Abstract:
Systems and methods insert an expandable body in a collapsed configuration into a space defined between cortical bone surfaces. The space can, e.g., comprise a fracture or an intervertebral space. The systems and methods cause expansion of the expandable body within the space, thereby pushing apart the cortical bone surfaces to, e.g., reduce the fracture or push apart adjacent vertebral bodies as part of a therapeutic procedure.

Description:
RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 08/871,114, filed Jun. 9, 1997 and entitled “Systems and Methods for Treatment of Fractured or Diseased Bone Using Expandable Bodies,” which is a continuation-in-part of U.S. patent application Ser. No. 08/659,678, filed Jun. 5, 1996, which is a continuation-in-part of U.S. patent application Ser. No. 08/485,394, filed Jun. 7, 1995, which is a continuation-in-part of U.S. patent application Ser. No. 08/188,224, filed Jan. 26, 1994 entitled, “Improved Inflatable Device For Use In Surgical Protocol Relating To Fixation Of Bone.” 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to the treatment of bone conditions in humans and other animals.  
         BACKGROUND OF THE INVENTION  
         [0003]    There are 2 million fractures each year in the United States. There are also other bone diseases involving infected bone, poorly healing bone, or bone fractured by severe trauma. These conditions, if not successfully treated, can result in deformities, chronic complications, and an overall adverse impact upon the quality of life.  
         SUMMARY OF THE INVENTION  
         [0004]    The invention provides improved systems and methods for treating bone using one or more expandable bodies. The systems and methods insert an expandable body in a collapsed configuration into a space defined between cortical bone surfaces. The space can, e.g., comprise a fracture or an intervertebral space left after removal of the disk between two vertebral bodies. The systems and methods cause expansion of the expandable body within the space, thereby pushing apart the cortical bone surfaces. The expansion of the body serves, e.g., to reduce the fracture or to push apart adjacent vertebral bodies as part of a therapeutic procedure, so that healing can occur without deformity.  
           [0005]    Features and advantages of the inventions are set forth in the following Description and Drawings, as well as in the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a lateral view of a portion of a distal radius and humerus adjoining at the elbow in their normal anatomic condition;  
         [0007]    [0007]FIG. 2 is a lateral view of the distal radius and humerus shown in FIG. 1, except that the distal radius includes a fracture along which facing cortical bone surfaces have collapsed, creating a deformed condition;  
         [0008]    [0008]FIG. 3 shows a lateral view of the distal radius and humerus shown in FIG. 2, with an expandable body deployed in a collapsed geometry between the collapsed cortical bone surfaces;  
         [0009]    [0009]FIG. 4 is an enlarged view of the deployment of the expandable body deployed between the collapsed cortical bone surfaces as shown in FIG. 3;  
         [0010]    [0010]FIG. 5 shows a view of the distal radius and humerus shown in FIG. 3, with the expandable body expanded to exert pressure against the collapsed cortical bone surfaces, pushing them apart to restore a normal anatomic condition, so that the distal radius can heal without deformity;  
         [0011]    [0011]FIG. 6 is an enlarged view of the expanded body pushing the cortical bone surfaces apart, as shown in FIG. 5;  
         [0012]    [0012]FIG. 7 is a lateral view of two vertebral bodies and intervertebral disk in their normal anatomic condition;  
         [0013]    [0013]FIG. 8 is a view of the two vertebral bodies shown in FIG. 7, except that the intervertebral disk has been removed and the vertebral bodies have shifted out of normal orientation, creating a deformed condition;  
         [0014]    [0014]FIG. 9 shows a view of the vertebral bodies shown in FIG. 8, with an expandable body deployed in a collapsed geometry between the facing cortical bone surfaces between the vertebral bodies;  
         [0015]    [0015]FIG. 10 shows a view of the vertebral bodies shown in FIG. 9, with the expandable body expanded to exert pressure against the facing cortical bone surfaces, pushing the vertebral bodies apart to restore a normal anatomic condition, which can be healed without deformity; and  
         [0016]    [0016]FIG. 11 shows a view of the vertebral bodies shown in FIG. 9, with two expandable bodies deployed in the intervertebral space to exert pressure to push the vertebral bodies apart to promote healing without deformity.  
     
    
       [0017]    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.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    The use of expandable bodies to treat bones is disclosed in U.S. Pat. Nos. 4,969,888 and 5,108,404. The systems and methods disclosed in these patents treat bone from the inside out. That is, the systems and methods deploy an expandable body into the interior volume of the bone. Expansion of the body inside the bone compacts or compresses surrounding cancellous bone. The compaction of cancellous bone inside the bone exerts interior force upon outside cortical bone, making it possible to elevate or push broken and compressed cortical bone back to or near its original prefracture position.  
         [0019]    There are times, however, when fracture reduction is indicated by applying external pressure directly on cortical bone surfaces. FIGS. 1 and 2 exemplify one representative circumstance.  
         [0020]    [0020]FIG. 1 shows a normal human distal radius  10 , near the elbow joint  12 , where the radius  10  adjoins the humerus  14 . FIG. 2 shows a fracture  16  in the distal radius  10 . The fracture  16  can be caused by bone disease or trauma. As FIG. 2 shows, cortical bone surfaces  18  surrounding the fracture  16  have collapsed upon themselves, moving the radius  10  out of normal alignment with the humerus  14 . It is not desirable to allow the cortical bone surfaces  18  to heal or fuse in a collapsed condition, as deformity and discomfort can result.  
         [0021]    According to the invention (as FIGS. 3 and 4 show), an expandable body  20  is positioned in the fracture between the facing cortical bone surfaces  18 . FIGS. 3 and 4 show the expandable body  20  in a collapsed condition, which aids its deployment and placement in the fracture  16 .  
         [0022]    Access can be achieved either with a closed, mininimally invasive procedure or with an open procedure. FIG. 3 shows the expandable body  20  carried at the distal end of a catheter tube  22 . The catheter tube  22  is introduced through conventional percutaneous deployment through a guide tube or cannula  24 , under radiologic or CT monitoring.  
         [0023]    The materials for the catheter tube  22  are selected to facilitate advancement of the body  20  into position against the cortical bone surfaces  18  through the cannula  24 . The catheter tube  22  can be constructed, for example, using standard flexible, medical grade plastic materials, like vinyl, nylon, polyethylenes, ionomer, polyurethane, and polyethylene tetraphthalate (PET). The catheter tube  22  can also include more rigid materials to impart greater stiffness and thereby aid in its manipulation. More rigid materials that can be used for this purpose include Kevlar™ material, PEBAX™ material, stainless steel, nickel-titanium alloys (Nitinol™ material), and other metal alloys.  
         [0024]    The body  20  is caused to assume an expanded geometry within the fracture  16 , which is shown in FIGS. 5 and 6. To provide expansion of the body  20 , the catheter tube  22  includes an interior lumen  28 . The lumen  22  is coupled at the proximal end of the catheter tube  22  to a source of fluid  30 . The fluid  30  is preferably radio-opaque to facilitate visualization. For example, Renograff™ can be used for this purpose.  
         [0025]    The lumen  28  conveys the fluid  30  into the body  20 . As fluid  30  enters the body  20 , the body  20  expands, as FIGS. 5 and 6 show. Because the fluid  30  is radio-opaque, body expansion can be monitored fluoroscopically or under CT visualization. Using real time MRI, the body  20  may be filled with sterile water, saline solution, or sugar solution.  
         [0026]    Expansion of the body  20  exerts pressure directly against surrounding the cortical bone surfaces  18 . The pressure exerted by expanding body  20  moves surrounding the cortical bone surfaces  18  apart at the fracture  16 . The exerted pressure lifts surrounding cortical bone surfaces  18  at the fracture  16  (shown by arrow  26  in FIG. 6) out of the deformed, collapsed condition, back to or near the original prefracture position. The expandable body  20  thereby realigns the cortical bone surfaces  18  at the fracture  16  by the application of direct external pressure, e.g., to allow the bone to heal at or near its anatomic normal orientation by the application of conventional exterior casting or other conventional interior or exterior fixation devices.  
         [0027]    [0027]FIGS. 7 and 8 exemplify another circumstance where force applied by an expandable body directly against facing cortical bone surfaces may be indicated for therapeutic purposes. FIG. 7 shows two adjacent vertebral bodies  32  and  34 , separated by a healthy intervertebral disk  36  in a normally aligned condition. FIG. 8 shows the adjacent vertebral bodies  32  and  34  after disease or injury has necessitated the removal of the intervertebral disk  36 . The absence of the disk  36  in FIG. 8 has caused the vertebral bodies to shift out of normal alignment into a deformed orientation.  
         [0028]    As FIG. 9 shows, an expandable body  38  has been positioned between the vertebral bodies  32  and  34 , in the space  40  the disk  36  once occupied. FIG. 9 shows the deployment of the expandable body  38  at the distal end of a catheter tube  42 , through a cannula  44 , under radiologic or CT monitoring. As before stated, access can be achieved either with a closed, mininimally invasive procedure (as FIG. 9 contemplates) or with an open procedure.  
         [0029]    The catheter tube  42  includes an interior lumen  48 , which is coupled at the proximal end of the catheter tube  42  to a source of fluid  50  (which is preferably radio-opaque, such as Renograffin™). The lumen  48  conveys the fluid  50  into the body  38  to cause it to expand. As FIG. 10 shows, expansion of the body  38  exerts pressure directly against the facing cortical bone surfaces  52  of the two vertebral bodies  32  and  34 . The pressure exerted by the body  38  moves the cortical bone surfaces  52  apart about the intervertebral space  40 , as shown by arrows  46  in FIG. 10. The pressure exerted against the cortical bone surfaces  52  lifts the vertebral bodies  32  and  34  out of the deformed condition, back to or near their original position. The direct pressure exerted by the body  38  on the cortical bone surfaces  52  pushes the vertebral bodies  32  and  34  apart to allow placement of a disk prosthesis, or medication, or to allow fusion to occur without deformity by the application of conventional interior or exterior fixation devices.  
         [0030]    It should be appreciated that, in the embodiments shown, the use of more than one expandable body  20  or  38  may be indicated to move the targeted surfaces of cortical bone apart. For example, as FIG. 11 shows, a second expandable body  54  has been positioned in the space  40  with the first mentioned expandable body  38 . The second expandable body  54  can be carried by the same catheter tube  42  as the first expandable body  38 , or it can be carried by a separate catheter tube (not shown). A lumen  56  conveys the fluid  50  into the second expandable body  54 , causing it to expand, in the same way that the first expandable body  38  expands in the space  40 . As FIG. 11 shows, joint expansion of the bodies  38  and  54  in the space  40  exerts pressure against the facing cortical bone surfaces  52  of the two vertebral bodies  32  and  34 . The pressure exerted by the two bodies  38  and  54  moves the cortical bone surfaces  52  apart about the intervertebral space  40 , as shown by arrows  58  in FIG. 11. The pressure exerted by the two expandable bodies  38  and  54  lifts the vertebral bodies  32  and  34  out of the deformed condition, back to or near their original position, to allow placement of a disk prosthesis, or medication, or to allow fusion to occur without deformity by the application of conventional interior or exterior fixation devices.  
         [0031]    The material of the expandable body or bodies used can be selected according to the therapeutic objectives surrounding its use. For example, materials including vinyl, nylon, polyethylenes, ionomer, polyurethane, and polyethylene tetraphthalate (PET) can be used. The thickness of the body wall  58  is typically in the range of {fraction (2/1000)}ths to {fraction (25/1000)}ths of an inch, or other thicknesses that can withstand pressures of up to, for example, 250-500 psi.  
         [0032]    If desired, the material for the expandable body or bodies can be selected to exhibit generally elastic properties, like latex. Alternatively, the material can be selected to exhibit less elastic properties, like silicone. Using expandable bodies with generally elastic or generally semi-elastic properties, the physician monitors the expansion to assure that over-expansion and body failure do not occur. Furthermore, expandable bodies with generally elastic or generally semi-elastic properties may require some form of external or internal restraints. For example, the material for the body can be selected to exhibit more inelastic properties, to limit expansion of the wall  58  prior to wall failure. The body can also include one or more restraining materials, particularly when the body is itself made from more elastic materials. The restraints, made from flexible, inelastic high tensile strength materials, limit expansion of the body prior to failure.  
         [0033]    When relatively inelastic materials are used for the body, or when the body is otherwise externally restrained to limit its expansion prior to failure, a predetermined shape and size can be imparted to the body, when it is substantially expanded. The shape and size can be predetermined according to the shape and size of the surrounding cortical bone. The shape of the surrounding cortical bone and the presence of surrounding local anatomic structures are generally understood by medical professionals using textbooks of human skeletal anatomy, along with their knowledge of the site and its disease or injury. The physician is also able to select the materials and geometry desired for the body based upon prior analysis of the morphology of the targeted bone using, for example, plain films, spinous process percussion, or MRI or CRT scanning. The objective is to push cortical bone surfaces apart to meet the therapeutic objectives without harm. By definition, harm results when expansion of the body results in a worsening of the overall condition of the bone and surrounding anatomic structures, for example, by injury to surrounding tissue or causing a permanent adverse change in bone biomechanics.  
         [0034]    It should be appreciated that expandable bodies as described possess the important attribute of being able to push apart cortical bone in fractured or deformed bone structures, back to or near normal anatomic position. This attribute makes these expandable bodies well suited for the successful treatment of fractures or deformities in the spine, as well as throughout the appendicular skeleton, such as the distal radius, the proximal humerus, the tibial plateau, the femoral head, hip, and calcaneus.  
         [0035]    The features of the invention are set forth in the following claims.