QS4: In Vivo Quantitative Analysis of Subcutaneous Membranous Layers -Superficial And Deep Fascia- In Eleven Regions of the Human Body

PURPOSE: Surgical Site Infections (SSIs) and Hypertrophic scars (HSs) are the most common complications of wound healing. Most SSIs are superficial infections involving the skin and subcutaneous tissue (SQ) only. Abnormal scaring is driven by ongoing dermal inflammation in high skin tension areas (e.g. anterior and posterior chest). For prevention, proper suturing techniques are required, in particular for subcutaneous adipose tissue, to reduce high skin stretching tension and prevent ischemia. While adipose lobules cannot be sutured, superficial fascia (SF) -the membranous structure of adipose stroma- must be sutured. However, the exact anatomy and characteristics such as number and thickness of SF throughout the body regions are still lacking. This is the first study to present a detailed quantitative analysis of SF anatomy. We believe such details will help in optimization of subcutaneous sutures. METHODS: Superficial and deep fascia (DF) were analyzed using ultrasound imaging in predefined 73-point locations, distributed among eleven body regions of ten healthy male volunteers; Anterior chest: 9 points, abdomen: 10, posterior chest: 9, lumbar region: 6, gluteus: 2, arm: 8, elbow: 3, forearm: 8, thigh: 9, knee: 3 and leg: 6. Using ImageJ software, thickness of SF and DF layers, dermis and SQ were measured along SF percentage. Three random measurements were taken for each variable then averaged and used this average for statistical analysis. In addition, number of SF layers was counted, total thickness of SF was calculated by summing the average thickness of all SF layers and total membranous layers thickness by summing total SF and DF thicknesses. RESULTS: Overall, 730 means were analyzed with multilevel mixed linear model for all variables except average layer thickness of SF which had 1635 means; since each point had one or more layers of SF. DF and dermis were significantly thickest in posterior chest region which had the highest layer thickness of SF measuring 0.64 ± 0.01 mm. Anterior chest and gluteus had the highest content of SF due to having the highest layers number (3.67 ± 0.08, 3.45 ± 0.143), yet significantly thickest gluteus SQ and lowest SF percentage. SF changed inconsistently within subcutaneous adipose tissue; SF, DF and dermis jointly handles stretching tension, therefore, to understand the effect of environment, analysis of the variable’s interaction was performed and showed significant accelerated increase in the thickness of SF and dermis in anterior and posterior chest as compared to lower tension regions (all p<0.001). CONCLUSION: Our results showed that dermis and subcutaneous membranous layers tend to be thick in the high-tension areas such as the upper trunk. It was suggested that SSIs and HSs could be prevented by realizing the tension applied on the operated area; finding then suturing the membranous layers during the operation.