Morphological Flattening And Analysis Of Three-dimensional Wound For Preoperative Flap Design

In recent years,high-energy injuries caused by serious traffic accidents,fires and industrial accidents have increased rapidly.It is estimated that there are nearly one million patients receiving wound repair surgery every year in China.Unreasonable preoperative design can easily lead to flap rupture and necrosis,which can lead to dysfunction of the affected area,and even amputation,adding more pain and economic burden to patients.Therefore,it is of great theoretical significance and practical value to study and innovate existing preoperative flap design methods and develop rational preoperative guidance schemes quickly,which is an excellent entry point for the translation of basic research into clinical applications.This paper is oriented to wound cases in clinc,in terms of the morphological flattening and analysis of three-dimensional wound.The study are listed as follows:Rapid topology reconstruction algorithm of wound model was studied,and the concept of hierarchical value was proposed.Based on hash table,the redundant data filtering algorithm of wound STL file was constructed to improve the filtering efficiency.The vertex-edge-face structure is used to realize the rapid topology reconstruction of wound model.On the basis of the complete description of the topological relationship information of wound surface,the definition of hierarchical value was proposed to further improve the structural relationship of wound surface and even surface model.Based on the Gauss curvature of discrete vertices,the developability analysis of mesh surface was realized;the generalized hierarchical value was supplemented.For the regular surface or the surface with good developability,K-means clustering method was introduced to further cluster the original surface hierarchy,which further reduces the iterative optimization time in the flattening process on the premise that the developed accuracy is not affected.Starting from the geometric morphology,explore the reasonable flattening method of special deformation in wound surface.This paper summarizes the advantages and disadvantages of geometric and mechanical methods in the process of wound surface flattening process,studies the commonness/dissimilarity of various forms of three-dimensional wound surfaces,and reveals the general applicability of seemingly disordered and irregular threedimensional wound surfaces.In view of the irregularity of the wound surface,the definition of deformation vertex is proposed for the first time from the point of view of the developability of discrete vertices,which distinguishes the mutation vertices and conventional surface points in the three-dimensional wound,solves them by classification and flattens them by classification.The principle of adjacent edge invariance was proposed to solve the problem of deformation in the process of deformation vertex flattening,and effectively reduce the cumulative error in the process of flattening.A three-dimensional wound surface morphological flattening and optimization algorithm based on hierarchical value is proposed.Based on the assumption of continuity and uniformity of material deformation,the initial flattening algorithm of three-dimensional wound is studied.On the basis of the initial flattening result of the wound surface,the optimization algorithm based on the improved mass-spring model is introduced to further improve the developed accuracy;the implicit Euler method is used to calculate the iterative position of the vertices in the mass-spring system,combined with the variable time step and the method of ignoring the initial velocity,which can effectively improve the stability of the algorithm.Based on the definition of the hierarchical value,by setting different elastic deformation coefficients on the discrete vertices of different levels in the wound suface,flattening layer by layer and optimizing layer by layer,the parallel optimization of the partial wound surface and the whole wound surface can be realized.Finally,the multi-resolution fairing method is applied to smooth the boundary contour of the wound flattening results,and the contour curve suitable for medical scene smoothing is obtained.The results show that the developed results obtained by this method can better fit the skin wound,and the average deviation of area and length after flattening is reduced to less than 10%.Development of three-dimensional wound morphological flattening system.Based on MFC and Open GL framework,a user-friendly interface program is constructed,which can import,display,flatten and analyze the three-dimensional wound model.It realizes the automatic output of preoperative flap design scheme,avoids a lot of manual operation and dependence on the operator’s skills and experience.It can also reduce the preparation time of preoperative design effectively,and it is of guiding significance to standardize the design process of preoperative flap design.