Bone cement applicator with clampable delivery plunger

Patent metadata

Field	Value
Publication number	US-11701156-B2
Application number	US-202016793150-A
Country	US
Kind code	B2
Filing date	Feb 18, 2020
Priority date	Feb 18, 2019
Publication date	Jul 18, 2023
Grant date	Jul 18, 2023

Abstract

One aspect relates to a bone cement applicator having a cartridge with an interior, a cartridge head with a delivery opening, a mixing member which is movable in the interior with a mixing rod. A delivery plunger is arranged in the cartridge and is mounted in the interior and is pressable in the direction of the delivery opening. The delivery plunger rests with an outer cylindrical circumferential surface against an inner wall of the cartridge. A clamping element is arranged on the inner wall of the cartridge in the region of a back side of the interior. The clamping element projects out of the inner wall of the cartridge. The cylindrical circumferential surface of the delivery plunger is resiliently deformable by the clamping element in the direction of a central cylinder axis, such that the delivery plunger is clampable in place with the at least one clamping element on the back side of the cartridge.

First claim

The invention claimed is:

1. A bone cement applicator for providing a polymethyl methacrylate bone cement, the bone cement applicator comprising:
a cartridge with a cylindrical interior;
a cartridge head with a delivery opening for discharging the bone cement, wherein the cartridge head closes the cylindrical interior of the cartridge at a front side of the cartridge except for the delivery opening;
a mixing member movably arranged in the cylindrical interior of the cartridge and is movable in the interior with a mixing rod guided into the interior;
a delivery plunger arranged in the cartridge and is mounted slidably in the direction of the delivery opening in the cylindrical interior of the cartridge, wherein the delivery plunger has an outer cylindrical circumferential surface and wherein the delivery plunger rests with its outer cylindrical circumferential surface against an inner wall of the cartridge, the inner wall defining the cylindrical interior; and
at least one clamping element arranged in the region of a back side, opposite the front side of the cartridge, of the cylindrical interior on the inner wall of the cartridge, the inner wall defining the cylindrical interior, wherein the at least one clamping element projects out from the inner wall of the cartridge in the direction of the cylindrical interior;
wherein the cylindrical circumferential surface of the delivery plunger is at least in places resiliently deformed by the at least one clamping element in the direction of a central cylinder axis of the cylindrical interior, such that the delivery plunger is clampable in place with the at least one clamping element on the back side of the cartridge.

2. The bone cement applicator according to claim 1 , wherein the at least one clamping element is formed as a part of the cartridge.

3. The bone cement applicator according to claim 1 , wherein the delivery opening is closed or closable in the cartridge head with a releasable closure, wherein a thread is arranged on the cartridge head, into or onto which the closure is screwed or screwable with a mating thread which fits the thread, in order to close the delivery opening.

4. The bone cement applicator according to claim 1 , wherein an external diameter of the delivery plunger is the same size as or smaller than the internal diameter of the cylindrical interior of the cartridge, wherein at least one circumferential seal and/or a circumferential wiper lip is arranged on the outer circumference of the delivery plunger.

5. The bone cement applicator according to claim 1 , wherein the internal diameter of the cylindrical interior of the cartridge is reduced in the region of the at least one clamping element by the at least one clamping element, wherein the internal diameter is reduced to such an extent that the delivery plunger has an external diameter larger than the internal diameter reduced by the at least one clamping element.

6. The bone cement applicator according to claim 1 , wherein the at least one clamping element is a circumferential, closed projecting rail or portions of a circumferential rail or at least two circumferential, closed rails spaced apart in an axial direction or at least two portions of a circumferential rail spaced apart in an axial direction.

7. The bone cement applicator according to claim 1 , wherein the at least one clamping element has a chamfer on a front side of the at least one clamping element, said front side facing towards the front side of the cartridge, and a chamfer on a back side of the at least one clamping element, said back side facing towards the back side of the cartridge.

8. The bone cement applicator according to claim 1 , wherein two or more clamping elements are arranged, axially spaced apart with regard to the longitudinal cylinder axis, on the inner wall defining the cylindrical interior.

9. The bone cement applicator according to claim 1 , wherein an outer wall of the delivery plunger, the outer wall facing towards the inner wall of the cylindrical interior, has an axial extent which is at least the same size as the axial extent of the at least one clamping element, wherein the axial extent of the outer wall of the delivery plunger is at least twice the size of the axial extent of the at least one clamping element.

10. The bone cement applicator according to claim 1 , wherein an outer wall of the delivery plunger, said outer wall facing towards the inner wall of the cylindrical interior, is formed as a hollow cylinder.

11. The bone cement applicator according to claim 1 , wherein the delivery plunger clamped in place by the at least one clamping element is releasable by the action of a force directed along the cylinder axis of the cartridge and is pressable in the direction of the front side of the cartridge.

12. The bone cement applicator according to claim 1 , wherein the outer cylindrical circumferential surface of the delivery plunger consists of a thermoplastic, wherein the thermoplastic is selected from at least one of the plastics materials polyethylene, polypropylene, polyamide, polyethylene terephthalate and polybutylene terephthalate.

13. The bone cement applicator according to claim 1 , wherein the bone cement applicator has a sealing plunger which is connectable to the delivery plunger, wherein the delivery plunger comprises the outer cylindrical circumferential surface and a passage which is permeable to gases but impermeable to the cement powder and wherein the passage in the delivery plunger is closable by the sealing plunger.

14. The bone cement applicator according to claim 13 , wherein the passage in the delivery plunger is closable by the sealing plunger by inserting the sealing plunger into an opening of the delivery plunger, the opening being open in the direction of the back side of the cartridge, wherein the passage is arranged within the opening of the delivery plunger.

15. A method for producing a paste-like polymethyl methacrylate bone cement, wherein the bone cement paste is produced from a cement powder and a monomer liquid using a bone cement applicator according to claim 1 , characterized by the following succession of steps:
A) introducing the cement powder and the monomer liquid into the cylindrical interior of the cartridge or the monomer liquid to the cement powder in the cylindrical interior of the cartridge,
B) closing the back side of the cartridge by pressing the delivery plunger into the cylindrical interior of the cartridge,
C) clamping the delivery plunger in a fixed place on the back side of the cartridge with the at least one clamping element,
D) mixing the bone cement in the cylindrical interior of the cartridge by moving the mixing member in the cylindrical interior of the cartridge,
E) pressing in the delivery plunger in the direction of the front side of the cartridge, wherein the clamping effect of the at least one clamping element is released, and
F) expelling the bone cement from the cartridge through the delivery opening by advancing the delivery plunger in the interior of the cartridge in the direction of the cartridge head.

16. The method according to claim 15 , wherein the cement powder is introduced into the interior of the cartridge before the monomer liquid or is already present in the cylindrical interior of the cartridge.

17. The method according to claim 15 , wherein on clamping the delivery plunger in place in step C), the delivery plunger is resiliently deformed in the direction of the cylinder axis of the cylindrical interior of the cartridge, wherein a tubular extension on the back side of the delivery plunger, t

Assignees

• Heraeus Medical Gmbh

Inventors

• Vogt Sebastian
• Kluge Thomas

Classifications

• A61B17/8822 Primary

  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 title

• A61L24/06

  obtained by reactions only involving carbon-to-carbon unsaturated bonds {(A61L24/043, A61L24/046 take precedence)} · CPC title

• B01F23/511

  characterised by the composition of the liquids or solids · CPC title

• B01F35/754251

  reciprocating in the mixing receptacle · CPC title

• A61B2017/00955

  thermoplastic · CPC title