Patent Application
20070141245
1. Technical Field
The present disclosure relates generally to filament coating systems and methods, more specifically to systems and methods for coating sutures.
2. Background of Related Art
Surgical sutures are primarily used during surgery to stitch together sections of tissue to aid in post-surgical healing. Sutures are often coated with various substances to improve their knot tie-down characteristics. In addition, coating increases suture's surface lubricity which reduces the friction associated with passing of the suture through the tissue, thereby reducing tissue trauma. Conventionally, suture coatings have been applied by dipping, bushing, wiping, spraying or drip coating. Dip coating involves submergence of a suture line into a coating composition contained in a vessel. Typically, dip coating involves the use of multiple guiding means (e.g., rollers) to pass the suture through the coating composition. For instance, a horizontally passing suture needs to be directed downward into and upward out of the vessel containing the coating composition. Thus, at least one of the guiding roller(s) is positioned within the coating vessel, in contact with the suture before the line is dried. This contact by the roller frequently removes coating material from the suture, thereby reducing the effectiveness of the coating.
Coating has also been accomplished using filling heads. This method involves passing a suture line through a V-shaped notch. Coating composition injected into the notch contacts and coats the suture line. The suture line does not come in contact with guiding rollers until after the coating dries. Although the coating system using filling heads provides more consistent coating for the suture line, the contact time for coating solution to penetrate into suture is significantly less (e.g., less that 0.1 second) than that provided by the conventional dipping coating mechanisms.
Therefore, there is a need for a coating system which allows for more consistent coating at high contact time.
A system and method for coating a suture line are disclosed. The system includes an elongated coating tube having coater heads disposed at both ends thereof. The suture line is fed into the coating tube through an opening in one of the coater heads and exits the coating tube through an opening in the other coater head. Guide rollers that contact the un-coated suture ensure alignment of the suture line as it enters the coating tube. The coating tube is filled with a coating composition to a level above the entry point of the suture line. The composition pours through the openings of the coating tube and is collected by the coater heads so that it is circulated during the coating process to ensure proper ratio of coating agent to solvent. After exiting the coating tube, the suture line passes through a dryer and then is guided by a set of rollers to a winding roll. Then, the suture contacts guide rollers only after exiting the dryer, thereby helping to ensure a uniform coating.
According to one embodiment of the present disclosure, a system for coating a suture line is disclosed. The system includes a first guide positioned to orient the suture line for entry into a coating tube. The system also includes a coating tube having an inlet opening to admit the suture line and an outlet opening through which the suture line exits the coating tube. The coating tube includes a fill opening through which a coating composition is introduced into the coating tube to a level sufficient to submerge a portion of the suture line. The system further includes a second guide positioned to orient the suture line exiting from the dryer.
According to another embodiment of the present disclosure, a method for coating at least one suture line is disclosed. The method includes the step of orienting the suture line through a first guide for entry into a coating tube. The coating tube includes an inlet opening to admit the suture line and an outlet opening through which the suture line exits the coating tube. The coating tube further includes one or more fill openings through which a coating composition is introduced into the coating tube a level sufficient to submerge a portion of the suture line. The method also includes the steps of submerging the suture line in the coating composition filling the coating tube as well as orienting the suture line exiting from the dryer through a second guide.
According to a further embodiment of the present disclosure, a system for coating at least one suture line is disclosed. The system includes a first guide positioned to orient the suture line for entry into a coating tube having an inlet opening to admit the suture line passing through the first guide and an outlet opening through which the suture line exits the coating tube. The coating tube also includes at least one fill opening through which a coating composition is introduced into the coating tube to at least a level sufficient to submerge at least one portion of the suture line, such that the coating composition flows out through at least one of the inlet and outlet openings. The system also includes at least one coater head disposed at each of end of the coating tube, the first and second coater head configured to collect the coating composition flowing through the inlet and outlet openings and a second guide positioned to orient the suture line exiting the coating tube.
The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which:
Preferred embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.
The present disclosure provides for a horizontal dip coating system. The system includes one or more input winders inputting a suture line into a dip coater using a first set of one or more guiding rollers. The dip coater includes a coating tube positioned horizontally with a coater head disposed at proximal and distal ends thereof. The coating tube and the coater heads include openings through its centers to allow for the suture line to pass horizontally therethrough. A coating composition fills the coating tube above the openings of the coating tube through which the suture line passes to coat the line. Any coating composition that leaks out of the coating tube is collected by the coater heads. The coating composition is injected at a higher rate than it leaks out to maintain the composition level therein. In addition, the coating composition collected by the coater heads is circulated throughout the dip coater. In some embodiments, where the coating composition includes solvent carrier and coating agent, solvent content of the coating composition is-monitored and adjusted to ensure that a predetermined ratio of coating agent to solvent is maintained. Upon coating, the suture line is dried and thereafter the line is guided by a second set of one or more rollers to winding rolls.
The input winder(s) 2 disperses the line 10 which may be a monofilament or a multifilament braided suture. Prior to dispersing, the line 10 may be prepared for coating which may involve calendaring the line 10 to facilitate penetration of the coating composition into the interstices of the braid suture, especially where the present system is used to apply a second or third composition to the suture line. An example of a calendaring apparatus and method thereof is disclosed by commonly owned U.S. Pat. No. 5,312,642 entitled “Method and Apparatus for Calendering and Coating/Filling Sutures” which is hereby incorporated by reference in its entirety herein.
The system 1 also includes the air wiper 5 and the air cooler 7. The air wiper 5 is positioned between the dip coater 3 and the dryer 6 and is configured to blow gas (e.g., air, nitrogen, etc.) on the passing line 10 to blow off excess composition. The air cooler 7 is positioned between the dryer 6 and the take-up winder 8 and is configured to blow cool air on the line 10 to provide cooling for the dried line.
As the line 10 is passed horizontally through the coating tube 24, coating composition is applied to the line 10. The coating tube 24 is positioned horizontally and may have a cylindrical shape and may be approximately 1′ to 10′ in length. Typically, the coating tube is 3′ to 5′ long. In addition, the coating tube 24 is preferably manufactured from stainless steel material that does not react with the coating composition. For example, the coating tube may be glass or glass-lined. In addition, if a metal tube is used, it may be desirable to passivate the tube to reduce its reactivity. Passivation methods and materials are within the purview of those skilled in the art. The outer diameter of tube can vary depending on a number of factors such as the number of filaments being treated, the particular coating composition being applied and the desired contact time between the composition and the suture line. Those skilled in the art will appreciate that the cylindrical shape is merely only one embodiment of the coating tube 24 and that it may have a variety of shapes (e.g., rectangular, triangular, or hexagonal cross-sectional shapes, etc.).
The line 10 enters the coating tube 24 through a proximal coater head 18 which is discussed in more detail below with reference to a distal coater head 20, both of which have a circular cross section. It is envisioned that the line 10 passes through dip coater 3 through an opening 91 of the proximal coater head 18, an opening 92 of the coating tube 24, an opening 93 of the coating tube 24 and an opening 94 of the distal coater head 20. The openings 91, 92, 93, 94 are preferably drilled through the center of surfaces 95, 96, 97, 98 respectively, of ceramic eyelets disposed within the proximal and distal coater heads 18, 20 and the coating tube 24 as shown in
The coating tube 24 is filled with a coating composition 31 through a supply tube 56 which is connected thereto via adapter 60 having a male national pipe thread (MNPT) or another type of connecting means. The adapter 60 may be coupled to the coating tube 24 at an angle (e.g., a 135° angle) with the longitudinal axis of the coating tube 24 at the top portion thereof. Those skilled in the art will appreciate that the tubing used to interconnect the components of the dip coater 3 (e.g., the supply tube 56 and other tubing discussed below) may be manufactured from any materials allowing the tubing to be flexible as well as chemically inert to a variety of organic solvents. In one embodiment, the supply tube 56 is made from PTFE and has a ⅜″ diameter. The coating composition 31 is carried into the coating tube 24 via a circulating pump 34 which withdraws the composition 31 from a tank 28 through a tube 58. The tank 28 preferably includes a stirring device, such as a magnetic stirrer driver 26 positioned thereunder, to prevent settling or other separation of the components of the coating composition.
The assembly 20 includes a removable reducing tee 80 configured to drain leaking composition 31. The reducing tee 80 can advantageously have an outer diameter larger than the outer diameter of the coating tube 24 so that the tee 80 fits over the coating tube 24. The return adapter 22 is the reducing portion of the reducing tee 80 and preferably includes an MNPT connection.
The removable tee 80 is connected to the coating tube 24. The distal coater head 20 includes two ceramic eyelets 72, 74. The ceramic eyelet 72 is positioned at the distal end of the coating tube 24 within the reducing tee 80 and the ceramic eyelet 74 is attached at the distal end of the reducing tee 80. The ceramic eyelets 72, 74 are designed to optimize alignment of the openings 93, 94 while minimizing the solvent lost during the coating process as discussed in more detail below. Those skilled in the art will appreciate that the proximal coater head 18 includes the same components (e.g., ceramic eyelet, o-ring, etc.) assembled in the same manner as discussed above with regard to the distal coater head 20.
With reference to
It is also envisioned that the return composition 33 may be recycled during the coating process. Typically, a portion of any volatile solvent in the coating composition may evaporate during the coating process before excess composition 31 flows to the return tank 32. The return composition 33 is contained within the coating system 1 by a plurality of tubes and adapters discussed above to contain the return composition 33 and to minimize solvent loss and vapor escape. Some vapor which does escape is vented through vent headers (not shown) installed above the coating tube 24.
In order for the return composition 33 to be recycled, it must be verified that the desired coating agent composition is maintained. With reference to
In one embodiment, the controller 48 is electrically connected to a solvent pump 96 (e.g., solvent supply means) which injects solvent 35 into the coating tube 24 and a control valve 50 adjusts the flow of the solvent 35 into the return tank 32. The solvent 35 can be injected into the coating tube 24 through the solvent adapter 54 connected to the solvent tank 36 through a tube 52. The solvent adapter 54 is positioned at an angle (e.g., a 45° angle) with the longitudinal axis of the coating tube 24 at the top portion thereof while the drain valve 46 is positioned on the bottom portion thereof. In addition, the return tank 32 includes a magnetic stirrer driver 30 to maintain uniformity of the coating composition throughout the return composition 33 and to mix any added solvent 35. Furthermore, return tank 32 supplies the return composition 33 to tank 28 where it is recycled and continually pumped into the coating tube 24.
In step 152, excess composition 31 is collected. This is accomplished by collecting the composition 31 from the proximal and distal coater heads 18, 20 which are configured to catch excess liquid and from the overflow adapter 40 which prevents overfilling of the coating tube 24 by providing a flow path for any excess composition 31. The excess composition 31 flows to the return tank 32.
Since the coating system 1 relies on constant supply of the composition 31 to the coating tube 24 the composition 31 must be circulated. As discussed above, in some embodiments the coating process involves application of coating agent dissolved in a volatile organic solvent. Therefore, solvent may need to be replenished to maintain the desired coating agent levels within the composition 31. In step 154, the controller 48 analyzes the density/viscosity of return composition 33 to determine whether additional solvent 35 needs to be added. If the density is above the desired limit (e.g., the coating agent to solvent ratio within the return composition 33 is larger than that ratio within the composition 31) then in step 156, the controller 48 adjusts the solvent content. Adjustment of solvent level can be accomplished by signaling the solvent pump 96 which injects the solvent 35 into the coating tube 24 and/or opening the control valve 50 to add solvent 35 into the return composition 33. The return composition 33 is then added into tank 28 from where it is continuously injected into coating tube 24.
Each portion of the suture line 10 should reside within the coating tube 24 approximately between 0.5 second to 10 minutes, preferably the residence time is about 1 minute. As the line 10 the dip coater 3 the line 10 enters the dryer 6 and in step 158, the line 10 is dried. The drying temperature depends on the coating composition used and may range approximately between the ambient room temperature (e.g., 25° C.) at the low extreme and above 100° C. at the upper extreme. It is also envisioned that the dryer 6 uses heated gas (e.g., air, nitrogen, etc.) to dry the line 10. In step 160, the line 10 is cooled by the air cooler 7, which blows cool air onto the dried line 10 and thereafter the line 10 is guided by a second set of rollers 39 (e.g., a roller 38) into the winder 8 where it is wound.
The present disclosure allows the line 10 to avoid physical contact with various machine parts during the coating process (e.g., guiding rollers). The line 10 comes in contact only with the coating composition between the time it is fed into the dip coater 3 and the time it is wound on the winder 8. This is due to the horizontal positioning of the coating tube 24 and the horizontal orientation of the line 10 therethrough, which allows the line 10 to avoid physical contact with components by using a minimal amount of guiding mechanisms (e.g., guiding rollers 13, 39)
Any coating composition known to be useful for coating medical devices may be applied to a medical device using the present methods and apparatus. The coating composition can be a solution, dispersion, emulsion containing, for example, one or more polymeric materials and/or one or more bioactive agents.
In some embodiments, the coating composition includes a polymer, or a combination of polymers. The polymer is most suitably biocompatible, including polymers that are non-toxic, non-inflammatory, chemically inert, and substantially non-immunogenic in the applied amounts. The polymer may be either bioabsorbable or biostable. A bioabsorbable polymer breaks down in the body. Bioabsorbable polymers are gradually absorbed or eliminated by the body by hydrolysis, metabolic process, bulk, or surface erosion. Examples of bioabsorbable materials include but are not limited to polycaprolactone (PCL), poly-D, L-lactic acid (DL-PLA), poly-L-lactic acid (L-PLA), poly(lactide-co-glycolide), poly(hydroxybutyrate), poly(hydroxybutyrate-co-valerate), polydioxanone, polyorthoester, polyanhydride, poly(glycolic acid), poly(glycolic acid-cotrimethylene carbonate), polyphosphoester, polyphosphoester urethane, poly (amino acids), cyanoacrylates, poly(trimethylene carbonate), poly(iminocarbonate), copoly(ether-esters), polyalkylene oxalates, polyphosphazenes, polyiminocarbonates, and aliphatic polycarbonates. Biomolecules such as heparin, fibrin, fibrinogen, cellulose, starch, and collagen are typically also suitable. A biostable polymer does not break down in the body, and thus a biostable polymer is present in the body for a substantial amount of time after implantation. Examples of biostable polymers include PARYLENE™, PARYLAST™, polyurethane (for example, segmented polyurethanes such as BIOSPAN™), polyethylene, polyethlyene teraphthalate, ethylene vinyl acetate, silicone, polyethylene oxide, and polytetrafluoroethylene (PTFE).
In some embodiments, the coating compositions of the present disclosure may also include a fatty acid component that contains a fatty acid or a fatty acid salt or a salt of a fatty acid ester. Suitable fatty acids may be saturated or unsaturated, and include higher fatty acids having more than about 12 carbon atoms. Suitable saturated fatty acids include, for example, stearic acid, palmitic acid, myristic acid and lauric acid. Suitable unsaturated fatty acids include oleic acid, linoleic acid, and linolenic acid. In addition, an ester of fatty acids, such as sorbitan tristearate or hydrogenated castor oil, may be used.
Suitable fatty acid salts include the polyvalent metal ion salts of C6 and higher fatty acids, particularly those having from about 12 to 22 carbon atoms, and mixtures thereof. Fatty acid salts including the calcium, magnesium, barium, aluminum, and zinc salts of stearic, palmitic and oleic acids may be useful in some embodiments of the present disclosure. Particularly useful salts include commercial “food grade” calcium stearate which consists of a mixture of about one-third C16 and two-thirds C18 fatty acids, with small amounts of the C14 and C22 fatty acids.
Suitable salts of fatty acid esters which may be included in the coating compositions applied in accordance with the present disclosure include calcium, magnesium, aluminum, barium, or zinc stearoyl lactylate; calcium, magnesium, aluminum, barium, or zinc palmityl lactylate; calcium, magnesium, aluminum, barium, or zinc olelyl lactylate; with calcium stearoyl-2-lactylate (such as the calcium stearoyl-2-lactylate commercially available under the tradename VERV from American Ingredients Co., Kansas City, MO.) being particularly useful. Other fatty acid ester salts which may be utilized include those selected from the group consisting of lithium stearoyl lactylate, potassium stearoyl lactylate, rubidium stearoyl lactylate, cesium stearoyl lactylate, francium stearoyl lactylate, sodium palmityl lactylate, lithium palmityl lactylate, potassium palmityl lactylate, rubidium palmityl lactylate, cesium palmityl lactylate, francium palmityl lactylate, sodium olelyl lactylate, lithium olelyl lactylate, potassium olelyl lactylate, rubidium olelyl lactylate, cesium olelyl lactylate, and francium olelyl lactylate.
Where utilized, the amount of fatty acid component can range in an amount from about 5 percent to about 50 percent by weight of the total coating composition. Typically, the fatty acid component may be present in an amount from about 10 percent to about 20 percent by weight of the total coating compositions.
In some embodiments, the coating composition contains one or more bioactive agents. The term “bioactive agent”, as used herein, is used in its broadest sense and includes any substance or mixture of substances that have clinical use. Consequently, bioactive agents may or may not have pharmacological activity per se, e.g., a dye. Alternatively a bioactive agent could be any agent which provides a therapeutic or prophylactic effect, a compound that affects or participates in tissue growth, cell growth, cell differentiation, a compound that may be able to invoke a biological action such as an immune response, or could play any other role in one or more biological processes.
Examples of classes of bioactive agents which may be utilized in accordance with the present disclosure include antimicrobials, analgesics, antipyretics, anesthetics, antiepileptics, antihistamines, anti-inflammatories, cardiovascular drugs, diagnostic agents, sympathomimetics, cholinomimetics, antimuscarinics, antispasmodics, hormones, growth factors, muscle relaxants, adrenergic neuron blockers, antineoplastics, immunogenic agents, immunosuppressants, gastrointestinal drugs, diuretics, steroids, lipids, lipopolysaccharides, polysaccharides, and enzymes. It is also intended that combinations of bioactive agents may be used.
Suitable antimicrobial agents which may be included as a bioactive agent in the bioactive coating of the present disclosure include triclosan, also known as 2,4,4′-trichloro-2′-hydroxydiphenyl ether, chlorhexidine and its salts, including chlorhexidine acetate, chlorhexidine gluconate, chlorhexidine hydrochloride, and chlorhexidine sulfate, silver and its salts, including silver acetate, silver benzoate, silver carbonate, silver citrate, silver iodate, silver iodide, silver lactate, silver laurate, silver nitrate, silver oxide, silver palmitate, silver protein, and silver sulfadiazine, polymyxin, tetracycline, aminoglycosides, such as tobramycin and gentamicin, rifampicin, bacitracin, neomycin, chloramphenicol, miconazole, quinolones such as oxolinic acid, norfloxacin, nalidixic acid, pefloxacin, enoxacin and ciprofloxacin, penicillins such as oxacillin and pipracil, nonoxynol 9, fusidic acid, cephalosporins, and combinations thereof. In addition, antimicrobial proteins and peptides such as bovine lactoferrin and lactoferricin B may be included as a bioactive agent in the bioactive coating of the present disclosure.
Other bioactive agents which may be included as a bioactive agent in the coating composition applied in accordance with the present disclosure include: local anesthetics; non-steroidal antifertility agents; parasympathomimetic agents; psychotherapeutic agents; tranquilizers; decongestants; sedative hypnotics; steroids; sulfonamides; sympathomimetic agents; vaccines; vitamins; antimalarials; anti-migraine agents; anti-parkinson agents such as L-dopa; anti-spasmodics; anticholinergic agents (e.g. oxybutynin); antitussives; bronchodilators; cardiovascular agents such as coronary vasodilators and nitroglycerin; alkaloids; analgesics; narcotics such as codeine, dihydrocodeinone, meperidine, morphine and the like; non-narcotics such as salicylates, aspirin, acetaminophen, d-propoxyphene and the like; opioid receptor antagonists, such as naltrexone and naloxone; anti-cancer agents; anti-convulsants; anti-emetics; antihistamines; anti-inflammatory agents such as hormonal agents, hydrocortisone, prednisolone, prednisone, non-hormonal agents, allopurinol, indomethacin, phenylbutazone and the like; prostaglandins and cytotoxic drugs; estrogens; antibacterials; antibiotics; anti-fungals; anti-virals; anticoagulants; anticonvulsants; antidepressants; antihistamines; and immunological agents.
Other examples of suitable bioactive agents which may be included in the coating composition include viruses and cells, peptides, polypeptides and proteins, analogs, muteins, and active fragments thereof, such as immunoglobulins, antibodies, cytokines (e.g. lymphokines, monokines, chemokines), blood clotting factors, hemopoietic factors, interleukins (IL-2, IL-3, IL-4, IL-6), interferons (β-IFN, (α-IFN and γ-MN), erythropoietin, nucleases, tumor necrosis factor, colony stimulating factors (e.g., GCSF, GM-CSF, MCSF), insulin, anti-tumor agents and tumor suppressors, blood proteins, gonadotropins (e.g., FSH, LH, CG, etc.), hormones and hormone analogs (e.g., growth hormone), vaccines (e.g., tumoral, bacterial and viral antigens); somatostatin; antigens; blood coagulation factors; growth factors (e.g., nerve growth factor, insulin-like growth factor); protein inhibitors, protein antagonists, and protein agonists; nucleic acids, such as antisense molecules, DNA and RNA; oligonucleotides; and ribozymes.
A single bioactive agent may be utilized to form the coating composition or, in alternate embodiments, any combination of bioactive agents may be utilized to form the coating composition applied in accordance with the present disclosure.
The amounts of bioabsorbable coating composition to be applied to the suture vary depending upon the specific construction of the suture, the size and the material of this construction. In general, the coating composition applied to an unfilled suture will constitute from about 1.0 to about 3.0 percent by weight of the coated suture, but the amount of coating composition on may range from as little as about 0.5 percent, by weight, to as much as 4.0 percent or higher. For a preferred filled (i.e., containing a storage stabilizing agent) braided suture, amounts of coating composition will generally vary from about 0.5% to 2.0% with as little as 0.2% to as much as 3.0%. As a practical matter and for reasons of economy and general performance, it is generally preferred to apply the minimum amount of coating composition consistent with good surface lubricity and/or knot tie-down characteristics and this level of coating add on is readily determined experimentally for any particular suture.
The described embodiments of the present disclosure are intended to be illustrative rather than restrictive, and are not intended to represent every embodiment of the present disclosure. Various modifications and variations can be made without departing from the spirit or scope of the disclosure as set forth in the following claims both literally and in equivalents recognized in law.
The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/752,685 filed on Dec. 20, 2005, the entire disclosure of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 60752685 | Dec 2005 | US |
