A Biomechanical Analysis of Barbed and Monofilament Suture in an Ex Vivo Skin Closure Model

Mookerjee, Vikram

Goals/Purpose:

Previous studies have suggested that barbed suture may have equivalent tensile strength compared to traditional suture materials, but this has never been tested in skin closure using tissue from living human donors. The primary aim of the current study was to determine if barbed suture would withstand a comparable tensile load to failure compared to conventional skin closure methods in an ex vivo skin closure model. The secondary aim was to assess the difference in the time required to close the skin between closure methods.

Methods/Technique:

A power analysis was conducted and determined that 12 specimens per group (24 samples total) was necessary to detect a 30N difference in the mean load to failure with a power of 80% and alpha of 0.05. Skin specimens were obtained from adult patients 18 years of age or older undergoing panniculectomy, abdominoplasty, or other abdominal wall surgery at a single institution between April 2021 and September 2022. Skin was provided to the study team in a de-identified fashion; patient age, sex, and prior bariatric surgery status were separately recorded. Exclusion criteria included specimens smaller than the testing dimensions and the presence of a rash, scar, or other dermatologic lesion that could compromise the strength of the specimen.

The skin from each patient was cut into two identical 5 cm by 2.5 cm samples, such that each patient served as their own control. Each sample was sectioned along the horizontal midline into two identical halves which would later be sutured together. The sample width of 2.5 cm was selected to precisely match the 2.5 cm width of the tensiometer arms utilized for stress testing (Instron High Precision Soft Tissue Testing System, Model 5848, Instron Corporation, Norwood, MA). Therefore, it was ensured that the stress forces applied by the tensiometer would be equally distributed across all points along the length of each specimen.

For each patient, the samples were randomized to one of two skin closure methods: knotless or layered. The knotless closure, the technique under investigation, consisted of a running subcuticular with 3-0 unidirectional barbed suture, which is equivalent in diameter to a 3-0 monofilament suture (V-Loc™, Wound Closure Device, Medtronic, Minneapolis, Minnesota, USA), and skin glue. The layered closure consisted of three equally spaced interrupted deep dermal sutures every 1.25 cm with 3-0 poliglecaprone (Monocryl, Ethicon Inc., Raritan, New Jersey, USA) followed by a running subcuticular with 4-0 poliglecaprone and skin glue.

A single surgeon sutured the skin edges together with one assistant. Skin closure was timed. The sutured tissue specimens were clamped in a tensiometer using a side screw action tensile grip and placed under an initial tensile load of 0 N with an excursion rate of 40mm/min until the repair failed. The load to failure was measured in Newtons (N), and mode of failure was recorded.

All statistical analysis was performed in R (R Foundation for Statistical Computing, Vienna, Austria). P-values less than 0.05 were considered statistically significant. Shapiro-Wilk and Levene’s test were used to assess normality and homogeneity of variances, respectively, and these tests indicated that all data were normally distributed and had similar variances. The closure time and load to failure for each group were compared using t-tests.

Results/Complications:

24 samples from 12 patients were tested. Mean load to failure for the knotless closure (46.5 ± 22.2 N) was significantly lower than the layered closure (79.3 ± 39.1 N) (p=0.022). All techniques failed due to suture rupture. Closure time was significantly shorter for the knotless technique (2.2 ± 0.6 minutes) compared to layered closure (5.6 ± 0.5 minutes) (p < 0.001).

Conclusion:

Barbed sutures significantly reduced closure time but were weaker than layered closures. However, the maximum strength of the barbed suture greatly exceeded estimates of clinical tension in wound closure published in previous studies. Under the appropriate clinical conditions, barbed suture may be a viable option to reduce closure time and suture material.