title: Cervical compensatory alignment changes following correction of adult thoracic deformity: a multicenter experience in 57 patients with a 2-year follow-up.
abstract: OBJECT Alignment changes in the cervical spine that occur following surgical correction for thoracic deformity remain poorly understood. The purpose of this study was to evaluate such changes in a cohort of adults with thoracic deformity treated surgically. METHODS The authors conducted a multicenter retrospective analysis of consecutive patients with thoracic deformity. Inclusion criteria for this study were as follows: corrective osteotomy for thoracic deformity, upper-most instrumented vertebra (UIV) between T-1 and T-4, lower-most instrumented vertebra (LIV) at or above L-5 (LIV ≥ L-5) or at the ilium (LIV-ilium), and a minimum radiographic follow-up of 2 years. Sagittal radiographic parameters were assessed preoperatively as well as at 3 months and 2 years postoperatively, including the C-7 sagittal vertical axis (SVA), C2-7 cervical lordosis (CL), C2-7 SVA, T-1 slope (T1S), T1S minus CL (T1S-CL), T2-12 thoracic kyphosis (TK), apical TK, lumbar lordosis (LL), pelvic incidence (PI), PI-LL, pelvic tilt (PT), and sacral slope (SS). RESULTS Fifty-seven patients with a mean age of 49.1 ± 14.6 years met the study inclusion criteria. The preoperative prevalence of increased CL (CL > 15°) was 48.9%. Both 3-month and 2-year apical TK improved from baseline (p < 0.05, statistically significant). At the 2-year follow-up, only the C2-7 SVA increased significantly from baseline (p = 0.01), whereas LL decreased from baseline (p < 0.01). The prevalence of increased CL was 35.3% at 3 months and 47.8% at 2 years, which did not represent a significant change. Postoperative cervical alignment changes were not significantly different from preoperative values regardless of the LIV (LIV ≥ L-5 or LIV-ilium, p > 0.05 for both). In a subset of patients with a maximum TK ≥ 60° (35 patients) and 3-column osteotomy (38 patients), no significant postoperative cervical changes were seen. CONCLUSION Increased CL is common in adult spinal deformity patients with thoracic deformities and, unlike after lumbar corrective surgery, does not appear to normalize after thoracic corrective surgery. Cervical sagittal malalignment (C2-7 SVA) also increases postoperatively. Surgeons should be aware that spontaneous cervical alignment normalization might not occur following thoracic deformity correction.
authors: 1Department of Neurological Surgery, Northwestern University, Feinberg School of Medicine, Chicago, Illinois;
authors: Taemin
authors: T
authors: Oh
authors: 1Department of Neurological Surgery, Northwestern University, Feinberg School of Medicine, Chicago, Illinois;
authors: Justin K
authors: JK
authors: Scheer
authors: 2Scripps Clinic, San Diego;
authors: Robert
authors: R
authors: Eastlack
authors: 3Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia;
authors: Justin S
authors: JS
authors: Smith
authors: 4Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, New York;
authors: Virginie
authors: V
authors: Lafage
authors: 4Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, New York;
authors: Themistocles S
authors: TS
authors: Protopsaltis
authors: 5Department of Orthopaedic Surgery, University of California, Davis, Sacramento; 
authors: Eric
authors: E
authors: Klineberg
authors: 4Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, New York;
authors: Peter G
authors: PG
authors: Passias
authors: Departments of 6Orthopaedic Surgery and.
authors: Vedat
authors: V
authors: Deviren
authors: 7Department of Orthopaedic Surgery, Baylor Scoliosis Center, Plano, Texas; and.
authors: Richard
authors: R
authors: Hostin
authors: 5Department of Orthopaedic Surgery, University of California, Davis, Sacramento; 
authors: Munish
authors: M
authors: Gupta
authors: 8Rocky Mountain Hospital for Children, Denver, Colorado.
authors: Shay
authors: S
authors: Bess
authors: 4Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, New York;
authors: Frank
authors: F
authors: Schwab
authors: 3Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia;
authors: Christopher I
authors: CI
authors: Shaffrey
authors: 9Neurological Surgery, University of California, San Francisco, California;
authors: Christopher P
authors: CP
authors: Ames
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007738:Kyphosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods; D011183:Postoperative Complications / Q000209:etiology; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods; D013904:Thoracic Vertebrae / Q000601:surgery*; D055815:Young Adult
keywords: 3-column osteotomy; 3CO = 3-column osteotomy; ASD = adult spinal deformity; CL = cervical lordosis; LIV = lower-most instrumented vertebra; LL =lumbar lordosis; PI = pelvic incidence; PSO = pedicle subtraction osteotomy; PT = pelvic tilt; SPI = spinopelvic inclination; SS = sacral slope; SVA = sagittal vertical axis; T1S = T-1 slope; TK = thoracic kyphosis; UIV = uppermost instrumented vertebra; VCR = vertebral column resection; adult spinal deformity; cervical deformity; reciprocal change; sharp angular kyphosis; thoracic deformity