Incisions do not simply sum.

Area of Science:

• Surgical technique
• Wound healing
• Biomechanical analysis

Background:

• Critics question minimally invasive surgery (MIS) morbidity, comparing summed trocar site lengths to open incisions.
• This comparison incorrectly assumes linear summation of tension with incision length.

Purpose of the Study:

• To mathematically model and compare wound tension in open versus minimally invasive surgical incisions.
• To challenge the assumption that total tension in MIS is equivalent to open procedures of similar incision length.

Main Methods:

• A mathematical model was used to analyze wound tension perpendicular to linear incisions.
• Tension was modeled as a function of incision length, with integration revealing tension proportional to the square of the length.
• Scenarios for procedures like Nissen fundoplication and appendectomy were compared.

Main Results:

• Total wound tension increases nonlinearly with incision length.
• Multiple smaller incisions result in less total tension than a single larger incision of equivalent total length.
• Open appendectomy generated 2.7 times more wound tension than laparoscopic appendectomy.

Conclusions:

• Conventional open incisions experience greater total tension than multiple MIS trocar sites of equal total length.
• This supports using smaller trocars or no-trocar techniques to minimize pain and scarring.
• Using two small trocars is preferable to one larger trocar for reduced morbidity.