How I close the skin for a total hip or knee replacement

0:00 · Start

Today, I thought it would be good to go into some of the details about what the skin closure is and how it occurs. Now, I only perform hip and knee replacements, so I certainly can't talk for other areas of the body where different suture materials and different closure methods are often used.

0:23 · Hip Replacement Materials

Now, for me, for a hip replacement, you would have noticed that with the direct anterior approach, there are two main incision directions. The main one, or the more traditional incision, is just here on the front of the hip. Now, the bikini line incision, which we perform for some of our females, is at this angle here, approximately 90° to the standard incision. Both incisions are approximately 5 to 7 cm in length, just depending on the size of the patient and the size of the bone underneath.

Now, when we close the skin, it is really important that we close it well. Now, for a hip, there are several layers. Now, with a hip replacement, because we're not cutting or detaching any of the internal muscles or tendons, we don't need to reattach them. So, that means that as we close the tissue layers, it all returns back to its normal position, where the muscles are placed back into their original positions once we remove the retractors.

1:24 · Layers of a hip replacement closure

Now, closing the skin requires, in general, a three-layer closure to the hip. The first layer is a surrounding tissue that's called epimysium. It is a surrounding structure of the muscle that is the sheath that the muscle sits in. We never damage the muscle fibres, but that sheath is something that we open during the surgery so we can move the muscles up or down during the operation. Now, when we perform the surgery, we like to close that sheath, and that encompasses or holds in some of the ongoing fluid and bleeding that can occur after the operation.

The next layer is the fat layer. We close the fat layer with a dissolvable suture. It is a very thin suture and it is just under the skin, approximately 1 mm underneath the skin and is a dissolvable suture. Actually, all of our sutures for the hip replacement closure are dissolvable, but they all are slightly different in strength and slightly different in thickness. The skin layer is using a very specialised suture.

It is a barbed suture, similar to a very, very tiny barb on a fish hook. It has hundreds of these little barbs on the suture, which enable us to close the wound under the skin where no sutures are required to be removed later. It also means that we no longer have to tie any knots on that very superficial layer. Now, that brings the skin very closely together and it helps the skin edges heal well.

3:01 · Dressings of a hip replacement

On top of that layer is then a layer of antibacterial glue, which we use to seal the wound and prevent any sort of microbes or any fluid or anything from getting in or out of the wound. Now, in general, it is not a perfectly watertight layer, but it certainly acts to decrease anything going in and out of the wound. On top of that are some steri-strips, usually three or four steri-strips, a white indicator strip and then the dressing over the top.

Because we use so many layers of dressings over the wound, it does mean that anything from the outside air is very difficult to get in under the dressing. So, don't feel concerned if the edges of the dressing start to fray slightly as you go through your 2-week recovery before you come back to see myself and the nurse for that dressing change. Now, all of the sutures, like I mentioned in the hip, are dissolvable.

3:51 · Dissolvable sutures

And that means that over the course of the first 3 months after surgery, they dissolve at different rates. The skin suture dissolves the quickest, and the deeper sutures dissolve the slowest.

4:05 · What is a stitch “abscess”

Now, as they dissolve, occasionally you can get small reactions just under the skin, which may make the wound ever so slightly red, and occasionally you might see just a tiny little bit of what looks like a white material coming through the wound. Now, often this is not pus. It is often just a sterile stitch abscess that occurs as the body tries to remove the foreign material from the body.

It can be very normal, and certainly nothing to be concerned about, but like with all of my patients, please send me a photo if there are any indications that you're concerned.

4:40 · Knee replacement closures

Now, for the knee replacement, there are slightly longer sutures for that, as the knee wound is a bit longer. Now, if you're one of my patients, you'll have a curved incision around the outside of the knee, provided that you've never had any surgeries or major cuts on the knee before. Now, that lateral incision, as you'll see from some of my previous videos, is there so that you have an improved kneeling capability after the surgery.

5:04 · Type of incision for a knee replacement

It is a very aesthetic cut, because it means that as things heal, if you look directly at the wound once it's fully healed, it is actually very difficult to see, which is something that a lot of my patients enjoy. Now, the suture material for a knee replacement is very similar to what I just described for the hip. It's composed of dissolvable sutures through the layers, with the final two layers being the fat and the skin.

There is one more important layer. Now, that is on the inner aspect of the knee. Now, I access all of my knees on the on the inside, even though the skin cut is on the outside.

5:40 · Internal vs external incisions

This creates a double-breasting phenomena over the knee joint, which means that in the very unlikely case of any bacteria or microbes getting into the skin layer, it is very difficult for it to travel all the way across to the other side of the knee to enter the actual knee joint. Now, the skin sutures on the inner aspect of the knee need to be quite a strong suture as it needs to withstand all of the muscle tension that occurs around that area and hold in as much of the fluid bleeding and swelling that occurs after surgery.

All of these layers are dissolvable and over the first 3 months, just like with the hip, they will all dissolve to nothing. And similarly to the hip, it is possible for you to get very small stitch reactions to that. Again, if you're concerned to let us know as soon as you are so that we can address them as early as possible. I hope that goes into a little bit of detail for you about what we use to close the skin.

Occasionally, there are differences if people have some allergies to some of the skin sutures or they found that they've reacted to them from other surgeries in the past.

I hope that's helped and I look forward to seeing you again for the next video. Thank you.

Transcript edited lightly for readability.