Browsing by Author "Wang, Chao-Jan"

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Increase in intrathoracic volume in pectus excavatum patients after the Nuss procedure
(2010-02-01)
Chang, Pei-Yeh
;
Hsu, Zhen-Yu
;
Lai, Jin-Yao
;
Wang, Chao-Jan
;
Ching, Yu-Tai
In this study, we present finite element analysis models to calculate the increase in intrathoracic volume of pectus excavatum patients after the Nuss procedure. One virtue of our approach is that the measurement of the intrathoracic volume has no time difference and is not affected by postoperative pain, which cannot be achieved with a 2-year difference between pre- and postoperative pulmonary function testing or any other clinical method. The calculations show that the intrathoracic volume of pectus excavatum patients increased by approximately 2.72-8.88% after the Nuss procedure. The increment curve was patient-dependent, although the increment behavior was similar among the six patients examined. The curve of the increase became flat when the elevating force exceeded 80 N or the displacement of the lower sternal end exceeded 2.6 cm in half of our cases.
Preliminary analysis of the forces on the thoracic cage of patients with pectus excavatum after the Nuss procedure
(2008-08-01)
Chang, Pei Yeh
;
Hsu, Zhen-Yu
;
Chen, Da-Pan
;
Lai, Jin-Yao
;
Wang, Chao-Jan
Background. The Nuss procedure corrects pectus excavatum using a pre-bent bar that generates stress on the chest wall. To investigate the biomechanical effects after the Nuss procedure, we designed a three-dimensional finite element analysis model to analyze the distribution of stress and strain induced in the chest wall. Methods. Three patients with pectus excavatum aged 8, 7, and 7 years, were enrolled in this study. The greatest upward displacements of their sternums after the operation were measured from computed tomography images and chest X-ray films. Based on these displacements, we constructed three finite element analysis models for analyzing biomechanical changes in the thoracic cage after the Nuss procedure. Findings. The simulation results indicated that greatest strain occurred at the third through seventh cartilages, especially where they join the sternum and ribs. A high bilateral stress distribution was also found over the backs of the third to the seventh ribs near the vertebral column. Interpretation. The stress and strain induced by the Nuss procedure can be analyzed using our finite element analysis model. Although the stress and strain may have some influence on chest and spine development, a more detailed finite element analysis model is recommended for future study to improve the accuracy of our simulation results. (c) 2008 Elsevier Ltd. All rights reserved.