A hyperelastic finite-element model of human skin for interactive real-time surgical simulation.

A finite-element (FE) model of human skin is proposed for future use in an interactive real-time surgical simulation to teach surgeons procedures, such as facial reconstruction using skin-flap repair. For this procedure, skin is cut into flaps that are stretched to cover openings in the face. Thus, the model must recreate the visual, haptic, and force feedback expected by the surgeon. To develop the FE model, a series of in vitro experiments were conducted on samples of human skin, subjected to uniaxial and planar tensile straining. Reduced polynomial hyperelastic (HE) materials were found to fit many of the samples' stress-strain data well. Finally, an explicit dynamic FE mesh was developed based on the fitted HE material models. A total Lagrangian formulation with the half-step central difference method was employed to integrate the dynamic equation of motion of the mesh. The mesh was integrated into two versions of a real-time skin simulator: a single-threaded version running on a computer's main central processing unit and a multithreaded version running on the computer's graphics card. The latter was achieved by exploiting recent advances in programmable graphics technology.