title: Three-dimensional analysis of 2 fusionless scoliosis treatments: a flexible ligament tether versus a rigid-shape memory alloy staple.
abstract: METHODS
  Experimental scoliosis was created and subsequently corrected in goats. The 3-dimensional (3-D) effects of the treatments were analyzed.
  
  
  OBJECTIVE
  To analyze the 3-D effect of 2 different fusionless scoliosis treatment techniques on an experimental idiopathic-type scoliosis using plain radiographs and computerized tomography.
  
  
  BACKGROUND
  Scoliosis is a complex 3-D spinal deformity with limited treatment options. By preserving growth, motion, and function of the spine, fusionless scoliosis surgery provides theoretical advantages over current forms of treatment.
  
  
  METHODS
  Scoliosis was created in 24 Spanish cross-X female goats using a flexible, left posterior asymmetric tether from the T5 to L1 laminae, with convex rib resection and concave rib tethering from T8 to T13. After 8 weeks of posterior tethering, goats were randomized into 3 treatment groups: group 1, no treatment; group 2, anterior-shape memory alloy staple; and group 3, anterior ligament tether with bone anchor. The 6 levels of maximal curvature were instrumented in groups 2 and 3. All goats were observed for an additional 12-16 weeks. Serial radiographs and computerized tomography were used to document progression/correction of coronal, sagittal, and transverse plane deformities throughout the study.
  
  
  RESULTS
  There were 20 goats that had progressive, structural, idiopathic-type, lordoscoliotic curves convex to the right in the thoracic spine over the 8-week tethering period. An overall deformity score equaling the sum of the scoliosis, lordosis, and axial rotation measurements was calculated for each goat at 3 times.
  
  
  CONCLUSIONS
  The data in this study show the ability of a ligament tether attached to a bone anchor to correct scoliosis modestly in the coronal plane, but not in the sagittal or transverse plane. In addition, although a significant decrease in the deformity score was shown initially in this group (P < 0.001), the effect was lost over time. The final deformity in the bone anchor/ligament tether group wassignificantly less than either the stapled or untreated groups (P < 0.03). Further study is warranted to provide a better understanding of the 3-D effects of fusionless scoliosis treatments.
authors.affiliation: Department of Orthopaedics, University of Utah, School of Medicine, Salt Lake City, USA. john.braun@hsc.utah.edu
authors.forename: John T
authors.initials: JT
authors.lastname: Braun
authors.forename: Ephraim
authors.initials: E
authors.lastname: Akyuz
authors.forename: Hunt
authors.initials: H
authors.lastname: Udall
authors.forename: James W
authors.initials: JW
authors.lastname: Ogilvie
authors.forename: Darrel S
authors.initials: DS
authors.lastname: Brodke
authors.forename: Kent N
authors.initials: KN
authors.lastname: Bachus
mesh_terms: D000497:Alloys / Q000627:therapeutic use; D000818:Animals; D001863:Bone Screws; D005260:Female; D006041:Goats; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016268:Internal Fixators; D009984:Orthopedic Fixation Devices; D011859:Radiography; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000601:surgery*
chemical_list: D000497:Alloys