Understanding the Mechanical Forces on the Sacrum Can Help Optimize Flap-based Pilonidal Sinus Reconstruction

Area of Science:

• Biomedical Engineering
• Plastic Surgery
• Wound Healing

Background:

• Pilonidal sinus treatment often involves excision and flap reconstruction, but complications like wound dehiscence, infection, and recurrence are common.
• Understanding mechanical forces on the sacrococcygeal area during posture changes is crucial for optimizing flap selection in pilonidal sinus surgery.

Purpose of the Study:

• To quantify mechanical forces on the sacrum during sitting versus standing.
• To evaluate the suitability of the superior gluteal artery perforator (SGAP) flap for pilonidal sinus reconstruction based on these forces.

Main Methods:

• Measurements of skin-stretching, pressure, and shear stress on the sacrum were taken from sixteen volunteers comparing sitting and standing postures.
• Skin-stretching was assessed using a 4x4 cm square grid, while pressure and shear stress were measured at six sacral points.
• Retrospective review of ten pilonidal sinus cases treated with SGAP flaps was conducted to assess 6-month outcomes.

Main Results:

• Sitting significantly increases horizontal stretching tension (17.3%) and exerts high pressure (106.6 mm Hg) and shear stress (11.6 N) on the lower sacrum.
• The SGAP flap demonstrated optimal performance in releasing horizontal tension and mitigating pressure/shear stress due to its subcutaneous tissue and blood flow.
• The SGAP flap's donor site is located superior to the high-stress lower sacral region.

Conclusions:

• Sitting generates substantial mechanical forces on sacrococcygeal skin, contributing to pilonidal sinus surgery complications.
• The SGAP flap is a promising reconstructive option for large pilonidal sinus defects, potentially reducing complications by effectively managing mechanical forces.
• No complications were reported in the retrospective review of patients treated with SGAP flaps.