title: Progressive Changes in Sagittal Contour After Anterior Spinal Fusion With Instrumentation of Different Sizes for Thoracic Adolescent Idiopathic Scoliosis: Is Continued Posterior Spinal Growth an Issue in Skeletally Immature Children?
abstract: METHODS
  Retrospective analysis of radiographs for a prospective group of 196 adolescent patients with thoracic idiopathic scoliosis after anterior spinal fusion with instrumentation.
  
  
  OBJECTIVE
  To analyze progressive changes in the sagittal profile of immature and mature patients during the first 2 postoperative years.
  
  
  BACKGROUND
  In a previous study of similar patients, a flexible 3.2-mm rod construct was used. An additional 15° (average) of kyphosis was seen in 60% of Risser 0 patients. The current patient group had fusion with solid rod (>4.0-mm) instrumentation.
  
  
  METHODS
  All included patients had single anterior rod instrumentation, clinical and radiographic evidence of solid fusion, a minimum follow-up of 2 years, and a coronal progression of ≤5° including adequate biplanar standard radiographs at preoperative, immediate postoperative, and 2-year follow-up visits. Patients were stratified by skeletal maturity and preoperative thoracic kyphosis. Significant sagittal progression was defined as >10°.
  
  
  RESULTS
  Significant sagittal progression that caused the patient to be hyperkyphotic (T5-T12 > 40°) occurred in 18.37% of the 196 study patients. A total of 55 who were group I Risser 0 at the time of surgery and 141 were group II Risser 1-5. Progression occurred much more frequently in Risser 0 patients who had a preoperative T5-T12 of ≥30° (67.67%) versus Risser 1-5 patients (25.00%).
  
  
  CONCLUSIONS
  Compared with the authors' previous work, solid rod instrumentation (>4.0 mm) for anterior spinal fusion for thoracic scoliosis is better at preventing progressive thoracic kyphosis than the flexible rod (3.2 mm). However, when performing a thoracic anterior spinal instrumented fusion in skeletally immature patients when the preoperative T5-T12 sagittal curve is >30° it is recommended to leave a low normal kyphosis (20°) in the instrumented region of T5-T12.
authors.affiliation: Department of Orthopedic Surgery, SUNY Upstate Medical University, 6620 Fly Road, Suite 200, East Syracuse, NY 13057, USA. Electronic address: lavellew@upstate.edu.
authors.forename: William F
authors.initials: WF
authors.lastname: Lavelle
authors.affiliation: Brandywine Institute of Orthopaedics, 1561 Medical Dr, Pottstown, PA, USA.
authors.forename: Linda Park
authors.initials: LP
authors.lastname: D'Andrea
authors.affiliation: Department of Orthopedic Surgery, Cooper Bone and Joint Institute, Three Cooper Plaza Suite 403 Camden, New Jersey 08103, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Clements
authors.affiliation: Department of Orthopedic Surgery, The Institute for Spine and Scoliosis, 3551 N Broad St, Philadelphia, PA 19140, USA.
authors.forename: Randal R
authors.initials: RR
authors.lastname: Betz
keywords: Adolescent idiopathic scoliosis; Anterior spinal fusion; Instrumentation; Posterior spinal growth; Thoracic