Abstract:
A bone tamp for creating channels within bone tissue. The bone tamp includes an elongated member that is deformable from a first generally non-linear configuration to a second generally linear configuration for insertion into bone tissue. As the elongated member is deployed into bone tissue, it transitions from the linear configuration into the non-linear configuration within the bone tissue. The elongated member is capable of being deformed back into the generally linear configuration for withdrawal from the bone tissue.

Description:
[0001]    The present application is a continuation of U.S. patent application Ser. No. 12/020,396, filed Jan. 25, 2008, which is a continuation-in-part of U.S. patent application Ser. No. 11/464,782, a continuation-in-part of U.S. patent application Ser. No. 11/464,790, a continuation-in-part of U.S. patent application Ser No. 11/464,793, a continuation-in-part of U.S. patent application Ser. No. 11/464,807, a continuation-in-part of U.S. patent application Ser. No. 11/464,812 and a continuation-in-part of U.S. patent application Ser. No. 11/464,815, all of which were filed on Aug. 15, 2006 and claim the benefit of Provisional Patent Application No. 60/708,691, filed Aug. 16, 2005, U.S. Provisional Patent Application No. 60/738,432, filed Nov. 21, 2005 and U.S. Provisional Patent Application No. 60/784,185, filed Mar. 21, 2006, all of the above of which are hereby incorporated herein by reference. U.S. patent application Ser. No. 12/020,396 also claims the benefit of U.S. Provisional Application No. 60/886,838, filed Jan. 26, 2007, U.S. Provisional Application No. 60/890,868, filed Feb. 21, 2007, and U.S. Provisional Application No. 60/936,974, filed Jun. 22, 2007, all of which are hereby incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present disclosure generally relates to apparatus and methods for the treatment of bone conditions and, more particularly, to apparatus and methods for forming passageways within bone tissue, such as bone tamps, and interdigitating bone filler material with bone tissue. 
       BACKGROUND OF INVENTION 
       [0003]    Bones or portions of bones often comprise an outer relatively hard layer referred to as cortical bone and inner material referred to as cancellous bone. A variety of physical conditions can cause cancellous bone to become diseased or weakened. Such conditions can include, for example, osteoporosis, avascular necrosis, cancer or trauma. Weakened cancellous bone can result in an increased risk of fracture of the cortical bone surrounding the cancellous bone, because the diseased or weakened cancellous bone provides less support to the exterior cortical bone than healthy cancellous bone. 
         [0004]    One common condition that is caused by diseased or damaged cancellous bone is vertebral compression fractures. A vertebral compression fracture is a crushing or collapsing injury to one or more vertebrae. One of the leading causes, but not an exclusive cause, of vertebral compression fractures is osteoporosis. Osteoporosis reduces bone density, thereby weakening bones and predisposing them to fracture. The osteoporosis-weakened vertebrae can collapse during normal activity and are also more vulnerable to injury from shock or other forces acting on the spine. In severe cases of osteoporosis, actions as simple as bending can be enough to cause a vertebral compression fracture. 
         [0005]    While the vertebral compression fractures may heal without intervention, the crushed bone may fail to heal adequately. Moreover, if the bones are allowed to heal on their own, the spine may be deformed to the extent the vertebrae were compressed by the fracture. Spinal deformity may lead to other adverse conditions, such as, breathing and gastrointestinal complications, and adverse physical effect on adjacent vertebrae. 
         [0006]    Minimally invasive surgical techniques for treating vertebral compression fractures are becoming more and more common. One such technique used to treat vertebral compression fractures is injection of bone filler material into the fractured vertebral body. This procedure is commonly referred to as percutaneous vertebroplasty. More specifically, vertebroplasty involves inserting an inject needle into bone material in the vertebra and injecting bone filler material (for example, bone cement, allograph material or autograph material) into the collapsed vertebra to stabilize and strengthen the crushed bone. 
         [0007]    Another type of treatment for vertebral compression fractures is known as Kyphoplasty. Kyphoplasty is a modified vertebroplasty treatment that uses one or two balloons, introduced into the vertebra. First a cannula or other device is inserted into the vertebra. The cannula may have one or more balloons associated with it or another device may be inserted with balloons. As the balloons are inflated, the balloons push the cancellous bone outwardly, crushing or compacting the cancellous bone to create a cavity, which significantly alters the natural structure of the cancellous bone. The balloons are then deflated and removed, leaving a cavity. Bone cement is injected into the cavity to stabilize the fracture. 
       SUMMARY OF THE INVENTION 
       [0008]    The present disclosure relates to apparatus and methods that are employed to treat bone tissue, such as cancellous bone tissue. More particularly, the present disclosure relates to a bone tamp and methods of use thereof that can be employed to create one or more passageway channels within bone tissue for any number of bone treatment procedures. For example, the bone tamp can be employed to created a channel or pathway in cancellous bone tissue of a vertebral body in a vertebroplasty-type procedure. 
         [0009]    One aspect of the present disclosure relates to apparatus for forming channels in bone tissue. The apparatus includes an elongated member adapted for being deployed into and withdrawn from bone tissue. The elongated member is deformable from an original or as-made generally non-linear configuration into a modified or ready generally linear configuration for insertion of the elongated member into bone tissue. As the elongated member is inserted into the bone tissue, the elongated member returns or transitions, in one embodiment by self-forming, back into the original or as-made generally non-linear configuration within the bone tissue. The elongated member is also deformable into a generally linear configuration for withdrawal from the bone tissue. 
         [0010]    Another aspect of the present invention relates to a method for creating a passageway channel within bone tissue. The method includes providing an elongated member having a generally non-linear configuration and applying an external force to change the shape of the elongated member into a more linear configuration. While in the more-linear configuration, the elongated member is inserted into bone tissue and the external force is removed to allow the elongated member to substantially return to the generally non-linear configuration. After insertion into bone tissue, the elongated member may be withdrawn from the bone tissue to create a passageway or channel within the bone tissue. 
         [0011]    A further aspect of the present disclosure relates to a method of interdigitating bone filler material and bone tissue. The method includes providing an elongated member which is constrained in a generally linear configuration, and which member is biased to form a non-linear configuration when the constraint is removed. While in the generally linear configuration, the elongate member is inserted into bone tissue and the constraint is removed from the elongated member to allow the elongated member to assume the generally non-linear configuration within the bone tissue. The elongated member may thereafter be withdrawn from the bone tissue, thereby creating a passageway or channel within the bone tissue. After the channel has been created, bone filler material, such as PMMA, bone paste, bone cement, allograph, autograph or any other suitable flowable material, is injected into the channel to interdigitate the flowable material with the bone tissue. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0012]    In the course of this description, reference will be made to the accompanying drawings, wherein: 
           [0013]      FIG. 1  is a partial side view of a normal human vertebral column; 
           [0014]      FIG. 2  is comparable to  FIG. 1 , depicting a vertebral compression fracture in one of the vertebral bodies; 
           [0015]      FIG. 3  is a perspective view of one embodiment of a bone tamp of the present disclosure, shown in a helical or coiled configuration; 
           [0016]      FIG. 4  is a vertical cross-sectional view of the bone tamp of  FIG. 3 ; 
           [0017]      FIG. 5  is a perspective view of a deployment cannula, shown with a bone tamp of the present disclosure in a generally linear configuration within the cannula for deployment; 
           [0018]      FIG. 6  is a perspective view of the deployment cannula of  FIG. 5 , shown with the bone tamp partially ejected from the deployment cannula and in a deployed configuration; 
           [0019]      FIG. 7  is top a perspective view of a vertebra having portions broken away to show the distal end of a deployment cannula inserted within the vertebral body; 
           [0020]      FIG. 8  is a top perspective view of the vertebra of  FIG. 7  having portions broken away to show a bone tamp partially extending out of the distal end of the deployment cannula and deployed within the cancellous bone of the vertebral body; 
           [0021]      FIG. 9  is a top perspective view of the vertebra of  FIG. 8  having portions broken away to show the bone tamp fully deployed within the cancellous bone of the vertebral body; 
           [0022]      FIG. 10  is a cross-sectional view of the vertebra of  FIG. 9 , showing the bone tamp fully deployed; 
           [0023]      FIG. 11  is a top perspective view of the vertebra of  FIG. 9 , shown after the bone tamp has been withdrawn from the vertebral body, portions of the vertebral body have been broken away to show the passageway or channel created within the cancellous bone of the vertebral body; 
           [0024]      FIG. 12  is a cross-sectional view of the vertebra of  FIG. 11 ; 
           [0025]      FIG. 13  is a top cross-sectional view of the vertebra of  FIG. 11  shown after the channel has been formed and having a bone filler material injection needle inserted into the channel within the cancellous bone; and 
           [0026]      FIG. 14  is a cross-sectional view of the vertebra of  Fig.12  shown with bone filler material within the channel and interdigitating with the cancellous bone. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Although detailed embodiments of the present subject matter are disclosed herein, it is to be understood that the disclosed embodiments are merely exemplary, and the subject matter may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting the subject matter claimed, but merely as examples to illustrate and describe the subject matter and various aspects thereof. 
         [0028]    As pointed out earlier, the present disclosure pertains to apparatus and methods for forming passageways or channels in bone tissue and interdigitating bone filler material with bone tissue. The apparatus and methods will be described by way of example, but not limitation, in relation to procedures within the vertebral body. The apparatus and methods may be used to treat bone tissue in other areas of the body as well. Moreover, although the bone tamp described herein will be described by way of example, but not limitation, in conjunction with methods for interdigitating bone filler material, the bone tamp and methods of use thereof also can be used to create passageways or channels in bone tissue for virtually any purpose or procedure where such passageways or channels are desired. 
         [0029]      FIG. 1  illustrates a section of a healthy vertebral (spinal) column, generally designated as  10 , free of injury. The vertebral column  10  includes adjacent vertebrae  12   a,    12   b  and  12   c  and intervertebral disks  14   a,    14   b,    14   c  and  14   d  separating adjacent vertebrae. The vertebrae, generally designated as  12 , include a vertebral body  16  that is roughly cylindrically shaped and comprised of spongy inner cancellous bone surrounded by compact bone (referred to as the cortical rim). The body  16  of the vertebra is capped at the top by a superior endplate and at the bottom by an inferior endplate made of a cartilaginous layer. On either side of the vertebral body  16  are the pedicles  18 , which lead to the spinal process  20 . Other elements of the vertebra include the transverse process  22 , the superior articular process  24  and the inferior articular process  26 . 
         [0030]    In vertebral compression fractures the vertebral body may be fractured from impact (even if healthy) or suffer fractures that result from weakening of the cortical rim such as from osteoporosis. When weakened by osteoporosis, the vertebra is increasingly subject to fracture due to routine forces from standing, bending or lifting. 
         [0031]      FIG. 2  illustrates a damaged vertebral column, generally designated as  28 , with a vertebral body  30  of a vertebra  32  suffering from a compression fracture  34 . The vertebral body  30  suffering from the compression fraction  34  becomes typically wedge shaped and reduces the height of both the vertebra  32  and vertebral column  28  on the anterior (or front) side. As a result, this reduction of height can affect the normal curvature of the vertebral column  28 . If left untreated, the vertebral body may further collapse and fracture causing additional pain and complications. 
         [0032]    Turning now to a detailed description of illustrated embodiments described herein. The apparatus or device of the present disclosure, falls generally into the class of medical devices known as bone tamps osteotome. Bone tamps per se are not new, and the term generally refers to a device with an elongated shaft for insertion into bone. Such bone tamps were known long before the development of vertebroplasty and kyphoplasty. The present subject matter is referred to as a bone tamp because it is inserted into bone tissue, forming a passageway or channel therethrough by reason of its insertion, just as bone tamps have done since their early development. 
         [0033]      FIG. 3  shows a perspective view of one embodiment of the present bone tamp  36  in its initial or original, as-manufactured configuration, and  FIG. 4  shows a vertical cross-sectional view of bone tamp  36 . In this embodiment, bone tamp  36  is comprised of an elongated member  38 , such as a shaft, thread or ribbon, having a rectangular cross-section. In other embodiments, elongated member  38  can have a variety of cross-sectional shapes and profiles, such as round or other simple or complex geometric profiles. 
         [0034]    In this initial configuration, bone tamp  36  has a generally helical or coiled configuration. The pitch of the helical configuration can vary depending on the desired application. In other words, the spacing between each winding  40  can vary. In the embodiment shown, the helical configuration has a tight pitch and each turn or winding  40   a  is wound on top of the previous winding  40   b  to form a plurality of stacked windings with little or no spacing between each winding. In its initial configuration, bone tamp  36  includes or defines an innerspace or resident volume  42 . As used herein, “resident volume” is intended to refer generally to a structural characteristic of bone tamp  36  in its helical configuration in that the bone tamp has a structure that generally defines a resident volume. The resident volume  42  is not necessarily a volume completely enclosed by bone tamp  36  and can be any volume generally defined by the bone tamp. The resident volume is not necessarily empty and can contain material, such as cancellous bone. 
         [0035]    Bone tamp  36  can be comprised of any suitable material, but preferably comprises a shape memory material. The shape memory material can be any suitable material, the shape of which can be changed upon application of external force, and which substantially returns to its initial shape upon remove of the external force. Such shape memory materials can include, for example, Nitinol (NiTi) or other suitable alloy (Cu—Al—Ni, Ti—Nb—Al, Au—Cd, etc.) or a shape memory polymer. Bone tamp  36  can be formed into the initial or original helical configuration by any suitable method know in the art, such as the method described in co-owned U.S. patent application Ser. No. 11/464,782, which is incorporated by reference above. 
         [0036]      FIGS. 5 and 6  are perspective views generally showing the deployment of bone tamp  36  through a deployment cannula  44 . Bone tamp  36  is first formed into the initial or original helical or coil shape seen in  FIG. 3 . Referring to  FIG. 5 , bone tamp  36  (partially shown in phantom) can be unwound or drawn or forced into a substantially linear or deployment configuration by insertion into a lumen  50  of deployment cannula  44  for delivery. Cannula  44  constrains or otherwise exerts an external force on bone tamp  36  to deform and retain bone tamp  36  in a generally straight configuration as the bone tamp is passed into the cannula. The modified or deployment ready shape of bone tamp  36  is substantially linear, in that the shape can be perfectly straight or the shape could include slight bends or zigzags within the cannula. 
         [0037]    Upon exiting opening  46  in a distal end portion  48  of cannula  44 , the external force is removed from bone tamp  36  and the bone tamp, by change of configuration, returns to its initial or original shape, or nearly so, as illustrated in  FIG. 6 . As shown in the partially exited position, a coiled portion of bone tamp  36  is outside of cannula  44  in the original state and the remaining portion of bone tamp  36  is inside the cannula in a modified or ready constrained shape. Bone tamp  36  can be retracted back into cannula  44  and back into the constrained shape as illustrated in  FIG. 5  or further ejected from the cannula to assume its original shape. 
         [0038]    In one embodiment, opening  46  and lumen  50  of the cannula  44  have a complementary or generally similar cross-sectional shape as bone tamp  36 , which aids in deploying the bone tamp in the desired orientation. In the embodiment shown, bone tamp  36  can be advanced or retracted through cannula  44  with the aid of a pushrod  52 . Proximal end  54  of cannula  44  may have a knob or handle  56  or other structure for ease of use and proximal end  58  of the pushrod  52  also may have a knob or handle  60  as well. Alternatively, bone tamp  36  can be advanced and retracted through cannula  44  by any suitable drive or gear mechanism. 
         [0039]      FIGS. 7-12  illustrate an exemplary method of employing the bone tamp  36  to form a channel within the cancellous bone tissue of a vertebral body. This is, of course, not the only procedure in which the bone tamp may be employed.  FIG. 7  is a perspective view of a vertebra  62 . As generally described above, vertebral body  70  of vertebra  62  includes cancellous bone tissue  68  surrounded by cortical rim  63 . The distal end portion  64  of a deployment cannula  66  is inserted into the cancellous bone  68  of vertebral body  70  through a percutaneous transpedicular access port  72 . Portions of vertebra  62  shown in  FIGS. 7-9  have been broken way to show the location of the distal end portion of the cannula and the bone tamp within the cancellous bone of the vertebral body. 
         [0040]    The transpedicular access port  72  can be made by using standard percutaneous transpedicular techniques that are well known in the art. Typically, such standard techniques include the use of minimally invasive vertebral body access instruments, such as trocars, access needles and working cannulas. If a working cannula is used, the working cannula is inserted into the transpedicular access port  72  and deployment cannula  66  is inserted into the vertebra  62  through the working cannula. Depending on the particular procedure, the deployment cannula can also be inserted into the cancellous bone of the vertebral body through other approaches as well, such as from lateral or anterior approaches. 
         [0041]    In the illustrated embodiment, the distal end portion  64  of the deployment cannula  66  is centrally positioned within the vertebral body  70 . However, the deployment cannula may be positioned at other locations depending on the desired application. Once deployment cannula  66  is in the desired position within the vertebral body  70 , bone tamp  36 , in its constrained or generally linear configuration, is advanced through deployment cannula  66  and out of opening  74  in distal end portion  64  of deployment cannula  66 , as shown in  FIG. 8 . In this embodiment, opening  74  comprises an opening in the side of distal end portion  64  of deployment cannula  66 . 
         [0042]    Upon exiting deployment cannula  66 , the external force constraining bone tamp  36  in the generally linear configuration is removed and the bone tamp, due to its shape retention characteristics, begins to substantially revert or self-form into its initial or original helical or coiled shape. Thus, the deployed configuration of bone tamp  36  is substantially the same as its initial or original configuration. 
         [0043]    Referring to  FIGS. 9 and 10 , as bone tamp  36  advances out of the distal end portion  64  of deployment cannula  66 , bone tamp  36 , due to its mechanical strength and shape retention characteristics, penetrates and transverses through the relatively spongy cancellous bone to create a cylindrical or helically shaped channel or passageway therethrough. In the embodiment shown, the distal end portion  76  of bone tamp  36  has a generally blunted end. In alternative embodiments, distal end portion  76  can have other configurations, such as for example, pointed and sharp surfaces, which aid the bone tamp in penetrating and traversing through the bone tissue. 
         [0044]    As shown in  FIGS. 9 and 10 , the individual loops or windings  40  of bone tamp  36  stack-up one adjacent to the other to create a generally cylindrical structure having a resident volume  42  filled with cancellous bone. Specifically, bone tamp  36  winds through cancellous bone  68  of vertebral body  70  so that undisturbed cancellous bone  78  is located within the resident volume  42 . Moreover, depending on the desired application, each winding  40  may be in contact with the adjacent windings or windings  40  may be spaced apart, or bone tamp  36  may contain a combination of touching and spaced apart windings  40 . 
         [0045]    The deployment of bone tamp  36  can be monitored by fluoroscopic imaging or any other suitable type imaging to help ensure that the bone tamp is forming the desired channel for the particular procedure. Monitoring the deployment of the bone tamp provides several benefits, such as, ensuring the bone tamp is being deployed along the desired path and in the desired orientation. 
         [0046]    After the desired portion of bone tamp  36  has been deployed, i.e., a sufficient length of the bone tamp has been deployed to create a channel of the desired size, bone tamp  36  may be retracted from cancellous bone  68  of vertebral body  70  and back into deployment cannula  66 . As bone tamp  36  is retracted into the deployment cannula  66 , the cannula again applies an external force on the bone tamp and the bone tamp is forced into its generally linear modified or ready configuration. After bone tamp  36  has been fully or substantially retracted into deployment cannula  66 , the bone tamp and deployment cannula are withdrawn from the vertebra. As shown in  FIGS. 11 and 12 , withdrawing bone tamp  36  from the vertebral body  70  leaves a generally cylindrical or helical shaped passageway channel  80  within cancellous bone  68 . 
         [0047]    As mentioned above, the above described bone tamp and methods of use thereof are not limited to the treatment of vertebral bone tissue and can be used to treat bone tissue in other areas of the body as well. Additionally, the bone tamp can be used in conjunction with a variety of different procedures, such as for example, in a procedure involving interdigitation of bone filler material with bone tissue. One such interdigitation procedure for treating vertebral bodies is illustrated in  FIGS. 13 and 14 . 
         [0048]      FIG. 13  illustrates a top cross-sectional view of vertebra  62  after a channel  80  has been created in the cancellous bone  68  of the vertebral body  70  using the bone tamp and methods described herein. After channel  80  has been created in cancellous bone  68 , a distal end portion  82  of a bone filler injection needle  84  is inserted into vertebral body  70  to access channel  80 . Distal end portion  82  of the bone filler injection needle  84  can be inserted through the same transpedicular access port that was created to insert the bone tamp. Alternatively, distal end portion  82  of the bone filler injection needle  84  can be inserted through a second or different access port, such as a lateral or anterior access port. Moreover, the positioning of distal end portion  82  of the injection needle  84  can be monitored using fluoroscopy to ensure proper positioning of the needle. 
         [0049]    Once the injection needle  84  is in the desired position, bone filler material or flowable material  86  may be injected into the channel  80 , as shown in  FIG. 13 . As the bone filler material  86  progresses through the channel  68 , the bone filler material also begins to interdigitate with the spongy or porous cancellous bone tissue  68 . In other words, the bone filler material migrates or seeps into and through the pores and around the trabeculae of the spongy cancellous bone as illustrated in  FIG. 14 . A variety of factors contribute to amount of interdigitation and such factors can be controlled by a surgeon to achieve a desired result. Such factors can include, but are not limited to, the size of the channel created in the bone tissue, the viscosity and volume of bone filler material injected, the curing rate of the bone filler material and the amount of injection pressure applied during injection of the bone filler material. After the bone filler material has cured, it is contemplated that it will aid in stabilizing and supporting the cancellous bone and surrounding cortical bone, thereby reducing the risk of collapse or fracture while maintaining the original cancellous bone intact and avoiding the compaction of the bone and creation of a cavity as required in Kyphoplasty. 
         [0050]    It will be understood that the embodiments of the present disclosure which have been described are illustrative of some of the applications of the principles of the present invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention, including those combinations of features that are individually disclosed or claimed herein.