title: Fixation points within the main thoracic curve: does more instrumentation produce greater curve correction and improved results?
abstract: METHODS
  Prospective consecutive multicenter case series.
  
  
  OBJECTIVE
  To compare fixation type and amount to curve correction controlled for curve flexibility.
  
  
  BACKGROUND
  The enhanced spinal purchase from segmental fixation should increase the force implants can exert without failure. This study evaluates whether this translates into correction beyond that expected from preoperative bending radiographs in thoracic curves where maximum correction was feasible (1A, 1B, and nonselective 1C fusions).
  
  
  METHODS
  One hundred seventy-one Lenke type 1 curves (118 1A, 36 1B, 23 1C) with 2-year follow-up were evaluated for the number and type of fixation points within the main curves compared to the correction obtained on preoperative bend films. SRS scores were compared to the amount of correction.
  
  
  RESULTS
  The number of fixation points both within the curve (P = 0.01) and for each vertebral body (P = 0.002) was larger for curves with greater correction compared to the bend films than those with less correction. Overall absolute correction was best for all screw and screw and wire constructs, followed by hook and screw, and least with hooks. However, compared to the bend films, these differences were not significant (P = 0.132). For all groups, the SRS scores significantly improved (P < 0.001), and was slightly more notable for the all screw constructs than other instrumentation patterns (P = 0.023). However, there were no significant difference in this improvement between those correcting more and those correcting less than the bend films (P = 0.578).
  
  
  CONCLUSIONS
  Absolute curve correction improved most with all pedicle screw and screw and wire constructs, but, when compared to bending films, the number of fixation points is more important than fixation type for curve correction. Although SRS scores improved the most in those with all screw constructs, the significance of this improvement is uncertain, and the SRS scores did not relate to whether curve correction was more or less than the bend films.
authors.affiliation: Department of Orthopaedics, University of Rochester, NY 14642, USA. James_Sanders@urmc.rochester.edu
authors.forename: James O
authors.initials: JO
authors.lastname: Sanders
authors.forename: Mohammad
authors.initials: M
authors.lastname: Diab
authors.forename: Stephens B
authors.initials: SB
authors.lastname: Richards
authors.forename: Lawrence G
authors.initials: LG
authors.lastname: Lenke
authors.forename: Charles E
authors.initials: CE
authors.lastname: Johnston
authors.forename: John B
authors.initials: JB
authors.lastname: Emans
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Sucato
authors.forename: Mark A
authors.initials: MA
authors.lastname: Erickson
authors.forename: Keith H
authors.initials: KH
authors.lastname: Bridwell
authors.forename: Richard E
authors.initials: RE
authors.lastname: McCarthy
authors.forename: John F
authors.initials: JF
authors.lastname: Sarwark
authors.forename: John P
authors.initials: JP
authors.lastname: Dormans
mesh_terms: D000293:Adolescent; D001863:Bone Screws; D001864:Bone Wires; D016009:Chi-Square Distribution; D006801:Humans; D011446:Prospective Studies; D011859:Radiography; D020127:Recovery of Function; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D012720:Severity of Illness Index; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D014481:United States