Biomechanieal effects of Nass procedure on thoracic wall of children with pectus excavatum

Abstract

Objective To evaluate the biomechanical effects of Nuss procedure on thoracic wall of children with pectus excavatum.Methods From 2004 to 2008,33 patients with pectus excavatum were followed up,who underwent Nuss procedure in this hospital.Ultrasonography and spiral CT were applied to evaluate the postoperative changes of ribs,costal cartilages,the first to the sixth costochondral ioints (CCJ),sternocostal joints (CSJ) and shape of chest walls.Resuits Nuss bar displacement was found in 2 cases.Postoperative bony thoracic protrusion was found in 4 (12.1%) patients.One patient got obsolete fracture on the fourth dexter rib near the costochondral junction,which was detected by ultrasonography at 3 years and 4 months after the operation.Traverse fracture on the fifth dexter rib was found in one case at one week postoperatively.Iniury on CSJ and CCJ was found in 8 cases (24.2%) shortly after the operation.Dropping of bilateral costochondral junction below the Nuss bar was found in 6 (18.2%) patients.Mottling ossification was found at the fifth sinister costal cartilage in 1 case.Conclusions Although the Nuss procedure has a great deal of advantages,it also brings some biomechanical damages to the chest wall The trauma on chest wall which is caused by external force of Nuss bar involves CCJ,CSJ,ribs and costal cartilage,which can cause separation or displacement of ESJ or EEJ,ossification of costal cartilage,fracture of the ribs and anisotropy of the thoracic wall. Key words: Pectus excavatum; Sternocostal Joint; Thoracic surgical procedures