Mechanism of bar displacement and corresponding bar fixation techniques in minimally invasive repair of pectus excavatum

Abstract Purpose Bar displacement is a major complication in repair of pectus excavatum with the Nuss technique. Mechanisms of bar displacement have been elucidated by case-by-case analysis, and specific bar fixation techniques have been developed to deal with each mechanism. The efficacy of our bar fixation techniques is appraised. Methods Data from 725 consecutive patients between 1999 and 2006 who were repaired with our modifications to the Nuss procedure were retrospectively analyzed. Results The mechanism of bar displacement consisted of one or a combination of the following types: type 1, “bar flipping”—rotation of the bar along the axis of hinge; type 2, “lateral sliding”—horizontal slipping of the bar to one side in asymmetric pectus excavatum; and type 3, “hinge-point disruption”—a dorsal shift of the bar owing to tearing of the supporting intercostal musculature. Specific bar fixation techniques have been tailored to compensate for potential mechanisms of bar displacement according to pectus morphology: multipoint pericostal bar fixation (MPF) (n = 496) for type 1 displacement; incorporation of a stabilizer on the depressed side (n = 169) for type 2 displacement; and hinge point reinforcement and the crane technique (n = 122) for type 3 displacement. The bar displacement rate was decreased with our mechanism-based approach (4.6% before MPF vs 1.8% after MPF, P = .045). In addition, the major complication rates (6.8% before MPF vs 2.0% after MPF, P = .001) and reoperation rates (5.5% before MPF vs 1.6% after MPF, P = .019) decreased. Conclusions Mechanism-based bar fixation techniques, especially multipoint pericostal wire fixation, seems to be effective in preventing bar displacement following pectus excavatum repair.