Pectus Excavatum Nuss Orthopedic finite element simulation

Nuss Orthopedic of Pectus Excavatum(PE) is a novel minimal invasive surgical technique for the treatment of PE, however, the surgery will fail as the Nuss bar is slipped or rotated. In this paper, the preoperative and postoperative helical CT scans were carried out for one child patient of PE, and the preoperative and postoperative 3D model for thorax is built according to the CT. To preoperative thorax model of PE, the Nuss orthopedic process is simulated with finite element method, and a compare made between the simulated results and the postoperative model. The results show as the depressed sternum was jacking to normal position gradually by Nuss bar, the sternum, the ribs and the rib cartilages will all move upward which make the Nuss bar support the sternum at the location lower about 1∼6 mm than the end of depressed sternum end. However, original plan is that the bar should be supported just at the end of depressed sternum. After the bar is fixed, there is a torque on the bar for the pressure imposed by sternum and the force produced by the fixed place of bar forms a pair of torque. This torque may be the reason for the failure of surgery. The improvement is that the fix place of bar should be move upward 1∼6mm or a distance of one rib.