Source: http://www.google.es/patents/US8487021
Timestamp: 2018-01-16 08:13:51
Document Index: 607074576

Matched Legal Cases: ['§119', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'art, 2003', 'Application No. 09', 'Application No. 09']

Patente US8487021 - Bone treatment systems and methods - Google Patentes
The present disclosure relates to bone cement formulations that have an extended working time for use in vertebroplasty procedures and other osteoplasty procedures together with cement injectors that include energy delivery systems for on-demand control of cement viscosity and flow parameters. The bone...http://www.google.es/patents/US8487021?utm_source=gb-gplus-sharePatente US8487021 - Bone treatment systems and methods
Número de publicación US8487021 B2
Número de solicitud US 12/395,532
También publicado como EP2252336A2, EP2252336B1, EP2810664A1, US9216195, US20090247664, US20140031450, US20160058906, WO2009108893A2, WO2009108893A3
Número de publicación 12395532, 395532, US 8487021 B2, US 8487021B2, US-B2-8487021, US8487021 B2, US8487021B2
Inventores Csaba Truckai, Andrew Kohm, John Shadduck, Robert Luzzi
Citas de patentes (215), Otras citas (44), Citada por (6), Clasificaciones (21), Eventos legales (4)
US 8487021 B2
a liquid component and a non-liquid component that, upon mixing, provide a polymerizable bone cement composition, the liquid component comprising at least one monomer and the non-liquid component comprising at least a polymer and an initiator;
wherein the non-liquid component is configured to provide controlled differential exposure of the initiator to the liquid monomer so as to control the viscosity of the bone cement composition and further comprises;
a first volume of polymer particles having a mean diameter less than 100 μm and on the basis of the total weight of the first volume of polymer particles, greater than or equal to 1.1 wt. % of the initiator being contained within the first volume;
a second volume of polymer particles having a mean diameter greater than 100 μm and on the basis of the total weight of the second volume of polymer particles, greater than or equal to 0.9 wt. % of the initiator being contained within the second volume; and
a third volume of polymer particles having a mean diameter less than 100 μm and on the basis of the total weight of the third volume of polymer particles, wherein 0-1.1 wt. % of the initiator is contained within the third volume,
wherein the wt. % of the initiator is different in each of the first, second, and third volumes of polymer particles.
2. The bone cement composition of claim 1, wherein the non-liquid component is configured to provide at least two time intervals in which exposure of the initiator to the liquid monomer is substantially the same.
3. The bone cement composition of claim 1, wherein the non-liquid component is configured to provide first and second time intervals in which exposure of the initiator to the liquid monomer is substantially different.
4. The bone cement composition of claim 1, wherein the non-liquid component is configured to provide first, second and third time intervals in which exposure of the initiator to the liquid monomer is substantially different.
5. The bone cement composition of claim 1, wherein the non-liquid component is configured to provide an initial time interval in which exposure of the initiator to the liquid monomer is substantially higher than a subsequent time interval.
6. The bone cement composition of claim 1, wherein the initiator is distributed within the polymer component so as to selectively be exposed to the liquid monomer component over at least a first and a second selected time intervals.
7. The bone cement composition of claim 2, wherein a greater volume of initiator is exposed to the liquid monomer during a first time interval than a second time interval.
8. The method bone cement composition of claim 2, wherein a greater volume of initiator is exposed to the liquid monomer during a third time interval than a second time interval.
9. The bone cement composition of claim 2, wherein the first time interval comprises at least 1 minute.
10. The bone cement composition of claim 2, wherein the first time interval comprises less than 5 minutes.
11. The bone cement composition of claim 1, wherein the initiator is benzoyl peroxide (BPO).
12. The bone cement composition of claim 1, wherein the monomer comprises methyl methacrylate (MMA) and the polymer comprises polymethyl methacrylate (PMMA).
13. The bone cement composition of claim 1, wherein the non-liquid component comprises particles of benzoyl peroxide (BPO) integrated into the polymer particles.
14. The bone cement composition of claim 1, wherein the bone cement composition exhibits a viscosity of at least 500 Pa·s within about 30-90 sec after the liquid and non-liquid components are substantially mixed with one another.
15. The bone cement composition of claim 1, wherein the initiator comprises benzoyl peroxide (BPO).
16. The bone cement composition of claim 15, wherein the total concentration of BPO contained within the first and second volumes of polymer particles ranges between about 0.5 to 5 wt. %, on the basis of the total weight of the polymer component.
17. The bone cement composition of claim 1, wherein the molecular weight of the first volume of polymer particles is within the range between about 300,000 to about 500,000.
18. The bone cement composition of claim 1, wherein the amount of the first volume of polymer particles is within the range between about 30 wt. % to about 40 wt. % on the basis of the total weight of the polymer particles.
19. The bone cement composition of claim 1, wherein the mean diameter of particles in the first volume of polymer particles is within the range between about 70 μm to about 90 μm.
20. The bone cement composition of claim 1, wherein the molecular weight of the second volume of polymer particles is within the range between about 150,000 to about 350,000.
21. The bone cement composition of claim 1, wherein the amount of the second volume of polymer particles is within the range between about 40 wt. % to about 50 wt. % on the basis of the total weight of the polymer particles.
22. The bone cement composition of claim 1, wherein the mean diameter of particles in the second volume of polymer particles is within the range between about 100 μm to about 120 μm.
23. The bone cement composition of claim 1, wherein the molecular weight of the third volume of polymer particles is within the range between about 250,000 to about 450,000.
24. The bone cement composition of claim 1, wherein the mean diameter of particles in the third volume of polymer particles is within the range between about 25 μm to about 45 μm.
25. The bone cement composition of claim 1, wherein the non-liquid component further comprises zirconium dioxide or barium sulfate.
26. The bone cement composition of claim 1, wherein the liquid component comprises:
about 98.0 wt. % to about 99.9 wt. % methylmethacrylate (MMA);
about 0.15 wt. % to about 0.95 wt. % N, N-dimethyl-p-toluidine (DMPT); and
about 30 ppm to about 150 ppm hydroquinone (HQ);
wherein the amounts of the liquid components are on the basis of the total weight of the liquid component.
27. The bone cement composition of claim 15, wherein the molecular weight of the first volume of polymer particles is within the range between about 300,000 to about 500,000.
28. The bone cement composition of claim 15, wherein the amount of the first volume of polymer particles is within the range between about 30 wt. % to about 40 wt. % on the basis of the total weight of the polymer particles.
29. The bone cement composition of claim 15, wherein the mean diameter of particles in the first volume of polymer particles is within the range between about 70 μm to about 90 μm.
30. The bone cement composition of claim 15, wherein the molecular weight of the second volume of polymer particles is within the range between about 150,000 to about 350,000.
31. The bone cement composition of claim 15, wherein the amount of the second volume of polymer particles is within the range between about 40 wt. % to about 50 wt. % on the basis of the total weight of the polymer particles.
32. The bone cement composition of claim 15, wherein the mean diameter of particles in the second volume of polymer particles is within the range between about 100 μm to about 120 μm.
33. The bone cement composition of claim 15, wherein the molecular weight of the third volume of polymer particles is within the range between about 250,000 to about 450,000.
34. The bone cement composition of claim 15, wherein the mean diameter of particles in the third volume of polymer particles is within the range between about 25 μm to about 45 μm.
35. The bone cement composition of claim 15, wherein the non-liquid component further comprises zirconium dioxide or barium sulfate.
36. The bone cement composition of claim 15, wherein the liquid component comprises:
37. The bone cement composition of claim 1, wherein:
the first volume of polymer particles has a mean diameter in the range of 70-90 μm;
the second volume of polymer particles has a mean diameter in the range of 100-120 μm; and
the third volume of polymer particles has a mean diameter in the range of 25-45 μm.
38. The bone cement composition of claim 1, wherein
1.1-1.3 wt. % of the initiator is contained within the first volume of polymer particles;
0.9-1.1 wt. % of the initiator is contained within the second volume of polymer particles; and
0-1.1 wt. % of the initiator is contained within the third volume of polymer particles.
39. The bone cement composition of claim 1, wherein:
the first volume of polymer particles possesses a molecular weight within the range between 300,000 to 500,000;
the second volume of polymer particles possesses a molecular weight within the range between 150,000 to 350,000; and
the third volume of polymer particles possesses a molecular weight within the range between 250,000 to 450,000.
40. The bone cement composition of claim 1, wherein:
the first volume of particles is 30-40% of the polymer particles on the basis of the total weight of the polymer particles;
the second volume of particles is 40-50% of the polymer particles on the basis of the total weight of the polymer particles; and
the third volume of particles is 10-30% of the polymer particles on the basis of the total weight of the polymer particles.
This application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application Nos. 61/067,479, filed on Feb. 28, 2008, entitled Bone System Treatment Systems and Methods, 61/067,480, filed on Feb. 28, 2008, entitled Bone System Treatment Systems and Methods, 61/124,336, filed on Apr. 16, 2008, entitled Bone Treatment Systems and Methods, filed Aug. 28, 2008, entitled Bone Treatment Systems and Methods, and 61/124,338 filed Apr. 16, 2008, entitled Bone Treatment Devices and Methods, the entire contents of both of which are hereby incorporated by reference and should be considered a part of this specification.
Embodiments of the present disclosure relate to bone cements and cement injection systems, and in certain embodiments, systems and methods for on-demand control of bone cement viscosity for treating vertebral compression fractures and for preventing cement extravasation.
Osteoporotic fractures are prevalent in the elderly, with an annual estimate of 1.5 million fractures in the United States alone. These include 750,000 vertebral compression fractures (VCFs) and 250,000 hip fractures. The annual cost of osteoporotic fractures in the United States has been estimated at $13.8 billion. The prevalence of VCFs in women age 50 and older has been estimated at 26% and increases with age, reaching 40% among 80+ year-old women. Medical advances aimed at slowing or arresting bone loss from aging have not provided solutions to this problem, however. Further, the population affected grows steadily as life expectancy increases. Osteoporosis affects the entire skeleton but most commonly causes fractures in the spine and hip. Spinal or vertebral fractures also cause other serious side effects, with patients suffering from loss of height, deformity and persistent pain which can significantly impair mobility and quality of life. Fracture pain usually lasts 4 to 6 weeks, with intense pain at the fracture site. Chronic pain often occurs when one vertebral level is greatly collapsed or multiple levels are collapsed.
Vertebroplasty and kyphoplasty are recently developed techniques for treating vertebral compression fractures. Percutaneous vertebroplasty was first reported by a French group in 1987 for the treatment of painful hemangiomas. In the 1990's, percutaneous vertebroplasty was extended to indications including osteoporotic vertebral compression fractures, traumatic compression fractures, and painful vertebral metastasis. Vertebroplasty is the percutaneous injection of polymethyl methacrylate (PMMA) into a fractured vertebral body via a trocar and cannula. The targeted vertebrae are identified under fluoroscopy and a needle is introduced into the vertebrae body, under fluoroscopic control, to allow direct visualization. A bilateral transpedicular (through the pedicle of the vertebrae) approach is typical but the procedure can be done unilaterally. The bilateral transpedicular approach allows for more uniform PMMA infill of the vertebra.
Leakage of PMMA during vertebroplasty can result in very serious complications including compression of adjacent structures that necessitate emergency decompressive surgery. See “Anatomical and Pathological Considerations in Percutaneous Vertebroplasty and Kyphoplasty: A Reappraisal of the Vertebral Venous System”, Groen, R. et al, Spine Vol. 29, No. 13, pp 1465-1471 2004. Leakage or extravasation of PMMA is a critical issue and can be divided into paravertebral leakage, venous infiltration, epidural leakage and intradiscal leakage. The exothermic reaction of PMMA carries potential catastrophic consequences if thermal damage were to extend to the dural sac, cord, and nerve roots. Surgical evacuation of leaked cement in the spinal canal has been reported. It has been found that leakage of PMMA is related to various clinical factors such as the vertebral compression pattern, and the extent of the cortical fracture, bone mineral density, the interval from injury to operation, the amount of PMMA injected and the location of the injector tip. In one recent study, close to 50% of vertebroplasty cases resulted in leakage of PMMA from the vertebral bodies. See Hyun-Woo Do et al, “The Analysis of Polymethylmethacrylate Leakage after Vertebroplasty for Vertebral Body Compression Fractures”, Jour. of Korean Neurosurg. Soc. Vol. 35, No. 5 (May 2004) pp. 478-82.
Another life-threatening complication of vertebroplasty is pulmonary embolism. See Bernhard, J. et al, “Asymptomatic diffuse pulmonary embolism caused by acrylic cement: an unusual complication of percutaneous vertebroplasty”, Ann. Rheum. Dis. 2003; 62:85-86. The vapors from PMMA preparation and injection also are cause for concern. See Kirby, B, et al., “Acute bronchospasm due to exposure to polymethylmethacrylate vapors during percutaneous vertebroplasty”, Am. J. Roentgenol. 2003; 180: 543-544.
In an embodiment, a bone cement composition is provided. The composition comprises a liquid component and a non-liquid component that, upon mixing, provide a polymerizable bone cement composition. The liquid component comprises at least one monomer and the non-liquid component comprises at least a polymer and an initiator. The non-liquid component is configured to allow controlled exposure of the initiator to the liquid monomer so as to control the viscosity of the bone cement composition over a working time in which the cement is injected into bone.
In another embodiment, a bone cement composition is provided. The bone cement composition comprises a monomer component and a polymer component. The polymer component comprises a first volume of polymer particles and a second volume of polymer particles. The first volume of polymer particles comprises greater than about 0.5 wt. % BPO and the second volume of polymer particles comprises less than about 0.5 wt. % BPO, on the basis of the total weight of the polymer component.
In a further embodiment, a bone cement composition is provided. The bone cement composition comprises a monomer component and a polymer component. The polymer component comprises particles of at least one polymer and about 0.2 to 3 wt. % benzoyl peroxide (BPO). The BPO is provided in at least two of the following configurations: as a surface coating upon at least a portion of the polymer particles, one or more layers within the interior of the polymer particles, as BPO microcapsules and BPO particles. In certain embodiments, the BPO particles may be integrated into the polymer particles. In other embodiments, the BPO particles may not be integrated into the polymer particles. In further embodiments, the BPO microcapsules may be integrated into the polymer particles.
In an embodiment, a method of treating bone is provided. The method comprises mixing a liquid component and a non-liquid component to provide a polymerizable bone cement composition. The liquid component comprises at least one monomer and the non-liquid component comprises polymer particles and benzoyl peroxide (BPO). The non-liquid component is configured to control the amount of BPO that is exposed to the liquid component as a function of time during polymerization of the bone cement composition.
In a further embodiment, a bone cement composition is provided. The bone cement composition comprises a powder component and a liquid component. The powder component comprises about 45%-55 wt. % polymethylmethacrylate polymer (PMMA), about 25-35 wt. % Zirconium Dioxide or Barium Sulfate, and benzoyl peroxide (BPO), where the amounts of each of the powder components are based upon the total weight of the powder component. The liquid component comprises about 98.0-99.9 wt. % Methylmethacrylate (MMA), about 0.15-0.95 wt. % N, N-dimethyl-p-toluidine (DMPT), and about 30-150 ppm hydroquinone (HQ), where the amounts of the liquid components are on the basis of the total weight of the liquid component.
In another embodiment, a bone cement is provided. The bone cement comprises a first monomer-carrying component and a second polymer-carrying component, wherein post-mixing the mixture of the first and second components is characterized, after an initial exposure period, as having a time-viscosity curve slope of less than or equal to about 200 Pa·s/minute until the mixture reaching a viscosity of about 2000 Pa·s.
In an additional embodiment, a bone cement is provided. The bone cement comprises a first monomer-carrying component and a second polymer-carrying component, wherein post-mixing the mixture is characterized by a time-viscosity curve slope of less than or equal to about 200 Pa·s/minute immediately before the mixture reaches a viscosity of about 1500 Pa·s.
In a further embodiment, a bone cement is provided. The bone cement comprises a first monomer-carrying component and a second polymer-carrying component, wherein post-mixing the mixture of the first and second components is characterized, after an initial exposure period, as having a time-viscosity curve slope of less than or equal to about 1500 Pa·s at about 25 minutes post-mixing.
FIG. 1 is a schematic, perspective view of a bone cement injection system in accordance with one embodiment of the present disclosure;
FIG. 2 is a schematic, exploded side view of the system of FIG. 1, illustrating the bone cement injection components de-mated from one another;
FIG. 3 is a schematic illustration of one embodiment of a thermal emitter component of the system of FIGS. 1 and 2;
FIG. 4 is a schematic, exploded perspective view of a force application and amplification component of the system of FIGS. 1-2 in combination with an embodiment of a pressurization mechanism and in communication with an energy source and a controller;
FIG. 5 is an enlarged, assembly view of an embodiment of the pressurization mechanism of the system of FIG. 4;
FIG. 6 is a perspective view of components of the system of FIGS. 1-5 with a perspective view of an embodiment of an energy source and controller.
FIG. 7 is chart indicating a time-viscosity curve for a prior art PMMA bone cement.
FIG. 8A is diagram indicating the method of utilizing applied energy and an energy-delivery algorithm to accelerate the polymerization of a PMMA bone cement to provide a selected time-viscosity curve.
FIG. 8B is chart indicating a modified time-viscosity curve for a PMMA bone cement of FIG. 7 when modified by applied energy from a thermal energy emitter and a selected energy-delivery algorithm according to an embodiment of the present disclosure.
FIGS. 8C and 8D are images of PMMA bone cement exiting an injector without applied energy and the same PMMA bone cement exiting an injector as modified by applied energy according to one embodiment of energy-delivery algorithm.
FIG. 10 is chart indicating time-viscosity curves for an embodiment of PMMA bone cement as in FIG. 8A at different ambient temperatures.
FIG. 11 is a view of another embodiment of a bone cement injection systems with components de-mated from one another where the system included first and second thermal energy emitters.
FIG. 13 is a plot illustrating the temperature-time behavior of embodiments of the bone cement composition under conditions where the composition is and is not heated.
FIG. 14 is a plot illustrating the viscosity-time behavior of embodiments of the bone cement composition heated to temperatures ranging between about 25° C. to 55° C.
FIG. 15 is chart indicating time-viscosity curves for two embodiments of PMMA bone cement of this disclosure as well as other commercially available PMMA bone cements.
FIG. 16 is a schematic view of polymer beads of an embodiment of a bone cement of the present disclosure.
FIG. 17 is a schematic view of polymer beads of another bone cement embodiment of the present disclosure.
FIG. 18 is a schematic view of polymer beads of a further embodiment of a bone cement of the present disclosure.
FIG. 19 is a schematic view of polymer beads of an additional bone cement embodiment of the present disclosure.
FIG. 20 is a schematic view of polymer beads of another bone cement embodiment of the present disclosure.
FIG. 21 is a chart indicating free indicator (BPO) available to be exposed to monomer over a post-mixing interval of a cement of the present disclosure showing a first positive slope followed by a substantially constant BPO availability.
FIG. 22 is another chart indicating free initiator (BPO) available to be exposed to monomer over a post-mixing interval of a cement of the present disclosure.
FIG. 24 is a schematic view of polymer beads of another bone cement embodiment of the present disclosure.
FIG. 25 is a chart indicating a time viscosity curve of a cement of FIG. 23 over a post-mixing interval.
For purposes of understanding the principles of the embodiments of the present disclosure, reference will now be made to the embodiments illustrated in the drawings and accompanying text. As background, a vertebroplasty procedure using embodiments of the present disclosure may introduce the injector of FIGS. 1-2 through a pedicle of a vertebra, or in a parapedicular approach, for accessing the osteoporotic cancellous bone. The initial aspects of the procedure are similar to percutaneous vertebroplasty, where the patient is placed in a prone position on an operating table. The patient is typically under conscious sedation, although general anesthesia is an alternative. The physician injects a local anesthetic (e.g., about 1% Lidocaine) into the region overlying the targeted pedicle or pedicles, as well as the periosteum of the pedicle(s). Thereafter, the physician may use a scalpel to make an approximately 1 to 5 mm skin incision over each targeted pedicle. Thereafter, the bone cement injector is advanced through the pedicle into the anterior region of the vertebral body, which typically is the region of greatest compression and fracture. The physician confirms the introducer path posterior to the pedicle, through the pedicle and within the vertebral body, by anteroposterior and lateral X-Ray projection fluoroscopic views. The introduction of infill material as described below can be imaged several times, or continuously, during the treatment depending on the imaging method.
The terms “bone cement”, “bone fill”, “bone fill material”, “infill material”, and “infill composition” include their ordinary meaning as known to those skilled in the art and may include any material for infilling a bone that includes an in-situ hardenable or settable cement and compositions that can be infused with such a hardenable cement. The fill material also can include other fillers, such as filaments, microspheres, powders, granular elements, flakes, chips, tubules and the like, autograft or allograft materials, as well as other chemicals, pharmacological agents, or other bioactive agents.
The term “flowable material” includes its ordinary meaning as known to those skilled in the art and may include a material continuum that is unable to withstand any static shear stress and responds with a substantially irrecoverable flow (e.g., a fluid), unlike an elastic material or elastomer that responds to shear stress with a recoverable deformation. Flowable materials may include fill materials or composites that may include a first, fluid component alone or in combination with an second, elastic, or inelastic material component that responds to stress with a flow, no matter the proportions of the first and second component. It may be understood that the above shear test does not apply to the second component alone.
In FIG. 1, an embodiment of a system 10 is shown that includes a first component or bone cement injector 100 may extend into the cancellous bone of a vertebra, and a second component or cement activation component 105 which includes an emitter 110 for applying energy to bone cement. The first and second components 100 and 105 may include a flow passageway or channel 112 extending therethrough for delivering flowable bone cement into a bone. The bone cement injector component 100 and the cement activation component 105 can be integrated into a unitary device or can be de-mateable, as shown in FIG. 2, by a mechanism such as a threaded portion 113 and a rotatable screw-on fitting 114. As can be seen in FIGS. 1 and 2, a source of bone cement in the form of a syringe-type body 115 is also coupleable to the system by use of a threaded fitting 116.
Referring to FIG. 2, the bone cement injector 100 may include a proximal end 118 and a distal end 120 with at least one flow outlet 122 therein to direct a flow of cement into a bone. The extension portion 124 of the injector 100 can be made of any suitable metal or plastic sleeve with flow channel 112 extending therethrough to the flow outlet 122. The flow outlet 122 may be present as a side port to direct cement flow transverse relative to the axis 125 of extension portion 124 or, alternatively, can be positioned at the distal termination of extension portion 124 in order to direct cement flows distally. In another embodiment (not shown) the extension portion 124 can include first and second concentric sleeves that are positioned so as to be rotated relative to one another to align or misalign respective first and second flow outlets to allow selectively directed cements flow to be more or less axial relative to axis 125 of extension portion 124.
Now turning to the cut-away view of FIG. 2, it can be seen that second component 105 includes a handle portion that carries an emitter 110 for applying thermal energy to a cement flow within the flow channel 112 that extends through the emitter 110. As will be described further below, the emitter 110 may apply thermal energy to bone cement 130 delivered from chamber 132 of source 115 to flow through the emitter 110 to therein to cause the viscosity of the cement to increase to a selected, higher viscosity value as the cement exits the injector flow outlet 122 into bone. The controlled application of energy to bone cement 130 may enable the physician to select a setting rate for the cement to reach a selected polymerization endpoint as the cement is being introduced into the vertebra, thus allowing a high viscosity that will be prevent unwanted cement extravasation.
Referring to FIGS. 2 and 3, in one embodiment, the thermal energy emitter 110 may be coupled to an electrical source 140 and controller 145 by an electrical connector 146 and a cable 148. In FIG. 2, it can be seen that electrical leads 149 a and 149 b may be coupled with connector 146 and extend to the emitter 110. As can be seen in FIG. 3, one embodiment of thermal energy emitter 110 has a wall portion 150 that includes a polymeric positive temperature coefficient of resistance (PTCR) material with spaced apart interlaced surface electrodes 155A and 155B as described in co-pending Provisional Application No. 60/907,469 filed Apr. 3, 2007 titled Bone Treatment Systems and Methods. In this embodiment, the thermal emitter 110 and wall 150 thereof may resistively heat to thereby cause controlled thermal effects in bone cement 130 flowing therethrough. It may be appreciated that FIG. 3 is a schematic representation of one embodiment of thermal energy emitter 110 which can have any elongated or truncated shape or geometry, tapered or non-tapered form, or include the wall of a collapsible thin-wall element. Further, the positive (+) and negative (−) polarity electrodes 155A and 155B can have any spaced apart arrangement, for example radially spaced apart, helically spaced apart, axially spaced apart or any combination thereof. This resistively heated PTCR material of the emitter 110 may further generate a signal that indicates flow rate as described in Provisional Application No. 60/907,469 which in turn can be utilized by controller 145 to modulate energy applied to the bone cement therein, and/or modulate the flow rate of cement 130, which can be driven by a motor or stored energy mechanism. In another embodiment, the emitter can be any non-PTCR resistive heater such as a resistive coil heater.
Referring FIG. 2, it can be understood that a pressure mechanism 190 is coupleable to the bone cement source or syringe 115 for driving the bone cement 130 through the system 10. The pressure 190 can include any suitable manual drive system or an automated drive system such as any pump, screw drive, pneumatic drive, hydraulic drive, cable drive or the like. Such automated drive systems may be coupled to controller 145 to modulate the flow rate of cement through the system.
In one embodiment, shown in FIGS. 4-6, the system 10 may further include a hydraulic system 162 with a fitting 163 that may detachably couple to fitting 164 of the bone cement source 115. In this embodiment, the bone cement source 115 may include a syringe body with cement-carrying bore or chamber 165 that carries a pre-polymerized, partially polymerized, or recently-mixed bone cement 130 therein. The hydraulic system 162 may further include a rigid plunger or actuator member 175 with o-ring or rubber head 176 that may move in chamber 165 so as to push the cement 130 through the syringe chamber 165 and the flow channel 112 in the system 100.
Still referring to FIGS. 4-6, a force application and amplification component 180 of the hydraulic system 162 may be reversibly couple to the bone cement source 115, where the force application and amplification component 180 includes a body 182 with pressurizable bore or chamber 185 therein that slidably receives the proximal end 186 of the actuator member 175. The proximal end 186 of actuator member 175 may include an o-ring or gasket 187 so that the bore 185 can be pressurized with flow media 188 by the pressure source 190 in order to drive the actuator member 170 distally to thereby displace bone cement 130 from the chamber 132 in the cement source or syringe 115. In one embodiment, illustrated in FIG. 5, the surface area of an interface 200 between the actuator member 175 and pressurized flow media 188 may be larger than the surface area of an interface 200′ between the actuator member 175 and the bone cement 130 so as to thereby provide pressure amplification between the pressurizable chamber 185 and chamber 132 of the cement source or syringe. In one embodiment, as indicated in FIGS. 4 and 5, the surface area of interface 200 may be at least about 150% of the surface area of interface 200′, at least about 200% of the surface area of interface 200′, at least about 250% of the surface area of interface 200′ and at least about 300% of the surface area of interface 200′.
Referring to FIGS. 4 and 5, in one embodiment, the force application and amplification component 188 may be employed in the following manner. In a first operation, a bone fill material injector with a displaceable, non-fluid actuator component intermediate a first fluid chamber and a second cement or fill-carrying chamber may be provided. In a second operation, a flow of flow media may be provided into the first fluid chamber at a first pressure to thereby displace the actuator component to impinge on and eject bone cement or fill at a higher second pressure from the second chamber into a vertebra. In a non-limiting example, a second pressure may be provided in the cement-carrying chamber 165 that is greater than the first pressure in the pressurizable chamber.
In one embodiment, the second pressure may be at least about 50% higher than the first pressure in the pressurizable chamber 185. In another embodiment, the second pressure may be at least about 75% higher that the first pressure in the pressurizable chamber 185. In another embodiment, the second pressure may be at least about 100% higher that the first pressure in the pressurizable chamber 185. In another embodiment, the second pressure may be at least about 200% higher that the first pressure in the pressurizable chamber 185. In another embodiment, the second pressure may be at least about 300% higher that the first pressure in the pressurizable chamber 185.
It may be appreciated that the pressurizing mechanism or pressure source 210 can include any type of mechanism or pump known in the art to actuate the actuator member 175 to move the bone cement in chamber 165. For example, a suitable mechanism can include a piezoelectric element for pumping fluid, an ultrasonic pump element, a compressed air system for creating pressure, a compressed gas cartridge for creating pressure, an electromagnetic pump for creating pressure, an air-hammer system for creating pressure, a mechanism for capturing forces from a phase change in a fluid media, a spring mechanism that may releaseably store energy, a spring mechanism and a ratchet, a fluid flow system and a valve, a screw pump, a peristaltic pump, a diaphragm pump, rotodynamic pumps, positive displacement pumps, and combinations thereof.
Referring to FIG. 6, another feature of embodiments of the present disclosure is a remote switch 212 for actuating the pressure mechanism 190. In one embodiment, a cable 214 extends from the controller 145 so that the physician can stand outside of the radiation field created by any imaging system used while treating a vertebra or other bone treatment site. In another embodiment, the switch 212 can be wirelessly connected to the system as is known in the art. In another embodiment (not shown), the elongated cable 214 and switch 212 can be directly coupled to the injector 100 or other component of the system 10.
Now turning to FIGS. 7, 8A and 8B, the figures illustrate certain embodiments of a method of the present disclosure where the controlled application of energy to a bone cement 130 provides a bone cement with a controlled, on-demand increased viscosity and a controlled set time compared to prior art bone cements. FIG. 7 depicts a prior art bone cement known in the art, such as a PMMA bone cement, that has a time-viscosity curve 240 where the cement substantially hardens or cures within about 8 to 10 minutes post-mixing. On the horizontal axis of FIGS. 7 and 8A, the time point zero indicates the time at which the mixing of bone cement precursors, such as monomer and polymer components, is approximately completed.
As can be seen in time-viscosity curve 240 for the prior art bone cement of FIG. 7, the cement increases in viscosity from about 500 Pa·s to about 750 Pa·s from time zero to about 6 minutes post-mixing. Thereafter, the viscosity of the prior art bone cement increases very rapidly over the time interval from about 6 minutes to 8 minutes post-mixing to a viscosity greater than 4000 Pa·s. A prior art bone cement having the time-viscosity curve of FIG. 7 may be considered to have a fairly high viscosity for injection in the range of about 500 Pa·s. At this viscosity range, however, the bone cement can still have flow characteristics that result in extravasation.
Still referring to FIG. 7, it can be understood that the curing reaction of the bone cement involves an exothermic chemical reaction that initiates a polymerization process that is dictated, at least in part, by the composition of the bone cement precursors, such as one or more of a PMMA polymer, monomer, and initiator. FIG. 7 indicates the exothermic curing reaction over time as a gradation, where, the lighter gradation region indicates a lesser degree of chemical reaction and heat and the darker gradation region indicates a greater degree of chemical reaction and heat leading to more rapid polymerization of the bone cement precursors.
Now turning FIG. 8A, the block diagram illustrates an embodiment of a method of utilizing applied energy and an energy-delivery algorithm to accelerate the polymerization of a PMMA bone cement to provide a selected time-viscosity curve as shown in FIG. 8B. In FIGS. 7 and 8B, it can be seen that the time-viscosity curve 250 of one embodiment of a bone cement can have an initial viscosity is in the range of about 750 Pa·s at about time zero post-mixing and thereafter the viscosity increases in a more linear manner over about 10 to 14 minutes post-mixing than prior art bone cements. This embodiment of bone cement may include a PMMA cement composition that provides a time-viscosity curve as in FIGS. 7 and 8B, as described in U.S. Provisional Application No. 60/899,487 filed on Feb. 5, 2007, titled Bone Treatment Systems and Methods, and U.S. application Ser. No. 12/024,969, filed on Feb. 5, 2008, titled Bone Treatment Systems and Methods, which are each incorporated herein by this reference in their entirety. As can be seen in FIG. 8B, the bone cement 130, or more particularly, the mixing of the cement precursors includes a first curing reaction source for curing the bone cement as described above and results in the predetermined exothermic curing reaction post-mixing that is indicated by the gradations of reaction under the time-viscosity curve 250.
Still referring to FIG. 8B, the chart illustrates the PMMA bone cement with time-viscosity curve 250 together with the modified time-viscosity curve 260. The modified time-viscosity curve may be provided by the application of energy employing an embodiment of the system 10 of the present disclosure, as depicted in FIGS. 1 and 4-6. In other words, FIG. 8B illustrates one embodiment of the present disclosure, where the bone cement 130 undergoes a curing process (i.e., the time-viscosity curve 250) owing to self-heating of the composition as components of the bone cement composition react with each other. This curing process may be further influenced by the applied energy from energy source 140, controller 145 and emitter 110 to provide the modified time-viscosity curve 260 for cement injection into a bone in order to prevent extravasation.
The bone cement 130 and system 10 of embodiments of the present disclosure are therefore notable in that a typical treatment of a vertebral compression fracture requires cement injection over a period of several minutes, for example from about 2 to 10 minutes or about 2 to 6 minutes, or about 2 to 4 minutes. The physician typically injects a small amount of bone cement, for example, about 1 of 2 cc's, then pauses cement injection for the purpose of imaging the injected cement to check for extravasation, then injecting additional cement and then imaging, etc. The steps of injection and imaging may be repeated from about 2 to 10 times or more, where the complete treatment interval can take about 4 to 6 minutes or more. It can be easily understood that a cement with a working time of at least about 5-6 minutes is needed for a typical treatment of a VCF, otherwise the first batch of cement may be too advanced in the curing process (see FIG. 7) and a second batch of cement may need to be mixed. In embodiments of the cement 130 and system 10 of the present disclosure, however, as indicated in FIG. 8B, the cement viscosity can be approximately constant, thus providing a very long working time of about 8-10 minutes.
In another embodiment of the present disclosure, referred to FIG. 9, the controller 145 may also allow the physician to select an energy-delivery algorithm in the controller 145 to increase and decrease the cement viscosity as the cement exits the injector following the application of energy to the cement flow. Beneficially, such algorithms may provide substantially automated control of the application of energy to the composition by the system 10.
Thus, in another embodiment, a bone treatment system 10 may be provided that employs algorithms for modulating energy applied to the bone cement system 130. The bone treatment system 130 may include a bone cement injector system, a thermal energy emitter 110 that may deliver energy to a flow of bone cement through the injector system, and a controller. The controller 145 may include hardware and/or software for implementing one or more algorithms for modulating applied energy from the emitter 110 to a bone cement flow. The energy-delivery algorithms may be further employed to increase the applied energy from about zero to a selected value at a rate that inhibits vaporization of at least a portion of a monomer portion of the bone cement 130.
In another embodiment of the present disclosure, the controller 145 may enable a physician to select a bone cement viscosity using a selector mechanism operatively connected to the controller 145. In certain embodiments, the selector mechanism may cause the controller 145 to initiate one or more of the energy-delivery algorithms. In one embodiment, the physician can select among a plurality of substantially constant viscosities that can be delivered over the working time. Examples of ranges of such viscosities may include less than about 1,000 Pa·s and greater than about 1,500 Pa·s. It should be appreciated that, in certain embodiments, from two to six or more such selections may be enabled by the controller 145, with each selection being a viscosity range useful for a particular purpose, such as about 1,000 Pa·s for treating more dense bone when extravasation is of a lesser concern, or between about 4,000 Pa·s and 6,000 Pa·s in a treatment of a vertebral fracture to prevent extravasation and to apply forces to vertebral endplates to reduce the fracture.
In order to facilitate energy application to the bone cement composition in a repeatable manner, the system 10 may further include a temperature sensor 272 that is disposed in a mixing device or assembly 275. The mixing assembly 275 may include any container that receives bone cement precursors for mixing before placement of the mixed cement in the bone cement source 115 (see FIG. 6). In certain embodiments, the temperature sensor 272 may be placed in the cement mixing assembly 275 because cement may be stored in a hospital in an environment having a lower or higher temperature than the operating room, which may affect the time-viscosity curve of the cement. The temperature sensor 272 can be operatively coupled to the controller 145 by a cable or a wireless transmitter system. In certain embodiments, the sensor 272 may be unitary with the mixing assembly 175 and disposable. In alternative embodiments, the sensor 272 can be reusable and detachable from the mixing assembly 275.
In another embodiment, still referring to FIG. 6, a temperature sensor 276 may be operatively connected to one or more packages 280 of the bone cement precursors to thereby indicate the actual temperature of the cement precursor(s) prior to mixing. Such a temperature sensor 276 may indicate the stored temperature and/or the length of time that such cement precursors have been in the operating room when compared to ambient room temperature measured by sensor 270 in the controller 145. This sensor 276 can include one or more temperature sensors that may include, but are not limited to, thermocouples, or thermochromic inks. The temperature sensors 276 may be further disposed on the surface of the bone cement package 280, allowing for visual identification of the temperature of the cement precursors. In this manner, a doctor or technician may read the temperature of the package 280 and manually input this temperature into the controller 145 to enable automatic adjustment of the energy delivery algorithms of embodiments of the controller 145. In another embodiment, referring back to FIG. 4, at least one temperature sensor 282 can be located in cement source 115 of the system and/or in a distal portion of the injector component 100 for monitoring cement temperature in a cement flow within the system 10.
Thus, in another embodiment, a bone treatment system may include a bone cement injector system 10 that includes a thermal energy emitter 110 that may deliver energy to a bone cement within the injector system, a controller 145 that may modulate applied energy from the emitter to control a curing reaction of the cement, and a sensor system operatively coupled to the injector system 100 for measuring an operational parameter of bone cement 130 within the system 10. In FIG. 6, in one embodiment, it can be seen that a sensor of the sensor system may include a temperature sensor, indicated at 270, which is disposed in controller assembly 145. The temperature sensor 270 of the controller assembly 145 may allow for input of control algorithms into the system 10 for modulating applied energy from the emitter 110 that are dependent on ambient air temperature in the operating room environment. Such control algorithms may be of significant utility, as the ambient temperature of an operating room may affect the time-viscosity curve of an exothermic PMMA-based bone cement.
In another embodiment, the bone cement system 10, and more particularly, the cement mixing assembly 275 of FIG. 6 may include a sensor, switch, or indication mechanism 285 for indicating an approximate time of initiation of bone cement mixing. Such a sensor or indication mechanism 285 can include any manually-actuated mechanism coupled to the controller 145, a mechanism that senses the disposition of the cement precursors in the mixing assembly or the actuation of any moveable mixing component of the assembly, and combinations thereof. The system 10 and controller 145 may, in this manner, provide one or more of visual, aural, and/or tactile signals indicating that a selected mixing time interval has been reached. This signal may enable consistent measurement of the time at which mixing of the bone cement is completed, also referred to as the zero post-mixing time, such that the viscosity at this time may be similar in all cases. Beneficially, by precise, consistent measurement of the zero post-mixing time, energy may be properly applied as described above. The system 10 also can include a sensor, switch or indication mechanism 288 that indicates the termination of bone cement mixing, and thus time zero on a time-viscosity curve as in FIG. 9, which may be used for setting the algorithms in the controller 145 for controlling applied energy and the cement flow rate.
In another embodiment, the bone cement system 10 may include a sensor that measures and indicates the bone cement flow rate within the flow passageway in the injector system 100. In the embodiment of FIG. 6, the motor drive system 211 may drive the cement via the hydraulic system 162 at a substantially constant rate through the injector and emitter 110. A sensor 290 may be operatively coupled to the motor drive which can measure the force being applied by the drive to the cause the desired cement flow through the system 10, which can in turn be used to sense any tendency for a slow-down in the desired flow rate, for example due to an unanticipated increase in viscosity of the bone cement in the system 10. Upon such sensing, the controller 145 can increase the flow rate or decrease the applied energy from emitter 110 to allow a selected cement viscosity and flow rate from the injector 100 into bone to be maintained.
Embodiments of such bone cements 130, in combination with the system 10 of the embodiments of the present disclosure, may thus allow for selected working times. Examples of such working times may include, but are not limited to, at least about 6 minutes, at least about 8 minutes, at least about 10 minutes, at least about 12 minutes, at least about 14 minutes, at least about 16 minutes, at least about 18 minutes, at least about 20 minutes, and at least about 25 minutes.
In one embodiment, the bone treatment system may include: a first and second energy source for causing a controlled curing reaction in a bone cement. The first source may include an exothermic curing reaction which occurs in response to mixing cement precursor components. The second source may include a thermal energy emitter capable of applying energy to the bone cement in order to vary an exothermic curing reaction of the bone cement. The system may further include a controller capable of modulating the applied energy from the emitter to thereby control the exothermic curing reaction over a selected working time. The controller may be capable of modulating applied energy to provide a selected bone cement viscosity over a working time of at least about 2 minutes, at least about 4 minutes, at least about 6 minutes, at least about 8 minutes, at least about 10 minutes, at least about 12 minutes, at least about 14 minutes, at least about 16 minutes, at least about 18 minutes, at least about 20 minutes, and at least about 25 minutes.
Thus, in another embodiment of the present disclosure, a method of preparing a curable bone cement for injection into a vertebra may be provided. The method can include: mixing bone cement precursors so as to enable a curing reaction to take place in the bone cement and applying energy to the bone cement from an external source so as to provide energy to the bone cement. The energy applied from the external source may be controlled by a controller in combination with the curing reaction so as to provide a selected cement viscosity.
Embodiments of the method may further include varying the amount of energy applied from the external source in response to a selected length of a post-mixing interval. Embodiments of the method may include varying the amount of applied energy from the external source in response to ambient temperature that is measured by a temperature sensor in the system.
Further, embodiments of the method may include varying the applied energy from the external source in response to a selected injection rate of the bone cement flow through the system 10. Embodiments of the method may include varying the applied energy from the external source so as to provide a bone cement having an injection viscosity of at least about 500 Pa·s, at least about 1000 Pa·s, at least about 1500 Pa·s, at least about 2000 Pa·s, at least about 3000 Pa·s and at least about 4000 Pa·s.
In further embodiments the control system may allows for application of energy to a bone cement so as to provide a bone cement that possesses a substantially constant cement viscosity over the selected working time.
In further embodiments the control system 10 may allow for the application of energy to a bone cement so as to provide a bone cement that possesses a plurality of selected time-viscosity profiles of the cement as it exits the injector 100. For example, the controller 145 and energy emitter 110 may be capable of applying energy to the bone cement in an amount that is sufficient to very rapidly increase the viscosity of the bone cement to a selected viscosity that will inhibit extravasation.
As can be seen in the time-viscosity curve 260 of FIG. 8B, embodiments of the system 10 and the bone cement 130 discussed herein may be employed to provide a bone cement whose viscosity can be elevated to above about 2000 Pa·s within about 15-30 seconds. It may be understood that embodiments of the method of bone cement treatment may include utilizing an energy emitter 110 that applies energy to bone cement to controllably increase its viscosity to at least 200 Pa·s, at least 500 Pa·s or at least 1,000 Pa·s in less than 2 minutes or less than 1 minute. Alternatively, embodiments a method of bone cement treatment may include utilizing an energy emitter that applies energy to bone cement to controllably increase the viscosity to at least 1,000 Pa·s, at least 1,500 Pa·s, at least 2,000 Pa·s or at least 2,500 Pa·s in less than 2 minutes or less than 1 minute.
In further embodiments, a method of preparing a curable bone cement for injection into a vertebra may be provided allows a bone cement to exhibit a selected time-viscosity profile. The method may include: mixing bone cement precursors so as to cause a curing reaction characterized by a first time-viscosity profile of the bone cement, actuating an energy controller so as to controllably apply energy to the bone cement from an external energy source so as to cause the bone cement to adopt a second time-viscosity profile, different from the first time-viscosity profile, and injecting the cement characterized by the cement second time-viscosity profile into the vertebra. In embodiments of this method, the cement viscosity may be at least about 500 Pa·s, at least about 1000 Pa·s, at least about 1500 Pa·s, at least about 2000 Pa·s, at least about 3000 Pa·s, or at least about 4000 Pa·s. Embodiments of the method may further include actuating the controller to modulate applied energy in response to control signals including, but not limited to, the length of a cement post-mixing interval, the ambient temperature, the bone cement temperature, and rate of bone cement injection into the vertebra.
FIG. 10 provides a schematic, graphical representation of the time-viscosity response, 250 and 255, respectively, of an embodiment of the bone cement of FIG. 8A after mixing at ambient temperatures of about 22° C. and 18° C. It can be seen that different levels of energy may be applied to achieve a similar time-viscosity curve 260 of FIG. 10. For example, less energy may be applied to bone cement at about 22° C. than is applied to the bone cement at about 18° C. in order to achieve the time-viscosity response 160, as the higher temperature bone cement, prior to energy application, contains more energy than lower temperature bone cement. Thus, in an embodiment, a method of the present disclosure may include providing inputs for the control algorithms for controlling applied energy to cement flows that factor in ambient temperatures.
As can be understood from FIGS. 1-6, the energy source 140 may also be capable of applying energy to the bone cement 130 via the emitter 110 and accelerating a polymerization rate of the bone cement 130 by at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90% and at least about 95%, as compared to the polymerization rate achieved absent this application of energy. In another embodiment of the present disclosure, the energy source 140 and controller 145 may be capable of accelerating the polymerization rate of the bone cement 130 to the selected endpoint in less than about 1 second, less than about 5 seconds, less than about 10 seconds, less than about 20 seconds, less than about 30 seconds, less than about 45 seconds, less than about 60 seconds and less than about 2 minutes.
An embodiment of a method of using the system 10 of FIGS. 1-6 to treat a vertebra is also provided. The method includes a first operation of introducing a cement injector needle into a vertebra. The needle may include a flow channel extending from a proximal injector end to a distal injector end possessing a flow outlet. The method may further include a second operation of causing a flow of bone cement from a bone cement source through a flow channel in an energy-delivery component and the injector needle. The method may additionally include applying energy from the energy-delivery component to the flow of bone cement so as to cause a change in the setting rate of the cement so as to reach a selected polymerization endpoint. In this method, the applied energy may accelerate setting of a bone cement before it exits the flow outlet of the injector. The method and the selected polymerization endpoint may further provide a bone cement that exhibits a viscosity that substantially prevents cement extravasation following introduction into the vertebra.
In an alternative embodiment, referring to FIG. 11, the bone cement system 400 may include a first and a second thermal energy emitter for controlled application of energy to a bone cement flow within the flow passageway 112 of the injector system 100. More particularly, first emitter 110 may be disposed in the first handle component 105 as described previously. A second emitter 410 may be disposed in a medial or distal portion of the second extension component 110 of the injector system 100. The controller 145 may be capable of modulating applied energy from the first and second emitters, 110 and 410, to provide a controlled curing reaction of the flow of bone cement 130. In one method of use, the first emitter 110 can apply energy to warm the flow of cement 130 to accelerate it polymerization so that the selected flow rate carries the cement 130 to the location of the second emitter 410 at a viscosity of less than about 500 to 1000 Pa·s and, thereafter, the applied energy of the second emitter 410 may increase the viscosity of the bone cement 130 to greater than about 2000 Pa·s. In this manner, the bone cement viscosity within the flow channel 112 can be kept at a level that can be pushed with a low level of pressure and the final viscosity of the cement 130 exiting the outlet 122 can be at a relatively high viscosity, for example, at a level capable of fracturing cancellous bone, such as greater than about 2000 Pa·s.
FIG. 11 further illustrates that electrical connector components 414 a and 414 b may be provided in the interface between the first and second components, 100 and 105, in order to provide an electrical connection from electrical source 140 to the emitter 410 via electrical wires indicated at 416 in the handle portion 105 of the system. It may be appreciated that the second emitter 410 can include a PTCR emitter, as described previously, or any other type of heating element. The heating element can have any length that includes the entire length of the extension portion 124. In one embodiment, the emitter 110 in handle component 105 has a length of less than about 50 mm and can carry a volume of cement that is less than about 1.0 cc, less than about 0.8 cc, less than about 0.6 cc, less than about 0.4 and less than about 0.2 cc.
In another embodiment of the method, the energy-delivery emitter 110 may be actuated by the operator from a location outside any imaging field. The cable carrying an actuation switch 212 can be any suitable length, for example about 10 to 15 feet in length (see FIG. 6).
In another embodiment of the method, the energy-delivery emitter 110 may be actuated to apply energy of at least about 0.01 Watt, at least about 0.05 Watt, at least about 0.10 Watt, at least about 0.50 Watt and at least about 1.0 Watt. In another embodiment of the method, the applied energy may be modulated by controller 145. In another embodiment of the method, the energy source 140 and controller 145 may be capable of accelerating the polymerization rate of the bone cement 130 to the selected endpoint in less than 1 second, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 45 seconds, 60 seconds and 2 minutes. In another embodiment of the method, the energy source 140 and controller 145 may be capable of applying energy to a bone cement composition 130 for accelerating the polymerization rate of the bone cement 130 by at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90% and at least about 95%, as compared to the polymerization rate absent the applied energy.
In certain embodiments, a method of bone cement injection is also provided. The method includes modulating a rate of bone cement flow in response to a determination of a selected parameter of the cement flow. Examples of the selected parameter may include the flow rate of the bone cement. The method of bone cement injection may further include applying thermal energy to the bone cement and modulating the thermal energy application from an emitter in the injector body to the cement flow. The method of bone cement injection may further include modulating the application of energy in response to signals that relate to a selected parameter, such as the flow rate of the cement flow.
In another embodiment, a method of bone cement injection is provided. The method includes (a) providing a bone cement injector body carrying a PTCR (positive temperature coefficient of resistance) material in a flow channel therein, (b) applying a selected level of energy to a bone cement flow traveling through the PTCR material, and (c) utilizing an algorithm that processes impedance values of the PTCR material in order to determine the bone cement flow rate. The method of bone cement injection may further include modulating a cement injection parameter in response to the processed impedance values. Examples of the cement injection parameter may include, but are not limited to flow rate, pressure, and power applied to the flow.
In a further embodiment, a method of bone cement injection is provided. The method may include: (a) providing a bone cement injector body carrying a PTCR material or other thermal energy emitter in a flow channel therein, (b) causing a bone cement to flow through the flow channel at a selected cement flow rate by application of a selected level of energy delivery to the cement flow through the emitter, and (c) modulating the selected flow rate and/or energy delivery to maintain a substantially constant impedance value of the emitter material over a cement injection interval. The selected cement injection interval can include at least about 1 minute, at least about 5 minutes, at least about 10 minutes, and at least about 15 minutes.
In another embodiment of the present disclosure, the method may modulate the selected flow rate and/or energy delivery to maintain a substantially constant viscosity of bone cement ejected from the injector over a selected cement injection time interval. The time interval may include from about 1 minute to 10 minutes. The system and energy source may be capable of applying energy of at least 0.01 Watt, 0.05 Watt, 0.10 Watt, 0.50 Watt and 1.0 Watt. In another embodiment, the energy source 140 and controller 145 may be capable of accelerating the polymerization rate of the bone cement to a selected endpoint in less than about 1 second, less than about 5 seconds, less than about 10 seconds, less than about 20 seconds, less than about 30 seconds, less than about 45 seconds, less than about 60 seconds and less than about 2 minutes.
Embodiments of the above-described method of bone cement injection may further provide a selected cement flow rate to provide a selected interval in which the cement flows are allowed to polymerize in the flow channel downstream from the energy emitter. This method may include providing a selected interval of greater than about 1 second, greater than about 5 seconds, greater than about 10 seconds, greater than about 20 seconds, and greater than about 60 seconds.
The above-described method may also utilize an energy emitter that applies energy sufficient to elevate the temperature of the bone cement 130 by at least about 1° C., at least about 2° C., and at least about 5° C. The method of bone cement injection may additionally include utilizing an energy emitter that applies at least about 0.1 Watts of energy to the cement flow, at least about 0.5 Watts of energy to the cement flow, and at least about 1.0 Watts of energy to the cement flow. The method may include adjustment of the flow rate of the bone cement flow in intervals by controller 145, or being continuously adjusted by a controller 145.
In another embodiment of a method of the present disclosure, the bone cement injection system of FIGS. 1-11 may utilize a controller 145 and algorithms for applying energy to bone cement flows to allow the bone cement 130 exiting the injector to possess a selected temperature that is higher than the ambient temperature of the injector. This ability reflects the fact that polymerization has been accelerated, thus reducing the amount of total heat released into bone. More particularly, the method may include injecting a settable bone cement into a bone after mixing a first component and a second component of the bone cement, thereby initiating a chemical reaction to initiate setting of the bone cement, accelerating the polymerization with applied energy from an external source, and ejecting the bone cement from an injector portion positioned in bone. The bone cement, upon ejection, may possess a temperature greater than the temperature ambient the injector. The method can further include ejecting the bone cement from a terminal portion of an injector positioned in bone at a temperature of at least about 28° C., at least about 30° C., at least about 32° C., at least about 34° C., at least about 36° C., at least about 38° C., at least about 40° C., at least about 42° C., at least about 44° C., at least about 46° C., at least about 48° C., at least about 50° C., at least about 52° C., at least about 54° C., at least about 56° C., at least about 58° C., at least about 60° C., at least about 62° C., at least about 64° C., at least about 66° C., at least about 68° C., at least about 70° C., at least about 72° C., at least about 74° C., at least about 76° C., at least about 78° C., and at least about 80° C.
In another embodiment, a method of injecting a bone cement into bone is provided. The method includes mixing first and second bone cement components, thereby causing an exothermic chemical reaction which results in a thermal energy release. The method may further include actuating an injector control system capable of controlling the temperature of the bone cement before the bone cement contacts bone. In general, the actuating step can include (i) controlling the flow rate of the bone cement within a flow passageway of an injector system, (ii) controlling the application of energy to the bone cement from an emitter operatively coupled to an energy source, and (iii) controlling the driving force applied to the flow of bone cement which may benefit from adjustment based on the bone cement viscosity.
In another embodiment, a method of injecting a bone cement is provided. The method includes mixing a first and a second bone cement components so as to cause an exothermic chemical reaction that results in a thermal energy release. The method also includes actuating an injector control system which is capable of controlling an amount of thermal energy released from the cement before the bone cement contacts bone tissue to thereby reduce the thermal energy released into the bone.
The thermal energy released from the cement may be directly related to the level of polymerization acceleration from the applied energy, as well as the dwell time of the cement within the flow channel before the cement exits the outlet in a terminal portion of the injector. The dwell time of the cement in the flow channel can be controlled by controller 145 as described above, where at least one of the flow rate and driving force applied to the cement flow can be modulated. In embodiments of the system 10 of FIGS. 1-6, the application of energy by emitter 110 in component 105 provides for a dwell time within the flow channel 112 before exiting outlet 122 for a flow interval of at least about 5 seconds, at least about 10 seconds, at least about 20 seconds, at least about 30 seconds, at least about 40 seconds and at least about 60 seconds. This method of conditioning and injecting bone cement can allow a thermal energy release from the bone cement before the bone cement contacts bone of at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45% and at least about 50% of the total thermal energy released during curing of the bone cement composition.
For example, in one embodiment, a method of injecting a bone cement controls the amount of thermal energy released by the bone cement before the bone cement contacts bone tissue. The method includes controlling an injector control system that is capable of controlling the rate of chemical reaction before the bone cement contacts bone tissue. The reaction rate can be adjusted by the controller such that the maximum composition temperature is reached when the cement is within the flow channel of the injector system, prior to reaching the bone tissue. Beneficially, in this manner, the amount of total thermal energy released by the bone cement is released while the bone cement is still within the flow channel of the injector system, before the bone cement contacts the bone tissue. This method substantially reduces the amount of thermal energy which is released by the bone cement into the bone tissue.
In another embodiment, a method of injecting bone cement includes an actuating step that can include allowing at least about 10% of the total thermal energy released from a bone cement to be released while the bone cement flows within the injector system. In certain embodiments, such energy release may be accomplished by providing a mean cement flow rate of at least about 0.1 cc/min, at least about 0.5 cc/min, at least about 1.0 cc/min, at least about 1.5 cc/min, at least about 2.0 cc/min and at least about 2.5 cc/min during heating within the bone cement injector. The method may further include maintaining the bone cement within the cannula for at least about 20 seconds after being heated.
In another embodiment of the method of injecting bone cement, the actuating step can allow at least about 10% of the total thermal energy released from a bone cement to flow over a flow distance within the flow channel 112 of the injector system, of least 5 mm, at least 10 mm, at least about 20 mm, at least about 30 mm, at least about 40 mm, at least about 50 mm, at least about 60 mm, at least about 70 mm, at least about 80 mm, at least about 90 mm and at least about 100 mm.
In certain embodiments of the methods described above to apply energy to a selected volume of a bone cement mixture, a selected amount of thermal energy from the exothermic reaction of the bone cement components may be released within the flow channel so as to inhibit a selected portion of the thermal energy from reaching a patient's bones. Beneficially, in this manner, a reduction in the thermal effects in the bone due to introduction of the bone cement within the bone may be achieved. Embodiments of the method can include selecting first and second bone cement components, or precursors, that result in a peak temperature of the bone cement composition during curing of less than about 75° C., less than about 70° C., less than about 65° C., and less than about 60° C. Embodiments of such bone cements may include those bone cements described herein.
Thus, from the above disclosure, it can be understood that, in an embodiment, a bone cement injection system of the present disclosure includes first and second bone cement components, or precursors, that, upon mixing, result in a chemical reaction that sets the cement mixture. The bone cement injection system further includes an injector system that may include a drive system for inducing the cement mixture to flow through the system and into bone. The bone cement injection system may further include an energy emitter for applying energy to the cement mixture in the injector system to thereby accelerate the chemical reaction between the first and second bone cement components therein. The bone cement injection system may also include a controller, operatively coupled to at least one of the drive system and energy emitter, for controlling the acceleration of the chemical reaction in the bone cement. In one embodiment, the first and second bone cement components, or precursors, may possess a post-mixing peak temperature of less than about 75° C., less than about 70° C., less than about 65° C. and less than about 60° C. The drive system and the controller may further be capable of controllably applying a driving force to the cement mixture in the injector system of at least about 500 psi, at least about 1,000 psi, at least about 1,500 psi, at least about 2,000 psi, at least about 2,500 psi, at least about 3,000 psi, at least about 3,500 psi, at least about 4,000 psi, at least about 4,500 psi and at least about 5,000 psi.
In one embodiment, the drive system and controller may be capable of controllably maintaining a substantially constant flow rate of the cement mixture. Examples of the flow rate control may include, but are not limited to, flow rate variations that are within less than about 1% variation; less than about 5% variation; less than about 10% variation and less than about 15% variation.
In one embodiment, the drive system and controller may be capable of controlling a mean cement mixture flow rate. The mean cement flow rate may include at least about 0.1 cc/min, at least about 0.5 cc/min, at least about 1.0 cc/min, at least about 1.5 cc/min, at least about 2.0 cc/min and at least about 2.5 cc/min.
The energy emitter and controller may further be capable of controllably applying energy to the cement mixture. In certain embodiments, controller may provide at least about 20 joules/cc, at least about 40 joules/cc, at least about 60 joules/cc, at least about 80 joules/cc, at least about 100 joules/cc, at least about 120 joules/cc, at least about 140 joules/cc, at least about 160 joules/cc, and at least about 180 joules/cc of the bone cement.
In a certain embodiment, the bone cement injection system may include an energy emitter and controller capable of providing a dynamic or a pre-programmed adjustment of applied energy to the cement mixture in response to a signal indicative of the flow rate of the cement mixture. The signal, in certain embodiments, may include a feedback signal to the controller 145 indicative of at least one of the temperature of the cement mixture, the viscosity of the cement mixture, the flow rate of the cement mixture and the driving force applied to the cement mixture, at least one environment condition, and combinations thereof.
Further embodiments of the present disclosure relate to bone cement compositions and formulations for use in the bone cement delivery systems described above, such as systems 10 and 400. The bone cement formulations may provide extended working times, since the viscosity of the bone cement can be altered and increased on demand when injected.
Bone cements, such as polymethyl methacrylate (PMMA), have been used in orthopedic procedures for several decades, with initial use in the field of anchoring endoprostheses in a bone. For example, skeletal joints such as in the hip are replaced with a prosthetic joint. About one million joint replacement operations are performed each year in the U.S. Frequently, the prosthetic joint may be cemented into the bone using an acrylic bone cement, such as PMMA. In recent years, bone cements also have been widely used in vertebroplasty procedures where the cement is injected into a fractured vertebra to stabilize the fracture and eliminate micromotion that causes pain.
In an embodiment, a polymethyl methacrylate bone cement may be provided. Prior to injection of the bone cement into a patient, the bone cement may include a powder component and a liquid monomer component. The powder component may include granules of methyl methacrylate or polymethyl methacrylate, an X-ray contrast agent and a radical initiator. Typically, barium sulfate or zirconium dioxide may be employed as an X-ray contrast agent. Benzoyl peroxide (BPO) may further be employed as radical initiator. The liquid monomer component may include a liquid methyl methacrylate (MMI), an activator, such as N,N-dimethyl-p-toluidine (DMPT), and a stabilizer, such as hydroquinone (HQ). Prior to injecting PMMA bone cements, the powder component and the monomer component are mixed and thereafter the bone cement hardens within several minutes following radical polymerization of the monomer.
Typical bone cements formulations, including PMMA formulations, used for vertebroplasty have a fairly rapid cement curing time after mixing of the powder and liquid components. This allows the physician to not waste time waiting for the cement to increase in viscosity prior to injection. Further, the higher viscosity cement is less prone to unwanted extravasation, which can cause serious complications. The disadvantage of such current formulations is that the working time of the cement, the time during which the cement is within a selected viscosity range that allows for reasonably low injection pressures while still being fairly viscous to help limit cement extravasation, is relatively short, for example, about 5 to 8 minutes. In one embodiment, the viscosity of the bone cement during the working time may range between approximately 50 to 500 N s/m2 and may be measured according to ASTM standard F451, “Standard Specification for Acrylic Bone Cement,” which is hereby incorporated by reference in its entirety.
In one embodiment, a bone cement of the present disclosure provides a formulation adapted for use with the cement injectors and energy delivery systems described above, such as systems 10 and 400. These formulations are distinct from conventional formulations and have greatly extended working times for use in vertebroplasty procedures with the viscosity control methods and apparatus disclosed herein and in co-pending applications listed and incorporated by reference above.
In one embodiment, the bone cement provides a formulation adapted for injection into a patient's body, where the setting time is about 25 minutes or more, more preferably about 30 minutes or more, more preferably about 35 minutes or more, and even more preferably about 40 minutes or more. Setting time is measured in accordance with ASTM standard F451.
In one embodiment, the bone cement of the present disclosure, prior to mixing and setting, includes a powder component and a liquid component. The powder component may include a PMMA that is about 64% to 75% by weight based on overall weight of the powder component. In this formulation, an X-ray contrast medium may be further provided in a concentration less than about 50 wt. %, such as about 25 to 35 wt. %, and about 27% to 32 wt. % based on overall weight of the powder component. The X-ray contrast medium, in one embodiment, may include barium sulfate (BaSO4) or zirconium dioxide (ZrO2). In one embodiment, the formulation may further include BPO that is about 0.4% to 0.8% by weight based on overall weight of the powder component. In another embodiment, the BPO is less than about 0.6 wt. %, less than about 0.4 wt. % and less than about 0.2 wt. % based on overall weight of the powder component. In such formulations, the liquid component may include MMA that is greater than about 99% by weight based on overall weight of the liquid component. In such formulations, the liquid component may also include DMPT that is less than about 1% by weight based on overall weight of the liquid component. In such formulations, the liquid component may also include hydroquinone that ranges between about 30 and 120 ppm of the liquid component. In such formulations, the liquid weight/powder weight ratio may be equal to or greater than about 0.4. In such formulations, the PMMA may includes particles having a mean diameter ranging from about 25 microns to 200 microns or ranging from about 50 microns to 100 microns.
In certain embodiments, the concentrations of benzoyl peroxide and DMPT within embodiments of the bone cement composition may be varied in order to adjust setting times. Studies examining the influence of bone cement concentration on setting times (FIG. 12) have demonstrated that, in bone cements comprising BPO and DMPT, increases in BPO and DMPT concentration increase the set time of the bone cement. The data further illustrate that, of the two bone cement constituents, BPO may exert a greater rate of effect on set time than does DMPT. Thus, in certain embodiments of the bone cement composition, the concentration of BPO, DMPT, and combinations thereof, may be increased within the ranges discussed above so as to increase the setting time of the composition.
The setting time of the cement may also be influenced by applying energy to the bone cement composition. As discussed above, embodiments of the injector system of FIGS. 1-11 may be capable of delivering energy to the bone cement composition. In certain embodiments, the applied energy may heat the bone cement composition to a selected temperature.
FIG. 13 illustrates temperature as a function of time from initial mixing for one embodiment of the bone composition so injected. The solid line of FIG. 13 represents the behavior of the bone cement composition when it is not heated by the injector system, referred to as condition 1. It is observed that, under condition 1, the composition exhibits three regimes. The first regime is low heating rate regime, where the temperature of the composition increases modestly with time. In this regime, the composition begins to slowly self-heat due the onset of a chemical reaction between at least a portion of its components. The second regime is a high heating rate regime, where the chemical reaction causes the composition temperature rises sharply. Once the temperature of the composition peaks, the composition enters a third, cooling regime, during which the temperature of the composition decreases back to room temperature.
Embodiments of the bone cement composition may further be heated using the injector system of FIGS. 1-11 in order to alter the viscosity of the composition. FIG. 14 illustrates measurements of viscosity as a function of time for an embodiment of the bone cement compositions heated to temperatures ranging between about 25° C. to 55° C. It may be observed that the bone cement at the lowest temperature, about 25° C., exhibits the slowest rate of viscosity increase, while the bone cement at the highest temperature, about 55° C., exhibits the highest rate of viscosity increase. Furthermore, at intermediate temperatures, the bone cement exhibits intermediate rates of viscosity increase.
In one embodiment, a bone cement has a first component comprising greater than about 99 wt. % methyl methacrylate (MMA), less than about 1 wt. % N,N-dimethyl-p-toluidine (DMPT), and about 30 to 120 ppm hydroquinone on the basis of the total amount of the first component, and a second component comprising a powder component comprising less than about 75 wt. % PMMA, less than about 50 wt. % of an X-ray contrast medium, and benzoyl peroxide (BPO).
In certain embodiments, the composition may further comprise less than about 0.4 wt. % (BPO) on the basis of the total weight of the second component. In further embodiments, the composition may comprise about 0.2 to 0.3 wt. % BPO on the basis of the total weight of the second component. In other embodiments, the second component has less than about 0.2 wt. % benzoyl peroxide (BPO) on the basis of the total weight of the second component, or less than about 0.1 wt. % benzoyl peroxide (BPO) on the basis of the total weight of the second component. In such a formulation, the liquid weight/powder weight ratio may be equal to or greater than about 0.4.
In one embodiment, the bone cement may include a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. The bone cement mixture, after mixing, may be characterized by having a viscosity of less than about 500 Pa·s at about 18 minutes post-mixing. The bone cement further can be characterized as having a time-viscosity curve slope of less than about 200 Pa·s/minute for at least about 5 minutes after reaching a viscosity of about 500 Pa·s. The bone cement further can be characterized by a post-mixing time-viscosity curve slope of less than 100 Pa·s/minute for at least about 15 minutes, at least about 16 minutes, at least about 17 minutes, at least about 18 minutes, at least about 19 minutes, and at least about 20 minutes.
In one embodiment, the bone cement includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. Post-mixing, the bone cement mixture may be characterized by a time-viscosity curve having a slope of less than about 100 Pa·s/minute until to the mixture reaches a viscosity of about 500 Pa·s. In other embodiments, the bone cement, post-mixing, can be characterized by a time-viscosity curve slope of less than about 100 Pa·s/minute immediately before the mixture reaches a viscosity of about 800 Pa·s. In this context, immediately may refer to a time period less than about 30 seconds. In other embodiments, the bone cement further can be characterized by a time-viscosity curve slope of less than about 100 Pa·s/minute immediately before the mixture reaches a viscosity of about 1000 Pa·s. In other embodiments, the bone cement further can be characterized by a time-viscosity curve slope of less than about 100 Pa·s/minute immediately before the mixture reaches a viscosity of about 1500 Pa·s.
In one embodiment, the bone cement may include a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, post-mixing, the mixture may be characterized by a time-viscosity curve having a rate of change of less than about 20% over an interval of at least about 5 minutes, at least about 10 minutes, at least about 15 minutes, and at least about 20 minutes. In other embodiments, the mixture may be characterized by a time-viscosity curve having a rate of change less than about 40% over an interval of at least about 5 minutes, at least about 10 minutes, at least about 15 minutes, and at least about 20 minutes.
In one embodiment, the bone cement may includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing, the mixture of the first and second components may be characterized as having a viscosity of less than about 100 Pa·s at about 10 minutes post-mixing, less than about 200 Pa·s at about 15 minutes post-mixing, or less than about 500 Pa·s at about 18 minutes post-mixing.
In another embodiment of the present disclosure, the bone cement formulation described above may include first and second cement precursors, such as the liquid and powder components discussed above. In certain embodiments, the cement mixture of the precursors may be characterized by a post-mixing interval in which viscosity is between about 500 Pa·s and 5000 Pa·s, and in which the change of viscosity of less than about 30%/minute. In another embodiment, the settable bone cement includes first and second cement precursors, where the cement mixture of the precursors is characterized by a post-mixing interval in which the viscosity of the mixture is between about 500 Pa·s and 2000 Pa·s, and in which the change of viscosity of the mixture is less than about 20%/minute.
In another embodiment, the cement includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing the first and second components, the mixture is characterized by a change of viscosity of less than 30%/minute for at least three minutes after reaching about 500 Pa·s, about 1000 Pa·s, about 1500 Pa·s, and about 2000 Pa·s.
In a related embodiment, the cement may includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing the first and second components, the mixture is characterized by a change of viscosity of less than about 40%/minute for at least about three minutes after reaching about 500 Pa·s, about 1000 Pa·s, about 1500 Pa·s, and about 2000 Pa·s.
In another embodiment, the cement includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing the first and second components, the mixture is characterized by a change of viscosity of less than 30%/minute for at least five minutes after reaching about 1000 Pa·s, about 1500 Pa·s, about 2000 Pa·s, about 2500 Pa·s, about 3000 Pa·s, about 3500 Pa·s, and about 4000 Pa·s.
In a further embodiment, the cement includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing the first and second components, the mixture is characterized by a change of viscosity of less than about 40%/minute for at least five minutes after reaching about 1000 Pa·s, about 1500 Pa·s, about 2000 Pa·s, about 2500 Pa·s, about 3000 Pa·s, about 3500 Pa·s, and about 4000 Pa·s.
In a related embodiment, the cement includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing the first and second components, the mixture is characterized by a change of viscosity of less than about 50%/minute for at least about five minutes after reaching about 1000 Pa·s, about 1500 Pa·s, about 2000 Pa·s, about 2500 Pa·s, about 3000 Pa·s, about 3500 Pa·s, and about 4000 Pa·s.
In another embodiment of the present disclosure, a cement includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing the first and second components, the mixture is characterized by a rate of change of viscosity of less than 50%/minute for an interval preceding the point in time the mixture achieves about 5000 Pa·s, the interval being at least about 2 minutes, at least about 3 minutes, at least about 4 minutes, at least about 5 minutes, at least about 6 minutes and at least about 8 minutes.
In a related embodiment, a cement includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing the first and second components, the mixture is characterized by a rate of change of viscosity of less than about 40%/minute for an interval preceding the point in time the mixture achieves about 5000 Pa·s, the interval being at least about 2 minutes, at least about 3 minutes, at least about 4 minutes, at least about 5 minutes, at least about 6 minutes, and at least about 8 minutes.
In a related embodiment, a cement includes a first monomer-carrying component and a second polymer-carrying component, such as the liquid and powder components discussed above. In certain embodiments, after mixing the first and second components, the mixture is characterized by a rate of change of viscosity of less than about 30%/minute for an interval preceding the point in time the mixture achieves about 5000 Pa·s, the interval being at least about 2 minutes, at least about 3 minutes, at least about 4 minutes, at least about 5 minutes, at least about 6 minutes, and at least about 8 minutes.
Now turning FIG. 15, embodiments of bone cement described above are characterized by their time-viscosity response, cements A and B, and compared with commercially available cements C, D and E. Cement A is a bone cement composition of the present disclosure having a PMMA to monomer ratio of about 2:1. Cement B is also a cement composition of the present disclosure having a PMMA to monomer ratio of about 2.5:1. Cement C is Mendec Spine bone cement which includes a PMMA to monomer ratio of about 2.1:1. D is DePuy Vertebroplastic cement which includes a PMMA to monomer ratio of about 2.3:1. Cement E is Arthrocare Parallax acrylic resin, which includes a PMMA to monomer ratio of about 2.4:1.
Embodiments of cement may be used with the system of FIGS. 1-11 or may be used in a conventional form of vertebroplasty. Further embodiments of the cement may be employed with the system of FIGS. 1-11 in order to provide any of the physical properties of the cement discussed herein.
In one embodiment, a settable bone cement may include a mixable first and second components, wherein the first component includes greater than about 99 wt. % methyl methacrylate (MMA), and less than about 1 wt. % N,N-dimethyl-p-toluidine (DMPT), about 30 to 120 ppm hydroquinone on the basis of the total amount of the first component, and wherein the second component includes a PMMA component that includes less than about 75 wt. % PMMA, less than about 32 wt. % of an X-ray contrast medium; and a selected wt. % of benzoyl peroxide (BPO) on the basis of the total weight of the second component. More particularly, the PMMA component may includes first and second volumes of polymer beads having first and second amounts of BPO, respectively.
In another embodiment, the bone cement may comprise a plurality of different PMMA beads of differing sizes, each carrying a BPO. The amount of BPO may be varied, as necessary, between the different PMMA beads. In another embodiment, the mean BPO amount contained within the plurality of beads may range from about 0.3 to 0.6 wt. on the basis of the total weight of the PMMA.
In another embodiment of bone cement, FIG. 18, the BPO configuration in the non-liquid component can include polymer particles 710 comprising layers of BPO. The BPO may be configured as a surface layer 714A which is present on at least a portion of an exterior surface of the polymer particles 710. In a further embodiment, one or more BPO layers 714B may be present within the interior of the polymer particles 710. In an additional embodiment, one or more surface BPO layers 714A may be present upon at least a portion of the surface of the exterior surface of the polymer particles 710 and one or more interior BPO layers 714B may be present within the interior of the polymer particles 710. The interior BPO layers 714B may be positioned at radial distances of about 5 to 80 μm from the center of the polymer particles 710. The BPO surface layers and interior layers 714A, 714B may possess thicknesses ranging between about 0.5 to 30 μm. In alternative embodiments, the volume of BPO surface coatings and interior layers 714A, 714B may range between about 1×10−1 to 1×10−4 cm3.
In another embodiment of a method of the present disclosure, a method of making a bone cement composition is provided. The method includes providing a liquid monomer component and polymer component, the polymer component having polymer particles contained therein. The method further includes distributing BPO within the polymer particles so as to provide a selected BPO availability (e.g., controlled exposure) to the liquid monomer component over at least first and second time intervals. In certain embodiments, the BPO may be selectively exposed to the liquid monomer over the at least first and second time intervals. In certain embodiments, the BPO availability per second over the first time interval is substantially greater than the BPO availability per second over the second time interval. In an embodiment, the first time interval may be at least about 1 minute, at least about 2 minutes, and at least about 3 minutes. The first time interval can be less than about 5 minutes. In other embodiments, the second time interval may be at least about 5 minutes, at least about 10 minutes, at least about 15 minutes, at least about 20 minutes, at least about 25 minutes, at least about 30 minutes, at least about 35 minutes, and at least about 40 minutes.
It can be understood that upon exposure to the liquid component in mixing, the monomer is initially exposed to the milled BPO surface 822, wetting the surface and thus providing the high BPO availability indicated by the first interval 815A of FIG. 22. Thereafter, the BPO availability would drop to zero as indicated in second interval 815B of FIG. 22. During this interval, the monomer would slowly dissolve the layer of PMMA material 824. At a selected subsequent point in time, depending on the selected thickness of the PMMA layer 824, the monomer would reach the BPO layer 822′ and thus BPO availability would increase as shown in third interval 815C of FIG. 22. The packed together particles 820 can separate and all BPO surface areas of these particles may then be exposed to the monomer. A bone cement composition that results from mixing liquid and non-liquid components as described above would then provide a cement composition having a time-viscosity curve 840 as shown in FIG. 25, which is superimposed over the BPO availability curve of FIG. 23.
In one specific formulation of a PMMA bone cement, the solid or powder component of the bone cement may include: PMMA, BPO, and ZrO2. In one embodiment, polymethylmethacrylate polymer (PMMA) is present within the bone cement in a concentration ranging between about 45%-55 wt. % on the basis of the total weight of the powder component. In other embodiments, the concentration of PMMA is about 49.6 wt. %. In other embodiments, the Benzoyl Peroxide (BPO) is present in a concentration ranging between about 0.30-0.80% on the basis of the total weight of the powder component In other embodiments, the concentration of BPO is about 0.40 wt. %. In additional embodiments, the concentration of Zirconium Dioxide or Barium Sulfate may range between about 45%-55% on the basis of the total weight of the powder component. In another embodiment, the concentration of Zirconium Dioxide or Barium Sulfate is less than or equal to about 50.0 wt.
In this cement formulation, the liquid component of the bone cement includes Methylmethacrylate (MMA), N,N-dimethyl-p-toluidine (DMPT), and Hydroquinone (HQ). In one embodiment, the concentration of Methylmethacrylate (MMA) may range between about 98.0-99.9 wt. % on the basis of the total weight of the liquid component. In other embodiments, the concentration of MMA may be about 99.5%. In other embodiments, the concentration of DMPT may range between about 0.15-0.95 wt. % on the basis of the total weight of the liquid component. In other embodiments, the concentration of DMPT may be about 0.50%. In other embodiments, the concentration of HQ may range between about 30-150 ppm on the basis of the total amount of the liquid component. In other embodiments, the concentration of HQ may be about 75 ppm
US3629187 * 25 Jun 1969 21 Dic 1971 Dentsply Int Inc Dental compositions containing adduct of 2 2' - propane bis 3-(4-phenoxy)-1 2-hydroxy propane - 1 - methacrylate and isocyanate
US4291608 26 Dic 1978 29 Sep 1981 Hilti Aktiengesellschaft Expansion dowel
US6872403 31 Ene 2001 29 Mar 2005 University Of Kentucky Research Foundation Polymethylmethacrylate augmented with carbon nanotubes
US7186267 8 Jun 2001 6 Mar 2007 Psimedica Limited Porous and/or polycrystalline silicon orthopaedic implant
US7191285 23 Mar 2004 13 Mar 2007 International Business Machines Corporation Configuring memory for a RAID storage system
US7252672 9 Mar 2004 7 Ago 2007 Skeletal Kinetics, Llc Use of vibration with orthopedic cements
US7259210 28 Ene 2002 21 Ago 2007 The Uab Research Foundation Bone cement and a system for mixing and delivery thereof
US7431763 11 Sep 2006 7 Oct 2008 Kyphon Sarl Magnesium ammonium phosphate cement composition
US20020165582 25 Abr 2002 7 Nov 2002 Porter Christopher H. Method and apparatus for delivering materials to the body
US20020183851 19 Mar 2002 5 Dic 2002 Cambridge Polymer Group, Inc. System and methods for reducing interfacial porosity in cements
US20070185231 23 Ene 2007 9 Ago 2007 Liu Y K Bone cement composite containing particles in a non-uniform spatial distribution and devices for implementation
US20080188858 1 Feb 2008 7 Ago 2008 Robert Luzzi Bone treatment systems and methods
US20100016467 27 Feb 2009 21 Ene 2010 Dfine, Inc. Bone treatment systems and methods
US20100280520 24 May 2010 4 Nov 2010 Dfine, Inc. Bone treatment systems and methods
US20110054482 9 Nov 2010 3 Mar 2011 Dfine, Inc. Composites and methods for treating bone
EP0361408A2 26 Sep 1989 4 Abr 1990 Wolff &amp; Kaaber A/S Improved bone cement
EP0361408A3 26 Sep 1989 2 May 1991 Jensen, Jorgen Steen Improved bone cement
EP0701824A2 7 Sep 1995 20 Mar 1996 MERCK PATENT GmbH Method of preparing osseous cements containing active agents
EP0701824A3 7 Sep 1995 18 Jun 1997 Merck Patent Gmbh Method of preparing osseous cements containing active agents
EP1366774A1 25 Abr 2003 3 Dic 2003 Heraeus Kulzer GmbH &amp; Co.KG Bone cement and X-ray contrast agent and methods of manufacturing the same
EP2397109B1 6 Dic 2005 10 Jun 2015 Dfine Inc. Bone treatment systems and methods
WO2004071543A Título no disponible
1 B. Heublein, R. Rohde, V. Kaese, M. Niemeyer, W. Hartung, A. Haverich, "Biocorrosion of magnesium alloys: a new principle in cardiovascular implant technology?", Heart, 2003: 89:651-656.
3 EPO Examination Report in EP Application No. 09 715 413.2, dated Aug. 18, 2011.
4 EPO Examination Report in EP Application No. 09 715 413.2, dated Mar. 25, 2011.
5 Exam Report for EPO App. 05 848 386.8 dated Sep. 18, 2009 in 5 pgs.
6 Furderer S, Anders M, Schwindling B, Salick M, Duber C, Wenda K, Urban R, Gluck M, Eysel P., "Vertebral body stenting. A method for repositioning and augmenting vertebral compression fractures", Orthopade, Apr. 2002; 31(4):356-61, Abstract.
7 International Preliminary Report on Patentability Written Opinion mailed on Aug. 31, 2010 in PCT Application No. PCT/US2009/03559.
8 International Search Report and written opinion mailed on Apr. 22, 2010 in PCT Application No. PCT/US2009/035549.
9 International Search Report and Written Opinion, mailing date Jun. 17, 2009, PCT/US2008/052821.
10 International Search Report, mailing date Apr. 16, 2007, PCT/US2006/034409.
11 International Search Report, mailing date Jun. 20, 2006, PCT/US2005/043984, 2 pg.
12 International Search Report, mailing date May 31, 2006, PCT/US2005/044055, 4 pg.
13 Japanese Office Action, re Application No. JP 2007-544613, dated Mar. 29, 2011 in 8 pages, with complete English translation.
14 Office Action in U.S. Appl. No. 11/148,973, mailed Apr. 16, 2009.
15 Office Action in U.S. Appl. No. 11/148,973, mailed Aug. 12, 2010.
16 Office Action in U.S. Appl. No. 11/148,973, mailed Feb. 28, 2008.
17 Office Action in U.S. Appl. No. 11/148,973, mailed Jun. 29, 2007.
18 Office Action in U.S. Appl. No. 11/148,973, mailed Nov. 27, 2009.
19 Office Action in U.S. Appl. No. 11/148,973, mailed Sep. 26, 2008.
20 Office Action in U.S. Appl. No. 11/165,045, mailed Mar. 26, 2008.
21 Office Action in U.S. Appl. No. 11/165,651, mailed Mar. 24, 2008.
22 Office Action in U.S. Appl. No. 11/165,651, mailed Sep. 21, 2007.
23 Office Action in U.S. Appl. No. 11/165,651, mailed Sep. 22, 2008.
24 Office Action in U.S. Appl. No. 11/165,652, mailed Mar. 20, 2008.
25 Office Action in U.S. Appl. No. 11/165,652, mailed Oct. 3, 2007.
26 Office Action in U.S. Appl. No. 11/165,652, mailed Sep. 19, 2008.
27 Office Action in U.S. Appl. No. 11/196,045, mailed Apr. 3, 2009.
28 Office Action in U.S. Appl. No. 11/196,045, mailed Jan. 7, 2010.
29 Office Action in U.S. Appl. No. 11/196,045, mailed Oct. 3, 2008.
30 Office Action in U.S. Appl. No. 11/196,089, mailed Aug. 17, 2010.
31 Office Action in U.S. Appl. No. 11/196,089, mailed Dec. 28, 2009.
32 Office Action in U.S. Appl. No. 11/196,089, mailed Jan. 3, 2008.
33 Office Action in U.S. Appl. No. 11/196,089, mailed May 8, 2009.
34 Office Action in U.S. Appl. No. 11/196,089, mailed Sep. 19, 2008.
35 Office Action in U.S. Appl. No. 11/208,448, mailed Apr. 3, 2009.
36 Office Action in U.S. Appl. No. 11/208,448, mailed Dec. 29, 2009.
37 Office Action in U.S. Appl. No. 11/208,448, mailed Nov. 30, 2007.
38 Office Action in U.S. Appl. No. 11/208,448, mailed Sep. 8, 2008.
39 Office Action in U.S. Appl. No. 11/209,035, mailed Jan. 3, 2008.
40 Office Action in U.S. Appl. No. 11/209,035, mailed May 20, 2009.
41 Office Action in U.S. Appl. No. 11/209,035, mailed Sep. 18, 2008.
42 Office Action in U.S. Appl. No. 11/469,769, mailed Dec. 11, 2008.
43 Office Action in U.S. Appl. No. 11/469,769, mailed Oct. 2, 2009.
44 Office Action in U.S. Appl. No. 11/767,402 mailed Aug. 10, 2009.
US9216195 * 19 Jun 2013 22 Dic 2015 Dfine, Inc. Bone treatment systems and methods
US20140031450 * 19 Jun 2013 30 Ene 2014 Dfine, Inc. Bone treatment systems and methods
Clasificación de EE.UU. 523/211, 525/265, 523/116
Clasificación internacional A61F2/28, C08K9/12, A61L24/06
Clasificación cooperativa A61B17/8833, A61L24/0094, A61K31/78, A61L2400/06, A61L27/46, A61L24/06, A61L24/0089, A61L24/0084, A61L24/001, A61B2017/00022, A61B17/8836, A61B17/8822, A61B17/7095, A61L2430/02, A61L27/50
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