1. Field of the Invention
The present invention relates to a device, a kit and a method for mixing and dispensing a bone cement mixture.
2. Description of Related Art
There is a clinical need to fill and stabilize damaged bones of patients, such as for example, filling defects in collapsed vertebra of patients suffering from severe back pain caused by osteoporosis, metastatic tumors or back injuries. Currently, these defects are repaired using multi-component bone cements that are mixed in open containers, transferred to a device and injected into the damaged bone where the mixture chemically reacts or cures to form a solid support structure.
The most widely used bone cements are based on polymethylmethacrylate (PMMA) and hydroxyapatite. These materials have relatively good strength characteristics, but have a number of drawbacks. These cements are a two-part chemically reactive system and have approximately five to ten minutes of working time once the components are mixed. As for example with the PMMA based system, one of the components is a liquid monomer methylmethacrylate (MMA), which is noxious and toxic to handle. The other component, the polymer component PMMA, is a powder that can be difficult to mix thoroughly. Moreover, current methods of mixing these two components together are typically done by hand in an open container or dish. This procedure permits significant vaporization of the noxious liquid monomer MMA. Also, the working time increases between mixing and dispensing because once the mixture is mixed it then needs to be transferred to a syringe for injection into the damaged bone. Moreover, the working time is limited because the viscosity of the cement constantly increases during mixing, thus making transferring of the mixture to the syringe and injection of the mixture into the damaged bone more difficult. Often, very high injection pressures and/or large bore needles may be necessary to inject the mixture, especially if it's near the end of the cements working time.
Thus, there is a need to provide a device for both mixing and dispensing a bone cement mixture.
Embodiments of the present invention provide a device, a kit and a method that facilitates mixing and dispensing of the bone cement mixture such that the interventionalist and the patient have minimal exposure to the noxious vapors of the monomer as well as providing more flexible working times for suitable injection-ability of the mixture into the damaged bone.
In at least one embodiment of the present invention, a device for mixing and dispensing a bone cement mixture is provided. The device comprises a housing having a longitudinal axis and a chamber formed within the housing for containing a first bone cement component. The housing has a distal end and a proximal end. An outlet at the distal end is in fluid communication with the chamber for receiving a second bone cement component and for dispensing the bone cement mixture from the device. A plunger is disposed cooperatively within the chamber and configured to actuate within the chamber, along the longitudinal axis. The plunger includes a plunger rod having a first end and a second end. A plunger rod includes a piston at the first end and a plunger handle at the second end configured to actuate the plunger within the chamber. A mixing element is disposed adjacent the piston. The plunger is configured to rotate the mixing element about the longitudinal axis to mix the first and second bone cement components together to form the bone cement mixture. The plunger is also configured to advance through the chamber from the proximal end toward the distal end. As the plunger advances through the chamber, the piston is configured to receive the mixing element and dispense the bone cement mixture from the chamber through the outlet.
In at least another embodiment of the present invention, a device for mixing and dispensing a bone cement mixture is provided. The device comprises a housing having a longitudinal axis and a chamber formed within the housing for containing a first bone cement component. The housing has a distal end and a proximal end. An outlet at the distal end is in fluid communication with the chamber for receiving a second bone cement component and for dispensing the bone cement mixture from the device. A plunger is disposed cooperatively within the chamber and configured to actuate within the chamber, along the longitudinal axis. The plunger includes a plunger rod having a first end and a second end. A plunger rod includes a piston at the first end and a plunger handle at the second end configured to actuate the plunger within the chamber. A mixing element is disposed adjacent the piston and configured to rotate about the longitudinal axis to mix the first and second bone cement components together to form the bone cement mixture. Turning the plunger handle in a first direction is configured to rotate the mixing element to mix the cement mixture. Turning the plunger handle in a second direction is configured to advance the plunger through the chamber from the proximal end toward the distal end. The piston is configured to receive the mixing element and dispense the bone cement mixture from the chamber through the outlet.
In at least another embodiment of the present invention, a bone cement substitute kit for mixing a bone cement mixture and dispensing the bone cement mixture into a damaged bone of a patient is provided. The kit comprises a first bone cement component and a second bone cement component. The kit further comprises a device including a housing having a longitudinal axis and a chamber formed within the housing for containing a first bone cement component. The housing has a distal end and a proximal end. An outlet at the distal end is in fluid communication with the chamber for receiving a second bone cement component and for dispensing the bone cement mixture from the device. A plunger is disposed cooperatively within the chamber and configured to actuate within the chamber. The plunger includes a plunger rod having a first end and a second end. The plunger rod includes a piston at the first end and a plunger handle at the second end configured to actuate the plunger within the chamber.
A mixing element is disposed adjacent the piston. The plunger is configured to rotate the mixing element about the longitudinal axis to mix the first and second bone cement components together to form the bone cement mixture. The plunger is also configured to advance through the chamber from the proximal end toward the distal end. As the plunger advances through the chamber, the piston is configured to receive the mixing element and dispense the bone cement mixture from the chamber through the outlet. The kit further comprises a needle in fluid communication with the outlet and configured to receive the bone cement mixture from the device and advance the cement mixture into the damaged bone of the patient.
In at least another embodiment of the present invention, a method for mixing a bone cement mixture and for dispensing the bone cement mixture into a damaged bone of a patient is provided. The method comprises providing a device including a housing having a longitudinal axis and a chamber formed therein. The housing has a distal end and a proximal end. An outlet at the distal end is in fluid communication with the chamber. A plunger is disposed cooperatively within the chamber and configured to actuate within the chamber. The plunger includes a plunger rod having a piston at a first end and a plunger handle at a second end. A mixing element is disposed adjacent the piston and configured to rotate about the longitudinal axis to mix the first and second bone cement components together to form the bone cement mixture.
The method further comprises introducing a first bone cement component and a second bone cement component into the chamber. A needle in fluid communication with the device is inserted into the damaged bone of the patient. The first bone cement component is mixed with the second bone cement component which includes actuating the plunger to rotate the mixing element about the longitudinal to mix the first and second bone cement components together to form the bone cement mixture. The bone cement mixture is dispensed into the damaged bone of the patient via the needle which includes actuating the plunger to advance through the chamber. As the plunger advances through the chamber, the piston receives the mixing element and dispenses the bone cement mixture from the chamber through the outlet. The bone cement is cured to stabilize the damaged bone of the patient.
Further objects, features and advantages of the invention will become apparent from consideration of the following description and the appended claims when taken in connection with the accompanying drawings.
a is a side view of a device for stabilizing a collapsed vertebra in accordance with another embodiment of the present invention;
b is a perspective view of a device for stabilizing a collapsed vertebra in accordance with another embodiment of the present invention;
c is a side view of the device depicted in
d is a an end view of the device depicted in
e is a cross section of the device depicted in
a is a side view of a bone cement substitute kit in accordance with one embodiment of the present invention;
b is an exploded view of the bone cement substitute kit depicted in
Detailed embodiments of the present invention are disclosed herein. It is understood however, that the disclosed embodiments are merely exemplary of the invention and may be embodied in various and alternative forms. The figures are not necessarily to scale; some figures may be configured to show the details of a particular component. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a representative basis with the claims and for teaching one skilled in the art to practice of the present invention.
Examples of the present invention seek to overcome some of the concerns associated with stabilizing and/or repairing the damaged bone of a patient with a bone cement while minimizing toxic effects to both the patient and the interventionalist, and enhancing the ease of handling of the bone cement for both mixing and dispensing into the damaged bone.
Employing the principles of the present invention is, for example, a device, a kit, and a method for stabilizing and/or repairing a damaged bone of a patient. The device, which is utilized in both the kit and the method, is a closed mixing and dispensing system having a housing and a chamber formed therein for containing, for example, a first bone cement component. The housing includes an outlet in fluid communication with the chamber for receiving, for example, a second bone cement component. The device further includes a plunger disposed within the chamber configured to actuate within the chamber. The plunger includes a piston and a mixing element is disposed adjacent the piston. The mixing element is configured rotate within the housing to mix the first and second bone cement components together to form the bone cement mixture. The plunger is configured to actuate within the housing to advance the piston through the chamber.
As the piston advances through the chamber, the piston receives the mixing element and dispenses the bone cement mixture from the chamber through the outlet. The device may also be in fluid communication with a needle inserted into the damaged bone of a patient. The device is configured such that the bone cement mixture may be advanced from the device into the damaged bone of a patient via the needle. The device preferably mixes the bone cement components together without releasing noxious monomer fumes contained in one of the bone cement components. Moreover, since the device is configured to dispense the bone cement mixture there is no need for transferring the mixture from another source into the device. Accordingly, the device minimizes the mixing and dispensing time of the bone cement and thus, enhances the remaining working time for introducing the mixture into the damaged bone. Once the bone cement is introduced into the damaged bone of the patient it cures to form a solid structure which stabilizes the bone.
Referring now to the drawings,
Referring now to
Vertebroplasty involves that a patient remain lying throughout the entire procedure. It is performed under a local anesthesia and/or a light sedative. A small nick is then made in the skin near the spine and a needle 14 is inserted percutaneously. As illustrated in
Referring to
Referring to
To further illustrate, component A, for example, is a solid polymer powder of PMMA preloaded into the chamber 24 by the manufacturer of the device 20 and component B is a liquid monomer MMA with a relatively low viscosity of about 0.6 centipoise at room temperature. The MMA could be poured from an external container into the housing 22 prior to assembly of the device 20 or alternatively, injected into the outlet 30, via a syringe, through a luer fitting nozzle 56 at the distal end 28 of the housing 22. When the MMA is mixed with the PMMA, a chemically reacting paste may be formed which continually increases in viscosity over a working time of about 5 to 10 minutes to form a solid structure. In another example, component A may be sodium phosphate and component B may be solid powder of monocalcium phosphate, tricalcium phosphate, calcium carbonate or mixtures thereof that form a chemically reacting solution when mixed with sodium phosphate, which also increases in viscosity over a working time of about 5 to 10 minutes to form a solid structure.
In this embodiment, the device 20 further comprises a plunger 34 disposed within the chamber 24 and configured to actuate within the chamber 24. For example, the plunger 34 actuates by sliding within the chamber 24 towards the distal end 28 of the chamber 24. Preferably, the plunger 34 is a screw-gear plunger. The screw-gear plunger 34 includes a plunger rod 36 having a distal end 38 and a proximal end 40. In this embodiment, the screw-gear plunger 34 includes a piston 42 disposed at the distal end 38 of the plunger rod 36 and a plunger handle 44 at the proximal end 40 of the plunger rod 36. The piston 42 includes a seal member 43 between the piston 42 and the chamber 24 for preventing bone cement from flowing therebetween and to facilitate movement of the piston 42 within the chamber 24. Preferably, the seal member 43 comprises an o-ring. The plunger rod 36 includes male threads or grooves 46 formed thereon.
In this embodiment, a mixing element 48 is disposed adjacent the piston 42 and configured to rotate about the longitudinal axis A to mix the first and second bone cement components together within the chamber 24 to form the bone cement mixture 18. The mixing element 48 includes a structure to promote mixing of the bone cement components, such as a mixing paddle having a plurality arms 50 defining a plurality of apertures 49. As illustrated in
In a preferred embodiment, the chamber 24, which is configured to receive the screw-gear plunger 34 at its proximal end 26, is a high pressure injection chamber. The high pressure injection chamber 24 is adapted for withstanding positive displacement pressures associated with advancing “paste like” fluids through the outlet 30. In one example, the viscosity of the “paste like” fluid is greater than about 1,000 centipoise. The high pressure chamber 24 is preferably made of a plastic, such as polycarbonate, but may be made of glass or other suitable materials known in the art.
In this embodiment, the device 20 includes an injector handle 32 for gripping the device 20 by an interventionalist. The injector handle 32 supports the housing 22, and thus the high pressure chamber 24, at its proximal end 26. As shown in
In this embodiment, the screw-gear plunger 34 is used to mix the bone cement components to form the bone cement mixture as well as dispense the bone cement mixture from the device 20. In this embodiment, the screw-gear plunger 34 enters the opening 52 formed within the injector handle 32. Preferably, the grooves 46 of the plunger rod 36 do not extend along the entire length of the plunger rod 36. For example, the distal end 38 of the plunger rod 36 includes a non-grooved portion 39 which does not have any grooves disposed thereon. In this embodiment, the opening 52 is a threaded opening having female threads configured to engage/disengage the grooves 46 of the plunger rod 36 and thereby adjust the device 20 between a disengaged position and an engaged position.
In this embodiment, the threaded opening 52 initially receives the non-grooved portion 39 of the plunger rod 36, defining the disengaged position. In the disengaged position, an interventionalist turns the plunger handle 44 to actuate the screw-gear plunger 34 to rotate the mixing element 46 about the longitudinal axis A within the chamber to mix the bone cement components together. The process of rotating the mixing element 48 to mix the bone cement mixture within the high pressure injection chamber 24 may be repeated until the bone cement components are thoroughly mixed together to the satisfaction of the interventionalist.
In a preferred embodiment, the device 20 is adjusted to the engaged position by pushing or nudging the screw-gear plunger 34 forward, in the direction of arrow 57, so that the threaded opening 52 engages the grooves 46 of the plunger 36. In the engaged position, the interventionalist turns the plunger handle 44 and the threaded opening 52 cooperates with the grooves 46 to advance the screw-gear plunger 34, and thus the piston 42, through the high pressure injection chamber 24 towards the distal end 28 of the housing 22. As the screw-gear plunger 34 advances towards the distal end 28 of the housing 22, the piston 42 receives the mixing element 48 and advances the bone cement mixture from the high pressure injection chamber 24 through the outlet 30, thereby dispensing the mixture from the device 20. Simultaneously, turning the plunger handle 44 when the device 20 is in the engaged position may also rotate the mixing element 48 as the plunger 34 is advanced.
In a preferred embodiment, turning the plunger handle 44 in a first direction, for example a counter-clockwise direction 53, when the device 20 is in the disengaged position, actuates the screw-gear plunger 34 to rotate the mixing element 46 about the longitudinal axis A within the chamber 24 to mix the bone cement components together. Whereas, turning the plunger handle 44 in a second direction, for example a clockwise direction 55, when the device 20 is in the engaged position, actuates the screw-gear plunger 34 to advance through the chamber 24. In this embodiment, the threaded opening 52 and the grooved portion of the plunger rod 36 may be configured to engage and cooperate to advance the screw-gear plunger 34 through the chamber 24 only when the plunger handle 44 is turned in the second direction. This acts as a safety mechanism to prevent inadvertent advancement of the screw-gear plunger 34 through the chamber when the intervertionalist turns the plunger handle 44 in the first direction to mix the bone cement mixture. Thus, the interventionalist is thereby prevented from prematurely dispensing an insufficiently mixed bone cement mixture.
The foregoing embodiments have been given solely by way of example. It will be understood by those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention. For example, the device 20 may include any suitable engagement/disengagement mechanism which allows rotation of the mixing element 48 (i.e., mixing of the bone cement mixture) when the plunger handle 44 is turned in one direction and allows advancement of the screw-gear plunger 34 (i.e., dispensing of the bone cement mixture) when the plunger handle 44 is turned in another direction.
The device 20 may further include as part of the outlet 30, a luer fitting nozzle 56. The bone cement mixture may be dispensed from the outlet 30 of the device 20 through the luer fitting nozzle 56. In this example, the luer fitting nozzle 56 typically has a tapered end 59 that facilitates connecting to various types of cannula, tubing, needles or other similar medical devices.
In at least one embodiment, the plunger handle 44 of the screw-gear plunger 34 is positioned along the plunger rod 36 and disposed outside of the high pressure chamber 24 and has, for example, a cylindrical shape and a plurality of gripping indents 45 for facilitating gripping and turning of the screw-gear plunger 34 by the interventionalist.
Referring to
In this embodiment, the balloon 66 may be made of any suitable material used for medical intracorporeal balloon devices. However, a polymer impermeable to body fluids and MMA may be preferred. An example of such material is polyethylene terephthalate (PET) or polybutylene terephthalate (PBT).
The interventionalist may also assess whether the collapsed vertebra 12 is sufficiently filled via fluoroscopy. If the collapsed vertebra 12 is not sufficiently filled, an additional balloon may be placed within the collapsed vertebra 12 and the filling, solidifying and/or curing and sealing steps may be repeated.
Referring also to
The kit may further comprise a sealed envelope 74 containing a component of the bone cement, such as PMMA, and sealed container 76 containing the other component of the bone cement, such as MMA. Alternatively, either of the first and second components of the bone cement may already be contained within the chamber 24 of the device 20 as packaged. The device 20 may include a valve which closes off fluid communication between the chamber 24 and the outlet 30 to facilitate packaging and handling of the kit when a bone cement component is pre-packaged within the chamber 24. Additionally, the kit may further include a balloon 66 (shown in
Referring to
A first bone cement component and a second bone cement component are introduced (104) into a chamber.
A needle is inserted (106) into the damaged bone of the patient. The needle is in fluid communication with the apparatus.
The first and second bone cement components are mixed together (108) to form a bone cement mixture. This includes actuating a plunger to rotate a mixing element about a longitudinal axis to mix the bone cement components. Actuating the plunger to rotate the mixing element may include positioning a plunger rod in a disengaged position and turning a plunger handle in a first direction.
The bone cement mixture is dispensed from the device into the damaged bone of the patient via the needle (110). This includes actuating the plunger to advance a piston through the chamber of the device, where the piston receives the mixing element and advances the bone cement mixture from the chamber and through the needle. Actuating the plunger to advance a piston through the chamber of the device may include positioning a plunger rod in an engaged position and turning the plunger handle in a second direction. The bone cement mixture is then allowed to cure (112) to stabilize the damaged bone of a patient.
The method may further comprise positioning a balloon within the damaged bone of the patient, wherein dispensing the bone cement mixture includes receiving the bone cement mixture into the balloon via the needle.
As a person skilled in the art will readily appreciate, the above description is meant as an illustration of the implementation of the principles of this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification variation and change, without departing from the spirit of this invention, as defined in the following claims.
Number | Date | Country | |
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Parent | 12119155 | May 2008 | US |
Child | 13673020 | US |