Biomechanical substitution of performing a linear section in various topographoanatomic areas of the face and neck

One of the key parameters of trauma during maxillofacial surgery is the depth of soft tissue detachment from underlying structures. From a biomechanical point of view, tension-free suturing corresponds to a state in which the equivalent stresses in the suture area do not exceed 0.05-0.10 MPa, which ensures the preservation of adequate blood supply, optimal course of reparative processes and minimal risk of wound edge divergence. A biomechanical analysis of the stress-strain state of the skin soft tissues was performed on an elastic three-dimensional model using the well-known finite element analysis and modeling package FEMAP 10.2.0, designed for implementation in the Windows environment on a personal computer. A threedimensional model was developed for a clinical case of a 38-year-old patient with a straight-line incision length of 40 mm in the submental area with a maximum width of lateral opening of the incision edges of 2 mm and a thickness of soft skin tissue of 1 mm. The value of the skin tissue deformation modulus E=0.414 MPa and the maximum depth of skin soft tissue detachment of a linear incision hmax=14 mm fully correspond to the analytical calculations. The depth of the longitudinal extension of the skin soft tissue detachment beyond the incision pole is taken equal to half the amplitude of the incision edge displacement Lext=0.5W=0.5×2=1 mm. Thus, the overall dimensions of the skin soft tissue detachment zone in the lateral and longitudinal directions of the incision are 30 mm and 42 mm, respectively. Thus, the width and depth of mobilization of soft skin tissues are the main controllable geometric parameters that determine the biomechanical conditions of wound healing on the face. The parameters of longitudinal mobilization for linear incisions are justified: the zone of “release” beyond the poles of the wound should depend not on the depth of detachment, but on the width of the gaping defect. The optimized shape of the zone of detachment of soft skin tissues for linear incisions is elliptical with the obligatory longitudinal exit of detachment of soft skin tissues beyond the pole of the incision equal to half the amplitude of opening of the edges of the incision Lext=0.5W.