Patent Abstract:
A system of instrumentation and implants for surgically securing an allograft or prosthetic ligament into a patient&#39;s bone is part of a procedure to replace cruciate ligaments. A fixation device for attaching soft tissue to bone includes a fixation mechanism, a shaft, and a securing mechanism. Alternatively, the fixation mechanism may include an expansion leg, the shaft may include a one-way track. In another implementation, the fixation mechanism may include an inner core that expands as a result of insertion of a device that causes radial displacement.

Full Description:
This application claims the benefit of prior provisional application, Provisional Application Ser. No. 60/108,087, filed Nov. 12, 1998. 
    
    
     TECHNICAL FIELD 
     This invention relates to surgical reattachment of soft tissue/ligament to bone, and more particularly, instrumentation for surgically securing an allograft or prosthetic ligament into a patient&#39;s bone as part of a procedure to replace cruciate ligaments. 
     BACKGROUND 
     Surgical re-attachment of soft tissue to bone due to traumatic injury or surgical procedures has created a need for efficient and time-saving instruments, implants, and procedures. Current methods of re-attachment of soft tissue to bone include bone tunnels, surgical staples, surgical tacks, interference screws, and bone anchors. If the desired result is solely approximation of the soft tissue back to the bony insertion site, the aforementioned devices can be used within certain limitations. There are, however, certain tendons and ligaments, which present the surgeon with a very specific set of constraints, for example, grafting of a tendon into the site of an irreparably torn anterior cruciate ligament in the human knee. 
     Each repair technique has a unique set of constraints. For instance, interference screws are difficult to insert and can damage a graft on insertion. In order to insert an interference screw, a large hole must be drilled to accommodate the graft and the screw. The screw prevents bone to tendon fixation around the screw, can leave a weak defect in the bone, and can vascularize the area under compression. In another instance, bone tunnels require additional incisions and trauma to the patient. With a bone tunnel, there is little radial compression on the graft to the bone site and the securing suture may creep or be cut by the bone, and the securing knot may slip. With surgical staples, again additional incisions and trauma to the patient occurs, and there is little radial compression on the graft to the bone site. The surgical staple may even not stay in the bone. In another example, using a device having an internal screw in a tunnel and a ratcheting inner element that presses into the outer screw in anterior cruciate ligament (ACL) repair does not provide radial compression for graft healing. Also, such a device is difficult to revise. 
     SUMMARY 
     A system of instrumentation and implants for surgically securing an allograft or prosthetic ligament into a patient&#39;s bone is used in a procedure to replace a patient&#39;s cruciate ligaments. In one general aspect, a fixation device for attaching soft tissue to bone includes a fixation mechanism, a shaft, and a securing mechanism, which slides along the shaft. The securing mechanism may include an internal one-way locking mechanism. 
     In another aspect, a device for attaching soft tissue to bone includes a shaft, a fixation mechanism attached to the shaft, a one-way track for inserting the shaft therein and the fixation mechanism therethrough; and a securing mechanism for holding a graft within the one-way track by compressing the securing mechanism against the graft. The securing mechanism may be at least one of a conical shape, a cylindrical shape, a cubic shape, or a complex shape capable of exerting an adequate radial force against the graft and into a surrounding bone. The fixation device may include a fixation mechanism with an expansion leg, a shaft with a one-way track, and a securing mechanism. The expansion leg of the fixation mechanism may be single or multiple legs or may be toggles, legs, expansion arms, barbs, tines, or other apparatuses to prevent backward translation. The one-way track of the shaft may be a single length or multiple lengths, i.e., an adjustable length member. The securing mechanism holds the tissue and has an internal one-way lock, which slides along the one-way track. Alternatively, the fixation mechanism may include an inner core that expands as a result of the insertion of a device that causes radial displacement, for example, a wedge, a tapered plug, or a screw. 
     A fixation device may be made of any biocompatible metal, such as titanium or stainless steel, plastic, such as nylon or polyester, or bioabsorbable, such as PLLA. Any material suitable for use in the body can be used. The material must provide adequate resistance to creep, hold the load required, and not be affected by cyclic loading. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a representation of a human knee with an ACL graft held in place, generally in accordance with the fixation device. 
     FIGS. 2A-2T are examples of various fixation mechanisms. 
     FIGS. 3A-3D are various views of the fixation mechanism shown in FIG.  2 A. 
     FIGS. 4A-4D are various views of the fixation mechanism shown in FIG.  2 B. 
     FIG. 5 depicts the fixation mechanism shown in FIG. 2E disposed on a shaft. 
     FIGS. 6A-6D are various views of a securing mechanism. 
     FIG. 7 schematically depicts the shaft and the securing mechanism disposed together. 
     Like reference symbols in the various drawings indicate like elements. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 is a representation of a human knee with an ACL graft  100  (three lines) held in place the joint space between the tibia  90  and the femur  20  by a fixation device. The fixation device includes two fixation mechanisms  110 ,  140  and two securing mechanisms  120 ,  130 . Each fixation mechanism  110 ,  140  has a locking strip (not shown) and is connected to its respective securing mechanism  120 ,  130  by a one-way locking mechanism (not shown). 
     FIGS. 2A-2T are examples of various fixation mechanisms. The fixation mechanism provides resistance to the tensile forces, which are exerted on the graft site. Generally, the length of the fixation mechanism is greater than its width. A fixation mechanism may include a toggle pin member or a toggle element, as shown, for example, in FIGS. 2A-2C. FIG. 2A is a simple toggle fixation mechanism  110  having a parallelogram shaped piece horizontal member  112  (as seen also in FIG. 1) attached to a longitudinal member  114 . The longitudinal member  114 , which is disposed in the insertion tunnel, may be attached to the horizontal member  112  by a pin or screw or the like  116 . 
     FIG. 2B is an alternative form of a simple toggle fixation mechanism  210  that has a rectangular shaped horizontal member  212  attached to a longitudinal member  214  by a pin or screw or the like  216 . The rectangular shaped horizontal member  212  has a plurality of teeth  218  disposed along one side. 
     FIG. 2C is a spring-loaded toggle fixation mechanism  220  that has a parallelogram-shaped horizontal member  222  attached to a longitudinal member  224  by a spring  226 . 
     FIG. 2D is a pull rod fixation mechanism  230  comprised of three longitudinal members  232 ,  234 ,  236 . Two of the three longitudinal members  232 ,  236  have a duck-bill-like head portion  235 ,  237 , which extends over the edge of the insertion tunnel to hold the fixation mechanism in place. 
     FIG. 2E is a self-spring flyout fixation mechanism  240  comprised of two longitudinal members  245  connected together at their base  242 . Each longitudinal member  245  has a duck-bill-like head portion  246 , which extends over the edge of the insertion tunnel to hold the fixation mechanism in place. 
     FIG. 2F is a spring-loaded butterfly fixation mechanism  250  that has a longitudinal member  252  and a butterfly-shaped horizontal member  254  comprised of two arms  256 . The arms  256  of the butterfly-shaped horizontal member  254  are connected together and to longitudinal member  252  by a spring  258 . 
     FIG. 2G is a simple butterfly fixation mechanism  260  that has a longitudinal member  262  and a butterfly-shaped horizontal member  264  comprised of two arms  266 . The arms  266  of the butterfly-shaped horizontal member  264  are connected together and to the longitudinal member  262  by a pin or screw or the like  268 . 
     FIG. 2H is a duck-bill-shaped fixation mechanism  270 . As shown, the head of the fixation mechanism looks like a duck-bill  272  such that the bill portion extends over an edge of the insertion tunnel to hold the fixation mechanism in place. 
     FIG. 2I is a straight jam pin fixation mechanism  280  comprised of a first longitudinal member  282  and a second longitudinal member  284  with a horizontal portion  286 . The horizontal portion  286  extends over an edge of the insertion tunnel to hold the fixation mechanism in place. FIG. 2J is a tapered jam pin fixation mechanism  290  similar to the straight jam pin of FIG.  2 I. However, the interior contacting sides  293 ,  295  of the first longitudinal member  292  and the longitudinal portion of the second longitudinal member  294  are reciprocally tapered. 
     FIG. 2K is a push rod fixation mechanism  300  comprising three longitudinal members  302 ,  304 ,  306 . The two outer longitudinal members  302 ,  306  have respective horizontal portions  303 ,  307  that extend over the edges of the insertion tunnel to hold the fixation mechanism in place. The interior longitudinal member  304  is shaped like a blunt pen tip. The respective longitudinal portions  308 ,  309  of the outer longitudinal members  302 ,  306  are shaped around the blunt pen tip shape of the interior longitudinal member  304 . 
     FIG. 2L is a fixation mechanism  310  formed of guided flexible rods  312 ,  314 . The rods  312 ,  314  each have a horizontal portion  313 ,  315 , which extend over the edges of the insertion tunnel to hold the fixation mechanism in place. 
     FIG. 2M is a swinging cam fixation mechanism  320  with three circular members  322 ,  324 ,  326 , two horizontal members  327 ,  328 , and a block-shaped member  321 , which is disposed in the insertion tunnel. 
     FIG. 2N is a fixation mechanism  330  that includes spring loaded pins  332 ,  334  disposed on a longitudinal member  336 . FIG. 20 is a fixation mechanism  340  that has a single spring-loaded pin  342  disposed on a longitudinal member  344 . FIG. 2P is a fixation mechanism  350  that includes rotary flyouts  352 . 
     FIG. 2Q is a fixation mechanism  360  with a pop rivet  362  disposed on the longitudinal member  364 . FIG. 2R is a one-piece butterfly  370  having a longitudinal member  372  disposed in the insertion tunnel and two arms  374 ,  376  that extend over the respective edge of the insertion tunnel. 
     FIG. 2S is a threaded push rod fixation mechanism  380  similar in shape and form to the push rod fixation mechanism shown in FIG.  2 K. However, threaded push rod fixation mechanism  380  has thread portions  388 ,  389  on the respective interior, contacting portions of outer longitudinal members  382 ,  386  and interior longitudinal member  384 . 
     FIG. 2T is a threaded pull rod fixation mechanism  390  similar in shape and form to pull rod fixation mechanism  230  shown in FIG.  2 D. However, the respective interior contact points of longitudinal members  392 ,  396  and interior longitudinal member  394  have threaded portions  398 ,  399 . 
     FIGS. 3A-3D show various views of the simple toggle fixation mechanism  110  shown in FIG.  2 A. FIG. 3A is a side view of the parallelogram-shaped horizontal member  112  of the fixation mechanism. FIG. 3B is a top end view of the longitudinal member  114  of the fixation mechanism. FIG. 3C is a side elevated view of the parallelogram-shaped horizontal piece  112  of the fixation mechanism. FIG. 3D is a side view of the longitudinal member  114  of the fixation mechanism. 
     FIGS. 4A-4D show various views of the alternative simple toggle fixation mechanism  210  shown in FIG.  2 B. FIG. 4A is a side view of the longitudinal member  214  of the fixation mechanism. FIG. 4B is a side view of the horizontal member  212  of the fixation mechanism. FIG. 4C is an elevated side view of the horizontal member  212  of the fixation mechanism with the teeth  218  exposed. FIG. 4D is a top end view of the longitudinal member  214  of the fixation mechanism. 
     FIG. 5 depicts the fixation mechanism  240  shown in FIG. 2E disposed on a shaft  510 . The shaft  510  has a plurality of raised portions  520  disposed thereon. Referring back to FIG. 1, the shaft  510  is disposed within the insertion tunnel such that the fixation mechanism disposed thereon (in FIG. 1, fixation mechanism  110 ) protrudes from an end of the insertion tunnel. The shaft  510 , for instance, is a one-way track, which has, for example, pins, transverse tracks or bumps, intended to prevent a closely fit external sliding member, such as a securing mechanism, from reversing direction once it has started sliding on the shaft  510 . 
     FIGS. 6A-6D show various views of a securing mechanism  600 . Generally, a securing mechanism  600  has the shape of a plug with cutouts or channels  635 , designed to support tendon grafts without damage, about its circumference, i.e., a support plug. FIG. 6A is a longitudinal side view of the securing mechanism  600 . FIG. 6B is a schematic elevated perspective view of the securing mechanism  600  showing the cutouts  635  in the outer circumference of the securing mechanism  600 . FIG. 6C is a schematic end view of the securing mechanism  600 , showing the cutouts  635 . FIG. 6D is a horizontal side view of the securing mechanism  600 . The securing mechanism could be, for example, a cylindrical, a conical, a cubic, or a complex shape, which provides adequate radial force against the graft into the surrounding bone. The securing mechanism may be made of any biocompatible metal, polymer, bioabsorbable polymer, or bone. If bone is used, an additional securing mechanism must be used to provide the one-way locking on the shaft. The securing mechanism can transport site-specific drugs, such as bone morphing proteins, antibiotics, anti-inflammatories, and anesthetics. 
     FIG. 7 schematically depicts a fixation mechanism  240  on the shaft  510  and the securing mechanism  600  disposed together. The securing mechanism  600  is moved in the direction of the arrow along the shaft  510 , whereby the securing mechanism  600  engages with the shaft  510  to lock in place. 
     The system of instrumentation and devices for attaching soft tissue to bone reduces the operating room time required to perform a procedure. The fixation device can be used in confined spaces, such as those in and around the human knee. The fixation device for attaching soft tissue to bone can be made of bioabsorbable, biopolymer, or biometal and can be easily removed and replaced. The devices can be deployed with one hand and allow the surgeon to individually tension each leg of an ACL graft. Using the system and/or device does not damage ACL grafts and a variety of graft sizes can be accommodated. Both ends of an ACL graft can be inserted through a single incision. Once the graft is in place, the securing mechanism radially presses the graft against the side of the insertion tunnel, maintaining maximum graft to bone area required for optimal healing. There is high resistance to pull out as compared to standard interference screws that are approximately 800 N on the femoral side. 
     The system of instrumentation and devices for surgically securing an allograft or prosthetic ligament in a patient&#39;s bone are used in a procedure to replace a patient&#39;s cruciate ligaments. As part of the replacement procedure for the anterior cruciate ligament, the patient&#39;s leg is bent at an approximately ninety (90°) degree angle and a single incision is made medial to the tibial tuberosity. Through this incision, an insertion tunnel is created at the desired insertion point of the graft using standard orthopaedic techniques. The insertion tunnel exits on the lateral aspect of the femoral cortex. A replacement ligament is prepared using a hamstring allograft. 
     The fixation device is loaded with the graft at full-length extension. The fixation mechanism is pushed into the insertion tunnel until it exits the femoral insertion tunnel. The fixation device is pulled back to allow the fixation mechanism to rotate to prevent further retrograde movement, i.e., in FIG. 1, the horizontal portion of the fixation mechanism  110 , e.g., the toggle, rotates to a horizontal position across the femoral insertion tunnel. The shaft holds the fixation mechanism taut and the securing mechanism is slid forward into the insertion tunnel. Inside the securing mechanism is a one-way locking gate, which prevents retrograde movement of the securing mechanism along the shaft. The securing mechanism also presses the graft against the sidewall of the tunnel to facilitate healing over a larger area. The securing mechanism provides radial force to press the graft against the sidewall of the bone tunnel for faster and more efficient healing. 
     The graft is held in place within the femoral insertion tunnel by compression of the securing mechanism against the graft and is prevented from being pulled out of the insertion tunnel by the fixation mechanism. Once the femoral side of the graft is pressed in place and locked on the shaft, the tibial end of the graft is pulled into position and also locked into place. 
     An insertion instrument allows the surgeon to deploy the fixation device with one hand: position the fixation mechanism, push the securing mechanism, and cut off the excess length of the graft using one hand. 
     A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope. Accordingly, other implementations are within the scope of the following claims.

Technology Classification (CPC): 0