Bone cement mixing and loading apparatus

• US 5,344,232 A
• Filed: 10/05/1993
• Issued: 09/06/1994
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: Stryker Corporation
• Original Assignee: Stryker Corporation
• Inventors: Nelson, Charles L., Steffler, Michael W., Tyler, Douglas L. Sr.
• Primary Examiner(s): Simone, Timothy F.
• Assistant Examiner(s): Chin, Randall E.
• Application Number:
  US08/132,134
• Time in Patent Office: 336 Days
• Field of Search: 366/131, 366/139, 366/181, 366/184, 366/188, 366/194, 366/195, 366/196, 366/279, 366/309, 366/312, 366/313, 366/326, 366/328, 366/329, 366/349, 141/22, 141/23, 141/26, 141/27, 141/363, 141/375, 141/383
• US Class Current: 366/139
• CPC Class Codes: A61B 17/8822 characterised by means facilitating expulsion of fluid from the introducer, e.g. a screw pump plunger, hydraulic force transmissions, application of vibrations or a vacuum
• CPC Class Codes: A61B 17/8825 characterised by syringe details A61B17/8822, A61B17/8827 take precedence
• CPC Class Codes: A61B 17/8827 with filtering, degassing, venting or pressure relief means
• CPC Class Codes: A61B 2017/8838 for mixing bone cement or fluid fillers
• CPC Class Codes: A61F 2002/4685 by means of vacuum
• CPC Class Codes: B01F 2101/20 Mixing of ingredients for bone cement
• CPC Class Codes: B01F 23/565 by introducing liquids in solid material, e.g. to obtain slurries
• CPC Class Codes: B01F 27/00 Mixers with rotary stirring devices in fixed receptacles magnetic mixers B01F33/45; Kneaders
• CPC Class Codes: B01F 27/112 with arms, paddles, vanes or blades
• CPC Class Codes: B01F 33/5011 portable during use, e.g. hand-held
• CPC Class Codes: B01F 33/5012 adapted to be mounted during use on a standard, base or support
• CPC Class Codes: B01F 33/70 Mixers specially adapted for working at sub- or super-atmospheric pressure, e.g. combined with de-foaming
• CPC Class Codes: B01F 35/3202 Hand driven
• CPC Class Codes: B01F 35/4121 at the top and at the bottom of the receptacle, e.g. for performing a conical orbital movement about a vertical axis
• CPC Class Codes: B01F 35/75 Discharge mechanisms
• CPC Class Codes: B01F 35/751 Discharging by opening a gate, e.g. using discharge paddles
• CPC Class Codes: B01F 35/75415 using gravity
• CPC Class Codes: B01F 35/75455 using a rotary discharge means, e.g. a screw beneath the receptacle B01F35/751 takes precedence

Abstract

An apparatus for mixing bone cement and containing the mixed bone cement preparatory to dispensing. The mixing chamber has an outlet for the mixed cement. A cartridge has an inlet releasably coupled to the outlet of the mixing chamber for receiving mixed bone cement therefrom. Structure is provided for moving cement from an upper region of the mixing chamber down into a lower region thereof to mix same and for moving such mixed cement off an inner surface of the mixing chamber and into the cartridge.

Claims

1. An apparatus for mixing bone cement and containing the mixed bone cement preparatory to dispensing, the apparatus comprising:

a mixing chamber having an outlet for outputting mixed cement

a cartridge having an inlet releasably coupled to the outlet of said mixing chamber for receiving mixed bone cement therefrom;

means for moving cement from an upper region of said mixing chamber down into a lower region thereof to mix same and for moving such mixed cement off an inner surface of said mixing chamber and into said cartridge;

a vacuum shroud surrounding said cartridge and extending up substantially to a bottom end of said mixing chamber, and means for connecting a vacuum source to the interior of said mixing chamber and vacuum shroud to keep said mixing chamber and cartridge at a subatmospheric pressure during cement mixing and loading of the mixed cement into said cartridge.

2. The apparatus of claim 1, in which said connecting means comprises a tube that connects said mixing chamber to said shroud, said tube being tapered and having an opening at the shroud end which is smaller than its opening to the mixing chamber, to allow said mixing chamber and cartridge to fill with air before the shroud.

3. An apparatus for mixing bone cement and containing the mixed bone cement preparatory to dispensing, the apparatus comprising:

a mixing chamber having a top portion and a bottom portion, said bottom portion including an outlet for outputting mixed cement;

a cartridge having a top portion including an inlet releasably coupled to the outlet of said mixing chamber for receiving mixed bone cement therefrom;

means for preventing incorporation of air into the cement mixture comprising a vacuum shroud surrounding the cartridge and extending up substantially to the bottom portion of the mixing chamber and means for connecting a vacuum source to the interior of said mixing chamber and vacuum shroud to keep the mixing chamber and cartridge at a subatmospheric pressure during cement mixing and loading into said cartridge.

4. The apparatus of claim 3, in which said vacuum shroud has a top, said preventing means including means supporting the bottom portion of said mixing chamber on the top of the vacuum shroud with said cartridge extending down into the vacuum shroud and means sealing the vacuum shroud to maintain said subatmospheric pressure in said cartridge.

5. The apparatus of claim 3 in which said vacuum shroud has a top comprising an upward facing and radially outward extending flange, said mixing chamber having a radially outward extending flange at an intermediate height thereon, and sealing means in the form of an annular seal sandwiched between and supporting said mixing chamber flange atop said vacuum shroud flange.

6. The apparatus of claim 5 in which said means for connecting comprises a passage outside said mixing chamber communicating with said vacuum source and a depression in the top of the vacuum shroud flange covered by the mixing chamber flange and extending radially outward from the interior of said vacuum shroud to said outside passage.

7. The apparatus of claim 3 in which said mixing chamber comprises an open topped, downwardly converging funnel with a radially outwardly extending top flange, said mixing chamber further comprising a horizontal lid and an annular seal separating said lid from said top flange and creating a vacuum seal therebetween, said means for connecting to a vacuum source comprising a passage outside said mixing chamber sidewall and opening up through said radially outward extending top flange of said mixing chamber at a location radially inboard of said annular seal, with the top of said passage being spaced below said lid for communication between said passage and the interior of said mixing chamber.

8. The apparatus of claim 7 including means for mixing cement in said mixing chamber and comprising a shaft sealingly and rotatably supported on said lid and extending down into said mixing chamber and having cement engaging means thereon and rotatable therewith for mixing and moving cement.

9. The apparatus of claim 8 in which said shaft is hollow, a push rod sealingly and vertically movable in said hollow shaft, a piston movable down in said cartridge by downward movement of said rod for loading mixed cement from said mixing chamber down into said cartridge.

10. The apparatus of claim 3 including means defining a central opening from said mixing chamber bottom portion to said cartridge top portion, a piston sealingly slidable axially in said cartridge from a normal first position at the bottom portion of said mixing chamber down into said cartridge toward the bottom portion thereof, the bottom portion of the cartridge and the top portion of the mixing chamber being open to the vacuum shroud so as to provide subatmospheric pressure on both sides of the piston.

11. The apparatus of claim 3 including a lid sealingly closing the top portion of said mixing chamber, a vacuum release hole in the lid, a closure normally covering and sealing said hole and being removable to release vacuum from said mixing chamber and vacuum shroud.

12. The apparatus of claim 3 in which said vacuum shroud has a closed bottom portion and a radially outward extending bottom portion for supporting, in a stable manner, said mixing chamber and cartridge in an upright position.

13. An apparatus for mixing bone cement and containing the mixed bone cement preparatory to dispensing, the apparatus comprising:

a mixing chamber having a top portion and a bottom portion, said bottom portion including an outlet for outputting mixed cement;

a cartridge having a top portion and a bottom portion, said top portion including an inlet releasably coupled to the outlet of said mixing chamber for receiving mixed bone cement therefrom;

means defining a central opening from said mixing chamber bottom portion to said cartridge top portion, and a piston sealingly slidable axially in said cartridge from a normal first position sealing the bottom portion of said mixing chamber down to a second position in said cartridge, said piston in said normal first position separating said mixing chamber from said cartridge;

means for maintaining the interior of said mixing chamber and cartridge and central opening at a subatmospheric pressure during cement mixing and loading into said cartridge for preventing incorporation of air into the cement mixture.

14. The apparatus of claim 13 in which said subatmospheric pressure maintaining means comprises a vacuum shroud in subatmospheric communication with said mixing chamber and said cartridge, and in which the bottom portion of said cartridge and the top portion of said mixing chamber are open to said vacuum shroud so as to provide subatmospheric pressure on both sides of the piston.

15. The apparatus of claim 14 in which said piston has a concave, rounded upper end facing up into said mixing chamber and further has an annular leathered perimeter edge upwardly and outwardly angled to resiliently lay against and smoothly continue the side of the inner peripheral surface of the bottom portion of said mixing chamber to provide said mixing chamber with a sealed rounded bottom and wipe sealingly against the inner peripheral surface of said cartridge as said piston is moved downwardly therein for loading, and upwardly therein for unloading, of mixed cement.