Could pelvic parameters determine optimal postoperative thoracic kyphosis in Lenke type 1 AIS patients?

Abstract

BackgroundA proper restoration of sagittal alignment is essential in AIS patients, but few studies provided a formula to predict an optimal surgical thoracic kyphosis (TK) gain in adolescent idiopathic scoliosis (AIS) patients. A formula was recently proposed (LL = (PI+TK)/2 + 10) to predict the optimal lumbar lordosis (LL) in adult spinal deformity patients, which has not been validated in adolescents. The aim of this study is to establish a formula with TK and pelvic parameters in normal adolescents and predict an optimal TK with this formula pre- and post-operatively in Lenke 1 AIS patients.MethodsA total of 60 asymptomatic adolescents were used to validate the proposed formula. The subject was considered to match with the formula, if the difference between the virtual TK and the theoretical TK was less than 10°. Then regression analysis was performed to establish a new formula to predict TK in adolescents. The predictive efficiency of the new formula was also validated in 40 Lenke 1 AIS patients.ResultsOf the 60 asymptomatic adolescents, only 26 (43.33%) asymptomatic adolescents matched with the adjusted formula: TK = 2 × (LL-10)-PI. The paired t test revealed a significantly different theoretical TK (tTK) compared to the virtual TK (41.23 ± 18.29° vs. 24.80 ± 8.75°, P < 0.001). Multiple linear regression showed that TK had a relationship with LL, SS and age (R2 = 0.331): TK = − 0.785 × LL-0.843 × SS + 0.858 × age + 3.754. There were 27 (67.50%), 32 (80.00%) and 35 (87.50%) Lenke 1 AIS patients matched this formula preoperatively, postoperatively and at the last follow-up.ConclusionOur results revealed that the predictive formula for sagittal alignment for adults was not applicable in adolescents. This study established a new predictive formula for TK based on asymptomatic adolescents. In Lenke 1 AIS patients, post-op TK in 87.5% of patients matched the predictive value, indicating that the new formula can be considered as a reference when making a surgery strategy.

Surgical increase in thoracic kyphosis increases unfused lumbar lordosis in selective fusion for thoracic adolescent idiopathic scoliosis

“…Knowing the effect of surgical correction of kyphosis on LL, it is possible, in the other direction, to predict thoracic kyphosis as a function of PI and LL [23]. We propose to adapt LL to PI according to the relation LL = PI + 15° as we found in our series.…”

A Retrospective Study of Factors Associated with Restoration of Thoracic Kyphosis in 43 Patients with Adolescent Idiopathic Scoliosis with Lenke Type 1 Curvature

“…A study review by Matsumoto et al [ 38 ] found evidence for a correlation between the decrease of TK and a decrease of LL [ 38 ]. Another study exploring the relationship between them also clearly stated that the findings followed the expected outcomes, and it additionally revealed that TK was closely connected to age [ 39 ]. Similarly, clinical imaging data from 180 cases indicated that the TK angle is connected to age to a certain extent before entering adulthood [ 40 ].…”

Assessment of Sagittal Spinopelvic Alignment in Asymptomatic Chinese Juveniles and Adolescents: a Large Cohort Study and Comparative Meta-analysis

“…Our meta-analysis showed that PI and SS were signi cant larger in Caucasians populations than those in Chinese populations, while we did not nd signi cant differences in TK, LL and PT between these two groups (all P > 0.05, Table 4). PI: Pelvic incidence, the angle subtended by a perpendicular from the upper endplate of S1 and a line connecting the center of the femoral head to the center of the upper endplate of S1 PT: Pelvic tilt, the angle between the vertical and the line through the midpoint of the sacral plate to femoral heads axis SS: Sacrum slope, the angle between the horizontal and the sacral plate Meta-analysis of sagittal parameters in adolescents A total of 15 studies 4-7,9−18,21 reported the sagittal parameters in adolescents, among which 5 studies [4][5][6][7]9 were performed in Asian populations, and other 10 studies [10][11][12][13][14][15][16][17][18]21 were performed in Caucasian populations.…”

“…Many studies [4][5][6][7][9][10][11][12][13][14][15][16][17][18]21 have been performed to explore the normal values of sagittal parameters in healthy asymptomatic adolescents with various ethnicities; however, the sample size of these studies was relatively small. Furthermore, although sagittal parameters had been reported in previous studies 10,11 , these normal values could be only used in Canada populations rather than Chinese populations.…”

“…Assessments of normal mean values of sagittal parameters in juveniles and adolescents are the key to the restoration of sagittal alignment in correction surgery. However, although the normal mean values of sagittal parameters in juveniles and adolescents have been reported in many studies, the results were con icting [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] . In addition, it has been veri ed that sagittal spinopelvic parameters vary in various ethnicities.…”