Abstract:
The invention provides a method of correcting numerous bone abnormalities including bone tumors and cysts, avascular necrosis of the femoral head, tibial plateau fractures and compression fractures of the spine. The abnormality may be corrected by first accessing and boring into the damaged tissue or bone and reaming out the damaged and/or diseased area using any of the presently accepted procedures or the damaged area may be prepared by expanding a bag within the damaged bone to compact cancellous bone. After removal and/or compaction of the damaged tissue the bone must be stabilized.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. patent application Ser. No. 09/909,667, filed Jul. 20, 2001, which claims priority to U.S. Provisional Application No. 60/219,853 filed Jul. 21, 2000, the entirety of which is incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to methods and devices for correcting bone abnormalities and involves the use of a surgical mesh bag which is inserted into a prepared cavity in bone. The bag is inflated using bone replacement material to expand and fill the cavity.  
           [0003]    U.S. Pat. Nos. 5,549,679 and 5,571,189 to Kuslich, describe a device and method for stabilizing the spinal segment with an expandable, porous fabric implant for insertion into the interior of a reamed out disc which is packed with material to facilitate bony fusion. In the present invention, a similar bag is used to correct bone abnormalities including, but not limited to, bone tumors and cysts, tibial plateau fractures, avascular necrosis of the femoral head and compression fractures of the spine.  
           [0004]    U.S. Pat. Nos. 5,108,404 and 4,969,888 to Scholten et al., describe a system for fixing osteoporotic bone using an inflatable balloon which compacts the bone to form a cavity into which bone cement is injected after the balloon is withdrawn. The invention requires the use of fluoroscopy to monitor the injection and to help guard against cement leakage through fissures in bone. Unfortunately, such leakage is known to occur in spite of these precautions. Since such leakage may cause serious injury, including paralysis, an improved device and method is needed.  
           [0005]    U.S. Pat. No. 5,972,015 to Scribner et al., describes a system of deploying a catheter tube into the interior of a vertebra and expanding a specially configured nonporous balloon therewithin to compact cancellous bone to form a cavity. The Scribner patent approach utilizes a non-porous balloon which is inflated within the bone to cause compression. The cavity thus formed, may then be filled with bone cement. Unfortunately, the bag used by Scribner may be ruptured during expansion to compact cancellous bone due to sharp projections found within the cavity to be expanded. Filling the cavity eventually formed could allow leakage of bone cement out of the bone against vessels or nerves which may cause undesirable complications.  
           [0006]    The present invention involves an improvement of all of the previous techniques and avoids complications that could occur with the system of U.S. Pat. No. 5,972,015.  
           [0007]    All U.S. patents, applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.  
           [0008]    The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. § 1.56(a) exists.  
         SUMMARY OF THE INVENTION  
         [0009]    The invention provides a method of correcting numerous bone abnormalities including bone tumors and cysts, avascular necrosis of the femoral head, tibial plateau fractures and compression fractures of the spine. The abnormality may be corrected by first accessing and boring into the damaged tissue or bone and reaming out the damaged and/or diseased area using any of the presently accepted procedures, or the damaged area may be prepared by expanding a bag within the damaged bone to compact cancellous bone. After removal and/or compaction of the damaged tissue the bone must be stabilized.  
           [0010]    In cases in which the bone is to be compacted, the methods and devices of this invention employ a catheter tube attached to an inflatable porous fabric bag as described in U.S. Pat. Nos. 5,549,679 and 5,571,189 to Kuslich, the disclosures of which are incorporated herein by reference. Those bags may be inflated with less fear of puncture and leakage of the inflation medium than thin walled rubber balloons. They may also be used over a Scribner balloon to protect the balloon from breakage and eventually seepage.  
           [0011]    The devices of U.S. Pat. Nos. 5,549,679 and 5,571,189 to Kuslich, additionally provide the surgeon with the advantage of safely skipping the first balloon inflation steps of Scribner and Scholten, by expanding the bag through introduction of fill material, such as a bone repair medium thereby correcting the bony defect and deformity and stabilizing it in one step of the procedure.  
           [0012]    As indicated above, the damaged bone may be removed by any conventional reamer. Examples of reamers are described in U.S. Pat. No. 5,015,255; U.S. patent application Ser. No. 09/782,176, to Kuslich et al., entitled “Expandable Reamer” and filed Feb. 13, 2001; and U.S. patent application Ser. No. 09/827,202 to Peterson et al., entitled “Circumferential Resecting Reamer Tool,” filed Apr. 5, 2001. Other examples of reamers are known and may be used. After the damaged bone or tissue has been removed, bone repair medium may then be inserted into the cavity thus formed, via a catheter and expandable fabric bag as described in U.S. Pat. Nos. 5,549,679 and 5,571,189.  
           [0013]    Alternatively, either a smaller than desired cavity may be formed into the bone to be enlarged by compaction or the cavity may be formed only by compaction through introduction of fill material into the bag. In either case, the bag may be positioned over the inflation balloon which is then inflated within the bone site to provide the degree of compaction required. The bag may then be filled with fill material, such as bone repair medium while the balloon remains in place within the bag. Alternatively, the balloon may be removed from the bag prior to filing the bag. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    A detailed description of the invention is hereafter described with specific reference being made to the drawings in which:  
         [0015]    [0015]FIG. 1 is a side elevational view of a vertebra that is fractured and in need of repair;  
         [0016]    [0016]FIG. 2 is a side view of the vertebra of FIG. 1 being reamed out with a reaming tool from the anterior approach;  
         [0017]    [0017]FIG. 3 is a top view of the vertebra of FIG. 1 showing the reamer forming a pair of cavities within the vertebra from the anterior approach;  
         [0018]    [0018]FIG. 4 is a side elevational view of the vertebra of FIG. 2 showing placement of an expandable fabric bag of the invention;  
         [0019]    [0019]FIG. 5 is a top elevational view of the vertebra of FIG. 3 showing a second of two expandable fabric bags of the invention being positioned;  
         [0020]    [0020]FIG. 6 is a side view of a vertebra being reamed from a posterior approach;  
         [0021]    [0021]FIG. 7 is a top view of the vertebra of FIG. 6 with a bag in place and a second cavity being reamed;  
         [0022]    [0022]FIG. 8 is a side elevational view of the vertebra of FIG. 6 with an expandable fabric bag of the invention in place;  
         [0023]    [0023]FIG. 9 is a top view of the vertebra of FIG. 7 with one bag inflated and the second bag being deployed;  
         [0024]    [0024]FIG. 10 is a side elevational view showing the vertebra cavity being expanded with an expandable fabric bag about an inflation device in cross-section;  
         [0025]    [0025]FIG. 11 shows the bag system of FIG. 10 with the vertebra in phantom to show the bag system;  
         [0026]    [0026]FIG. 12 is a view similar to FIG. 10 showing a different approach to the interior of the vertebra;  
         [0027]    [0027]FIG. 13 is a view similar to FIG. 11 showing the approach of FIG. 12;  
         [0028]    [0028]FIG. 14 shows the bag of FIG. 12 in a closed, filled and expanded position;  
         [0029]    [0029]FIG. 15 is a top view of the bag system of FIG. 12 being inflated through a catheter tube;  
         [0030]    [0030]FIG. 16 shows a femoral head with avascular necrosis;  
         [0031]    [0031]FIG. 17 shows the femoral head of FIG. 16 being reamed out;  
         [0032]    [0032]FIG. 18 shows placement of a bag system of the invention within the cavity in the femoral head;  
         [0033]    [0033]FIG. 19 is a side elevational view of a tibial plateau fracture;  
         [0034]    [0034]FIG. 20 is a side view of the fracture of FIG. 19 with a cavity being formed with a reamer; and  
         [0035]    [0035]FIG. 21 shows the tibial plateau fracture repaired with an expanded inflatable fabric bag in place. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]    In the following detailed description, similar reference numerals are used to depict like elements in the various figures.  
         [0037]    [0037]FIG. 1 shows a typical vertebra  10  having compression fractures  12  that is in need of repair. As indicated above the damaged portion of the vertebra  10  may be reamed out, compacted, or otherwise repaired. For example, FIG. 2 shows a reamer  14  entering the vertebra  10  anteriorly to make an opening  15  and cavity  16 . Alternatively, multiple cavities  16  may be formed such as is shown in FIG. 3.  
         [0038]    As previously mentioned, the damaged portion of the vertebra  10  may be compacted in addition to or instead of being reamed out. In FIG. 4, a delivery tube or catheter  20  is seen in the process of delivering an expandable fabric bag  22  into the vertebra  10  or into a cavity  16  present therein. As indicated, the cavity  16  may have been created through reaming, compaction by the bag  22  or other device, or by other means. Once the bag  22  is positioned within the vertebra  10 , the bag  22  may be inflated or expanded to the limits of the cavity  16  thus formed through insertion or injection of fill material  19  into the interior  21  of the bag  22 .  
         [0039]    [0039]FIG. 5 shows a single filled expandable fabric bag  22  in place with a second expandable bag which is being inserted and expanded within the cavity  16 .  
         [0040]    FIGS.  6 - 9  illustrate a procedure in which the opening  15  and cavity  16  are created posteriorly. Regardless of the direction through which the vertebra  10  is operated on, in all forms, the cavity  16  which is formed is then filled with acceptable bone replacement material.  
         [0041]    Bone replacement material  19  may be one or more of the following, or any other biocompatible material judged to have the desired physiologic response:  
         [0042]    A) Demineralized bone material, morselized bone graft, cortical, cancellous, or cortico-cancellous, including autograft, allograft, or xenograft;  
         [0043]    B) Any bone graft substitute or combination of bone graft substitutes, or combinations of bone graft and bone graft substitutes, or bone inducing substances, including but not limited to: Tricalcium phosphates, Tricalcium sulfates, Tricalcium carbonates, hydroxyapatite, bone morphogenic protein, calcified and/or decalcified bone derivative; and  
         [0044]    C) Bone cements, such as ceramic and polymethylmethacrylate bone cements.  
         [0045]    The bone replacement material is inserted into the bag  22  via a needle, catheter  20  or other type of fill tool. The bone replacement material expands the bag to the limits of the cavity  16 .  
         [0046]    The inventive bag  22  may be a small fabric bag, from about one to about four cm in diameter, being roughly spherical in shape, although other elliptical shapes and other geometric shapes may be used. The bag is pliable and malleable before its interior space  21  is filled with the contents to be described. The material of the bag  22  may be configured to take on the shape of the cavity in which the bag is placed. While in this initial condition, the bag may be passed, uninflated, through a relatively small tube or portal, perhaps about three mm to about one cm in diameter.  
         [0047]    The bag  22 , such as may best be seen in FIG. 9, is constructed in a special and novel way. The bag  22  may be constructed of a fabric  23 . Fabric  23  may be woven, knitted, braided or form-molded to a density that will allow ingress and egress of fluids and solutions and will allow the ingrowth and through-growth of blood vessels and fibrous tissue and bony trabeculae, but the fabric porosity is tight enough to retain small particles of enclosed material, such as ground up bone graft, or bone graft substitute such as hydroxyapatite or other osteoconductive biocompatible materials known to promote bone formation. The fabric  23  defines a plurality of pores  25 . Generally, the pores  25  of the fabric  23  will have a diameter of about 0.25 mm or less to about 5.0 mm. The size is selected to allow tissue ingrowth while containing the material packed into the bag. If bone cement or other material is used which will not experience bone ingrowth, the pores  25  may be much tighter to prevent egress of the media from within the bag  22  out into the cavity  16 . This prevents leakage that could impinge upon nerves, blood vessels or the like if allowed to exit the bone.  
         [0048]    One or more of the pores  25  may be used as a fill opening  27 , wherein the fabric  23  may be manipulated to enlarge a pore to a diameter potentially greater than 5 mm but no more than about 1 cm. Preferably, the fill opening  27  is less than about 5 mm in diameter. Such a pore/fill opening  27  is sufficiently large to allow a catheter, needle, fill tube or other device for inserting or injecting fill material to pass through the fabric  23  and into the interior  21  of the bag  22  without damaging the integrity of the bag  22 .  
         [0049]    When the bag  22  is fully filled with fill material, the bag will form a self-retaining shape which substantially fills the cavity  16 . Once sufficiently full, the fill tool used to place fill material into the bag interior  21  is removed from the opening  27 . Where the opening  27  is not a pore  25  but rather a separate and distinct opening in the bag  22 , the opening  27  may have a set diameter which requires sealing such as by tying, fastening, welding, gluing or other means of closing the opening  27  after the bag has been filled. Where the opening  27  is a pore  25 , upon removal of the catheter or fill tool from the opening  27  the fabric  23  will contract to reduce the diameter of the opening  27  to be substantially similar to that of the other pores  25 .  
         [0050]    The size and density of the pores determine the ease or difficulty with which materials may pass through the mesh. For instance, very small pores (&lt;0.5 mm) would prohibit passage of all but the smallest particles and liquids. The pore size and density could be controlled in the manufacturing process, such that the final product would be matched to the needs of the surgeon. For example, if methylmethacrylate bone cement were to be used, the pore size would need to be very small, such as about less than 0.5 mm to about 1.0 mm, whereas, when bone graft or biocompatible ceramic granules are used, pore sizes ranging from about 1.0 mm to about 5.0 mm or more may be allowed. The fact that the fabric  23  is properly porous would allow it to restrict potentially dangerous flow of the fill material outside the confines of the bag.  
         [0051]    The fabric is light, biocompatible, flexible and easily handled, and has very good tensile strength, and thus is unlikely to rip or tear during insertion and inflation. When the device is inflated, the device expands to fill a previously excavated cavity  16 .  
         [0052]    The use of the term “fabric” herein is meant to include the usual definition of that term and to include any material that functions like a fabric, that is, the “fabric” of the invention must have a plurality of pores  25  through which material and fluid flow is allowed under the terms as described, and the “fabric” must be flexible enough to allow it to be collapsed and inserted into an opening smaller than the inflated bag size.  
         [0053]    The bag  22  need not be woven and may be molded or otherwise formed as is well known in the art. The preferred material may provide the ability to tailor bioabsorbance rates. Any suture-type material used medically may be used to form the bag  22 . The bag may be formed of plastic or even metal. In at least one embodiment, bag  22  is formed using a combination of resorbable and/or nonresorbable thread. Bag  22  may include a fill opening  27  which may be a bushing that could be a bioabsorbable and/or nonbioabsorbable plastic, ceramic or metal. The opening  27  may also be hydroxyapatite, or it could be plastic or metal. The opening  27  may also be characterized as a pore  25 , wherein a pore  25  of the fabric  23  has been expanded to allow a catheter  20  or other fill device to pass into the interior  21  of the bag  22 . The bag  22  could be formed from a solid material to which perforations are added. The bag  22  may be partially or totally absorbable, metal, plastic, woven, solid, film or an extruded balloon.  
         [0054]    In embodiments of the present invention a damaged tissue of a body, such as a vertebra  10  may be treated in accordance with the following procedures such as are depicted in FIGS.  1 - 9 :  
         [0055]    Initially, the vertebra  10  needing repair is surgically exposed by forming at least one cavity  16 . The cavity or cavities  16  may be formed by several different means such as by reaming. Reaming may be accomplished by several means such as including the use of a reamer  14  such as, for example, the Kuslich Expandable Reamer, U.S. Pat. No. 5,015,255, the entire content of which is incorporated herein by reference. Next, the unexpanded mesh bag or Expandable Fabric Bag Device (EFBD)  22  is inserted into the cavity or cavities via catheter  20  or other means. At some point, the fill material  19  is prepared for insertion or injection into the EFBD  22 . Following preparation of the fill material  19 , the material is injected or otherwise inserted into the bag  22  using sufficient pressure to fill the bag  22  to its expanded state, thus producing rigidity and tension within the cavity or cavities  16  to reach the degree of correction required by virtue of the compression fractures. Finally, the fill opening  27  is closed to prevent egress of inflation material  19 .  
         [0056]    FIGS.  10 - 15  show a form of the invention in which a balloon  30  and catheter tube  32  is employed. The balloon  30  is surrounded by an expandable fabric bag  22  to protect the balloon  30  from being punctured during the inflation steps and to remain in place to prevent undesired egress of material injected into the cavity formed in the bone. Balloon  30  may be any medical-grade elastomeric balloon. The balloon  30  may be constructed from latex, urethanes, thermoplasic elastomers or other substances suitable for use as an expandable member. Examples of suitable balloons include, but are not limited to: balloons utilized with the FOGARTY.RTM. occlusion catheter manufactured by Baxter Healthcare Corporation of Santa Ana, Calif.; balloons of the type described in U.S. Pat. No. 5,972,015 to Scribner et al., and others. The methods involve placement of the expandable fabric bag  22  of the invention about the balloon  30  of the Scribner et al. device. The expandable bag  22  is left in place before the cavity  16  is filled with bone substitute or bone cement. The expandable fabric bag  22  prevents breakage of the balloon  30  and greatly limits the ability of fill material from leaking out of the cavity through bone fissures where it could cause damage.  
         [0057]    As may best be seen in FIGS. 11, 13 and  15 , the bag  22  may include a neck  29  which extends outwardly from the bag  22  to completely overlap the shape of balloon  30 . The bag  22  and/or balloon  30  may each have a variety of shapes and sizes.  
         [0058]    If desired, the expandable fabric bag  22  may be used as the sole inflation device, eliminating the Scribner et al. balloon  30  if the fabric porosity is tight and the inflation media is reasonably viscous.  
         [0059]    While many of the previous embodiments have described the use of the bag  22  for repair of tissue such as a spinal body, in FIGS.  16 - 18  show how the bag  22  may be used in treating avascular necrosis of the femoral head. In FIG. 16, a femoral head  40  is shown which is in need of repair. FIG. 17 shows the femoral head being reamed out with a reamer  14 , such as previously described. The reamer  14  forms a cavity  16 . In FIG. 18, a bag  22  is shown within the cavity  16  formed within the femoral head  40 . The opening  27  of the bag  22  is closed off after being filled and expanded with bone substitute material.  
         [0060]    In an alternative embodiment, the Scribner et al. balloon, as previously described, may also be used with the bag  22  for repair of the femoral head  40 .  
         [0061]    Turning to an embodiment of the invention shown in FIGS.  19 - 21 , a tibial plateau  48  is shown having a fracture  50 . The fracture  50  is repaired by forming a cavity  16  with a reamer  14 , such as is shown in FIG. 20. As is shown in FIG. 21, once cavity  16  is properly reamed, bag  22  may be inserted therein and filled with bone repair media  19 .  
         [0062]    Other tissue and bone abnormalities may also be treated with the inventive methods and bag  22  described herein. The present invention is not limited to only treatment of spinal bodies, femoral heads, and tibial plateaus. The bag  22  and the methods of treatment described herein, may be utilized throughout a mammalian body to treat many types of bone and tissue abnormalities including those described herein as well as others.  
         [0063]    In addition to being directed to the specific combinations of features claimed below, the invention is also directed to embodiments having other combinations of the dependent features claimed below and other combinations of the features described above.  
         [0064]    The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to.” Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.  
         [0065]    Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g., each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below (e.g., claim  3  may be taken as alternatively dependent from claim  2 ; claim  5  may be taken as alternatively dependent on claim  3 , claim  6  may be taken as alternatively dependent from claim  3 ; claim  7  may be taken as alternatively dependent from claims  3 ,  5  or  6 ; etc.).