TY - JOUR
T1 - Primary drivers of adult cervical deformity
T2 - Prevalence, variations in presentation, and effect of surgical treatment strategies on early postoperative alignment
AU - International Spine Study Group
AU - Passias, Peter G.
AU - Jalai, Cyrus M.
AU - Lafage, Virginie
AU - Lafage, Renaud
AU - Protopsaltis, Themistocles
AU - Ramchandran, Subaraman
AU - Horn, Samantha R.
AU - Poorman, Gregory W.
AU - Gupta, Munish
AU - Hart, Robert A.
AU - Deviren, Vedat
AU - Soroceanu, Alexandra
AU - Smith, Justin S.
AU - Schwab, Frank
AU - Shaffrey, Christopher I.
AU - Ames, Christopher P.
N1 - Publisher Copyright:
© 2017 by the Congress of Neurological Surgeons
PY - 2018/10/1
Y1 - 2018/10/1
N2 - BACKGROUND: Primary drivers (PDs) of adult cervical deformity (ACD) have not been described in relation to pre- and early postoperative alignment or degree of correction. OBJECTIVE: To define the PDs of ACD to understand the impact of driver region on global postoperative compensatory mechanisms. METHODS: Primary cervical deformity driver/vertebral apex level were determined: CS = cervical; CTJ = cervicothoracic junction; TH = thoracic; SP = spinopelvic. Patients were evaluated if surgery included PD apex, based on the lowest instrumented vertebra (LIV): CS: LIV ≤ C7, CTJ: LIV ≤ T3, TH: LIV ≤ T12. Cervical and thoracolumbar alignment was measured preoperatively and 3 mo (3M) postoperatively. PD groups were compared with analysis of variance/Pearson χ2, paired t-tests. RESULTS: Eighty-four ACD patients met inclusion criteria. Thoracic drivers (n = 26) showed greatest preoperative cervical and global malalignment against other PD: higher thoracic kyphosis, pelvic incidence-lumbar lordosis (PI-LL), T1 slope C2-T3 sagittal vertical axis (SVA), and C0-2 angle (P < .05). Differences in baseline-3M alignment changes were observed between surgical PD groups, in PI-LL, LL, T1 slope minus cervical lordosis (TS-CL), cervical SVA, C2-T3 SVA (P < .05). Main changes were between TH and CS driver groups: TH patients had greater PI-LL (4.47◦ vs −0.87◦, P = .049), TS-CL (−19.12◦ vs −4.30, P = .050), C2-C7 SVA (−18.12 vs −4.30 mm, P = .007), and C2-T3 SVA (−24.76 vs 8.50 mm, P = .002) baseline-3M correction. CTJ drivers trended toward greater LL correction compared to CS drivers (−6.00◦ vs 0.88◦, P = .050). Patients operated at CS driver level had a difference in the prevalence of 3M TS-CL modifier grades (0 = 35.7%, 1 = 0.0%, 2 = 13.3%, P = .030). There was a significant difference in 3M chin-brow vertical angle modifier grade distribution in TH drivers (0 = 0.0%, 1 = 35.9%, 2 = 14.3%, P = .049). CONCLUSION: Characterizing ACD patients by PD type reveals differences in pre- and postoperative alignment. Evaluating surgical alignment outcomes based on PD inclusion is important in understanding alignment goals for ACD correction.
AB - BACKGROUND: Primary drivers (PDs) of adult cervical deformity (ACD) have not been described in relation to pre- and early postoperative alignment or degree of correction. OBJECTIVE: To define the PDs of ACD to understand the impact of driver region on global postoperative compensatory mechanisms. METHODS: Primary cervical deformity driver/vertebral apex level were determined: CS = cervical; CTJ = cervicothoracic junction; TH = thoracic; SP = spinopelvic. Patients were evaluated if surgery included PD apex, based on the lowest instrumented vertebra (LIV): CS: LIV ≤ C7, CTJ: LIV ≤ T3, TH: LIV ≤ T12. Cervical and thoracolumbar alignment was measured preoperatively and 3 mo (3M) postoperatively. PD groups were compared with analysis of variance/Pearson χ2, paired t-tests. RESULTS: Eighty-four ACD patients met inclusion criteria. Thoracic drivers (n = 26) showed greatest preoperative cervical and global malalignment against other PD: higher thoracic kyphosis, pelvic incidence-lumbar lordosis (PI-LL), T1 slope C2-T3 sagittal vertical axis (SVA), and C0-2 angle (P < .05). Differences in baseline-3M alignment changes were observed between surgical PD groups, in PI-LL, LL, T1 slope minus cervical lordosis (TS-CL), cervical SVA, C2-T3 SVA (P < .05). Main changes were between TH and CS driver groups: TH patients had greater PI-LL (4.47◦ vs −0.87◦, P = .049), TS-CL (−19.12◦ vs −4.30, P = .050), C2-C7 SVA (−18.12 vs −4.30 mm, P = .007), and C2-T3 SVA (−24.76 vs 8.50 mm, P = .002) baseline-3M correction. CTJ drivers trended toward greater LL correction compared to CS drivers (−6.00◦ vs 0.88◦, P = .050). Patients operated at CS driver level had a difference in the prevalence of 3M TS-CL modifier grades (0 = 35.7%, 1 = 0.0%, 2 = 13.3%, P = .030). There was a significant difference in 3M chin-brow vertical angle modifier grade distribution in TH drivers (0 = 0.0%, 1 = 35.9%, 2 = 14.3%, P = .049). CONCLUSION: Characterizing ACD patients by PD type reveals differences in pre- and postoperative alignment. Evaluating surgical alignment outcomes based on PD inclusion is important in understanding alignment goals for ACD correction.
KW - Adult cervical deformity
KW - Cervical spine
KW - Cervicothoracic junction
KW - Compensatory mechanisms
KW - Postoperative alignment
KW - Primary driver
KW - Surgical correction
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U2 - 10.1093/neuros/nyx438
DO - 10.1093/neuros/nyx438
M3 - Article
C2 - 28950349
AN - SCOPUS:85044115839
SN - 0148-396X
VL - 83
SP - 651
EP - 659
JO - Clinical neurosurgery
JF - Clinical neurosurgery
IS - 4
ER -