title: Video-assisted thoracoscopic surgery for correction of adolescent idiopatic scoliosis: comparison of 4.5 mm versus 5.5 mm rod constructs.
abstract: OBJECTIVE
  The purpose of this study is to report the comparative results of thoracoscopic correction achieved via cantilever technique using a 4.5 mm thin rod and the poly-axial reduction screw technique using a 5.5 mm thick rod in Lenke type 1 adolescent idiopathic scoliosis (AIS).
  
  
  METHODS
  Radiographic data, Scoliosis Research Society (SRS) patient-based outcome questionnaires, and operative records were reviewed for forty-nine patients undergoing surgical treatment of scoliosis. The study group was divided into a 4.5 mm thin rod group (n = 24) and a 5.5 mm thick rod group (n = 25). The radiographic parameters that were analyzed included coronal curve correction, the most caudal instrumented vertebra tilt angle correction, coronal balance, and thoracic kyphosis.
  
  
  RESULTS
  The major curve was corrected from 49.8 degrees and 47.2 degrees pre-operatively to 24.5 degrees and 18.8 degrees at the final follow-up for the thin and thick rod groups, respectively (50.8% vs. 60.2% correction). There were no significant differences between the two groups in terms of kyphosis, coronal balance, or tilt angle at the time of the final follow-up. The mean number of levels fused was 6.2 in the thin rod group, compared with 5.9 levels in the thick rod group. There were no major intraoperative complications in either group.
  
  
  CONCLUSIONS
  Significant correction loss was observed in the thin rod system at the final follow-up though both groups had comparable correction immediately post-operative. Therefore, the thick rod with poly axial screw system helps to maintain post-operative correction.
authors.affiliation: Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hak Sun
authors.initials: HS
authors.lastname: Kim
authors.forename: Jin Oh
authors.initials: JO
authors.lastname: Park
authors.forename: Ankur
authors.initials: A
authors.lastname: Nanda
authors.forename: Phillip Anthony
authors.initials: PA
authors.lastname: Kho
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Hwan Mo
authors.initials: HM
authors.lastname: Lee
authors.forename: Seong Hwan
authors.initials: SH
authors.lastname: Moon
authors.forename: Jung Won
authors.initials: JW
authors.lastname: Ha
authors.forename: Eun Kyoung
authors.initials: EK
authors.lastname: Ahn
authors.forename: Dong Eun
authors.initials: DE
authors.lastname: Shin
authors.forename: Sung Jun
authors.initials: SJ
authors.lastname: Kim
authors.forename: Eun Su
authors.initials: ES
authors.lastname: Moon
mesh_terms: D000293:Adolescent; D000328:Adult; D001863:Bone Screws; D005260:Female; D006801:Humans; D008297:Male; D011859:Radiography; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D020775:Thoracic Surgery, Video-Assisted / Q000379:methods*; D016896:Treatment Outcome