Numerical Simulation To The Minimal Invasion Correction Of Pectus Excavatum With Scoliosis

Pectus excavatum is a congenital disease, whose symptom is corpora sterni sinks inward, leading the bottom of the forebreast funnel-shaped, causing heart oppressed, and affecting the function of the heart-lung of the patient. 30% patients are together with idiopathic scoliosis. It has been found in clinical that patients with scoliosis will improve whose sunken dysmorphia of anocelia and arch dysmorphia with scoliosis are at the same side, on the contrary, symptom of scoliosis will aggravate.Experimental method and numerical simulation method are adopted during correction process of studying pectus excavatum with scoliosis. At present, neither can we get the strain distribution of thorax by carrying out electrical experiment in human body nor can we get cadavers of pectus excavatum with scoliosis to conduct electrical experiment because of the ethical restriction. It becomes the main method to acquire displacement field, stress field and strain field by carrying out numerical simulation for minimally invasive correction process of pectus excavatum with scoliosis. In this paper, the purpose of carrying out numerical simulation for correcting pectus excavatum is to recognize minimally invasive mechanisation of pectus excavatum with scoliosis, and confirm factors that confirming pectus excavatum for scoliosis, providing reasonable theoretical foundation for NUSS operation, and providing reference for artificial thorax model and animal thorax correction experiment.A thorax model including sternum, rib and vertebra thoracalis of pectus excavatum with scoliosis was rebuilt by using Mimics, Geomagic studio, and PRO/E. The author developed modeling method of discus intervertebralis which could ensure discus intervertebralis bond with vertebra thoracalis well, solving difficult problems in building discus intervertebralis in Mimics software better.Minimally invasive correction process of pectus excavatum with scoliosis was simulated by software ANSYS and the effects of geometric nonlinearity were taken into account. In order to solve difficulty in testing and verifying numerical simulation by experiment, minimally invasive correction process of pectus excavatum with scoliosis was simulated by software ABAQUS, and computing results of the two methods were compared. Numerical simulations of two models that left out discus intervertebralis and considered discus intervertebralis were carried out respectively, and the impact of discus intervertebralis to correction process was analyzed.Numerical simulation results indicated that the sternum was raised, symptom of pectus excavatum improved obviously, and degree of scoliosis eased to some extent after correction, confirming that correcting pectus excavatum was helpful to improve scoliosis when sunken dysmorphia of anocelia and arch dysmorphia with scoliosis were at the same side. Computing result indicated that discus intervertebralis had function of absorbing spinal deformation.The operation plan designed by numerical computing result has been applied to clinical operation in military general hospital of Beijing PLA, and operation result indicated that improvement of symptom of pectus excavatum and degree of scoliosis of patient were consistent with predicted result of numerical simulation.The author proposed instructive suggestions of carrying out electrical experiment of artificial thorax model and animal thorax model based on displacement field, stress field, and strain field of thorax in numerical simulation.