US20080269759A1 - Systems and methods for treating bone using expandable bodies - Google Patents

Abstract

An expandable device is introduced into a cancellous bone volume of a vertebral body through a percutaneous access path. The vertebral body has at least one cortical plate that is depressed due to fracture. The expandable device is expanded while disposed within the cancellous bone volume. An expansion barrier placed in association with the expandable device directs expansion of the expandable device in a desired direction to move the fractured cortical plate toward a desired anatomic position.

Description

RELATED APPLICATIONS
• This application is a divisional of co-pending U.S. patent application Ser. No. 11/528,163, filed 27 Sep. 2006, and entitled “Systems and Methods for Removing Tissue from a Cancellous Bone Volume,” which is a divisional of U.S. patent application Ser. No. 10/958,600, filed 5 Oct., 2004, and entitled “Systems and Methods for Treating Fractured or Diseased Bone Using Expandable Bodies,” which is a divisional of U.S. patent application Ser. No. 09/754,451, filed 4 Jan. 2001 (now U.S. Pat. No. 6,899,719), which is a continuation of U.S. patent application Ser. No. 08/871,114, filed 9 Jun. 1997 (now U.S. Pat. No. 6,248,110), which is a continuation-in-part of U.S. patent application Ser. No. 08/659,678, filed Jun. 5, 1996 (now U.S. Pat. No. 5,827,289), which is a continuation-in-part of U.S. patent application Ser. No. 08/485,394, filed Jun. 7, 1995 (now abandoned), which is a continuation-in-part of U.S. patent application Ser. No. 08/188,224, filed Jan. 26, 1994 (now abandoned), each of which is incorporated herein by reference.
FIELD OF THE INVENTION
• The invention relates to the treatment of bone conditions in humans and other animals.
BACKGROUND OF THE INVENTION
• When cancellous bone becomes diseased, for example, because of osteoporosis, avascular necrosis, or cancer, the surrounding cortical bone becomes more prone to compression fracture or collapse. This is because the cancellous bone no longer provides interior support for the surrounding cortical bone.
• There are 2 million fractures each year in the United States, of which about 1.3 million are caused by osteoporosis alone. There are also other bone disease 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.
• U.S. Pat. Nos. 4,969,888 and 5,108,404 disclose apparatus and methods for the fixation of fractures or other conditions of human and other animal bone systems, both osteoporotic and non-osteoporotic. The apparatus and methods employ an expandable body to compress cancellous bone and provide an interior cavity. The cavity receives a filling material, which hardens and provides renewed interior structural support for cortical bone.
• The better and more efficacious treatment of bone disease that these patents promise can be more fully realized with improved systems and methods for making and deploying expandable bodies in bone.
SUMMARY OF THE INVENTION
• The invention provides improved systems and methods for treating bone, including vertebral bodies, as well as in other bone types, using one or more expandable bodies.
• One aspect of the invention provides a method. The method comprises the selection of a vertebral body for treatment. The vertebral body has a cortical wall enclosing a cancellous bone volume. The vertebral body also has at least one cortical plate that is depressed due to fracture. The method provides an expandable device including an expanded configuration and an unexpanded configuration. The method introduces the expandable device into the vertebral body through a percutaneous access path while in the unexpanded condition. The method expands the expandable device while disposed within the cancellous bone volume from the unexpanded configuration toward the expanded configuration, while providing an expansion barrier in association with the expandable device that directs expansion of the expandable device in a desired direction to move the fractured cortical plate toward a desired anatomic position.
• Another aspect of the invention provides a system comprising a tool defining a percutaneous access path into a vertebral body having a cortical wall enclosing a cancellous bone volume. The vertebral body also has at least one cortical plate that is depressed due to fracture. The system also includes an expandable device including an expanded configuration and an unexpanded configuration. The expandable device is sized and configured for introducing into the vertebral body through the percutaneous access path while in the unexpanded condition. The expandable device is also sized and configured to expand while disposed within the cancellous bone volume from the unexpanded configuration toward the expanded configuration. The system includes an expansion barrier sized and configured to be placed into association with the expandable device to directs expansion of the expandable device in a desired direction to move the fractured cortical plate toward a desired anatomic position. The system includes a tool for placing a volume of filling material within the cancellous bone volume.
• Another aspect of the invention provides a method comprising selecting a vertebral body for treatment, the vertebral body having a cortical wall enclosing a cancellous bone volume. The vertebral body also has at least one cortical plate that is depressed due to fracture. The method includes providing a first tool comprising an expandable device including an expanded configuration and an unexpanded configuration to move the fractured cortical plate toward a desired anatomic position. The method includes providing a second tool comprising an expansion barrier that directs expansion of the expandable device in a desired direction. The method includes introducing the first tool and second tool into the vertebral body through a percutaneous access path. The method includes placing the expansion barrier into association with the expandable device within the cancellous bone volume. The method includes expanding the expandable device from the unexpanded configuration toward the expanded configuration while the expansion barrier directs expansion of the expandable device in a desired direction to move the fractured cortical plate toward a desired anatomic position. The method includes placing a volume of filling material within the cortical bone volume.
• According to any of the various aspects of the invention, the filling material can comprise bone cement.
• According to any of the various aspects of the invention, the expandable device can expand by inflation and comprise, e.g., a balloon.
• 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
• FIG. 1 is a side view of the spinal column of a human;
• FIG. 2 is coronal view of a lumbar vertebra, partially cut away and in section, taken generally along line2-2 inFIG. 1;
• FIG. 3 is a vertical section of lumbar vertebrae;
• FIG. 4 is a plan view of a probe including a catheter tube carrying an expandable body intended to treat bone;
• FIGS. 5A to 5P are a series of coronal views of a vertebra, partially cut away and in section, showing the steps of introducing, via transpedicular access, an expandable body to compress cancellous bone and create a cavity within a vertebral body, and of then conveying a filling material into the cavity to restore interior integrity to cortical bone;
• FIG. 5Q is a lateral view, with parts broken away, of the vertebra shown in coronal view inFIG. 5P;
• FIG. 6 is a coronal view of a vertebral body in which an expandable body, restrained by an external sealing element, compresses cancellous bone to form a cavity;
• FIG. 7 is a coronal view, partially broken away and in section, of a vertebral body in which an expandable body is being collapsed after having formed a cavity, while an injector tip, also within the vertebral body, is simultaneously injecting filling material into the cavity;
• FIG. 8A is a coronal view of a vertebral body, partially broken away and in section, showing a tool that integrates an injector tube and an integral expandable body to create a cavity in cancellous bone, and also showing the injection of filling material simultaneous with collapse of the expandable body;
• FIG. 8B is a side view of the tool shown inFIG. 8A, located outside bone;
• FIG. 8C is sectional view of the tool shown inFIG. 8B, taken generally alongline8C-8C inFIG. 8B;
• FIG. 9 is a coronal view of a vertebral body showing multiple expandable bodies separately introduced by transpedicular approach;
• FIG. 10 is a view of the distal end of a probe in which two catheter tubes, each carrying an expandable body, are joined to form a symmetric array, when substantially expanded outside a bone;
• FIG. 11 is a view of the distal end of a probe in which two catheter tubes, each carrying an expandable body, are joined to form an asymmetric array, when substantially expanded outside a bone;
• FIG. 12 is a coronal view, partially broken away and in section, of a vertebral body into which multiple expandable bodies have been deployed by dual transpedicular access;
• FIG. 13 is a coronal view of a vertebral body, partially broken away and in section, into which multiple expandable bodies have been deployed by contralateral posterolateral access;
• FIG. 14 is a coronal view of a vertebral body, partially broken away and in section, in which multiple expandable bodies have formed multiple cavities which join to form a single cavity to receive filling material;
• FIG. 15 is a coronal view of a vertebral body, partially broken away and in section, in which multiple expandable bodies have formed multiple separate cavities to receive filling material;
• FIG. 16 is an anterior-posterior view of a region of the spine, showing multiple expandable bodies present within a targeted vertebral body using ipsilateral postereolateral access;
• FIG. 17 is an anterior-posterior view of a vertebral body, partially broken away and in section, in which multiple expandable bodies, introduced using ipsilateral postereolateral access, have formed multiple cavities which are joined to form a single cavity to receive filling material;
• FIG. 18 is an anterior-posterior view of a vertebral body, partially broken away and in section, in which multiple expandable bodies, introduced using an ipsa posterolateral access, have formed multiple separate cavities to receive filling material;
• FIG. 19 is a coronal view of a vertebral body, partially broken away and in section, in which multiple expandable bodies have been introduced by both transpedicular and posterolateral access;
• FIG. 20 is a perspective view of one representative embodiment of an expandable body having a stacked doughnut-shaped geometry;
• FIG. 21 is a view of another representative embodiment of an expandable body having an oblong-shaped geometry;
• FIG. 22 is an elevation view of another representative embodiment of an expandable body showing three stacked bodies and string-like restraints for limiting the expansion of the bodies during inflation;
• FIG. 23 is a perspective view of another representative embodiment of an expandable body having a kidney bean-shaped geometry;
• FIG. 24 is a top view of another representative embodiment of an expandable body having a kidney bean-shaped geometry with several compartments by a heating element or branding tool;
• FIG. 25 is a cross-sectional view taken along line25-25 ofFIG. 24;
• FIG. 26 is a perspective, lateral view of a vertebral body, partially broken away to show the presence of an expandable body, and also showing the major reference dimensions for the expandable body;
• FIG. 27 is a dorsal view of a representative expandable body having a humpback banana-shaped geometry in use in a right distal radius;
• FIG. 28 is a cross sectional view of the expandable body shown inFIG. 27, taken generally along line28-28 ofFIG. 27;
• FIG. 29A is a representative expandable body having a spherical shape with a base, located in a proximal humerus and viewed from the front (anterior) of the left proximal humerus;
• FIG. 29B is a representative expandable body having a cylindrical shape, located in a proximal humerus and viewed from the front (anterior) of the left proximal humerus;
• FIG. 30A is a representative embodiment of an expandable body located, as shown in a front (anterior) view of the proximal tibia, introduced beneath the medial tibial plateau;
• FIG. 30B is a side elevation view of the expandable body shown inFIG. 30A;
• FIG. 30C is a top perspective view of the expandable body shown inFIG. 30A, showing its generally cylindrical geometry;
• FIG. 31 is a top plan view of another representative embodiment of an expandable body for use in treating tibial plateau fractures, having a generally elliptical geometry;
• FIG. 32 is a side view of multiple expandable bodies stacked on atop another for use, for example, in treating tibial plateau fractures;
• FIG. 33 is another representative embodiment of an expandable body having an egg-shaped geometry located, as shown in a front (anterior) view of the proximal tibia, introduced beneath the medial tibial plateau;
• FIG. 34 is a representative embodiment of an expandable body having a spherical-shaped geometry for treating avascular necrosis of the head of the femur (or humerus), which is shown from the front (anterior) of the left hip;
• FIG. 35 is a side view of another representative embodiment of an expandable body having a hemispherically-shaped geometry for treating avascular necrosis of the head of the femur (or humerus);
• FIG. 36A is a view of a representative expandable body having a bent-geometry for preventing hip fracture, as seen from the front (anterior) of the left hip;
• FIG. 36B is a view of multiple expandable bodies individually deployed through multiple access points into the left hip for preventing hip fracture;
• FIG. 37A is a view of a representative expandable body having an asymmetric bow tie-shape for use in treating fracture of the calcaneus bone, shown in lateral view within the calcaneus;
• FIG. 37B is a perspective top view of the expandable body shown inFIG. 37A when substantially expanded outside the calcaneus;
• FIG. 38 shows a representative embodiment of an expandable body having a spherical or egg-shaped geometry shown in lateral view deployed within the calcaneus;
• FIGS. 39A to 39D show a multiple stage process of introducing filling material into a cavity formed by an expandable body in cancellous bone, to prevent or impede flow or seepage of filling material from the interior of the bone;
• FIG. 40 is an elevation view of an injector tip for filling material, over which a mesh is draped, which, when deployed in a cavity formed by an expandable body, impedes or prevents seepage of the material from the cavity;
• FIG. 41 is a coronal view of a vertebra, with parts broken away and in section, showing the deployment of the mesh shown inFIG. 40 within the vertebral body;
• FIGS. 42A to 42 C are schematic illustrations of a representative method and system for delivering a therapeutic substance to a bone using an expandable body;
• FIG. 43 is an illustration of the human skeleton, showing regions of long bone that can be treated using expandable bodies;
• FIG. 44 is a representative embodiment of multiple expandable bodies located, as shown in a front (anterior) view, within the proximal tibia, both introduced beneath the medial tibial plateau, one of the bodies being substantially expanded to form an interior barrier and serve as a platform for the other body, which is shown substantially collapsed;
• FIG. 45 is a front (anterior) view of the multiple expandable bodies, shown inFIG. 44, with both bodies in substantially expanded conditions to form a cavity within the proximal tibia beneath the medial tibial plateau;
• FIG. 46 is an enlarged front (anterior) perspective view of the multiple expandable bodies shown inFIG. 45, with the lower expandable body serving as a platform for the upper expandable body;
• FIG. 47 is diagrammatic view of a system for harvesting bone marrow in a bone-marrow producing bone using an expandable body;
• FIG. 48 is a section view of the catheter tube associated with the system shown inFIG. 48, taken generally along line48-48 ofFIG. 47; and
• FIG. 49 is an enlarged view of the expandable body associated with the system shown inFIG. 47 inside a bone for the purpose of harvesting bone marrow.
• 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
• This Specification describes new systems and methods to treat bones using expandable bodies. The use of expandable bodies to treat bones is disclosed in U.S. Pat. Nos. 4,969,888 and 5,108,404, which are incorporated herein by reference. Improvements in this regard are disclosed in U.S. patent application Ser. No. 08/188,224, filed Jan. 26, 1994; U.S. patent application Ser. No. 08/485,394, filed Jun. 7, 1995; and U.S. patent application Ser. No. 08/659,678, filed Jun. 5, 1996, which are each incorporated herein by reference.
• The new systems and methods will be first described with regard to the treatment of vertebra. It should be appreciated, however, the systems and methods so described are not limited in their application to vertebrae. As will be described in greater detail later, the systems and methods are applicable to the treatment of diverse bone types.
• I. Treatment of Vertebral Bodies
• AsFIG. 1 shows, the spinal column10 comprises a number of uniquely shaped bones, called thevertebrae12, asacrum14, and a coccyx16 (also called the tail bone). The number ofvertebrae12 that make up the spinal column10 depends upon the species of animal. In a human (whichFIG. 1 shows), there are twenty-fourvertebrae12, comprising sevencervical vertebrae18, twelvethoracic vertebrae20, and fivelumbar vertebrae22.
• When viewed from the side, asFIG. 1 shows, the spinal column10 forms an S-shaped curve. The curve serves to support the head, which is heavy. In four-footed animals, the curve of the spine is simpler.
• AsFIGS. 1 to 3 show, eachvertebra12 includes avertebral body26, which extends on the anterior (i.e., front or chest) side of thevertebra12. AsFIGS. 1 to 3 show, thevertebral body26 is in the shape of an oval disk. AsFIGS. 2 and 3 show, thevertebral body26 includes an exterior formed from compactcortical bone28. Thecortical bone28 encloses aninterior volume30 of reticulated cancellous, or spongy, bone32 (also called medullary bone or trabecular bone). A “cushion,” called anintervertebral disk34, is located between thevertebral bodies26.
• An opening, called thevertebral foramen36, is located on the posterior (i.e., back) side of eachvertebra12. Thespinal ganglion39 pass through theforamen36. Thespinal cord38 passes through thespinal canal37.
• Thevertebral arch40 surrounds thespinal canal37. Thepedicle42 of thevertebral arch40 adjoins thevertebral body26. Thespinous process44 extends from the posterior of thevertebral arch40, as do the left and right transverse processes46.
• A. Deployment of an Expandable Body
• FIG. 4 shows atool48 for preventing or treating compression fracture or collapse of a vertebral body using an expandable body.
• Thetool48 includes acatheter tube50 having a proximal and a distal end, respectively52 and54. Thedistal end54 carries anexpandable body56.
• Thebody56 includes anexterior wall58, which, inFIG. 4, is shown in a collapsed geometry. The collapsed geometry permits insertion of thebody56 into theinterior volume30 of a targetedvertebral body26.
• The insertion of thebody56 into theinterior volume30 of a targetedvertebral body26 can be accomplished in various ways.FIGS. 5A to 5Q show the insertion of thebody56 using a transpedicular approach, which can be performed either with a closed, mininimally invasive procedure or with an open procedure.
• In the described procedure, a patient lies on an operating table, while the physician introduces a conventionalspinal needle assembly60 into soft tissue in the patient's back. The patient can lie facedown on the table, or on either side, or at an oblique angle, depending upon the physician's preference. Indeed, the procedure can be performed through an open anterior procedure or an endoscopic anterior procedure, in which case thetool48 may be introduced from the anterior aspect of the vertebral body.
• Thespinal needle assembly60 comprises a stylet62 slidable housed within astylus64. Theassembly60 typically has, for example, about an 18 gauge diameter. Other gauge diameters can and will be used to accommodate appropriate guide pins, as will be described in greater detail later.
• Under radiologic, CT, or MRI monitoring, the physician advances theassembly60 through soft tissue (designated S inFIG. 5A) down to and into the targetedvertebra12, asFIG. 5A shows. The physician will typically administer a local anesthetic, for example, lidocaine, throughassembly60. In some cases, the physician may prefer other forms of anesthesia.
• The physician directs thespinal needle assembly60 to penetrate thecancellous bone32 of the targetedvertebra12. Preferably the depth of penetration is about 60% to 95% of thevertebral body26.
• FIG. 5A shows gaining access tocancellous bone32 through thepedicle42, which is called transpedicular access. However, posterolateral access, through the side of the vertebral body12 (designated P-L and shown in phantom lines inFIG. 5A), may be indicated, if a compression fracture has collapsed thevertebral body26 below the plane of thepedicle42, or for other reasons based upon the preference of the physician.
• After positioning thespinal needle assembly60 incancellous bone32, the physician holds thestylus64 and withdraws the stylet62 (seeFIG. 5B). Still holding thestylus64, the physician slides aguide pin66 through thestylus64 and into the cancellous bone32 (seeFIG. 5C). The physician now removes thestylus64, leaving theguide pin66 deployed within thecancellous bone32, asFIG. 5D shows.
• AsFIG. 5E shows, the physician makes a small incision (designated I inFIG. 5E) in the patient's back to accommodate atrocar68. The physician inserts thetrocar68 through the soft tissue S along theguide pin66 down to thepedicle42. The physician taps the distal end70 of thetrocar68 into thepedicle42 to secure its position.
• AsFIG. 5F shows, the physician next slides anouter guide sheath72 over thetrocar68. The distal end74 of theouter guide sheath72 is likewise tapped into thepedicle42. The physician removes thetrocar68, leaving theguide pin66 andouter guide sheath72 in place, asFIG. 5G shows. Alternatively, thetrocar68 and guidesheath72 can be introduced together in one step.
• AsFIG. 5H shows, the physician advances a drill bit76 (for example, 5 mm in diameter) over theguide pin66 through theouter guide sheath72. Under X-ray control (or using another external visualizing system), the physician operates thedrill bit76 to open apassage78 through thepedicle42 and into thecancellous bone32. The drilledpassage78 preferable extends no more than 95% across thevertebral body26.
• AsFIG. 5I shows, the physician removesdrill bit76 andguide pin66, leaving theouter guide sheath72. Thepassage78 made by thedrill bit76 remains, passing through thepedicle42 and into thecancellous bone32.
• As FIG.5J(1) shows, the physician next advances thecatheter tube50 andexpandable body56 through theouter guide sheath72 and into the drilledpassage78 in thecancellous bone32. As best shown in FIG.5J(2), thebody56 is maintained in a straightened, collapsed condition distally beyond the end of thecatheter tube50 during transport through theguide sheath72 and into the drilledpassage78 by a generally rigid, externalprotective sleeve73, which surrounds thebody56. Alternatively, an internal stiffening member (not shown) can extend within thebody56, to keep thebody56 in the desired distally straightened condition during passage through theguide sheath72. Once thebody56 is located in the desired location within thepassage78, the physician pulls thesleeve73 back, to uncover thebody56. Theexpandable body56 can be dipped into thrombin prior to its introduction into thevertebral body26 to facilitate in situ coagulation.
• The materials for thecatheter tube50 are selected to facilitate advancement of thebody56 into cancellous bone through theguide sheath72. Thecatheter tube50 can be constructed, for example, using standard flexible, medical grade plastic materials, like vinyl, nylon, polyethylenes, ionomer, polyurethane, and polyethylene tetraphthalate (PET). Thecatheter tube50 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.
• Once theprotective sheath73 is withdrawn, thewall58 of thebody56 is capable of assuming an expanded geometry within the interior volume30 (generally shown in FIG.5K(1)). To accommodate expansion of thebody56, thecatheter tube50 includes a first interior lumen80 (seeFIG. 4). Thelumen80 is coupled at the proximal end of thecatheter tube50 to a pressurized source offluid82. The fluid82 is preferably radio-opaque to facilitate visualization. For example, Renograffin™ can be used for this purpose.
• Thelumen80 conveys the fluid82 into thebody56 under pressure. As a result, thewall58 expands, as FIG.5K(1) shows. Because the fluid82 is radio-opaque, body expansion can be monitored fluoroscopically or under CT visualization. Using real time MRI, thebody56 may be filled with sterile water, saline solution, or sugar solution.
• Expansion of thewall58 enlarges thebody56 and compactscancellous bone32 within theinterior volume30. As FIG.5K(2) shows, the presence of thesheath73 serves to keep the proximal end of thebody56 away from edge-contact with the distal end of thecatheter tube50.
• The compaction ofcancellous bone32 forms acavity84 in theinterior volume30 of thevertebral body26. The compaction of cancellous bone also exerts interior force upon cortical bone, making it possible to elevate or push broken and compressed bone back to or near its original prefracture position. Using a single transpedicular access (as FIG.5K(1) shows), thecavity84 occupies about one-half of theinterior volume30. As will be described in greater detail later, using multiple accesses, e.g., one through each pedicle, acavity84 occupying substantially all of theinterior volume30 can be created.
• AsFIG. 4 shows, the proximal end of thecatheter tube50 is preferably coupled by tubing to a source ofnegative air pressure86. The negative pressure is conveyed through a secondinterior lumen81 to one or more suction holes88 on the distal end of thecatheter tube50. Prior to and during the expansion of thebody56, suction is applied to remove fats and other debris through the suction holes88 for disposal. A separate suction-irrigation tool can be deployed through theguide sheath72 for this purpose, if desired.
• Thebody56 is preferably left inflated for an appropriate waiting period, for example, three to five minutes, to allow coagulation inside thevertebral body26. After the appropriate waiting period, the physician collapses thebody56 and removes it through the outer guide sheath72 (seeFIG. 5L). To facilitate removal, the exterior surface of thebody56 can be treated, e.g., by ion beam-based surface treatment, to reduce friction during passage through theouter guide sheath72. AsFIG. 5L shows, upon removal of thebody56, the formedcavity84 remains in theinterior volume30.
• A suction-irrigation tool (not shown) can be introduced through theouter guide sheath72, to further flush and clear debris from the formedcavity84 after removal of thebody56.
• AsFIG. 5M shows, an injector nozzle ortip90, coupled by aninjector tube92 to aninjector gun94, is inserted through theouter guide sheath72 into the formedcavity84. Theinjector gun94 carries a fillingmaterial96. The fillingmaterial96 comprises, for example, methylmethacrylate cement or a synthetic bone substitute.
• Theinjector gun94 can comprise a cement gun made, for example, by Stryker Corporation (Kalamazoo, Mich.). Thisparticular injector gun94 has a manually operatedinjection grip98 with a mechanical advantage of about 9 to 1. Other injection guns may be used, having more or less mechanical advantage. Non-manually operated injection guns can also be used.
• Theinjector tip90 can be, for example, about 4.9 mm in diameter, to accommodate the flow a relativelyviscous material96 into thecavity84.
• AsFIG. 5M shows, theinjector gun94 pushes the fillingmaterial96 into thecavity84. While injecting thematerial96, the physician preferably begins with theinjector tip90 positioned at the anterior region of the cavity84 (asFIG. 5M shows). The physician progressively moves thetip90 toward the posterior region of the cavity84 (asFIG. 5N shows), away from the flow of the material96 as it enters and fills thecavity84. The physician observes the progress of the injection fluoroscopically.
• The physician can also check, using, for example, x-ray, for leakage of the material throughcortical bone28. Systems and methods for impeding or preventing such leakage will be described in greater detail later.
• The physician flowsmaterial96 into thecavity84, until thematerial96 reaches the distal end74 of the outer guide sheath72 (asFIG. 5O shows).
• Upon removing theinjector tube92 from theouter guide sheath72, the physician may, if necessary, tampresidual filling material96 from the distal end74 of theouter guide sheath72 into thecavity84. If fluoroscopic examination reveals void regions in thecavity84, the physician may again insert theinjector tube92 to addmore filling material96 into thecavity84.
• FIG. 7 shows an alternative technique for filling the cavity. In this technique, theinjector tip90 occupies thecavity84 while theexpandable body56 is collapsing within thecavity84. As thebody56 collapses, thetip90 injectsmaterial96 into the part of thecavity84 that the collapsingbody56 no longer occupies. The increasing volume of thecavity84 not occupied by the collapsingbody56 is thereby progressively filled by an increasing volume ofmaterial96. The presence of thebody56, partially expanded while thetip90 injects thematerial96, serves to compact and spread the injectedmaterial96 within thecavity84.
• As filling of thecavity84 progresses, preferably under fluoroscopic monitoring, the physician progressively retracts theinjector tip90 from the anterior region of thecavity84, toward theouter guide sheath72, allowing the material96 to progressively enter and fill thecavity84 with the collapse of thebody56.
• FIGS. 8A to 8C show a preferred embodiment of atool650 which integrates the injection tube and expandable body in a single structure. AsFIG. 8B shows, thetool650 includes acatheter tube652 having aproximal end654 and adistal end656. The distal end carries anexpandable body662.
• AsFIG. 8C shows, thecatheter tube652 has concentric inner and outer lumens, respectively658 and660. Theinner lumen658 communicates, byproximal tubing664, with aninjector gun94, of the type previously described. Theinner lumen658 also communicates with an injector nozzle ortip666 at the distalcatheter tube end656. Operation of thegun94 serves to inject fillingmaterial96 through the nozzle666 (asFIG. 8A shows).
• Theouter lumen660 communicates, viaproximal tubing668, with asource82 of pressurized liquid. Theouter lumen660 also communicates withports670 formed on the distalcatheter tube end656 underlying theexpandable body662. Operation of thesource82 serves to inject pressurized liquid into thebody662 to expand it, in the manner previously described.
• AsFIG. 8A shows, the physician introduces thetool650 into thecancellous bone32. The physician expands thebody662 to create thecavity84. Once thecavity84 is formed, the physician begins to collapse thebody662, while injecting the fillingmaterial96 through thenozzle666. The volume of thecavity84 occupied by the collapsingbody662 is progressively filled by the increasing volume of fillingmaterial96 injected through thenozzle666.
• As earlier described, the collapsingbody662 serves to compact and spread the fillingmaterial96 more uniformly within thecavity84. Under fluoroscopic monitoring, the physician progressively retracts thedistal end656 of thetool650 from the anterior region of thecavity84 toward theouter guide sheath72, allowing the material96 to enter and fill thecavity84.
• Upon filling thecavity84 with thematerial96, the physician removes theouter guide sheath72, asFIGS. 5P and 5Q show. The incision site is sutured or otherwise closed (designated by ST inFIG. 5P).
• In time, the fillingmaterial96 sets to a hardened condition within the cavity84 (seeFIGS. 5P and 5Q). Thehardened material96 provides renewed interior structural support for thecortical bone28.
• The above described procedure, carried out in a minimally invasive manner, can also be carried out using an open surgical procedure. Using open surgery, the physician can approach the bone to be treated as if the procedure is percutaneous, except that there is no skin and other tissues between the surgeon and the bone being treated. This keeps the cortical bone as intact as possible, and can provide more freedom in accessing theinterior volume30 of the vertebral body.
• B. Material Selection for the Expandable Body
• The material of thebody wall58 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 thebody wall58 is typically in the range of 2/1000ths to 25/1000ths of an inch, or other thicknesses that can withstand pressures of up to, for example, 250-500 psi.
• If desired, the material for thewall58 can be selected to exhibit generally elastic properties, like latex. Alternatively, the material can be selected to exhibit less elastic properties, like silicone. Usingexpandable bodies56 with generally elastic or generally semi-elastic properties, the physician monitors the expansion to assure that over-expansion and wall failure do not occur. Furthermore,expandable bodies56 with generally elastic or generally semi-elastic properties will require some form of external or internal restraints to assure proper deployment in bone.
• For example,expandable bodies56 with generally elastic properties will exhibit the tendency to backflow or creep into theouter guide sheath72 during their expansion. It is therefore necessary to internally or externally restrain abody56 that is subject to creeping, to keep it confined within the interior bone region. InFIG. 6, anexterior sealing element100 is provided for this purpose. InFIG. 6, the sealingelement100 takes the form of a movable o-ring.
• The physician advances the o-ring100 along thecatheter tube50 inside theguide sheath72 using a generally stiff stylet102 attached to the o-ring100. The physician locates the o-ring100 at or near thedistal end54 of thecatheter tube50 prior to conveying the liquid82 to expand thebody56. The o-ring100 is held in place by the generally stiff stylet102, which provides a counter force to prevent backward movement of the o-ring100 in theguide sheath72 as thebody56 expands. The o-ring100 thereby keeps all or a substantial portion of the generallyelastic body26 confined inside theinterior volume30. Thebody56 thereby serves to compact as much of thecancellous bone32 as possible.
• The use of anexternal sealing element100 to restrain theexpandable body56 may not be necessary when relatively inelastic materials are selected for thebody56. For example, the material for thebody wall58 can be selected to exhibit more inelastic properties, to limit expansion of thewall58 prior to wall failure. Thebody wall58 can also include one or more restraining materials, particularly when thebody wall58 is itself made from more elastic materials. The restraints, made from flexible, inelastic high tensile strength materials, limit expansion of thebody wall58 prior to wall failure. Representative examples of generally inelastic wall structures will be described in greater detail later.
• C. Selection of Shape and Size for the Expandable Body
• As will also be demonstrated later, when relatively inelastic materials are used for thebody wall58, or when thebody wall58 is otherwise externally restrained to limit its expansion prior to failure, a predetermined shape and size can be imparted to thebody56, when it is substantially expanded. The shape and size can be predetermined according to the shape and size of the surroundingcortical bone28 and adjacent internal structures, or by the size and shape of thecavity84 desired to be formed in thecancellous bone32.
• In one embodiment, which is generally applicable for treating bones experiencing or prone to fracture, the shape and size of thebody56′, when substantially expanded, can be designed to occupy at least about 30% of the volume ofcancellous bone32 in theinterior volume30. Abody56 having a substantially expanded size and shape in the range of about 40% to about 99% of the cancellous bone volume is preferred.
• In another embodiment, which is applicable for treating bones having more localized regions of fracture or collapse caused, for example, by avascular necrosis, the shape and size of thebody56 can be designed to occupy as little as about 10% of the cancellous bone volume. In this embodiment, the drilledpassage78 extends directly to the localized site of injury, to enable targeted introduction of thebody26.
• The shape of thecancellous bone32 to be compressed, and the presence of surrounding local anatomic structures that could be harmed if cortical bone were moved inappropriately, 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 thebody56 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 materials and geometry of thebody56 are selected to create acavity84 of desired size and shape incancellous bone32 without applying harmful pressure to the outercortical bone28 or surrounding anatomic structures.
• In some instances, it is desirable, when creating thecavity84, to move or displace thecortical bone28 to achieve the desired therapeutic result. Such movement is not per se harmful, as that term is used in this Specification, because it is indicated to achieve the desired therapeutic result. By definition, harm results when expansion of thebody56 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.
• D. Deployment of Multiple Expandable Bodies
• Formation of a desired cavity geometry incancellous bone32 using anexpandable body56 can be accomplished in diverse ways to achieve the desired therapeutic effect. The foregoing disclosure envisions the deployment of a singleexpandable body56 to compactcancellous bone32 and, by itself, form acavity84 having a desired shape and size to receive a fillingmaterial96.
• Alternatively, acavity84 having a desired shape and size incancellous bone32 can be formed by the deployment of more than oneexpandable body56 in a targeted region ofcancellous bone32, either sequentially or simultaneously.
• FIG. 9 shows the representative deployment of multipleexpandable bodies56A and56B through a singleouter guide sheath72, which is arranged to provide transpedicular access. It should be understood that deployment of multiple expandable bodies can likewise be achieved through anouter guide sheath72 arranged to provide a posterolateral access, through the side of the vertebral body26 (as shown as P-L in phantom lines inFIG. 9). InFIG. 9, theexpandable bodies56A and56B are carried byseparate catheter tubes50A and50B, which are not joined together.
• In the alternative embodiment shown inFIG. 10, a tool109 comprising anarray108 ofcatheter tubes50A and50B is provided. Eachcatheter tube50A and50B each carries anexpandable body56A and56B, which are shown inFIG. 10 in a collapsed condition. InFIG. 10, the distal ends of thecatheter tubes50A and50B are joined by aconnector106, for simultaneous deployment through anouter guide sheath72 into thevertebral body26, asFIG. 9 shows. As before described, a slidableprotective sheath73 encloses thebodies56A and56B during passage through theguide sheath72. Upon withdrawal of theprotective sheath73, expansion of thebodies56A and56B, either simultaneously or sequentially, creates acavity84. If desired, theconnector106 can permit relative adjustment of thecatheter tubes50A and50B, so that, when deployed, one expandable body is located more distal to another expandable body.
• For the sake of illustration,FIGS. 9 and 10 show twocatheter tubes50A and50B, but more than two catheter tubes can be deployed in thevertebral body26, either as separate tools (asFIG. 9 shows), or joined to form a composite array108 (asFIG. 10 shows).
• InFIG. 10, thebodies56A and56B of thearray108 have generally the same geometry, when substantially expanded, thereby providing a symmetric arrangement for compactingcancellous bone32. A generallysymmetric cavity84 results.
• Alternatively, as shown inFIG. 11, thebodies56A and56B possess different geometries when substantially expanded, thereby presenting an asymmetric arrangement for compactingcancellous bone32. A generallyasymmetric cavity84 results. By mutually adjusting catheter tubes through a connector106 (as previously described), the distal extensions of expandable bodies relative to each other can be made to differ, thereby also resulting in asymmetric cavity formation.
• The selection of size and shape of thearray108, whether symmetric or asymmetric, depends upon the size and shape of the targetedcortical bone28 and adjacent internal structures, or by the size and shape of thecavity84 desired to be formed in thecancellous bone32. The deployment of multipleexpandable bodies56 makes it possible to formcavities84 having diverse and complex geometries within bones of all types. Multiple expandable bodies having generally the same geometry can be deployed in different ways to create cavities of different geometries.
• It should be appreciated that the various styles of multipleexpandable bodies56 shown inFIGS. 9 to 11 are deployed in a distally straightened condition (asFIGS. 10 and 11 show) by using, e.g., a relatively stiff, surrounding sheath73 (shown in phantom lines inFIG. 10), which is manipulated in the same as previously described in connection with FIGS.5J(1) and5J(2). There are, of course, other ways to straighten thebodies56 for deployment into bone, such as through the use of internal stiffening elements.
• Access forexpandable bodies56 can be achieved through multiple access sites and in many different ways. For example, multiple expandable bodies can access the vertebral body from different regions of a targeted vertebra.
• FIG. 12 shows a representative dual transpedicular access, in which twoouter guide sheaths72A and72B are used to provide separate access for two or moreexpandable bodies56A and56B through different sides of thepedicle42A and42B of thevertebral body26.
• FIG. 13 shows a representative dual contra lateral posterolateral access, in which twoouter guide sheaths72A and72B are used to provide separate access for multipleexpandable bodies56A and56B from different lateral sides of thevertebral body26.
• Deployed from dual access sites as shown inFIGS. 12 and 13, the multipleexpandable bodies56A and56B each forms acavity84A and84B (shown inFIG. 14). Thecavities84A and84B are transversely spaced within thecancellous bone32. The transversely spacedcavities84A and84B may adjoin to form a single combined cavity (designated C inFIG. 14), into which the fillingmaterial96 is injected. Alternatively, asFIG. 15 shows, the transversely spacedcavities84A and84B may remain separated by a region of cancellous bone (designated by numeral110 inFIG. 13). In this arrangement, the fillingmaterial96 is injected into multiple,individual cavities84A and84B within the interior volume.
• As another example, multipleexpandable bodies56A and56B can access thevertebral body26 from the same general region of the vertebra.FIG. 16 shows a representative dual ipsilateral posterolateral access, in which twoouter guide sheaths72A and72B are used to provide separate access from the same lateral sides of thevertebral body26.
• Deployed from these access sites (seeFIG. 17), the multipleexpandable bodies56A and56B form vertically spaced, or stacked,cavities84A and84B. The vertically spacedcavities84A and84B may adjoin to form a single combined cavity (designated C inFIG. 17), into which the fillingmaterial96 is injected. Alternatively (seeFIG. 18), the vertically spacedcavities84A and84B may be separated by a region of cancellous bone (designated by numeral110 inFIG. 18), forming multipleindividual cavities84A and84B within the interior volume, each of which is individually filled with a fillingmaterial96A and96B.
• By way of another example,FIG. 19 shows a firstouter guide sheath72A arranged to provide a transpedicular access and a secondouter guide sheath72B to provide a posterolateral access.
• Systems for treating bone using multiple expandable bodies can include directions79 (seeFIG. 12) for deploying the first and second expandable bodies. For example, thedirections79 can instruct the physician to insert a first expandable body into the interior volume through a first access path through cortical bone, while inserting a second expandable body into the interior volume through a second access path through cortical bone different than the first access path.
• In any of the above-described examples, eachguide sheath72A or72B can itself accommodate a single expandable body or multiple expandable bodies. The size and shape of the bodies may be the same, or they may vary, according to the desired objectives of the physician for the targeted vertebral body.
• E. Representative Embodiments of Expandable Bodies to Treat Vertebrae
• i. Constrained Donut-Shaped Geometries
• FIG. 20 shows a representative embodiment of an expandable body, which is broadly denoted by the numeral210. Thebody210 comprises a pair of hollow, inflatable,non-expandable parts212 and214 of flexible material, such as PET or Kevlar.Parts12 and14 have asuction tube216 therebetween for drawing fats and other debris by suction intotube216 for transfer to a remote disposal location. Thecatheter tube216 has one or more suction holes so that suction may be applied to the open end oftube216 from a suction source (not shown).
• Theparts212 and214 are connected together by an adhesive which can be of any suitable type.Parts212 and214 are doughnut-shaped, as shown inFIG. 20 and havetubes218 and220 which communicate with and extend away from theparts212 and214, respectively, to a source of inflating liquid under pressure (not shown). The liquid expands thebody210 as already described.
• FIG. 21 shows a modifieddoughnut shape body280 of the type shown inFIG. 20, except the doughnut shapes ofbody280 are not stitched onto one another. InFIG. 21,body280 has a pear-shaped outerconvex surface282 which is made up of a firsthollow part284 and a secondhollow part285. Atube288 is provided for directing liquid into the two parts alongbranches290 and292 to inflate the parts after the parts have been inserted into the interior volume of a bone. Acatheter tube216 may or may not be inserted into thespace296 between two parts of theballoon280 to provide irrigation or suction. An adhesive bonds the twoparts284 and285 together.
• FIG. 22 shows another representative embodiment of an expandable body, designated309. Thebody309 has a generally round geometry and threeexpandable body units310,312 and314. Thebody units310,312, and314 include string-likeexternal restraints317, which limit the expansion of thebody units310,312, and314 in a direction transverse to the longitudinal axes of thebody units310,312, and314. Therestraints317 are made of the same or similar material as that of thebody units310,312, and314, so that they have some resilience but substantially no expansion capability.
• Atubes315 direct liquid under pressure into thebody units310,312 and314 to expand the units and cause compaction of cancellous bone. Therestraints317 limit expansion of the body units prior to failure, keeping theopposed sides377 and379 substantially flat and parallel with each other.
• ii. Constrained Kidney-Shaped Geometries
• FIG. 23 shows another representative embodiment of anexpandable body230, which has a kidney-shaped geometry. Thebody230 has a pair of opposed kidney-shapedside walls232 and acontinuous end wall234. Atube238 directs liquid into the body to expand it within the vertebral body.
• FIG. 24 shows another representative embodiment of anexpandable body242, which also has a kidney-shaped geometry. Thebody242 is initially a single chamber bladder, but the bladder is branded along curved lines or strips241 to formattachment lines244 which take the shape of side-by-side compartments246 which are kidney shaped as shown inFIG. 25. A similar pattern of strips as in240 but in straight lines would be applied to a body that is square or rectangular. The branding causes a welding of the two sides of the bladder to occur.
• The details of these and other expandable bodies usable to treat vertebral bodies are described in U.S. patent application Ser. No. 08/188,224, filed Jan. 26, 1994, which is incorporated herein by reference.
• F. Selection of Desired Geometry
• The eventual selection of the size and shape of a particular expandable body or bodies to treat a targetedvertebral body26 is based upon several factors. When multiple expandable bodies are used, the total combined dimensions of all expandable bodies deployed, when substantially expanded, should be taken into account.
• The anterior-posterior (A-P) dimension (seeFIG. 26) for the expandable body or bodies is selected from the CT scan or plain film or x-ray views of the targetedvertebral body26. The A-P dimension is measured from the internal cortical wall of the anterior cortex to the internal cortical wall of the posterior cortex of the vertebral body. In general, the appropriate A-P dimension for the expandable body or bodies is less than this anatomic measurement.
• The appropriate side to side dimension L (seeFIG. 26) for an expandable body or bodies is also selected from the CT scan, or from a plain film or x-ray view of the targeted vertebral body. The side to side distance is measured between the internal cortical walls laterally across the targeted vertebral body. In general, the appropriate side to side dimension L for the expandable body is less than this anatomic measurement.
• The lumbar vertebral body tends to be much wider in side to side dimension L then in A-P dimension. In thoracic vertebral bodies, the side to side dimension and the A-P dimensions are almost equal.
• The height dimensions H of the expandable body or bodies (seeFIG. 26) is chosen by the CT scan or x-ray views of the vertebral bodies above and below the vertebral body to be treated. The height of the vertebral bodies above and below the vertebral body to be treated are measured and averaged. This average is used to determine the appropriate height dimension of the chosen expandable body.
• The dimensions of expandable body or bodies for use in vertebrae are patient specific and will vary across a broad range, as summarized in the following table:

• 		Posterior	Side to Side
  	Height (H)	(A-P)	Dimension
  	Dimension	Dimension	(L) of
  	of Typical	of Typical	Typical
  Vertebra	Expandable	Expandable	Expandable
  Type	Body or Bodies	Body or Bodies	Body or Bodies
  Lumbar	0.5 cm to	0.5 cm to	0.5 cm to
  	4.0 cm	4.0 cm	5.0 cm
  Thoracic	0.5 cm to	0.5 cm to	0.5 cm to
  	3.5 cm	3.5 cm	4.0 cm

• A preferredexpandable body56 for use in a vertebral body is stacked with two or more expandable members of unequal height (seeFIG. 26), where each member can be separately inflated through independent tube systems. The total height of the stack when fully inflated should be within the height ranges specified above. Such a design allows the fractured vertebral body to be returned to its original height in steps, which can be easier on the surrounding tissue, and it also allows the same balloon to be used in a wider range of vertebral body sizes.
• II. Treatment of Long Bones
• Like vertebrae, the interior regions of long bones substantially occupied by cancellous bone can be treated with the use of one or more expandable bodies.FIG. 43 shows representative regions of thehuman skeleton600, where cancellous bone regions of long bones can be treated using expandable bodies. The regions include the distal radius (Region602); the proximal tibial plateau (Region604); the proximal humerus (Region606); the proximal femoral head (Region608); and the calcaneus (Region610).
• As for vertebral bodies, expandable bodies possess the important attribute of being able, in the course of forming cavities by compressing cancellous bone, to also elevate or push broken or compressed cortical bone back to or near its normal anatomic position. This is a particularly important attribute for the successful treatment of compression fractures or cancellous bone fractures in the appendicular skeleton, such as the distal radius, the proximal humerus, the tibial plateau, the femoral head, hip, and calcaneus.
• Representative examples of expandable bodies for the treatment of cancellous bone regions of long bones will be next described.
• A. Expandable Body for the Distal Radius
• The selection of an appropriate expandable to treat a fracture of the distal radius (Region602 inFIG. 43) will depend on the radiological size of the distal radius and the location of the fracture.
• FIGS. 27 and 28 show a representativeexpandable body260 for use in the distal radius. Thebody260, which is shown deployed in thedistal radius252, has a shape which approximates a pyramid but more closely can be considered the shape of a humpbacked banana. The geometry of thebody260 substantially fills the interior of the space of the distal radius to compactcancellous bone254 against theinner surface256 ofcortical bone258.
• Thebody260 has a lower,conical portion259 which extends downwardly into the hollow space of thedistal radius252. Thisconical portion259 increases in cross section as a centraldistal portion261 is approached. The cross section of thebody260 is shown at a central location (FIG. 27), which is near the widest location of thebody260. The upper end of thebody260, denoted by the numeral262, converges to thecatheter tube288 for directing a liquid into thebody260 to expand it and force the cancellous bone against the inner surface of the cortical bone.
• The shape of thebody260 is determined and restrained by tufts formed bystring restraints265. These restraints are optional and provide additional strength to thebody260, but are not required to achieve the desired configuration.
• Thebody260 is placed into and taken out of the distal radius in the same manner as that described above with respect to the vertebral bone.
• Typical dimensions of the distal radius body vary as follows:
• The proximal end of the body260 (i.e. the part nearest the elbow) is cylindrical in shape and will vary from 0.4×0.4 cm to 1.8×1.8 cm.
• The length of the distal radius body will vary from 1.0 cm to 12.0 cm.
• The widest medial to lateral dimension of the distal radius body, which occurs at or near the distal radio-ulnar joint, will measure from 0.5 cm to 2.5 cm.
• The distal anterior-posterior dimension of the distal radius body will vary from 0.4 to 3.0 cm.
• B. Expandable Body for Proximal Humerus Fracture
• The selection of an appropriateexpandable body266 to treat a given proximal humeral fracture (Region606 inFIG. 43) depends on the radiologic size of the proximal humerus and the location of the fracture.
• FIG. 29A shows a representative embodiment of anexpandable body266 for use in theproximal humerus269. Thebody266 is spherical for compacting thecancellous bone268 in aproximal humerus269. If surrounding cortical bone has experienced depression fracture, expansion of thebody266 also serves to elevate or move the fractured cortical bone back to or near its anatomic position before fracture.
• Amesh270, embedded or laminated and/or winding, may be used to form aneck272 on thebody266. A second mesh270amay be used to conform the bottom of the base272ato the shape of the inner cortical wall at the start of the shaft. These mesh restraints provide additional strength to thebody266, but the configuration can be achieved through molding of the body.
• Thebody266 has acatheter tube277 into which liquid under pressure is forced into the body to expand it to compact the cancellous bone in the proximal humerus. Thebody266 is inserted into and taken out of the proximal humerus in the same manner as that described above with respect to the vertebral bone.
• Typical dimensions of theexpandable body266 shown inFIG. 29A for proximal humerus fracture vary as follows:
• The spherical end of the body will vary from 0.6×0.6 cm to 3.0×3.0 cm.
• The neck of the proximal humeral fracture body will vary from 0.5×0.5 cm to 3.0×3.0 cm.
• The width of the base portion or distal portion of the proximal numeral fracture body will vary from 0.5×0.5 cm to 2.5×2.5 cm.
• The length of the body will vary from 3.0 cm to 14.0 cm.
• FIG. 29B shows another representative embodiment of anexpandable body266′ for use in theproximal humerus269. Instead of being spherical, thebody266′ shown inFIG. 29B has a generally cylindrical geometry for compacting thecancellous bone268 in aproximal humerus269. Alternatively, thecylindrical body266′ can be elongated to form an elliptical or football-shaped geometry. Typical dimensions for a cylindrical or elliptical body vary from 0.6 cm to 3.0 cm in diameter to 3.0 cm to 14.0 cm in length.
• C. Expandable Body for Proximal Tibial Plateau Fracture
• The selection of an expandable body to treat a given tibial plateau fracture (Region604 inFIG. 43) will depend on the radiological size of the proximal tibial and the location of the fracture.
• FIG. 30A shows a representativeexpandable body280 for treating a tibial plateau fracture. Thebody280 may be introduced into the tibia from any direction, as desired by the physician, for example, from the top, or medial, lateral, anterior, posterior, or oblique approach. InFIG. 30A, thebody280 has been introduced intocancellous bone284 from the anterior side of thetibia283 and is shown position in oneside282 of thetibia283.
• Thebody280, when substantially inflated (asFIG. 30A shows), compacts the cancellous bone in thelayer284 surrounding thebody280. If the tibia plateau has experienced depression fracture, expansion of thebody280 also serves to move the tibia plateau back to or near its anatomic elevation before fracture, asFIG. 30A shows. Fractures on both the medial and lateral sides of the tibia can be treated in this manner.
• AsFIG. 30B shows, thebody280 has a pair ofopposed sides285 and287. Thesides285 and287 are interconnected byrestraints288, which pass through thebody280.FIG. 30C shows the tied-off ends291 of therestraints288.
• Therestraints288 can be in the form of strings or flexible members of any suitable construction. Therestraints288 limit expansion of thebody280 prior to failure. Therestraints288 make thesides285 and287, when thebody280 is substantially expanded, substantially parallel with each other and, thereby, non-spherical.
• Atube290 is coupled to thebody280 to direct liquid into and out of the body to expand it. The body is inserted into and taken out of the tibia in the same manner as that described above with respect to the vertebral bone.FIG. 30C shows a substantially circular configuration for thebody280, although thebody280 can also be substantially elliptical, asFIG. 31 shows.
• Other geometries and configurations can also be used. For example, asFIG. 32 shows, two or more expandable bodies280(1),280(2), and280(3) can be stacked one atop another to produce a different cavity geometry and to enhance plateau fracture displacement. The multiple bodies280(1),280(2), and280(3) can comprise separate units or be joined together for common deployment. When deployed as separate units, the bodies280(1),280(2), and280(3) can enter through the same access point or from different access points.
• As another example, asFIG. 33 shows, thebody280′ can assume an egg shape when substantially inflated, to form a cavity and reshape broken bones. Other geometries, such as cylindrical or spherical, can also be used for the same purpose. Typical dimensions of thebody280 for treating proximal tibial plateau fracture vary as follows:
• The thickness or height of the body will vary from 0.3 cm to 5.0 cm.
• The anterior-posterior (front to back) dimension will vary from 1.0 cm to 6.0 cm.
• The medial to lateral (side-to-side) dimension will vary from 1.0 cm to 6.0 cm.
• FIGS. 44 and 45 show multipleexpandable zones614 and616 deployed incancellous bone620. Onezone614 serves as a platform to confine and direct the expansion of theother zone616. For the purpose of illustration,FIGS. 44 and 45 show themultiple zones614 and616 used for this purpose to treat atibial plateau fracture622.
• In the embodiment shown inFIGS. 44 and 45, thezones614 and616 comprise separate expandable bodies. It should be appreciated, however, that thezone614 and616 can comprise parts of a single expandable body.
• In the illustrated embodiment (asFIG. 44 shows), the firstexpandable body614 is deployed through a first outer guide sheath618(1) intocancellous bone620 below thefracture622. AsFIG. 44 shows, when substantially expanded, thefirst body614 expands more along its horizontal axis624 (i.e., in a side-to-side direction) than along its vertical axis626 (i.e., in a top-to-bottom direction). The greater expanded side-to-side geometry of thefirst body614 compacts cancellous bone in a relatively thin region, which extends substantially across theinterior volume628 occupied by thefirst body614. The geometric limits of thebody614 will typically fall just inside the inner cortical walls of the proximal tibia, or whatever bone in which thefirst body614 is deployed.
• The expandedfirst body614 creates abarrier630 within theinterior region628. Due to the less expanded top-to-bottom geometry of thefirst body614, a substantiallyuncompacted region632 of cancellous bone is left above thebody614, which extends from the formedbarrier630 upward to thefracture622. In a representative deployment, theuncompacted region632 extends about 2 cm below thetibial plateau fracture622.
• AsFIG. 44 shows, a secondexpandable body616 is deployed through a second outer guide sheath618(2) into theuncompacted region632 left between thefirst body614, when substantially expanded, and the targetedtibial plateau fracture622.
• AsFIG. 45 shows, the secondexpandable body616 has a geometry, substantially like that shown inFIGS. 30A to 30C. When substantially inflated, thesecond body616 compacts a large percentage of the cancellous bone in theregion632 above the firstexpandable body614. The presence of thebarrier630, which the expandedfirst body614 creates (seeFIG. 46 also), prevents expansion of thesecond body616 in a direction away from thetibial platform fracture622. Instead, thebarrier630 directs expansion of thesecond body616 toward thefracture622. Buttressed by thebarrier630, the expansion of thebody616 is directed against the fracturedplateau622, restoring it to its normal anatomic position, asFIGS. 45 and 46 show.
• It should be appreciated that one or more expandable bodies can be used as platforms or barriers to direct the expansion of one or more other expandable bodies in other localized interior bone regions. The barrier makes possible localized cavity formation in interior bone regions. Use of the barrier preserves healthy regions of cancellous bone, while directing the main compacting body toward localized fractures or localized regions of diseased cancellous bone.
• D. Expandable Body for Femoral Head
• The size of an expandable body for use in the femoral head (Region608 inFIG. 43) is chosen based upon the radiological or CT scan size of the head of the femur and the location and size of the avascular necrotic bone.
• FIG. 34 shows a representative embodiment of anexpandable body300 introduced inside thecortical bone302 of the femoral head. AsFIG. 34 shows, the femoral head is thin at theouter end304 of the femur and increases in thickness at thelower end306 of the femur. Atube309 directs liquid to expand thebody300. Thetube309 extends along the femoral neck and into the femoral head. Theexpandable body300 compacts thecancellous bone307 in this bone region, while also moving fractured cortical bone back to or near its normal anatomic position.
• The femoral head is generally spherical in configuration, and thebody300 can have either a hemispherical (seeFIG. 35) as well as spherical geometry (asFIG. 34 shows). The hemispherical shape is maintained inFIG. 34 by bonding overlapping portions of thebody300, creatingpleats300b.
• Thebody300 is inserted into and taken out of the femoral head in the same manner as that described with respect to the vertebral bone.
• Typical dimensions of an expandable body for use in treating the femoral head vary as follows:
• The diameter of the expandable body will vary from 0.5 cm to up to 4.5 cm. The dimensions of the hemispherical body (FIG. 35) are the same as the those of the spherical body (FIG. 34), except that approximately one half is provided.
• E. Expandable Body for Prevention of Hip Fracture
• Patients with bone density in the hip (Region612 inFIG. 43) below a threshold value are at increased risk of hip fracture, and lower densities create greater risk. Patient selection is done through a bone density scan.
• FIG. 36A shows a representative embodiment of anexpandable body410 having a “boomerang” geometry for use in preventing hip fracture. When substantially expanded (asFIG. 36A shows), thebody410 forms a cylinder, which gradually bends in the middle, like a boomerang, and extends from about 0.5 cm from the end of thefemoral head411 through thefemoral neck412 and down into the proximalfemoral diaphysis413 about 5 to 7 cm past thelesser trochanter414.
• Expansion of thebody410 is limited to achieve the described geometry byrings430 of inelastic material. Therings430 are held in a spaced apart relationship along one side of thebody410 by attachment to aninelastic band416, which runs the length of that side ofbody410. Therings430 are held in a farther spaced apart relationship along the opposite side of thebody410 by attachment to another, longerinelastic band417, which runs the length of the opposite side of thebody410. Atube419 conveys liquid to inflate thebody410.
• Prior to deployment within the body, thebody410 is collapsed and rolled up and held against theinflation tube419 using, for example, with frangible connectors that will break as the body is subject to expansion. To deploy thebody410 into the hip, the surgeon uses a power drill under radiographic guidance to create acavity420, which is, for example, about 4 to 6 mm wide starting at the lateralfemoral cortex421 and proceeding into thefemoral head411. Thebody410 is deployed through aguide sheath423, following thecavity420. Thebody410 is deployed, prior to expansion, facing thelesser trochanter414, so that expansion occurs toward thefemoral diaphysis413, and not toward the greatertrochanteric region422.
• The expansion of thebody410 is guided by therings430 andbands416 and417, which cause bending of thebody410 downward into thelesser trochanter414. Optionally, a second cavity can be drilled down into thediaphysis413, starting from the same entry point or from the other side.
• The body length is chosen by the physician to extend about 0.5 cm from the end of the femoral head, through the femoral neck and into the proximal femoral diaphysis, usually about 4 to 8 cm below the lesser trochanter. The body diameter is chosen by measuring the inner cortical diameter of the femoral neck (the most narrow area) and subtracting 0.5 cm. The preferred dimensions of thebody410 are a total length of 10-20 cm and a diameter of about 1.0-2.5 cm.
• Patients having the lowest bone densities in the femoral head may require greater compacting in the femoral head, which may, for example, be provided by using two bodies, one after the other: thebent body410 followed by the femoral head body (inserted at the same point and expanded prior to inserting any supporting material). Alternatively, thebent body410 may be adapted to have a distal portion that approximates the shape of the femoral head body.
• The geometry of the single,restrained body410 can be approximated by multiple expandable bodies deployed separately, or coupled together, or stacked together.FIG. 36B shows a representative embodiment of the use of multiple expandable bodies in the hip region.
• AsFIG. 36B shows, a first expandable body410(1) is introduced through a first outer guide sheath423(1) in the proximal lateral cortex of the femoral shaft. The first body419(1) is deployed across thefemoral neck480 into thefemoral head482.
• A second expandable body410(2) is introduced through a second outer guide sheath423(2) in thegreater trochanter422 of the femur. The first body419(1) is deployed in the direction of thefemoral diaphysis413.
• Other approaches can be used. For example, one body can be introduced through thefemoral neck480, and the other body can be introduced along the shaft of the femur.
• One or both of the bodies410(1) and410(2) can include external restraints to limit expansion, in the manner described with regard to thebody410. Expansion of the bodies410(1) and410(2) compacts cancellous bone to form a cavity having a geometry approximating that formed by thesingle body410.
• F. Expandable Body for Calcaneus Fracture
• The size of an expandable body for use in treating fracture of the calcaneus (heel bone) (Region610 inFIG. 43) is chosen based upon the radiological or CT scan size of the calcaneus and the location and size of the fracture.
• FIGS. 37A and 37B show a representativeexpandable body450 for treating fracture of thecalcaneus452. Atube464 conveys liquid into thebody450 to expand it.
• InFIG. 37A, thebody450 is deploy into thecalcaneus452 by a posterior approach, through the tuberosity. Other approaches can be used, as desired by the physician. A power drill opens apassage466 through the tuberosity into the calcaneus. Anouter guide sheath470 is positioned within thepassage466, abutting the posterior of the calcaneus, in the manner previously described in obtaining access to a vertebral body. Thebody450 is introduced through theguide sheath470 and formedpassage466 into the calcaneus.
• Expansion of thebody450 is limited within the confines of the calcaneus by inelastic peripheral bands454 (seeFIG. 37B). Thebands454 constrain expansion of thebody450 to an asymmetric, pear-shaped geometry, best shown inFIG. 37B. The pear-shaped geometry has a major dimension H1 occupying the region of theposterior facet454. The major dimension H1 is located here, because the part of the calcaneus most likely to require elevation and realignment during expansion of thebody450 is the depressed part of theposterior facet454 of the calcaneus, where theposterior facet454 abuts thetalus456.
• The pear-shaped geometry has a smaller, minor dimension occupying the region of theanterior facet458 of the calcaneus, near the calcaneal-cuboid joint460, between the calcaneus and cuboid bone462.
• Expansion of thebody410 compactscancellous bone470 within thecalcaneus452. The expansion also lifts a depression fracture of theposterior facet454 back to or near its original anatomic elevation adjacent thetalus456. When collapsed and removed, thebody410 leaves a cavity in cancellous bone into which filling material can be introduced in the manner previously described.
• FIG. 38 shows another representative embodiment of anexpandable body450′ for use in treating fractures in the calcaneus. Thebody450′ inFIG. 38 has a more spherical or egg-shaped geometry than the pear-shapedbody450 shown inFIG. 37B. Like the pear-shapedbody450, thebody450′, when expanded within the calcaneus, forms a cavity within cancellous bone and realigns fractured cortical bone at or near its normal anatomic position.
• III. Selection of Other Expandable Bodies (Further Overview)
• Different sizes and/or shapes of expandable bodies may be used at sites not specified above, such as the jaw bones, the midshaft of the arm and leg bones, the cervical vertebral bodies, the foot and ankle bones, the pelvis, the ribs, and the like.
• The choice of the shape and size of a expandable body takes into account the morphology and geometry of the site to be treated. As before stated, the shape of the cancellous bone to be compressed, and the local structures that could be harmed if bone were moved inappropriately, are generally understood by medical professionals using textbooks of human skeletal anatomy along with their knowledge of the site and its disease or injury. Precise dimensions for a given patient can be further determined by X-ray of the site to be treated.
• As one general guideline, the selection of the geometry of the expandable body should take into account that at least 40% of the cancellous bone volume needs to be compacted in cases where the bone disease causing fracture (or the risk of fracture) is the loss of cancellous bone mass (as in osteoporosis). The preferred range is about 30% to 90% of the cancellous bone volume. Compacting less of the cancellous bone volume can leave too much of the diseased cancellous bone at the treated site. The diseased cancellous bone remains weak and can later collapse, causing fracture, despite treatment.
• Another general guideline for the selection of the geometry of the expandable body is the amount that the targeted fractured bone region has been displaced or depressed. The expansion of the body within the cancellous bone region inside a bone can elevate or push the fractured cortical wall back to or near its anatomic position occupied before fracture occurred.
• However, there are times when a lesser amount of cancellous bone compaction is indicated. For example, when the bone disease being treated is localized, such as in avascular necrosis, or where local loss of blood supply is killing bone in a limited area, the expandable body can compact a smaller volume. This is because the diseased area requiring treatment is smaller.
• Another exception lies in the use of an expandable body to improve insertion of solid materials in defined shapes, like hydroxyapatite and components in total joint replacement. In these cases, the body shape and size is defined by the shape and size of the material being inserted.
• Yet another exception is the delivery of therapeutic substances, which will be described in greater detail later. In this case, the cancellous bone may or may not be diseased or adversely affected. Healthy cancellous bone can be sacrificed by significant compaction to improve the delivery of a drug or growth factor which has an important therapeutic purpose. In this application, the size of the expandable body is chosen by the desired amount of therapeutic substance sought to be delivered. In this case, the bone with the drug inside is supported while the drug works, and the bone heals through exterior casting or current interior or exterior fixation devices.
• Generally speaking, providing relatively inelastic properties for the expandable body, while not always required, is nevertheless preferred when maintaining a desired shape and size within the bone is important, for example, in bone graft placement or in a vertebral body, where the spinal cord is nearby. Using relatively inelastic bodies, the shape and size can be better predefined, taking into account the normal dimensions of the outside edge of the cancellous bone. Use of relatively inelastic materials also more readily permits the application of pressures equally in all directions to compress cancellous bone. Still, substantially equivalent results can usually be achieved by the use of multiple expandable bodies having highly elastic properties, if expansion is controlled by either internal or external restraints, as previously disclosed.
• IV. Confinement of Filling Material
• A. Dual Stage Filling
• FIGS. 39A to 39D show a multiple stage process for introducing filling material into a cavity formed by an expandable body in cancellous bone. The process is shown in association with treating a vertebral body. This is for the purpose of illustration. It should be appreciated that the process can be used in the treatment of all bone types.
• Use of the multi-stage process is indicated when pre-examination of the targeted bone reveals that a portion of thecortical wall28 has fractured or failed (asFIG. 39A shows at the anterior region of the vertebral body26). The failedcortical wall28 creates gaps and cracks (designated G inFIG. 39A). Typically,remnant chips500 of the failedcortical bone28 may lay in thecancellous bone32 in the region where cortical wall failure has occurred. Filling material can flow or seep through these gaps or cracks C outside of the interior volume of the bone.
• The process begins at the point where theouter guide sheath72 has been positioned and the guide pin removed in the manner previously described. The physician introduces a firstexpandable body502 into thecancellous bone32 near the failed cortical bone region, asFIG. 39A shows. The firstexpandable body502 is sized, when substantially expanded, to occupy a relatively small volume (i.e., less than about 20%) of the volume ofcancellous bone32 ininterior volume30.
• The physician expands the firstexpandable body502, compacting a relatively small region of cancellous bone. Upon collapse and removal of thefirst body502, asmall cavity504, caused by the compaction, remains (asFIG. 39B shows).
• The physician introduces theinjector tip90 and injects an aliquot of filling material96(1) (for example, about 1 cc to about 9 cc) into the formed small cavity504 (asFIG. 39B shows).
• In a short time interval (before the filling material96(1) is allowed to substantially set and harden), the physician withdraws theinjector tip90 and introduces a secondexpandable body506 into the cancellous bone32 (seeFIG. 39C). The secondexpandable body506 is larger than thefirst body502. Thesecond body506 is sized to create the desired geometry for the therapeuticmain cavity508 incancellous bone32.
• AsFIG. 39C shows, expansion of thesecond body506 displaces the earlier injected aliquot of filling material96(1) in thecavity504 toward the failed cortical wall region. The aliquot of filling material96(1) will envelopremnant chips500 of cortical bone lying in its path. The material96(1) and envelopedchips500 are pressed against the failed cortical bone region as expansion of thesecond body506 progresses. The first aliquot of filling material96(1) will begin to set and harden as the maintherapeutic cavity508 is being formed by the expansion of thesecond body506. Thesecond body506 is collapsed and removed, leaving themain cavity508.
• AsFIG. 39D shows, the first aliquot of filling material96(1) provides a viscous or (in time) hardened boarder region along the anterior edge of thecavity508. As subsequent injection of additional filling material96(2) into themain cavity508 proceeds, asFIG. 39D shows, the viscous or hardened boarder region96(1) impedes passage of the additional filling material96(2) as it fills themain cavity508. The viscous or hardened boarder region96(1) serves as a dam, keeping the additional filling material96(2) entering themain cavity508 from seeping from thevertebral body26.
• B. Interior Mesh
• FIGS. 40 and 41 show the use of aninterior mesh510 in association with the introduction of filling material into a cavity formed by an expandable body in cancellous bone. Themesh510 is shown in association with treating a vertebral body, but it should be appreciated that the process can be used in the treatment of all bone types.
• Use of themesh510 is indicated when pre-examination of the targeted bone reveals a failed cortical bone region (asFIG. 41 shows at the anterior region of the vertebral body26), coupled with the lack of enough bone matter, due to advanced disease or a complex fracture, to adequately fill the failed cortical bone region by compacting using an expandable body. Flowable cement material can flow or seep through the unfilled gaps or cracks (designated G inFIG. 41) present in the failed cortical bone region.
• Themesh510 comprises a woven structure made from biocompatible material like Goretex™ material, Nitinol™ material, or Dacron™ material. The mesh presents a surface area, which is about ⅓rd to ½ of the interior area of the maintherapeutic cavity84 formed by the selected expandable body.
• Before deploying theinjector tip90 into the formed cavity84 (which is deployed inFIG. 41 by posterolateral access), the physician drapes themesh510 over thetip90, asFIG. 40 shows. AsFIG. 41 shows, the viscous flow of fillingmaterial96 injected from thetip90 carries themesh510 into thecavity84 in advance of the fillingmaterial96. Themesh510 is urged by the fillingmaterial96 into contact with the anterior region of the bone, including the failed cortical bone region. Themesh510, permeated withviscous material96 and resting over the failed cortical bone region, impedes passage of filling material, until hardening occurs.
• V. Delivery of Therapeutic Materials
• A cavity created in cancellous bone by any of the expandable bodies described above can be filled with a medically-appropriate formulation of a drug or a growth factor.
• An expandable body can compact infected cancellous bone to create a space which can be filled with the antibiotic gel in an open or minimally invasive procedure. The cavity places and holds the required amount of drug right at the site needing treatment, and protects the drug from being washed away by blood or other fluids.
• Not only can the dose be optimized, but additional doses can be applied at later times without open surgery, enhancing the therapeutic outcome. If the required cavity for the optimal drug dose weakens the bone, the bone can be protected from future fracture with a cast or with current internal or external metal or plastic fixation devices.
• The therapeutic substance put into bone may act outside the bone as well. A formulation containing chemotherapeutic agent could be used to treat local solid tumors, localized multiple myeloma or even a nearby osteosarcoma or other tumor near that bone.
• The cavity formed by an expandable body can be filled with an appropriate supporting material, like acrylic bone cement or biocompatible bone substitute, which carries a therapeutic substance. Alternatively, the therapeutic substance can be separately delivered before injection of the filling material. Thus, using an expandable body, the physician is able to treat a fracture while also delivering a desired therapeutic substance (like an antibiotic, bone growth facer or osteoporosis drug) to the site.
• As an alternative, to deliver therapeutic substances, bodies can be dipped in a medical formulation (often a dry powder, liquid or gel) containing a medically-effective amount of any desired antibiotic, bone growth factor or other therapeutic agent to coat the body with the above-mentioned substance before it is inserted into a bone being treated. Optionally, the body can be wholly or partially expanded before the coating is performed. Optionally, the coated body can be dried with air or by other means when the applied formulation is wet, such as a liquid or a gel. The body is refolded as required and either used immediately or stored, if appropriate and desired. Coated on the body, therapeutic substances can be delivered while cancellous bone is being compressed, or with an additional body once the cavity is made.
• The methods described above can also be used to coat Gelfoam or other agents onto the body before use. Inflating the Gelfoam-coated body inside bone will further fill any cracks in fractured bone not already filled by the compressed cancellous bone.
• FIGS. 42A to 42C schematically illustrate one system and method for delivering a therapeutic substance to the bone using anexpandable body529. Thebody529 is carried at the end of thecatheter tube530, which conveys liquid to expand thebody529, as previously described.
• As shown inFIG. 42A, theexpandable body529, in a substantially expanded condition, is stabilized with aclip531 that couples thecatheter tube530 to awire532. As shown inFIG. 42B, a measured amount of gel formulation containing the desired amount ofsubstance533 is uniformly dispensed from a container534, preferably inthin lines535, onto the outer surface of thebody536. The coating substance can be the desired compound alone in its natural state (solid, liquid or gas) or in an appropriate formulation, including a dry powder, an aerosol or a solution. As shown inFIG. 42C, thecoated body537 is collapsed and allowed to dry until the gel sets. Alternatively, thebody536 can also be coated without prior expansion. The optional drying time will, of course, depend on the nature of the compound and its formulation. The coated body237 is suitable for packaging for use by a surgeon.
• Delivering a therapeutic substance on the outside of expandable body used to compact the bone, or with an expandable body introduced after the bone is compacted, is qualitatively different than putting formulated drug into the cavity. When delivered while the bone is compressed, the therapeutic substance becomes incorporated into the compacted bone. This can serve as a way to instantly formulate a slow release version of the substance. The cavity formed by the expandable body can be filled with an appropriate supporting material, like acrylic bone cement or biocompatible bone substitute, as before described.
• Medically-effective amounts of therapeutic substances are defined by their manufacturers or sponsors and are generally in the range of 10 nanograms to 50 milligrams per site, although more or less may be required in a specific case.
• For example, the cavity can accommodate a typical dose of the antibiotic, gentamicin, to treat a local osteomyelitis (bone infection). A typical dose is about 0.1 gram, although the therapeutic range for gentamicin is far greater, from 1 nanogram to 100 grams, depending on the condition being treated and the size of the area to be covered. A medically-suitable gel formulated with appropriate gel materials, such as Polyethylene glycol, can contain 1 gram of gentamicin in a set volume of gel, such as 10 cc.
• Other antibiotics that can be used to treat bone infection include, for example, ancef, nafcillin, erythromycin, tobramycin, and gentamicin. Typical bone growth factors are members of the Bone Morphogenetic Factor, Osteogenic Protein, Fibroblast Growth Factor, Insulin-Like Growth Factor and Transforming Growth Factor alpha and beta families. Chemotherapeutic and related agents include compounds such as cisolatin, doxcrubicin, daunorubicin, methotrexate, taxol and tamoxifen. Osteoporosis drugs include estrogen, calcitonin, diphosphonates, and parathyroid hormone antagonists.
• VI. Delivery of Biomaterials
• A cavity created in cancellous bone by any of the expandable bodies described above can also be filled with biomaterials.
• Biomaterials which do not flow into the formed cavity, like hydroxyapatite granules or bone mineral matrix, can be pushed down a tube with a long pin whose diameter is slightly more narrow than the inner-diameter of the outer guide sheath, using the minimally-invasive procedure. During open surgery, the physician can approach the bone in the same way.
• If the biomaterial to be inserted does not flow and should not be pushed into the cavity through the guide sheath (as in the case of the hydroxyapatite block, because that can cause damage), the physician can form the cavity using a minimally invasive approach, then punch a hole using standard tools (such as a punch, gouge or rasp) into one side of the cortical bone to allow insertion of the block.
• VII. Bone Marrow Harvesting
• Any of the expandable bodies described above can also be used in the harvesting of bone marrow for diagnostic or therapeutic purposes, for example, in the diagnosis of multiple myeloma or in the treatment of advanced cancers with bone marrow transplants.
• FIG. 47 shows asystem700 for harvesting bone marrow in a bone-marrow producing bone702. Thebone702, which is shown diagrammatically inFIG. 47, can comprise, for example, the pelvis, or a vertebral body, or a distal radius.
• Thesystem700 employs a bonemarrow harvesting tool704. Thetool704 includes acatheter tube706, which carries anexpandable body708 at its distal end. Thetool704 can be deployed into thebone702 using a minimally invasive approach, as previously described.
• Thecatheter tube706 has three concentric andindependent lumens710,712, and714 (seeFIG. 48). Theouter lumen710 communicates with the interior of thebody78 and is coupled to asource718 of an inflation liquid. Themiddle lumen712 communicates with asource720 of rinse liquid and adistal opening716 on thecatheter tube706. The center lumen714 communicates with acollection container722 and a seconddistal opening724 on thecatheter tube706.
• Thebody708 is deployed in a substantially collapsed condition, as already described. Inflation liquid, which is preferably radiopaque, is convey from thesource718 into thebody708 to expand it. AsFIG. 48 shows, thebody708 is constrained by selection of relatively inelastic materials or by exterior restraints (as previously described) to assume an elongated shape. Expansion of thebody708 creates a relatively shallow area ofcompaction726 incancellous bone728 along a relatively long length. The size and shape of thebody708 will depend upon the geometry of the harvest site and the amount of bone marrow required. In long bones, like the distal radius, and in bones with narrow width but large area, such as the ribs or pelvis, thebody728 is shaped to compress a large area but not a great depth ofcancellous bone728.
• AsFIG. 48 also shows, as thebody708 expands, rinse liquid, which can be saline or another suitable biocompatible liquid, is conveyed from thesource720 into the area726 (shown byarrows730 inFIG. 48). The rinse liquid loosens up biological components (such as red blood cells, bone cells, and immune-β cells) within the definedarea726, forming component-rich suspension732.
• Thebody708 is collapsed, and suction is applied through the lumen714. The suction draws the component-rich suspension732 from thearea726 into thecollection container722.
• The above sequence of expansion, rinsing, collapse, and aspiration can be repeated to collect additional component-rich suspension732 in thecontainer722. The position of theexpandable body708 in thebone702 can be changed, if desired, to maintain a component-rich suspension732 for harvesting.
• Use of theexpandable body708 to form the long butshallow compaction area726 permits the harvest of a significant concentration of therapeutic biological components with less damage to bone that conventional harvesting methods. If desired, standard casts or other fixation devices can be applied to thebone702 after bone marrow harvesting until thebone702 heals.
• The features of the invention are set forth in the following claims.

Claims (25)

1. A method comprising:

selecting a vertebral body for treatment, the vertebral body having a cortical wall enclosing a cancellous bone volume, the vertebral body having at least one cortical plate that is depressed due to fracture,

providing an expandable device including an expanded configuration and an unexpanded configuration,

introducing the expandable device into the vertebral body through a percutaneous access path while in the unexpanded condition,

expanding the expandable device while disposed within the cancellous bone volume from the unexpanded configuration toward the expanded configuration, and

providing an expansion barrier in association with the expandable device that directs expansion of the expandable device in a desired direction to move the fractured cortical plate toward a desired anatomic position.

2. A method according toclaim 1

further including placing a volume of filling material within the cancellous bone volume.

3. A method according toclaim 2

wherein the filling material hardens within the vertebral body.

4. A method according toclaim 2

wherein the filling material comprises bone cement.

5. A method according toclaim 1

wherein the expandable device expands by inflation.

6. A method according toclaim 1

wherein the expandable device comprises a balloon.

7. A method according toclaim 1

further including removing the expandable device from the vertebral body.

8. A method according toclaim 1

wherein the expansion barrier comprises a device sized and configured to be introduced into the vertebral body through a percutaneous access path and including a platform region sized and configured to be disposed relative to the expandable region of the first tool to define the expansion barrier.

9. A method according toclaim 8

wherein the platform region comprises an expandable body.

10. A method according toclaim 9

wherein the expandable body is inflatable.

11. A method according toclaim 1

wherein the expandable device and the expansion barrier comprise parts of a single device.

12. A method according toclaim 1

wherein the expandable device and the expansion barrier comprise separate structures.

13. A system comprising

a tool defining a percutaneous access path into a vertebral body having a cortical wall enclosing a cancellous bone volume, the vertebral body having at least one cortical plate that is depressed due to fracture,

an expandable device including an expanded configuration and an unexpanded configuration, the expandable device being sized and configured for introducing into the vertebral body through the percutaneous access path while in the unexpanded condition, the expandable body also being sized and configured to expand while disposed within the cancellous bone volume from the unexpanded configuration toward the expanded configuration,

an expansion barrier sized and configured to be placed into association with the expandable device to directs expansion of the expandable device in a desired direction to move the fractured cortical plate toward a desired anatomic position, and

a tool for placing a volume of filling material within the cancellous bone volume.

14. A system according toclaim 13

wherein the filling material comprises bone cement.

15. A system according toclaim 13

wherein the expandable device expands by inflation.

16. A system according toclaim 13

wherein the expandable device comprises a balloon.

17. A system according toclaim 13

wherein the expansion barrier comprises a device sized and configured to be introduced into the vertebral body through the percutaneous access path and including a platform region sized and configured to be disposed relative to the expandable device to define the expansion barrier.

18. A system according toclaim 17

wherein the platform region comprises an expandable body.

19. A system according toclaim 18

wherein the platform region is inflatable.

20. A system according toclaim 13

wherein the expandable device and the expansion barrier comprise parts of a single device.

21. A system according toclaim 13

wherein the expandable device and the expansion barrier comprise separate structures.

22. A method comprising:

selecting a vertebral body for treatment, the vertebral body having a cortical wall enclosing a cancellous bone volume, the vertebral body having at least one cortical plate that is depressed due to fracture,

providing a first tool comprising an expandable device including an expanded configuration and an unexpanded configuration to move the fractured cortical plate toward a desired anatomic position,

providing a second tool comprising an expansion barrier that directs expansion of the expandable device in a desired direction,

introducing the first tool and second tool into the vertebral body through a percutaneous access path,

placing the expansion barrier into association with the expandable device within the cancellous bone volume,

expanding the expandable device from the unexpanded configuration toward the expanded configuration while the expansion barrier directs expansion of the expandable device in a desired direction to move the fractured cortical plate toward a desired anatomic position, and

placing a volume of filling material within the cancellous bone volume.

23. A method according toclaim 22

wherein the filling material comprises bone cement.

24. A method according toclaim 22

wherein the expandable device expands by inflation.

25. A method according toclaim 22

wherein the expandable device comprises a balloon.

Images