What you see on the surface of a wound is not the whole story.
Understanding the basics of how your surgery will be performed is a critical component of being an informed patient. It also helps to know what to expect the first time you see your wound as well as what your role is in the wound care process. The more knowledge you have about healing – what helps and what doesn’t – the more likely you are to have the successful outcome you’re looking for with your joint replacement.
Types of Wound Closure
There are three types of wound closure: primary, secondary and delayed primary closure. A wound generally heals in 4 to 6 weeks.
Primary wound closure (sometimes referred to as healing by primary intention) is what takes place after surgery. There is no tissue loss at the wound site and the wound edges can be cleanly brought together so healing begins very quickly. Scars resulting from this type of wound closure are generally less pronounced.
Secondary wound closure (healing by secondary intention) occurs in wounds where the edges cannot be brought together. This can occur when a primary wound closure fails to heal properly or in cases where a post op infection has resulted in significant tissue damage or loss. The photo at left shows a wound opening resulting from infection in one of our BoneSmart members. In these wounds, a granulation tissue matrix must fill in the wound because the edges cannot be brought close enough together to heal. The resulting scar is normally larger because of the granulation.
Delayed primary wound closure (healing by tertiary intention) is a combination of primary and secondary closure. In cases where a wound is heavily contaminated, it is cleaned and left open for several days to reduce the chance of infection and then surgically closed. This type of wound closure normally occurs in situations such as tissue grafts and does not usually pertain to joint replacement surgery.
Most people have seen examples of what you can expect the external wound to look like once you are in recovery – the stitches, staples, adhesive skin closures (such as 3M Steri-Strips) or surgical glue. But closing a surgical wound is actually done in layers and the surgeon’s real work is done below the surface skin level.
Each layer of a wound has its own unique type of sutures. Using 3 or 4 sutures, the joint capsule containing your new implant is closed first. It is followed by the surrounding muscles and fascia, a white fibrous outside layer of the muscle. Sutures in the muscle and fascia are the main anchors that hold the wound closed. The fat layer is closed next followed by the skin layers. These internal sutures are made with a special material that is slowly absorbed by the body.
The sub-dermal layer of skin is the 2-3 mm of tissue right below the surface skin. It is closed with a single long stitch that runs the length of the wound.
These subdermal or subcuticular stitches are the ones responsible for holding the skin closed. In the photo above you can see the stitches being placed. Once that is complete, the surgeon will pull both ends of the thread and the skin edges will be drawn together.
Here is another version of subdermal stitching using non-absorbable monofilament nylon that is knotted at each end. The ridge of skin is made by the surgeon as he draws the wound closed.
For removal, the knots are clipped and the nylon thread is gently pulled out.
The final step is for the surface skin or dermis to be closed. A surgeon historically has had several choices – staples, sutures, adhesive skin closures or glue. Although not as critical for keeping the wound closed, these external closures are important for the appearance of the healed wound. Careful application of whatever closure method is used will contribute to a smaller, flatter and less noticeable scar.
Adhesive Skin Closures
Adhesive skin closures (sometimes known by one of the trademark names such as 3M Steri-Strips) are applied in many cases for the final wound closure and are quite effective. They are designed to be left in place until they fall off naturally.
A few people develop blisters from the adhesive used on adhesive skin closures, but this problem is usually the result of improper application. The proper technique is to simply lay the strip over the wound and pat it into place. Sometimes the medical staff will stick one end down and apply traction (pull the strip tight) before sticking the other end down in the mistaken attempt to better close the wound. In reality, all this does is cause blistering of the skin similar to the photo to the left.
Glue Closure of Skin
Skin can also be closed with a special surgical glue called Dermabond (Cyanoacrylate). This is a favorite with patients since it is a “one and done” process – no removal required and no chance for pain.
Zip Surgical Skin Closure System
A relatively new type of wound closure is the non-invasive Zip Surgical Skin Closure which uses no stitches or staples. It is flexible and enables adjustable tension on the wound, which may improve the healing and scaring process.
It is applied with an adhesive, so care should be taken for patients who have sensitive skin. The Zip improves the patient experience by minimizing scarring and eliminating “railroad” marks that come with staples or sutures. It has some flexibility, so for many people it can be more comfortable when placed on a mobile joint like the knee. Patients can remove it at home since it peels off like a bandage. The wound is visible throughout the recovery process, enabling the care team and patient to easily monitor wound healing.