Eur Spine J DOI 10.1007/s00586-015-3868-3
ORIGINAL ARTICLE
Sagittal alignment of cervical spine in adult idiopathic scoliosis Bilal Aykac1 · Selim Ayhan1 · Selcen Yuksel2 · Umit Ozgur Guler1 · Ferran Pellise3 · Ahmet Alanay4 · Francisco Javier Sanchez Perez-Grueso5 · Emre Acaroglu1 · ESSG European Spine Study Group
Received: 14 July 2014 / Revised: 23 January 2015 / Accepted: 8 March 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Purpose Alignment of the cervical spine (CS) in adolescent idiopathic scoliosis (IS) as well as in asymptomatic adult populations has recently been studied and described as being less lordotic in the adolescent IS population. However, few studies have examined the sagittal alignment of the CS in adult IS or its association with other radiological variables and clinical relevance. The aim of this study is to analyse the sagittal alignment of CS in adult IS and its association with age, alignment of the thoracic, lumbar and global spinal column as well as health-related quality of life (HRQOL) parameters. Methods A retrospective review of prospectively collected data from a multicenter database was performed. Of 468 consecutive adult IS patients, 213 were included in the study; the remainder were excluded due to poor quality Xrays where the CS was not properly visible, or previous surgery. X-rays were measured for the following CS parameters: [Cranial base-C2 (C0–C2) lordosis, C2–C7 lordosis, thoracic (T1) slope, thoracic inlet angle (TIA) and odontoid (Od)-T1 offset using a measurement software]. These measurements were then evaluated for possible associations with patient age and with pre-existing
alignment parameters and HRQOL scores using Pearson correlation tests. Results The average and standard deviations for CS alignment parameters were 32.3° ± 10.2° for C0–C2; 5.7° ± 14.1° for C2–C7; 23.9° ± 11.3° for T1 slope, 70.5° ± 14.7° for TIA and 20.8° ± 16.5° for Od-T1 offset. CS alignment showed a significant (p \ 0.05) correlation with age, T kyphosis and several other sagittal alignment parameters such as sagittal vertical axis (SVA), global tilt and T1 sagittal tilt, but not with the HRQOL parameters. Conclusion The sagittal alignment of the CS in adult IS is less lordotic than the normal average while less kyphotic than that of IS of a younger age. It correlates with age, thoracic kyphosis and some global sagittal alignment parameters. These findings suggest that CS alignment is likely a component of the global sagittal alignment strongly affected by thoracic kyphosis, and most probably does not affect HRQOL by itself. Keywords Adult idiopathic scoliosis · Cervical spine · Cervical spine alignment · HRQOL · Global sagittal alignment
Introduction & Emre Acaroglu [email protected] 1
Ankara Spine Center, Iran Caddesi 45/2, Kavaklidere, Cankaya, Ankara 06700, Turkey
2
Department of Biostatistics, Yildirim Beyazit University, Ankara, Turkey
3
Hospital Universitari Vall d’Hebron, Barcelona, Spain
4
Acibadem Maslak Hospital, Istanbul, Turkey
5
Hospital Universitari La Paz, Madrid, Spain
Adult scoliosis defines a fairly heterogeneous group of patients ranging from the cases of idiopathic scoliosis (IS) treated in the third and fourth decades of their lives to patients with de-novo degenerative deformity presenting with spinal stenosis and functional limitations from their sixth decade on. This heterogeneity is well recognised and it is frequently assumed that the early cases, representing those rolling over from the teenage years, pose pretty much the problems as their counterparts treated earlier [1].
123
Eur Spine J
All anatomical regions of the entire spine are in strong relation with one another; as Blondel demonstrated in an asymptomatic volunteer population; pelvic incidence (PI), lumbar lordosis (LL), thoracic kyphosis (TK) and cervical lordosis (CL) are strictly correlated. CL also shows relation with sagittal vertical axis (SVA), pelvic tilt (PT) and T1slope and tends to increase with age [2–4]. On the other hand, in young IS patients, the cervical spine (CS) develops a straight-to-kyphotic posture that correlates with global sagittal alignment, is a part of cervico-thoracic sagittal deformity without disturbing the global balance [5]. As compared with the adolescents, the frontal deformity and also the ageing process make the adult spine and pelvis more prone to imbalance as well as decompensation [1]. Nevertheless, the influence of cervical sagittal alignment on or in global spinal alignment parameters in patients with untreated adult IS is still under debate. It is also well known that there is a strong correlation with global sagittal alignment parameters and clinical outcomes based on the studies of thoracic, lumbar and/or spinopelvic radiographic parameters [6, 7]. However, there are only few studies evaluating the effect of cervical Table 1 Descriptive statistics for continuous variables
Variables
sagittal alignment on health-related quality of life (HRQOL) scores. Villavicencio et al. [8] found better clinical outcomes by providing an appropriate or improved segmental sagittal alignment in patients receiving anterior cervical discectomy and fusion. Later, Tang et al. [9] demonstrated that disability of the neck increases with positive sagittal malalignment after posterior cervical fusion. The impact of cervical sagittal alignment parameters on HRQOL scores in patients with untreated adult IS is still unknown. In the current study, the authors hypothesised that the sagittal alignment of adult IS patients follows the same patterns as their younger counterparts as well as those with accentuated local kyphosis would be relatively more frequent. Further, in spite of these “abnormalities” in the sagittal alignment of the CS, the authors did not expect that patients with cervical kyphosis may exhibit worse HRQOL scores after correction for global spinal alignment (SVA and global tilt) and age, based on clinical observations. To address these hypotheses, a multicentre database was retrospectively reviewed to analyse the sagittal alignment of the cervical spine, as well as its effects on global sagittal n
Mean (SD)
Median (range)
Age (years)
212
42.39 (18.35)
37.96 (18.83 to 83.17)*
Global tilt (°)
200
15.79 (13.72)
13.00 (−11.00 to 68.00)*
Lordosis gap
191
5.93 (15.37)
4.42 (−31.22 to 47.26)*
Lordosis (top of L1–S1) (°)
210
−55.38 (16.89)
−56.50 (−88.00 to 42.00)*
Lordosis (top of T12–S1) (°)
211
−54.04 (17.68)
−56.00 (−89.00 to 44.00)*
Pelvic incidence (°)
201
54.75 (11.79)*
55.00 (29.00 to 95.00)
Pelvic tilt (°)
201
16.85 (10.22)
16.00 (−12.00 to 51.00)*
Sacral slope (°) Sagittal balance (mm)
208 207
37.72 (9.79)* −0.93 (42.30)
39.00 (0.00 to 64.00) −5.72 (−96.80 to 154.54)*
T1 sagittal tilt (°)
197
−4.45 (4.37)
−5.00 (−16.00 to 10.00)*
T2–T12 kyphosis (°)
208
38.82 (17.75)*
37.50 (2.00 to 93.00)
T2–T5 kyphosis (°)
202
9.88 (8.63)
T5–T12 kyphosis (°)
205
32.09 (18.41)*
T10–L2 kyphosis (°)
211
10.40 (15.28)
C0–C2 lordosis (°)
213
32.31 (10.17)*
C2–7 lordosis (°)
213
5.72 (14.07)*
T1 slope (°)
213
23.88 (11.26)*
9.00 (−19.00 to 41.00)* 30.00 (−16.00 to 88.00) 8.00 (−33.00 to 77.00)* 33.00 (−7.00 to 68.00) 6.00 (−33.00 to 49.00) 24.00 (−1.00 to 63.00)
Thoracic inlet angle (°)
213
70.45 (14.66)*
69.00 (12.00 to 115.00)
Odontoid SVA (mm)
213
20.76 (16.53)*
20.59 (−24.58 to 78.75)
Major curve cobb angle (°)
210
48.59 (19.54)*
47.5 (−89 to 114)
ODI score
189
24.98 (18.03)
20.00 (0.00 to 100)*
SF-36 MCS score
187
44.20 (9.74)*
44.47 (18.54 to 67.98)
SF-36 PCS score SRS-22 subtotal score
187 192
42.45 (8.31) 3.34 (0.67)*
44.37 (20.77 to 60.40)* 3.40 (1.21 to 4.75)
SD standard deviation, ° degree, mm millimeter * The value which the evaluation of descriptive statistics performed (preferred because of the distribution of the variable)
123
Eur Spine J
145
72.5
PT, sacral slope (SS), SVA, T1 sagittal tilt, T2–T12 kyphosis, T2–T5 kyphosis, T5–T12 kyphosis, and T10–L2 kyphosis) as well as HRQOL parameters [Oswestry Disability Index (ODI), SF-36 Mental Component Score (MCS), SF-36 Physical CS, SRS 22 subtotal] using Pearson correlation analysis. In addition, the CS alignment in these patients was further classified into four types [cervical non-kyphosis (CNK), cervical kyphosis (CK), cervical-middle-thoracic kyphosis (CMTK) and cervical-lower-thoracic kyphosis (CTLK)] as described by Yu and coworkers [5] in a population of adolescent idiopathic scoliosis, then compared for all the other parameters that were listed above.
29 26
14.5 13
Statistical analysis
Table 2 Descriptive statistics for categorical variables Variables
n
%
Gender Female Male
177
83.1
36
16.9
SRS-Schwab classification-coronal D
109
51.7
L
42
19.9
N
34
16.1
T
26
12.3
SRS-Schwab classification-sagittal, PI-LL 0 + ++
SRS-Schwab classification-sagittal, PT 0
129
64.2
+
50
24.9
++
22
10.9
SRS-Schwab classification-sagittal, SVA 0
166
80.2
+
35
16.9
6
2.9
++
alignment and HRQOL parameters, in patients with untreated adult idiopathic scoliosis.
Patients and methods A retrospective review of prospectively collected data from a multicentre database on adult spinal deformity was performed. The criteria to be included in this database were defined as a patient having any or any combination of thoracic kyphosis exceeding 60°, coronal deformity exceeding 20°, pelvic tilt exceeding 25° and sagittal vertical axis exceeding 50 mm. Of 468 consecutive adult IS patients with specific diagnosis of IS defined by the treating physician(s) at the time of entry, 213 were included in the study; the remainder were excluded due to poor quality X-rays on which the CS was not properly visible, or previous spinal surgery in order not to create a bias. Standing AP and lateral full spine X-rays were measured for the following CS parameters: Cranial baseC2 (C0–C2) lordosis, C2–C7 lordosis, T1-slope, thoracic inlet angle (TIA) and odontoid (Od)-T1 offset in accordance with the landmarks described by Ames and coworkers [10] using a measurement software (Surgimap measurement tool provided by SRS). These measurements were then evaluated for possible associations with patient age, pre-existing alignment parameters (Global Tilt [11], Lordosis Gap [12], lordosis L1–S1, lordosis T12–S1, PI,
In accordance with the shape of the data set of variables, mean and median values were given as descriptive statistics. Two group comparisons were handled by t test or Mann–Whitney U test statistics according to normality assumption implemented. Likewise, more than two group comparisons were processed by ANOVA or Kruskal– Wallis test statistics based on normality assumption. The relationships between categorical variables were evaluated by Chi-square test. Correlations between two continuous variables were analysed by Pearson correlation coefficient or Spearman’s correlation coefficient rendering assumption of normality. Type-I error rate was taken as α = 0.05 for statistical significance. SPSS 21.0 was used for statistical analyses [13].
Results The descriptive statistics of the continuous and categorical variables can be seen in Tables 1 and 2. Means and standard deviations for CS alignment parameters were 32.3° ± 10.2° for C0–C2; 5.7° ± 14.1° for C2–C7; 23.9° ± 11.3° for T1-slope, 70.5° ± 14.7° for TIA and 20.8° ± 16.5° for Od-T1 offset. Table 3 demonstrates the statistical evaluation and the relationships between the CS and clinical coefficients. The CS alignment parameters did not demonstrate a uniform pattern of correlation with age as well as the sagittal alignment parameters. Cranio-cervical lordosis angle was not found to be correlated with any parameter. Od-T1 offset was found to be correlated only with T1 sagittal tilt and parameters of LL and TK. Subaxial kyphosis, T1-slope and T1 inclination were found to be strongly correlated with age (in addition to the parameters that correlated with the Od-T1 offset). Based on this finding, all other correlation analyses were performed after normalisation of the data by age. Of interest, in general, the CS alignment parameters correlated neither with the
123
Eur Spine J Table 3 Correlation matrix between C0–C2, C2–7, T1Slope, TIA, Odontoid SVA variables and clinical coefficients
Variables
C0–C2
C2–7
T1-Slope
TIA
Odontoid SVA
Age Pearson correlation p value
−0.041
0.208*
0.209*
0.550
0.002
0.002
0.273**
0.334**
0.273**
ORIGINAL ARTICLE
Sagittal alignment of cervical spine in adult idiopathic scoliosis Bilal Aykac1 · Selim Ayhan1 · Selcen Yuksel2 · Umit Ozgur Guler1 · Ferran Pellise3 · Ahmet Alanay4 · Francisco Javier Sanchez Perez-Grueso5 · Emre Acaroglu1 · ESSG European Spine Study Group
Received: 14 July 2014 / Revised: 23 January 2015 / Accepted: 8 March 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Purpose Alignment of the cervical spine (CS) in adolescent idiopathic scoliosis (IS) as well as in asymptomatic adult populations has recently been studied and described as being less lordotic in the adolescent IS population. However, few studies have examined the sagittal alignment of the CS in adult IS or its association with other radiological variables and clinical relevance. The aim of this study is to analyse the sagittal alignment of CS in adult IS and its association with age, alignment of the thoracic, lumbar and global spinal column as well as health-related quality of life (HRQOL) parameters. Methods A retrospective review of prospectively collected data from a multicenter database was performed. Of 468 consecutive adult IS patients, 213 were included in the study; the remainder were excluded due to poor quality Xrays where the CS was not properly visible, or previous surgery. X-rays were measured for the following CS parameters: [Cranial base-C2 (C0–C2) lordosis, C2–C7 lordosis, thoracic (T1) slope, thoracic inlet angle (TIA) and odontoid (Od)-T1 offset using a measurement software]. These measurements were then evaluated for possible associations with patient age and with pre-existing
alignment parameters and HRQOL scores using Pearson correlation tests. Results The average and standard deviations for CS alignment parameters were 32.3° ± 10.2° for C0–C2; 5.7° ± 14.1° for C2–C7; 23.9° ± 11.3° for T1 slope, 70.5° ± 14.7° for TIA and 20.8° ± 16.5° for Od-T1 offset. CS alignment showed a significant (p \ 0.05) correlation with age, T kyphosis and several other sagittal alignment parameters such as sagittal vertical axis (SVA), global tilt and T1 sagittal tilt, but not with the HRQOL parameters. Conclusion The sagittal alignment of the CS in adult IS is less lordotic than the normal average while less kyphotic than that of IS of a younger age. It correlates with age, thoracic kyphosis and some global sagittal alignment parameters. These findings suggest that CS alignment is likely a component of the global sagittal alignment strongly affected by thoracic kyphosis, and most probably does not affect HRQOL by itself. Keywords Adult idiopathic scoliosis · Cervical spine · Cervical spine alignment · HRQOL · Global sagittal alignment
Introduction & Emre Acaroglu [email protected] 1
Ankara Spine Center, Iran Caddesi 45/2, Kavaklidere, Cankaya, Ankara 06700, Turkey
2
Department of Biostatistics, Yildirim Beyazit University, Ankara, Turkey
3
Hospital Universitari Vall d’Hebron, Barcelona, Spain
4
Acibadem Maslak Hospital, Istanbul, Turkey
5
Hospital Universitari La Paz, Madrid, Spain
Adult scoliosis defines a fairly heterogeneous group of patients ranging from the cases of idiopathic scoliosis (IS) treated in the third and fourth decades of their lives to patients with de-novo degenerative deformity presenting with spinal stenosis and functional limitations from their sixth decade on. This heterogeneity is well recognised and it is frequently assumed that the early cases, representing those rolling over from the teenage years, pose pretty much the problems as their counterparts treated earlier [1].
123
Eur Spine J
All anatomical regions of the entire spine are in strong relation with one another; as Blondel demonstrated in an asymptomatic volunteer population; pelvic incidence (PI), lumbar lordosis (LL), thoracic kyphosis (TK) and cervical lordosis (CL) are strictly correlated. CL also shows relation with sagittal vertical axis (SVA), pelvic tilt (PT) and T1slope and tends to increase with age [2–4]. On the other hand, in young IS patients, the cervical spine (CS) develops a straight-to-kyphotic posture that correlates with global sagittal alignment, is a part of cervico-thoracic sagittal deformity without disturbing the global balance [5]. As compared with the adolescents, the frontal deformity and also the ageing process make the adult spine and pelvis more prone to imbalance as well as decompensation [1]. Nevertheless, the influence of cervical sagittal alignment on or in global spinal alignment parameters in patients with untreated adult IS is still under debate. It is also well known that there is a strong correlation with global sagittal alignment parameters and clinical outcomes based on the studies of thoracic, lumbar and/or spinopelvic radiographic parameters [6, 7]. However, there are only few studies evaluating the effect of cervical Table 1 Descriptive statistics for continuous variables
Variables
sagittal alignment on health-related quality of life (HRQOL) scores. Villavicencio et al. [8] found better clinical outcomes by providing an appropriate or improved segmental sagittal alignment in patients receiving anterior cervical discectomy and fusion. Later, Tang et al. [9] demonstrated that disability of the neck increases with positive sagittal malalignment after posterior cervical fusion. The impact of cervical sagittal alignment parameters on HRQOL scores in patients with untreated adult IS is still unknown. In the current study, the authors hypothesised that the sagittal alignment of adult IS patients follows the same patterns as their younger counterparts as well as those with accentuated local kyphosis would be relatively more frequent. Further, in spite of these “abnormalities” in the sagittal alignment of the CS, the authors did not expect that patients with cervical kyphosis may exhibit worse HRQOL scores after correction for global spinal alignment (SVA and global tilt) and age, based on clinical observations. To address these hypotheses, a multicentre database was retrospectively reviewed to analyse the sagittal alignment of the cervical spine, as well as its effects on global sagittal n
Mean (SD)
Median (range)
Age (years)
212
42.39 (18.35)
37.96 (18.83 to 83.17)*
Global tilt (°)
200
15.79 (13.72)
13.00 (−11.00 to 68.00)*
Lordosis gap
191
5.93 (15.37)
4.42 (−31.22 to 47.26)*
Lordosis (top of L1–S1) (°)
210
−55.38 (16.89)
−56.50 (−88.00 to 42.00)*
Lordosis (top of T12–S1) (°)
211
−54.04 (17.68)
−56.00 (−89.00 to 44.00)*
Pelvic incidence (°)
201
54.75 (11.79)*
55.00 (29.00 to 95.00)
Pelvic tilt (°)
201
16.85 (10.22)
16.00 (−12.00 to 51.00)*
Sacral slope (°) Sagittal balance (mm)
208 207
37.72 (9.79)* −0.93 (42.30)
39.00 (0.00 to 64.00) −5.72 (−96.80 to 154.54)*
T1 sagittal tilt (°)
197
−4.45 (4.37)
−5.00 (−16.00 to 10.00)*
T2–T12 kyphosis (°)
208
38.82 (17.75)*
37.50 (2.00 to 93.00)
T2–T5 kyphosis (°)
202
9.88 (8.63)
T5–T12 kyphosis (°)
205
32.09 (18.41)*
T10–L2 kyphosis (°)
211
10.40 (15.28)
C0–C2 lordosis (°)
213
32.31 (10.17)*
C2–7 lordosis (°)
213
5.72 (14.07)*
T1 slope (°)
213
23.88 (11.26)*
9.00 (−19.00 to 41.00)* 30.00 (−16.00 to 88.00) 8.00 (−33.00 to 77.00)* 33.00 (−7.00 to 68.00) 6.00 (−33.00 to 49.00) 24.00 (−1.00 to 63.00)
Thoracic inlet angle (°)
213
70.45 (14.66)*
69.00 (12.00 to 115.00)
Odontoid SVA (mm)
213
20.76 (16.53)*
20.59 (−24.58 to 78.75)
Major curve cobb angle (°)
210
48.59 (19.54)*
47.5 (−89 to 114)
ODI score
189
24.98 (18.03)
20.00 (0.00 to 100)*
SF-36 MCS score
187
44.20 (9.74)*
44.47 (18.54 to 67.98)
SF-36 PCS score SRS-22 subtotal score
187 192
42.45 (8.31) 3.34 (0.67)*
44.37 (20.77 to 60.40)* 3.40 (1.21 to 4.75)
SD standard deviation, ° degree, mm millimeter * The value which the evaluation of descriptive statistics performed (preferred because of the distribution of the variable)
123
Eur Spine J
145
72.5
PT, sacral slope (SS), SVA, T1 sagittal tilt, T2–T12 kyphosis, T2–T5 kyphosis, T5–T12 kyphosis, and T10–L2 kyphosis) as well as HRQOL parameters [Oswestry Disability Index (ODI), SF-36 Mental Component Score (MCS), SF-36 Physical CS, SRS 22 subtotal] using Pearson correlation analysis. In addition, the CS alignment in these patients was further classified into four types [cervical non-kyphosis (CNK), cervical kyphosis (CK), cervical-middle-thoracic kyphosis (CMTK) and cervical-lower-thoracic kyphosis (CTLK)] as described by Yu and coworkers [5] in a population of adolescent idiopathic scoliosis, then compared for all the other parameters that were listed above.
29 26
14.5 13
Statistical analysis
Table 2 Descriptive statistics for categorical variables Variables
n
%
Gender Female Male
177
83.1
36
16.9
SRS-Schwab classification-coronal D
109
51.7
L
42
19.9
N
34
16.1
T
26
12.3
SRS-Schwab classification-sagittal, PI-LL 0 + ++
SRS-Schwab classification-sagittal, PT 0
129
64.2
+
50
24.9
++
22
10.9
SRS-Schwab classification-sagittal, SVA 0
166
80.2
+
35
16.9
6
2.9
++
alignment and HRQOL parameters, in patients with untreated adult idiopathic scoliosis.
Patients and methods A retrospective review of prospectively collected data from a multicentre database on adult spinal deformity was performed. The criteria to be included in this database were defined as a patient having any or any combination of thoracic kyphosis exceeding 60°, coronal deformity exceeding 20°, pelvic tilt exceeding 25° and sagittal vertical axis exceeding 50 mm. Of 468 consecutive adult IS patients with specific diagnosis of IS defined by the treating physician(s) at the time of entry, 213 were included in the study; the remainder were excluded due to poor quality X-rays on which the CS was not properly visible, or previous spinal surgery in order not to create a bias. Standing AP and lateral full spine X-rays were measured for the following CS parameters: Cranial baseC2 (C0–C2) lordosis, C2–C7 lordosis, T1-slope, thoracic inlet angle (TIA) and odontoid (Od)-T1 offset in accordance with the landmarks described by Ames and coworkers [10] using a measurement software (Surgimap measurement tool provided by SRS). These measurements were then evaluated for possible associations with patient age, pre-existing alignment parameters (Global Tilt [11], Lordosis Gap [12], lordosis L1–S1, lordosis T12–S1, PI,
In accordance with the shape of the data set of variables, mean and median values were given as descriptive statistics. Two group comparisons were handled by t test or Mann–Whitney U test statistics according to normality assumption implemented. Likewise, more than two group comparisons were processed by ANOVA or Kruskal– Wallis test statistics based on normality assumption. The relationships between categorical variables were evaluated by Chi-square test. Correlations between two continuous variables were analysed by Pearson correlation coefficient or Spearman’s correlation coefficient rendering assumption of normality. Type-I error rate was taken as α = 0.05 for statistical significance. SPSS 21.0 was used for statistical analyses [13].
Results The descriptive statistics of the continuous and categorical variables can be seen in Tables 1 and 2. Means and standard deviations for CS alignment parameters were 32.3° ± 10.2° for C0–C2; 5.7° ± 14.1° for C2–C7; 23.9° ± 11.3° for T1-slope, 70.5° ± 14.7° for TIA and 20.8° ± 16.5° for Od-T1 offset. Table 3 demonstrates the statistical evaluation and the relationships between the CS and clinical coefficients. The CS alignment parameters did not demonstrate a uniform pattern of correlation with age as well as the sagittal alignment parameters. Cranio-cervical lordosis angle was not found to be correlated with any parameter. Od-T1 offset was found to be correlated only with T1 sagittal tilt and parameters of LL and TK. Subaxial kyphosis, T1-slope and T1 inclination were found to be strongly correlated with age (in addition to the parameters that correlated with the Od-T1 offset). Based on this finding, all other correlation analyses were performed after normalisation of the data by age. Of interest, in general, the CS alignment parameters correlated neither with the
123
Eur Spine J Table 3 Correlation matrix between C0–C2, C2–7, T1Slope, TIA, Odontoid SVA variables and clinical coefficients
Variables
C0–C2
C2–7
T1-Slope
TIA
Odontoid SVA
Age Pearson correlation p value
−0.041
0.208*
0.209*
0.550
0.002
0.002
0.273**
0.334**
0.273**
