Abstract
The Nuss procedure is one of the most widely used operation techniques for pectus excavatum (PE) patients. It attains the normal shape of the chest wall by lifting the patient’s chest wall with the Nuss bar. However, the Nuss bar is for the most part bent by a hand bender according to the patient’s chest wall, and this procedure causes various problems such as the failure of the operation and a decreased satisfaction of the surgeon and patient about the operation. To solve this problem, we proposed a method for deriving the optimal operation result by designing patient-specific Nuss bars through computer-aided design (CAD) and computer-aided manufacturing (CAM), and by performing auto bending based on the design. In other words, a three-dimensional chest wall model was generated using the computed tomography (CT) image of a pectus excavatum patient, and an operation scenario was selected considering the Nuss bar insertion point and the post-operative chest wall shape. Then, a design drawing of the Nuss bar that could produce the optimal operation result was derived from the operation scenario. Furthermore, after a computerized numerical control (CNC) bending machine for the Nuss bar bending was constructed, the Nuss bar prototype was manufactured based on the derived design drawing of the Nuss bar. The Nuss bar designed and manufactured with the proposed method has been found to improve the Haller index (HI) of the pectus excavatum patient by approximately 37% (3.14 before to 1.98 after operation). Moreover, the machining error in the manufacturing was within ±5% compared to the design drawing. The method proposed and verified in this study is expected to reduce the failure rate of the Nuss procedure and significantly improve the satisfaction of the surgeon and patient about the operation.
Highlights
Pectus excavatum is one of the most well-known chest wall deformities, in which the entire chest including the costal cartilage and sternum is depressed due to the overgrowth of the costal cartilage
The Silastic molding method is a minimally invasive surgery that is used for cosmetic effect, but this method cannot solve the problems of physical function. [3,4]
The machining accuracies of 60 prototypes in total were evaluated through measurement of dimensions
Summary
Pectus excavatum is one of the most well-known chest wall deformities, in which the entire chest including the costal cartilage and sternum is depressed due to the overgrowth of the costal cartilage. The exact cause of PE has not been accurately identified, and it affects about one in every 300 children worldwide For these patients, the PE operation is strongly recommended since the major organs in the chest such as the heart and lungs can be subjected to pressure, and problems such as the degradation of cardiopulmonary function, growth, and physical activities are likely to be caused by PE [1,2]. The Ravitch procedure and the sternal turnover operation, which are called open surgery, require a resection of all deformed costal cartilage. They can correct the chest wall effectively, but it has disadvantages such as a large operation range, a long operating time, and a less cosmetic effect. The Silastic molding method is a minimally invasive surgery that is used for cosmetic effect, but this method cannot solve the problems of physical function. [3,4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
