Background: Bar displacement is one of the most common and serious complications after the Nuss procedure. However, measurements of and factors affecting bar displacement have not been reported. The objectives of this study were to develop a decision model to guide surgeons considering repeat treatment and to estimate optimal cut-off values to determine whether reoperation to correct bar displacement is warranted.
Methods: From July 2011 to August 2013, ninety bars were inserted in 61 patients who underwent Nuss procedures for pectus excavatum. Group A did not need surgical intervention and Group B required reoperation for bar displacement. Bar position was measured as the distance from the posterior superior end of the sternal body to the upper border of the metal bar on lateral chest radiographs. The bar displacement index (BDI) was calculated using D0 - Dx / D0 x 100 (D0: bar position the day after surgery; Dx: minimal or maximal distance of bar position on the following postoperative days). The optimal cut-off values of BDI warranting reoperation were assessed on the basis of ROC curve analysis.
Results: Of the 61 patients, 32 had single bars inserted whereas 29 had parallel bars inserted. There was a significant difference in age (14.0 ± 7.5 vs. 23.3 ± 12.0, p = 0.0062), preoperative Haller index (HI) (4.0 ± 1.1 vs. 5.0 ± 1.0, p = 0.033), and postoperative HI (2.7 ± 0.4 vs. 3.2 ± 0.5 p = 0.006) between the two groups. The optimal cut-off value of BDI was 8.7.
Conclusions: We developed a BDI model for surgeons considering performing reoperation after Nuss procedure. The optimal cut-off value of BDI was 8.7. This model may help surgeons to decide objectively whether corrective surgery should be performed. The main factors affecting the relationship between bar displacement and reoperation were age and preoperative HI.