Anales de la RANM

188 A N A L E S R A N M R E V I S T A F U N D A D A E N 1 8 7 9 THORACOLUMBAR ROTATIONAL KYPHOSIS Pizones J, et al. An RANM. 2022;139(02): 186 - 195 Postoperative SS dictated the type of postoperative Roussouly sagittal shape (R-type 1 and 2, SS < 35°; R-type 3, SS = 35°-45°; R-type 4, SS > 45°) [6]. Preoperative PI dictated the ideal sagittal shape (R-type 1 and 2, PI < 45°; R-type 3, PI = 45°-60°; R-type 4, PI > 60°) [7]. Sagittal type matching was calculated from the difference between ideal type and postoperative type. We investigated the assocaition between these variables and postoperative ideal type mismatch and mechanical complications (proximal junctional kyphosis or failure, rod breakage and screw failure), placing special focus on the consequences of TL sagittal change. We also compared results in patients with high-PI (PI > 50°) and patients with low-PI (PI < 50°). The statistical analysis was performed with SPSS version 20 (SAS Institute Inc., Cary, NC, USA). The distribution of variables were expressed as mean and standard deviation. Normal distribution of the variables was evaluated using Kolmogorov- Smirnov test. Univariate analysis was performed comparing qualitative variables using chi-square statistics (and Fisher test when necessary), and quantitative variables using the Student-t test or analysis of variance (ANOVA) with Bonferroni correction. Multivariate logistic regression analysis was performed to identify independent factors associated with mechanical complications and sagittal shape matching. The significance threshold was set at 5% ( P < 0.05). Sample description At the time of data extraction (July 2020), the database contained 1217 operated patients, 574 of whom had a scoliosis with a main coronal TL/L curve > 30°. Of these patients, 185 (32%) fulfilled the T10-L2 kyphosis > 20° criterion and 171 had at least 2 years of follow-up. Our study cohort therefore comprised 171 patients. The mean age was 57.8 ± 14.8 years, mean preope- rative TL Cobb angle was 53.8 ± 16.9°, and preope- rative TLK was 34.4 ± 13° (Table 1). The LIV was the pelvis in 48.6% of the patients and 51.4% were instrumented at L5 or above (15.5% at L5, 28.4% at L4, 7.4% at L3). The UIV was between T2-T6 in 49.7% of the patients, and between T7-T10 in 50.3% of them. Surgery achieved a TLK mean correction of 21.4 ± 18.1°. This shifted the inflection point to a higher position by a mean of 1.4 ± 1.25 segments. Mechanical complications Postoperative mechanical complications were found in 38% of the patients (Table 2). The univariate analysis showed that older patients as well as those instrumented to the pelvis (iliac) were statistically more prone to have mechanical RESULTS Table 1.- Sample description Preoperative Postoperative P TL Cobb (°) 53.8 ± 16.9 28.9° ± 17.3 0.000* TLK (°) 34.4 ± 13 13.2° ± 13.5 0.000* TL translation (mm) 40.7 ±  18.6 24.7 ± 15.7 0.000* Max LL (°) 51.7 ± 13.5 52 ± 13.1 0.436 PI (°) 51.9 ± 12.2 51.7 ± 11.8 0.415 PT (°) 24.2 ± 11.7 20.8 ± 9.4 0.000* SS (°) 27.4 ± 11.1 29.5 ± 13.2 0.826 TL Cobb: thoracolumbar coronal Cobb angle; TLK: thoracolumbar kyphosis; Max LL: maximal lumbar lordosis; PI: pelvic incidence; PT: pelvic tilt; SS: sacral slope. * statistical significance