RT Journal Article
SR Electronic
T1 T1 Slope Minus Cervical Lordosis (TS-CL), the Cervical Answer to PI-LL, Defines Cervical Sagittal Deformity in Patients Undergoing Thoracolumbar Osteotomy
JF International Journal of Spine Surgery
JO Int J Spine Surg
FD International Society for the Advancement of Spine Surgery
SP 362
OP 370
DO 10.14444/5042
VO 12
IS 3
A1 PROTOPSALTIS, THEMISTOCLES
A1 TERRAN, JAMIE
A1 SOROCEANU, ALEX
A1 MOSES, MICHAEL J.
A1 BRONSARD, NICOLAS
A1 SMITH, JUSTIN
A1 KLINEBERG, ERIC
A1 MUNDIS, GREGORY
A1 KIM, HAN JO
A1 HOSTIN, RICHARD
A1 Hart, ROBERT
A1 SHAFFREY, CHRISTOPHER
A1 BESS, SHAY
A1 AMES, CHRISTOPHER
A1 SCHWAB, FRANK
A1 LAFAGE, VIRGINIE
A1 INTERNATIONAL SPINE STUDY GROUP
YR 2018
UL https://www.ijssurgery.com/content/12/3/362.abstract
AB Background: Cervical kyphosis and C2-C7 plumb line (CPL) are established descriptors of cervical sagittal deformity (CSD). Reciprocal changes in these parameters have been demonstrated in thoracolumbar deformity correction. The purpose of this study was to investigate the development of CSD, using T1 slope minus cervical lordosis (TS-CL) to define CSD and to correlate TS-CL and a novel global sagittal parameter, cervical-thoracic pelvic angle (CTPA), with CPL. Methods: A multicenter, retrospective analysis of patients with thoracolumbar deformity undergoing three-column osteotomy was performed. Preoperative and postoperative cervical parameters were investigated. Linear regression for postoperative values resulted in a CPL of 4 cm corresponding to a TS-CL threshold of 17°. Patients were classified based on postoperative TS-CL into uncompensated (TS-CL > 17°) or compensated cohorts (TS-CL < 17°); the two were compared using an unpaired t test. Logistic regression modeling was used to determine predictors of postoperative CSD. Results: A total of 223 patients with thoracolumbar deformity (mean age, 57.56 years) were identified. CTPA correlated with CPL (preoperative r = .85, postoperative r = .69). TS-CL correlated with CTPA (preoperative r = .52, postoperative r = .37) and CPL (preoperative r = .52; postoperative r = .37). CSD had greater preoperative CPL (P < .001) and CTPA (P < .001). The compensated cohort had a decrease in TS-CL (from 10.2 to 8.0) with sagittal vertical axis (SVA) correction, whereas the uncompensated had an increase in TS-CL (from 22.3 to 26.8) with all P < .001. Reciprocal change was demonstrated in the compensated group given that CL decreased with SVA correction (r = .39), but there was no such correlation in the uncompensated. Positive predictors of postoperative CSD included baseline TS-CL > 17° (P = .007), longer fusion (P = .033), and baseline CTPA (P = .029).Conclusions: TS-CL and CTPA correlated significantly with established sagittal balance measures. Whereas reciprocal change in cervical and thoracolumbar alignment was demonstrated in the compensated cohort, the uncompensated population had progression of their cervical deformities after three-column osteotomy.Clinical Relevance: The balance between TS-CL mirrors the relationship between pelvic incidence minus lumbar lordosis in defining deformities of their respective spinal regions.