General Session: Adult Spinal Deformity

Presented by: S. Horn - View Audio/Video Presentation (Members Only)


C. Jalai(1), P. Passias(1), R. Lafage(2), B. Diebo(3), J. Scheer(4), S. Ramchandran(1), G. Poorman(1), S. Horn(1), V. Lafage(2), J. Smith(5), V. Deviren(6), R. Hart(7), T. Protopsaltis(1), A. Daniels(8), E. Klineberg(9), C. Shaffrey(5), C. Ames(10), International Spine Study Group

(1) NYU Hospital for Joint Diseases, Orthopaedic Surgery, New York, NY, United States
(2) Hospital for Special Surgery, New York, NY, United States
(3) SUNY Downstate, Orthopaedic Surgery, Brooklyn, NY, United States
(4) University of Illinois at Chicago, Neurosurgery, Chicago, IL, United States
(5) University of Virginia Medical Center, Neurosurgery, Charlottesville, VA, United States
(6) University of California at San Francisco, Orthopaedic Surgery, San Francisco, CA, United States
(7) Oregon Health and Science University, Portland, OR, United States
(8) Warren Alpert School of Medicine, Orthopaedic Surgery, Providence, RI, United States
(9) University of California, Davis, Orthopaedic Surgery, Davis, CA, United States
(10) University of California at San Francisco, Neurological Surgery, San Francisco, CA, United States


Background: Reciprocal changes (RC) in spinal alignment adjacent to fusions for cervical spine deformity (CSD) correction are poorly understood, particularly in relation to deformity driver location and surgical strategies.

Purpose: This study quantifies RC following CSD surgical treatment based on the location of the primary cervical deformity driver (PD) type.

Study Design/Setting: Retrospective review of a prospective, multi-center database for CSD patients.

Patient Sample: The analyzed cohort consisted of 84 surgical CSD patients.

Outcome Measures: Prevalence and distribution of PD groups; post-operative radiographic cranial (Slopes of C2, C1, C0, C2-C0 angle, MGS) and thoracolumbar (TK, T1 Slope, LL, PI-LL) RC at 3M.

Methods: Inclusion criteria: surgical CSD patients ≥18 years with complete pre- and post-operative (3M) radiographs. PD type and apex level were determined: CS=cervical, CTJ=cervicothoracic junction, TH=thoracic, SP=spino-pelvic. Patients were further evaluated if the surgery included the PD based on the lowest instrumented vertebra (LIV): CS: LIV≤C7, CTJ: LIV≤T3, TH: LIV≤T12. Distribution of categorical variables across PD groups with assessed with ANOVA and Pearson χ2. Post-operative RC in unfused segments proximal to the UIV and LIV were compared in PD groups with paired t-tests.

Results: PD distributions among 84 CSD patients: CS=33 (40.2%), CTJ=12 (14.6%), TH=26 (31.7%), SP=11 (13.4%). The most frequent PD apex for by type was C5 (32.3%) for CS, C7-T1 (36.4%) for CTJ, T3 (11.5%) for TH, and T1 (33.3%) for SP. PD groups were similar in surgical approach and osteotomy type (p>0.05 all cases), but CS and TH drivers differed in levels fused (8.00 vs. 11.39, p=0.032). Surgical construct ranges for PD type were: CS=C2-T3, CTJ=C3-T6, TH=C3-T8, SP=C3-T5. CS had significantly higher UIV (p=0.05) and LIV (p=0.002) than TH. In CS patients with LIV≤C7 (n=15, 48.4%), RC were observed in TK (38.93° vs. 46.29°, p=0.004) and T1 Slope (20.23° vs. 27.15°, p=0.022) at 3M. If the surgery involved the CTJ driver (LIV ≥T3; n=7, 63.6%), patients had a reciprocal LL decrease (59.86° vs. 54.71°, p=0.039) at 3M. Patients fusions involving the TH driver (LIV ≥T12; n=20, 76.9%) experienced RC in PI-LL (-5.42° vs. -1.11°, p=0.018), LL (58.05° vs. 53.95°, p=0.017), and upper cranial parameters: C1 Slope (17.68° vs. 0.11°, p< 0.001), C2-0 Slope (46.72° vs. 37.28°, p=0.003), and MGS (-27.00° vs. -2.60°, p=0.010). Patients whose index surgery did not involve the PD level did not display improvements in 3M global and spino-pelvic alignment (p>0.05 all cases), though had lower C1 (3.00° vs. -10.28°, p=0.001) and C0 (1.73° vs. -10.28, p=0.001) slopes.

Conclusions: Primary drivers (PD) of cervical spine deformity (CSD) in this prospective database were mainly CS (40.2%) and TH (31.7%). Reciprocal changes (RC), mainly occurred in unfused segments proximal to the construct, in thoracolumbar alignment (TK, LL), when the PD is taken into account during CSD correction. Consideration for the PD in CSD surgery may be important in achieving optimal sagittal alignment, and highlights the importance of long-standing films in CSD cases. Levels of Evidence: III