Mixing device for bone cement

Abstract

A mixing device for bone cement comprising a plunger for extruding the mixed material, which plunger is also used as a cover. The plunger has spring blades adapted to be latched on a collar of the housing.

Claims

1. A mixing device comprising: a housing having a mixing cavity and a collar, the collar having an inclined surface that merges with a support surface; and a plunger adapted to force out mixed material and operative as a housing cover during mixing of the material to be mixed, the plunger having a plurality of spring blades adapted to engage the support surface of the collar to lock the plunger in a cover position, the spring blades each having a spring portion which is inclined outwards relative to a central axis of the plunger, the plurality of spring blades releasing the plunger upon application of a force on the plunger in a forward direction in which the plunger has to be moved to force out the mixed material, the inclined surface of the collar facilitating resilient inward deflection of the spring blades when the force is applied to the plunger, wherein the inclined surface extends vertically and the support surface extends horizontally.

2. The mixing device as claimed in claim 1 wherein the plunger has at least four of the spring blades.

3. The mixing device as claimed in claim 1, wherein the spring blades are formed integrally with the plunger.

4. The mixing device as claimed in claim 1, wherein in a position in the which the plunger serves as a cover, the spring blades are at least partially latched under a locking hook of the housing while an opposite engagement surface thereof engages on a corresponding support surface of the collar.

5. The mixing device as claimed in claim 4, wherein the locking hook has an inclined sliding surface on its upper side.

6. The mixing device as claimed in claim 1, wherein a rod for moving a mixing paddle is guided in the plunger.

7. The mixing device as claimed in claim 1, wherein the spring blades are L-shaped.

8. The mixing device as claimed in claim 1, wherein the plunger comprises a front portion that has an enlarged diameter with respect to a rearward portion.

9. The mixing device as claimed in claim 1, wherein the mixing device comprises a funnel that can be placed on the housing and which is divided into two areas.

10. The mixing device as claimed in claim 9, wherein the mixing device comprises a detachable bottom which can be replaced by an application tube.

11. The mixing device as claimed in claim 1, wherein the spring portion is inclined relative to the central axis of the plunger at an angle between 10° and 60°.

12. The mixing device as claimed in claim 1, wherein said mixing device is filled with bone cement.

13. The mixing device of claim 1, wherein each of the spring blades further has a hook portion that extends outwardly from an upper end of the spring portion.

14. A mixing device comprising: a housing having a mixing cavity and a collar, the collar having an inclined surface that merges with a support surface; and a plunger adapted to force out mixed material and operative as a housing cover during mixing of the material to be mixed, the plunger having a plurality of spring blades adapted to engage the support surface of the collar to lock the plunger in a cover position, the spring blades each having a spring portion which is inclined outwards relative to a central axis of the plunger, the plurality of spring blades releasing the plunger upon application of a force on the plunger in a forward direction in which the plunger has to be moved to force out the mixed material, the inclined surface of the collar facilitating resilient inward deflection of the spring blades when the force is applied to the plunger, wherein each of the spring blades further has a hook portion that extends outwardly from an upper end of the spring portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject matter of the invention will now be described in more detail below by way of an exemplary embodiment illustrated in the drawings of FIG. 1 to FIG. 11.

(2) FIG. 1 shows an elevational side view of a mixing device.

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

(4) FIG. 3 is a view of a detail of a sectional view of the collar portion of the mixing device.

(5) FIG. 4 is a schematic sectional view.

(6) FIG. 5 is an elevational side view of the plunger and of a mixing paddle with grip guided in the plunger.

(7) FIG. 6 is a perspective view of the plunger.

(8) FIG. 7 is a perspective view of a detail of the spring blades of the plunger.

(9) FIG. 8 shows a detail of the collar of the housing.

(10) FIG. 9 is a detailed view of the plunger latched in its cover position.

(11) FIG. 10 is a perspective detailed view of the mixing device with a funnel placed thereon from above.

(12) FIG. 11 shows an elevational side view of the mixing device with application tube screwed thereon.

DETAILED DESCRIPTION

(13) FIG. 1 shows an elevational side view of a mixing device 1.

(14) Mixing device 1 comprises a housing 2 which substantially has a circular cylindrical shape and serves to accommodate the material to be mixed.

(15) The housing has a bottom 5 which is detachable, in particular by being screwed off, for mounting an application tube. The latter may be attached by screwing for example after mixing of the bone cement.

(16) An underside of bottom 5 is planar thereby defining a footprint for the mixing device 1.

(17) The material to be mixed can be mixed by actuating a mixing paddle using grip 8.

(18) FIG. 2 is a sectional view of the mixing device 1 shown in FIG. 1. Here the circular cylindrical mixing cavity 6 can be seen.

(19) In the here illustrated position, a plunger 11 which serves to force out the mixed material is used as a cover prior to the mixing of the material to be mixed.

(20) A rod 10 for driving a mixing paddle 9 is guided in plunger 11. Rod 10 and hence mixing paddle 9 can be moved by means of grip 8.

(21) Mixing device 1 may be utilized as follows:

(22) After introducing the material to be mixed into mixing cavity 6, the plunger 11 together with the mixing paddle 9 guided on rod 10 is assembled. By moving the mixing paddle 9 using grip 8 the material to be mixed is mixed.

(23) Then grip 8 is retracted.

(24) The grip can be removed together with the rod.

(25) For this purpose, the rod has a predetermined breaking point 29.

(26) Mixing device 1 may then be inserted into an applicator gun (not shown), and after removal of bottom 5 the mixed material can then be forced out using a screw-connected application tube 4 by urging the plunger 11 forward using the applicator gun.

(27) FIG. 3 shows a sectional view of a detail of the collar portion of the mixing device.

(28) It can be seen that the collar 12 has an inclined surface 13.

(29) Plunger 11 has substantially L-shaped spring blades 15.

(30) In this figure, the cover position of plunger 11 is shown.

(31) In this position, a substantially horizontally extending support surface 14 of the plunger defines a stop for the spring blades 15.

(32) When an increased force is applied, the L-shaped spring blades 15 will resiliently deflect inwards and the plunger 11 can be moved forward.

(33) In a front portion 16 the diameter of the plunger increases.

(34) The front portion 16 is provided in form of a wiper attached on the rest of the plunger as a separate component, for example by snap-connection.

(35) Behind front portion 16, a seal is recessed in a groove of plunger 11, for example an O-ring of elastomeric material.

(36) In this way, the plunger is reliably guided in housing 2.

(37) Spring blades 15 are formed integrally with the adjacent plunger 11. Thus, no separate component is required in order to secure the plunger in the cover position illustrated here.

(38) FIG. 4 shows a schematic sectional view of the collar portion. Here again, the front portion 16 with enlarged diameter of the plunger 11 can be seen, as well as the seal 17 rearwards thereof. Before plunger 11 merges into the L-shaped spring blades 15, it has a circumferential groove 18.

(39) Spring blades 15 have a spring portion 20 and a hook portion 19 extending more horizontally than the spring portion.

(40) FIG. 5 is side elevational view of plunger 11 with the rod 10 with mixing paddle 9 and grip 8 guided therein.

(41) These components can be assembled once the material to be mixed has been introduced, optionally with the receiving cup (3 in FIG. 10), and plunger 11 serves as a cover.

(42) FIG. 6 shows a detailed view of plunger 11. Plunger 11 has a plurality of L-shaped spring blades 15. In the present exemplary embodiment, 16 spring blades are provided. Preferably, the plunger should have at least 6 spring blades.

(43) To be able to resiliently deflect inwards, the spring blades are separated from one another by cuts 30.

(44) The body of plunger 11 is in part defined by a lightweight structure 22 consisting of circumferential walls which are connected by webs.

(45) Moreover, plunger 11 has a circumferential groove 21 on its upper side which is used for inserting the receiving cup (3 in FIG. 10).

(46) Furthermore, a vacuum connection 23 can be seen on the upper side, by means of which the mixing device is connected to a vacuum pump during the mixing of bone cement in order to remove gases and avoid bubble formation.

(47) FIG. 7 shows a perspective detailed view of the spring blades of the plunger.

(48) It can be seen that the spring blades have a substantially vertical but slightly inclined spring portion 20 and a hook portion 19 that extends substantially horizontally.

(49) The lower surface of hook portion 19 defines an engagement surface 24 through which the plunger bears on a corresponding support surface of the collar (14 in FIG. 3) when in its cover position.

(50) The transitions of hook portion 19 and spring portion 20 are rounded to allow for better sliding of the L-shaped spring blades.

(51) FIG. 8 shows a detailed view of the collar portion of housing 2.

(52) It can be seen that the collar 12 has locking hooks 25. The upper surface of locking hooks 25 is an inclined surface 26 over which the spring blades slide upon insertion of the plunger.

(53) Then the spring blades will snap below the locking hooks 25, at least partially or in sections, and the plunger will be secured from being axially retracted. At the same time the front side of the spring blades will engage on support surface 14, so that the plunger is locked in its cover position.

(54) The inclined surface 13 can be seen, which facilitates resilient inward deflection of the spring blades when the plunger is advanced.

(55) Locking hooks 25 cover less of the circumference than the spring blades to allow insertion of the plunger with rather low force.

(56) This is particularly apparent in FIG. 9 which shows a perspective view of the latched plunger 11 serving as a cover. Sections of the spring blades 15 are latched under locking hooks 25.

(57) FIG. 10 shows a perspective detail view of the upper part of the mixing device with funnel 3 attached thereto.

(58) Funnel 3 is placed on the housing of the mixing device prior to the assembly of the plunger.

(59) Funnel 3 is divided into two areas, by a partition 27.

(60) The larger area 31 of funnel 3 is intended for introducing the powder component.

(61) The other area 28 is trough-shaped to facilitate filling of a monomer from an ampoule. This area 28 may comprise a sieve to reduce the risk of introducing glass fragments into the mixing cavity. Area 31 for filling the powder component, by contrast, is open above the housing of the mixing device.

(62) FIG. 11 shows the mixing device 1 before extrusion of the bone cement.

(63) The grip (8 in FIG. 1) was separated together with the rod (10 in FIG. 2) for actuating the mixing paddle. Furthermore, the bottom (5 in FIG. 1) was unscrewed and instead the application tube 4 was mounted on the housing 2. The thread provided for this purpose preferably has a high pitch so that less than one revolution is required for the mounting.

(64) Application tube 4 may have a predetermined breaking point 7 in order to be truncated, depending on the application.

(65) The mixing device illustrated herein is inserted into an applicator gun by means of which the mixed material is forced out.

(66) With the invention it was possible to simplify the handling and assembly and also the manufacturing of a mixing device for bone cement.

LIST OF REFERENCE NUMERALS

(67) 1 Mixing device 2 Housing 3 Funnel 4 Application tube 5 Bottom 6 Mixing cavity 7 Predetermined breaking point 8 Grip 9 Mixing paddle 10 Rod 11 Plunger 12 Collar 13 Inclined surface 14 Support surface 15 Spring blades 16 Front portion 17 Seal 18 Groove 19 Hook portion 20 Spring portion 21 Groove 22 Lightweight structure 23 Vacuum connection 24 Engagement surface 25 Locking hooks 26 Sliding surface 27 Partition 28 Trough-shaped area 29 Predetermined breaking point 30 Cut 31 Area for filling the powder component