A Technique to Prevent Bar Displacement in the Nuss Procedure

Abstract

Introduction: Bar displacement is a serious complication of the Nuss procedure, occurring in ~3%–7% of patients.1–3 Three types of displacement have been well described: lateral sliding, bar flipping, and posterior disruption.4 The use of bar stabilizers has become common practice in most centers,5 but additional techniques to prevent displacement have been described, which include suturing or wiring the pectus bar and stabilizers, as well as adding additional novel fixation devices.3,4,6–13 De Campos et. al have previously described more medial placement of bar stabilizers, but required new, redesigned stabilizers because of difficulty sliding traditional stabilizers medially over a curved bar.14,15 In this video, we propose a simple modification in bar placement and stabilization using traditional implants that avoids invasive additional steps or costly equipment, while safeguarding against all three mechanisms of bar displacement. Materials and Methods: The patient is positioned supine, and the bilateral pectus ridges are marked. A Nuss bar is chosen that extends ~3 cm beyond the pectus ridge on each side. Using the external bar bender, the Nuss bar is gently curved, leaving the ends of the bar that extend beyond the insertion and exit sites straight. Bilateral skin incisions are made, in approximately the anterior axillary line, extending medially toward the pectus ridge. A 5 mm trocar for the thoracoscope is inserted into the left chest in line with, and lateral to, the bar incision. The bar is inserted and flipped using a standard bar flipper. Penetrating clamps can be used as a handle on the ends of the bar. Stabilizers are placed on each end of the bar and slid medially, just lateral to the chest wall insertion/exit sites. In situ bar benders are used to complete the curvature of the ends of the Nuss bar, thus locking the stabilizers into position. At the time of Nuss bar removal, straightening the Nuss bar to slide off the stabilizers can be cumbersome. We find that bending the stabilizers, such that the central slot opens, is a simpler method of removal. This can be performed by clamping both ends and simply bending, as the thin central portion of the stabilizer is quite malleable. Results and Conclusions: This technique addresses all three mechanisms of Nuss bar displacement. Lateral sliding is prevented by locking the stabilizers in place with in situ bending just lateral to the chest exit site. The bar cannot slide laterally as the stabilizers abut the chest wall exit site on each side. No sutures are required, as the bar and stabilizers become a single unit when locked in place by the bar's curvature. Placing the stabilizers more medially positions them at the inflection point, where the ribs angle superiorly. Thus, the stabilizers straddle two ribs on the anterior chest and have a broader base of support, preventing bar flipping. Finally, placing the stabilizers more anterior allows them to directly counteract the posterior pressure on the bar from the sternum. Instead of relying on the intercostal musculature laterally, the ribs themselves serve to support the stabilizers and bar from posterior dislocation. We have used this technique consistently on all patients at our institution for the past 2 years, a total of 26 patients. There have been no bar displacements. In conclusion, we report a technical modification of pectus bar placement and stabilization, using no additional equipment, to minimize the risk of three common mechanisms of bar displacement. No competing financial interests exist. Runtime of video: 6 mins 6 secs Video abstract presented at the American Pediatric Surgery Association 2017 Annual Meeting, Hollywood, FL, May 6, 2017.