Mixing device for bone cement and method for mixing bone cement

Abstract

A mixing device for bone cement is provided. The mixing device includes a mixing handle, an housing, and a mixing paddle. The mixing handle having a rod, where at least portions of the rod are in tubular form with monomer inside of the rod. The housing has a mixing chamber in which the monomer and a powder are miscible. The mixing paddle is arranged in the mixing chamber and is movable via the rod.

Claims

1. A mixing device for bone cement, comprising: a tubular rod, the tubular rod having a first end and a second end opposite the first end; a manipulation handle at the first end of the tubular rod; a monomer container situated in the tubular rod for containing a monomer, wherein the monomer container is constructed of a plastic material with a diffusion barrier layer; a housing with a mixing chamber for containing a bone cement powder; a mixing paddle arranged in the mixing chamber, the mixing paddle being connected with the tubular rod at the second end; a piston in the mixing chamber that is moveable away from the mixing paddle to generate a vacuum in the mixing chamber; and a threaded spindle that cooperates with and moves the piston, wherein the mixing chamber takes the shape of a cylinder.

2. The mixing device as claimed in claim 1, wherein the monomer container takes the form of an insertion hose within the tubular rod.

3. The mixing device as claimed in claim 1, wherein the threaded spindle includes a rotary handle that cooperates with a threaded rod connected to the piston, and wherein rotation of the rotary handle imparts translational movement to the threaded rod and the piston.

4. The mixing device as claimed in claim 1, wherein the mixing paddle is arranged at the side of the housing opposite the piston.

5. The mixing device as claimed in claim 4, wherein the tubular rod has at least one predetermined breaking point.

6. The mixing device as claimed in claim 1, wherein the piston has a stroke that is dimensioned such that a residual pressure from 50 to 300 mbar is generated.

7. The mixing device as claimed in claim 1, wherein the piston is further movable toward the tubular rod for pressing out the bone cement.

8. The mixing device as claimed in claim 1, wherein said manipulation handle is detachable.

9. A mixing device for bone cement, comprising: a tubular rod, the tubular rod having a first end and a second end opposite the first end; a manipulation handle at the first end of the tubular rod; a monomer container situated in the tubular rod for containing a monomer, wherein the monomer container is constructed of a plastic material having a diffusion barrier layer; a housing having a mixing chamber for containing a bone cement powder; a mixing paddle arranged in the mixing chamber, the mixing paddle being connected to the tubular rod at the second end; a piston in the mixing chamber that is moveable away from the mixing paddle to generate a vacuum in the mixing chamber; and a spring that is connected to and imparts movement to the piston, wherein the mixing chamber takes the shape of a cylinder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described in detail with reference to exemplary embodiments schematically illustrated in FIGS. 1 through 9, wherein:

(2) FIG. 1 is a schematic view of a mixing device;

(3) FIG. 2 is a partially cutaway view of the mixing device illustrated in FIG. 1;

(4) FIG. 3 is a detailed view of a piston with threaded rod;

(5) FIG. 4 shows a rod for moving the mixing paddle;

(6) FIG. 5 shows one embodiment of a mixing paddle;

(7) FIGS. 6 through 8 show alternative embodiments of a mixing paddle; and

(8) FIG. 9 illustrates a monomer container.

DETAILED DESCRIPTION OF THE DRAWINGS

(9) Referring to FIG. 1, the essential components of a bone cement mixing device 1 will be described in detail with reference to a schematically illustrated exemplary embodiment.

(10) Mixing device 1 comprises a substantially cylindrically shaped housing 2 which includes the mixing chamber for mixing the bone cement (not shown).

(11) On the upper side a manipulation handle 3 can be seen which is connected to a mixing paddle (not shown) via a rod 4 which is guided in housing 2.

(12) On the lower side, a rotary handle 5 is arranged.

(13) For mixing and applying the bone cement, the user (not shown) first rotates rotary handle 5, in this embodiment in counter-clockwise direction. Upon reaching an end position of rotary handle 5, the user, via manipulation handle 3, manipulates the mixing paddle and moves it from top to bottom in order to mix the bone cement. Upon initial actuation, the monomer container (not shown) is opened automatically, so that the bone cement is mixed by further movement of manipulation handle 3.

(14) Then the user breaks off manipulation handle 3.

(15) The remaining portion of rod 4 is formed as some type of a tube or transfer hose.

(16) Then the user turns handle 5 in the opposite direction, and the bone cement exits rod 4 and can be applied.

(17) FIG. 2 shows a partially cutaway view of the mixing device illustrated in FIG. 1. In particular the mixing chamber 10 can be seen, which may be pre-filled with bone cement powder (not shown). Mixing chamber 10 is formed as a cylinder in which a piston 8 is guided which is connected to a threaded rod 9.

(18) Rotary handle 5 is rotatably mounted to housing 2. In this exemplary embodiment, rotary handle 5 encloses the lower portion of the housing, whereby a particularly large gripping surface can be provided while virtually maintaining the dimensions.

(19) At its lower side rotary handle 5 comprises a spindle nut which cooperates with threaded rod 9. Rotary handle 5 and threaded rod 9 thus form a threaded spindle by means of which the rotational movement of rotary handle 5 is convertible into a translational movement of the threaded rod and thus of piston 8.

(20) By retracting piston 8, first a vacuum can be produced in mixing chamber 10.

(21) Opposite the piston, on the other side of housing 2, a mixing paddle 7 is guided by means of rod 4, which mixing paddle may be moved up and down by means of manipulation handle 3. When mixing paddle 7 is actuated for a first time mixing paddle 7 abuts against piston 8 which is equipped with a spike 12.

(22) Spike 12 which is disposed at the head of piston 8 thereby opens a container (not shown) which is filled with the monomer and disposed inside rod 4, whereby the monomer enters mixing chamber 10.

(23) By further manipulating mixing paddle 7, the bone cement powder and monomer are mixed to form bone cement.

(24) Subsequently, the user completely pulls up manipulation handle 3 and breaks off manipulation handle 3 at predetermined breaking point 17 provided on the rod. Rod 4 is formed as a tube, at least up to predetermined breaking point 17, and is used as a transfer hose when manipulation handle 3 has been broken off.

(25) By rotating rotary handle 5 in the opposite direction, piston 8 moves upwardly and drives the mixed bone cement upwards, through the tubular portion of rod 4.

(26) FIG. 3 illustrates piston 8 and threaded rod 9.

(27) Piston 8 and threaded rod 9 may be of one-piece construction formed from plastics.

(28) Piston 8 has a spike 12 on piston head 13, which in a preferred embodiment of the invention is formed as an embedded metal part.

(29) Piston 8 has a groove 14 which may for example serve to receive an elastomeric gasket.

(30) Furthermore, the piston comprises a spaced guide plate 15 which reduces the risk of canting piston 8.

(31) Threaded rod 9 has a relatively steep thread which in this exemplary embodiment has a pitch from 1.5 to 2.5 cm. Thus, piston 8 may be moved up and down in the mixing chamber with only a few rotations. At the same time it may be ensured by a suitable pitch of the thread of threaded rod 9 that the user notices when the bone cement has already solidified too much. In this case moving up the piston would be so difficult that it is recognizable when turning the rotary handle (5 in FIG. 1).

(32) FIG. 4 shows a detailed view of rod 4 by which the mixing paddle (not shown) is moved.

(33) The mixing paddle is attached to the lower end of rod 4, and the manipulation handle at the upper end thereof.

(34) Rod 4 is formed as a tube into which a monomer container may be inserted.

(35) In this exemplary embodiment, the position of the monomer container is represented by dashed line 20.

(36) In this embodiment, the lower portion 19 of the rod has a smaller diameter than the upper portion 18 of the rod. The monomer container may for example come to rest against the collar formed between the two portions.

(37) Tubular rod 4 has a lower predetermined breaking point 16 and an upper predetermined breaking point 17. Thus, rod 4 which at the same time serves as a transfer hose, may have a different length, depending on the application. The monomer container arranged inside rod 4, by contrast, has no predetermined breaking point but is firmly connected to manipulation handle 3 (not shown). After breaking off the manipulation handle at predetermined breaking point 16 or 17, the monomer container is pulled out from rod 4, and there are no remains of the monomer container left which could impede the exit of the mixed bone cement.

(38) FIG. 5 schematically illustrates a mixing paddle 7.

(39) The mixing paddle may take almost any form. In this exemplary embodiment, the mixing paddle comprises a ring 21 which is connected to an inner ring 29 by webs 23. Inner ring 29 is mounted around the actuating rod (4 in FIG. 2). Recesses 22 are formed between the webs through which the bone cement may flow back and forth past webs 23 and is mixed in this manner.

(40) FIGS. 6 through 8 show alternative embodiments of a mixing paddle.

(41) The mixing paddle illustrated in FIG. 6 has slanted wings to generate a turbulent flow and thus achieve better mixing.

(42) The mixing paddle shown in FIG. 7 is formed similarly and additionally has an outer ring 21 which prevents inhomogeneously mixed residues from being formed at the wall of the mixing chamber.

(43) FIG. 8 shows another embodiment of a mixing paddle 7 which comprises an upper 24 and a lower 25 plate. The bone cement may flow through the gaps formed between the plates. This embodiment of the invention especially permits rapid mixing of the bone cement without any rotational movement.

(44) FIG. 9 shows a view of a detail of monomer container 27, only the head of monomer container 27 being shown in this detailed view.

(45) The walls of container 27 may be made from plastics or aluminum. Monomer container 27 is closed by a lid 28. This may be screwed-on lid, for example, or as in this exemplary embodiment a pressed-on aluminum lid, or a plastic lid, for example made of PTFE, which engages monomer container 27 and is suitable sealed. To extract the monomer, the lid 28 may be perforated with a pointed object, for example by the spike on the piston shown in FIG. 3, whereby the monomer exits. To permit the monomer to exit from the otherwise closed monomer container 27, monomer container 27 is partially filled with a gas volume which due to the pressure difference under applied vacuum displaces the monomer (not shown).

(46) The invention provides for particularly simple and safe mixing of bone cement.

(47) It will be appreciated that the invention is not limited to one combination of the features described above, rather a person skilled in the art will use any features as far as reasonable in any combination.

LIST OF REFERENCE NUMERALS

(48) 1 Mixing device

(49) 2 Housing

(50) 3 Manipulation handle

(51) 4 Rod

(52) 5 Rotary handle

(53) 6 Upper housing part

(54) 7 Mixing paddle

(55) 8 Piston

(56) 9 Threaded rod

(57) 10 Mixing chamber

(58) 11 Spindle nut

(59) 12 Spike

(60) 13 Piston head

(61) 14 Groove

(62) 15 Guide plate

(63) 16 Predetermined breaking point

(64) 17 Predetermined breaking point

(65) 18 Upper portion

(66) 19 Lower portion

(67) 20 Dashed line

(68) 21 Ring

(69) 22 Recess

(70) 23 Web

(71) 24 Upper plate

(72) 25 Lower plate

(73) 27 Monomer container

(74) 28 Lid

(75) 29 Inner Ring