Tips on suturing
Suturing is vital to the success of aesthetic and functional soft tissue work. The handling and theory of soft tissues is something that is terribly taught in dental school. The exposure to this subject should be through oral surgery and periodontics experience but this is something that is often absent either due to the lack of appropriate patients, lack of appropriate training staff or due to interdisciplinary politics.
The placement, direction and tension of sutures matters hugely to how well the soft tissues react in the healing process. When primary closure is possibly this will result in the fastest healing and sutures can be removed earlier. Loss of primary closure can result in poor or failed grafts.
Below are some tips I picked up at the course on how to go about the suturing process.
-There are two types of suture : Anchoring and approximating. Anchoring sutures are far from the wound edge >1cm (approximately the length of the needle) where there is more blood supply and are drawn in tight to draw the wound edges towards each other. Horizontal mattresses can be used along the length of the flap to draw the tissues together and take the tension off the approximating sutures. Approximating sutures are tied close to the wound edge ~2mm and bring the tissues into close proximity with each other. These should be tension free as tensioned sutures will dig into the tissues which will result in loss of approximation and the pressure can cause necrosis at the wound edge. Both will result in loss of primary closure delaying healing. If there is primary closure, approximating sutures can be removed at 7 days post operatively. Anchorage sutures need to stay in longer to keep tension off the flap as the muscles can still pull on the wound.
-Monofilament sutures have a springback effect where if they are tied in an oval (0) they will spring back into a circle (O). Approximating sutures shouldn't be tied completely closed as they will tension the wound. Instead they should be tied without tension with a loop and the spring back effect of the suture will bring the wound edges together The anchoring sutures should draw the flaps together so that the edges can be approximated without tension. For this to be possible, the flap has to be mobiel enough to reach its destination without tension. E.g in bone grafts, where the flap has to be reach its pre-raised location it will not be possible as the bone graft material and membrane will occupy space under the flap. Therefore the flap has to be split or released before the graft material is placed.
-Needle sizes is chosen based on the surgical site: aim to use 12mm needles for anterior sites and 15 for posteriors. The wider dimension buccolingually for molars makes it more difficult to use a short needle.
-For fine soft tissue work, suture sizes or 6/0 or 7/0 should be used. Having used these sizes, handling a 3/0 or 4/0 suture seems barbaric to me.
-Hold the needle 2/3 from the pointed end. The part where it attaches to the suture is hollow and so is very weak. Compression form suture forceps will damage this end.
-Practice placing the needle on the bib and using the tweezers to manipulate the long end of the suture instead of your fingers. With practice this becomes faster than using fingers as it saves time picking up and dropping the tweezers.
-First throw: Enter the soft tissues with the needle at 90 degrees to the tissue the rotate the forceps to slide it through. Once you are through to the other side, pull the long end until the short end is near the tissue. use tweezers to hold the long end giving yourself enough room from the wound that you can loop the sutures around the forceps without pulling the short end any further. Hold the tweezers/your fingers still and use the suture forceps to wrap around the long end of the suture. Form 2 loops away from yourself and grab onto the short end of the suture with the forceps. Once the short end is secure in the forcep place the forcep near the wound surface on the opposite side and pull on the long end tight. The side of the short end should swap with each throw
-Second throw: You won't be able to maintain knot tightness with the first throw as once the suture is moved it will loose. Loop the suture 1 throw towards you in the way described above, grab the short end and place the short end towards the original side. Raise both ends of the suture above the wound surface to slightly stretch the tissue. Once it is tightend and released, a tension free suture will be produced. Pull the long end to tighten the knot. For 6/0 and 7/0 sutures, 2 throws should be sufficient.
-Cut the suture 3mm from the wound surface
The placement, direction and tension of sutures matters hugely to how well the soft tissues react in the healing process. When primary closure is possibly this will result in the fastest healing and sutures can be removed earlier. Loss of primary closure can result in poor or failed grafts.
Below are some tips I picked up at the course on how to go about the suturing process.
-There are two types of suture : Anchoring and approximating. Anchoring sutures are far from the wound edge >1cm (approximately the length of the needle) where there is more blood supply and are drawn in tight to draw the wound edges towards each other. Horizontal mattresses can be used along the length of the flap to draw the tissues together and take the tension off the approximating sutures. Approximating sutures are tied close to the wound edge ~2mm and bring the tissues into close proximity with each other. These should be tension free as tensioned sutures will dig into the tissues which will result in loss of approximation and the pressure can cause necrosis at the wound edge. Both will result in loss of primary closure delaying healing. If there is primary closure, approximating sutures can be removed at 7 days post operatively. Anchorage sutures need to stay in longer to keep tension off the flap as the muscles can still pull on the wound.
 |
| Two types of sutures: In this diagram to close a flap, the two types of sutures are demonstrated. Horizontal mattresses with large bites take all the tension of the flap. Simple interrupted sutures with smaller bites approximate the edges of the wound. |
-Monofilament sutures have a springback effect where if they are tied in an oval (0) they will spring back into a circle (O). Approximating sutures shouldn't be tied completely closed as they will tension the wound. Instead they should be tied without tension with a loop and the spring back effect of the suture will bring the wound edges together The anchoring sutures should draw the flaps together so that the edges can be approximated without tension. For this to be possible, the flap has to be mobiel enough to reach its destination without tension. E.g in bone grafts, where the flap has to be reach its pre-raised location it will not be possible as the bone graft material and membrane will occupy space under the flap. Therefore the flap has to be split or released before the graft material is placed.
 |
| Approximating sutures: Monofilament sutures are placed without fully tightening the knot. Both ends of the suture are stretched before tying the second knot which will stretch the tissue. Therefore when the knot is tied and the suture is cut the tissue will rebound and will be tension free. The rebound effect of monofilament sutures will draw the edges of the tissue together without tensioning the tissue with a tight knot |
-Needle sizes is chosen based on the surgical site: aim to use 12mm needles for anterior sites and 15 for posteriors. The wider dimension buccolingually for molars makes it more difficult to use a short needle.
-For fine soft tissue work, suture sizes or 6/0 or 7/0 should be used. Having used these sizes, handling a 3/0 or 4/0 suture seems barbaric to me.
-Hold the needle 2/3 from the pointed end. The part where it attaches to the suture is hollow and so is very weak. Compression form suture forceps will damage this end.
-Practice placing the needle on the bib and using the tweezers to manipulate the long end of the suture instead of your fingers. With practice this becomes faster than using fingers as it saves time picking up and dropping the tweezers.
-First throw: Enter the soft tissues with the needle at 90 degrees to the tissue the rotate the forceps to slide it through. Once you are through to the other side, pull the long end until the short end is near the tissue. use tweezers to hold the long end giving yourself enough room from the wound that you can loop the sutures around the forceps without pulling the short end any further. Hold the tweezers/your fingers still and use the suture forceps to wrap around the long end of the suture. Form 2 loops away from yourself and grab onto the short end of the suture with the forceps. Once the short end is secure in the forcep place the forcep near the wound surface on the opposite side and pull on the long end tight. The side of the short end should swap with each throw
-Second throw: You won't be able to maintain knot tightness with the first throw as once the suture is moved it will loose. Loop the suture 1 throw towards you in the way described above, grab the short end and place the short end towards the original side. Raise both ends of the suture above the wound surface to slightly stretch the tissue. Once it is tightend and released, a tension free suture will be produced. Pull the long end to tighten the knot. For 6/0 and 7/0 sutures, 2 throws should be sufficient.
-Cut the suture 3mm from the wound surface
I don't quite understand what you mean by not fully tightening the knots. Do you mean both throws are not tightened? I always keep the first throw loose, but the subsequent ones as tight as possible.
ReplyDeleteI thought the finer the suture, especially if monofilament, the more throws you need, but corre t me if i am wrong. I rarely do less than 3-4 throws.
Hi Mate,
DeleteThanks for your question. I have done the same as that is what I was taught at dental school. For example with a 3 sided flap for a surgical extraction of a lower 6 which is kind of line the diagram in the post I would normally put 2-3 tight simple interrupted sutures on the gingival margin to hold the flap in place and 1-2 sutures on each relieving incision. I found that when I reviewed these surgeries in post op that the sutures were always loose or had come undone and the flap was healing ok but the edges of the would looked ugly and white but I took this as normal healing.
The important thing to note in this example is that the sutures to hold the flap are approximating the wound edges as well as providing tension to hold the flap up. The problem with this is that every time the patient moves their cheek, the flap is pulling on the edges of the wound and trying to move the flap from the position that you left it. This would be fine if the sutures could hold it still but as the sutures that hold the tension of the flap are on the wound edge and simple interrupted sutures will cross the wound edge, if these sutures are tight (in that the loop is tensioning the wound edge) the tissue around the suture will die and the suture will pull out causing a failure in your closure and poor healing. As the blood vessels tend to come first from the distal and curve upwards towards the gingiva, the worse position for these tensioning-approximating, tight sutures will be at the relieving incision as the pressure will be across blood vessels and the tissue will die very quickly.
To resolve this issue, the idea explored in this post is having anchoring sutures (represented in green) first that are far from the delicate wound edge that drag the flap up to where you want it to end up. When the cheek moves now there is plenty of tissue around the sutures to protect against necrosis. When these anchoring sutures are put in place and you place the flap onto the bone the wound edges should line up without stretching of the tissue. When you pull the cheek and check the mobility of the flap, the the flap on the gingival side of the anchoring sutures should not move at all. Now you can achieve tension free closure of the wound edge.
Perhaps I could choose my words better with regards to the approximating sutures. these go next and are only there to ensure that the wound edges does not move from their position. they should be "tight but tension free". So I didn't mean that the knot shouldn't be tied tight because it should be or it will come undone but I meant that the loop shouldn't be completely closed because it will strangulate the blood supply at the wound edge. The goal now changes from the wound edge sutures dragging the flap AND holding it in place to just holding it in place so this doesn't need to be tied tight.
...
...
DeleteAs far as I am aware, some finer sutures can work with only 2 throws if tied correctly. Some still need three but you'll have to play around with the different types to see which ones allow you to do that. In my mind I compare it at both ends of the spectrum i.e a big rope and a thin string. I can tie a shoelace tight with just two knots because it's thinner, stretchier and the knot ties tighter whereas due to the thickness of a rope I have to add extra knots to hold it in place because even though it takes more strength to tie the knot, the rope doesn't adapt as well against itself so can't be tied as tight. It's not a perfect analogy but it makes sense in my head. I have the pleasure of using 3/0 sutures the other day and no matter how hard I pulled, the knot wouldn't close completely so found that I had to add extra throws to stop it from opening up. The only issue adding extra throws is that it makes the knot bigger which can leave a bigger scar on the tissues at the point of the knot and will cause more plaque accumulation.
The number of throws in this post isn't the critical part, sutures are more likely to pull out if the suture at the wound edge is over tensioned. This occurs not because the knot comes undone but because the tissue necroses and the knot actually pulls through the tissues to the other side.
Let me know if that made sense at all.
Thanks for clarifying mate. I understand what you mean, it's a fine line between tight and tensioned. Hope you're doing well.
Delete