Biomechanical properties of the superficial fascial system.

BACKGROUND Surgical repair of the superficial fascial system (SFS) has been claimed to both increase wound strength and enhance surgical outcome through anchoring of deeper tissues. OBJECTIVE The authors assessed the biomechanical properties of the SFS to determine whether repair of the SFS layer improved early and long-term postoperative wound strength. METHODS Four complementary studies were conducted to study the dermis and SFS junctional architecture and connective tissue content: gross dissection using a dehydrating agent (Pen-Fix; Richard-Allan Scientific, Kalamazoo, MI), a histologic study with hemotoxylin and eosin staining, soft tissue radiography, and immunofluorescence staining. Freshly excised human abdominal and lower back/buttock tissues underwent a midline incision, followed by repair using dermal sutures only (DRM), dermal sutures plus SFS sutures (DRM/SFS) or repair of the SFS only (SFS). Fresh swine abdominal tissues were similarly excised and repaired. Biomechanical tests were undertaken to compare the ex vivo human and swine tissues. Three types of closure-dermal sutures only (DRM), dermal sutures plus permanent 0-braided nylon suture in the SFS (DRM/SFS/N), and dermal sutures plus absorbable 0-vicryl suture in the SFS (DRM/SFS/V) were also tested in an in vivo swine model. RESULTS Immunofluorescence studies showed collagen and elastin content and ratios to be comparable in the dermis and SFS. In ex vivo studies of human abdominal and back tissues, cyclic creep did not vary significantly among the different types of repair. DRM/SFS repair had a significantly higher failure load than dermal repair alone in both human abdominal and back tissues. In the in vivo swine study, normal tissue had a significantly higher failure load than all repair groups. The wounds where SFS had been repaired in addition to dermis exhibited an increased tensile strength and, among these, the wounds closed with SFS repair with a nonabsorbable suture exhibited greater tensile strength compared to absorbable suture repair. However, no statistically significant difference was noted, due to the small sample size. CONCLUSIONS We have determined, using an ex vivo model, that repair of the SFS layer in addition to dermis repair significantly increases the initial biomechanical strength of wound repair. This has the potential to decrease early wound dehiscence. In our in vivo model, the use of a nonabsorbable suture to approximate the SFS demonstrated a trend toward increased long-term wound strength. We believe our studies provide scientific data documenting that SFS is a key contributory strength layer in the early postoperative period, and is likely to be a strength layer even in the later stages of wound healing.