ABSTRACT
Background: Pilonidal sinus can be treated with excision and flap reconstruction, but treatment is often complicated by wound dehiscence, infection, and recurrence. Understanding the mechanical forces on the sacrococcygeal area during posture change could help guide optimal flap choice. Methods: Sixteen volunteers underwent measurements of skin-stretching, pressure, and shear stress on the sacrum when sitting relative to standing. Skin-stretching was measured by drawing a 4 × 4 cm square on the sacrum and measuring the vertical, horizontal, and diagonal axes. Pressure and shear stress was measured at six sacral points with a device. The data analysis highlighted the potential of the superior gluteal artery perforator (SGAP) flap for dissipating mechanical forces. Ten pilonidal sinus cases treated with SGAP flaps were retrospectively reviewed for 6-month outcomes. Results: Sitting is associated with high stretching tension in the horizontal direction [estimated marginal mean (95% confidence intervals) = 17.3% (15.4%-22.6%)]. The lower sacrum experienced the highest pressure [106.6 (96.6-116.5) mm Hg] and shear stress [11.6 (9.7-13.5) N] during sitting. The transposed SGAP flap was deemed to be optimal for releasing the horizontal tension and providing sufficient subcutaneous tissue for ameliorating pressure/shear stress during sitting. It also has high blood flow and can therefore be used with large lesions. Moreover, its donor site is above the high-pressure/stress lower sacrum. Retrospective analysis showed that no patients experienced complications. Conclusions: Sitting is associated with high mechanical forces on the sacrococcygeal skin. The transposed SGAP flap may ameliorate these forces and thereby reduce the risk of complications of pilonidal sinus reconstruction for large defects.
ABSTRACT
BACKGROUND: Key risk factors for hypertrophic scarring and surgical-site infections are high-tension wounds, fat necrosis, and dead space. All could be prevented by appropriate superficial fascia suturing. However, the as-yet poorly researched anatomy of the superficial fascia should be delineated. This study is the first to quantify the superficial fascia throughout the human body in vivo. METHODS: Ultrasound was used to analyze the superficial and deep fascia of 10 volunteers at 73 points on 11 body regions, including the upper and lower trunk and limbs. Number, thickness and percentage of superficial fascia layers, and deep fascia and dermis thickness, were measured at each point. RESULTS: Seven hundred thirty ultrasound images were analyzed. Body regions varied markedly in terms of subcutaneous variables. Posterior chest had the thickest deep fascia and dermis and the highest average superficial fascia layer thickness [0.6 mm (95 percent CI, 0.6 to 0.7 mm)]. Anterior chest had the most superficial fascia layers [3.7 (95 percent CI, 3.5 to 3.8)]. Posterior and anterior chest had among the highest percentage of superficial fascia. Abdomen and especially gluteus had a low percentage of superficial fascia. Covariate analyses confirmed that posterior and anterior chest generally had higher superficial fascia content than gluteus and abdomen (both p < 0.001). They also showed that the dermis in the posterior and anterior chest increased proportionally to total fascia thickness. CONCLUSIONS: The superficial fascia, deep fascia, and dermis tend to be thick in high-tension areas such as the upper trunk. A site-specific surgical approach is recommended for subcutaneous sutures. CLINICAL RELEVANCE STATEMENT: Understanding the anatomical distribution of the superficial fascia and deep fascia will help surgeons optimize subcutaneous fasciae suturing, thereby potentially reducing the incidence of surgical-site infections and hypertrophic scars.
