Do either of the knots below have a name? The first is basically a knot used by Ethicon for ratcheting down on tissue and locking. The second is a modification I created of the SMC knot that locks when the short end is pulled on. It is more secure than the SMC and loosens less than the Dines Knot. Thanks.
These knots are for extracorporeal surgical knot tying for laparoscopic operations. I am not seeing names for them.
In laparoscopic general surgery and orthopedic arthroscopic surgery, there is a need for knots which are tied outside the body and slid down through tubes to secure tissue within the body. Although there are laparoscopic techniques for tying knots within the body, generally braided suture is used. In most surgery, monofilament sutures (permanent - like polypropylene or nylon, or dissolving monofilament) is preferred to braided suture as it causes less cutting of tissue, less scarring, and has a higher resistance to infection.
The most commonly described ratcheting knots are the Roeder (with various modifications) or Meltzer knots. These are semi locking, and work somewhat like a Prussik knot. The Ethicon knot is modified from what is probably an incorrect diagram on a patent: http://www.google.com/patents/EP0477020A1?cl=en
True locking knots, where a loop flips within the body, are less commonly used. These are similar to the technique used to tie a bowline knot by forming a slip knot and putting the end through the loop. The problem with these types of knots (Weston, SMC, Dines, etc) is that if they are tied down tightly, they may not flip the loop. If the loop flips, they may loosen slightly before becoming secure. For that reason, I don’t see them commonly used.
Good day Isleofgough and welcome.
Thank you for the information you’ve presented.
Congratulations for figuring out a knot that improves some aspect of a particular application. Hopefully it will be adopted after extensive testing. I surmise that the additional bends/kinks in the tying help, especially with the environmental conditions it will meet.
I suppose there could be mods to other accepted extracorporeal sliding loop knots that would increase their security without too much fuss.
As for a name?? Naming is all over the place and it is probably first come, first serve to attach a moniker. (If that is important.)
I have not seen this before and all it can take sometimes is to take a known knot as a base and then change the routing of one part or add something and it is then “new”.
http://www.laparoscopyhospital.com/extracorporael_knot.html is an interesting site if you have not looked at it by chance.
So, how will you test the knot you’ve presented?
SS
Thank you for the links to a site on extracorporeal suturing.
There are dozens of articles comparing various such knots for different sutures, and actually the orthopedic literature has better discussion of these. Things get confusing, as not only are there lots of modifications of knots (simple Roeder, Savoie Roeder, Lieurance Modified Roeder, etc.) but sometimes the knots named in the articles are incorrect. Surgery also gives different names to existing knots (like using Nicky for Taut line hitch, and Tennessee slider for upside down sliding granny knot). My experience is that the security of various knots depends a lot on dressing the knots, and this is not described in papers. In addition, there is little discussion of how tightly the knot goes down, only how resistant to slipping or breakage after it is tied. A super surgeon’s knot with lots of winds on the initial knot will pass tests used to test slippage, but will never go down tightly. Every true locking knot I know either is unreliable without extra throws or slips back slightly before catching. A loose knot that will not tighten is generally the worst option.
Surgeons sometimes just through alternating half hitches down pulling first on one end and then another. The Revo knot is an example of this. However, it is common that in sliding down a knot, one end gets to short to tie outside the body. There are lots of options for suturing inside the body with long instruments, but suture choices are more limited and it is technically very difficult if the camera is at an angle to your suturing. Sometimes it is like mirror writing.
I do not know how best to test these knots. A simple method I use with residents is to tie around the top of a wine bottle and then to test for slippage by trying to pull the knot down the narrow part to see if it slips or breaks. I have used tensiometers for testing, but there are a lot of factors involved that do not replicate actual use. I help with a simulation lab, and any suggestions would be welcome.
You are welcome.
I do not know how best to test these knots. A simple method I use with residents is to tie around the top of a wine bottle and then to test for slippage by trying to pull the knot down the narrow part to see if it slips or breaks. I have used tensiometers for testing, but there are a lot of factors involved that do not replicate actual use. I help with a simulation lab, and any suggestions would be welcome.
Just a thought: Use lubricated, small diameter natural rubber tubing. (Inside a matchbox, eyes closed. Grin)
Or thin strands of ballistic gel.
Tubular pasta.
Not perfect, but it might simulate some aspects.
SS
Thank you for your suggestions. I named the new knot “Sheila knot”. See link:
https://app.box.com/s/7au64gjtmg4wl6yt5ogyyhp0xb04bwjz
I updated the surgical knots to include laparoscopic knots, the Mayo clinic TSOL knot, and several locking knots.