The present invention is generally concerned with the preparation of orthopaedic cement which has many applications. Specifically, the invention is concerned with orthopaedic cements of which one component is a liquid monomer such as a methyl methacrylate monomer which is mixed with, for example, a liquid polymer to form the cement. Specifically, the invention is concerned with providing a device for delivery of the monomer to the other cement component(s) for mixing. One common approach to forming orthopaedic cement or bone cement is to mix a monomer liquid such as methyl methacrylate or other acrylate monomer with a bone cement powder component such as polymethyl methacrylate. Many other bone cement products and components are known in the field, including

combinations of methyl methacrylate, N,N-dimethyl-p-toluidine, hydroquinone, chlorophyll-copper complex, peanut oil, as a liquid component and polymethyl methacrylate, methacrylate/styrene copolymer, benzoyl peroxide, barium sulfate, zirconium dioxide as a powder component. Commonly used bone cement products are known as "Endurance" from DePuy Orthopaedics, Inc., "Palacos" R by

Schering-Plough, Inc. and "Simplex P" by Stryker Howmedica Osteonics and "Palamed". Each of these cement preparations consists of a liquid component in a glass ampoule and a powder component. The three products mentioned above use MMA monomer, primarily, as the liquid component and polymethyl methacrylate or a related copolymer as the powder component. To form the orthopaedic cement, these two components need to be thoroughly mixed together and several mixing devices have been developed and are in use for providing such thorough mixing. Preferred devices provide mixing in a vacuum to avoid air bubbles being created in the cement mixture and the devices are often adapted to prevent the escape of fumes, particularly from the MMA monomer, into the operating room. Some existing mixing devices are in the form of a combined mixer and dispensing device such as a mixing syringe wherein the cement can be mixed within the body of the syringe and dispensed through a nozzle at the end of the syringe. Other mixing devices are in the form of a bowl mixer in which, for example, the components are inserted in the bowl and a paddle is rotated to mix the components. Although it is possible and known to mix the components in an open bowl and, indeed, some surgeons actually prefer this as they can then test the consistency of the mixed cement using their hand, most commercial mixers now comprise a lid to which the mixing paddle or agitator is attached. Some commonly used mixing devices are bowl mixers such as supplied by Stryker Howmedica, Summit Medical Ltd., and DePuy Orthopaedics or syringe mixers again as manufactured by e.g. Summit Medical Ltd. and DePuy Orthopaedics.

As mentioned above, the monomer liquid is usually provided in the form of a glass ampoule and this needs to be kept sealed and separate from the powder until the time of mixing, since, once the liquid and powder components come into contact the mixture begins to set. Consideration has to be given, therefore, as to the best way of introducing the monomer into the mixture at the appropriate time. In particular consideration has to be given to avoiding or at least minimising the release of monomer gas or fumes into the environment and, also, to avoiding glass from the monomer ampoule getting into the cement mixture or into the mechanism of the mixer when the ampoule is broken to release the liquid.

Although liquid monomers such as MMA are generally considered to result in the best orthopaedic cement, there are concerns about the fumes released by such monomers. The use of MMA in particular has been seen as a potential exposure hazard to health care professionals as discussed in some detail in "Control of Methyl Methacrylate During the Preparation of Orthopaedic Bone Cements" by Leslie J. Lingers et al.; Journal of Occupational and Environmental Hygiene, April 2007 pp. 272-280.

Investigation by the present applicants, resulting in customer feedback, has highlighted the fact that fume reduction in operating theatres, etc. during the preparing of bone cement is the main issue of concern to end users in the UK ₁ European and US markets. In the US, in particular, restrictions in US operating room practice limits pregnant nurses from attending operations where MMA is used, due to the emitted vapours or fumes from the MMA. This clearly affects both the nurse or technician, who is restricted in their work, and the surgeon who loses a key member of the team. Further, as mentioned above, ampoules are often difficult to break neatly and this can cause glass shards to enter the cement mixture or the mixing mechanism or to cause cuts to nursing staff or operating room personnel. Furthermore, spillage of the monomer can cause inferior cement quality if the total supply is not used, since the final form of the cement depends upon precise dosages of cement components.

Various techniques, systems and devices are known for introducing liquid monomer into a cement mixture and many attempt to solve some or even all of the problems mentioned above.

In some devices, the mixing device itself actually houses a glass monomer ampoule. Such devices are known as fully pre-filled mixing systems since they are provided with the glass ampoule containing the monomer and also with the polymer powder, together in the mixing device. In use, the ampoule is broken by means of a metal pin or spike, at the end of the ampoule, within the mixer itself. Such systems have, however, had limited success, primarily due to a poor mixing action and also due to the fact that the user is limited to the type or cement provided in the pre-filled mixer and the inability to use the mixer with other cements, particularly new cements coming onto the market.

Other known solutions provide a partially pre-filled system in which the polymer powder is provided in the mixing device and the device is sold together with a separate monomer introducer, pre-loaded with ampoules. The ampoules are then broken within the monomer introducer and introduced, through a port, into the mixer containing the cement powder. DePuy Orthopaedics, Inc. currently market a range of mixing device such as a syringe mixer and a bowl mixer, each supplied with a separate monomer introducer adapted to be mounted to and sealed to the ampoule port of the specific mixing device.

One of the DePuy monomer introducers breaks the glass monomer vials for ampoules by applying pressure to the top of the vial with a metal pin spike on the underneath of the introducer that breaks the vial at the end. Another monomer introducer of DePuy, as shown, for example, in US 2002/0003146, breaks the necks of the vial using a twisting action.

In the known devices where the monomer ampoule or vial is broken by a pin that penetrates the bottom of the vial, these are, clearly, limited to ampoules of a particular length but, since these known devices are provided pre-filled, the manufacture is already in a position to control the length of the ampoule. Such devices would not, however, be able to simply be used, effectively, for different lengths of ampoule, allowing the clinician to select the appropriate cement components. Commonly used ampoules vary in length by around 10 mm.

Furthermore, with the arrangement described above in which the neck of the ampoule is broken, it was found to be often the case that some monomer was left behind within the inverted, broken-off neck section.

Thus, an alternative solution to the problems mentioned above is required, and preferably a solution which provides a monomer introducer that can be used with a variety of mixing devices and provided empty - i.e. not pre-filled so that the clinician using the cement has some freedom of choice as to the cement components he wishes to use, without requiring a different monomer introducer for each type of monomer ampoule.

The present invention, therefore, provides a device for breaking an ampoule containing liquid monomer wherein the device is arranged to receive an ampoule and wherein the device comprises means for penetrating or fracturing the ampoule along a long side of the ampoule. Preferably, the device has a top and a bottom and a longitudinal axis extending between the top and the bottom with means for receiving the ampoule such that the longitudinal extent of the ampoule corresponds essentially to the longitudinal axis of the device, and wherein the device comprises means for penetrating or fracturing the ampoule, when received within the device, and means for moving this means for penetrating or fracturing in a direction toward the longitudinal axis.

The means for penetrating or fracturing the ampoule is preferably one or more spikes or protrusions. Whilst these could, in theory, be moved in towards the ampoule stored in a device in many ways, in the preferred embodiment, one or more such spikes or protrusions are mounted on a lever forming a side of the device between the top and bottom, the lever being movable in towards the longitudinal axis, in use, such that the spike(s) contacts and penetrates an ampoule received between the top and bottom of the device as the lever is closed against the device.

When closed, the lever preferably forms a seal against the device to provide a complete sealed housing around the ampoule.

In an alternative embodiment, the spike(s) or protrusion(s) are mounted on a rotatable handle, rotation of which causes the spike(s)/protrusion(s) to move in relative to the ampoule(s) in the device. The handle is preferably mounted to the device body by a screw thread.

Thus, in the present invention, an ampoule inserted within the device is broken from the side - i.e. by movement of the spike(s) towards the longitudinal axis, as opposed to being penetrated at the top or bottom - i.e. by movement of the spike along the longitudinal axis.

The introducer device is preferably provided with an outlet port, preferably at the bottom of the device, arranged to be located and sealed onto a port of a mixing device such that the liquid monomer from the broken ampoule enters the mixing device through the outlet port of the introducer.

In order to avoid fragments of glass entering the cement mix, a filter is preferably provided in the introducer, most preferably in the outlet port, but at least somewhere in the path between the breaking of the ampoule and the liquid entering the cement mixer.

Preferred embodiments of the monomer introducer of the present invention will now be described in more detail with reference to the drawings. Fig. 1 shows an introducer of one embodiment, in a closed position, for example as supplied by the manufacturer;

Fig. 2 shows the monomer introducer of Fig. 1 in an open position for insertion of a monomer ampoule;

Fig. 3 shows the insertion of a monomer ampoule into the introducer of Figs. 1 and 2; Fig. 4 shows the introducer closed, containing the ampoule, the position in which the ampoule will be broken;

Fig. 5 shows a more detailed view of the bottom of the introducer, in an open position, showing the position of the spike for breaking the ampoule; and

Fig. 6 shows a more detailed view of the same part of the introducer as Fig. 5, but with the lever closed.

Fig. 7 shows an alternative embodiment introducer mounted to the lid of a mixer;

Fig. 8 is a perspective view of the introducer of Fig. 7 containing two ampoules;

Fig. 9 is a detailed view showing the ampoule breaking part of the introducer of Fig. 7;

Fig. 10 shows more detailed views of the handle and lid of the embodiment of Fig. 7;

Fig. 11 is a detailed view, in part section, showing how the introducer of Fig. 7 attaches to a mixer;

Figs. 12 to 15 are detailed sectional views of the ampoule breaking mechanism of Fig. 9. Figs. 16 and 17 show an alternative embodiment. In one embodiment, the monomer introducer functions a little like a nutcracker, to break the ampoule.

The introducer of one embodiment, shown in Figs. 1 to 6, comprises a main body or sleeve 1 adapted to receive a monomer ampoule 2. Preferably, this body is of such a size and configuration that ampoules of various known shapes and sizes can be contained therein. In the embodiment shown, the main body is in the form of a cylindrical sleeve, open at the top to receive the ampoule. A port 3 is provided at the bottom for dispensing the monomer from the opened ampoule into a cement mixer and a filter 4 is provided in the outlet port. The use of a filter is not essential or, indeed, the filter could be provided elsewhere, even in the mixer, to which the introducer is attached. However, the embodiment shown herein is preferred as this prevents glass from the broken ampoule leaving the introducer. Towards the bottom of one side of the sleeve or main body is provided a hole 5 through which a spike 6 provided on the lever 7, discussed below, will protrude, when the lever is closed, to break the ampoule inserted in the main body. As will be mentioned again below, the lever may be provided with more than one spike or protrusion and a corresponding number of holes may then be provided along the body of the sleeve. All that is essential is that the spike or spikes are able to be brought into contact with the ampoule contained within the main body. It may be, therefore, that the main body is completely open along one side and sealed by the lever or some other means on which the spike or spikes is/are mounted. The introducer is generally supplied in the closed position as shown in Fig. 1.

Provided as part of the introducer is a lever or panel 7 on which one or more spikes 6 are mounted. Of course, this lever is not essential to the invention and it would even be possible to have a stand-alone spike for insertion into the main body or a spike provided on some other means for advancing the spike.

In the embodiment shown, the lever is attached to the bottom of the sleeve by a hinge 8.

At the top of the lever, a lid 9 is provided - hinged to the lever which, when the lever is closed, fits over the top of the main body. The lid and/or the sleeve may be provided with some sort of a catch or locking arrangement to lock the lid to the main body in the closed position. Of course, a separate lid may be provided and this does not need to be integrally formed with the lever. As shown in Fig. 2, to use the introducer, the lid 9 is lifted or removed and the lever 7 is pushed away from the main body 1 , thus withdrawing the spike 6 at the hole 5 in the main body. As mentioned above, the use of a lever is not essential but, before the ampoule 2 is inserted, the spike will need to be removed so that it does not extend into the receptacle into which the ampoule is placed, until such time that the user wishes to break the ampoule.

As shown in Fig. 3, one or more ampoules of a size and type desired by the clinician are dropped into the main body of the introducer. The lever 7 is then pushed forward towards the main body 1 to close the lid 9 and this action causes the spike 6 to extend through the hole 5 in the main body and penetrate the ampoule(s) 2. Where a lever is not used, other appropriate action will be taken to penetrate the ampoule contained in the main body by the spike(s).

In a preferred arrangement shown, when the lever is in the closed position, the spike 6 will seal the hole in the side of the main body. In an alternative

arrangement, a skirt (not shown) could be provided around the spike to form a seal. A sealing arrangement is preferable to avoid the escape of fumes from the monomer exiting from the broken ampoule. Of course, more than one spike or protrusion can be provided but at least one spike should be provided close to the bottom of the receptacle for receiving the ampoule(s). The fact that the spike penetrates the ampoule towards the bottom but from the side means that the ampoule will be broken independent of its height and, therefore, any standard ampoules can be inserted into the introducer and broken.

In order to keep the lever open until the ampoule is desired to be broken, some sort of detent feature (not shown) can be provided such as a spring arm that biases the lever away from the main body until force is applied to push the lever into the body. A latch may be provided on the lever, for example at or near the lid 9, to lock the lever in a closed position after the ampoules have been broken, to avoid escape of vapour. Whilst the introducer of the present invention can be used to receive a single glass ampoule of monomer, it is often necessary, depending on the application, for the clinician to use two or more ampoules to obtain the desired amount of cement or the desired mix. Whilst the introducer of the present invention could be used to break a single monomer at a time until the clinician has the desired amount of monomer, it can be advantageous for the introducer to be designed to receive two or more ampoules at the same time and, in a more preferred embodiment, to break both ampoules at the same time.

The drawings show an introducer arranged to receive two ampoules and, in preferred embodiments, two spikes are provided on the lever to break the respective ampoules.

In testing this arrangement, however, it was found that the design does not always result in both ampoules being broken when force is applied to the spikes. Solutions have been found to this problem which also fall within the present invention.

The problem may be solved by, for example, increasing the length of the spike(s) and/or increasing the rigidity of the component parts. A further possible solution is to have the spike(s) sealed and mounted on a side of the main body, so the unit is sealed and for pressure to then be applied from the side to push the spikes to break the ampoules. The spikes could be pushed, for example, by force applied from a lever such as shown in the drawings or some other means could be used to move the spikes mounted on the main body, such as a clamp arrangement.

An alternative arrangement may be to provide spikes at different positions corresponding to the locations of the ampoules within the main body, for example providing spikes on separate levers or other means for moving the spikes from different locations e.g. from different sides of the main body. An alternative arrangement would be to retain the design shown in the drawings - i.e. having the spikes arranged on a single lever or some other means for moving the spikes in towards the ampoules but then to further permit a secondary movement by the user if both ampoules do not break - i.e. to allow some flexibility within the main body to enable the user to squeeze the container to add further pressure to the spikes and/or glass until the ampoules break. All of these embodiments are within the scope of the present invention. Similar arrangements could be modified to receive three or more ampoules, using the same principles.

An alternative embodiment introducer is shown in Figs. 7 to 15. The principle of, and advantages of breaking the ampoule(s) from the side is the same as for the embodiments described above, but the structure is different.

In this alternative embodiment, the spike(s) for penetrating the ampoule(s) are provided on a rotatable or screw handle that is attached to the main body. As can be seen from, e.g., Fig. 7, the main body 1' is similar to that of the previous embodiments except that, rather than the spikes being provided on a lever that is moved by a hinged movement in towards the ampoules to break the ampoules, a spike or spikes are provided on a handle 10 which is arranged to be mounted on or is integrally formed with the main body. In the preferred embodiment shown, the handle is attached to the main body 1' by a screw thread 11 and one or more spikes are preformed or pre-mounted onto the handle.

Fig. 9, for example, shows a screw thread, provided on the main body 1', to which the rotatable handle can be mounted. The more detailed portion of Fig. 9 shows two spikes 6' that would be provided with the handle.

Fig. 10 shows a back view and a perspective view of a preferred form of handle provided in a shape that is easy to grip and rotate with a single hand. Of course, any other form of handle can be used that enables the preferably pre-assembled spike(s) to be moved in towards the ampoule(s) relative to the main body. The bottom of Fig. 10 shows one embodiment of a lid 9' that is similar to the lid provided in previous embodiments. With reference to Figs 7 to 15, again, and in particular Figs. 11 to 15, the use of the second embodiment will now be described.

The introducer may be supplied with two pre-mounted ampoules 2' as shown in Fig. 8. Alternatively, the introducer can be provided empty and the user can insert preferred ampoules. Other embodiments are also possible having only a single ampoule or having more than two ampoules.

Before use, the handle is mounted relative to the main body and the ampoules such that the spike or spikes 6 ¹ extend into the main body but do not actually extend as far as the ampoule. This can best be seen in Figs. 11 to 15. In Fig. 11, only one spike is shown and this is in such a position that it is not yet penetrating the ampoule surface.

The introducer is then fitted to a mixing device via its dispensing port 4' in a manner similar to that previously described.

When the cement is ready to be mixed, the user actuates the handle so as to advance the spike(s) relative to the side wall of the ampoule(s). Fig. 11 shows only one spike in a position before this has penetrated the ampoule wall. In this embodiment, the spike is advanced by rotating the handle relative to the main body. The handle is mounted to the main body by means of a thread and as the handle is rotated it moves towards the main body, along the thread, thus advancing the spike(s).

In other embodiments, the handle could be activated by pushing relative to the main body or by some sliding or other movement so as to advance the spike into the ampoule(s). As with the other embodiments described, if only a single ampoule is provided, this can be penetrated by a single spike.

In the embodiment shown, two ampoules are provided, each being penetrated by a respective spike - i.e. the handle is provided with two spikes.

Whilst, in some embodiments, the spikes could be mounted both at the same distance from the ampoules such that both spikes penetrate the respective ampoules at the same time, in other embodiments, such as shown in Figs. 12 and 14, in particular, the spikes may be offset such that a first spike penetrates a first ampoule, first, and then further actuation, e.g. rotation of the handle, causes further advancement of the second spike which penetrates the second ampoule later.

Of course, in other embodiments, where more than two ampoules are provided, more than two spikes may be provided but the same principles apply.

Thus, as can be seen in Fig. 12, in this embodiment, a first rotation of the handle causes the first spike to penetrate the first ampoule but the second spike has not yet reached the ampoule wall of the second ampoule.

Further rotation of the handle causes the second spike to penetrate the wall of the second ampoule, again from the side.

This particular embodiment is very simple to use and, being a complete field unit, avoids the escape of fuse into the environment. The knob is preferably designed such that the introducer can be operated with a single hand.

The handle is preferably snap-fitted into the thread of the main body so that it cannot be taken off.

One problem that has arisen with the embodiment described above is that the amount of force required to compress the spike(s) 6' tended to cause the sleeve 1 and the handle 10 to distort or pull apart. One possible solution to this is shown in Figs. 16 and 17. Here, a pin 20 passes through the sleeve 1 and connects to the handle 10 via a thread. When the handle is rotated to compress, the entire assembly is pulled together and the spike(s) can load uniformly.

The monomer introducer of the present invention can be provided partly pre-filled - i.e. pre-filled with monomer ampoules but a particular advantage of the present invention is that this is not necessary and that any standard ampoules can be used with the monomer introducer. Thus, the introducer of the present application can be supplied as an empty device, not dependent on the type of cement used. The device of the present invention, particularly in its preferred embodiments, contains all monomer fumes and also filters any glass from the fractured ampoule. The device can be provided as a stand-alone device or may be provided in a kit with or as part of a mixing device. In use, the monomer introducer is located and sealed onto a mixing system. The ampoules will then be broken within the introducer and the monomer liquid will pass through the outlet port into the mixer to be mixed with the cement powder.

The introducer of the present invention is particularly cost effective and allows the clinician to use any bone cement with this introducer. Compared to current mixing systems, it has been found that the fumes emitted are greatly reduced or removed. The introducer is particularly easy to use and ensures that any broken glass is filtered to avoid glass entering into the cement mix or the mixer mechanism or injuring medical personnel.

The use of the introducer of the present invention avoids the need to break ampoules by snapping by hand and avoids the need to break ampoules within the mixer device itself. Used ampoules can be safely disposed of.