Special receptacle or package – For mixing – Means to manipulate without rupture
Reexamination Certificate
2000-03-14
2001-09-11
Fidei, David T. (Department: 3728)
Special receptacle or package
For mixing
Means to manipulate without rupture
C206S219000, C206S524800
Reexamination Certificate
active
06286670
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a process and a device for producing a mixed compound such as a sterile-packed bone cement and more particularly to a process and a device in which employs a barrier to eliminate or substantially reduce the amount of a liquid component of the compound that is drawn into a vacuum chamber.
BACKGROUND OF THE INVENTION
Background Art
The natural joints in the human body are often subject to degenerative changes resulting, inter alia, from disease or trauma. If these defects have progressed too far so as to be irreversible and untreatable, it is necessary to replace the natural joints or bones by corresponding implants. Examples of bone replacement materials that may be mentioned are shaped implants of a wide variety of kinds. For implementation, these bone replacement materials may be anchored in the natural bone using bone cements.
Customary bone cements are composed of a solid component, which consists of a finely divided acrylic polymer and of further additives, such as polymerization initiators, together if desired, with X-ray contrast media and colorants, and of a liquid component, which consists of an acrylic monomer and of further additives such as polymerization accelerators and stabilizers. The polymer powder component of cement consists preferably of granular particles with a spherical shape. The particle size preferably lies within a narrow range or is substantially uniform.
A device for combining the polymer powder and the liquid monomer in a sterile manner is disclosed in commonly assigned U.S. Pat. No. 5,370,221 entitled “Flexible Package for Bone Cement Components”, the disclosure of which is hereby incorporated by reference as if fully set forth herein. In one embodiment, the device has a first chamber for the liquid monomer, a second chamber for the powdered polymer, a removable barrier between the first and second chambers, a vacuum chamber, and a filter. The vacuum chamber of this device is in fluid connection with the second chamber; the filter prevents the powdered polymer from entering the vacuum chamber. Removal of the barrier permits fluid communication between the first and second chambers. The vacuum in the vacuum chamber draws the liquid monomer through the powdered polymer, permitting the two components to be precisely mixed at a predetermined ratio in a sterile environment. While this device made a significant advance in the provision of sterile bone cements, further improvement in the area of vacuum mixing is desirable.
For example, in situations where the vacuum mixing devices have been stored for a large period of time, it has been demonstrated that the vacuum level in the vacuum chamber of some of these devices tends to decrease over a period of time. When vacuum mixing devices that have been stored for long periods of time are used, the vacuum chamber may not have a sufficient level of vacuum to cause the liquid monomer to fully wet all of the powdered polymer. In such cases, it is then necessary to manually mix the components by kneading the material in the container.
One solution suggested to increase the shelf life of the device relates to an increased amount of vacuum by either enlarging the vacuum chamber or increasing the magnitude of the vacuum. However, if the level of vacuum is too great, a portion of the liquid monomer tends to be drawn completely through the powdered polymer and into the vacuum reservoir. In such situations, the powdered polymer and the liquid monomer are not mixed at their proper ratio.
SUMMARY OF THE INVENTION
A general object of the present invention is to provide a container for a mixing a compound having a liquid component utilizing differential pressure.
A more specific object of the present invention is to provide a device for producing a sterile-packed bone cement which utilizes differential pressure to mix a liquid monomer and a solid polymer and which has a relatively long shelf life.
It is another object of the present invention to provide a device for producing a sterile-packed bone cement which utilizes a barrier to permit passage of a gas but resist infiltration of a liquid component of the bone cement into the vacuum chamber.
It is a further object of the present invention to provide a method for producing a sterile-packed bone cement which utilizes differential pressure to mix a liquid monomer and a solid polymer and which has a relatively long shelf life.
In one form, the present invention provides a container for first and second components that are to be mixed within the container with the container including:
a divider for dividing the container into first and second compartments for isolating the first component from the second compartment, the first compartment containing the liquid component and the second compartment containing the powder component;
a vacuum source in fluid communication with the second compartment, the vacuum source being of sufficient size to draw the first component through the second component to thereby ensure thorough admixing of the first and second components after the integrity of the divider is compromised; and
a barrier mechanism disposed between the second compartment and the vacuum reservoir, the barrier mechanism forming a barrier that permits passage of a gas but resists infiltration of the first component into the vacuum source.
In a more specific form, the present invention provides a device for producing a sterile-packed bone cement having a relatively long shelf life, which comprises:
a divider for dividing the container into first and second compartments for isolating the components from one another, the first compartment containing the liquid component and the second compartment containing the powder component;
a vacuum source in fluid communication with the second compartment, the vacuum source being of sufficient size to ensure take up of substantially all residual interstitial gasses to thereby ensure thorough admixing of the liquid and powder components after the integrity of the divider is compromised; and
a barrier mechanism disposed between the second compartment and the vacuum source, the barrier mechanism forming a barrier to resist infiltration of the liquid component into the vacuum source but permit passage of a gas.
In yet another form, the present invention provides a method for forming bone cement comprising the steps of:
providing a container having first and second compartments and a vacuum chamber, the first compartment being filled with a liquid component, the second compartment being filled with powder component and isolated from the first compartment, the vacuum chamber having a negative pressure and being in fluid communication with the second compartment;
causing the first and second compartments to be in fluid communication with one another to thereby permit the vacuum chamber to draw the liquid component into the second chamber;
interposing a barrier mechanism having a gas permeable barrier between the vacuum chamber and the second compartment, the gas permeable barrier resisting penetration by the liquid component; and
admixing the liquid component and powder component under vacuum pressure.
REFERENCES:
patent: 5333736 (1994-08-01), Kawamura
patent: 5370221 (1994-12-01), Magnusson et al.
patent: 5398483 (1995-03-01), Smith et al.
patent: 5588745 (1996-12-01), Tanaka et al.
patent: 5788078 (1998-08-01), Fuss
patent: 5951160 (1999-09-01), Ronk
patent: 5997544 (1999-12-01), Nies et al.
Biomet Inc.
Fidei David T.
Harness & Dickey & Pierce P.L.C.
LandOfFree
Method and apparatus for mixing a compound utilizing a gas... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for mixing a compound utilizing a gas..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for mixing a compound utilizing a gas... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2496160