title: Segmental vs non-segmental thoracic pedicle screws constructs in adolescent idiopathic scoliosis: is there any implant alloy effect?
abstract: The aim of this study is to understand how many anchor sites are necessary to obtain maximum posterior correction of idiopathic scoliotic curve and if the alloy of instrumentation, stainless steel or titanium, may have a role in the percent of scoliosis correction.
  
  
  
  We reviewed 143 consecutive patients, affected by AIS (Lenke 1-2), who underwent a posterior spinal fusion with pedicle screw-only instrumentation between 2002 and 2005. According to the implant density and alloy used we divided the cohort in four groups.
  
  
  
  All 143 patients were reviewed at an average follow-up of 7, 2 years, the overall final main thoracic curve correction averaged 61.4%, whereas the implant density within the major curve averaged 71%. A significant correlation was observed between final% MT correction and preoperative MT flexibility and implant density.
  
  
  
  When stainless steel instrumentation is used non-segmental pedicle screw constructs seem to be equally effective as segmental instrumentations in obtaining satisfactory results in patients with main thoracic AIS. When the implant alloy used is titanium one, an implant density of ≥60% should be guaranteed to achieve similar results.
authors.affiliation: Spine Deformity Department, Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy. mario.disilvestre@ior.it.
authors.forename: Mario
authors.initials: M
authors.lastname: Di Silvestre
authors.affiliation: Spine Deformity Department, Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Georgeous
authors.initials: G
authors.lastname: Bakaloudis
authors.affiliation: Spine Deformity Department, Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Ruosi
authors.affiliation: Spine Deformity Department, Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Valerio
authors.initials: V
authors.lastname: Pipola
authors.affiliation: Spine Deformity Department, Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Colella
authors.affiliation: Spine Deformity Department, Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Greggi
authors.affiliation: Spine Deformity Department, Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Ruffilli
authors.affiliation: Spine Deformity Department, Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Vommaro
mesh_terms: D000293:Adolescent; D000497:Alloys / Q000627:therapeutic use*; D006801:Humans; D065289:Pedicle Screws; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation / Q000706:statistics & numerical data; D013904:Thoracic Vertebrae / Q000601:surgery*
chemical_list: D000497:Alloys
keywords: Adolescent idiopathic scoliosis; Implant density; Posterior instrumented fusion only; Titanium vs stainless steel