In the past 10 years, Nuss bar and traditional Nuss procedure have been used for correction of PE [9-11]. However, shortcoming of the bar and procedure was also found [12, 13]. For example, the steel bar needs to be shaped with special tools before the operation and it is usually hard to push the steel bar through the anterior sternum . Besides, it is often difficult for surgeons to fix the steel bar firmly just by steel wire and it usually took a long time to place or withdraw the bar . As a result, we invent the introducer-bar complex and modify the traditional procedure to achieve better result.
Compared with traditional Nuss bar, this novel introducer-bar complex has several advantages. Firstly, the new steel bar was produced before the operation and was connected to the introducer. Therefore, there is no need to bend the steel bar during the operation which may damage the bar and lead to potential recurrence of pectus excavatum. Secondly, the introducer-bar complex is installed or removed by pushing or pulling without flipping widely, which simplify the procedure and decreases intraoperative trauma. Thirdly, traditional steel bar was fixed only by steel wire in the previous procedure, however, new steel bar could also be fixed by screws because of the arrangement of screw holes which can be used to fix the steel plate with the help of screws and a locking piece. At last, new steel bar is mainly supported by the ribs instead of intercostal muscles in our procedure, which effectively relieve postoperative pain and reduce complications such as bar displacement caused by rupture of intercostal muscles. In our study, no rupture of intercostal muscles was found and all of the 1 cases of bar displacement after the correction were associated with fracture of ribs caused by violent collision during football game.
Due to the above reasons, it is easier and more convenient for surgeons to implant, fix and withdraw the bar. In our study, the time of bar implantation and the time of bar removal in the new procedure group were significantly shorter than those in the traditional procedure group. It was possible that the shortening of the operation time may be an important factor for less blood loss and rapid postoperative recovery. The hospital stay in the new procedure group was significantly shorter than that of the traditional procedure group. Nevertheless, the improvement of the new steel bar still followed the basic principles of bilateral incision, minimally invasive bar implantation, and sternal uplift, which might be an important reason for the non-statistical difference between the two groups in the length of incision, the cost, the postoperative Haller index and the postoperative surgical outcome.
Severe complication was not found in the new procedure group. Precious study illustrated that most postoperative wound infections should be treated conservatively by debridement after removing the fixation bar . However, it was not necessary to remove the steel bar reported in our study. Bar displacement was often caused by rupture of intercostal muscles in traditional Nuss procedure, which may also the important reason for recurrence . Nevertheless, no rupture of intercostal muscles was found in our study and that might because the bar was mainly supported by the ribs instead of intercostal muscles.
In our study, there were 4 recurrent PE and 7 PE patients with 2 steel bars in the new procedure group. A lot of experience was collected during operation for the PE patients above. Cardiac injury was the most severe complication for recurrent PE, as an intraoperative injury of the heart or a major blood vessel could lead to intraoperative or postoperative mortality . As a result, the thoracoscopy was used and if necessary, an electrocautery hook was also introduced to dissect pleural adhesion in thoracic cavity followed by a 5-mm-diameter thoracoscope through each side of the chest. Moreover, our experiences showed that posterior sternal adhesion was usually severe and often difficult to be found in recurrent PE. Therefore, we routinely made a small incision under the xiphoid process to separate the adhesion between the right atrium and sternum under the guidance of thoracoscopy. In our study, no heart damage occurred, although right atrium was reported to be damaged during the separation process in several previous studies [17, 18]. If one bar was not enough to give a good cosmetic correction, another 1-2 bars were implanted through the same or additional incisions in previous studies .In the new procedure group of our study, 7 patients were implanted the second bar to correct the deformity, and no patient was treated by the third bar. Our experiences show those with 2 bars correction were often tall and thin, indicating that cases with lower body mass index (BMI) might tend to need 2 or more bars. The second bar was often implanted at the second or the third intercostal space with smaller size (than the first bar）. We fixed steel bar with wires in the shape of an 8 and sutured the bar to the rib together with chest wall muscles so as to reduce the dislocation rate.
This study was limited by scale of the patients included. Further high-level clinical evidence is required to evaluate the long-term applicability and benefits of the use of introducer-bar complex.