title: Comparative analysis of pedicle screw versus hybrid instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis.
abstract: METHODS
  A retrospective matched cohort study.
  
  
  OBJECTIVE
  To comprehensively compare the 2-year postoperative results of posterior correction and fusion with segmental pedicle screw instrumentation versus with hybrid (proximal hooks and distal pedicle screws) constructs in adolescent idiopathic scoliosis (AIS) treated at a single institution.
  
  
  BACKGROUND
  Despite the reports of satisfactory correction and maintenance of scoliotic curves by pedicle screw instrumentation, there have been no reports on the comprehensive comparison of AIS treatment after segmental pedicle screw instrumentation versus hybrid instrumentation.
  
  
  METHODS
  A total of 58 AIS patients that underwent posterior fusion with hybrid instrumentation (29) or pedicle screw (29) instrumentation at a single institution were sorted and matched according to four criteria: similar patient age, fusion levels, identical Lenke curve type, and identical operative methods. Patients were compared at 2-year follow-up according to radiographic changes, operative time, intraoperative blood loss, pulmonary function tests, and SRS-24 outcome scores.
  
  
  RESULTS
  The two cohorts were well matched. The preoperative major Cobb angle averaged 62 degrees in the screw group and 60 degrees in the hybrid group. Average major curve correction was 70% in the screw group and 56% in the hybrid group (P = 0.001). At 2-year follow-up, major curve correction was 65% and 46%, respectively (P < 0.001). At 2-year follow-up, thoracic sagittal Cobb angle changes between T5 and T12 were 9.0 degrees decrease in the screw group and 2.4 degrees decrease in the hybrid group compared with preoperative (P = 0.024). There were no differences in the lowest instrumented vertebra below the lower end vertebra (P = 0.56), operative time (P = 0.14), and average estimated blood loss (P = 0.54). Two years following surgery, the screw group demonstrated improved percent predicted pulmonary function values compared with that of the hybrid group (FVC; 81% --> 81% in screw group vs. 85% --> 79% in hybrid group P = 0.08, FEV1; 73% --> 79% in screw group vs. 79% --> 75% in hybrid group, P = 0.006). Postoperative total SRS-24 scores were similar in both groups (hybrid group: 99 vs. screw group: 95) (P = 0.19). There were no neurologic complications related to hybrid or pedicle screw instrumentation.
  
  
  CONCLUSIONS
  Pedicle screw instrumentation offers a significantly better major curve correction and postoperative pulmonary function values without neurologic problems compared with hybrid constructs. Both instrumentation methods offer similar junctional change, lowest instrumented vertebra, operative time, and postoperative SRS-24 outcome scores in the operative treatment of AIS.
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, and Shriners Hospitals for Children, St. Louis, MO, USA.
authors.forename: Yongjung J
authors.initials: YJ
authors.lastname: Kim
authors.forename: Lawrence G
authors.initials: LG
authors.lastname: Lenke
authors.forename: Junghoon
authors.initials: J
authors.lastname: Kim
authors.forename: Keith H
authors.initials: KH
authors.lastname: Bridwell
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Cho
authors.forename: Gene
authors.initials: G
authors.lastname: Cheh
authors.forename: Brenda
authors.initials: B
authors.lastname: Sides
mesh_terms: D000293:Adolescent; D000328:Adult; D001863:Bone Screws; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D011446:Prospective Studies; D011859:Radiography; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery