title: Rib-based Distraction Surgery Maintains Total Spine Growth.
abstract: BACKGROUND
  For children undergoing treatment of early onset scoliosis (EOS) using spine-based distraction, recently published research would suggest that total spine length (T1-S1) achieved after the initial lengthening procedure decreases with each subsequent lengthening. Our purpose was to evaluate the effect of rib-based distraction on spine growth in children with EOS.
  
  
  METHODS
  This was a retrospective multi-center review of 35 patients treated with rib-based distraction (minimum 5 y follow-up). Radiographs were analyzed at initial implantation and just before each subsequent lengthening. The primary outcome was T1-S1 height, which was also analyzed as: Change in T1-S1 height per lengthening procedure, percent of expected age-based T1-S1 growth per lengthening time interval, percent increase in T1-S1 height as compared with postimplantation total spine height, and percent of expected T1-S1 growth based upon patient age at time of lengthening procedure.
  
  
  RESULTS
  Thirty-five patients with a mean age of 2.6 years at initial surgery were studied. Diagnoses included congenital (n=18), syndromic (n=7), idiopathic (n=5), and neuromuscular (n=5). Major Cobb angle was 63.5 degrees and kyphosis was 40.5 degree. Four postoperative time periods were compared: L1 (preoperative first lengthening surgery), L2-L5 (preoperative second lengthening to preoperative fifth lengthening), L6-L10 (preoperative sixth lengthening to preoperative 10th lengthening), L11-L15 (preoperative 11th lengthening to preoperative 15th lengthening). Cobb angle stayed relatively constant for each lengthening period while maximum kyphosis increased. Total spine height was 19.9 cm pre-implantation, 22.1 cm postimplantation, and 28.0 cm by the 15th lengthening (P<0.05). Percent expected T1-S1 growth per lengthening was 62% for L2-L5, 95% for L6-L10, and 52% for L11-L15. As compared with postimplantation spine height, over the course of 15 lengthening procedures, a further 27% increase in spine height was observed. When lengthening procedures were performed when children were under age 5 years, 82% of expected growth was observed; between ages 6 and 10 years, 76% of expected growth was observed; and beyond age 10 years, 14% of expected growth was observed.
  
  
  CONCLUSIONS
  Patients treated with rib-based distraction surgery had an increase in total spine height from 20 cm preimplantation to 28 cm by the 15th lengthening. They maintained greater than 75% of expected age-matched spine growth until age 10 years and lengthening procedures did not appear to follow a law of diminishing returns. Rib-based distraction is an effective means of maintaining spine growth which is likely beneficial for pulmonary development as compared with the natural history of EOS.
  
  
  METHODS
  Level IV-Therapeutic study, case series.
authors.affiliation: *IWK Health Centre, Halifax, NS †Shriner's Hospital, Philadelphia, PA ‡Primary Children's Hospital, Salt Lake City, UT §Columbia Presbyterian Hospital New York, NY.
authors.forename: Ron
authors.initials: R
authors.lastname: El-Hawary
authors.forename: Amer
authors.initials: A
authors.lastname: Samdani
authors.forename: Jennie
authors.initials: J
authors.lastname: Wade
authors.forename: Melissa
authors.initials: M
authors.lastname: Smith
authors.forename: John A
authors.initials: JA
authors.lastname: Heflin
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Klatt
authors.forename: Michael G
authors.initials: MG
authors.lastname: Vitale
authors.forename: John T
authors.initials: JT
authors.lastname: Smith
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D019857:Osteogenesis, Distraction / Q000379:methods*; D011859:Radiography; D012189:Retrospective Studies; D012272:Ribs / Q000000981:diagnostic imaging / Q000601:surgery*; D012600:Scoliosis / Q000175:diagnosis / Q000601:surgery*; D013131:Spine / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000601:surgery; D016896:Treatment Outcome