Reaserch On Corrective Surgery Program Of Pectus Excavatum Based On NUSS Procedure

Pectus excavatum is a kind of common congenital thorax deformity, incidence rate is 0.1%~0.3%, the main characteristic of it is the lower sternum, which the center is xiphoid, and the corresponding costal cartilage have being sunk back. If the situation is serious, the sunken sternum could depress the heart, reduce the lung capacity, even influence the patient's cardiopulmonary function. Meanwhile, the appearance of deformed thorax might cause the patient's inferiority complex and psychological damage.There are many kinds of surgical repair of pectus excavatum, including Nuss procedure, Ravitch procedure and sternal turnover operation. These kinds of surgical methods have their own advantages and characteristics, but the therapuetic effect of Nuss procedure is superior to two other surgical procedures, so that it becomes the most respected corrective surgery of pectus excavatum by doctors nowadays. In Nuss procedure, the sunken sternum and a part of costal cartilage are raised compulsorily, by inserting the corrective bar in patient's body, to achieve the purpose of correction of pectus excavatum. But the study about the change of mechanical enviorment of sternum and costal cartilage, which have been generated large deformation after Nuss procedure, is few. This topic simulates the Nuss procedure and studies the influence, which results from the change of mechanical enviorment of sternum and costal cartilage, to human's body, the related data are obtained which providing the referenced basis for Nuss procedure. At the same time, making the parametric study on Nuss procedure, it provides the possibility for proposing a more practical corrective surgery program of pectus excavatum.Objective Three-dimensional model of patient's thorax with pectus excavatum was constructed for biomechanical finite element analysis, providing referenced basis for Nuss procedure and presenting more feasible operation program.Methods Firstly, using the three-dimensional modeling function of software Geomagic Studio and Mimics, three-dimensional model of patient's thorax with pectus excavatum was established, including the collection of thorax image data, the generation of point cloud data and the establishment of three-dimensional thorax model. Then establishing the finite element model with 198964 elements and 332216 nodes by FE software ANSYS, and giving the model related material properties, the Nuss procedure has been simulated for biomechanical simulation analysis.Results and discussion This topic has reconstructed integrated three-dimensional finite element model of the patient's thorax with pectus excavatum, which reproduces complicated morphology of patient's thorax, including ribs, costal cartilage, sternums and thoracic vertebra, and presented a new method to establish the three-dimensional solid model separately by using software Mimics and Geomagic Studio together. Through the finite element methods, simulating the Nuss procedure for biomechnical analysis, the related numerical results about the change of mechnical enviorment of patient's thorax after Nuss procedure are obtained, which providing the referenced basis for Nuss procedure.Summarily, the model in this topic could reflect the biomechanical properties of the patient's thorax with pectus excavatum to some extent, and the related numerical results about the change of mechnical enviorment of patient's thorax after Nuss procedure are obtained.So it is a good foundation for further study of the corrective procedure of pectus excavatum and presenting the parametric surgery program.