Abstract:
A tibiotalar fusion system includes that includes a curved fusion nail and interlocking fasteners, along with delivery instrumentation. The curved ankle fusion nail is delivered with the fasteners in such a manner that the curved ankle fusion nail does not pass through the subtalar (talocalcaneal) joint. The curved fusion nail thus preserves the subtalar (talocalcaneal) joint and the natural motion of the hindfoot within a mammal such as, for example, a human. Additionally, drill guided delivery instrumentation and surgical methods of delivering and fixing the curved tibiotalar nail within a desired anatomical location such as the ankle.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of the filing date of U.S. Provisional Application No. 61/957,433, filed on Jul. 2, 2013. U.S. Provisional Application No. 61/957,433 is hereby incorporated by reference. 
     
    
     FIELD OF DISCLOSURE 
       [0002]    The present application generally relates bone fusion systems and methods, and more particularly, to bone fusion nails for repairing or treating an injury to an ankle joint area or a degenerative joint disease affecting an ankle joint area, instruments for delivering bone fusion nails and surgical methods of using bone fusion nails. 
       BACKGROUND 
       [0003]    Painful degenerative joint disease of the ankle can be caused by many conditions including osteoarthritis, rheumatoid arthritis, trauma and deformity. These conditions are typically treated by surgical methods including fusion with screw fixation, fusion with intramedullary nailing, or a total ankle arthroplasty. Each of these choices presents significant problems. For instance, a screw used in fusion screw fixation may loosen over time and result in loss of fixation. Fusion screw fixation also involves a risk of screw migration or breakage, and may necessitate prolonged post-operative non-weight-bearing limitations on the patient. Traditional intramedullary nailing options may provide a stronger construct than fusion screw fixation and permit earlier post-operative weight-bearing activities by the patient. However, traditional intramedullary nails span the subtalar (talocalcanel) joint and thus destroy the subtalar (talocalcaneal) joint. This aspect of traditional intramedullary nails severely limits motion of the hindfoot and makes it difficult to walk, especially on uneven surfaces. Another problem with traditional intramedullary nails is that such nails transfer a significant amount of stress to other joints of the foot, which can lead to degeneration of these joints, additional pain, and in some cases, require further surgical intervention. Because total ankle arthroplasty typically has an unacceptably high failure rate, ankle fusion is generally viewed as a more reliable choice for the treatment of degenerative joint disease of the ankle. 
         [0004]    Currently available intramedullary nailing options, while better than most other treatment options, each require the fusion nail to be inserted through the heel bone or calcaneus bone, through the subtalar (talocalcaneal) joint, up through the talus bone, through the tibiotalar joint, and into the tibia. A need therefore exists for devices and methods for delivering a secured fusion nail that bypasses and preserves the subtalar (talocalcaneal) joint. 
       SUMMARY 
       [0005]    A tibiotalar fusion system is disclosed that allows for the bypass of the subtalar (talocalcaneal) joint and includes a curved fusion nail and interlocking fasteners along with delivery and targeting instrumentation. The fasteners are used to secure the placement of the curved fusion nail in a desired anatomical location. The curved fusion nail is dimensioned so that it does not pass through the subtalar (talocalcaneal) joint, and thus preserves the subtalar joint and the natural motion of the hindfoot within a mammal, such as, a human. 
         [0006]    Also disclosed are delivery instruments such as drill guide jigs that facilitate placement of the curved fusion nail within a desired location, such as an ankle joint area, and allow for precise specific fastener placement within the curved fusion nail. 
         [0007]    Further disclosed are surgical methods of using the curved fusion nail for repair of ankle trauma, deformity, and/or treatment of degenerative ankle joints. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0008]    Embodiments and/or variations are now described by way of example with reference to the accompanying drawings. 
           [0009]      FIG. 1  illustrates a back view of an embodiment of a tibiotalar fusion system, including a curved fusion nail and delivery instrumentation, positioned within and around a human lower leg and foot, in accordance with principles of the present disclosure; 
           [0010]      FIG. 2  depicts a side view of an embodiment of a tibiotalar fusion system with the delivery instrumentation removed, in accordance with principles of the present disclosure; 
           [0011]      FIG. 3  illustrates a back view an embodiment of a tibiotalar fusion system with the delivery instrumentation removed, in accordance with principles of the present disclosure; 
           [0012]      FIG. 4  illustrates an embodiment of a tibiotalar fusion system including a curved fusion nail attached to a delivery drill guide jig instrument, in accordance with principles of the present disclosure; 
           [0013]      FIG. 5  depicts an embodiment of a tibiotalar fusion system including a curved fusion nail attached to a delivery drill guide jig instrument and fasteners passing through the curved tibiotalar fusion nail, wherein a distal portion of the curved fusion nail contains oval openings that allow for dynamic action of the curved tibiotalar fusion nail after placement in the bone, in accordance with principles of the present disclosure; 
           [0014]      FIG. 6  illustrates a side view of an embodiment of a tibiotalar fusion system including a curved fusion nail attached to a drill guide jig, in accordance with principles of the present disclosure; and 
           [0015]      FIG. 7  illustrates a side view of an embodiment of a tibiotalar fusion system including a curved fusion nail with fasteners passing through the various fastener passages and which is attached to a drill guide jig. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Described herein is a curved tibiotalar fusion system including a curved fusion nail and interlocking fasteners along with delivery and targeting instrumentation, and additionally, surgical methods for using a tibiotalar fusion system. The presently disclosed curved tibiotalar fusion system and surgical methods may be utilized for the fusion of degenerative joints, such as, for example, a tibiotalar joint fusion. Also disclosed are delivery and targeting instrumentations, such as, for example, a drill guide jig, to currently align the fasteners with the curved fusion nail after the curved fusion nail is placed in the desired bone tissue surrounding the targeted joint, such as, for example, a tibiotalar joint. 
         [0017]      FIG. 1  illustrates a preferred embodiment of a curved tibiotalar fusion system  10  including a rod, such as curved fusion nail  101 , placed distally within a tibia  103  and proximally within the talus bone  105  below the ankle (tibiotalar) joint  107 . Two fasteners  109  are located distally through the curved fusion nail  101  and the tibia bone  103 , and two fasteners  110  and  111  are located in the proximal end of the curved fusion nail  101  within the talus bone  105 . As shown in  FIG. 3 , in the preferred embodiment, one of the proximal fasteners  111  passes through the tibia bone  103 , across the ankle (tibiotalar) joint  107 , and into the talus bone  105  where it passes through and secures the curved fusion nail  101 . In an alternative embodiment, one of the proximal fasteners  110  may be inserted through the talus bone  105 , and secured into the fibula  301  for added construct strength. 
         [0018]    The curved fusion nail  101  includes a proximal end  113 , a distal end  115  and an elongate body  130  extending between the proximal end  113  and the distal end  115 . The elongate body  130  is curved in a manner allowing the curved fusion nail  101  to be inserted through the talus bone  105  and into the tibia bone  103  without penetrating the calcaneal bone  121 . In one embodiment, at least a portion of the elongate body  130  possesses a radius of curvature in a range between approximately (e.g., ±10%) 1.5 and 4.0 inches, or lesser or greater. For example, at least a portion of the elongate body  130  may possess a radius of curvature in a range between 2.0 and 3.0 inches. Additionally, the proximal end  113  and the distal end  115  of the nail  101  may be curved, as illustrated in the figures, and their respective radiuses of curvature may fall within the previously described ranges. In one embodiment, only the proximal end  113  is curved. The elongate body  130  is not limited to having a single radius of curvature. Different portions of the elongate body  130  may have different radiuses of curvature. For example, the radius of curvature of the middle portion of the elongate body  130  may be greater than the ends of the elongate body  130  such that the elongate body  130  becomes straighter near its ends. The elongate body  130  may have a circular cross section and have a diameter in a range between approximately (e.g., ±10%) 7.0 and 12.0 mm, for example, between 8.0 and 11.0 mm, and, for example, between 9.0 and 10.0 mm. The curved fusion nail  101  may be made of any suitable material for placement within the body, including, but not limited, titanium and/or stainless steel. The curved fusion nail  101  may also be coated with a therapeutic agent to aid in the healing process such as, for example, a bone-growth promoting agent. Each of the fasteners  109 ,  110 ,  111  may have an external thread, as shown in the figures, and have a diameter in a range between approximately (e.g., ±10%) 4.0 and 5.5 mm, for example, between 4.5 and 5.0 mm. 
         [0019]    In the preferred embodiment of the method disclosed the surgeon would drill a hole along a curved path through the talus bone  105  and the tibia bone  103 , then deliver a curved fusion nail  101  by entering the talus bone  105  at an angle deliver the curved fusion nail  101  through the talus bone  105 , across the ankle (tibiotalar) joint  107 , and then place the curved fusion nail  101  with its distal end  115  within the tibia bone  103 . This delivery method preserves the subtalar (talocalcaneal) joint  119  from fusion and maintains normal motion of the hindfoot. Once the curved fusion nail  101  is placed, a drill guide jig  123  is utilized with the curved fusion nail  101  that allows for the accurate placement  125  of the proximal fasteners  110  and  111 . The two distal fasteners  109  are then placed through the tibia bone  103  and the curved fusion nail  101 . 
         [0020]      FIG. 2  shows a side view of the delivered curved fusion nail  101 , and  FIG. 3  shows a back view of the delivered curved fusion nail  101 . In one embodiment the lower proximal fastener  110  might be placed through the talus bone  105 , and secured into the fibula  301  for added construct strength. 
         [0021]      FIG. 4  illustrates a curved fusion nail  101  with a fastener drill guide jig  123  attached to the proximal end  113  of the curved fusion nail  101 . The fastener drill guide jig  123  includes a base  140  that attaches to the proximal end  113  of the curved fusion nail  101 , and two stabilization arms  150   a,    150   b  that extend from the base  140 . Drill guide sleeves  160   a,    160   b  protrude from the respective free ends of the stabilization arms  150   a,    150   b  and may be pressed against the epidermis (not illustrated) covering the ankle. Each of the drill guide sleeves  160   a,    160   b  includes a central guide passage that permits one of the fasteners  110 ,  111  to be inserted therethrough, and which aligns the respective fastener with a targeted anatomical region. For example, the guide passage extending through the guide sleeve  160   a  may guide the fastener  111  along a path that allows the fastener  111  to be inserted through both the tibia bone  103  and the talus bone  105 . 
         [0022]    In one embodiment, as illustrated in  FIG. 5 , the hole  503  for the distal fastener  109  may be a non-circular shape such as, for example, an oval shape to allow for the dynamic compression of the fusion apparatus within the tibia bone  103  and the ankle joint by providing for movement of the curved fusion nail  101  over the distal fasteners  109 . In another embodiment the curved fusion nail  101 , the distal end  115  of curved fusion nail  101  may include two sets of holes  501  and  503 , with the holes  501  having, for example, a circular shape for static fastening, and the holes  503  having, for example, an oval shape for dynamic compression fastening, depending on the desire of the user. In one embodiment, the some or all of the holes  501 ,  503  may have an oval shape for dynamic compression fastening, and the holes for fasteners  110 ,  111  may each have a circular shape for static fastening. 
         [0023]      FIG. 6  shows a side view of the curved fusion nail  101  attached to a drill guide jig  123 .  FIG. 7  shows side view of the curved fusion nail  101  with fasteners passing through the various fastener passages. 
         [0024]    It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the described device as specifically shown here without departing from the spirit or scope of that broader disclosure. The various examples are, therefore, to be considered in all respects as illustrative and not limiting.