Coronal T1 Pelvic Tilt, a Novel Predictive Index for Global Coronal Alignment in Adult Spinal Deformity

Abstract

Study Design. A retrospective radiographic study. Objectives. The aim of this study was to examine the association between global coronal alignment (GCA) and L4/L5 coronal tilt, and to verify the validity of our new index for evaluating GCA. Summary of Background Data. The mechanism of coronal imbalance is still unknown. The ability to level coronal tilts of L4 and L5 has been reported to impact the ability to achieve coronal balance, but the relationship between GCA and coronal tilt of L4 or L5 is unclear. On the contrary, although C7 migration is widely used for evaluating GCA, it has inherent defects as distance parameter. We focused on a novel global coronal angular parameter for evaluating the association of GCA with coronal tilt of L4 or L5. Methods. A total of 146 patients with adult spinal deformity were involved. The coronal measurements included C7 migration, fractional curve, L4 coronal tilt, L5 coronal tilt, major Cobb angle, and our novel global coronal parameter-coronal T1 pelvic tilt angle (CTPT, defined as the angle between a vertical line and the line connecting the middle point of S1 endplate to T1 centroid). We then determined the relationship between CTPT, C7 migration, and other coronal parameters. Results. C7 migration had significant correlation with L4 coronal tilt, L5 coronal tilt or fractional curve, but not with major Cobb angle. CTPT resembled C7 migration regarding its relationships with L4 coronal tilt, fractional curve, L5 coronal tilt and major Cobb angle. Regression analysis showed CTPT strongly associated with C7 migration (R 2 = 0.985), CTPT = 0.02+0.14∗ C7 migration and neither L4 coronal tilt nor L5 coronal tilt was an independent predictor of GCA. Conclusion. CTPT could be a practical index for evaluating GCA. Neither L4 coronal tilt nor L5 coronal tilt was an independent predictor of GCA. Level of Evidence: 3

The predictor for Preoperative Coronal Imbalance in patients with Degenerative Lumbar Scoliosis--A related analysis on spinopelvic parameters

“…According to previous studies [8,11] , structure curve had no in uence on coronal imbalance in ASD patients. Comparisons in this current study revealed that although the degree of the main curvatures of patients in the two groups had no difference, the involving vertebras were less in patients with coronal imbalance (group A) than those with coronal balance (group B)(t=2.639, P=0.009).…”

“…The increasing imbalance on the coronal plane in patients with degenerative lumbar scoliosis (DLS) has become one of main underlying factor that leads them to abnormal appearance, functional decline, and back pain [17] . The distance between C7 plumb line (C7PL) and central sacral vertical line (CSVL), named coronal balance difference [5] , coronal balance distance [12] , global coronal malalignment [14] , and C7 migration [11] , has been used to re ect coronal alignment. In this current study, we de ned the global coronal parameter as coronal balance distance (CBD).…”

“…On coronal radiographs 8 parameters were measured: 1) major Cobb angle, de ned as the angle between the superior endplate of the most tilted vertebra cranially and the inferior endplate of the most tilted vertebra caudally (left scoliosis was recorded as negative [-], right scoliosis as positive[+]). 2) Lumbosacral fractional curve [11] , de ned as the angle between the superior endplate of L4 and the line formed by pedicles of S1(left fractional curve was recorded as negative [-], right fractional curve as positive[+]). 3) Coronal balance distance(CBD) was de ned as the horizontal distance between the C7PL and the center of the S1 on coronal plane, C7PL on the left side of CSVL was recorded as negative(-), right side as positive(+).…”

Coronal Alignment in Adult Spinal Deformity Surgery

“…Several prior reports have outlined predictors and risk factors for postoperative CM (Table 2). First, considerable evidence from prior reports identify a positive correlation between preoperative and postoperative CM 8,16,19. Preoperative-CVA correlated with postoperative-CVA in a series of 67 ASD patients ( P <0.001)19 and a series of 121 ASD patients ( P <0.0001) 8.…”

“…The CTPT was positively correlated with CVA (termed C7 migration), with an R 2 value 0.985. 16 The authors emphasized the potential advantages of the CTPT (angle), compared with the CVA (distance), as no calibration is needed and it is not subject to body habitus variability. Lastly, additional reports have used less common composite outcomes to measure CM including T1 takeoff angle (T1-TO), shoulder tilt, and pelvic obliquity.…”