David L Skaggs1, Derek A Seehausen2, Kent T Yamaguchi2, Raymond J Hah2, Margaret L Wright3, David B Bumpass4, Han J Kim5, Lindsay M Andras2, Michael G Vitale3, Lawrence G Lenke4. 1. Children's Orthopaedic Center, Children's Hospital Los Angeles, 4650 Sunset Blvd, Los Angeles, CA 90027, USA. Electronic address: dskaggs@chla.usc.edu. 2. Children's Orthopaedic Center, Children's Hospital Los Angeles, 4650 Sunset Blvd, Los Angeles, CA 90027, USA. 3. Division of Pediatric Orthopaedic Surgery, Columbia University Medical Center, 630 West 168th St., New York, NY 10032, USA. 4. Orthopaedic Surgery, Washington University School of Medicine, 550 S. Euclid Ave, St. Louis, MO 63110, USA. 5. Department of Orthopaedic Surgery, Hospital for Special Surgery, 535 E 70th St., New York, NY 10021, USA.
Abstract
STUDY DESIGN: Multicenter, retrospective cohort study. OBJECTIVES: The purpose of this study is to determine how the amount of residual lowest instrumented vertebra (LIV) tilt correlates with radiographic measurements. SUMMARY OF BACKGROUND DATA: When performing a selective thoracic posterior spinal fusion for adolescent idiopathic scoliosis (AIS), the LIV may be tilted into the lumbar curve or made horizontal. METHODS: This is a multicenter retrospective study of 33 consecutive patients with AIS, Lenke types 1 to 4, lumbar modifier C, and a minimum follow-up of 2 years, who underwent selective thoracic posterior spinal fusions. Measurements obtained from pre- and postoperative radiographs were correlated with postoperative LIV tilt. RESULTS: At final follow-up, less postoperative LIV tilt significantly correlated with less thoracic apical translation (p = .023) when controlling for the position of the LIV relative to the stable vertebra and preoperative thoracic and lumbar curve flexibility. LIV tilt was not significantly associated with thoracic Cobb angle, lumbar Cobb angle, lumbar apical translation, coronal balance, sagittal balance, or the amount of correction obtained compared to their preoperative measurements (p > .05). CONCLUSION: Decreased LIV tilt was significantly associated with decreased thoracic apical translation. LIV tilt did not significantly correlate with coronal balance or any other radiographic measurement. We caution that these findings may only be applicable in C modifier curves and when the correct LIV is chosen. LEVEL OF EVIDENCE: Level III, Therapeutic study.
STUDY DESIGN: Multicenter, retrospective cohort study. OBJECTIVES: The purpose of this study is to determine how the amount of residual lowest instrumented vertebra (LIV) tilt correlates with radiographic measurements. SUMMARY OF BACKGROUND DATA: When performing a selective thoracic posterior spinal fusion for adolescent idiopathic scoliosis (AIS), the LIV may be tilted into the lumbar curve or made horizontal. METHODS: This is a multicenter retrospective study of 33 consecutive patients with AIS, Lenke types 1 to 4, lumbar modifier C, and a minimum follow-up of 2 years, who underwent selective thoracic posterior spinal fusions. Measurements obtained from pre- and postoperative radiographs were correlated with postoperative LIV tilt. RESULTS: At final follow-up, less postoperative LIV tilt significantly correlated with less thoracic apical translation (p = .023) when controlling for the position of the LIV relative to the stable vertebra and preoperative thoracic and lumbar curve flexibility. LIV tilt was not significantly associated with thoracic Cobb angle, lumbar Cobb angle, lumbar apical translation, coronal balance, sagittal balance, or the amount of correction obtained compared to their preoperative measurements (p > .05). CONCLUSION: Decreased LIV tilt was significantly associated with decreased thoracic apical translation. LIV tilt did not significantly correlate with coronal balance or any other radiographic measurement. We caution that these findings may only be applicable in C modifier curves and when the correct LIV is chosen. LEVEL OF EVIDENCE: Level III, Therapeutic study.