Abstract:
A method mixes and transfers a bone filling material. The method makes use of a receptacle for receiving components in an unmixed condition. A mixing element can be inserted into the receptacle to mix the components. An actuator having a drive member and a driven member is removably coupled to the mixing element.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a divisional of co-pending U.S. patent application Ser. No. 09/980,648, filed Oct. 25, 2001 and entitled “Systems and Methods for Mixing and Transferring Flowable Materials,” which claims the benefit of U.S. provisional application Ser. No. 60/243,195 filed Oct. 25, 2000. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to systems and methods for mixing materials together and transferring the materials into other instruments, particularly for use in the medical field.  
       BACKGROUND OF THE INVENTION  
       [0003]     Current methods and apparatus for mixing a plurality of materials together in the medical field, e.g., poly(methyl methacrylate) bone cement comprising a powdered material with a liquid monomer to be used as a bone filling material, often yield unsatisfactory results.  
         [0004]     Typically, in a surgical setting, the instruments employed for this purpose are a small bowl for receiving the components and a stick (such as a common tongue depressor) for mixing the components in the bowl. If a powdered material is employed, it is usually poured directly from its container into the bowl. Consequently, the process is often messy due to spillage of the powdered material. Where one of the components is a liquid monomer, the process can involve the release of noxious fumes released by the liquid monomer.  
         [0005]     After the components are mixed, as in the case of a bone filling material, further problems are encountered. When the bone filling material is to be dispensed into a cavity in bone, the common practice is to first transfer the material into a syringe and then to transfer the material into the instrument for delivery to the cavity. The syringe is loaded by either vacuuming up the material by withdrawing the fully engaged plunger through the syringe body, or by removing the syringe plunger and pouring the material into the back of the syringe and reinserting the plunger. This is a difficult and messy procedure. Thus, there is a need for providing a way of mixing materials while containing the fumes and to easily and cleanly transfer or dispense the contents into other instruments.  
       SUMMARY OF THE INVENTION  
       [0006]     Although various manufacturers of medical products have attempted to develop, manufacture and supply various systems for mixing and/or dispensing poly(methyl methacrylate) bone cement (e.g., DePuy—see PCT Publication No. WO97/21485, Immedica—see PCT Publication No. WO99/37256, and Stryker—see U.S. Pat. No. 6,042,262) such systems are often expensive, too complex, require extensive and/or externally-powered accessories, or cannot mix small quantities of bone filler material. Because of these and other problems, there is a need for improved systems and methods for mixing and transferring materials, particularly in the medical field.  
         [0007]     One aspect of the invention provides hand-held systems and associated methods for using the systems, which accurately measure the components before mixing, contain the components during mixing, mechanically mix or stir the bone filling material, and conveniently and cleanly transfer or dispense the mixture into other instruments. The hand-held system provides a simple, quick and cost-effective way to mix and transfer materials.  
         [0008]     Another aspect of the invention provides hand-held systems and associated methods for using the systems which fully contain the components during mixing (desirably eliminating any spillage of noxious fumes released during mixing).  
         [0009]     One aspect of the invention provides an assembly that includes a receptacle for receiving components, e.g., of a bone filling material, in an unmixed condition. The assembly also includes a mixing element that is insertable into the receptacle to mix the components. The assembly further includes an actuator for the mixing element, including a drive member and a driven member coupled to the drive member. The actuator is removably coupled to the mixing element. After thorough mixing, the mixing element can be removed and/or a plunger is inserted into the receptacle to transfer or dispense the mixture.  
         [0010]     Another aspect of the invention provides a method for mixing and transferring a flowable material. The method provides a device for mixing and dispensing a bone filling material comprising a receptacle having a sidewall peripherally surrounding an interior for receiving components of the bone filling material in an unmixed condition. The receptacle includes a first end region and a second end region oppositely spaced from the first end region. A dispenser outlet is formed on the sidewall adjacent the second end region and communicates with the interior of the receptacle. A base on the second end region supports the first end region in an upright condition and is sized and configured to resist tipping of the receptacle during use.  
         [0011]     The method also provides a mixing element sized to be inserted into the interior of the receptacle through the first end region while the base supports the first end region in the upright condition, to mix the components of the bone filling material within the interior of the receptacle. The mixing element is also sized to be withdrawn from the interior of the receptacle through the upright first end region after mixing of the components.  
         [0012]     The method also provides a plunger sized to be inserted, after withdrawal of the mixing element, into the interior of the receptacle through the first end region for advancement through the interior toward the second end region, to dispense the mixed components of the bone filling material through the dispenser outlet while the base supports the first end region in the upright condition.  
         [0013]     The method places components of the bone filling material in an unmixed condition into the interior. While the base supports the first end region in the upright condition, the method inserts the mixing element into the interior of the receptacle through the first end region. Also while the base supports the first end region in the upright condition, the method manipulates the mixing element to mix the components of the bone filling material within the interior of the receptacle.  
         [0014]     After mixing of the components, and while the base supports the first end region in the upright condition, the method withdraws the mixing element from the interior of the receptacle through the upright first end region. The method withdraws the mixing element from the interior of the receptacle, and while the base supports the first end region in the upright condition, inserts the plunger into the interior.  
         [0015]     While the base supports the first end region in the upright condition, the method advances the plunger through the interior toward the second end region to dispense the mixed components of the bone filling material through the dispenser outlet.  
         [0016]     In one embodiment, the mixing element comprises a paddle that mixes components in response to rotation. The paddle can include a structure to promote mixing of components, such as, e.g., a plurality of apertures. In this arrangement, the actuator includes a drive member that rotates a paddle. The actuator can include a drive train, e.g., a planetary gear train, that couples a drive member to a driven member. Desirably, the drive member is operable manually, such that no external power source is required.  
         [0017]     In one embodiment, the receptacle comprises a dispensing valve. The dispensing valve is closed during the mixing step and is manually operated to open and close when performing the transferring or dispensing step. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIGS. 1A and 1B  are plane views of various embodiments of a kit that contains the component parts of systems for mixing and dispensing flowable materials that embody features of the invention;  
         [0019]      FIGS. 2A and 2B  are perspective views of various embodiments of receptacles that form a part of the system shown in  FIGS. 1A and 1B ;  
         [0020]      FIG. 3  is a perspective view of a stand that forms a part of the system shown in  FIG. 1A ;  
         [0021]      FIG. 4  is perspective side view of an actuator that can form a part of the systems shown in  FIGS. 1A and 1B ;  
         [0022]      FIGS. 4A-4F  are perspective side views of alternate embodiments of actuator handle designs;  
         [0023]      FIG. 5A  is a bottom view of the actuator shown in  FIG. 4 ;  
         [0024]      FIG. 5B  is a bottom view of an alternate embodiment of an actuator;  
         [0025]      FIG. 6A  is an exploded, perspective view of the actuator shown in  FIG. 4 ;  
         [0026]      FIG. 6B  is an exploded, perspective view of an alternate embodiment of an actuator;  
         [0027]      FIG. 7  is a perspective view of one embodiment of a mixing element that forms a part of the system shown in  FIGS. 1A and 1B ;  
         [0028]      FIG. 8  is a perspective view of another embodiment of the mixing element that forms a part of the system shown in  FIGS. 1A and 1B ;  
         [0029]      FIG. 9  is a perspective view of another embodiment of the mixing element that forms a part of the system show in  FIGS. 1A and 1B ;  
         [0030]      FIG. 10  is a perspective view of the receptacle shown in  FIG. 2  inserted into the stand shown in  FIG. 3 , and also showing a component being added to the receptacle;  
         [0031]      FIG. 11  is a perspective view of the proximal end of the mixing element shown in  FIG. 8  inserted into the exterior side of the lower half of the actuator shown in  FIG. 4 ;  
         [0032]      FIG. 12  is an exploded view of the actuator, mixing element, receptacle, and stand assembly, as also shown in assembled view in  FIG. 13 ;  
         [0033]      FIG. 13  is a perspective view of the assembly shown in  FIG. 12 , showing the actuator grasped by one hand and being manually rotated, and showing the receptacle being grasped by the other hand of the operator, the rotation of the actuator serving to mix materials in the receptacle;  
         [0034]      FIG. 14  is a perspective view showing the plunger being inserted into the receptacle after the materials have been mixed in the receptacle;  
         [0035]      FIG. 15  is a perspective view showing the stand being removed from the receptacle prior to dispensing material from the receptacle;  
         [0036]      FIG. 16  is a perspective view of the plunger inserted into the receptacle containing the material, which is now ready to be dispensed;  
         [0037]      FIG. 17  is a perspective view of the material mixed within the receptacle being dispensed from the receptacle;  
         [0038]      FIG. 18  is a bottom view of the upper half of the actuator that forms part of the system shown in  FIG. 1B ;  
         [0039]      FIG. 19  is a perspective view of the plunger assembly showing an opening for an air purge valve;  
         [0040]      FIG. 20  is a perspective view of one embodiment of a dispenser valve with an assembly for securing to the receptacle of  FIG. 2B ;  
         [0041]      FIG. 21  is a perspective view of the receptacle of  FIG. 2B  with an optional attached vacuum line; and  
         [0042]      FIG. 22  is a partially cut-away view of the receptacle of  FIG. 21 ;  
         [0043]      FIG. 23  is another partially cut-away view of the receptacle of  FIG. 21 ;  
         [0044]      FIG. 24A  is a perspective view of an embodiment of a collapsible mixing element suited for use in the receptacle of  FIG. 21 ;  
         [0045]      FIG. 24B  is a side view of the collapsible mixing element of  FIG. 24A ;  
         [0046]      FIG. 25  is a perspective view of another embodiment of a collapsible mixing element suited for use in the receptacle of  FIG. 21 ;  
         [0047]      FIG. 26  is a perspective view of another embodiment of a collapsible mixing element suited for use in the receptacle of  FIG. 21 . 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0048]     The embodiments describe systems and methods that embody features of the invention in the context of mixing a bone filling material. It should be appreciated, however, that the systems and methods so described are not limited in their application to the mixing of bone filling material. The systems and methods are applicable for use in diverse applications, both inside and outside the medical field.  
         [0049]     It should also be appreciated that the various component parts of the inventions described herein can be comprised of non-ferrous and/or non-metallic materials, which would permit the various embodiments to be utilized in a magnetic and/or whole room MRI environment.  
         [0000]     I. The Component Parts  
         [0050]      FIG. 1A  shows component parts, arranged as a kit  200 , that are usable in association with each other to form a material mixing and transferring system. The number and structure of the component parts can vary. In  FIG. 1A , the kit  200  includes a receptacle  12  for receiving materials for mixing and for, after mixing, transferring or dispensing the materials a stand  14  for receiving the receptable  12 ; a mixing element  16  that can be inserted into the receptacle  12  to mix the materials; an actuator  18  to drive the mixing element  16 ; a plunger  20  that can be inserted into the receptacle  12  to urge mixed materials from the receptacle  12 ; a dispensing element  22  to dispense the mixed materials urged from the receptacle  12 ; and a measuring device  24  to measure materials placed in the receptacle  12  for mixing.  
         [0051]     Desirably, the components  12 ,  14 ,  16 ,  18 ,  20 ,  22  and  24  comprise a substantially rigid metal, plastic or ceramic material. In one embodiment, the components  12 ,  14 ,  16 ,  20 ,  22  and  24  comprise polypropylene, and component  18  comprises Acetal homopolymer (DELRIN® material from DuPont Corporation) or a clear or colored nylon. The component materials will desirably be unaffected by contact with the bone filler material and/or sterilizable by gamma radiation. Of course, various other alternative materials can be used, including materials which are capable of withstanding contact with monomer without significant degradation for limited periods of time.  
         [0052]     A. The Receptacle  
         [0053]     As shown in  FIG. 2A , the receptacle  12  has a proximal end  30  and a distal end  32 . The receptacle  12  further has an interior bore  37  which desirably extends from the proximal end  30  to the distal end  32 . The distal end  32  carries a distal tip  34 , through which one may dispense a material such as a bone filling material.  
         [0054]     The receptacle  12  is sized to separately accommodate the mixing element  16  and the plunger  20  at different stages of use. The interior surface of the distal tip  34  is sized to support the distal tip  62  of the mixing element  16  during use, as will be described in greater detail later. The proximal end  30  carries a set of tabs  36  on an outer surface  33  of the receptacle  12 , to couple the receptacle to the actuator  18 , which, in turn, releasably couples to the proximal end  56  of the mixing element  16 . When the plunger  20  is inserted into the receptacle  12 , the tabs  36  also allow the physician to grasp and operate the receptacle  12  and plunger  20  like a syringe, for dispensing materials after mixing, as will be described later.  
         [0055]     In one embodiment, the receptacle  12  has a volume of approximately seventy cubic centimeters (70 cc). Of course, other size receptacles  12  could be used, depending upon the size of the mixing element  16  and other associated components, and the desired amount of filler material to be mixed. Other representative sizes could include five (5), ten (10) and twenty (20) cc syringes. The outer surface  33  of the receptacle  12  desirably includes a graduated scale  39  showing the volume inside the receptacle  12 . Preferably, the graduated scale  39  begins near the distal tip  34  of the receptacle  12 . The receptacle  12  is desirably made of transparent polypropylene to allow viewing of the materials to be mixed when placed in the receptacle  12 , during mixing and during transfer.  
         [0056]     In an alternate embodiment, as shown in  FIG. 2B , the receptacle  12  at the distal end  32  comprises a receptacle base  35 . The receptacle base  35  is generally hemispherical in shape and supports the interior bore  37  of the receptacle  12 . Within the interior bore  37  of the receptacle  12 , at the receptacle base  35 , is located a central neck (not shown) that is sized to accept and to securely hold the distal tip  62  of the mixing element  16 , as previously described in connection with the previous embodiment. The receptacle base  35  desirably stabilizes and elevates the interior bore  37  and allows for easier dispensing or transfer of the mixed material. The receptacle base  35  is sized to provide a solid footing to minimize tipping of the receptacle  12 . The receptacle  12  has an outlet  34 B for dispensing the mixed bone filling material.  
         [0057]     If desired, the receptacle  12  may incorporate a vacuum attachment  31  (see  FIG. 2B ) for a standard operating room suite vacuum hose, to evacuate fumes in the receptacle  12  and/or degas the material. The vacuum hose may be further secured by an indent  31 A in the receptacle base  35 . If further desired, the receptacle  12  may form a cartridge for a bone filling material delivery gun.  
         [0058]     B. The Stand  
         [0059]     In the system shown in  FIG. 1A , the stand  14  (see  FIG. 3 ) supports the receptacle  12  during mixing. The stand  14  has an upper side  40  and a lower side  42 . The upper side  40  has a central neck  44  that is sized to accept and to securely hold the distal end  32  of the receptacle  12 . Centered within the neck  44  is a small chamber  46  that is sized to accept the distal tip  34  of the receptacle  12 . The lower side  42  of the stand  14  has a flat surface which allows the stand  14  to sit evenly on a surface such as a treatment table.  
         [0060]     A separate stand  14  is not absolutely necessary for the system shown in  FIG. 1B  as the receptacle base  35  is incorporated directly into the receptacle  12 .  
         [0061]     C. The Mixing Element  
         [0062]     The mixing element  16  can be variously configured, and  FIGS. 7, 8  and  9  show different representative configurations. In use, the mixing element  16  rotates within the receptacle  12  to mix the materials contained in the receptacle.  
         [0063]     In the various described configurations, the mixing element  16  has an upper side  50  and a lower side  52 . In these embodiments, the upper and lower sides  50  and  52  can have an outwardly extending central rib  51  that acts as a stiffener to maintain integrity of the mixing element  16 . The mixing element  16  may also include one or more crosswise ribs  53 .  
         [0064]     The mixing element  16  has a proximal end  56  and a distal end  57 . The distal end  57  desirably carries a flat tip  62  that is adapted to fit into the distal tip  34  of the receptacle  12 . The distal tip  62  of the mixing element  16  desirably mixes the components located in the distal tip  34  of the receptacle  12 . The distal tip  62  also desirably acts as a bearing surface within the distal tip  34  of the receptacle  12 , to keep the mixing element  16  centered within the receptacle  12  as it rotates, as well as constraining side-to-side movement of the mixing element  16  within the receptacle  12 . The distal tip  62  also acts to maintain secure engagement of the mixing element  16  to the actuator  18   
         [0065]     If desired, the proximal end  56  can carry a solid cylindrical tip  58 , although the proximal end  56  could be various configurations suitable for attachment to the actuator  18 . The tip  58  is adapted to couple to the actuator  18 , as will be described in greater detail later. The tip  58  has a crosspiece  60  that facilitates the transmission of rotational forces from the actuator  18  to the mixing element  16  as shown in  FIGS. 7, 8  and  9 . The crosspiece  60  also acts to firmly engage the mixing element  16  with the keyway  89  of the actuator  18  by snapping in place. The tip  58  may also contain ridges  59  as shown in  FIG. 9  to impart further strength and stability.  
         [0066]     The mixing element  16  also desirably has one or more apertures  61 ,  63 ,  65 ,  67 ,  68 , and  69 , as shown in  FIGS. 7-9 . The apertures  61 ,  63 ,  65 ,  67 ,  68 , and  69  function to assist in mixing the chosen components, such as a powdered material and a liquid monomer, together. The apertures  61 ,  63 ,  65 ,  67 ,  68 , and  69  are desirably large enough to allow some of the mixture to flow through the mixing element  16 , thereby allowing the mixing element  16  to rotate within the receptacle  12  with a minimum of resistance and maximizing the mixing of the chosen mixing materials. If the sizes of the apertures  61 ,  63 ,  65 ,  67 ,  68 , and  69  are increased, less resistance to rotation is noted. However, there is a concomitant need for additional rotation of the mixing element  16  in the mixture to ensure thorough mixing. Larger apertures ease the mixing process, while smaller apertures may result in the components “riding up” the mixing element  16 . In such a case, the mixing must be stopped momentarily in order to allow the components to fall back into the mixture.  
         [0067]     Desirably, the mixing element  16  is sized to extend substantially across the interior of the receptacle  12 . Such an arrangement can facilitate mixing of the powder and liquid components, because rotation of the mixing element  16  can “scrape” the powdered and liquid components off the inner walls of the receptacle, ensuring even mixing of the components. While actual physical contact between the side walls of the receptacle  12  and the mixing element  16  are not absolutely necessary, in least one embodiment the mixing element  16  and the side walls of the receptacle  12  are in very close proximity.  
         [0068]     In the embodiment shown in  FIG. 8 , the mixing element  16  desirably has a series of small, evenly spaced apertures  65  beginning near the proximal end  56  of the mixing element  16 , followed by at least two large apertures  69  extending toward the distal end  57  of the mixing element  16 , and at least two intermediate sized apertures  67  at the distal end  57 . Such an embodiment allows for easier mixing and minimizes the previously mentioned “riding up” of the mixture; however, this embodiment typically requires additional rotations of the actuator  18 . In this embodiment approximately five to twenty rotations of the actuator  18  should be sufficient to ensure a proper mixture in the case of a bone filling material.  
         [0069]     In the embodiment shown in  FIG. 7 , the mixing element  16  has a plurality of evenly spaced apertures  61  that are positioned parallel to the rib  51 , and the mixing element  16  further has at least two apertures  63  at the distal tip  62 . This embodiment requires approximately five to ten rotations of the actuator  18  to mix a proper bone filling material. Although fewer rotations are needed with this embodiment, this embodiment typically requires more strength for the rotations on behalf of the operator than does the previously mentioned embodiment. Additionally, it is occasionally necessary to stop during the mixing process to allow the components to fall back into the mixture.  
         [0070]     In the embodiment shown in  FIG. 9 , the mixing element  16  has two larger apertures  68  beginning near the proximal end  58  of the mixing element  16 , followed by at least two large apertures  69  extending toward the distal end  57 . This embodiment requires approximately fifteen to twenty rotations of the actuator  18  to properly mix the bone filling material. The minimal surface area of the mixing element  16  as shown in  FIG. 9  allows only a small amount of bone filler material to be retained on the mixing element  16  when it is removed from the receptacle  12  after thorough mixing.  
         [0071]     In other alternative embodiments, the mixing element  16  could incorporate any number of apertures of various sizes and shapes (not shown).  
         [0072]     D. The Actuator  
         [0073]     The actuator  18  (see  FIGS. 4 and 5 A and  5 B) drives the mixing element  16 . Desirably, the actuator  18  is formed from DELRIN□ material or a clear or colored nylon. As shown in  FIG. 4 , the actuator  18  is in a palm-sized, cylindrical shape.  
         [0074]     The actuator  18  has an outer surface  70  that, if desired, may be knurled or indented to facilitate gripping by the user.  FIGS. 4A-4F  show various alternative handle designs for an actuator. The actuator  18  has an upper half  72  and a lower half  74  (see also  FIGS. 6A and 6B ) that are adapted to be connected together in various ways, including fasteners, adhesives, or a snap-fit.  
         [0075]     The upper half  72  of the actuator  18  functions as a drive member, while the lower half  74  of the actuator  18  is a driven member. The upper half  72  rotates relative to the lower half  74 .  
         [0076]     Both the upper half  72  and the lower half  74  of the actuator  18  have an interior side  76  and an exterior side  78 . As shown in  FIG. 6A , the interior side  76  of the upper half  72  contains a ring gear  73 . The interior side  76  of the lower half  74  contains a planetary gear arrangement  84  that meshes with the ring gear  73 .  
         [0077]     The planetary gear arrangement  84  includes a sun gear  86  and one or more planet gears  88 . The sun gear  86  is fixed axially to the lower half  74  of the actuator  18  by means of a screw  95 . The planet gears  88  are fixed to a retainer ring  92  by screws  94 . In one alternative embodiment, the planet gears  88  would comprise two gears, each gear positioned on opposite sides of the sun gear  86 .  
         [0078]     The teeth of the planet gears  88  mesh with the teeth of the ring gear  73 . The teeth of the planet gears  88  also mesh with the sun gear  86 . Rotation of the upper half  72  of the actuator  18  relative to the lower half  74  of the actuator  18  rotates the ring gear  73 . This, in turn, imparts rotation to the planet gears  88  within the stationary lower half  74  of the actuator  18 . Rotation of the planet gears  88 , in turn, rotates the sun gear  86  within the lower half  74  of the actuator  18 . In the embodiment where there are three planet gears  88 , a single rotation of the ring gear  73  (i.e., the upper half  72  of the actuator  18 ) equals approximately four rotations of the sun gear  86  within the lower half  74  of the actuator  18 . In the embodiment where there are two planet gears  88 , a single rotation of the ring gear  73  equals approximately three rotations of the sun gear  86 .  
         [0079]     As shown in  FIG. 5A , the exterior side  78  of the lower half  74  of the actuator  18  has a central slot  96  which receives the cylindrical tip  58  of the mixing element  16 . An axle  87  projecting from the sun gear  86  (see  FIG. 6A ) extends into the slot  96 . The crosspiece  60  on the tip  58  fits into a keyway  89  on the axle  87  (see  FIG. 5A ), which couples the mixing element  16  to the sun gear  86 . Thus, rotation of the sun gear  86  imparts rotation to the mixing element  16 .  
         [0080]     Additionally, the exterior side  78  of the lower half  74  has stabilizing structure  98  (see  FIG. 5A ). The structure  98  abuts against and/or grips the tabs  36  of the receptacle  12  to prevent the receptacle  12  from rotating while rotation is imparted by the sun gear  86  to the mixing element  16 . The stabilizing structure  98  is secured to the lower half  74  of the exterior side  78  by fasteners  99 . If desired, the actuator  18  may incorporate an attachment for a standard operating room suite vacuum hose (not shown), to evacuate fumes within the receptacle  12 .  
         [0081]     In an alternate embodiment (see  FIG. 6B ), the upper half  72  of the actuator  18  has an integral ring gear  73  adapted into the interior surface  71  (see  FIG. 18 ) of the actuator  18 . The lower half  74  of the actuator  18  has a planetary gear arrangement  84  that meshes with the ring gear  73 . The planetary gear arrangement  84  includes a sun gear  86  and a plurality of planet gears  88 . Desirably, the planetary gear arrangement  88  comprises two planet gears  88 . The sun gear  86  is fixed axially to the lower half  74  of the actuator  18  by means of an axle  87 . The axle  87  is adapted at the top to snap-fit with the upper half  72  and is adapted at the bottom to receive the tip  58  of the mixing element  16 . The middle section of the axle  87  is squared off to hold the sun gear  86  in place and to receive rotational forces imparted by the sun gear  86 .  
         [0082]     The planet gears  88  are fixed to the lower half  74  of the actuator  18  by hollow gear posts  93 . The retainer ring  92  has retention tabs  90  which fit through the central bore of the planet gears  88  and extend into the hollow gear posts  93  (see  FIG. 6B ). The retention tabs  90  have small tangs extending downward through the hollow gear posts  93  to securely engage the retainer ring  92  to the lower half  74  of the actuator  18 . The retainer ring  92  also desirably has stabilizer feet  97  extending downward to provide strength and stabilization to the planetary gear arrangement  84 .  
         [0083]     As shown in  FIG. 5B , the exterior side  78  of the lower half  74  of the actuator  18  has a stabilizing structure  98 B which is generally oblong to accommodate insertion of the receptacle  12 . The oblong shape of the stabilizing structure  98 B prevents the receptacle  12  from rotating while rotation is imparted by the sun gear  86  to the axle  87  which couples to the mixing element  16 .  
         [0084]     E. The Plunger  
         [0085]     The plunger  20  (see  FIGS. 14 and 16 ) fits into the bore  37  of the receptacle  12 . Advancement of the plunger  20  within the receptacle  12  desirably expels air from the receptacle  12 , as well as dispenses material from the receptacle  12 .  
         [0086]     As shown in  FIG. 19  the plunger  20  may also desirably contain one or more openings  103  for a valve that automatically purges the air in the receptacle  12  between the plunger  20  and mixed bone filling material. The plunger  20  can contain a seal  101  made from various materials including, but not limited to, a non-rigid material that is unaffected by contact with the mixed bone filling material. In one embodiment, the plunger  20  can contain a valve with a small ball bearing (not shown) which allows air to escape as the plunger  20  is advanced through the receptacle  12 . The ball bearing (not shown) may be made from a plastic material that is less dense than the bone filling material. As the plunger  20  contacts the viscous bone filling material, the ball bearing is forced up into a closed position. Purging the air allows for direct contact between the plunger  20  and material, which provides for improved dispensing control of the material.  
         [0087]     F. The Dispensing Element  
         [0088]     In the system shown in  FIG. 1A , the dispensing element  22  comprises a nozzle  100  that is adapted to fit on the distal tip  34  of the receptacle  12  (see  FIG. 17 ). In another embodiment, a LUER® fitting (not shown) is incorporated into the distal tip  34  of the receptacle  12 . In another embodiment, a fitting (not shown) is incorporated into the distal tip  34  of the receptacle  12 , the fitting being adapted to mate with the body of a 5 cc or 10 cc syringe. In another embodiment, tubing (not shown) is incorporated into the distal tip  34  of the receptacle  12 , the tubing being adapted to fit within a 5 cc or 10 cc syringe body.  
         [0089]     In the system shown in  FIG. 1B , the dispensing element  22  desirably snap fits onto the distal end  32  of the receptacle  12  by means of clips  121  (see  FIG. 20 ). The dispensing element  22  may also be attached to the receptacle  12  by other means, such as with adhesive, welding or by other means known in the art. The dispensing element  22  desirably mates with the outlet  34 B of the receptacle  12  (see  FIG. 2B ). A stopcock valve (not shown), or other type of suitably valve, can be located inside the valve body  125  and have a outlet  127  for the mixed material. The dispensing element  22  can have one or more dispensing handles  123  located at the end(s) of the valve body  125 . Two dispensing handles  123 , as shown in  FIG. 20 , can allow for either right- or left-handed operation of the dispensing element  22 . A LUER® fitting  129  is desirably incorporated onto the valve body  125 , to facilitate attachment of a syringe or threaded bone filling device. Of course, any number of other types of fittings or tubings could be incorporated onto the valve body  125 , depending upon the type of instrument receiving the transferred mixed material.  
         [0090]     G. The Measuring Device  
         [0091]     The measuring device  24  (see  FIG. 1A ) is used to measure components before placing the components into the receptacle for mixing. The measuring device  24  may be of a fixed size, such as a 10 cc measuring cup, may be graduated, and/or may include a sieve for sifting particles before mixing.  
         [0092]     H. The Funnel  
         [0093]     The funnel  10  is used to facilitate placing or pouring of the components to be mixed into the receptacle  12  (see  FIG. 1B ).  
         [0000]     II. Illustrative Use of the System  
         [0094]     In the embodiment shown in  FIG. 1A , the receptacle  12 , stand  14 , mixing element  16 , actuator  18 , plunger  20 , dispenser  22  and the measuring device  24 , as well as the components to be mixed, are gathered together for use, or are withdrawn as needed from the kit  200 . The physician or an assistant inserts the distal end  32  of the receptacle  12  into the neck  44  of the upper side  40  of the stand  14  (see  FIG. 10 ). Desirably, the distal tip  34  of the receptacle  12  is held within the small chamber  46  located on the upper side  40  of the stand  14 , desirably sealing the distal tip  34  closed.  
         [0095]     As  FIG. 20  shows, the physician may use the measuring device  24  to measure a component to be mixed, such as a powdered component for poly(methyl methacrylate) bone cement. The powdered component is poured into the receptacle  12 . If the receptacle  12  bears a graduated scale  39  on its outer surface  33 , the component can be added to the receptacle  12  until the desired level is reached. After the powdered component is added to the receptacle  12 , another component, such as a liquid monomer for bone cement, is added.  
         [0096]     The mixing element  16  and actuator  18  are then obtained. Desirably, the proximal end  56  of the mixing element  16  has been inserted into the slot  96  located on the exterior side  78  of the lower half  74  of the actuator  18  (as  FIG. 11  shows). The assembly is now inverted and the distal end  57  of the mixing element  16  inserted into the proximal end  30  of the receptacle  12  (shown in exploded view in  FIG. 12 ). Desirably, the mixing element  16  is inserted such that the distal tip  62  of the mixing element  16  extends into the distal tip  34  of the receptacle  12 . The actuator  18  desirably engages with the tabs  36  located on the proximal end  30  of the receptacle  12 , so that the lower half  74  of the actuator  18  remains stationary relative to the receptacle  12 .  
         [0097]     The physician now grasps the upper half  72  of the actuator  18  with one hand, while holding the stand  14 , the receptacle  12  or the stand  14  and receptacle  12 , with the other hand (see  FIG. 13 ). The upper half  72  of the actuator  18  is then rotated back and forth, first clockwise and then counterclockwise, e.g. (or vice versa), by half-turns, relative to the receptacle  12 . Alternatively, or in conjunction with this back and forth motion, the actuator  18  may be rotated in a single direction. Desirably, the actuator  18  is rotated enough times to adequately mix the mixture.  
         [0098]     After the mixture is adequately mixed, the actuator  18  and mixing element  16  are removed from the receptacle  12  and set aside. If desired, the mixing element  16  may be scraped against the top of the receptacle  12  to remove mixture clinging to the element  16 , desirably returning such mixture to the receptacle  12 . Next, the plunger  20  is inserted into the proximal end  30  of the receptacle  12  (see  FIG. 14 ). The assembly can now be safely inverted and the stand  14  removed from receptacle  12  (see  FIG. 15 ). Desirably, the stand  14  will not be removed from the receptacle  12  before the step of inserting the plunger  20  and inverting the assembly. In such a case, the mixture, as in the case of a bone filling mixture, could easily flow out of the opening in the distal tip  34  of the receptacle  12 .  
         [0099]     After the stand  14  is removed from the receptacle  12 , air can be expelled from the distal tip  34  of the receptacle  12  by advancing the plunger  20  in the usual fashion of purging air from a syringe. The mixture may be dispensed directly from the receptacle  12  by advancing the plunger  20 . If desired, a dispenser  22  is fitted onto the distal tip  34  of the receptacle  12 . In one embodiment, if the dispenser  22  is a nozzle  100 , the mixture is dispensed through the nozzle  100 . In another embodiment, if the distal tip  34  of the receptacle  12  incorporates a LUER® fitting, the LUER® fitting may mate with a bone filler device as disclosed in U.S. Pat. No. 6,241,734 (which is incorporated herein by reference). When the LUER® fitting is incorporated into the distal tip  34  of the receptacle  12 , the combination allows for the direct filling of multiple bone filler devices. In another embodiment, if the distal tip  34  of the receptacle  12  incorporates a fitting that mates with a syringe body of a 5 cc or 10 cc syringe, the syringe may be filled with the mixture in the receptacle  12 . In another embodiment, the distal tip  34  of the receptacle  12  may incorporate tubing which fits within a 5 cc or 10 cc syringe body, thus allowing the syringe to be back-filled from the plunger end. In such an embodiment, the tubing is inserted through the plunger opening of the syringe. The syringe is filled from its distal tip to its proximal end, the tubing being withdrawn as the syringe fills to a desired level.  
         [0100]     The system shown in  FIG. 1B  contains additional features with enhanced ease of use and fewer steps. The receptacle  20  is packaged in the kit  200  with the dispensing element  22  in the closed position. After gathering the system parts (receptacle  12 , mixing element  16 , actuator  18 , plunger  20  and funnel  10 ) from the sealed kit  200  as well as the material to be mixed, the physician or an assistant positions the funnel  10  within the proximal end  30  of the receptacle  12  and pours the powdered component into the receptacle  12 . If desired, additional powdered materials, such as sterile barium sulfate (to make the mixture radiopaque) or antibiotics (to prevent infection) may be added to the receptacle  12  before addition of the liquid monomer. The mixing element  16  and actuator  18  are coupled together as previously described and inserted into the receptacle  12 . The actuator  18  is positioned to engage with the tabs  36  on the proximal end  30  of the receptacle  12 . The physician or an assistant now rotates the actuator  18  to mix the material as previously described. The monomer fumes in the receptacle  12  may be desirably evacuated from the receptacle  12  by the vacuum hose attachment  31 . After the mixture is adequately mixed, the actuator  18  and mixing element  16  are removed from the receptacle  12  and set aside. Next, the plunger  20  is inserted into the proximal end  30  of the receptacle  12 . Air can be automatically purged from the system through the openings  103  in the plunger  20 . The residual air/monomer mixture may then be evacuated from the interior bore  37  of the receptacle  12  by the vacuum hose attachment  31 , further reducing exposure of the physician or an assistant to the monomer fumes. The mixture is now ready to be transferred. Desirably, the mixed material is transferred directly to the bone filler device as disclosed in U.S. Pat. No. 6,241,734. This step eliminates the need for transferring the material to another device, such as a syringe, which would in turn be used to fill the device of U.S. Pat. No. 6,241,734. The mixture may be dispensed directly through the opened dispensing element  22  by pushing down on the plunger  20 . Alternatively, the flow of the mixture may be controlled by rotating the dispensing handles  123  to open and close the stopcock valve (not shown).  
         [0101]     If a mixture of additional bone filler material is desired, or additional bone filler material is required after the initial mixture has hardened and/or become unusable, the used mixing element  16  (having bone filler material thereon) may be removed from the actuator  18  and replaced with a new mixing element  16 , allowing the actuator  18  to be used to mix an additional batch of bone filler material. In such a case, the kit  200  could contain a single actuator  18  and measuring device  24 , with multiple receptacles  12 , stands  14 , mixing elements  16 , plungers  20  and dispensing elements  22  to allow mixing of multiple batches of bone filler material.  
         [0000]     III. Closed Cement Mixing and Transfer System  
         [0102]     Where the release of fumes and/or vapors from a surgical material is undesirable for some reason, it may be advantageous to use a closed mixing and transfer system for the preparation and/or delivery of medical materials such as bone cement. For example, the fumes and/or vapors from the liquid monomer component of PMMA bone cements can have a very unpleasant smells and inhalation of these fumes may pose a significant health risk to various operating room personnel as well as the patient.  
         [0103]     In the case of bone cement comprising PMMA powder and liquid monomer components, the liquid monomer is typically sealed within a glass jar or ampoule prior to use while the powder is contained in a plastic bag. One example of such packaging is found with SimplexP® PMMA bone cement, commercially available from Howmedica Corporation. While the powdered component of such bone cement is generally inert and not prone to becoming airborne (unless sufficiently disturbed), the liquid monomer component has a very low vapor pressure and vaporizes readily in contact with air.  
         [0104]     Once a glass ampoule containing liquid monomer is opened (typically by breaking the frangible cap on the glass ampoule) the liquid monomer is exposed to the atmosphere and begins to vaporize immediately. Moreover, during the mixing process, the liquid monomer continues to vaporize and also outgasses from the liquid/powder mixture. Once mixing is completed, the monomer continues to outgas from the liquid/powdered mixture, until such time as the mixture is contained within an enclosed environment (such as a syringe or other closed dispensing device or when the mixture is placed within the patient&#39;s body). Unless the mixture is contained within an enclosed environment during substantially all of the steps of the mixing and delivery operation, therefore, a significant amount of vaporized monomer may be released to the operating room during mixing and dispensing of bone cement.  
         [0105]      FIGS. 22 and 23  depict an alternate embodiment of a cement mixing and transfer system which desirably minimizes the release of vaporized monomer to the operating room environment. In this embodiment, the receptacle  12  incorporates a monomer dispensing body  400 . The monomer dispensing body  400  comprises a retaining clip  405 , a containment tube  410 , a breaking element  415 , a cap  420 , a supply lumen  425  and a vent lumen  430 . Desirably, the dispensing body is secured to the receptacle  12 , with the supply lumen  425  and vent lumen  430  communicating with the interior of the receptacle  12  through one or more openings (not shown) in the receptacle wall. The dispensing body  400  may be secured to the receptacle in various ways, including clips, adhesive, welding or by other methods known in the art.  
         [0106]     As shown in  FIG. 23 , a stationary seal  448  desirably engages the upper opening of the receptacle  12  in an air-tight fashion, desirably sealing the receptacle  12  from the operating room environment. A sliding seal  450  is desirably positioned below the stationary seal  448  and within the receptacle  12 . These seals  448  and  450  can comprise various known sealing materials, including latex rubber. Desirably, the seals  448  will permit rotation of the mixing element  16  and axle  87  while maintaining a substantially air-tight seal between the receptacle contents and the atmosphere. In addition, the sliding seal  450  can desirably be moved longitudinally within the receptacle  12 . If desired, the sliding seal can incorporate an internal slot or opening (not shown), which permits the sliding seal  450  to slide along the central axis of the mixing element  16  while maintaining a substantially air-tight seal with the mixing element  16 .  
         [0107]     To prepare the bone cement mixture, a measured amount of powdered PMMA component is introduced into the receptacle  12 . The mixing element and actuator are then attached to the receptacle, with the seals  448  and  450  sealingly engaging the receptacle  12 . A sealed glass ampoule  435  containing liquid monomer is inserted into the containment tube  410 . The cap  420  is placed on the tube  410 , sealing the containment tube closed.  
         [0108]     The cap  420  is then tightened onto the ampoule  435 , desirably forcing the ampoule  435  against the breaking element  415  and fracturing the ampoule  435 . Liquid monomer will desirably flow into the containment tube, through the supply lumen  425  and into contact with the powdered component within the receptacle  12 . The vent lumen  425  will desirably relieve any vacuum which could be formed in the containment tube.  
         [0109]     The liquid and powdered components are now mixed in the manner previously described. Once mixing is completed, a plunger  460  can be inserted through openings (not shown) in the actuator  18  and stationary seal  448  whereby the sliding seal  450  can be advanced towards the mixture within the receptacle  12 . If desired, the sliding seal  450  can incorporate a labyrinth seal or other arrangement which permits air to flow past the sliding seal. Desirably, any air and/or vaporized monomer which flows past the sliding seal  450  will be contained by the stationary seal  448 . Once in contact with the PMMA mixture, the sliding seal  450  will desirably pressurize the mixture, which can then be dispenses in the previously described manner.  
         [0110]     With this embodiment, the PMMA mixture can be dispensed from the mixing and dispensing system without significant release of monomer fumes. Once dispensing is complete, the entire closed system may be disposed of safely.  
         [0111]      FIGS. 24A, 24B ,  25  and  26  depict various embodiments of mixing elements useful in conjunction with the previously-described closed mixing and transfer system. These mixing elements are particularly well suited to collapse and/or folding after mixing has been completed to facilitate advancement of the sliding seal  450  and dispensing of the PMMA mixture. More specifically,  FIGS. 24A and 24B  depict views of a mixing element  16  comprising a series of sections  460  which mix the PMMA components in response to rotation of the mixing element but, when compressed, desirably fold in an accordion-like fashion to allow advancement of the sliding seal  450  and dispensing of the PMMA mixture.  FIG. 25  depicts a mixing element  16  comprising a helical section which mixes the PMMA components in response to rotation of the mixing element  16  but, when compressed, desirably compresses in a spring-like fashion to permit advancement of the sliding seal  450  and dispensing of the PMMA mixture.  FIG. 26  depicts a mixing element  16  comprising a plurality of helical sections which operate in a similar fashion.  
         [0112]     The features of the invention are set forth in the following claims.