Patent Application
20070270691
Referring now to
Still referring to
Besides tubing (such as shown in
Those skilled in the art will appreciate that the PEEK and BiO3 may be obtained from a number of commercial sources. For example, PEEK may be commercially obtained from Invibio, Inc. of Greenville, S.C., and BiO3 may be commercially obtained from various sources. We have obtained such materials from a compounder, Fosters Corp., of Putnam Conn. The PEEK may be obtained in different colors and pellet sizes, and the BiO3 may be obtained in a powder form. The BiO3 powder may be mixed with the PEEK pellets, and the mixture may then be heated and further mixed to provide the desired composition containing the mixture of the BiO3 in the PEEK. The resulting composition can then be molded to provide implants of a desired size and shape. Such implants can include spinal cages, screws, stents, and the like. In addition, those of skill in the art will appreciate that the resulting composition can alternatively be extruded, such as in a conventional manner for PEEK alone. Extrusion may be particularly useful in forming tubes made of the desired composition, including catheters, stents, and other implants. In addition, such articles can be machined to obtain desired shapes and sizes.
Besides tubing, catheters, grafts, and stents, the composition comprising PEEK and BiO3 can be used for a wide variety of implants for use in the human body. Among other things, the PEEK and BiO3 composition as described above can be used for any of the following types of implants: spinal cages, suture anchors, spiked washers, surgical screws, femoral implants, balloons, intracardiac pumps, heart valves, finger joints, hip and femoral bone replacements, bone screws and pins, dental posts and caps, and so forth.
PEEK provides a number of advantages. PEEK is biocompatible and biostable. PEEK articles may be easily sterilized, a conventional requirement for articles to be used in vivo with human patients. PEEK has inherent lubricity. PEEK is extremely strong—carbon fibers can be added to PEEK in order to obtain an article with mechanical properties of strength substantially the same as those of healthy human bones. PEEK typically has a melting point of about 343° C., a crystallization peak of about 160° C., and a glass transition temperature of about 145° C. PEEK can be extruded and injection molded by conventional techniques.
Those skilled in the art will also understand and appreciate that, depending on the particular application involved, other alternative polymers may be used in place of PEEK. Those skilled in the art will appreciate that in place of PEEK, other polyaryletherketones may be used as the polymer component of the composition. For example, the polymer commercially available under the trademark PARMAX, which is commercially available from Solvay Advanced Polymers of Alpharetta, Ga., has appropriate mechanical and chemical properties such that it can be mixed with BiO3 to obtain a radiopaque implant with the desired characteristics. PARMAX is a self-reinforcing polymer that is an amorphous, melt-processable engineering thermoplastic. Other appropriate polymers include polyetherketone, polyetherketoneketone, polyphenylsufone, polyetherimide, and the polymers commercially available under trademarks RADEL®, which is also commercially available from Solvay Advanced Polymers, and ULTEM (polyetherimide), which is commercially available from the General Electric Company of Schenectady, N.Y.
Those skilled in the art will also appreciate that other polymers may be used in accordance with the invention. Such other polymers may include liquid crystal polymers, polyphthalamides, and polyarylamides. These latter polymers are either self-reinforcing polymers or can be reinforced with glass or carbon fibers. Each of these latter polymers are biocompatible in connection with short term blood contact.
In addition to the above polymers, the invention in another embodiment involves the use of a composition of polytetrafluoroethylene (PTFE) and BiO3. The composition can be prepared such as described above, such as with BiO3 in the amount by weight of from about twenty percent (20%) to about thirty percent (30%), by mixing PTFE and BiO3 in powder form. The mixture can then be fabricated using conventional paste extrusion techniques and equipment. For example, the mixture of PTFE and BiO3 can be combined with a liquid to disperse the PTFE and BiO3 powder mixture, the dispersion blend may be extruded, and then the liquid may be removed, such as by drying or sintering. Those skilled in the art will appreciate that the PTFE and BiO3 need not be mixed together in powder form first, but can be added to the liquid one after another.
Those skilled in the art will appreciate that implants made in accordance with the present invention may be either short term or long term implants. Indeed, articles made in accordance with the invention need not be implanted, but may be inserted into a patient's body for use during surgery or other medical procedures, then removed from the patient's body when the surgery or other procedure is finished. (Although regulations of the U.S. Food & Drug Administration (F.D.A.) define an “implant” as a “device that is placed into a surgically or naturally formed cavity of the human body if it is intended to remain there for a period of 30 days or more,” those skilled in the art will appreciate that “implant” as used herein is also intended to include even those articles temporarily placed into a human body, as well as in any other animal body, including those of mammals other than humans.) “Implant” as used herein is intended to include any device which is inserted wholly or partially into a subject's body cavity (whether the subject is human or not), including those types of devices deemed an implant pursuant to F.D.A. regulations, such as those found in 21 C.F.R., Parts 870, 872, 874, 876, 878, 880, 882, 886, and 888 (as of April 2005). Those skilled in the art will also understand and appreciate that, although most of the foregoing discussion involves human patients, the articles and implants made in accordance with the invention may be useful in other areas as well, including in veterinary situations in which the patient is a cow, dog, cat, horse, or other mammal and not a human patient.
Radiopaque articles made in accordance with the present invention may be used in a variety of situations. As noted, such articles may be used as implants in a variety of applications. Such implants may be either short term implants or long term implants. In addition to use as implants, however, articles made in accordance with the invention may be used during surgical and other medical procedures. For example, a catheter (not shown) may be provided that has been made from a composition of PEEK and BiO3, with about thirty percent (30%) by weight of the composition consisting of BiO3. The catheter may be formed as a tube of a desired inner diameter size and outer diameter size. In addition, the catheter so formed may be of a desired length. Such a catheter in accordance with the invention may be used by inserting it into a patient's body, such as into an incision made to allow drainage from within the body. In addition, such a catheter may be inserted into a blood vessel and then guided by an operator (such as a physician) to a desired location, such as a blocked blood vessel in connection with coronary angioplasty. During the procedure, the operator can view a fluoroscope of a conventional type in order to identify and precisely locate the catheter as it is guided to the desired location in the patient's body. Once the operation is completed, the operator can then remove the catheter from the patient's body. Besides applications in coronary surgery, such a catheter may be used in any type of surgery in which the precise location of a catheter is desired, such as in neurological, ophthalmic, cosmetic, and dental surgeries, among others. In such situations, the use of a radiopaque article made in accordance with the present invention will be advantageous, as doing so allows the operator to determine the precise location of the article within the patient's body via the use of conventional X-ray, fluoroscopy, and/or magnetic resonance equipment. In addition, articles made in accordance with the present invention also are advantageous in that they may be fabricated to varying degrees of radiopacity. Referring back to
Those skilled in the art will appreciate that the foregoing description of the invention is of a preferred embodiment and of certain specific alternative embodiments, and that various changes, modifications and other variations and adaptations thereof may be made without departing from the scope and spirit of the invention as set forth in the claims. The specific embodiments, and the dimensions, materials, and the like are merely illustrative and are not intended to limit the scope of the invention, as set forth in the claims.
