Patent Document

RELATED APPLICATION  
       [0001]    This application claims the benefit of United States provisional application serial No. 60/243,194 filed Oct. 25, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to the treatment of bone conditions of the human and other animal body systems and, more particularly, to systems and methods for correcting such conditions.  
         BACKGROUND OF THE INVENTION  
         [0003]    Bone fractures, particularly osteoporotic bone fractures, are common in older adults. Due to the nature of osteoporotic bone, standard methods of fracture fixation yield unsatisfactory results. Such methods cannot adequately place the broken fragments back to their pre-fracture state. For instance, with a non-osteoporotic bone fracture, common practice includes inserting rods, pins and/or screws into the bone in order to reduce the fracture and/or fix the fracture fragments to plates. Osteoporotic bone generally cannot support such a method. Another common method for non-osteoporotic bone fractures involves maintaining the bone in a cast for several weeks. Osteoporotic bone that has suffered a crush fracture, such as a Colles&#39; fracture of the distal radius, will not heal properly if placed in a cast; the bone mechanics are altered such that the bone is shortened and/or subsides. Yet another non-osteoporotic fracture reduction method involves using an external fixation device. However, when used in elderly patients, the fixation pins may not remain within the weakened bone. Moreover, such a device typically increases the likelihood of infection at the treatment site. Further, because casts and/or an external fixation devices must be left in place for several weeks in order for the bone to heal, the lack of joint movement in the affected area often results in painful arthritis in the immobilized joints of the elderly patient.  
           [0004]    Even where osteoporosis is not present, it is typically necessary to immobilize a fractured bone to allow the bone to properly heal. This often requires immobilization of the joints adjacent to the fractured bone—often for extended periods of time. However, such immobilization often causes the joints to degenerate over time. Often, such treatment can result in temporary or permanent loss of joint motion. At the very least, such immobilization of the joints requires extensive and often painful rehabilitation for an individual to recover the full range of their joint motion.  
         SUMMARY OF THE INVENTION  
         [0005]    Because of the problems associated with treating distal radius fractures such as Colles&#39; fractures, and other bone fractures similar thereto, there is a need for a method and apparatus that will improve the existing protocol for treating such fractures such as reducing the pain resulting from the fracture fixation method used, reducing the chance that an infection will occur at the site, improving the likelihood that the fracture will heal properly and minimizing degeneration of the adjacent joints and allows for sooner resumption of activity. The present invention provides apparatus and a method of fracture reduction which satisfies this need.  
           [0006]    This invention provides a system that fixes or reduces osteoporotic and non-osteoporotic fractures in human and other animal body systems. Moreover, by immediately reducing and/or reinforcing the fractured bone, thereby rendering the bone capable of bearing limited loads, the present system promotes healing of the fractured bone while minimizing degeneration of the adjacent joints. It is particularly well suited for fractures of long bones such as the human distal radius.  
           [0007]    One aspect of the invention provides a tool for establishing a percutaneous path into bone. The tool is a cannula having a side wall defining an internal bore aligned along an axis. The cannula has a distal end. A circumferential opening is defined in the side wall. The circumferential opening has a distal terminus. The circumferential opening extends partially about the side wall and is elongated along the axis. The circumferential opening is adapted to accommodate passage of an expandable structure from within the bore. In one embodiment, the bore is solid between the distal terminus of the circumferential opening and the distal end of the cannula.  
           [0008]    In an alternate embodiment of the above described tool, the bore is open between the distal terminus of the circumferential opening and the distal end of the cannula. The cannula has a distal opening in the distal end communicating with the bore. The opening in the distal end can accommodate passage of a guide pin.  
           [0009]    In an alternate embodiment of the above described tool, the cannula desirably has a surface on its distal end to anchor the distal end in bone.  
           [0010]    Another aspect of the invention provides an assembly for treating bone, including a cannula as described above. The cannula has a distal opening in the distal end communicating with the bore. The opening in the distal end can accommodate passage of a guide pin. The assembly also includes an expandable structure. The expandable structure is adapted for insertion through bone into the cannula and expansion through the circumferential opening.  
           [0011]    Another aspect of the invention provides an assembly for treating bone, including a cannula as described above. Desirably, the bore is solid between the distal terminus of the circumferential opening and the distal end of the cannula. The assembly also includes an expandable structure. The expandable structure is adapted for insertion through bone into the cannula and expansion through the circumferential opening.  
           [0012]    Another aspect of the invention provides an assembly for treating bone, including a cannula as described above. Desirably, the cannula has a surface on its distal end to anchor the distal end in bone. The assembly also includes an expandable structure. The expandable structure is adapted for insertion through bone into the cannula and expansion through the circumferential opening.  
           [0013]    Another aspect of the invention provides an assembly as described above. Desirably, the expandable structure has radio opaque markers. The markers allow one to locate the expandable structure within a circumferential opening in a cannula.  
           [0014]    Another aspect of the invention provides a method for treating bone. The method includes providing a cannula and inserting the cannula into cancellous bone. The method also includes inserting an expandable structure through the cannula until the structure is in registration with a circumferential opening in the cannula. The method further includes expanding the expandable structure through the circumferential opening into contact with cancellous bone.  
           [0015]    Another aspect of the invention provides a method for treating bone, including a step of expanding an expandable structure. The expansion compacts cancellous bone.  
           [0016]    Another aspect of the invention provides a method for treating bone, including a step of compacting cancellous bone. The compaction of cancellous bone forms a cavity.  
           [0017]    Another aspect of the invention provides a method for treating bone, including a step of conveying a material into a cavity.  
           [0018]    Another aspect of the invention provides a method for treating bone, including a step of expanding an expandable structure such that the expansion moves fractured cortical bone. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is an anatomic view that shows bones of a human forearm;  
         [0020]    [0020]FIG. 2 is an anatomic view that shows bones of the forearm including an ulna and a fractured distal radius;  
         [0021]    [0021]FIG. 3 is an enlarged section view of the distal radius showing cancellous bone and cortical bone in a fractured condition;  
         [0022]    [0022]FIG. 4 is a plane view showing a kit containing a system of instruments used to treat bones and that embodies features of the invention;  
         [0023]    [0023]FIG. 5 is a perspective view of an obturator instrument that is contained in the kit shown in FIG. 4;  
         [0024]    [0024]FIG. 6 is a perspective view of a percutaneous cannula that is contained in the kit shown in FIG. 4;  
         [0025]    [0025]FIG. 7 is a perspective view of a drill bit instrument that is contained in the kit shown in FIG. 4;  
         [0026]    [0026]FIG. 8 is a perspective view of a fracture reduction cannula that is contained in the kit shown in FIG. 4, showing a distal end, a proximal end, and a circumferential opening;  
         [0027]    [0027]FIG. 8A is a perspective view of an alternate embodiment of a fracture reduction cannula constructed in accordance with the teachings of the present invention;  
         [0028]    [0028]FIG. 8B is a perspective view of another alternate embodiment of a fracture reduction cannula constructed in accordance with the teachings of the present invention;  
         [0029]    [0029]FIG. 9 is a side view of the fracture reduction cannula of FIG. 8 showing an end interior bore therethrough;  
         [0030]    [0030]FIG. 10 a  is an enlarged view of the distal end of the fracture reduction cannula, the distal end being solid;  
         [0031]    [0031]FIG. 10 b  is an enlarged view of the distal end of the fracture reduction cannula of FIG. 8, the distal end being open to accommodate passage of a guide pin;  
         [0032]    [0032]FIG. 11 is a perspective view of an instrument carrying an expandable structure, the instrument being contained in the kit shown in FIG. 4;  
         [0033]    [0033]FIG. 12 is an enlarged perspective view of an instrument, showing the expandable structure in an unexpanded state and, in broken lines, the expandable structure in an expanded state;  
         [0034]    [0034]FIG. 13 is a perspective view of a tamp that is contained in the kit shown in FIG. 4;  
         [0035]    [0035]FIG. 14 is a perspective view of a handle that is contained in the kit shown in FIG. 4; showing recesses therein;  
         [0036]    [0036]FIG. 15 is a perspective view showing the obturator instrument inserted into the handle, the handle being grasped by a hand;  
         [0037]    [0037]FIG. 15 a  is a side section view showing the obturator instrument inserted into the handle and advanced to the distal radius;  
         [0038]    [0038]FIG. 16 is a side section view showing the percutaneous cannula inserted over the obturator instrument and advanced to the distal radius;  
         [0039]    [0039]FIG. 17 is a side section view showing the drill bit instrument within the percutaneous cannula and advanced to the distal radius, and further showing the distal radius fracture and cancellous bone;  
         [0040]    [0040]FIG. 18 is a side section view showing the fracture reduction cannula within the percutaneous cannula and advanced into the cancellous bone of the distal radius, and further showing the circumferential opening facing the fracture;  
         [0041]    [0041]FIG. 19 is an enlarged view showing the fracture reduction cannula seated within cortical bone;  
         [0042]    [0042]FIG. 20 is an enlarged view showing the fracture reduction cannula seated within cortical bone and containing the unexpanded expandable structure;  
         [0043]    [0043]FIG. 21 is an enlarged view showing the fracture reduction cannula seated within cortical bone, containing the expanded expandable structure, and compressing cancellous bone and/or moving cortical bone;  
         [0044]    [0044]FIG. 21A is an enlarged view showing a fracture reduction cannula seated within cortical bone, with the expanded expandable structure compressing cancellous bone and/or moving cortical bone and creating a cavity which extends across a fracture line in the targeted bone;  
         [0045]    [0045]FIG. 22 is an enlarged view showing the fracture reduction cannula seated within cortical bone and containing the expanded expandable structure, showing compressed cancellous bone, displaced cortical bone, and a reduced fracture, and further showing a pin placed through the distal radius and into the ulna;  
         [0046]    [0046]FIG. 22A is an enlarged view showing a fracture reduction cannula seated within cortical bone and containing the expanded expandable structure, showing compressed cancellous bone, displaced cortical bone, a reduced fracture, and a cavity extending across a fracture line in the cortical bone, and further showing a pin placed through the distal radius and into the ulna;  
         [0047]    [0047]FIG. 23 is a top view showing a patient&#39;s forearm on a rolled towel, with horizontal finger traps on the patient&#39;s fingers, the instrument inserted through the handle and into the percutaneous cannula, with the fraction reduction cannula hidden from view, and the pin inserted into the patient&#39;s wrist;  
         [0048]    [0048]FIG. 24 is an enlarged view showing a cavity created by expansion of the expandable structure in the distal radius, the pin in place, the fracture reduction cannula, and the cavity ready to receive a bone filling material;  
         [0049]    [0049]FIG. 25 is an enlarged view showing the filling material beginning to fill the cavity;  
         [0050]    [0050]FIG. 26 is an enlarged view showing the tamp urging the filling material fully into the cavity;  
         [0051]    [0051]FIG. 27 is an enlarged view showing the filled cavity with the fracture reduction cannula and tamp removed; and  
         [0052]    [0052]FIG. 28 is an enlarged view showing an alternate embodiment of the fracture reduction cannula with a guide pin placed therethrough. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0053]    The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims.  
         [0054]    The preferred embodiment describes improved systems and methods that embody features of the invention in the context of treating bones. This is because the new systems and methods are advantageous when used for this purpose. However, aspects of the invention can be advantageously applied for diagnostic or therapeutic purposes in other areas of the body.  
         [0055]    The new systems and methods will be more specifically described in the context of the treatment of long bones such as the human distal radius. Of course, other human or animal bone types can be treated in the same or equivalent fashion.  
         [0056]    I. ANATOMY OF THE RADIUS  
         [0057]    The human forearm consists of two bones, the radius and the ulna. As shown in FIGS. 1 and 2, the radius  20  is a long bone that is situated on the thumb side of the forearm, while the ulna  26  is located at the little finger side. The radius  20  lies side by side with the ulna  26 , and it exceeds the ulna  26  both in length and in size.  
         [0058]    The upper, or proximal end  22  of the radius  20  is small and articulates with a part of the elbow joint, including the proximal ulna  28 . The distal end  24  of the radius  20  is large and articulates with two bones of the wrist, or carpus, known as the lunate  21  and scaphoid  27  bones. The inner, or medial side  25  of the distal radius  24  contains an ulnar notch  32  that articulates with the ulna  26 .  
         [0059]    II. BONE FRACTURES  
         [0060]    The systems and methods of the present invention are especially suited for treating fractures of long bones. One type of bone fracture that may be so treated is known as a Colles&#39; fracture or transverse wrist fracture. As shown in FIG. 2, such a fracture  34  generally occurs less than one inch from the distal end  24  of the radius  20 . Colles&#39; fractures are commonly noted in children and the elderly where the person tries to break or stop a fall by using his or her hands and arms. Colles&#39; fractures in children are often associated with sports such as skateboarding and in-line skating. In the elderly, Colles&#39; fractures are commonly caused by osteoporosis and/or in connection with a fall.  
         [0061]    Osteoporosis is a disease of the bone that is most commonly found in the middle-aged and elderly, particularly women. It is characterized by a gradual loss of a type of bone tissue known as cancellous bone  36 . As shown in FIG. 3, cancellous bone  36 , also referred to as trabecular bone, is a spongy bone tissue located within the harder outer or cortical bone. Cancellous bone  36  comprises most of the bone tissue of the extremities of long bones such as the radius  20 .  
         [0062]    In contrast to cancellous bone  36 , cortical bone  38  tissue is much harder and denser. Cortical bone  38  is layered over cancellous bone  36 , and provides a protective layer and support for long bones such as the radius  20 , as shown in FIGS. 1 and 2. At the ends of such bones, however, the cortical bone  38  layer becomes thinner. Where osteoporosis has significantly weakened the cancellous bone  36 , such regions at the ends of long bones become especially prone to fracture and/or collapse.  
         [0063]    It may be indicated, due to disease or trauma, to reduce fractured cortical bone  38  and/or compress cancellous bone  36  within long bones such as the radius  20 . The compression, for example, can be used to form an interior cavity  35 , which receives a filling material  99 , e.g., a flowable material that sets to a hardened condition, such as poly(methylmethacrylate), as well as a medication, or combinations thereof, to provide improved interior support for cortical bone  38  or other therapeutic functions, or both. The compaction of cancellous bone  36  also exerts interior force upon cortical bone  38 , making it possible to elevate or push broken and compressed bone back to or near its original pre-fracture, or other desired, condition.  
         [0064]    III. THE INSTRUMENTS  
         [0065]    [0065]FIG. 4 shows instruments, arranged as a kit  200 , which are usable in association with each other to reduce fractured bone. The number and type of instruments can vary. FIG. 4 shows seven representative instruments, each having a different size and function.  
         [0066]    In FIG. 4, the kit  200  includes an obturator instrument  12  for penetrating soft tissue and bone; a percutaneous cannula  14  that functions as a guide sheath; a drill bit instrument  16  that is used for drilling into bone; a fracture reduction cannula  18  used in reducing fractures and that is inserted into bone and designed to receive an expandable structure; a bone compaction instrument  80  that functions to deliver a filling material  99  into a cavity  35  in bone and that carries an expandable structure  86  that may be expanded in bone; a tamp  81  functions to urge residual bone filling material into bone; and a handle  13  with recesses that receives instruments  12 ,  14 ,  16  and  18 .  
         [0067]    Instruments  12 ,  14 ,  16 , and  18  share some common features, although they are intended, in use, to perform different functions. Instruments  12 ,  14 ,  16 , and  18  each comprise an elongated, cylindrical body  40  having a proximal end  42  and a distal end  44 . Instruments  12 ,  14 ,  16 , and  18  are each made of a rigid, surgical grade plastic or metal material.  
         [0068]    A. The Obturator Instrument  
         [0069]    The first instrument  12  functions as an obturator. As shown in FIG. 5, its distal end  44  is tapered to present a penetrating surface  50 . In use, the surface  50  is intended to penetrate soft tissue and/or bone in response to pushing or twisting forces applied by the physician at the proximal end  42 . In a preferred embodiment, the proximal end  42  of the obturator instrument  12  mates with a handle  13 , to be described in detail later.  
         [0070]    The proximal end  42  of the obturator instrument  12  presents a flanged surface  52 . The flanged surface  52  is designed to fit securely into a recess in the handle  13 , such that pushing or twisting forces applied to the proximal end  42  of the obturator  12  instrument will not displace the obturator instrument  12 . The flanged surface  52  tapers from a larger outer diameter to a smaller outer diameter in the direction of the proximal end  42 . The flanged surface  52  includes an array of circumferentially spaced teeth  54  with intermediate flutes  56 .  
         [0071]    An interior bore  60  extends through the obturator instrument  12  from the distal end  44  to the proximal end  42 . Desirably, the interior bore  60  is sized to accommodate a conventional surgical guide pin  108  component to aid in its deployment, as will be described in greater detail later.  
         [0072]    The obturator instrument  12  has an outer surface  142  that is sized such that one may slide a percutaneous cannula  14  over the obturator instrument  12  as described below.  
         [0073]    B. The Percutaneous Cannula  
         [0074]    The second instrument  14  functions as a percutaneous cannula or guide sheath. It also serves to protect soft tissue and nerves, ligaments, muscle and vasculature from the use of a drill bit instrument  16 , which will be described in greater detail later.  
         [0075]    As shown in FIG. 6, the percutaneous cannula  14  is somewhat larger in diameter than, and is not as long as, the obturator instrument  12 . In one embodiment, the cannula  14  is approximately 2 inches long, although it could be various other lengths, depending upon the thickness of the patient&#39;s soft tissue at the surgical site. Desirably, the percutaneous cannula  14  is made of metal, and contains markings  120  along its outer surface  142  to indicate the depth at which it is placed into a patient&#39;s distal radius  24 .  
         [0076]    The proximal end  42  of the percutaneous cannula  14  presents a tapered flange  52 , as FIG. 6 shows. The flanged surface  52  is designed to fit securely into a recess in the handle  13 , such that forces applied to the proximal end  42  of the percutaneous cannula  14  will not displace the percutaneous cannula  14 . The tapered flange  52  changes from a larger diameter to a smaller diameter in the direction of the proximal end  42 . The tapered flange  52  of the percutaneous cannula  14  also includes an array of circumferentially spaced teeth  54  with intermediate flutes  56 . The form and orientation of the teeth  54  and flutes  56  on the percutaneous cannula  14  correspond to the form and orientation of teeth  54  and flutes  56  on the fracture reduction cannula  18 .  
         [0077]    As shown in FIG. 6, the percutaneous cannula  14  includes an interior bore  60  that extends from its distal end  44  to its proximal end  42 . Desirably, the interior bore  60  is sized to accept the obturator instrument  12 . The size of the interior bore  60  permits a physician to slide and rotate the percutaneous cannula  14  relative to the obturator instrument  12 , and vice versa, as will be described in greater detail later.  
         [0078]    The distal end  44  of the percutaneous cannula  14  presents an end surface  62 . Desirably, the surface of the distal end  44  is designed to penetrate soft tissue. In use, the end surface  62  of the percutaneous cannula  14  is intended to penetrate soft tissue surrounding the obturator instrument  12 , in response to pushing or twisting forces applied at the proximal end  42 . If desired, the end surface  62  can incorporate one or more teeth (not shown) which anchor the cannula  14  to the surface of the targeted bone.  
         [0079]    C. The Drill Bit Instrument  
         [0080]    The third instrument functions as a drill bit. As shown in FIG. 7, The drill bit instrument  16  has generally the same physical dimensions as the obturator instrument  12 . Like the obturator instrument  12 , the drill bit instrument  16  is intended, in use, to fit for sliding and rotational movement within the interior bore  60  of the percutaneous cannula  14 .  
         [0081]    The distal end  44  of the drill bit instrument  16  includes machined cutting edges  64 , as shown in FIG. 7. In use, the cutting edges  64  are intended to penetrate hard tissue in response to rotation and longitudinal load forces applied at the proximal end  42  of the drill bit instrument  16 .  
         [0082]    As further shown in FIG. 7, the proximal end  42  presents a tapered flange  52 , substantially identical to the flange  52  on the obturator instrument  12 , as FIG. 5 shows. The flanged surface  52  is designed to fit securely into a recess in the handle  13 , such that forces applied to the proximal end  42  of the drill bit instrument  14  will not displace the drill bit instrument  14 . Like the obturator instrument  12 , the tapered flange  52  changes from a larger diameter to a smaller diameter in the direction of the proximal end  42 . The tapered flange  52  of the drill bit instrument  16  also includes an array of circumferentially spaced teeth  54  with intermediate flutes  56 . The form and orientation of the teeth  54  and flutes  56  on the drill bit instrument  16  correspond to the form and orientation of the teeth  54  and flutes  56  on the obturator instrument  12 .  
         [0083]    D. The Fracture Reduction Cannula  
         [0084]    The fourth instrument functions as a fracture reduction cannula  18 . As shown in FIG. 8, the fracture reduction cannula  18  is somewhat smaller in diameter than, and is longer than, the percutaneous cannula  14 . In one embodiment, the fracture reduction cannula  18  is approximately 3½ inches in length, although it could be various other lengths depending on the size of the patient and the desired location within the targeted bone. Like both the obturator instrument  12  and the drill bit instrument  16 , the fracture reduction cannula  18  is intended, in use, to fit for sliding and rotational movement within the interior bore  60  of the percutaneous cannula  14 .  
         [0085]    The proximal end  42  of the fracture reduction cannula  18  presents a flanged surface  52 . The flanged surface  52  is designed to fit securely into a recess in the handle  13 , such that pushing or twisting forces applied to the proximal end  42  of the obturator  12  instrument will not displace the fracture reduction cannula  18 . Like the percutaneous cannula  14 , the flanged surface  52  of the fracture reduction cannula  18  tapers from a larger outer diameter to a smaller outer diameter in the direction of the proximal end  42 . The flanged surface  52  includes an array of circumferentially spaced teeth  54  with intermediate flutes  56 .  
         [0086]    The fracture reduction cannula  18  is sized to fit within the interior bore  60  of the percutaneous cannula  14 . The size of the interior bore  60  permits a physician to slide and rotate the fraction reduction cannula relative to percutaneous cannula  14 , and vice versa, as will be described in greater detail later.  
         [0087]    As further shown in FIG. 8, the fracture reduction cannula  18  includes a side wall  66  that defines an interior bore  68  that extends from the distal end  44  of the fracture reduction cannula  18  to its proximal end  42 . The interior bore  68  is adapted to allow passage of, among other things, an expandable structure  86 . In a preferred embodiment, the distal end  44  of the interior bore  68  is solid, as shown in FIG. 10 a.  In an alternate embodiment, the distal end  44  of the bore  68  is not solid, but rather, it is open to accommodate passage of an instrument such as a guide pin  108 , as shown in FIG. 10 b.  As another alternative, the distal end of the bore  68  could be hollow, such that a portion of the expandable structure could extend into the distal end  44  of the cannula  18 .  
         [0088]    The fracture reduction cannula  18  further includes a circumferential opening  70  in the side wall  66 . In one embodiment, the circumferential opening  70  extends approximately one-half inch in length along its longitudinal axis, although the size of this opening could vary depending upon the dimensions of the targeted bone and the size of the expandable structure. The circumferential opening  70  is sized to accommodate an expandable structure  86 . The circumferential opening  70  desirably also allows a filling material  99  to be placed near and/or into the fracture site.  
         [0089]    [0089]FIG. 8A depicts one alternate embodiment of a fracture reduction cannula  18 A constructed in accordance with the teachings of the present invention. Because many of the disclosed components are similar to those previously described, like reference numerals will be used to denote similar components. In this embodiment, the distal end  44 A of the cannula  18 A is not solid, but rather extends along the side wall  66 A, with one or more longitudinally extending teeth  120  disposed at the distal end  44 A.  
         [0090]    E. The Handle  
         [0091]    The handle  13 , which can be made from a molded or cast rigid plastic or metal material, is more fully described in U.S. application Ser. No. 09/014,229, filed on Jan. 27, 1998, the disclosure of which is incorporated herein by reference. As shown in FIG. 14, the handle has a smooth upper side  17 . Its lower side  29  contains recesses  15  and  19 . The flanged surfaces of the obturator instrument  12 , the drill bit instrument  16 , the percutaneous cannula  14 , and the fracture reduction cannula  18  mate with the handle  13 . Recess  15  is adapted to accept the obturator  12  and the drill bit instrument  16  while recess  19  is adapted to accept the fracture reduction cannula  18 . If desired, another recess can be provided (not shown) sized to accept the percutaneous cannula  14  in a similar manner.  
         [0092]    F. The Bone Compaction and/or Displacement Instrument  
         [0093]    [0093]FIG. 11 shows an instrument  80  for accessing bone for the purpose of compacting cancellous bone  36  and/or displacing cortical bone  38 . The instrument  80 , and instructions for assembling same, are more fully set out in U.S. application Ser. No. 09/420,529, filed on Oct. 19, 1999, incorporated herein by reference.  
         [0094]    The instrument  80  includes a catheter tube assembly  82 , as shown in FIG. 11. The distal end  84  of the catheter tube assembly  82  carries an expandable structure  86 . In use, the expandable structure  86  is deployed and expanded inside bone, e.g., in the radius  20  as shown in FIGS. 20, 21, and  22 , to compact cancellous bone  36  and/or displace cortical bone  38 , as will be described later.  
         [0095]    As further shown in FIG. 11, the instrument  80  includes an outer catheter body  88 , and an inner catheter body  90  which extends through the outer catheter body  88 . The proximal ends  92  of the outer  88  and inner  90  catheter bodies are coupled to a y-shaped adaptor/handle  94 . The y-shaped adaptor/handle  94  carries a first port  96  and a second port  98  at its proximal end  92 . The first port  96  is adapted to be coupled with an inflation syringe  101 , the syringe  101  in the present case being used to deliver a pressurized liquid into the expandable structure  86 . The second port  98  is adapted for insertion of a stiffening stylet (not shown) to facilitate insertion of the distal end  84  of the instrument  80 .  
         [0096]    As FIG. 11 shows, the expandable structure  86  is coupled at its proximal end  95  to the distal end  93  of the outer catheter body  88 . Likewise, the expandable structure  86  is coupled at its distal end  87  to the distal end  84  of the inner catheter body  90 .  
         [0097]    The outer catheter body  88  defines an interior bore, through which the inner catheter body  90  extends. The interior bore, in use, conveys a pressurized liquid, e.g., a radio-opaque solution such as CONRAY® solution, or another fluid into the expandable structure  86  to expand it.  
         [0098]    The material from which the expandable structure  86  is made should possess various physical and mechanical properties to optimize its functional capabilities to compact cancellous bone  36 , and to move cortical bone  38 . Desirably, the expandable structure  86  has the capability to move cortical bone  38  from a fractured condition to a pre-fractured or other desired condition, or both. The three most important properties of expandable structure  86  are the ability to expand its volume; the ability to deform in a desired way when expanding and assume a desired shape inside bone; and the ability to withstand abrasion, tearing, and puncture when in contact with cancellous bone  36 .  
         [0099]    The desired properties for the structure material, and the description for creating a pre-formed structure, are more fully set out in U.S. application Ser. No. 09/420,529, filed on Oct. 19, 1999.  
         [0100]    As shown in FIG. 11, the expandable structure  86  carries radio-opaque markers  91  located at a distal end  102  and at a proximal end  104  of segmented shaped regions  100  of the expandable structure  86 . The radio opaque markers  91  function to indicate, under fluoroscopic or other real-time monitoring, the location of the segmented shaped regions  100  in relation to the circumferential opening  70  of the fracture reduction cannula  18 .  
         [0101]    [0101]FIG. 12 illustrates the expandable structure in a collapsed state (solid lines) and an expanded state (broken lines).  
         [0102]    G. The Pin  
         [0103]    One or more conventional smooth Steinman pins  130  or Kirschner (“K”) wires may be provided to assist in aligning and/or stabilizing fracture fragments, as will be described in greater detail later.  
         [0104]    H. The Filling Material Instruments  
         [0105]    The filling material  99  instruments include a tamp  81  as shown in FIG. 13, and a standard syringe. The filling material  99  is introduced through the syringe and into the fracture reduction cannula  18 . Residual filling material  99  may be urged through the fracture reduction cannula  18  by employing the tamp  81 , as will be described in greater detail later.  
         [0106]    I. The Kit  
         [0107]    As shown in FIG. 4, a kit  200  is provided, including instruments  12 ,  13 ,  14 ,  16 ,  18 ,  80 , and  81 . The kit  200  and the instruments contained therein are sterile and are sealed until an instance of use.  
         [0108]    IV. ILLUSTRATIVE USE OF THE SYSTEM  
         [0109]    The size and shape of the access tools and/or expandable structure(s)  86  to be used, and the amount of bone to be moved, are desirably selected by the physician, taking into account the morphology and geometry of the site to be treated. The shape of the joint, the bones and soft tissues involved, and the local structures that could be harmed if moved inappropriately, are generally understood by medical professionals using textbooks of human anatomy along with their knowledge of the site and its disease and/or injury. The physician is also desirably able to select the desired shape and size of the expandable structure  86 , the cavity  35  and their placement based upon prior analysis of the morphology of the targeted bone and joint using, for example, plain film x-ray, fluoroscopic x-ray, or MRI or CT scanning. The shape, size and placement are desirably selected to optimize the strength and ultimate bonding of the fracture relative to the surrounding bone and/or tissue of the joint.  
         [0110]    In a typical procedure, a patient is placed under local anesthesia, although general anesthesia may instead be employed. Where a fracture  34  is that of a distal radius  24 , a physician makes an incision of approximately one (1) centimeter on the radial aspect of the distal radius  24 . In an alternate embodiment, one may access the distal radius  24  by an approach through the ulna  26 . The distance between the incision and the fracture  34  is approximately 0.5 centimeter. Of course, while the present procedure is described in the context of a minimally invasive surgery, various other surgical approaches, including percutaneous, subcutaneous, non-open, partially open and/or completely open surgical approaches may be utilized in accordance with the teachings of the present invention.  
         [0111]    After making the incision, the physician spreads the soft tissue by using a small clamp designed to avoid injury to nearby nerves, muscles, and vasculature. The physician then acquires the obturator instrument  12  and the handle  13 . The obturator instrument  12  may have at its proximal end  42  a flanged surface  52  that mates with a recess  15  within the handle  13 . Use of the handle  13  with the obturator instrument  12  will produce axial as well as radial movement, as shown in U.S. application Ser. No. 09/014,229, filed on Jan. 27, 1998. The physician then fits the proximal end  42  of the obturator instrument  12  into recess  15  in the handle  13 , as shown in FIG. 15.  
         [0112]    The physician next twists the handle  13  while applying longitudinal force to the handle  13 . In response, the tapered surface of the obturator instrument  12  rotates and penetrates soft tissue through the incision, as shown in FIG. 15 a.  The physician may also tap the handle  13 , or otherwise apply appropriate additional longitudinal force to the handle  13 , to advance the obturator instrument  12  through soft tissue.  
         [0113]    Under fluoroscopic monitoring or other real-time monitoring, the physician advances the obturator instrument  12  through soft tissue down to the distal radius  24 , as FIG. 15 a  shows. The obturator instrument  12  is inserted distal to proximal from the radial side of the radius  20  to the ulnar side of the radius  20 . The obturator instrument  12  is introduced into the radius  20 . Desirably, the obturator instrument  12  is introduced at an angle between minus 10 degrees and 45 degrees to the radio-carpal joint. More desirably, the obturator instrument  12  is introduced at an angle between zero degrees and 30 degrees to the radio-carpal joint. Most desirably, the obturator instrument  12  is introduced at an angle equal to the angle of the radiocarpal joint, i.e., approximately 23 degrees. Of course, if desired, the physician may utilize various other approach paths to access the bone, including a dorsal approach.  
         [0114]    The physician next removes the handle  13  from the obturator instrument  12  and places the proximal end  42  of the percutaneous cannula  14  in a recess  19  in the handle  13 . The physician slides the percutaneous cannula  14  over the obturator instrument  12 , distal end  44  first. The physician then twists the handle  13  while applying longitudinal force to the handle  13 , in order to seat the percutaneous cannula  14  against and/or into the external cortical bone  38 , as shown in FIG. 16. Once the percutaneous cannula  14  is seated in the cortical bone  38 , the obturator instrument  12  is removed, proximal end  42  first.  
         [0115]    In an alternate embodiment, instead of using the obturator instrument  12  to access external cortical bone  38 , the physician may instead insert a conventional spinal needle, the needle having an outer sheath and a stylus, into the bone. Upon puncturing the bone, the physician removes the stylus and inserts a guide pin  108  through the outer sheath. The sheath is then removed and the fracture reduction cannula  18  is deployed over the guide pin  108 . The physician then fits the proximal end  42  of the percutaneous cannula  14  into a recess  19  in the handle  13  and slides the assembly, distal end  44  first, over the fracture reduction cannula  18 , as shown in FIG. 28. Subsequently, the guide pin  108  is removed, proximal end first.  
         [0116]    After removing the obturator instrument  12 , or the guide pin  108  as in the case of the alternate embodiment described above, the handle  13  is removed from the percutaneous cannula  14 . As shown in FIG. 15, the proximal end  42  of a drill bit instrument  16  is then placed in a recess in the handle  13 . The preferred size of the drill bit  16  is 3.2 millimeters. The physician slides the drill bit assembly distal end  44  first through the bore  60  of the percutaneous cannula  14 . Using manual pressure, the drill bit instrument  16  is advanced down to and into the distal radius  24 . As an alternate embodiment, instead of using manual pressure, the physician could connect the proximal end  42  of the drill bit instrument  16  to a conventional motor-driven drill. The physician directs the drill bit instrument  16  to penetrate the cortical bone  38  and the cancellous bone  36  of the distal radius  24 , as shown in FIG. 17.  
         [0117]    After drilling through cortical bone  38  and into cancellous bone  36 , the physician removes the drill bit instrument  16  from the handle  13 . The fracture reduction cannula  18  is then inserted, distal end  44  first, into the bore of the percutaneous cannula  14 , as shown in FIG. 18. The distal end  44  of the fracture reduction cannula  18  extends beyond the distal end  44  of the percutaneous cannula  14 . In an alternate embodiment, the physician may at this point remove the percutaneous cannula  14 , leaving only the fracture reduction cannula  18  in place. In one embodiment, it is preferred to employ a fracture reduction cannula  18  that has screw threads  71  on its distal end  44  as shown in FIG. 9, thereby enabling the fracture reduction cannula  18  to be anchored to an interior surface of cortical bone  38  in response to rotation of the fracture reduction cannula  18 , e.g., by using the handle  13 . In an alternative embodiment (see FIG. 8B), the physician may employ a fracture reduction cannula  18  that has a blunt, tapered distal end  44  instead of screw threads  71  on the distal end  44 . If such a fracture reduction cannula  18  is employed, the physician may choose to drill a hole in cortical bone  38  in which to seat the blunt, tapered distal end  44 . Desirably, if the distal end  44  is blunt and tapered, the fracture reduction cannula  18  may be adapted to rotate independently from the distal end  44 . As another alternative, a cannula  18 A as depicted in FIG. 8A could be inserted into the targeted bone as previously described, with the teeth  120  anchoring the distal end  44 A of the cannula  18 A to the cortical wall (not shown) of the targeted bone region. With this embodiment, it would not be necessary to drill a hole through the cortical wall to anchor the distal end  44   a  of the cannula  18 A.  
         [0118]    In another embodiment, the access path can be made directly through the one or more fracture lines in the targeted bone. Such an arrangement minimizes trauma to the fractured bone (by reducing additional damage to healthier sections of the bone) and permits the creation of a cavity  35  which extends to each side of the fracture line.  
         [0119]    The fracture reduction cannula  18  is placed into the cancellous bone  36  of the distal radius  24  such that the circumferential opening  70  is facing towards the fracture, as shown in FIG. 18. The fracture reduction cannula  18  is checked radiologically to ensure that the circumferential opening  70  is contained entirely within the cancellous bone  38  of the radius  20 . In one embodiment, one or more markings (not shown) can be provided on the proximal end  42  of the cannula  18 , allowing the physician to visually gauge the orientation of the cannula  18 . In one embodiment, the fracture reduction cannula  18  is approximately 3 to 4 inches in length.  
         [0120]    The physician can now acquire the catheter tube assembly  82  for placement into the bore  68  of the fracture reduction cannula  18 . In one embodiment, the uninflated expandable structure  86  carried by the catheter tube measures 12 millimeters in length from its proximal end to its distal end, although structures  86  of varying lengths could be used, including expandable structures  86  of 15 mm or 20 mm, depending upon the size of the patient, the size and location of the fracture  34 , the size of the opening  70  and the cavity  35  size and shape and/or displacement of bone desired. The catheter tube assembly  82  is now introduced into the bore  68  of the fracture reduction cannula  18 .  
         [0121]    The physician guides the catheter tube assembly  82  through the fracture reduction cannula  18  until the expandable structure  86  enters and lies adjacent to the circumferential opening  70  of the fracture reduction cannula  18 , as shown in FIG. 20. In one embodiment, the distal end  44  of the fracture reduction cannula  18  is solid, as shown in FIG. 9, thus preventing an expandable structure  86  from emerging from the distal end  44  of the fracture reduction cannula  18 . The placement of the expandable structure  86  within the circumferential opening  70  can be determined by radio opaque markers  91  located on the expandable structure  86 , as shown in FIG. 11. The expandable structure  86  is passed into bone through the fracture reduction cannula  18  in a normally collapsed and non-inflated condition. The expandable structure  86  is now aligned with cancellous bone  36 .  
         [0122]    The physician, after verifying that the expandable structure  86  is adjacent the circumferential opening  70 , conveys a pressurized fluid, such as a radio opaque fluid, through the catheter tube assembly  82  and into the expandable structure  86 . The expandable structure  86  now expands into cancellous bone  36 , as shown in FIG. 21. The fracture reduction cannula  18  desirably directs the expanding structure  86  towards the fracture  34 . Progress of the expandable structure  86  is evaluated both on A-P, or anterior-posterior, and lateral x-rays. Preferably, the A-P x-ray is used until the distal end  24  of the radius  20  begins to move, at which point both A-P and lateral views are obtained. The pressurized fluid is used to inflate the expandable structure  86  and expand it through the circumferential opening  70  in order to compress cancellous bone  36  and/or displace cortical bone  38 . The expandable structure  86  will desirably form an interior cavity  35  in the cancellous bone  36 , as shown in FIG. 24. Desirably, the compressed cancellous bone  36  will seal any fractures  34  and/or cracks in the targeted bone through which the filling material  99 , to be described later, can flow out of the targeted treatment area.  
         [0123]    The compression of cancellous bone  36 , as shown in FIG. 22, can also exert an interior force upon the surrounding cortical bone  38 . The interior force will elevate or push broken and compressed bone back to or near its original prefracture, or other desired, condition. Once the fracture  34  is well aligned, it is preferred to introduce one or more smooth “Steinman” pins  130  or K-wires proximal to the joint surface of the radius  20  and distal to the inflated expandable structure  86 . The pins  130  can be placed across the distal end  24  of the radius  20  and into the distal ulna  30 , as shown in FIGS. 22 and 24- 27 . Alternatively, the pin(s)  130  can be secured into the radius  20  without penetrating the ulna  26 . The pin  130  desirably prevents the fracture  34  from displacing upon further manipulation of the wrist and/or contraction of the expandable structure  86 . If desired, additional pins  130  can be used to manipulate and/or secure other cortical bone fragments, or can be used to further secure a single bone fragment.  
         [0124]    In one or more alternate embodiments, the pins  130  can be introduced once a bone fragment has been displaced to a prior position, but prior to completion of the inflation steps. For example, where inflation of the balloon displaces a fragment to a desired position, but addition cavity creation is desired, the fragment may be secured in position using one or more pins  130 , and then the balloon can be further inflated to create a larger cavity  35  and/or compress additional cancellous bone  36 .  
         [0125]    As shown in FIG. 23, in one preferred embodiment, the patient&#39;s fingers of the affected arm can be placed in horizontal finger traps  132 , with the patient&#39;s palm facing the treatment table. A rolled towel  133  may be placed under the patient&#39;s wrist. By grasping the finger traps  132  and gently pulling on them, the physician can extend the patient&#39;s arm and thus reduce any pressure that may be exerted at the fracture site. This approach potentially allows for an improved correction of the volar tilt (15 degrees) of the distal radius  24 . If desired, this can be accomplished prior to, during or after fracture reduction has been accomplished.  
         [0126]    Once the interior cavity  35  is formed and any desired pins  130  set in place, the expandable structure  86  is collapsed and the catheter tube assembly  82 , with the collapsed expandable structure  86 , is removed,. As shown in FIG. 27, the cavity  35  is now in a condition to receive a filling material  99  through the fracture reduction cannula  18 . The filling material  99  can be any of a number of available bone filling materials, which include, but are not limited to, resorbable and/or remodelable bone cements, calcium phosphates, allograft tissue, autograft tissue, poly(methylmethacrylate) or Norian SRS® bone matrix. The filling material may be introduced into the fracture reduction cannula by means of a syringe (not shown). The filling material  99  progresses through the fracture reduction cannula  18  and into the circumferential opening  70  of the fracture reduction cannula  18 . The filling material  99  desirably provides improved interior structural support for cortical bone  38 . Desirably, the filling material  99  extends proximal to any cortical defects created by the drill bit instrument  16  and by the fracture reduction cannula  18 . In one embodiment, approximately two (2) to seven (7) cubic centimeters of filling material  99  can be injected into the cavity  35 .  
         [0127]    After the filling material  99  is introduced, a tamp  81  may be inserted into the fracture reduction cannula  18  as shown in FIG. 26, for the purpose of urging residual filling material  99  into the interior cavity  35 . Tamping of the filling material  99  may also cause the material to interdigitate into the surrounding cancellous bone  36 , further supporting the cancellous  36  and cortical bone  38 . The fracture reduction cannula  18  and (if still present) the percutaneous cannula  14  are removed. If desired, any void remaining subsequent to removal of the cannula  18  can be filled with filling material  99 . The patient should be kept immobile for ten to fifteen minutes. After the immobilization, the pin(s)  130  and finger traps  132  can be removed and the hand of the patient is checked for motion. The entry site is covered with appropriate antibiotics and an adhesive strip is applied.  
         [0128]    [0128]FIGS. 21A and 22A depict an alternate embodiment in which the expandable structure  86  is expanded within the fractured bone to create a cavity  35  which extends across at least one fracture line in the bone. In this embodiment, the filling material  99  ultimately introduced into the cavity  35  can extend across the fracture line and desirably interdigitate into the cancellous bone of the fragmented section(s). This will desirably anchor the fractured sections to the bone, thereby permitting the bone to undergo significant distractive and/or torsional loading without slippage along the fracture line(s) and/or subsequent refracture of the treated bone.  
         [0129]    If desired, the disclosed systems and methods could be used with equal utility in reducing and/or reinforcing fractures in bones of younger individuals and/or individuals not having osteoporosis. In such patients, the present systems and methods would allow for an immediate resumption of activity, reducing the opportunity for degradation of adjacent joints and promoting healing of the fracture.  
         [0130]    The features of the invention are set forth in the following claims.

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