as “dual-tunnel,” “dual-bundle,” “double-bundle” or “double tunnel” procedures. It is to be understood that the methods described herein are equally applicable for cross-pinning grafts or graft components in any number of bone bores during an ACL replacement procedure, whether employing a single ACL replacement graft, or multiple graft components and a correspondingly larger number of bone bores for cross-pinning. 
     The present invention allows a surgeon to reliably align a proper cross pin orientation into a tunnel formed through the AM portal, which heretofore was difficult or impossible with prior cross pinning guides. With the tibial  310  and femoral  308  tunnels prepared, an appropriately sized femoral guide rod  307  is mounted to the cross-pin guide  100 . The guide rod  307  is then inserted through the AM portal into the femoral tunnel  308  only and not inserted into the tibial tunnel. The surgeon chooses a femoral cross-pinning angle to avoid or minimize any damage to soft tissues including but not limited to medial collateral ligament, lateral collateral ligament, popliteal tendon, and quadriceps muscle. The surgeon palpates the knee to locate the cartilage around the joint, and positions the guide head  134  along the arced rail  128  superior to the cartilage. In an embodiment, the guide head  134  is positioned along the arced rail  128  approximately twenty degrees superior to a zero-angle marking  322  on the arced rail  128 . Then at least one femoral trocar sleeve  324  is drilled into the femur using the method described hereinabove. Depending on the required repair, the surgeon decides whether the cross-pinning will be done from the medial side (as illustrated in  FIG. 3 ) or the lateral side of the knee joint  302 . The cross-pin guide  100  is then removed from the femur  304 , leaving the at least one femoral trocar sleeve  324  in place in the femur. 
     To verify the accuracy of placement of the at least one femoral trocar sleeve  324  in the femur  304 , the surgeon can use an arthroscope to look along the femoral tunnel  308  from the joint space  312  while inserting a guide pin (not shown) through the femoral trocar sleeve  324 , to visualize the guide pin as it enters the femoral tunnel  308 . 
     The femoral guide rod  307  for the femoral tunnel is then unmounted from the cross-pinning guide  100  and replaced with an appropriately-sized tibial guide rod  402  for tibial cross-pinning, as shown in  FIG. 4 , which illustrates the knee joint  302  from a different perspective from that of  FIG. 3 . In  FIG. 4 , the tibial guide rod  402  is inserted into the tibial tunnel  310  from outside the patient toward the joint space  312 . Depending on the anatomy of the patient&#39;s knee and other factors, the surgeon decides whether the cross-pinning will be done from the medial side (as illustrated in  FIG. 4 ) or the lateral side of the knee joint  302 . The surgeon then establishes the correct tibial cross-pinning angle and positions the guide head  134  appropriately along the arced rail  128  inferior to the zero-angle marking  322  on the arced rail. In an embodiment, the guide head  134  is positioned along the arced rail  128  approximately twenty degrees inferior to the zero-angle marking  322  on the arced rail  128 . Then at least one tibial trocar sleeve  404  is drilled into the femur using the method described hereinabove. The cross-pin guide  100  is then removed from the tibia  304 , leaving the at least one tibial trocar sleeve  404  in place in the tibia. 
     To verify the accuracy of placement of the at least one tibial trocar sleeve  404  in the femur  304 , the surgeon can use an arthroscope to look along the tibial tunnel  310  while inserting a guide pin (not shown) through the trocar sleeve  404 , to visualize the guide pin as it enters the tibial tunnel  310 . 
       FIG. 5  schematically illustrates an example of a single-bundle graft placement  500  in a knee. Referring to  FIG. 5 , an ACL graft  502  is shown, having a first end portion  504  positioned in the tibial tunnel  310  and a second end portion  506  positioned in the femoral tunnel  308 . Referring to  FIGS. 3 ,  4  and  5 , once the placement accuracy of the femoral  324  and tibial trocar sleeve  404  has been verified and the graft  502  has been prepared for implantation, a first end portion  504  of the graft (or graft component for a dual bundle procedure) is positioned in the tibial tunnel  310  and a second end portion  506  of the graft  502  is positioned in the femoral tunnel  308 . Methods for preparing a graft for implantation and for positioning a graft in a bone bore are well known in this art. For example, the graft may be positioned in a bone bore by using a passing pin, placed through a guide hole formed during the preparation of a bone bore, to pull the graft into the bore via a suture attached between the graft and the passing pin. 
     The graft  502  can be positioned by passing the second end portion  506  of the graft  502  through the tibial tunnel  310 , across the joint space  312  and into the femoral tunnel  308 , leaving a central portion  508  of the graft  502  spanning the joint space  312 . Alternatively, the graft  502  can be positioned in the femoral  308  and tibial tunnel  310  entirely from the joint space  312 , by passing the first end  504  of the graft  502  into the tibial tunnel  310 , and passing the second end portion  506  into the femoral tunnel  308 , leaving the central portion  508  spanning the joint space  312 . 
     With the graft  502  properly positioned in the knee, one or more femoral cross-pins  510  are then inserted transversely through the second end portion  506  of the graft in the femoral tunnel  308  via a respective trocar sleeve  324  (not shown in  FIG. 5 ) using the insertion tool  154 , to fix the graft  502  in the femoral tunnel  308 . Once the femoral cross-pin  510  has been satisfactorily positioned in the femoral tunnel  308  and second end portion  506  of the graft  502  for cross-pinning, the respective trocar sleeve is removed from the femur  304 . In an alternate embodiment wherein a replacement ACL graft terminates in a bone block, for example, for implanting a bone-tendon-bone (BTB) graft, the an additional drilling step may be required after the graft has been placed in the femoral tunnel  308 . This additional drilling step can be performed by passing a stepped-diameter trocar through the respective trocar sleeve positioned in bone for receiving a cross-pin, and through the graft, before inserting the cross-pin. 
     Once the second end  506  of the graft  502  has been cross-pinned in the femoral tunnel  308 , the graft  502  is tensioned along its length, and the first end portion  504  of the graft  502  is cross-pinned in the tibial tunnel  310 , using one or more tibial cross pins  512  in the same manner as the second end portion  506  of the graft  502  was cross-pinned in the femoral tunnel  308 , to complete the repair. As can be seen clearly in  FIG. 5  and discussed hereinabove, the tibial tunnel axis  316  and the femoral tunnel axis  320 , having been independently established by the surgeon, can be non-collinear or non-intersecting, to provide optimal positioning for an anatomic replacement of a native ACL. Depending on the position of the knee joint during or post-surgery, the tibial and respective femoral tunnels  310  and  308  for a graft ligament may be in axial or near-axial alignment with one another, despite the respective bores having been independently established during surgery. 
     The methods of the present invention can be used to perform a dual-bundle ACL replacement surgical procedure.  FIG. 6  schematically illustrates an example of a completed dual-bundle graft placement  600  that may be performed in a knee  602  having a tibia  604  and a femur  606 . As seen in  FIG. 6 , an anteromedial graft component  608  is implanted in the knee  602 , and fixed in a femoral tunnel  610  and a tibial tunnel  612  using cross-pins  614 . A posterolateral graft component  616  is also implanted in the knee  602 , and fixed in respective femoral  618  and a tibial  620  bores using cross-pins  614 . As illustrated in  FIG. 6 , two cross-pins  614  are used in each of the bores  610 ,  612 ,  618 ,  620 . In another embodiment, one cross-pin  614  is used to fix each of one or more graft component in a respective bore. 
     The method of the present invention provides several advantages over prior ACL replacement methods. The use of an AM portal for preparing one or more femoral tunnel enables the surgeon to better anatomically place the femoral and tibial tunnels independently of one another, without the constraint of prior cross-pinning repair methods that require the femoral and tibial tunnels to be substantially aligned for receiving a femoral cross-pinning guide that must pass through the tibial tunnel to access the femoral tunnel. In addition, use of a universal cross-pinning guide that can be applied to both tibial and femoral tunnels, provides a unified and simplified surgical instrument set that may enable surgeons to achieve more consistent results and cost reductions for patients. 
     Further, there is increasing interest in performing ACL replacement surgeries using separate anteromedial and posterolateral replacement ligament components, to provide more closely anatomical and more fully kinematically functional repairs. These double-bundle repairs also generally require additional bone tunnels to be drilled to accommodate the additional graft components. The cross-pinning methods and guide of the present invention enable the surgeon to provide multiple tunnel, cross-pinned graft replacements in a straightforward manner. 
     While the invention has been particularly shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.