Patent Publication Number: US-10327821-B2

Title: Devices and methods for treating vertebral fractures

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Patent Application is a continuation of U.S. patent application Ser. No. 14/478,940, which is a continuation of U.S. patent application Ser. No. 12/686,052, filed Jan. 12, 2010, now issued as U.S. Pat. No. 8,864,773, which claims priority to U.S. Provisional Application No. 61/144,578, filed Jan. 14, 2009, the entire contents of which are herein incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     A minimally invasive distraction and support device and method would have significant application in orthopaedic surgical procedures, including acute and elective procedures to treat bone fractures and degenerative changes of the skeletal system and including vertebral compression fractures, interbody fusion, vertebral disc augmentation or replacement, and other compression fractures and/or non-orthopaedic surgical procedures. 
     A vertebral compression fracture is a crushing injury to one or more vertebrae. Vertebral fractures are generally associated with osteoporosis (the “brittle bone” disease), metastasis, and/or trauma. Osteoporosis reduces bone density, thereby weakening bones and predisposing them to fracture. 
     The osteoporosis-weakened bones can collapse during normal activity. In severe cases of osteoporosis, actions as simple as bending forward can be enough to cause a vertebral compression fracture. Vertebral compression fractures are generally known to be the most common type of osteoporotic fractures. The mechanism of these fractures is one of flexion with axial compression where even minor events may cause damage to the weak bone. While the 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 be deformed to the extent the vertebrae were compressed by the fracture. Spinal deformity may lead to breathing and gastrointestinal complications, and adverse loading of adjacent vertebrae. 
     Vertebral fractures happen most frequently at the thoracolumbar junction, with a relatively normal distribution of fractures around this point. Vertebral fractures can permanently alter the shape and strength of the spine. Commonly, they cause loss of height and a. humped back. This disorder (called kyphosis or “dowager&#39;s hump”) is an exaggeration of the spinal curve that causes the shoulders to slump forward and the top of the back to look enlarged and humped. 
     severe cases, the body&#39;s center of mass is moved further away from the spine resulting in increased bending moment on the spine and increased loading of individual vertebrae. 
     Another contributing factor to vertebral fractures is metastatic disease. When cancer cells spread to the spine, the cancer may cause destruction of part of the vertebra, weakening and predisposing the bone to fracture. 
     Osteoporosis and metastatic disease are common root causes leading to vertebral fractures, but trauma to healthy vertebrae also causes minor to severe fractures. Such trauma may result from a fall, a forceful jump, a car accident, or any event that stresses the spine past its breaking point. The resulting fractures typically are compression fractures or burst fractures. 
     Vertebral fractures can occur without pain. However, they often cause a severe “band-like” pain that radiates from the spine around both sides of the body. It is commonly believed that the source of acute pain in compression fractures is the result of instability at the fracture site, allowing motion that irritates nerves in and around the vertebrae. 
     Various instruments and methods for the treatment of compression-type bone fractures and other osteoporotic and/or non-osteoporotic conditions have been developed. Such methods generally include a series of steps performed by a surgeon to correct and stabilize the compression fracture. A cavity is typically formed in the bone to be treated, followed by the insertion of one or more inflatable balloon-likes device into the bone cavity. Inflation of the balloon-like device causes a compaction of the cancellous bone and/or bone marrow against the inner cortical wall of the bone, thereby resulting in enlargement of the bone cavity and/or reduction of the compression fracture. The balloon-like device is then deflated and removed from the bone cavity. A biocompatible filling material, such as methylmethacrylate cement or a synthetic bone substitute, is sometimes delivered into the bone cavity and allowed to set to a hardened condition to provide internal structural support to the bone. In theory, inflation of the balloons restores vertebral height. However, it is difficult to consistently attain meaningful height restoration. It appears the inconsistent results are due, in part, to the manner in which the balloon expands in a compressible media and the structural orientation of the trabecular bone within the vertebra. 
     For example, it has been found that expansion of the balloon-like device can be difficult to control. Instead, when such a balloon-like device is inflated, expansion occurs along a path of least resistance. As a result, the direction of compaction of the cancellous bone and/or reduction of the compression fracture is not controllable, and expansion occurs in multiple directions and along multiple axes. 
     SUMMARY OF THE INVENTION 
     The present application is generally directed to devices and methods for treating vertebral fractures with one or more bone pins. In one embodiment of a method, a fractured vertebral body may be accessed through a pedicle portion and an opening created therethrough. One or more bone pins may be inserted through the opening. At least one of the inserted bone pins may be inserted to extend across a fracture zone with a proximal portion of the pin engaging a first bone segment and a distal portion engaging a second bone segment. The pin or pins may be manipulated to immobilize the first and second portions of the fractured vertebra. 
     In another embodiment, a system for treating a fractured vertebral bone is disclosed. This system generally comprises a cannulated eyelet configured and dimensioned for installation in a pedicle portion of the vertebral bone to create an access opening into the interior portion of the vertebral body. An elongate cannula may be releasably mountable to the eyelet. The cannula may be moveable over 60 degrees of angulation with respect to the eyelet when mounted thereto. The system may also include a plurality of bone pins. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a vertebral body having a compression fracture displacing its superior and anterior edge; 
         FIG. 2  shows a vertebral body, following treatment of a compression fracture; 
         FIG. 3  is a side view of one embodiment of a bone treatment system according to the invention, shown in a vertebral body in a collapsed position; 
         FIG. 4  is a side view of the system of  FIG. 3 , shown in a vertebral body in a restored position; 
         FIG. 5  is a side view of one embodiment of a bone fixation pin according to the invention; 
         FIGS. 6-7  are side views of alternate embodiments of bone pins according to the invention; 
         FIGS. 8-9  are side views of another embodiment of a bone treatment system according to the invention; 
         FIGS. 10-13  are views of another embodiment of a bone treatment system according to the invention; 
         FIGS. 14-15  are side views of another embodiment of a bone treatment system according to the invention; 
         FIGS. 16-17  are side views of another embodiment of a bone treatment system according to the invention; 
         FIGS. 18-19  are views of another embodiment of a bone treatment system according to the invention; 
         FIGS. 20-21  are views of one embodiment of a minimally invasive disc treatment system according to the invention; and 
         FIG. 22  is a side view of another embodiment of a minimally invasive disc treatment system according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Embodiments of the present invention are generally directed to devices and methods for treating bone fractures. In particular, certain embodiments are directed to minimally invasive distraction and support devices and methods to treat fractures of the vertebral body. 
     The devices and methods are generally described by its application to the vertebral compression fracture, However, in alternate applications, alternate types of fractures including, but not limited to, burst type fractures may also be treated.  FIG. 1  illustrates two vertebrae  10 ,  12 , each with an anterior side  14 , a posterior side  16 , and lateral sides  18  (only one shown). Vertebra  10  is fully intact, while vertebra  12  has a vertebral compression fracture (i.e. the top  20  and bottom  22  of the vertebra have been displaced towards each other). Referring to  FIG. 2 , the vertebral compression fracture of vertebra  12  is shown in a reduced or height restored state (i.e., the top  20  and bottom  22  of the vertebra  12  are distracted or displaced back to or near their original/intact positions). it is known that the force required to reduce the vertebral compression fracture can often be rather high. 
     Referring to  FIGS. 3-7 , one embodiment of a bone fracture distraction device or system  40  is shown. System  40  generally comprises one or more rods, skewers, or pins  42 ,  62  insertable through a cannula  44  to a vertebral body. In one variation, pin  42  may comprise a partially threaded section  46 . In another variation, pins  42  may be completely threaded along its length or completely free from threads. In yet another variation, pins  42  may be cannulated. 
     Referring to  FIGS. 5-7 , exemplary embodiments of pins  42 ,  62  according to the invention are shown, As shown in  FIG. 5 , one embodiment of a pin  42  is a generally thin cylindrical member extending along a longitudinal axis  48  and may have a distal end portion  50  with threads  46  and an enlarged head portion  52  adjacent its proximal end  54 . A hexagonal shaped indentation may be provided adjacent proximal end  54  to accommodate a corresponding shaped driving tool to facilitate rotation of pin  42  during installation. Referring to  FIG. 6 , according to certain embodiments, pin  42  may have threads  46  along its entire length. In general when installed in a bone, head portion  52  acts in conjunction with threaded portion  46  to draw or compress bone segments together. In one variation, the distal tip  54  may be generally blunt or otherwise configured and dimensioned to engage cortical bone. In one embodiment, head portion  52  may have a flange wall  56  extending generally orthogonal to longitudinal axis  48 . In alternative embodiments, flange wall  46  may extend at an angle between about 30 and 45 degrees with respect to longitudinal axis  48 , In still other embodiment, pins  42  may not have a head portion at all, such that the pin profile is substantially cylindrical in shape and may have threads along any or all of its length. In this regard, those skilled in the art will appreciate that such a headless pin may facilitate manipulation of bone fragments or bone portions, such as by skewering, piercing and/or pushing or moving the fragment or bone portion. 
     Referring to  FIG. 7 , another embodiment of an unthreaded pin  62  is shown. Pin  62  is a generally thin cylindrical member extending along a longitudinal axis  64  and may have a tapered distal and proximal end portions  66 ,  68 . In this regard, pin  62  has a shape similar to a toothpick. The shape and dimensional characteristics of pin  62  facilitate lateral insertion of multiple pins  62  against one another. In operation, such a feature may be utilized to treat bone fractures minimally invasively, as described below. 
     Pins  42 ,  62  and cannulated tubes  44  may be provided in kits or sets such that a surgeon user may select among a variety of shaped and sized pins and cannulas to be used in a particular procedure as desired. According to one variation, pins  42 ,  62  may have a diameter D between about 1 mm and about 4 mm. Pins  42 ,  62  may have an overall length L between about 10 mm and 65 mm, in one variation, pins  42 ,  62  may have an overall length L between about 10 mm and 35 mm and may be provided in a kit having, for example, 15 mm, 20 mm, 25 mm, and 30 mm lengths. Cannulas  44  may have diameters between about 4 mm and 8 mm, and may be provided in a kit having, for example, in 5 mm, 6 mm, and 7 mm diameters. 
     Referring again to  FIGS. 3-7 , according to one embodiment, cannulated tube  44  may comprise multiple pieces and include a distal end piece  72  having a. threaded exterior portion  74  movably connected to proximal cannula portion  76 . In this regard, threaded end piece  72  may be threadedly advanced into the pedicle such that cannula  44  may be semi-permanently docked in position with respect to a vertebral body to be treated. in general, threaded end piece  72  is configured and dimensioned to engage the pedicle in a similar manner to a pedicle screw, except the threaded end piece  72  is generally shorter than a pedicle screw and is cannulated to provide a portal into the interior portion of the vertebral body where the cancellous bone is generally located. Those skilled in the art of spine surgery and pedicle screw installation will be familiar with localizing the threaded end piece  72  into the pedicle. Distal piece  72  may be movably connected to proximal cannula  76  such that cannula  44  may angulate or rotate with respect to distal piece  72  while maintaining communication of the cannulation  45  between the distal piece  72  and proximal cannula  76 . According to one variation, any known flexible joint or linkage may be provided between end piece  72  and proximal cannula  76  to facilitate insertion and advancement of pins  42 ,  62  and/or an installation tool there through. 
     In operation, cannulated tube  44  may be positioned adjacent a pedicle using known techniques, including minimally invasive methods utilizing a K-wire (not shown). Once the distal piece  72  is docked in the pedicle, a user may move or wand the cannula  44  around as desired depending on the particular application. In this regard, a surgical user may achieve a variety of angles of approach to install one or more pins  42 ,  62 . In one variation, the interior portion of end piece  72  may have an hourglass profile to facilitate smooth transition of a pin through the distal piece  72  when cannula  44  is at an angle. In one variation, cannula  44  may move through a cone angle a of between about 30 to 60 degrees. In another embodiment, one or more openings  79  may be provided along the length of cannula  44  to facilitate angled entry of pins  42 ,  62  therethrough. 
     Pins  42 ,  62  described above may be used in any number of surgical methods and applications. Referring to  FIGS. 3-4 , according to one embodiment of a method according to the invention, one or more pins  42  of system  40  may be positioned at various angles into a collapsed vertebral body ( FIG. 3 ). In one variation, multiple pins  42  may be installed to decompress a vertebral fracture. The cannula  44  of system  40  may be deployed to access the vertebra through the pedicle to provide a working portal into the vertebral body. In one variation, distal end piece  72  of cannula extends through the cortical region of the vertebral body and into the cancellous region. Once such a working portal into the vertebral body is established, one or more pin introduction or pin skewering procedures may take place. 
     In one method according to the invention, one or more partially threaded pins  42  may be used to join together and/or compress one or more bone segments. For example, with a vertebral body fracture, pin  42  may be threaded through a first bone segment into a second bone segment. In this regard, the bone segments are generally brought into abutting contact to facilitate stitching and/or bone heating. Such a compressive feature may also be used for burst type fractures. In addition, or in the alternative, in another method according to the invention a first bone segment may be separated from another bone segment by displacing or pushing a pin  42  thereagainst. For a vertebral compression fracture, for example, one or more pins  42  may be used to push the compressed portion of the vertebral body in an outward direction and creating a vertical force that displaces the upper or tower end plates of the vertebral body. 
     Referring again to  FIGS. 3-4 , one exemplary embodiment vertebral compression fracture treatment is shown using a system  40 , One or more pins  42  may be inserted into a vertebral body at one ore more angles. Pins  42  may be threaded and or pushed into the bone portion to be treated through the aforesaid opening provided after installation of cannula  44 . Any variety or combination of partially threaded, fully threaded, or unthreaded pins may be installed to compress bone segments or portions and/or manipulate or reposition bone segments. Cannula  44  may be moved to alternative angles and one or more additional pins  42  may be installed within the vertebral cavity as described above until that expansion is complete and the bone treatment device may be fixated in the extended condition. In addition, the cannula  44  may then be disconnected from the distal end piece  72 , or in the alternative distal end piece  72  may be unthreaded and removed from the pedicle. Once installed, the pins  42  are generally configured. and dimensioned to stretch the vertebra substantially to its original dimension, as it were. 
     Referring to  FIGS. 8-9 , another method according to the invention is shown. According to one embodiment, a multitude of pins  62  may be sequentially inserted into a fractured vertebral body, as shown in  FIG. 8 , this regard, pins  62  function similar to a toothpick being inserted into a toothpick container as they are generally easily inserted in an insertion direction along an axis of cannula  44 . At the same time, as the volume of the vertebral body is filled, a vertical decompressive force is gradually transmitted to the end plates to force the end plates apart and decompress the compression fracture, as shown in  FIG. 9 . 
     Referring to  FIGS. 10-13 , another method or system  60  according to the invention is shown. According to one embodiment of system  60 , a plurality of modified pins  61  may be sequentially inserted into a fractured vertebral body, as shown in  FIGS. 10-11 . As best seen in  FIG. 12 , pins  61  are configured and dimensioned similar to pin  62  described above, except one or more grooves, troughs, or indentations  63  may extend transverse to longitudinal axis  64 . In this regard, pins  61  function similar to pins  62  and also facilitate cross stacking and scaffold formation when pins  61  are inserted at different angles into the vertebral body ( FIG. 13 ). For example, as shown in  FIGS. 10-11 , pins  61  may be inserted through a cannula  44  extending through both the left and right pedicles of a vertebral body. For example, a plurality of pins  61  may be inserted through the left pedicle into the vertebral body and are generally oriented in a first direction and one or more pins  61  may be inserted through the other pedicle to be generally oriented in a second direction angled with respect to the first direction. In one embodiment, pins  61  may be angled between about 45 and 135 degrees. As pins  61  inserted via, each pedicle are angled with respect to the pins inserted via the other pedicle, a grid or crossing pattern or scaffold structure may result as the pins  61  tend to orient or ride within the troughs or indentations  63  of the adjacent pins. At the same time, as the volume of the vertebral body is filled with pins  61 , a vertical decompressive force is gradually transmitted to the end plates to force the end plates apart and decompress the compression fracture, as shown in  FIG. 11 . Those skilled in the art may appreciate the vast customizability of such a system, as a surgeon practitioner may selectively install any number of pins  61  at any number of locations within the vertebral body. In addition, gradual and or precise controlled expansion of the vertebral body may be achieved as each individual pin  61  is installed. Moreover, as pins  61  tend to locate within indentations  63  controlled stacking and/or minimization of post insertion motion may be achieved. According to another embodiment, pins  61  may be used in combination with any other type of pins  42 ,  62 , described herein, whether partially threaded, completely threaded, or entirely nonthreaded, as desired. For example, a plurality of pins  61  may be inserted through one pedicle into the vertebral body and oriented in one general direction and one or more different types of pins  42 ,  62  may be inserted through the other pedicle to be oriented in a different direction. In still other embodiments, any combination of pins may be inserted via either or both pedicles. 
     According to one variation, indentations  63  may be positioned at varied transverse angles  65  with respect to axis  64 . Angle  65  may be between about 45 and 135 degrees. In one embodiment, when multiple indentations  63  are provided along the length of pin  61 , angles  65  may vary along the length of pin  61  such that indentations toward the center of pin  61  are positioned at a different angle  65  than indentations toward the ends. In this regard, when such indentation angles are used, a splayed pattern or matrix may be created which may have a more arcuate peripheral shape and be more conforming to the interior shape of a vertebral body. 
     The materials used in constructing system  40 , pins  42 ,  62 , and cannula  44  and the other devices described herein may comprise any of a wide variety of biocompatible materials. in certain embodiments, a radiopaque material, such as metal (e.g., stainless steel, titanium alloys, or cobalt alloys) or a polymer (e.g., ultra high molecular weight polyethylene) may be used, as is well know in the art, in alternate embodiments, a radiolucent material, such as polyetheretherketone (PEEK) may be used. When flowable or other filler material is desired, polymethylmethacrylate (PMMA) may be used In other alternate embodiments, a generally porous or microsphere material may be used as a filler material. Exemplary microsphere material that may be used is disclosed in U.S. patent application Ser. No. 11/552,244, filed Oct. 24, 2006 and entitled “Porous and Nonporous Materials for Tissue Grafting and Repair,” the entire contents of which are incorporated herein by reference. 
     Referring to  FIGS. 14-15 , another embodiment of a system  80  according to the invention is shown. System  80  is similar to system  40  described above, except shape memory alloy, such as nitinol may be used. Pins  82  are generally made from memory alloy that resumes a predefined shape when exposed to heat or other triggering methods. In this regard, pins  82  may have a first shape that is generally straight and a second shape that is generally curved. in one variation, when pins  82  are generally straight, the may have a shape or profile similar to pins  62  shown in  FIG. 7 . As with previously described embodiments, pins  82  may be forcibly advanced into an interior of a vertebral body through a minimally invasive technique such as through a working cannula  44  and packed into the interior of a vertebral body while straight and within the vertebral body the pins may resume their curved shape, as shown in  FIG. 15 , triggering expansion in the vertical direction to create a vertical or expansive force to thereby reduce a vertebral compression fracture and restore height to the vertebral body. Such an arch shape of pins  82  will occur when pins  82  are exposed to body temperature, returning the shape memory material to its memorized shape. 
     Referring to  FIGS. 16-17 , another embodiment of a bone fracture treatment system  90  is shown. System  90  generally comprises a plurality of flexible membranes or thin sheets  92  advanceable through cannula  44  into a vertebral body to be treated. In one embodiment, sheets  92  may be made from bone or other natural tissue. According to one embodiment, the sheet bone or tissue can have varied densities for forming a harder or softer filling. In another variation, sheets  92  may be made from a generally flexible yet resilient material, including, but not limited to, cloth, mesh any or other flexible elastic plastic or synthetic material, such as polyurethane. Any biocompatible material may also be used that has the ability to be inserted in a cannulated tube and inserted in the vertebral body. As best seen in  FIG. 17 , sheets  92  may be thin wafer like members that are flexible enough to be folded or curved to fit down a cannula, yet resilient enough to reform or spring back to a more straightened shape once inserted into the vertebral body. Sheets  92  may be packed or inserted into the interior of a vertebral body to facilitate and/or transfer lateral force or to expand in a vertical direction and create a vertical or expansive force to thereby reduce a vertebral compression fracture. As with previous embodiments, system  90  may be used in a minimally invasive procedure and in one embodiment sheets  92  may be fed down a tube or portal  44 , as shown in  FIG. 16 . In one variation sheets  92  may be fed using a plunger  94 . In one variation, plunger  94  may have a wire  95  with an umbrella like stopper  96  at a distal end thereof extending through a central hole  99  of sheets  92 . Plunger  94  may have a pusher portion  98  adjacent a proximal end to facilitate pushing or inserting sheets  92  through cannula  44  into the vertebral body. According to one variation, stopper  96  may be made from a biocompatible implantable material and stopper  96  may be detached or cut from plunger  94  to remain implanted in the body. 
     Referring to  FIGS. 18-19 , another embodiment of a bone treatment system or device  100  is shown. System  100  is similar to system  90  described above, except the membrane  102  may be integral with, connected to, or otherwise disposed about a central hub  104 . As with previous embodiments, system  100  may be used in a minimally invasive procedure and in one embodiment sheets  102  may be fed down a tube or portal  44 , as shown in  FIG. 18 . In this regard, as with prior embodiments, membrane  102  and hub  104  may be made from bone or other natural tissue or any other generally flexible yet resilient material, including, but not limited to, cloth, mesh any or other flexible elastic plastic or synthetic material, such as polyurethane. Any biocompatible material may also be used that has the ability to be inserted in a cannulated tube and inserted in the vertebral body. Central hub portion  104  has a general cylindrical shape and may facilitate radial expansion of membrane  102  once installed in a vertebral body. Membrane  102  may have a ring or cylindrical peripheral shape and/or be otherwise configured and dimensioned to radially enclose an area or central region  106  within bone. In this regard, the enclosed area may be filled with any known flowable material  108 , including but not limited to bone cement. In one variation, membrane  102  forms a. radial barrier preventing any flowable material to flow radially through membrane  102 . In another variation, when used to treat a vertebral compression fracture, membrane  102  may be radially expanded to abut or contact the inner walls of the cortical bone of a vertebral body. Openings may be provided adjacent the top and bottom to allow flowable material to contact the interior of the upper and lower endplate of the vertebral body being treated. According to one variation, a porous filler material, such as a microsphere material may be used. Exemplary microsphere material that may be used with system  100  is disclosed in U.S. patent application Ser. No. 11/552,244, filed Oct. 24, 2006 and entitled “Porous and Nonporous Materials for Tissue Grafting and Repair,” the entire contents of which are incorporated herein by reference. The device may be deployed or expanded within the vertebra by inserting or injecting a flowable material and/or a plurality of microsphere members to trigger expansion of device  1100  to create a radially constrained vertical or expansive force to thereby reduce a vertebral compression fracture. In certain embodiments, wall membrane  102  may be defined with a limited flexibility such that it may expand to enclose a maximum volume of the central region  106  and prevent overexpansion. In this regard, wall membrane  102  may be designed and configured to expand to conform to the interior volume of an intact healthy vertebral body of a particular patient as desired or diagnosed by a practitioner user. 
     Referring now to  FIGS. 20-21 , an alternative embodiment of a minimally invasive spine treatment system  120  is shown. System  120  is similar to system  90  described above, except it is adapted to be inserted or implanted in the disc space between adjacent vertebral bodies. System  120  generally comprises a plurality of flexible membranes or thin sheets  122  advanceable through cannula  44  into a disc space to be treated. Sheets  122  may be made from bone or other natural tissue or any other generally flexible yet resilient material, including, but not limited to, cloth, mesh any or other flexible elastic plastic or synthetic material, such as polyurethane. Any biocompatible material may also be used that has the ability to be inserted in a cannulated tube and inserted in the disc space. Sheets  122  may be thin wafer like members that are flexible enough to be folded or curved to fit down a cannula, yet resilient enough to reform or spring back to a more straightened shape once inserted into the disc space. In one variation, sheets  122  may be packed or inserted into the disc space to facilitate and/or transfer lateral force or to expand in a vertical direction and create a vertical or expansive force to thereby space apart adjacent vertebrae and/or decompress an adjacent nerve. As with previous embodiments, system  120  may be used in a minimally invasive procedure and in one embodiment sheets  122  may be fed down a tube or portal  44 , as shown in  FIG. 20 . In one variation sheets  122  may be fed using a plunger  124  similar to plunger  94 , described above, to facilitate pushing or inserting sheets  122  through cannula  44  into the disc space. 
     Referring now to  FIG. 22 , an alternative embodiment of a minimally invasive spine treatment system  130  is shown. System  130  is similar to system  100  described above, except it is adapted to be inserted or implanted in the disc space between adjacent vertebral bodies. Membrane  132  may be integral with, connected to, or otherwise disposed about a central hub  134 . Membrane  132  and hub  134  may be fed down a tube or portal  44  and, as with prior embodiments, membrane  132  and hub  134  may be made from bone or other natural tissue or any other generally flexible yet resilient material, including, but not limited to, cloth, mesh any or other flexible elastic plastic or synthetic material, such as polyurethane. Any biocompatible material may also be used that has the ability to be inserted in a cannulated tube and inserted in the disc space. Central hub portion  134  has a general cylindrical shape and may facilitate radial expansion of membrane  132  once installed in a disc space. Membrane  132  may have a ring or cylindrical peripheral shape and/or be otherwise configured and dimensioned to radially enclose an area or central region  136  within bone. In this regard, the enclosed area may be filled with any known flowable material  138 , including but not limited to bone cement. In one variation, membrane  132  forms a radial barrier preventing any flowable material to now radially through membrane  102 . Openings may be provided adjacent the top and bottom to allow flowable material to contact the upper and/or lower endplates of the adjacent vertebral bodies of the disc space being treated. According to one variation, a porous filler material, such as a microsphere material may be used. Exemplary microsphere material that may be used with system  100  is disclosed in U.S. patent application Ser. No. 11/552,244, filed Oct. 24, 2006 and entitled “Porous and Nonporous Materials for Tissue Grafting and Repair,” the entire contents of which are incorporated herein by reference. The device may be deployed or expanded within the disc space by inserting or injecting a flowable material and/or a plurality of microsphere members to trigger expansion of device  130  to create a radially constrained vertical or expansive force to thereby space apart adjacent vertebrae and/or decompress an adjacent nerve. In certain embodiments, wall membrane  132  may be defined with a limited flexibility such that it may expand to enclose a maximum volume of the central region  136  and prevent overexpansion. In this regard, wall membrane  132  may be designed and configured to expand to conform to the interior volume of an intact healthy vertebral disc of a particular patient as desired or diagnosed by a practitioner user. 
     While it is apparent that the invention disclosed herein is well calculated to fulfill the objects stated above, it will be appreciated that numerous modifications and embodiments may be devised by those skilled in the art.