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Doug Turner wrote: reusable needle. Now days it is the same nylon but custom packaged with a needle already swagged onto to the line. Some newer soluble suture materials look and feel very similar to nylon or polypropylene but are a bit more "springy" and their knots have disconceting habit of un- ravelling. This is a property of the material, not its location. Have you considered contacting the manufacturer of the material? -- Karl Pollak, Richmond, British Columbia Sea Scouting in Canada at http://www.seascouts.ca/ |
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.. Have you considered contacting the manufacturer of the material? No, but they have a disclaimer in the product information section warning about its knot holding properties. Doug |
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Doug Turner wrote in message 1.5...
(Brian Grimley) wrote in om: ..... Another variable to interpret the "knot-in-a-sponge - warm rinse cycle" would be the "spring" in the thread. By "spring" I mean the force of the thread to straighten itself when bent....... Hi Brian, I think this might be another term for "memory". A rubber band (besides being very stretchy) has a lot of memory. You can bend or kink it as much as you like and it will resime its initial shape. Stainless steel wire on the other hand has little memory. Once bent or deformed it retains that shape. This tends to make knots more secure. ... A suggestion for a generally accepted term for unravelling when not loaded is UNL (Unravelling when Not Loaded). I think UNL trips lightly from the tongue and acronyms are always fun and popular. :-) Sounds good too. But what really surprises me is there is not an already accepted term. ...As a "brain storming" suggestion, perhaps the suture should be manufactured so that the needle and the first 1/2 of the suture are friendly to piercing tissue. The second half changes (perhaps with colour for identification) to have properties to reduce UNL. Mostly a long thread is used to tie multiple sutures like you see in a repaired skin wound. Each suture is tied near the end of the long thread, cuting the tail off near the skin and re-using the now shortened thread until none is left. ...If you are Doug Turner, the "orthopod", I expect, when you read this, to hear your groan where I live - 1/2 way around the world. 'Tis me. ...I give up...how did you find me? Doug Turner The memory quality mentioned earlier is, I believe, very significant to this entire discussion, since even the best tied knot will tend to unravel if the coefficient of friction is too little to adequately secure a knot, especially if it is not under any real load or a changeable load. Dealing with a wet environment and 'slimy' tissues and juices, one can hardly expect an essentially smooth fiber to resist movement as its memory tries to open the knot. When synthetic fibers are made, the maker is primarily concerned with ease of manufacture which mostly involves straight linked polymers, of course, since that creates maximum profit, and there is no reason to assume so much nobility on the part of makers of medical sutures that they are not also bound by this normal dictum of the business world. They do not exist to help surgeons; they exist to make a profit -- a BIG profit! This means that they are going to publish disclaimers and tacitly blame the users (surgeons) for poor knot tying technique since that takes all responsibility from their product. What to do? Is it possible to find someone medical who is so prominent that he can influence the OWNERS of these companies making the suture material to change to EMBOSSED fibers such as are often made by the makers of fabric synthetics to address the specific tension requirements of a designed fabric? The process of EMBOSSING (sometimes called CRIMPING) the surface of a synthetic as it exits the spinarettes of the extruding machine, has long been used by textile fiber makers to achieve the degree of 'tack' necessary for a weave or knit to hold against other fibers. This Embossing or Crimping process does add another cost step to the making, and also will somewhat reduce the strength of the fiber, so there is, of course, a cost/benefit analysis to be done. The maker will always resist any change unless they can see a profit motive involved, since that is their business, not surgery. Perhaps an article on this problem in JAMA or LANCET or other prestegious journal will bring others to your cause and put subtle pressure on the makers to improve their product. Yes, a surgeon usually does not have time to do the tests that the journals will expect to underpin your conclusions, but if you have a friendly relationship with a manager at one of the suture makers, it is possible that you can get him to sponsor a test of materials (NOT knots) as to coefficients of friction under 'wet and lubricated' conditions. If he will agree in advance to allow you to publish his results (with credit to his firm, of course!) it is possible that you will have the nucleus of an article with documentation of tests, and then even if his firm declines to revamp their fibers (which they might for business reasons), other firms may take heed and see an opportunity to outsell their competitors by claiming dominance of the market for suture materials. You might in fact contact Textile Engineers through such directories as Davison's Textile Blue Book (at larger libraries or on-line) to get their expert opinions to insert in your article in the medical press. There are departments of textile science at some universities, and perhaps a dean or professor at some such would be willing to undertake a study with their students to determine definitavely what the benefits/merits/faults of uusing/designing special Embossed fibers would be to the medical arts. Such contacts might also lead you to makers who would be more sympathetic to your needs, or merely wanting to penetrate the medical materials field. These people think in commercial terms, not medical ones, so you must appeal to their motives if you expect results. Clearly, it is not the fault of the surgeon who learns all reasonable knots, but is defeated by the new synthetic materials, and even the traditional silk under some circumstances. Since failure of knots in sutures or the like might end up as the cause in a malpractice suit, it is quite possible that some providers of malpractice insurance would be willing to fund a study at some school, with perhaps you doing the write-up for a medical journal. If you can site specific cases of suture/knot failures leading to costly or horrible results, you would be that much more ahead of the naysayers. Best Wishes! |
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