How far should sutures be spaced?

In part 4 of the laceration evidence series, we learned that wound eversion is probably dogma. In part 5, we learned that sutures probably offer no real benefit over skin glue or steri-strips in the majority of our patients. However, if you do decide to suture a laceration, how far do you space your sutures? I am almost certain that no emergency physician has taken a scientific approach to this question. We just go by what we were taught, or use basic clinical judgment. But is there evidence to tell us how far futures should be spaced?

Based on my literature search, I don’t believe that this topic has been studied in emergency patients with traumatic wounds, so we will have to try to extrapolate from the surgical literature. 

In a study after Mohs microsurgery (meaning these are mostly elderly skin cancer patients), patients had half their wound closed with sutures every 2 mm and the other half with sutures every 5 mm. (Sklar 2019) They all had subcuticular sutures placed before the skin was closed. Based on a validated scar score, there was no difference between the groups at 3 months based on blinded assessments. My big problem with this study is that I think even 5 mm is still way too close. Aside from very complex repairs, I don’t think I ever place sutures closer than 1 cm, and usually they are further than that.

In another split-scar RCT in patients after excision of skin cancers in an outpatient clinic, suture spacing of 5 mm was compared to 10 mm. (Stoecker 2019) At 3 months, the appearance of the high density suturing was rated as significantly worse, although all differences were gone by 6 months. Complications were not different. (They claim a trend towards more complications in the high density side, based on a p value of 0.16, but this study is too small to really comment on complications.)

To space things out even further, another split-wound trial in 50 patients after Mohs microsurgery compared subcuticular sutures spaced at 1 cm and 2 cm. (Eshagh 2022) At 3 months, cosmesis was judged as the same by blinded assessors. There was no difference in complications. 

If this trend continued, with each study demonstrating equivalence of larger distances, we might eventually prove that sutures can be placed infinitely far apart. I guess, as mentioned in part 5 of this series, some studies have demonstrated that no sutures are just as good as sutures in carefully selected cuts. However, for now, these are the only 3 studies I was able to find on the topic. 

There was one more paper (published as a letter to the editor) looking at the perspectives of patients. Patients were shown images of wounds repaired with sutures placed at 2 mm, 4 mm, and 6 mm, and they judged the surgeon’s skill to be lowest in the 2 mm group. (Arshanapalli 2020) So if there is no difference in clinical outcomes, perhaps you should space out your sutures to improve your patient’s opinion of your skills. 

After spending a large amount of time reading literature about laceration repair, my theory is that our interventions have very little impact on outcomes. The skin is going to heal itself. We want to ensure the skin is clean and the edges of the wound are together, but how we accomplish that goal doesn’t really matter. This data seems to support that theory. So my final answer to the question, how far should my sutures be placed: only as close as they need to be to approximate the skin.

Personally, I tend to start towards the middle of the wound, and only place enough sutures so that the wound edges do not separate when the patients moves naturally.

References

Arshanapalli A, Tran JM, Aylward JL, Lasarev MR, Xu YG. The effect of suture spacing on patient perception of surgical skill. J Am Acad Dermatol. 2021 Mar;84(3):735-736. doi: 10.1016/j.jaad.2020.10.018. Epub 2020 Oct 16. PMID: 33075415

Eshagh K, Sklar LR, Pourang A, Armstrong AW, Dhaliwal H, Eisen DB. Interrupted subcuticular suture spacing during linear wound closures and the effect on wound cosmesis: a randomized evaluator-blinded split-wound comparative effectiveness trial. Br J Dermatol. 2022 Sep;187(3):318-323. doi: 10.1111/bjd.21625. Epub 2022 Jun 13. PMID: 35474448

Sklar LR, Pourang A, Armstrong AW, Dhaliwal SK, Sivamani RK, Eisen DB. Comparison of Running Cutaneous Suture Spacing During Linear Wound Closures and the Effect on Wound Cosmesis of the Face and Neck: A Randomized Clinical Trial. JAMA dermatology. 2019; 155(3):321-326. PMID: 30649154

Stoecker A, Blattner CM, Howerter S, Fancher W, Young J, Lear W. Effect of Simple Interrupted Suture Spacing on Aesthetic and Functional Outcomes of Skin Closures. J Cutan Med Surg. 2019 Nov/Dec;23(6):580-585. doi: 10.1177/1203475419861077. Epub 2019 Jul 4. PMID: 31272216