Descriptive statistics of various factors and their correlation with operative duration by bivariate analysis.
| Factors | Summary Statisticsa | Operative Duration, minb, mean ± SD | Association with Operative Duration |
| Patient-specific factors | |||
| Age, y | 15.8 ± 3.8 | - | 0.08 (0.39)c |
| Sex | 0.83 (0.10)d | ||
| M | 42 (32%) | 243 ± 68 | |
| F | 88 (68%) | 231 ± 66 | |
| BMI | 21.1 ± 2.3 | - | 0.08 (0.39)c |
| Cobb angle (of the major structural curve) | 64.7° ± 13.6° | - | 0.38 (0.0001)c |
| Flexibility index (of the major structural curve) (%) | 23.9 ± 12.8 | - | −0.21 (0.02)c |
| C-DAR | 8.7 ± 2.1 | - | 0.13 (0.15)c |
| T-DAR | 10.3 ± 4.4 | - | 0.09 (0.32)c |
| Thoracic kyphosis | 32.3° ± 14.6° | - | 0.12 (0.19)c |
| Lumbar lordosis | 49.2° ± 14.8° | - | 0.10 (0.26)c |
| Axial rotation (Nash and Moe grade) | 3.62 (0.01)d | ||
| 1 | 14 (9.3%) | 228 ± 68 | |
| 2 | 68 (45.3%) | 219 ± 62 | |
| 3 | 43 (28.7%) | 261 ± 83 | |
| 4 | 25 (16.7%) | 263 ± 64 | |
| Lenke curve type | 0.78 (0.50)d | ||
| 1 | 90 (60%) | 232 ± 68 | |
| 2 | 2 (1.3%) | 212 ± 57 | |
| 3 | 23 (15.3%) | 258 ± 65 | |
| 4 | 0 | - | |
| 5 | 23 (15.3%) | 216 ± 68 | |
| 6 | 12 (8%) | 248 ± 56 | |
| Procedure-specific factors | |||
| Number of levels fused | 11.8 ± 2.1 | - | 0.29 (0.003)c |
| Number of screws inserted | 17.6 ± 3.4 | - | 0.33 (0.008)c |
| Type of osteotomy used | 0.14 (0.18)d | ||
| 1 | 118 (78.7%) | 235 ± 72 | |
| 2 | 25 (16.7%) | 229 ± 52 | |
| 3 | 5 (3.3%) | 254 ± 81 | |
| 4 | 2 (1.3%) | 264 ± 32 | |
| Surgeon-specific factors | |||
| Experience of the chief surgeon (y) | 6.1 (4.9, 7) | - | −0.36 (0.001)e |
| Experience of the first assistant (mo) | 39 (26, 58) | - | −0.21 (0.08)e |
| Number of assistants | 3 (2, 3) | - | −0.12 (0.11)e |
↵a Mean ± SD for continuous variables with normal distribution, median (first quartile, third quartile) for continuous variables with non-normal distribution, frequency/percentage for categorical variables.
↵b Mentioned separately for each group for categorical variables only.
↵c Pearson‘s correlation was used for continuous variables with a normal distribution. Figure in cells denotes the Pearson’s correlation coefficient “r” with P value in brackets.
↵d 1-way analysis of variance used for categorical variables. Figure in cells denotes the ”F” value with P value in brackets.
↵e Spearman’s rank correlation was used for continuous variables with non-normal distribution. Figure in cells denotes the Spearman’s rank correlation coefficient ‘ρ (rho)’ with P value in brackets.
BMI, body mass index; C-DAR, coronal deformity angular ratio; T-DAR, total deformity angular ratio.