We are taught the value of everting our wound edges from Day 1 in our surgery rotation in medical school. But just how important is it? Why do we do it? And can we cause harm when we fail to do it?
Eversion
Eversion is an axiom that has lost its source tag. The theorized value of wound edge eversion is that as a wound heals, it naturally contracts. Thus, the act of eversion allows the final wound to lay flat, rather than further contracting from a flat plane to eventually become become depressed at the center (inverted).
Historically, though eversion is touted as important, no studies exist which directly assess its value. Rather, most studies focus on what suturing techniques to use to achieve the best eversion.
Fortunately, our good colleagues in the world of dermatology have recently focused some energy on revisiting this question. From their interest came this 2015 study:
Nuts & Bolts:
- Cosmetic outcomes at 3 and 6 months were compared using a planar (flat) or everted wound edge approximation approach.
- An interesting facet of study design: to avoid the confounder of “train-tracking” cutaneous stitch marks on cosmesis, the authors achieved eversion using buried dermal sutures only. Epidermal closure was performed using steri-strips.
- Surgical repair was performed by attendings, fellows, and residents (a confounder?).
- Post-repair care was standardized.
- Power analysis was performed to determine sample size needed and enrollment goal was met.
- The majority of patients were 60-year-old Caucasian males.
- Very few wounds (10%, or 5 patients) involved the face.
- No difference was noted using either a subjective assessment scale nor objective measurements of scar height, depth, and width.
The study cited above is certainly not definitive and has some external vailidity/generalizability issues (single center, enrolled mostly 60 year old white males, few facial wounds, and most importantly, these were not traumatic lacerations), but it may be the best study out there addressing the question in the modern literature.
The End of Eversion? Perhaps not.
This study did become a subject of back-and-forth commentary and some controversy in the same journal. This is perhaps a testament to its impact, in that it provoked discussion of best practice in a topic that was previously dogmatic. Dr. Trufant & Dr. Leach warn not to generalize the findings of these studies, especially to areas like the convex surfaces of forehead, nose and cheeks:
“The convexities and concavities that compromise the human face are objects of intense, if often unconscious, scrutiny. The introduction of a depressed scar, even if only on the order of fractions of a millimeter, is enough to capture light, and consequently, the eye.”
My friend Dr. Jonathan Kantor, a practicing Dermatologist and author of the text The Atlas of Suturing Techniques offers up a different perspective. As it turns out, eversion itself may not be the secret to a cosmetic wound closure. Rather, the ability to successfully evert when approximating soft tissue may actually just be a surrogate marker for something more important: the absence of tension from a wound, creating an optimal healing environment. As you’ll hear me say again and again throughout this site, tension is the enemy of cosmetic wound closure, and perhaps that has been the real key all along.
Avoid Inversion
Whether or not you believe that eversion of a wound matters, Dr. Trufant and Dr. Leach allude to an important point. Inversion of a wound is bad, (except in the rare case that it’s a desired effect) and it is an easy consequence of a novice or carelessly performed repair. Even a small amount of inversion at the time of closure begets more profound inversion as the wound matures.
(Read this post on the Perfect Simple Interrupted Suture to avoid making this error!)
My reasoning here is not based on any study, aside from my own study of landscapes and environments.
While subtle depressions capture light and become accentuated, small mounds do not and recede into the background.
The light from the sun casts shadows that are especially prominent in depressed or inverted areas. Notice your eyes are drawn to the slight crevice in the center of this picturesque landscape at dusk. Photograph taken by yours truly in San Pedro de Atacama, Chile.
the desert, it’s the recesses and valleys that catch most of the shadow and appear darker relative to the hills.
A scar is more than just collagen and connective tissue. A scar is about perception. It is an interplay of light and shadow, as perceived by the beholder. This noted, light casts dark shadows in valleys, but not on flat planes or even all that much on small hills.
The best way to avoid inversion of a wound is to strive for the opposite–in other words, make a conscious effort to evert the wound. This ultimately may be the practical reason why wound edge eversion remains an important standard in traumatic wound care.