US 20060182780 A1
A method of manufacturing a resorbable balloon designed to contain bone cement for vertebroplasty or kyphoplasty applications is described. The resorbable balloon can be inserted into a vertebral body following vertebral cavitation and filled with bone cement. The balloon remains in place in the vertebral body and resorbs over time. Methods and apparatus are also described for delivering therapeutic agents using collapsible, resorbable balloons. The balloons may be nested and filled with various therapeutic agents that are released over time at rates dependent upon structures and degradation rates of the balloons. Furthermore, the function of the hollow devices can encompass both encapsulation and therapeutic substance delivery roles simultaneously.
1. A method of forming a resorbable balloon, comprising:
heating a region of a tube and pulling tubing along an axis of the tube, thereby thinning a wall of the tube at the heated region;
forcing a gas or liquid through a lumen of the tube while heating the region of the tube, thereby causing a portion of the tubing to expand and form a balloon; and
sealing an end of the tube in proximity to the balloon.
2. The method as set forth in
extruding resorbable tubing; and
cutting tubing to desired lengths, thereby forming the plurality of tubes.
3. The method as set forth in
4. The method as set forth in
5. The method as set forth in
6. The method as set forth in
7. The method as set forth in
8. A resorbable balloon formed by the method of
9. A method of performing bone restoration, comprising:
providing a cavity within the bone;
inserting a deflated resorbable balloon into the cavity; and
filling the resorbable balloon with bone cement, thereby causing the resorbable balloon to expand and fill the cavity.
10. The method as set forth in
11. The method as set forth in
12. A method of providing therapy, comprising:
providing a first collapsible resorbable hollow device;
identifying a cavity in an anatomical location; and
inserting the first collapsible resorbable hollow device into the cavity.
13. The method as set forth in
14. The method as set forth in
the identifying of a cavity in an anatomical location comprises forming a cavity in a desired anatomical location; and
the inserting is preceded by deflating the hollow device; and
15. The method as set forth in
16. The method as set forth in
providing a second collapsible resorbable hollow device;
inserting the second collapsible resorbable hollow device into the first collapsible resorbable hollow device; and
injecting at least one therapeutic agent into the second collapsible resorbable hollow device.
17. The method as set forth in
providing one or more collapsible resorbable hollow devices;
nesting the collapsible resorbable hollow devices; and
injecting at least one therapeutic agent into each of the collapsible resorbable hollow devices.
18. The method as set forth in
19. The method as set forth in
20. The method as set forth in
21. The method as set forth in
22. The method as set forth in
23. The method as set forth in
24. The method as set forth in
25. The method as set forth in
26. The method as set forth in
27. The method as set forth in
28. The method as set forth in
29. The method as set forth in
30. The method as set forth in
31. The method as set forth in
32. The method as set forth in
removing the conduit; and
closing the opening.
33. The method as set forth in
34. A collapsible, resorbable balloon formed of one or more of aliphatic polyesters, polycarbonates, polyoxaesters, polyorthoesters, polyanhydrides, polyphosphoesters, polyphosphazenes, polypropylene fumarates, polyamino acids, other polyamides, pseudopoly(amino acids), polyamidoesters, polyarylates, polyoxaesters containing amine groups, polyalkylene oxalate, polyhydroxybuyrate, polyhydroxyvalerate, resorbable polyurethanes, resorbable starches, resorbable silk, and combinations (co- or multi-polymers or blend) of any of the above with nonresorbable polymers, and any combination thereof.
35. The collapsible, resorbable balloon as set forth in
36. The collapsible, resorbable balloon as set forth in
37. The collapsible, resorbable balloon as set forth in
This application claims the benefit of U.S. Provisional Application No. 60/653,778, filed Feb. 16, 2005 and entitled RESORBABLE BALLOON FOR BIOMEDICAL IMPLANTATION, and U.S. Provisional Application No. 60/672,839, filed Apr. 18, 2005 and entitled RESORBABLE HOLLOW DEVICES FOR DELIVERY OF THERAPEUTIC AGENTS, the entire contents of both which are hereby incorporated by reference. This application also relates to U.S. application Ser. No. 10/129,214 (Docket MA9263P), filed Oct. 21, 2002 and entitled TIME-RELEASED SUBSTANCE DELIVERY DEVICE, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to implants and, more particularly, to biomedical balloons and applications employing such balloons.
2. Description of Related Art
Balloon catheters have been employed in angioplasty applications for many years. A catheter having an inflatable balloon formed therein may be inserted into an artery percutaneously, and the balloon guided to a treatment area. The balloon may then be inflated in order to mitigate the effect of plaque deposits in, for example, a coronary artery. In some cases a balloon catheter is employed to implant a stent into an artery of a patient in order to decrease the likelihood of a recurrence of arterial blockage. Balloon catheters used in angioplasty are commonly removed from the patient after use as a result of, for example, typically being meant only to temporarily inflate the vessel or temporarily block the vessel for delivery of a stent or drugs. Additionally, removal of the balloon is typically necessary in order to attenuate complications that may arise pertaining, for example, to long-term effects which may stem from contact between a material of the balloon and the patient's tissue.
Balloon devices have found utility in biomedical areas other than cardiovascular applications. For example, balloons may be used in kyphoplasty applications wherein the effect of a vertebral fracture from osteoporosis is treated by inserting a balloon into a cavity formed in the fracture. Inflating the balloon may cause pieces of the fracture to return to a positions or orientations approximating those existing before for example a traumatic event that caused the fracture. Bone cement may then be inserted into the cavity in order to stabilize the bone fragments. In other vertebroplasty applications, bone cement may be inserted into, for example, cavities formed in weakened or fractured bones in order to provide enhanced strength and stability.
Unfortunately, cement extravasation can be a problem in these kyphoplasty and vertebroplasty situations. For instance, cement inserted into bone may extrude into surrounding tissues and nerves, causing pain and other complications. One way to prevent cement extravasation is to insert a balloon into the treatment cavity, fill the balloon with bone cement, and allow the cement to harden inside the balloon while the balloon remains in the body of the patient. Such a solution may not always be viable due for example to confounding factors such as situations wherein the presence of the balloon may prevent bonding between the bone cement and the bone tissue of interest. Consequently, gaps may form between an outer surface of the balloon and surrounding bone, introducing for example attendant risks of infection, bone loss, and pain.
A need thus exists in the prior art for a method of preventing cement extravasation in vertebroplasty and kyphoplasty applications. A further need exists for enabling bonding between bone cement and bone tissue following vertebroplasty and kyphoplasty treatments.
A medicinal substance can be administered to a patient systemically or locally. A systemically administered medicinal substance enters into the blood stream, travels throughout the body, and, preferentially, reaches the part of the patient's body in need of treatment at an effective dose before being degraded by metabolism and excreted. The systemic administration of medicinal substances can be achieved by oral application (e.g., syrups, tablets, capsules and the like), needle injection, transdermal delivery (e.g., a medicinal substance incorporated into a skin patch), and subdermal delivery (e.g., a medicinal substance formulation in a metabolizable matrix placed beneath the skin to release, for example, nicotine or birth control drugs). Systemically delivered medicinal substances can be inefficient when only a small amount of the administered dose reaches the site sought for therapeutic action. Moreover, with systemic delivery a medicinal substance can enter parts of the body where it can actually do harm or produce a noxious side effect.
Medicinal substances can be delivered locally by injection (e.g., injection of anesthetic into a patient's gums) or topically (e.g., creams, ointments, and sprays). Although the local delivery of medicinal substances can in some instances overcome problems of dilution and migration associated with systemic administration, multiple injections may be required to achieve or sustain a therapeutically effective dose over time. To avoid a need for multiple injections, a therapeutic agent may be delivered locally by way of a timed-released or controlled delivery type device. In many cases, timed-released devices are formed as a mixture or dispersion of the therapeutic agent in a degrading or non-degrading delivery material or vehicle. In some cases the therapeutic agent is destroyed, denatured, or looses its activity when combined with the delivery vehicle or material. In other cases, controlled delivery devices rely on diffusion of the therapeutic agent from the delivery material or vehicle, but the therapeutic agent may be too large to diffuse through a delivery material matrix of the controlled delivery device at a reasonable rate. In cases where the volume of the therapeutic time-released agent is large, an open procedure may be required to insert a relatively large therapeutic time-release device to the desired anatomical location. To avoid an open procedure for the delivery of a large volume of therapeutic agent, many small devices may be inserted, such as microspheres. The microspheres, however, may be difficult to retrieve if there is a complication. Even when local delivery of medicinal substances to a target site is possible, an important consideration still remains of maximizing the therapeutic effectiveness of the local drug delivery by controlling the proper dose and duration of the local delivery of the medicinal substance.
A need thus exists in the prior art for a delivery method or apparatus that can avoid undesirable activity losses of a therapeutic agent that may be associated with techniques that combine the therapeutic agent with a delivery material or vehicle. A further need exists for a method or apparatus that can avoid a requirement of diffusion of a therapeutic agent through a material of a delivery device. A still further need exists for methods or apparatus that may not require implantation of multitudes of small delivery devices and/or associated problems that may be presented of having to retrieve those small devices from an anatomical location upon the occurrence of complications, as well as methods or apparatus that may not require open surgical procedures for delivering large amounts of therapeutic agents.
The present invention provides a resorbable (e.g., bioresorbable, degradable, biodegradable, absorbable, bioabsorbable, erodible, bioerodible) balloon that can encapsulate cement in vertebroplasty and kyphoplasty applications until the cement has an opportunity to harden, thereby preventing incursion of the cement into soft tissue and nerves in a vicinity of bone being treated. The invention herein disclosed includes a method of forming a resorbable balloon comprising, according to an illustrative implementation, extruding resorbable tubing and cutting the tubing to desired lengths, thereby forming a plurality of tubes. A region of a tube is heated, and the tubing that forms the tube can be pulled along an axis of the tube, thereby thinning a wall of the tube at the heated region. Heated air is forced through a lumen of the tube while heating the region of the tube so that the tubing expands and forms a balloon in the heated region. An end of the tube is sealed by a thermal method or by gluing a resorbable plug into the lumen, and excess tubing beyond the sealed point is removed. According to an illustrative example, the resorbable balloon may be employed in a bone restoration procedure whereby a volume of bone is evacuated to form a cavity in the bone. A deflated resorbable balloon is inserted into the cavity, and the resorbable balloon is filled with bone cement, thereby inflating the balloon and filling the cavity. The resorbable balloon subsequently biodegrades to bring the bone cement into contact with bone within the cavity.
The present invention further provides apparatus and methods that may avoid problems associated with prior art methods of delivering therapeutic agents. Delivery methods and devices of various embodiments of the present invention may provide delivery of therapeutic agents while avoiding or attenuating problems associated with one or more of: combinations of the therapeutic agent with a delivery material or vehicle, diffusion through a material of the delivery device, implantation of multitudes of small delivery devices, and open surgical procedures. The invention herein disclosed thus can employ resorbable hollow devices which can be introduced into a desired anatomical location with, in many instances, a minimum of trauma. As an example, an implementation of a method according to the present invention can comprise a first collapsible resorbable hollow device, such as a resorbable balloon. A surgical procedure, which may be a laparoscopic procedure, may be performed to generate a cavity in a desired anatomical location of a body of a patient. The resorbable hollow device may be deflated, and subsequently inserted into the cavity. At least one therapeutic agent may be injected into the first collapsible resorbable hollow device. According to another implementation of the method, a second collapsible resorbable hollow device may be provided, and the second device may be inserted into the first collapsible resorbable hollow device. At least one therapeutic agent then may be injected into the second collapsible resorbable hollow device. Various therapeutic agents may be injected according to typical implementations of the present invention. For example, a therapeutic agent may comprise one or more of a natural organic substance, a synthetic organic substance, an inorganic substance, and combinations thereof.
Furthermore, the function of the hollow devices can encompass both encapsulation and therapeutic substance delivery roles simultaneously. An embodiment of the present invention may further comprise a collapsible resorbable balloon formed of resorbable material such as, for example, aliphatic polyesters, polycarbonates, polyoxaesters, polyorthoesters, polyanhydrides, polyphosphoesters, polyphosphazenes, polypropylene fumarates, polyamino acids, other polyamides, pseudopoly(amino acids), polyamidoesters, polyarylates, polyoxaesters containing amine groups, polyalkylene oxalate, polyhydroxybuyrate, polyhydroxyvalerate, resorbable polyurethanes, resorbable starches, resorbable silk, chitan or chitosan, and combinations (co- or multi-polymers or blends) of any of the above with or without, for example, nonresorbable polymers and/or natural substances.
While the apparatus and methods of the present invention have or may be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 U.S.C. 112, are not to be construed as necessarily limited in any way by the construction of “means” or “steps” limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 U.S.C. 112 are to be accorded full statutory equivalents under 35 U.S.C. 112.
Any feature or combination of features described herein are included within the scope of the present invention provided that the features included in any such combination are not mutually inconsistent as will be apparent from the context, this specification, and the knowledge of one skilled in the art. For purposes of summarizing the present invention, certain aspects, advantages and novel features of the present invention are described herein. Of course, it is to be understood that not necessarily all such aspects, advantages or features will be embodied in any particular embodiment of the present invention. Additional advantages and aspects of the present invention will be apparent in the following detailed description and claims that follow.
Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same or similar reference numbers may be used in the drawings and the description to refer to the same or like parts. It should be noted that the drawings are in simplified form and are not to precise scale. In reference to the disclosure herein, for purposes of convenience and clarity only, directional terms, such as, top, bottom, left, right, up, down, over, above, below, beneath, rear, and front, may be used with respect to the accompanying drawings. Such directional terms should not be construed to limit the scope of the invention in any manner.
Although the disclosure herein refers to certain illustrated embodiments, it is to be understood that these embodiments are presented by way of example and not by way of limitation. The intent of the following detailed description, although discussing exemplary embodiments, is to be construed to cover all modifications, alternatives, and equivalents of the embodiments as may fall within the spirit and scope of the invention as defined by the appended claims. It is to be understood and appreciated that the process steps and structures described herein do not cover complete process flows for the manufacture of resorbable balloons and methods of administration of time-release therapeutic agents using resorbable balloons. The present invention may be practiced in conjunction with various techniques that may be conventionally used in the art, and only so much of the commonly practiced process steps are included herein as necessary to provide an understanding of the present invention. The present invention has applicability in the field of resorbable balloons or hollow devices in general. For illustrative purposes, however, the following description is presented in the context of a biodegradable (e.g., resorbable, bioresorbable, degradable, absorbable, bioabsorbable, erodible, or bioerodible) balloon for vertebroplasty and kyphoplasty applications and methods of manufacturing a biodegradable balloon, and in the context of biodegradable (e.g., resorbable, bioresorbable, degradable, absorbable, bioabsorbable, erodible, or bioerodible) balloons for delivering therapeutic agents over a distributed time span.
Referring more particularly to the drawings,
A portion of the tubing, e.g. tube 70 (
Regardless of the means used for providing heat, the heated mold 90 may in certain embodiments be configured to provide heat (and/or cooling), for example, in different amounts along one or more of: (a) at least one spatial dimension (e.g., along a longitudinal axis of the heated mold 90), and (b) a time dimension (e.g., at different points in time and/or for different durations). For example, when tubing is inserted into the heated mold 90 such that a longitudinal axis of the tubing is substantially aligned with a longitudinal axis of the heated mold 90, and when as in the illustrated embodiment tubing near the center of the cavity 91 is substantially further from walls of the heated mold 90 than tubing at ends of the cavity 91, greater amounts of heat energy may be provided near the center of the cavity 91 at certain points in time such as during the process of
Electrical coils in an illustrated embodiment of the heated mold 90 may be fabricated to have, for example, greater resistance in a center region of the heated mold 90 than at edges. Such an arrangement may provide greater I2R heating of metal near the center of the heated mold 90, wherein I represents current and R represents resistance. Thus, in an illustrative embodiment wherein the heated mold 90 comprises a block of metal housing electrical coils 92, certain parts of the heated portions of electrical coils 92 may be formed to comprise greater resistances (or other heating structures) to thereby provide varying amounts of heat at the heated portions of the electrical coils 92.
In an exemplary operation, tubing may be fed down a middle of the heated mold 90, and current 93 then turned on to raise a temperature of the heated mold 90. Typically, the heated mold 90 heats the tubing material to a temperature greater than a glass transition temperature, but below a melting temperature, of a material (e.g., a polymer) forming the tubing.
The heated center region 85, which is indicated in
A balloon may be formed in the resorbable tube by forcing heated air through a lumen of the tube at step 25 while, in the illustrated embodiment, continuing to apply external heat, thereby causing the tubing to expand in the selected region.
Exhaust air 111 may be directed out of the tube 70 via, for example, an end of the tube 70 that is opposite to an end through which the fluid is directed. According to this method, the thickness of the wall 97 of the balloon 100 may in the illustrated embodiment be reduced to a thickness of, for example, about 0.005 mm to about 0.1 mm.
In accordance with an aspect of the present invention, tubing comprising a resorbable balloon that is similar to the balloon 100 illustrated in
According to an illustrated embodiment, one or more of a size and a shape of the balloon can be chosen such that the balloon is capable of conforming to sides of the cavity 165 when, for example, the balloon is inflated. In implementations utilizing a catheter, once the material has been delivered into the balloon and, for example, the balloon has expanded to substantially fill the cavity 165, the catheter may be removed from the resorbable balloon, whereby the balloon with the material remains inside the cavity. Thus, a resorbable balloon can be positioned within a cavity and filled with a material to accomplish expansion and conformance of the balloon to interior dimensions of the cavity.
As presently embodied, with a passage of time at least a part of the balloon degrades, causing the material within the balloon to be delivered into contact with a corresponding interior surface or surfaces of or within the cavity. In particular implementations, the resorbable balloon is not removed and resorbs substantially completely within the cavity. Resorption of the balloon can be engineered to occur, for example, after the material has contacted and at least partially reacted, e.g., bonded, with interior surfaces within the cavity. In exemplary embodiments comprising a cavity formed in bone, material comprising bone cement can be positioned within a resorbable, expandable balloon, combined, in some implementations, with one or more of an antiobiotic, analgesic, growth factor (such as Bone Morphogenetic Protein), or a combination thereof, to contact interior surfaces of a cavity formed within bone, thereby permitting one or more of reacting, hardening, and bonding to occur between the material and the bone upon resorption of the balloon. Consequently, risks of one or more of infection and pain can be attenuated or eliminated.
In other implementations, the collapsible, resorbable hollow devices may be nested as illustrated, for example, in
A surgical procedure, which may be a laparoscopic procedure, may be performed, if needed (e.g., suitable or desired), at step 130 to identify a cavity in an anatomical location. As presently embodied, a cavity in a desired anatomical location may also be formed. For example, a cavity may be formed in soft tissue using a tissue expander. Alternatively, a cavity may be formed in a collapsed vertebra of the spine of a patient, wherein therapy is to be performed. As another example, a cavity may be identified in the abdomen or other part of the body of a patient near an abscess requiring antibiotic therapy. Once the cavity is formed or identified, the hollow device may, to the extent inflated, be at least partially deflated at step 140, and the hollow device inserted into the cavity at step 150. The attached conduit, for example, may facilitate insertion and positional manipulation of the hollow device. A therapeutic agent, such as an antibiotic, may be injected into the hollow device at step 160, thereby inflating the hollow device. Alternatively, the hollow device may be inflated before the therapeutic agent is injected. According to other implementations, the inflating may be performed by altering an internal or external physical or chemical environment of the device when the device is in living tissue. The conduit may also be used to transfer the therapeutic agent into the hollow device. The opening may be closed at step 170 after which the conduit may then be removed, if needed (e.g., suitable or desired), from the hollow device at step 180. According to another implementation, the opening is closed after removal of the conduit. In yet another implementation, the opening is closed during removal of the conduit. In yet another implementation, the opening is not closed, as may occur when the device is used to transfer gelling or polymerizing substances as therapeutic agents.
The therapeutic agent may be delivered in a time-released manner according to specific properties of the hollow device. For example, the device may be fabricated with varying thicknesses or with relatively small perforations or holes, sizes of which may be adjusted to achieve a desired rate of delivery of the therapeutic agent. In other examples, more than one collapsible, resorbable hollow device may be employed. A second collapsible device may be inserted inside a first collapsible hollow device, the first device then being injected with one or more or a combination of therapeutic agents. The second collapsible device then may be inflated, and yet another therapeutic agent or combination thereof may be injected into the second device. This process may be continued by nesting a plurality of collapsible, resorbable hollow devices in a manner that should be clear to one skilled in the art from the disclosure provided herein. When a plurality of hollow devices or balloons is employed, openings of the hollow devices may be closed separately either before, after, or during removal of conduits associated with each device. In some instances, the openings may be closed together. In still other examples, nested hollow devices may be made with differing materials or geometry (shapes). Alternatively, space, or lack of space, between the devices can be used to achieve desired patterns of release of therapeutic material.
The collapsible, resorbable hollow devices 200, 220, and 240 illustrated in
Therapeutic agents may have the consistency of, for example, one or more of a liquid, gel, powder, small granules, spheres or chips, a polymerizable substance, and combinations thereof, and likewise, may be chosen from a variety of possibilities. For example, a natural organic substance can be or include one or more of living biological agents (e.g., cells), proteins (e.g., growth factors such as Bone Morphogenetic Protein, and the like), other natural polymers (e.g., collagen, gelatin, fibrin, hyaluronic acid, polysaccharides, elastin, cellulose, polynucleotides), other biological materials, and the like. Combinations of these and similar materials also may be used. In other instances, the therapeutic agent may comprise a synthetic organic substance, such as, for example, one or more of a drug, antibiotic, steroid, glycerol, polymer (e.g., polyester, silicone, polyethylene oxide, polypropylene fumarate, pluronics, polyhydroxymethacrylate, or polymethylmethacrylate), and the like, and combinations thereof. In still other cases, the therapeutic agent may comprise an inorganic substance, such as, for example, one or more of calcium phosphate (e.g., beta-tricalcium phosphate or hydroxapatite), allograft bone, other ceramics or metals, and combinations thereof. The therapeutic agents may be made in combinations from any of the above components or groups or other suitable carrier(s), examples of which may include cells loaded in a pluronic gel or growth factors and antibiotics mixed with an inorganic substance.
For example, first, second, and third resorbable hollow devices 200, 220, and 240 could be designed, respectively, to degrade slowly, at a medium rate, and quickly, and to therefore release, again respectively, first, second, and third therapeutic agents 205, 225 and 245 after, still again, respectively, a long, medium, and short period of time. In one embodiment, first, second, and third therapeutic agents 205, 225, and 245 are different or comprise different combinations or concentrations of therapeutic agents. In another embodiment, first, second, and third therapeutic agents 205, 225, and 245 are the same agent, and the different degradation rates of the hollow devices 200, 220, and 240 serve to release the agent over a relatively long period of time, and/or possibly in short bursts, but, for example, above the therapeutic minimum level 310 and below the maximum therapeutic level or below the toxicity level 315. In yet another embodiment, a hollow device, such as second hollow device 220, can be made to have perforations or holes, or no perforations, and may be covered or layered with another hollow device, such as first hollow device 200 having a faster degradation rate. This arrangement may allow release of the second therapeutic agent 225 through the holes of the second hollow device 220 (i.e., the more slowly degrading device) when the first hollow device 200 (i.e., the more rapidly degrading device) degrades.
In view of the foregoing, it will be understood by those skilled in the art that the methods of the present invention can facilitate formation of resorbable balloons and control of time-release therapeutic agents using collapsible, resorbable hollow devices or balloons. The above-described embodiments have been provided by way of example, and the present invention is not limited to the described examples. Multiple variations and modifications to the disclosed embodiments will occur, to the extent not mutually exclusive, to those skilled in the art upon consideration of the foregoing description. For example, the resorbable balloon may be used for other implanting applications such as a bariatric balloon, breast augmentation balloon, etc. Furthermore, modifications to the above-described manufacturing techniques may include, for example, a continuous extrusion and balloon forming method, and alternative implementations of such techniques may include, for example, extrusion of tubing with one closed end resembling the shape of, for example, a blow molding parison. Other combinations, omissions, substitutions and modifications will be apparent to the skilled artisan in view of the disclosure herein. Accordingly, the present invention is not intended to be limited by the disclosed embodiments, but is to be defined by reference to the appended claims.