Patent Publication Number: US-8540123-B2

Title: Apparatus and method for mixing and dispensing a bone cement mixture

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 12/343,964, filed on Dec. 24, 2008, now U.S. Pat. No. 8,256,949 (issued on Sep. 4, 2012), which claimed the benefit of U.S. Provisional Application Ser. No. 61/017,065, filed on Dec. 27, 2007, each of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to an apparatus, a kit and a method for mixing and dispensing a bone cement mixture. There is a clinical need to fill and stabilize damaged bones of patients, such as for example, filling defects in collapsed vertebra of patients suffering from severe back pain caused by osteoporosis, metastatic tumors or back injuries. Currently, these defects are repaired using multi-component bone cements that are mixed in open containers, transferred to a device and injected into the damaged bone where the mixture chemically reacts or cures to form a solid support structure. 
     Most widely used bone cements are based on polymethylmethacrylate (PMMA) and hydroxylapatite. These materials have relatively good strength characteristics, but have a number of drawbacks. These cements are a two-part chemically reactive system and have approximately five to ten minutes of working time once the components are mixed. As for example with the PMMA based system, one of the components is a liquid monomer methylmethacrylate (MMA), which is noxious and toxic to handle. The other component, the polymer component (PMMA), is a powder that can be difficult to mix thoroughly. Moreover, current methods of mixing these two components together are typically done by hand in an open container or dish. This procedure permits significant vaporization of the noxious liquid monomer MMA. Also, the working time increases between mixing and dispensing because once the mixture is mixed it then needs to be transferred to a syringe for injection into the damaged bone. Moreover, the working time is limited because the viscosity of the cement constantly increases during mixing, thus making transferring of the mixture to the syringe and injection of the mixture into the damaged bone more difficult. Often, a very high injection pressure and/or large bore needles may be necessary to inject the mixture, especially if it&#39;s near the end of the cement&#39;s working life. 
     SUMMARY 
     Embodiments of the present disclosure provide an apparatus, a kit and a method that facilitates mixing and dispensing the bone cement mixture such that the interventionalist and the patient have minimal exposure to the noxious vapors of the monomer, as well as providing more flexible working time for suitable injectionability of the mixture into the damaged bone. In at least some examples of the present disclosure, the bone cement components are pre-measured and contained within the apparatus, which may eliminate the possibility of spilling the bone cement components and minimize handling during preparation of the bone cement mixture. 
     In at least one embodiment of the present disclosure, an apparatus for mixing and dispensing a bone cement mixture is provided. The apparatus comprises a housing having a longitudinal axis. The housing has a first chamber formed therein that is for containing an ampoule having a first bone cement component. The housing has a second chamber formed therein for containing a second bone cement component and the first and second chambers are in fluid communication. The housing includes an outlet in fluid communication with the second chamber. Through the outlet, the bone cement mixture is dispensed from the apparatus. An ampoule breaking device is disposed within the first chamber and is configured to engage the ampoule to break the ampoule for release of the first bone cement component into the first chamber. Disposed within the second chamber is an impeller that is configured to rotate about the longitudinal axis such that the impeller mixes the first and second bone cement components together to form the bone cement mixture. Adjacent the impeller is a displacer that is configured to advance through the second chamber, receiving the impeller and advancing the bone cement mixture from the second chamber through the outlet. 
     In at least one other embodiment of the present disclosure, a bone cement substitute kit for mixing a bone cement mixture and dispensing the bone cement mixture into a damaged bone of a patient is provided. The kit comprises an ampoule having a first bone cement component disposed therein and a second bone cement component. An apparatus including a housing having a longitudinal axis. The housing has a first chamber formed therein that is for containing the ampoule. The housing has a second chamber formed therein for containing the second bone cement component and the first and second chambers are in fluid communication. The housing includes an outlet in fluid communication with the second chamber. Through the outlet, the bone cement mixture is dispensed from the apparatus. An ampoule breaking device is disposed within the first chamber and is configured to engage the ampoule to break the ampoule for release of the first bone cement component into the first chamber. Disposed within the second chamber is an impeller that is configured to rotate about the longitudinal axis such that the impeller mixes the first and second bone cement components together to form the bone cement mixture. Adjacent the impeller is a displacer that is configured to advance through the second chamber, receiving the impeller and advancing the bone cement mixture from the second chamber through the outlet. The kit further comprises a needle in fluid communication with the outlet that is configured for receiving the bone cement mixture from the apparatus and for advancing the bone cement mixture into the damaged bone of the patient. 
     In at least another embodiment of the present disclosure, a method for mixing a bone cement mixture and for dispensing the bone cement mixture into the damaged bone of a patient is provided. The method comprises providing an apparatus having a longitudinal axis, a first chamber and a second chamber in fluid communication with the first chamber. In fluid communication with the second chamber is an outlet. Disposed within the first chamber is an ampoule breaking device. An impeller is disposed within the second chamber and a displacer is disposed adjacent to the impeller. A first bone cement component is released into the first chamber by breaking the ampoule within the first chamber with the ampoule breaking device. The first bone cement component is advanced from the first chamber to the second chamber which contains a second bone cement component. By rotating the impeller about the longitudinal axis, the first and second bone cement components are mixed to form the bone cement mixture. Into the damaged bone of a patient, a needle in fluid communication with the outlet is inserted. The bone cement mixture is dispensed from the apparatus into the damaged bone of the patient via the needle by advancing the displacer through the second chamber. The displacer receives the impeller and advances the bone cement mixture from the second chamber through the outlet. The bone cement mixture is cured, which sets and hardens the bone cement mixture to stabilize the damage bone of the patient. 
     Further objects, features and advantages of the disclosure will become apparent from consideration of the following description and the appended claims when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a collapsed vertebra, 
         FIG. 2  is a partial side view of a device for stabilizing a collapsed vertebra in accordance with one embodiment of the present disclosure; 
         FIG. 3  is an enlarged view of  FIG. 2 ; 
         FIG. 4  is a partial side view of a device for stabilizing a collapsed vertebra in accordance with yet another embodiment of the present disclosure; 
         FIG. 5  is a partial side view of a stabilized collapsed vertebra in accordance with one example of the present disclosure; 
         FIG. 6  is a cross sectional side view of an apparatus for stabilizing a collapsed vertebra in accordance with yet another embodiment of the present disclosure; 
         FIG. 7  is a sectional view  7 - 7  of the apparatus depicted in  FIG. 6 ; 
         FIG. 8  is an exploded view of the apparatus depicted in  FIG. 6 ; 
         FIG. 9   a  is a perspective view of the displacer and impeller in a mixing configuration of the apparatus depicted in  FIG. 6 ; 
         FIG. 9   b  is a displacer and an impeller in an advancing configuration of the apparatus depicted in  FIG. 6 ; 
         FIG. 9   c  is a displacer and an impeller in a mixing configuration of the apparatus depicted in  FIG. 6 ; 
         FIG. 10   a  is a side sectional view of an ampoule breaking device in accordance with at least one embodiment of the present disclosure; 
         FIG. 10   b  is a side sectional view of an ampoule breaking device in accordance with at least one embodiment of the present disclosure; 
         FIG. 10   c  is a side sectional view of an ampoule breaking device in accordance with at least one embodiment of the present disclosure; 
         FIG. 11  is a partial side view of a device for stabilizing a collapsed vertebra in accordance with another embodiment of the present disclosure; 
         FIG. 12  is a side view of a bone cement substitute kit in accordance with one embodiment of the present disclosure; and 
         FIG. 13  is a flow chart for a method for stabilizing a damaged bone of a patient in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Detailed embodiments of the present disclosure are disclosed herein. It is understood however, that the disclosed embodiments are merely exemplary of the disclosure and may be embodied in various and alternative forms. The figures are not necessarily to scale; some figures may be configured to show the details of a particular component. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a representative basis with the claims and for teaching one skilled in the art to practice the present disclosure. 
     Examples of the present disclosure seek to overcome some of the concerns associated with stabilizing and/or repairing the damaged bone of a patient with bone cement while minimizing toxic effects to both the patient and the interventionalist, as well as enhancing the ease of handling for both mixing and introducing the bone cement into the damaged bone. 
     Employing the principles of the present disclosure is, for example, an apparatus, a kit and a method for stabilizing and/or repairing a damaged bone of a patient. The apparatus, which is utilized in both the kit and the method, is a closed mixing and dispensing system having two chambers that are in fluid communication with one another. Each chamber is initially for containing one of the components of a two component bone cement system. For example, an ampoule containing the first bone cement component may be contained in the first chamber. The apparatus is configured such that the first bone cement component can be released from the ampoule into the first chamber where it may be further advanced into the second chamber, which contains the second bone cement component. In one aspect, a valve may be actuated to selectively open and close fluid communication between the first and second chambers where in the open position, the first bone cement mixture may be advanced into the second chamber. Within the second chamber, an impeller mixes the first bone cement component with the second bone cement component to form a bone cement mixture. A displacer advances through the second chamber, receiving the impeller and advancing the bone cement mixture from the second chamber through an outlet and into a damaged bone of a patient via a needle in fluid communication with the outlet. The apparatus preferably mixes the bone cement components together without releasing noxious monomer fumes (i.e. in a closed or substantially closed system) contained in at least one of the bone cement components. Moreover, since the apparatus is configured to dispense the bone cement mixture, there is no need for transferring the mixture from another source into the apparatus, or from the apparatus to another dispenser. Furthermore, in at least one example, the bone cement components are pre-measured and sealably packaged within the apparatus, which preferably eliminates measuring errors and spilling of the contents during handling. Accordingly, the apparatus minimizes the mixing and dispensing time of the bone cement and thus, enhances the remaining working time for introducing the mixture into the damaged bone. Once the bone cement mixture is introduced into the damaged bone of the patient it cures to form a solid structure which stabilizes the bone. 
     Referring now to the drawings,  FIG. 1  illustrates a vertebra  10  which includes a collapsed vertebra  12  with a compression fracture  13 . The vertebra  10  may be for example in the thoracic or lower spine of the patient. In the compression fracture  13  of the vertebra  12 , the bone tissue of the vertebral body collapses. This condition is commonly caused by osteoporosis and less often by a tumor, or trauma to the back. 
     Referring now to  FIGS. 2 and 3 , at least one embodiment of the present disclosure is provided. The collapsed vertebra  12  may be stabilized by either vertebroplasty or kyphoplasty, both of which are medical procedures for restoring the structural integrity of the collapsed vertebra  12 . These procedures stabilize the collapsed vertebra  12  by filling in open spaces  15  within the vertebra  12  to provide a more continuous and solid form. Kyphoplasty may further stabilize the vertebra  12  by restoring vertebral spacing which alleviates nerve pinching from the vertebra  12 . It should be noted that the present disclosure applies to both of these medical procedures and other procedures for stabilizing and/or repairing the damaged bone of patients despite many of the various embodiments discussed herein as describing using vertebroplasty. 
     Vertebroplasty involves that the patient remain laying throughout the entire procedure. It is performed under local anesthesia and/or a light sedative. A small nick is then made in the skin near the spine and a needle  14  is inserted percutaneously. As illustrated in  FIG. 3 , the needle  14  may be inserted into the interior open spaces  15  of the vertebra  12 , for example via or through the left or right pedicle  17  of the vertebra  12 . 
     Referring to  FIGS. 4 and 5 , the bone cement mixture  18  may be dispensed from an apparatus (not shown) through the needle  14  and into the vertebra  12  to form a solid structure  64  that supports the collapsed vertebra  12 . The bone cement mixture  18  forms a solid structure  64  by chemically reacting or curing to become a solid. The stabilizing structure  64  may be formed within the collapsed vertebra  12  and may help restore vertebral spacing and alleviate nerve pinching by supporting the collapsed vertebra  12  generally in at least a compressive mode. Preferably, the structure  64  substantially fills in the open space  15  of the collapsed vertebra  12  providing a more dense and continuous vertebra  12  which enhances the mobility and relieves the pain of the patient. 
     Referring to  FIG. 11 , at least one other embodiment for stabilizing a collapsed vertebra  12  of a patient is provided. The procedure includes placing a balloon  100  into the collapsed vertebra  12 . The balloon  100  may be positioned in the vertebra  12  for example via the needle  14 , a catheter or mandrel. The balloon  100  is then filled with the bone cement mixture  18  and sealed. The balloon  100  may be sealed for example by twisting the needle  14  and shearing the corresponding end portion of the balloon  100  or alternatively by applying any suitable adhesive, such as a cyanoacrylate, to the end portion. The bone cement mixture  18  within the sealed balloon  100  cures to form the solid support structure  64  within the collapsed vertebra  12 . 
     The balloon  100  may be made of any suitable material used for medical intracorporeal balloon devices. However, a polymer impermeable to body fluids and PMMA may be preferred. An example of such material is polyethylene terephthalate (PET) or polybutylene terephthalate (PBT). 
     Referring to  FIGS. 6-9   b , at least one embodiment of an apparatus for mixing a bone cement mixture and for dispensing the bone cement mixture is provided. The apparatus  20  comprises a housing  22  having a longitudinal axis  24 . In one example, the housing  22  has a substantially cylindrical shape disposed along the longitudinal axis. 
     The housing  22  has a first chamber  26  that is formed therein. The first chamber  26  is for containing an ampoule  28  having a first bone cement component  30  (shown in  FIG. 12 ) disposed therein. In at least one example, the ampoule  28  is made of glass which is sealed (e.g. single-piece or multiple pieces without openings) and contains a liquid monomer bone cement component  30  such as MMA. The ampoule  28  may be made of other suitable materials which are chemically compatible with bone cement components and which may also be broken when a force is applied to the ampoule  28  to release the first bone cement component  30  from the ampoule  28  and into the first chamber  26 . As seen in the example of  FIG. 6 , a cap  31  is connected to housing  22  to enclose and seal chamber  26 , to prevent or limit escape of cement component  30  or fumes from it. 
     A second chamber  32  is formed within the housing  22 . The second chamber  32  is for containing a second bone cement component  34  (shown in  FIG. 12 ). The second chamber  32  is in fluid communication with the first chamber  26 . In at least one example, the first chamber is positioned above the second chamber and a port  36  provides fluid communication between the first and second chambers  26  and  32 . Cement component  34  may be pre-loaded into chamber  32  (e.g. prior to inserting ampoule  28  into chamber  26 ). For example, component  34  can be placed in chamber  26  to move through port  36  and into chamber  32 . As another example, component  34  may be placed in chamber  32  as device  20  is assembled, prior to inserting portion  23  of housing  22  into portion  25 . 
     As seen in the example of  FIG. 6 , an ampoule breaking device  40  is disposed within or beneath the first chamber  26 . The ampoule breaking device  40  is configured to engage the ampoule  28  and to break the ampoule  28 . When the ampoule  28  is broken, the first bone cement component  30  is released into the first chamber  26  and may drain, for example by force of gravity, through the port  36  and into the second chamber  32 . 
     In one example, the ampoule breaking device  40  includes a rotating member  42  disposed within the first chamber  26 . As illustrated in  FIG. 12 , the rotating member  42  engages the ampoule  28 , for example, about the head  43  of the ampoule  28 . In the illustrated embodiment, member  42  has a central lumen in which head  43  or other part of ampoule  28  can fit while the remainder of ampoule  28  is in chamber  26 . The rotating member  42  rotates about a transverse axis  48  (illustrated to the side in  FIG. 6 ), which is preferably perpendicular to the longitudinal axis  24 . It will therefore be seen that this example of member  42  is cylindrical or spherical, to permit easy rotation about axis  48 . When the rotating member  42  rotates, it breaks the ampoule  28  into pieces by applying a rotational force about the engaged head  43 , while the rest of ampoule  28  is braced against a wall of chamber  26 . 
     The ampoule breaking device  40  may further include a cord member  44  having a first end  45  for actuation by an interventionalist and a second end  47  operably connected to the rotating member  42  to rotate the rotating member  42  during actuation of the first end  45 . Cord member  44  extends through a small hole in cap  31 , as seen in one example in  FIG. 6 . The second end  47  of the cord member  44  may be wrapped about the rotating member  42  to enable rotation of the rotating member  42  from between about 0 to 180 degrees. For example, cord member  44  may extend 180 degrees, 270 degrees or more around rotating member  42 , with cord member  44  attached to the side of the lumen through rotating member  42 , or being split and attached around both sides of the lumen through rotating member  42 , in some embodiments. Preferably, a 180 degree rotation of the rotating member  42  spills out any remaining first bone cement component  30  that might be contained within the broken head  43  of the ampoule  28 . The rotating member  42 , acting as a valve, may then be turned an additional 90 degrees to a closed position (e.g. with the lumen of member  42  substantially perpendicular to axis  24  or at least with its upper opening (as seen in  FIG. 6 ) covered, as by a portion of upper portion  23  of housing  22 ) to “close-off” fluid communication between the first and second chambers  26  and  32 . 
     Referring to  FIGS. 10   a - 10   c , an alternative embodiment for the ampoule breaking device  40 ′ is provided. The ampoule breaking device  40 ′ may have a surface  52  formed at an incline to the longitudinal axis  24 . The ampoule breaking device  40 ′ may include a wedge member  54  disposed within the first chamber  26  and a manually-activated control element  56  communicating with the wedge member  54  so as to move the wedge member  54  which is engaged with the ampoule  28 . Control element  56  extends through a hole in a cap  31 ′ so that it is accessible while wedge member  54  is adjacent ampoule  28 . Cap  31 ′, like cap  31 , covers chamber  26  so as to prevent or limit escape of fumes from chamber  26 . The wedge member  54  moves the ampoule  28  against the inclined surface  52 , breaking the ampoule  28  into pieces  50 , when the manually-activated control element  56  is actuated. 
     The ampoule breaking device  40 ′ may further include a rotary valve portion  58 , which may be rotated by the interventionist to a closed position (shown in  FIG. 10   c ) which closes-off fluid communication between the first and second chambers  26  and  32 . However, when the valve  58  is in an open position (shown in  FIGS. 10   a - 10   b ), the first and second chambers  26  and  32  are in fluid communication with each other. In the illustrated example, valve  58  has an opening  58   a  that communicates with a port  36 ′ leading to second chamber  32  for fluid communication (as in  FIG. 10   a ), and when valve  58  is twisted so that opening  58   a  does not communicate with port  36 ′ (e.g.  FIG. 10   c ) fluid communication is shut off. 
     Referring back to  FIGS. 6-9   b , an impeller  62  is disposed within the second chamber  32 . The impeller  62  is configured to rotate about the longitudinal axis  24  such that the impeller  62  mixes the first and second bone cement components  30  and  34  together to form the bone cement mixture  18 . In one example, a vacuum tap may be provided (not shown), or the outlet  68  may be used, to de-gas the bone cement mixture  18  using the “utility” vacuum found at many healthcare facilities so as to minimize porosity and voids in the bone cement mixture  18  and to remove fumes generated by the mixture  18 . Moreover, in at least one embodiment, the valve (e.g. valve  58  or breaking device  40 ) is in a closed position during mixing of the first and second bone cement components  30  and  34  to prevent the mixture  18  from being advanced from the second chamber  32  to the first chamber  26 . 
     A displacer  66  is disposed adjacent to the impeller  62 . The displacer  66  is configured to advance through the second chamber  32 , receiving the impeller  62  and advancing the bone cement mixture  18  from the second chamber  32  through an outlet  68  which is in fluid communication with the second chamber  32 . The bone cement mixture  18  is dispensed from the apparatus  20  when it is advanced through the outlet  68  by the pushing action of displacer  66 . 
     In one example, the impeller  62  includes a plurality of blades  70 . Blades  70 , in the illustrated embodiments, curve outward from the middle of impeller  62 . Each blade has a roughly part-cylindrical concave surface on one side and a roughly part-cylindrical convex surface on the other side. The concave surface of one blade  70  curves smoothly into the convex surface of an adjacent blade  70 . Blades  70  engage the inside of housing  22  in the embodiment of  FIG. 7 , although it will be appreciated that other embodiments may have one or more blades  70  ending short of the housing  22 . The embodiment of impeller  62  shown in  FIGS. 7 and 9  has four blades  70 , in pairs that generally diametrically oppose each other. Such pairs form generally an S-shape, and the pairs are generally perpendicular to each other in that embodiment. A central opening is provided in impeller  62  to accommodate shaft  86 , as further discussed below. 
     The displacer  66  is configured to rotate about the longitudinal axis  24  and has a plurality of slots  72  formed therein which correspond with the blades  70 . Each of the blades  70  have a first portion  74  and a second portion  76  extending beyond the first portion  74 . The first portion  74  is disposed within a corresponding slot  72  to engage the impeller  62  such that the impeller and displacer rotate cooperatively about the longitudinal axis during mixing of the bone cement components  30  and  34 . In this embodiment, impeller  62  and displacer  66  are always keyed together, that is, at no time do blades  70  entirely leave a corresponding slot  72 . During dispensing of the bone cement mixture  18  from the apparatus  20 , the slots  72  receive the second portions  76  of the impeller  62  as the displacer  66  advances through the second chamber  32 . The keyed relationship between displacer  66  and impeller  62  (with one or more parts of blades  70  within slots  72 ) results in rotation of displacer  66  with impeller  62  as impeller  62  is turned, as further discussed below. It will be seen from  FIGS. 7 and 9  that in a particular embodiment slots  72  and blades  70  have a very close tolerance (e.g. little or no space between their respective side surfaces), so as to keep the mixed cement or components of it from getting between impeller  62  and displacer  66  to the extent possible, preserving as much of the cement as possible for dispensing through outlet  68 . 
       FIGS. 7 and 9  demonstrate embodiments of blades  70  which are substantially parallel to axis  24  (vertical in the context of  FIG. 6 ) from top portion  74  through portion  76  to the bottom of the blade and without holes or openings. The tips (adjacent housing  22 ) of blades  70  are not curved outward from the rest of the blade, as in a plowshare, in this embodiment. In other embodiments, such outward curves in a direction generally perpendicular or oblique to the remainder of blades  70  are in the tips (upper or lower) of one or more blades  70 , and/or one or more openings or holes can be provided in one or more blades  70 . The embodiment of  FIGS. 9   a  and  9   b  also show blades that have a substantially uniform height at all points from the middle of impeller  62  out to the tips of blades  70 . The cross-section of  FIGS. 6 and 8 , further shown in  FIG. 9   c , indicates an embodiment that has blades  70  with a maximum height at the tips, with the height decreasing to a minimum adjacent the opening for shaft  86  in impeller  62 , with the edges of one or more blades  70  describing a curve in cross-section which may have a substantially linear portion between the minimum height and the maximum height. The curve and changing height of such blades  70  provide a central space that enhances cross-communication of the cement or its components. Displacer  66  may have slots  72  of uniform height complementary to blades  70 , as seen in  FIGS. 9   a  and  9   b , or may have slots of varying height complementary to blades  70 , as seen in cross-section in  FIGS. 6 and 8 . The illustrated embodiment of device  20  shows impeller  62  and displacer  66  remaining in their keyed relationship, i.e., blades  70  cannot be removed from slots  70  in operation of device  20 . It will be appreciated that the uniform-height slots  72  of  FIGS. 9   a  and  9   b  can be used with the varying-height blades  70  of  FIG. 6 . 
     A filter  60  may be disposed on the displacer  66  having the port  36  formed therethrough to provide fluid communication between the first and second chambers  26  and  32 . When the ampoule  28  is broken, pieces  50  of the ampoule  28  may be received or blocked by the filter  60  while allowing the first bone cement component  30  to advance from the first chamber  26  into the second chamber  32  via the port  36 . Filter  60  is shown in  FIGS. 6 and 8 , and it will be seen that a filter  60  may be placed over opening  58   a  and/or port  36 ′ in  FIGS. 10   a - 10   c.    
     The apparatus  20  may further comprise a base portion  78  proximate the second chamber  32 . A plurality of crank arms  80  may extend outwardly from the base portion  78 . A shaft  82  has a first end  84  coupled to the crank arms  80 . End  84  is slidably coupled to arms  80  in one embodiment, with end  84  having a series of splines, cogs or teeth (not shown) engaging complementary structures on one or more of arms  80 . The shaft has a second end  86 , which may be coupled to the displacer  66 , or to the impeller  62 , or both, as seen in  FIG. 6 . In the illustrated embodiment, end  86  is securely coupled to displacer  66  by welding, adhesives or other methods, to receive rotational motion, while impeller  62  is not joined to shaft  82  but has a seal (not shown) between impeller  62  and shaft  82  to allow shaft  82  to move longitudinally through impeller  62  without losing a significant amount of cement through impeller  62 . In one example, the crank arms  80  and the shaft  82  rotate about the longitudinal axis  24 , when the crank arms  80  are actuated by an interventionalist. Actuation of the crank arms  80  produces a rotational driving force which is transferred by the shaft  82  to displacer  66 , if the second end  86  is coupled thereto. Alternatively, if the second end  86  is coupled to the impeller  62 , the shaft  82  will transfer the rotation driving force to the impeller  62 . The embodiments shown herein have impeller  62  and displacer  66  keyed together via the insertion of at least part of one or more blades  70  into one or more slots  72 , and in those embodiments impeller  62  and displacer  66  will rotate together regardless of which of them (or both) is coupled to shaft end  86 . 
     In one embodiment, there are at least three crank arms  80  positioned at an obtuse angle A of between 90 and 180 degrees from the longitudinal axis. The crank arms  80  are also spaced apart from each other such that the crank arms  80  form a stand to be supportable on a surface S and to position the apparatus  20  substantially upright. 
     In at least one embodiment, the housing  22  has a first portion  23  having the first chamber  26  formed therein and a second portion  25  having the second chamber  32  formed therein. The first portion  23 , acting as a slide, moves relative to the second portion  25  along the longitudinal axis  24 . The first portion  23  slidingly engages the displacer  66 . 
     The apparatus  20  may further comprise a handle  94  disposed about the first portion  23 . The handle  94  and the first portion  23  each have at least one flange  93  and  95  in the illustrated embodiment. The flanges  93  and  95  may be defined by grooves and/or threads formed respectively in the handle  94  and the first portion  23 . This embodiment of handle  94  includes a groove  96   a  that fits around a boss or flange  96   b  of housing  22 , so that handle  94  can rotate around housing  22  but not move longitudinally along housing  22 . When the handle  93  is actuated, for example by rotating it about the first portion  23 , the flange  93  of the handle  94  cooperates with the flange  95  of the first portion  23  to advance the first portion  23  towards the displacer  66  and sliding both within portion  25  of housing  22 , such that the displacer  66  is advanced in the second chamber  32 . In embodiments in which shaft  82  is securely coupled to displacer  66  and is longitudinally slidable through impeller  62 , the advancing of displacer  66  causes shaft  82  to move through impeller  62 . In a particular embodiment, the distance between a surface on which arms  80  rest and the lowermost point of end  84  of shaft  82  is at least approximately the same as the distance displacer  66  can travel with respect to impeller  62 . In that case, when displacer  66  is moved as far as it can with respect to impeller  62  and thus forces as much cement as it can out of outlet  68 , end  84  of shaft  82  will reach a surface on which arms  80  rest, providing an additional stop and support which provides an external indication of full dispensing, and can prevent significant damage to device  20  from over-tightening of handle  94 . 
     Device  20  may be provided initially complete with second cement component  34  (for example, powdered or dry PMMA) in chamber  32  and ampoule  28  (with first cement component  30 , such as liquid MMA, inside) in chamber  26 , so that no transfer of components by the interventionalist or other person into device  20  is required. In other embodiments, a measure of powdered cement component may be placed in chamber  32  by the interventionalist or other person, and then displacer  66 , housing portion  23 , handle  94  and other parts of device  20  may be assembled. Similarly, in other embodiments ampoule  28  may be provided separately from device  20 , and at the appropriate time be placed in chamber  26  and enclosed therein by cap  31 ,  31 ′. 
     Device  20  may be placed on a table or other suitable surface, supported by arms  80 . As discussed above, ampoule  28  is broken and cement component  30  exits ampoule  28  and through port  36 ,  36 ′ to chamber  32 , where it encounters cement component  34 . With the components together, housing  22  is grasped with one hand, as by picking it up, and arms  80  are turned with the other hand. As noted previously, turning arms  80  results in turning impeller  62 , by way of the couplings between shaft  82  and arms  80  and between shaft  82  and displacer  66 , and due to the keyed relationship between displacer  66  and impeller  62 . The rotation of impeller  62  mixes the cement with cross-communication of the cement and/or components among the areas bounded by blades  70 . 
     When the cement has been mixed sufficiently, device  20  can be placed again on a surface on arms  80 . Turning handle  94  with respect to housing portion  22  results in a force pushing housing portion  23  downward (toward arms  80 ), which force is transmitted to displacer  66 . Displacer  66  travels down over impeller  62 , as described above, and forces cement in chamber  32  out through outlet  68 . 
     Referring to  FIG. 12 , at least one embodiment of a bone cement substitute kit is provided. The kit  97  includes the apparatus  20  as discussed in the foregoing paragraphs as well as a needle  14 . The needle  14  is in fluid communication with the apparatus  20  and is for advancing the bone cement mixture  18  into the collapsed vertebra  12 . The needle  14  may have a beveled end  16  for easy insertion and removal from the collapsed vertebra  12 . The other end  17  of the needle may be directly coupled to the apparatus  20 , preferably with the outlet  68 , or indirectly coupled via tubing  96 . The tubing  96  provides fluid communication between the apparatus  20  and the needle  14 . Preferably, the tubing  96  may have an elbow to enable the interventionalist to operate the apparatus  20  from outside an X-ray field during injection of the bone cement mixture  18  into the damaged bone. Moreover, the tubing may be pressure sensitive, indicating when the collapsed vertebra  12  is filled with the bone cement mixture  18  by changing color caused from an increase in back-pressure from the bone cement mixture  18 . 
     The kit  97  may further comprise a first and a second bone cement component  30  and  34 . The first bone cement component  30  is preferably contained within the ampoule  28 , which is preferably contained within the first chamber  26  of the apparatus  20 . The second bone cement component  34  is preferably contained within the second chamber  32 , and may be placed there as discussed above. In one example the first bone cement component  30  is MMA and the second bone cement component  34  is PMMA. 
     The kit  97  may further include a balloon  100  and a timer  98 . The balloon  100  is for positioning within the vertebra  12 , for example, via the needle  14 , a catheter or mandrel. The balloon  100  may be filled with the bone cement mixture and sealed to stabilize the collapsed vertebra  12 . The timer may be used to time mixing and/or curing of the bone cement mixture  18 . 
     Referring to  FIG. 13 , a method for mixing a bone cement mixture and dispensing the bone cement mixture into a damaged bone of a patient is provided. The method includes providing an apparatus (block  102 ), as discussed in the foregoing paragraphs. 
     A first bone cement component is released (block  104 ) from an ampoule into a first chamber. This may include breaking the ampoule within the first chamber with an ampoule breaking device as discussed above. 
     The first bone cement component may be filtered (block  106 ) by a filter in fluid communication with the first and second chambers. Pieces from the broken ampoule are received or blocked by the filter. 
     The first bone cement component is advanced from the first chamber into to the second chamber (block  108 ). The second chamber contains a second bone cement component. In one aspect, a valve may then be closed such that fluid communication between the first and second chambers is closed-off. 
     The first and second bone cement components are mixed together (block  110 ) to form a bone cement mixture. This may include rotating an impeller about a longitudinal axis to mix the bone cement components as discussed above. 
     A needle is inserted (block  112 ) into the damaged bone of the patient. The needle is in fluid communication with the apparatus. 
     The bone cement mixture is dispensed from the apparatus into the damaged bone of the patient via the needle (block  114 ). This can include advancing a displacer through the second chamber of the apparatus, where the displacer receives the impeller and advances the bone cement mixture from the second chamber and through the needle as discussed above. The bone cement mixture is then allowed to cure (block  116 ) to stabilize the damaged bone of a patient. 
     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of the implementation of the principles of this disclosure. This description is not intended to limit the scope or application of this disclosure in that the disclosure is susceptible to modification variation and change, without departing from the spirit of this disclosure, as defined in the following claims.