MXPA05012892A - Device for mixing bone cement. - Google Patents

Abstract

Described is a device for mixing orthopedic bone cement, which comprises a syringe-type housing simultaneously forming an inner mixing chamber; an upper stopper having two apertures, an elongated central axis passing through one of said apertures and extending lengthwise the mixing chamber, a pipe where a vacuum chamber is connected being located at the remaining aperture; a lower stopper for obstructing a lower aperture whereby cement is released as a bone mixture and once the stopper is removed; an independent stem is introduced through the highest diameter upper aperture of the siring body or mixing chamber once the mixture is ready so as to be slid therein and the mixed bone cement discharged towards an injection cartridge; said central shaft includes a crank located at the upper portion thereof useful for rotating the same, the lower shaft portion being cut for allowing the components to be mixed, thereby obtaining a viscose uniform bone cement mixture.

Description

OSEO CEMENT MIXING DEVICE FIELD OF THE INVENTION.

The present invention relates to a device for the mixture of bone cement which has a viscous consistency, more specifically the Polymethylmethacrylate (PMMA) used to treat fractures or cavities in bones, such as those forming the vertebral body; once the mixture is made in said device, it is possible to fill disposable cartridges or 3 ml syringes since the cement is ready to be injected into the vertebral body.

BACKGROUND OF THE INVENTION.

In the prior art, devices are used that make the mixture of PMMA in free contact with the atmosphere, which causes problems, such as the heating of the cement at room temperature and its consequent loss of fluidity, which causes the syringe rod to injection collapses by the action of the pressure exerted. The filling of each one of the syringes considerably increases the time in the vertebroplasty process. Then a mixing and recharging device is necessary that avoids putting the PMMA in contact with the air, before being injected.

In the prior art there are mixing devices attached to the injection device, such as: U.S. Patent No. 5,190,191, issued March 2, 1993 to Reyman, describes a device for supplying a viscous fluid with a dual chamber, which uses a one-way valve between the supply chamber and the tank used to prevent backflow to the tank during the supply action of the PMMA; but this device is complicated in the operation.

U.S. Patent No. 5,252,301, issued October 12, 1993 to Nilson, which describes a bone cement delivery apparatus, which is mixed within the injection chamber, thereby resolving the problem of the transfer of cement and the escape of gases. A chamber with a rod is described to exert pressure and supply the bone cement within the vertebral body; but high delivery pressure is not achieved.

U.S. Patent No. 5,494,349, issued to Seddon on October 12, 1996, describes and protects a bone cement mixer in the form of a round vessel, with an axial axis, moved by a central crank connected to it. , said axis consists of an arrow with blades or side vanes that mix the cement components.

U.S. Patent No. 5,797,680, issued to Murria on August 25, 1998, describes and protects a manual device for mixing bone cement, connected to a vacuum pump that extracts the air bubbles generated in the shake. The manual mixer consists of a cylindrical body with an axial axis in whose upper end a crank is connected, which when rotated mixes the bone cement in the place and at the time where it is used, since in this way it is achieved that the cement has fluidity at the application site, just after it has been mixed.

The patent of the United States of America No. 5,842,785, granted to Brown and colleagues, on December 1, 1998, describes a device with a cylindrical chamber where the bone cement that is to be used in the filling of the bone body is mixed. It comprises a syringe-like cylindrical body that functions as a mixer; an endless axial shaft with an end handle and side vanes that rotate due to the manual impulse that is exerted through the round handle in an up and down movement. The axial axis is supported by a lid that, when discarded, leaves the mouth free where the syringe with which the bone cement is injected is connected.

The patent of the United States of America No. 6,033,105, granted the March 7, 2000 to Baker, describes a system that integrates a device to mix bone cement, however, emphasizes the supply device that uses an Auger screw mechanism that controls the supply pressure and eliminates the bubbles produced in the cement mixture.my.

The United States of America patent No. 6,395,006, granted the May 28, 2002 to Burchett, describes and protects a mixer and spout assembly with interchangeable components as required in the process of a vertebroplasty operation. In fact, it includes a container with a cylindrical shape where the bone cement is mixed, once the mixture is made, a device for supplying and supplying bone cement is connected.

BRIEF DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a device for obtaining a uniform mixture of bone cement carried out under sterile conditions, in this way a mixture with an appropriate consistency is obtained and in which the vacuum is made to avoid the bubbles that they may be trapped in the viscous substance.

It is another object of the present invention to provide a device for mixing bone cement whose body is in the form of a syringe with an upper lid and a lower lid; in said upper cover it has two holes, one for the mixer shaft and the other for connection to a vacuum chamber.

It is still another object of the present invention to provide a device for mixing bone cement having a manually operated rotating mixer, which extends inside the mixing chamber which is defined by the syringe-shaped body, said chamber Mixed is connected to a vacuum pump in order to reduce the internal pressure and remove the bubbles formed in the process of beating within the mass of bone cement.

It is still another object of the present invention to provide a device for mixing bone cement comprising a syringe-shaped body defining an internal mixing chamber, an upper lid that closes the mixing chamber and holds a manual mixing arrow which it has a handle at its upper end, also a tube associated with said cover which is connected by means of a hose to a vacuum pump; a lower cover to block the lower hole which prevents spillage of the cement in the mixing stage.

It is still another object of the present invention to provide a device for mixing bone cement in which once the uniform shaking of the dough is achieved, the upper lid is removed and a driving rod is introduced which forces the cement to exit through the lower duct of the mixing chamber, to which the lower plug has previously been removed. In this way, the bone cement injection cartridge is refilled.

BRIEF DESCRIPTION OF THE FIGURES.

Figure 1 is a cross-sectional view of the mixing device object of the present invention, with the syringe-shaped receptacle, the upper and lower plugs, the mixer and the tube connected to the vacuum pump being indicated.

Figure 2 is a cross-sectional view of the evacuation rod of the uniform mixture of bone cement.

Figure 3 is a cross-sectional view of the receptacle, the rod in the position of use to exert the evacuation action and a certain amount of bone cement already mixed.

Figure 4 is a perspective view of the location of the elements, in the position of use of the bone cement mixing device object of the present invention.

DETAILED DESCRIPTION OF THE INVENTION.

The invention relates to a cylindrical body device in the form of a syringe which in its internal part defines a mixing chamber where the components are beaten to obtain a uniform mass of bone cement, with the use of the present device consistency and fluidity, also air bubbles that could have formed in the process of beating are extracted from the bone cement. The central mixing shaft is moved through an upper external crank, said turning movement is carried out inside the housing or mixing chamber whose body is in the form of a syringe with its wide upper mouth and its lower exit orifice of reduced diameter; in said upper end a stopper is placed to seal and with a central through hole and another decentralized charged to one side, through the central hole passes the rotating mixing shaft and in the other a pipe or air outlet conduit is connected and gas produced in the mixing process; At the lower end of the mixing chamber is placed a rubber stopper that prevents the cement from spilling from the internal chamber in the mixing stage.

The bone cement is mixed in the operating room, the mixer is maintained under sterile conditions during mixing and is kept under low temperature conditions to prevent premature hardening, prior to injecting into the vertebral body or prosthesis where required. At the same time that the bone cement is mixed, the air inside the mixing chamber is removed. When the mixing process has been completed and a homogenous mass has been achieved, the top cover is removed and a rod is placed which, by applying pressure on it, is able to push the bone cement mixture to recharge an application cartridge with bone cement. of viscosity as low as possible to ensure fluidity.

The description will be more illustrative if Figure 1 is used as support, wherein the mixing device is described with all its component elements and comprises: a syringe-shaped mixing housing, which defines an internal mixing chamber; an upper plug (9) consisting of two cylindrical sections of different diameter with two holes that closes the upper end of said mixing chamber, the plug (9) holds an elongated arrow (11) extending axially along of the mixing chamber, said arrow is rotated manually by means of the crank (10 a) located at its broad upper end, the arrow body has a broken lower section (10) and parallel to the main axis of the arrow to assist the beat of the PMMA mass, a tube (7) housed in the other hole of the same top plug through which a hose is connected to a vacuum pump, said top plug consists of two cylindrical sections, one of smaller diameter that engages in the internal side wall of the mixing chamber, another larger diameter, which engages in the perimeter eyebrow defined at the upper end of the mixing housing; a lower plug (8 b) having an internal perimetric groove where it couples the tubular section of the elongated narrow body of the lower end of the housing and which occludes the hole defined by said narrow body located at the lower end of the mixing housing, this orifice defines the outlet gate of the mixed bone cement from the internal chamber of the body or housing in the form of a syringe.

Independently, the mixing device also consists of an elongated rod (12) and shown in FIG. 2, with an upper support member (17), the axially straight body rod (12) generally of cylindrical shape, a piston ( 16) and a rubber seal (15) located at the end of said axial body in continuation of the plunger (16). Said rod, when driven through the upper support member (17), urges the exit of the homogeneous mixture of the bone cement toward the lower hole defined by the narrow body of the housing.

When the plugs (9) and (8b) are located at the two upper and lower ends, respectively, and the chamber contains the substances to be mixed, which in most cases is a polymethylmethacrylate powder (PMMA) in combination with a liquid monomer methylmethacrylate (MMA), the vacuum pump is connected to the gas and air evacuation tube (7) and the central mixing shaft (11), which is driven by hand, is manually rotated. of the crank (10 a) to mix the components and obtain the bone cement in a suitable uniform consistency, the arrow (11) extends axially along the mixing chamber and up beyond the outer face of the upper stopper (9), consists of a straight axial section (11) of upper end, a broken intermediate section (10) and a straight lower end section that lie within and to the lower end of the mixing chamber; a straight section outside the mixing chamber and beyond the surface of the upper plug at the end of which a "Z" -shaped crank is placed to activate the rotation of the arrow and beat the bone cementsaid intermediate section of the arrow has a diagonally outward section, an enlarged straight section (10) and parallel to the main body of the central mixing arrow, a section diagonally inward and ending in a straight lower end section and in the same direction as the main body of the central mixing shaft (11) which extends axially along the mixing chamber. The intermediate section (10) is manually rotated by means of the crank (10 a), in the action of rotation mixes the bone cement components to achieve a homogeneous mass and free of bubbles. Then to dispose of the cement or load an injection cartridge, the following steps are followed: the plugs are removed, first the upper one together with its associated components such as tube and shaft, body of the independent rod (12) is introduced, so that in act The lower plug (8 b) is then removed to allow the flow of bone cement through the lower exit orifice of the main mixing body. All these steps are carried out in conditions of sterility and as quickly as possible, that is, in less than a minute because otherwise the cement loses its properties and hardens violently, losing fluidity. The gas and air evacuation tube (7) is connected to a vacuum pump which extracts the air bubbles formed in the whipping operation, said tube extends from the lower face of the upper plug (9) and up to beyond the upper face of said stopper, at its upper end has a right angle fold that gives it an inverted "L" shape in the use position, said end is connected to a flexible hose that communicates the mixing device of the present invention with a vacuum pump which is not shown.

The rod (12) of figure 2, is introduced hermetically into the internal mixing chamber to push out the homogenous mass of bone cement achieved by the manual mixing process, the coupling of the rod into the mixing chamber it is airtight since the plunger (16) and the rubber seal (15) do not allow the bone cement mass to escape upwards through the side walls of the mixing chamber, only the mixing of the mixture is permitted means of the lower hole of the syringe body defining the internal housing for preparing the mixture. In the ejection of the bone cement, a force is exerted on the upper support (17) of the rod, with the fingers resting on the outer wall of the perimeter eyebrow of the upper end of the syringe body that defines the housing to perform the mixing, with this action, the displacement of the plunger is achieved inside the chamber and the expulsion of the mixed homogenous mass is achieved, through the orifice (8 b).

In Figure 3, the rod (12) is shown inside the housing (8) which defines the internal mixing chamber in the evacuation position and further pushes the bone cement out through the hole defined by the lower narrow body (8 c). ) of the syringe body. The body of the housing in the form of a syringe (8) defining the internal mixing chamber, has a perimeter upper support boundary (8 a) of greater diameter than the mixing chamber in whose inner edge the larger diameter section of the upper plug (9) used in the mixing stage, to isolate the mixture from the environment, this upper hole is free once the plug has been removed to introduce the rod, the eviction is carried out due to the pressure exerted by the rod in cooperation with the plunger (16) and the rubber seal (15) that force the cement to flow through the orifice defined by the elongated narrow lower body (8 c).

Figure 4 represents the bone cement mixing device, object of the present invention, in a perspective view where the operating position of each of the components is located, namely, the body is shown in the foreground of syringe defining a housing (8) for mixing bone cement; the lower plug (8 b) coupled in the hole defined by the lower narrow body (8 c); the perimeter eyebrow (8 a) at the upper end of the housing (8) and with a larger diameter than the mixing chamber; the crank (10 a) in the form of "z" coupled to the upper end of the central mixing arrow (11); the inverted "L" shaped tube (7) where the vacuum pump is connected that extracts the gases produced in the mixture and the air trapped in the mixing process; with dotted lines, the location of the upper plug (9) and its through holes (9 a), (9 b), the central mixing arrow (11), through which the central mixing arrow (11) are passed respectively (11) is shown. ), the tube (7) and are brought into contact with the interior of the chamber and the substances to be mixed, it is noted the broken line shape (10) of the lower end part of the central mixing arrow (11) which forms a mixing arm with two diagonal sections and a section parallel to the axis of the mixer. In the mixing step, the crank (10 a) can be rotated in both directions, left and right, to prepare the mixture of the bone cement; thus also the mixing device can be placed vertical, inclined, horizontal, upwards, etc., since it is small in size and totally manual and manageable, holding it with one hand and operating the handle with the other; also the totally portable and can be easily transported once the bone cement mixture has been made.

Claims (6)

1. Bone cement mixing device, comprising: a housing in the form of a syringe defining an internal bone cement mixing chamber, said housing having a wide open upper end and a narrow open lower end; a rubber upper plug with two through holes and adapted to engage in the open upper end of the housing; a central mixing arrow with a broken intermediate section, said arrow passing through the hole in the center of the cap and extending axially along the mixing chamber; a gas and air evacuation tube that passes through the off-center hole in the plug, which is connected to a vacuum pump; a rubber lower plug adapted with a perimetric groove for coupling at the open lower end of the housing.

2. - The bone cement mixing device according to claim 1, further characterized in that the syringe-shaped housing has a broad, open upper end defined by a perimeter eyebrow of larger diameter than the mixing chamber, and a narrow open end defined by an elongate body at the lower end of the housing.

3. - The bone cement mixing device according to claim 1, further characterized in that the upper plug consists of two cylindrical sections, one of smaller diameter that engages in the internal side wall of the mixing chamber, another larger diameter that couples in the perimetric eyebrow of the upper end of the housing, a through hole in the center through which the central mixing arrow passes, an off-center hole through which the connecting tube passes to the vacuum pump.

4. - The bone cement mixing device according to claim 1, further characterized in that the lower plug comprises an internal perimetric groove, where the tubular section of the elongated narrow body of the lower end of the housing engages and which occludes the hole defined by said narrow body.

5. - The bone cement mixing device according to claim 1, further characterized in that the central mixing shaft extends axially along the mixing chamber and out of the upper plug, it consists of an axial upper end section straight, a broken intermediate section and a straight lower end section that are located inside the mixing chamber; a straight upper section outside the mixing chamber and beyond the surface of the upper plug, at the end of which is placed a "Z" -shaped crank to manually actuate the rotation of said arrow.

6. - The bone cement mixing device according to claim 1, further characterized in that the gas and air evacuation tube is connected to the vacuum pump and extends to the edge of the lower face of the upper stopper, and also up beyond the upper face of said stopper; at the upper end said tube has a right angle bend that gives it an inverted "L" shape.