Stud Health Technol Inform. 2012;176:232-7. Discordance in spinal and thoracic correction using powerful full screw constructs in idiopathic scoliotic Konstantinos Soultanis a , Theodoros B. Grivas b , Konstantinos A. Starantzis a , Nikolaos A. Stavropoulos a , Christos Markopoulos a , Panayotis Papagelopoulos a a) First Department of Orthopaedics, ATTIKON University Hospital, Athens Medical School, Chaidari GR 12462, Greece b) Orthopaedic and Trauma Department, Tzanio General Hospital of Piraeus, GR-185 36, Piraeus, Greece Abstract. The pre and postoperative rib-vertebra angles and Cobb angles in patients with idiopathic scoliosis pre and post operatively treated with full transpedicular screw constructs were compared. Eighteen patients had right thoracic curves while only two had a left curve. 7 curves were Lenke’s type 3C, 6 type 5C, 4 type 1A, 3 type 6C and one type 2A. Convex side showed larger RVAs compared to the concaved side. The rib vertebra angle decreased from T1 to T12. The rib vertebra angles pre operatively (left vs right) were significantly different in every single level apart from T1, T7, T8 and T9. Cobb angle significantly improved post - operatively (p=0.0001). The post-operative rib vertebra angle differences significantly differed at all levels (p>0.05), but not in the region spanning the thoracic apex (T6-T7-T8). The powerful full-screw instrumentation corrects the Cobb angle very satisfactorily, but only partially corrects the rib cage asymmetry as this is expressed by the rib vertebra angle differences pre and post operatively. The small or no effect on the stiff apical ribs (T6-T8) and the possible role of the related musculature need to be further evaluated and analyzed. Keywords. Idiopathic Scoliosis, pedicle screw, rib cage deformity, RVAs, RVAD. Introduction Idiopathic scoliosis (IS) is a three dimensional deformity of the trunk with detectable bony asymmetries and deformities not only of the spine - the central axis - but also of the rib cage and other parts of the body. The thorax, like any other part of the skeleton displays variations in dimensions and proportions [1]. The bony framework of the thorax changes so that the side to side width of the chest cavity exceeds the anteroposterior length while the ribs become structurally stronger as the child grows up [2-5]. Although not very well understood, the role of a possible trunk muscles imbalance and the resultant functional impairment is seminal in the pathogenesis of a deformity; a lesson learned from the paralytic-type scoliosis. The appraisal of thoracic function by structural methods in healthy and deformed individuals has included measurements of the rib cage on radiographs to estimate the lung volume [6,7,8] and of the segmental rib vertebral angles (RVAs) in correlation to the spinal deformity [1,9,10,11]. In this connection, apical RVA differences (RVADs) and RVAs were first used prognostically in children with infantile idiopathic scoliosis