Predictive Model for Cervical Alignment and Malalignment Following Surgical Correction of Adult Spinal Deformity.
METHODS
Retrospective review of prospective multicenter database.


OBJECTIVE
Use predictive modeling to identify patient characteristics, radiographic, and surgical variables that predict reaching an outcome threshold of suboptimal cervical alignment after adult spinal deformity (ASD) surgery.


BACKGROUND
Cervical deformity (CD) after ASD correction has been defined with the following criteria: T1S-CL>20°, C2-C7 SVA>40 mm, and/or C2-C7 kyphosis >10°. While studies have analyzed CD predictors, few have defined and identified predictors of optimal cervical alignment after thoracolumbar surgery.


METHODS
Inclusion criteria were surgical ASD patients with baseline and 2-year follow-up. Postoperative cervical alignment (CA) and malalignment (nonCA) at 2 years was defined with the following radiographic criteria: 0°≤T1S-CL≤20°, 0 mm≤C2-C7 SVA≤40 mm, or C2-C7 lordosis >0°. Three thresholds classifying malalignment were defined: (T1) missing 1 criterion, (T2) missing 2 criteria, (T3) missing 3 criteria. Multivariable logistic stepwise regression models with bootstrap resampling procedure were performed for demographic, surgical, and radiographic variables. The model was validated with receiver operative characteristic and area under the curve.


RESULTS
Two hundred twenty-five surgical ASD patients were included. At 2 years 208 patients (92.4%) were grouped as CA in T3, while 17 (7.6%) were nonCA. Patients were similar in age (CA: 56.10 vs. nonCA: 55.78 years, P = 0.150), BMI (CA: 26.93 vs. nonCA: 26.94 kg/m, P = 0.716), and sex (CA: 76.5% vs. nonCA: 87.0%, P = 0.194). The final predictive model included C2 slope, C2-T3 CL, T1S-CL, C2-C7 CL, Pelvic Tilt, C2-S1 SVA, PI-LL, and Smith-Peterson osteotomies number. In this model (area under the curve 89.22% [97.49-80.96%]), the following variables were identified as predictors of nonCA: increased Smith-Peterson osteotomies use (OR: 1.336, P = 0.017), and C2-T3 angle (OR: 1.048, P = 0.005).


CONCLUSIONS
This study created a statistical model that predicts poor 2-year postoperative cervical malalignment in ASD patients. T3 (patients not meeting all three alignment criteria) was the most effective threshold for modeling nonCA, and included increased baseline C2-T3 angle and increased Smith-Peterson osteotomies during index.


METHODS
3.
Department of Orthopaedic Surgery, New York University Hospital for Joint Diseases, New York, NY.
Peter G
PG
Passias
Department of Orthopaedic Surgery, New York University Hospital for Joint Diseases, New York, NY.
Cheongeun
C
Oh
Department of Orthopaedic Surgery, New York University Hospital for Joint Diseases, New York, NY.
Cyrus M
CM
Jalai
Department of Orthopaedic Surgery, New York University Hospital for Joint Diseases, New York, NY.
Nancy
N
Worley
Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, NY.
Renaud
R
Lafage
University of San Diego, School of Medicine, San Diego, CA.
Justin K
JK
Scheer
Department of Orthopaedic Surgery, University of California, Davis, Sacramento, CA.
Eric O
EO
Klineberg
Department of Orthopaedic Surgery, Oregon Health and Science University, Portland, OR.
Robert A
RA
Hart
Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, NY.
Han Jo
HJ
Kim
Department of Neurosurgery, University of Virginia Medical Center, Charlottesville, VA.
Justin S
JS
Smith
Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, NY.
Virginie
V
Lafage
Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA.
Christopher P
CP
Ames
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D016208:Databases, Factual; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000601:surgery*; D008141:Lordosis / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010027:Osteotomy / Q000379:methods*; D011446:Prospective Studies; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult