The invention herein relates to the field of medical devices. In particular, the invention pertains to a system for preparing surgical cement compositions for medical applications.
Certain medical procedures require the preparation of curable polymer compositions in advance of their application or delivery to the patient. For example, certain medical procedures such as orthopedic repair or reconstruction sometimes require the use of orthopedic bone cement which can be delivered in fluid or shapeable form and which subsequently cures and hardens in the target location. One commonly used bone cement is polymethylmethacrylate, also known as PMMA or methacrylate cement. Bone cement such as polymethylmethacrylate is prepared by mixing the ingredients immediately prior to its delivery to the patient, and has a relatively short upper time constraint before it begins to hardens. Accordingly, the ability to mix the ingredients together thoroughly and deliver the composition quickly and accurately are critical to the success and desired results of the associated surgical procedure.
Bone cements such as polymethylmethacrylate typically involve the admixture of a liquid component together with a powder component. Furthermore, if additional properties are desired from the cement, such as radiopacity, additional ingredients, such as barium sulfate powders, may also be added and combined with the cement components per se. The mixing equipment, therefore, must permit the rapid and accurate addition and combining of multiple ingredients in multiple physical form, i.e., liquid and solid. Such equipment should also ensure proper proportioning of the ingredients as well.
One mixing system is available from Parallax Medical, Inc. (Scotts Valley, Calif.) under the trade name Tracer™. The Parallax product provides an opacifier within a capped plastic vial. Another mixing system is available from Bryan Corporation (Woburn, Mass.) under the name of Biotrace™. The Bryan Corporation product provides an opacifier within a glass container, from which then opacifier is poured. Such systems are absent additional components and/or significant features which can facilitate rapid and clean combining of ingredients by themselves.
There is a need in the medical field, therefore, for surgical cement mixing and preparation systems which facilitates clean, accurate, safe and rapid mixture and transfer of the resulting composition.
The invention provides a surgical cement preparation system designed for the rapid, clean, safe, accurate and thorough handling and combining of cement ingredients—namely a liquid ingredient together with one or more dry-state powder ingredients. It has been discovered that components of a mixing system can be structured to interact cooperatively with other components to facilitate rapid and thorough combining of the cement ingredients while at the same time reducing or avoiding the likelihood of spillage, exposure of the user to vapors or fumes or skin contact skin contact with the ingredients, and reduce the likelihood of injury from handling the system. It has further been discovered that all of the above advantages can be accomplished using a relatively structurally simple system that requires relatively few components.
More specifically, the surgical cement preparation system of the invention in addition to mixing the cement ingredients, can be used to rapidly, accurately, safely and neatly prepare bone cement immediately prior to its delivery to the tissue site. The invention is particularly useful in the preparation of surgical cements, such as polymethylmethacrylate, wherein the system can be used to add a liquid ingredient (e.g. methyl methacrylate) to a dry-state powder ingredient (such as polymethylmethacrylate, barium sulfate or other radiopacifier) together with associated initiators or catalysts, and ensure their thorough mixture and presentation in advance of the cured or hardened state.
The invention provides a surgical cement preparation system for combining a liquid ingredient together with at least one powder ingredient comprising:
The invention also provides a surgical cement preparation system for combining a liquid ingredient together with at least one solid powder ingredient comprising:
The invention also provides a process for preparing an opacified surgical cement using the system comprising the steps of:
The invention further provides a kit comprising the system of the invention, together with additional kit components. The kit can further comprise a spathula. In one embodiment, the ingredients of the surgical cement can be obtained separately and presented at time of use for mixture using the system of the invention. Alternatively, the cement ingredients can be presented in companionship with the system components of the invention. In other words, the liquid ingredient and dry-state powdered ingredient(s) can be contained within the kit comprising the system of the invention. When this kit embodiment is used, the system of the invention further comprises a pre-filled liquid ingredient container accompanying said first vial. Further, the mixing vial can be pre-filled with one or more of the dry-state powdered ingredients, such as an opacifier.
In a preferred embodiment, the system, process and kit of the invention are used to prepare opacified polymethylmethacrylate cement. Accordingly, the liquid ingredient comprises a liquid monomer (e.g., methylmethacrylate) and the dry-state powder ingredients comprise polymethylmethacrylate particles and an opacifier. Other benefits and advantages associated with the invention are explained herein below.
The invention is further illustrated by the following figures, the numerical references of which remain consistent throughout.
The phrases “polymer delivery device” and “polymer delivery barrel” as used herein are meant to refer to a device structured for receipt of surgical cement for subsequent controlled dispensing thereof. Although illustrated herein as a syringe-like container, it will be understood that suitable polymer delivery devices or barrels can take a variety of forms and structures provided that they can receive the mixed surgical cement prepared using the system of the invention.
The phrase “surgical cement” as used herein is meant to refer to the resulting combination of two or more components wherein at least one of the starting materials for said combination is a dry-state material and at least one of the starting materials is a liquid state material. Upon the combining of the components, the combination is initially in liquid state and ultimately cures into a hardened solid state suitable for surgical applications. The phrase “orthopedic cement” is meant to refer to a surgical cement used in association with orthopedic procedures.
Liquid ingredients that can be used for the surgical cement include those biomaterials that, when combined with a dry-state powder ingredient, can harden into a solid form. Preferred for use with the invention is the orthopedic cement polymethylmethacrylate (PMMA). Polymethylmethacrylate is typically prepared by combining a powder ingredient together with a liquid ingredient. The powder ingredient comprises the polymer (i.e., polymethylmethacrylate and copolymers thereof) and initiator (i.e., dibenzoyl peroxide), which can also be presented with a dry-state powder ingredient such as the opacifier. The liquid ingredient comprises the methylmethacrylate monomer and activator or co-initiator ingredient N,N-dimethyl-p-toluidine, or alternatively, 2-(4-(diemthylamino)phenyl)ethanol. The chemical reaction between the powder and liquid ingredients generates polymer chain formation at a rapid rate. The timing of combining the polymethylmethacrylate ingredients (mixing phase) and applying the same prior to the hardening phase is critical to its successful use within a given procedure. It is within such a mixing and delivery scenario that the benefits and advantages of the invention can be fully realized. Further detailed discussion of available bone cements and their chemistry can be found in Kuhn, K.-D., Bone Cements: Up-to-date Comparison of Physical and Chemical Properties of Commercial Materials (Springer-Verlag Publishers, New York) 2000, incorporated herein by reference. Additional ingredients, such as coloring agents and the like, can be added to the components as well.
Various liquid-plus-powder compositions that can be used in conjunction with the invention can be used. Calcium phosphate, calcium carbonate, hydroxyapatite, for example, can be combined into such systems to promote bone ingrowth and enhance antimicrobial properties. Other osteogenic or osteoinductive compositions that can be mixed with a powdered ingredient and are capable of liquid state delivery before hardening can be used as well.
In a preferred embodiment, one of the dry-state powder ingredients to be combined with the liquid ingredient is an opacifier. Opacifiers within the context of the invention are those compounds or compositions that permit visualization of the surgical cement during the medical procedure associated with the application of the surgical cement. Such medical imaging equipment and techniques are readily available to those skilled in the medical arts. Opacifiers that can be used in the invention include, but are not limited to, barium sulfate, bismuth subcarbonate, bismuth sulfate, zirconium dioxide, gold, silver, titanium, tantalum, zirconium, stainless steel, tungsten, and alloys thereof.
Examples of opacified surgical cement compositions that can be used in accordance with the invention include those described in Preissman U.S. Pat. Nos. 6,309,420 and 6,231,615, the entire texts of which are incorporated herein by reference.
One powder ingredient that can be used is composed of methylmethacrylate polymer in an amount of about 79.6% w/w, methylmethacrylate-styrene copolymer in an amount of about 19.9% w/w and benzoyl peroxide in an amount of about 0.5% w/w. One liquid ingredient that can be used is composed of methylmethacrylate monomer in an amount of about 95.05% v/v, ethylene dimethacrylate monomer in an amount of about 4.28% v/v, dimethyl-p-toluidine in an amount of about 0.67% v/v, hydroquinone in an amount of about 20±5 ppm, and 4-methoxyphenol in an amount of about 12 ppm.
The dry-state powdered ingredients to be mixed can be presented a variety of ways. For example when using polymethylmethacrylate cement, the powdered polymethylmethacrylate ingredient can be contained within a separate pouch to be opened and added into the mixing vial or, alternatively, can be within a pre-filled mixing vial alone or alongside a second powder ingredient, e.g., opacifier. The system of the invention affords the capability to present the cement ingredients in an efficient manner that facilitates their safe and rapid handling.
As shown in
These two components contain important features of the invention. The structure of the needle 21 itself directs the liquid component being added into the mixing vial 30 intimately into the midst of the powder placed therein. When a plurality of lateral openings are on the needle (24 and 24′) which is preferred, thorough mixing of the liquid into the resident powder is even further enhanced and expedited. During this combining step of preparing the cement, the opening of the mixing vial 30 is restricted so as to reduce the likelihood of spillage or splashing of the ingredients, and helps contain fumes or vapors that can be associated with the liquid ingredient.
Turning now to
In one embodiment, the cement components, i.e., the liquid ingredient and powdered ingredient(s), can be presented in conjunction with the device components of the invention as part of the kit. Alternatively, the cement ingredients can be obtained and presented separately by the user and then used in conjunction with the system of the invention.
In either case, the liquid ingredient can be presented as contained within a pre-filled liquid container. When the surgical cement is polymethylmethacrylate, the liquid monomer ingredient (methylmethacrylate and associated initiators, catalysts) can be presented within a breakable (glass) ampule as shown in
Referring now to
The first vial 1 can be composed of glass or plastic, and is preferably composed of a material that is substantially non-reactive with the liquid component to be mixed. For example, both the cap 12 and the container 11 of the first vial 1 can be composed of polypropylene. The first vial container 11 can be composed of a flexible plastic material, so that the first vial itself can be flexed to snap the neck of a glass ampule. Thus, upon removing the cap 12, the opening through which to withdraw the liquid is exposed, and the first vial 1 can be recapped for disposal—throughout which the user need not ever directly contact either the liquid or its container.
Referring now to
The syringe 204 comprises a syringe barrel 205 and plunger 206 assembly. In a preferred embodiment of the system of the invention, the syringe barrel 205 and plunger 206 are composed of a material that is chemically compatible with the liquid component. By chemically compatible, it is meant that the materials used for the syringe are substantially non-reactive with respect to the ingredients of the liquid components so as to avoid undesired chemical reactions, e.g., degradation, of the syringe component and potential introduction of undesired compounds into the surgical cement. Both the syringe barrel 205 and the plunger 206 can be constructed from polypropylene, unlike conventional syringes wherein the plunger contains an elastomeric rubber component that contacts the drawn liquid.
Referring now to
The system of the invention can be adapted for use with a contemplated polymer delivery device or, alternatively, can itself further comprise a polymer delivery barrel 50 (see
The funnel 40 component of the invention can be structured to fixedly and removably couple to both the dimensions of the open ends of the mixing vial 30 and the receiving area 51 of a polymer delivery barrel 50. By fixed and removable coupling, the exterior or outer surface 41 of the funnel body 42 is structured to engage and provide a tightened and secured fit within the rim of a container opening (as shown in
Referring to
The invention further includes a kit comprising the system of the invention together with at least one additional component. Additional components can further include, but are not limited to, component holding tray for partially or fully separated device components of the system (as illustrated in
The following example illustrates a process of preparing surgical cement using one embodiment of the components of the system of the invention and how these components can be used in relation to one another.
A kit comprising the system of the invention can be presented as shown in
In the first step and as shown in
In the second step and as shown in
The first vial 1 can itself be used to house the liquid container during shipping and handling and presented with the liquid container therein in accordance with one embodiment of the kit. This is especially advantageous in the case of a liquid container material susceptible to impact breakage, e.g., glass ampules.
In the third step and as shown in
The needle 21 used in the system according to the invention is specifically structured to facilitate a thorough introduction of the liquid ingredient into the dry powder ingredient(s). The distal end 25 of the needle 21 comprises at least one lateral opening 24 (preferably two openings 24 and 24′ as shown) that direct the liquid in multiple directions within the powder upon application of force. As time is of the essence in preparing surgical cement, this feature of the invention further facilitates rapid mixture of the cement ingredients.
In addition to minimizing exposure to liquid fumes, the syringe and needle assembly 20 together with the secondary cap 38 and relatively small second opening 39 of the mixing vial cap 37, collectively enhance the user's control over the transfer and admixture of the liquid ingredient. The rounded distal tip 23 of the needle 21, which can be rounded or dull as compared to conventional sharp needles, avoids accidental puncture injury. The likelihood of unintentional contact with the liquid itself can be avoided or reduced using the system of the invention.
Once the liquid is dispensed in the mixing vial 30, the second cap 38 is re-attached to the mixing vial cap 37. The mixing vial 30 and its contents can then be agitated or shaken to finalize the mixing of the cement.
In the fourth step and as shown in
Once mixed, the cement mixture (illustrated in
The curable polymer mixing system of the invention is useful in surgical procedures involving advanced preparation of ingredients wherein such ingredients must be thoroughly mixed within a relatively short time period and wherein before combining the ingredients they are presented in differing physical states, i.e., liquid and powder. The system of the invention is particularly useful in preparing curable bone cements that emit harmful vapors, fumes or residues during their handling and preparation, such as polymethylmethacrylate cement.
The invention herein above has been described with reference to various and specific preferred embodiments and techniques. It will be understood, however, that reasonable variations and modifications of such embodiments can be made without significantly departing from either the spirit or scope of the invention as defined by the following claims.