Modeling the cutting edge geometry of scalpel blades

Abstract

Scalpel blades are commonly used in surgery to perform invasive medical procedures, yet there has been limited research on the geometry that makes up these cutting instruments. The goal of this article is to define scalpel blade geometry and examine the cutting forces and deflection between commonly used scalpel blades and phantom gel. The following study develops a generalized geometric model that describes the cutting edge geometry in terms of normal rake and inclination angle of any continuously differentiable scalpel cutting edge surface. The parameter of scalpel-tissue contact area is also examined. The geometry of commonly used scalpel blades (10, 11, 12, and 15) is compared to each other and their cutting force through phantom gel measured. It was found that blade 10 displayed the lowest average total steady-state cutting force of 0.52 N followed by blade 15, 11, and 12 with a cutting force of 1.17 N (125% higher than blade 10). Blade 10 also displayed the lowest normalized cutting force of 0.16 N/mm followed by blades 15, 12, and 11 with a force of 0.19 N/mm (17% higher than blade 10).