Methods and apparatus for mixing bone cement components using an evacuated mixing chamber

• US 5,588,745 A
• Filed: 09/02/1994
• Issued: 12/31/1996
• Est. Priority Date: 09/02/1994
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Howmedica (Stryker Corporation)
• Inventors: Chochinov, Allan B., Tanaka, Kazuna, Kapec, Jeffrey
• Primary Examiner(s): Cooley, Charles E.
• Application Number:
  US08/300,045
• Time in Patent Office: 851 Days
• Field of Search: 366/129, 366/130, 366/139, 366/178.1, 366/163.1, 366/167.1, 366/169.1, 366/169.2, 366/182.1, 366/184, 366/189, 366/194-196, 366/308, 366/178.2, 206/219, 206/222, 604/410, 604/411, 604/413-416, 604/903, 606/86, 606/92-94
• US Class Current: 366/130
• CPC Class Codes: A61B 17/8827 with filtering, degassing, venting or pressure relief means
• CPC Class Codes: A61B 17/8833 Osteosynthesis tools specially adapted for handling bone cement or fluid fillers; Means for supplying bone cement or fluid fillers to introducing tools, e.g. cartridge handling 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 33/5011 portable during use, e.g. hand-held
• CPC Class Codes: B01F 35/562 the mixer or mixing elements being collapsible, i.e. when discharging the products
• CPC Class Codes: B01F 35/713 comprising breaking packages or parts thereof, e.g. piercing or opening sealing elements between compartments or cartridges containers or packages per se B65D
• CPC Class Codes: B01F 35/7137 Piercing, perforating or melting membranes or closures which seal the compartments
• CPC Class Codes: B01F 35/7161 the containers being connected coaxially before contacting the contents
• CPC Class Codes: B01F 35/718 using vacuum, under pressure in a closed receptacle or circuit system
• CPC Class Codes: B01F 35/75 Discharge mechanisms
• CPC Class Codes: B01F 35/75425 using pistons or plungers

Abstract

Methods and apparatus are set forth for preparing and delivering bone cement formed by combining a powdered polymer component and a liquid monomer component. The powdered polymer component is stored in an evacuated mixing chamber. The liquid monomer component, according to one specific aspect of the invention, is introduced into the mixing chamber by a control mechanism which causes the stored powder to be "substantially wet", i.e., all of the powdered polymer component is wet to at least some degree and is otherwise devoid of powder pockets. The control mechanism, according to a preferred embodiment of the invention, stages the release of the liquid monomer into the vacuum packed powder chamber, under the effect of the vacuum, in a timed sequence using a plurality of monomer distribution channels. The distribution channels, which in a preferred embodiment of the invention include liquid component diffusers, insure the substantial wetting of the stored powder by delivering the liquid in parallel to different portions of the mixing chamber. The substantial wetting of the powder is designed to ultimately insure a homogeneous bone cement mix.

Claims

1. A method for preparing and delivering self curing bone cement mixture formed by combining a mass of powdered polymer component and a liquid monomer component, comprising the steps of:

(a) storing said powdered polymer component pass in an evacuated mixing chamber;

(b) storing said liquid monomer component in a separate pressurized component chamber; and

(c) controlling the introduction of said liquid monomer component into said mixing chamber, including the step of wetting said powdered polymer component from outside and from within the stored powdered polymer component mass to thereby substantially wet the powdered polymer component mass stored in said mixing chamber.

2. A method as set forth in claim 1 wherein said step of controlling further comprises the step of delivering said liquid monomer in parallel to a multiplicity of different locations within said mixing chamber, including at least one location within the powdered polymer component mass stored in said mixing chamber.

3. A method as set forth in claim 1 wherein said step of controlling further comprises the step of utilizing a plurality of monomer distribution channels terminating in said mixing chamber to deliver said liquid monomer component thereto.

4. A method as set forth in claim 3 wherein said plurality of monomer distribution channels insure the distribution of said liquid monomer component to at least the center and periphery of said evacuated mixing chamber.

5. A method as set forth in claim 3 further comprising the step of utilizing one way monomer distribution channels to thereby allow the liquid monomer component to flow only towards and into said mixing chamber.

6. A method as set forth in claim 1 wherein said step of controlling further comprises the steps of:

(a) opening said separate pressurized chamber; and

(b) placing the liquid monomer component of said separate pressurized chamber in fluid communication with the powdered polymer component mass of said mixing chamber at a multiplicity of different locations therein.

7. A method as set forth in claim 6 wherein said step of placing further comprises the step of utilizing a plurality of monomer distribution channels, each including liquid component diffusion means terminating in said mixing chamber, to deliver said liquid monomer component to said mixing chamber.

8. A method as set forth in claim 7 wherein said step of opening further comprises the step of staging the release of said liquid monomer component into said mixing chamber.

9. A method as set forth in claim 8 wherein said step of staging further comprises the step of utilizing the combination of timing step means, seal piercing means and said liquid component diffusion means to stage the release of said liquid monomer component into said mixing chamber in a timed sequence.

10. A method as set forth in claim 9 wherein said combination is operative to first break a seal on said separate pressurized component chamber and then break a seal on said evacuated mixing chamber to thereby enable said liquid monomer component to be drawn from said separate pressurized component chamber, through said plurality of monomer distribution channels, into said evacuated mixing chamber via said liquid component diffusion means.

11. A method as set forth in claim 10 further comprising the step of preventing component and mixture backflow.

12. A method as set forth in claim 1 further comprising the step of stirring the liquid monomer component and powdered polymer component mass together after the liquid monomer component has been introduced into said mixing chamber.

13. A method as set forth in claim 1 further comprising the step of shaking the contents of said mixing chamber after the liquid monomer component has been introduced thereto.

14. A method as set forth in claim 1 further comprising the steps of:

(a) stirring the liquid monomer component and powdered polymer component mass together after the liquid monomer component has been introduced into said mixing chamber; and

(b) shaking the contents of said mixing chamber after the liquid monomer component has been introduced thereto.

15. A method as set forth in claim 14 further comprising the step of pressurizing the cement mixture in said mixing chamber to compress air out of said cement mixture.

16. A method as set forth in claim 15 further comprising the step of dispensing the compressed cement mixture from said mixing chamber.

17. A method as set forth in claim 16 wherein said step of dispensing said compressed cement mixture is performed by further pressurizing the mixture in said mixing chamber to break a seal between said mixing chamber and a dispensing nozzle leading out from said mixing chamber.

18. A method for saturating a predetermined mass of a powdered component with a predetermined volume of a liquid component as part of a component mixing process, comprising the steps of:

(a) storing said powdered component mass in an evacuated mixing chamber;

(b) storing said liquid component in a separate pressurized component chamber; and

(c) controlling the introduction of said liquid component into said mixing chamber, including the step of wetting said powdered component mass from outside and from within the stored powdered component mass to thereby substantially wet the powdered component mass stored in said mixing chamber.

19. A method for mixing a powdered component mass with a liquid component comprising the steps of:

(a) evacuating a first container containing a powdered component mass;

(b) providing a second container containing a liquid component;

(c) connecting said first and second containers, after the evacuation of said first container, allowing liquid component to be drawn into said first container; and

(d) introducing said liquid component into said first container in a manner which substantially wets the powdered component mass stored therein by wetting said powdered component mass from outside and from within the stored powdered component mass.

20. A plunger head, for use as part of a system for mixing a powdered component, stored in an evacuated mixing chamber into which the distal end of said plunger head extends, with a liquid component, stored in a pressurized chamber attached to the proximate end of said plunger head, comprising:

(a) means for controlling the introduction of said liquid component stored in said pressurized chamber to a multiplicity of different locations within said evacuated mixing chamber to substantially wet the powdered component stored therein; and

(b) means for uniformly mixing said powdered component and said liquid component within said mixing chamber thereby saturating said powdered component with said liquid component.

21. Apparatus as set forth in claim 20 wherein said means for controlling the introduction of said liquid component into said mixing chamber utilizes the vacuum in said evacuated mixing chamber to draw said liquid component therein.

22. Apparatus as set forth in claim 21 wherein said means for controlling further comprises:

(a) means for opening said separate pressurized chamber; and

(b) means for placing the liquid component of said separate pressurized chamber in fluid communication with the powdered component of said mixing chamber at a multiplicity of different locations therein.

23. Apparatus as set forth in claim 22 wherein said means for placing further comprises a plurality of liquid component distribution channels, each including liquid component diffusion means terminating in said mixing chamber, to deliver said liquid component to said mixing chamber.

24. Apparatus as set forth in claim 23 wherein said means for opening further comprises means for staging the release of said liquid component into said mixing chamber.

25. Apparatus as set forth in claim 24 herein said means for staging further comprises:

(a) timing step means for staging the release of said liquid component into said mixing chamber in a timed sequence; and

(b) seal piercing means cooperating with said timing step means.

26. Apparatus as set forth in claim 23 wherein said means for controlling is operative to first break a seal on said separate pressurized component chamber and then break a seal on said evacuated mixing chamber to thereby enable said liquid component to be drawn from said separate pressurized component chamber, through said plurality of distribution channels, into said evacuated mixing chamber via said liquid component diffusion means.

27. Apparatus as set forth in claim 26 wherein said liquid component diffusion means further comprises:

(a) means for enabling said liquid component to enter said mixing chamber; and

(b) means for preventing said powdered component from inhibiting the flow of said liquid monomer component into said mixing chamber.

28. Apparatus as set forth in claim 27 wherein said liquid component diffusion means further comprises a double screen which includes an outside wire mesh screen portion and an interior slit screen portion, the combination of which allows said liquid component to enter said mixing chamber while preventing said powdered component from inhibiting the flow of said liquid component into said mixing chamber.

29. Apparatus as set forth in claim 28 wherein said powdered component is a polymer used as a component in a bone cement mix.

30. Apparatus as set forth in claim 28 wherein said liquid component is a monomer used as a component in a bone cement mix.

31. Apparatus as set forth in claim 26 wherein said liquid component diffusion means is operative to prevent component and mixture backflow.

32. Apparatus as set forth in claim 31 wherein said liquid component diffusion means further comprises the combination of a wire mesh screen and a slitted plastic tube.

33. Apparatus as set forth in claim 32 wherein said tube is coated with TEFLON™

brand non-stick coating.

34. Apparatus as set forth in claim 20 wherein said means for controlling further comprises a center stem through which said liquid component may be introduced into said evacuated mixing chamber.

35. Apparatus as set forth in claim 34 wherein said means for uniformly mixing further comprises a stirring assembly, combined with said center stem, for stirring said liquid and said powdered component after said liquid component has been introduced into said mixing chamber.

36. Apparatus as set forth in claim 35 wherein said stirring assembly further comprises a "U" shaped rod have a collapsible wire mesh spanning said rod.

37. A mixing device for mixing a powdered and a liquid component comprising:

(a) a first evacuated container containing a powdered component mass;

(b) a second container containing a liquid component;

(c) means for connecting said first and second containers, after the evacuation of said first container, allowing said liquid component to be drawn into said first container, and

(d) means for introducing said liquid component into said first container in a manner which substantially wets the powdered component mass stored therein by wetting said powdered component mass from outside and from within the stored powdered component mass.

38. The mixing device of claim 37 further including means for dispensing said liquid and powdered components which have been mixed.

39. The mixing device of claim 38 wherein said first container is cylindrical in shape and has a first end with a dispensing nozzle and said means for dispensing is a plunger slidably mounted within a second open end of said cylindrical first container.

40. The mixing device as set forth in claim 38 wherein said first container has a breakable seal formed thereon for retaining the evacuated condition thereof.

41. The mixing device as set forth in claim 38 wherein said second container is operative to allow atmospheric pressure to act on the liquid component thereof to force said liquid component into said first container upon the connection of said second container to said evacuated first container.

42. Apparatus for preparing and delivering a self curing bone cement mixture formed as a polymeric reaction product when a powdered polymer component is mixed with a liquid monomer component, comprising:

(a) an evacuated first component chamber for storing said powdered polymer component mass;

(b) a second component chamber for storing said liquid monomer component;

(c) means for controlling the introduction of said liquid monomer component, stored in said second component chamber, to a multiplicity of different locations within said first component chamber, including locations outside and within the stored powdered polymer component mass, to thereby substantially wet the powdered polymer component mass stored in said mixing chamber;

(d) means for uniformly mixing said powdered polymer component mass and said liquid monomer component within said first component chamber thereby saturating said powdered polymer component mass with said liquid monomer component.

43. Apparatus as set forth in claim 42 wherein said means for controlling the introduction of said liquid monomer component into said first component chamber utilizes the vacuum in said first component chamber to draw said liquid monomer component therein.

44. Apparatus as set forth in claim 43 wherein said means for controlling further comprises:

(a) means for opening said second component chamber; and

(b) means for placing the liquid monomer component of said second component chamber in fluid communication with the powdered polymer component mass of said first component chamber at a multiplicity of different locations therein.

45. Apparatus as set forth in claim 44 wherein said means for placing further comprises a plurality of liquid component distribution channels, each including liquid component diffusion means terminating in said first component chamber, to deliver said liquid monomer component to said first component chamber.

46. Apparatus as set forth in claim 45 wherein said means for opening further comprises means for staging the release of said liquid monomer component into said first component chamber.

47. Apparatus as set forth in claim 46 wherein said means for staging further comprises:

(a) timing step means for staging the release of said liquid monomer component into said first component chamber in a timed sequence; and

(b) seal piercing means cooperating with said timing step means.

48. Apparatus as set forth in claim 45 wherein said means for controlling is operative to first break a seal on said second component chamber and then break a seal on said first component chamber to thereby enable said liquid monomer component to be drawn from said second component chamber, through said plurality of distribution channels, into said evacuated first component chamber via said liquid component diffusion means.

49. Apparatus as set forth in claim 48 wherein said liquid component diffusion means further comprises:

(a) means for enabling said liquid monomer component to enter said first component chamber; and

(b) means for preventing said powdered polymer component mass from inhibiting the flow of said liquid monomer component into said first component chamber.

50. Apparatus as set forth in claim 49 wherein said liquid component diffusion means further comprises a double screen which includes an outside wire mesh screen portion and an interior slit screen portion, the combination of which allows said liquid monomer component to enter said first component chamber while preventing said powdered polymer component mass from inhibiting the flow of said liquid monomer component into said first component chamber.

51. Apparatus as set forth in claim 48 wherein said liquid component diffusion means is operative to prevent component and mixture backflow.

52. Apparatus as set forth in claim 51 wherein said liquid component diffusion means further comprises the combination of a wire mesh screen and a slitted plastic tube.

53. Apparatus as set forth in claim 52 wherein said tube is coated with TEFLON™

brand non-stick coating.

54. Apparatus as set forth in claim 42 wherein said means for controlling further comprises a center stem through which said liquid monomer component may be introduced into said evacuated first component chamber.

55. Apparatus as set forth in claim 54 wherein said means for uniformly mixing further comprises a stirring assembly, combined with said center stein, for stirring said liquid monomer and said powdered polymer component mass after said liquid monomer component has been introduced into said first component chamber.

56. Apparatus as set forth in claim 55 wherein said stirring assembly further comprises a "U" shaped rod have a collapsible wire mesh spanning said rod.

57. Apparatus as set forth in claim 54 further comprising means for pressurizing the cement mixture in said first component chamber to compress air out of said cement mixture.

58. Apparatus as set forth in claim 57 further comprising means for dispensing the compressed cement mixture from said first component chamber.

59. Apparatus as set forth in claim 57 wherein said means for dispensing comprises a plunger head that includes said means for controlling and said means for uniformly mixing.

60. Apparatus for preparing a homogeneous self-curing two component powder/liquid bone cement mixture using a vacuum packed powdered polymer chamber containing a powder polymer mass into which liquid monomer is introduced, comprising:

(a) a pressurized chamber for storing said liquid monomer;

(b) a vacuum packed powder chamber for storing said powdered polymer mass; and

(c) means for controlling the introduction of said liquid monomer into said vacuum packed powder chamber to locations outside and within the stored powdered polymer mass, to thereby substantially wet the powdered polymer mass stored therein.

61. Apparatus as set forth on claim 60 wherein said means for controlling further comprises means for delivering said liquid monomer in parallel to a multiplicity of different locations within said powder chamber.

62. Apparatus as set forth in claim 60 wherein said means for controlling further comprises means for delivering said liquid monomer to said powder chamber utilizing a plurality of monomer distribution channels terminating in said powder chamber.

63. Apparatus as set forth in claim 62 wherein said plurality of monomer distribution channels insure the distribution of said liquid monomer to at least the center and periphery of the powder chamber.

64. Apparatus as set forth in claim 62 wherein said plurality of monomer distribution channels are one way channels allowing only the liquid monomer to flow towards and into said powder chamber.

65. Apparatus as set forth in claim 60 wherein said means for controlling further comprises:

(a) means for opening said powder chamber; and

(b) means for placing the liquid monomer of said pressurized chamber in fluid communication with the powdered polymer mass of said powder chamber at a multiplicity of different locations therein.

66. Apparatus as set forth in claim 65 wherein said means for placing utilizes a plurality of monomer distribution channels, each including liquid component diffusion means terminating in said powder chamber, to deliver said liquid monomer to said powder chamber.

67. Apparatus as set forth in claim 66 wherein said means for opening further comprises means for staging the release of said liquid monomer into said powder chamber.

68. Apparatus as set forth in claim 67 wherein said means for staging further comprises the combination of timing step means, seal piercing means and said liquid component diffusion means to stage the release of said liquid monomer into said powder chamber in a timed sequence.

69. Apparatus as set forth in claim 68 wherein said combination is operative to first break a seal on said pressurized chamber and then break a seal on the evacuated powder chamber to thereby enable said liquid monomer to be drawn from said pressurized chamber, through said plurality of monomer distribution channels, into said powder chamber via said liquid component diffusion means.

70. Apparatus as set forth in claim 69 wherein said liquid component diffusion means is operative to prevent component and mixture backflow.

71. Apparatus as set forth in claim 60 further comprising means for stirring the liquid monomer and powdered polymer mass together after the liquid monomer has been introduced into said powder chamber.

72. Apparatus as set forth in claim 60 further comprising:

a) means for stirring the liquid monomer and powdered polymer mass together after the liquid monomer has been introduced into said powder chamber; and

(b) means for pressurizing the cement mixture to compress air out of said mixture.

73. Apparatus for as set forth in claim 72 further comprising means for dispensing the compressed cement mixture.