Prediction value of hounsfield units at upper instrumented vertebra for postoperative proximal junctional kyphosis after pelvic fixation with second sacralalar-iliac in patients with degenerative spinal deformity
10.3760/cma.j.cn121113-20230912-00166
- VernacularTitle:经骶2骶髂螺钉固定的退行性脊柱畸形患者上端固定椎HU值对术后近端交界性后凸的预测价值
- Author:
Xing SUN
1
;
Jie LI
;
Yanjie XU
;
Zongshan HU
;
Ziyang TANG
;
Hui XU
;
Zhen LIU
;
Yong QIU
;
Zezhang ZHU
Author Information
1. 南京医科大学鼓楼临床医学院骨科脊柱外科，南京 210008
- Keywords:
Osteoporosis;
Bone density;
Pelvis;
Adult spinal deformity;
Proximal junctional kyphosis;
Hounsfield unit
- From:
Chinese Journal of Orthopaedics
2024;44(11):730-739
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the effect of Hounsfield Units (HU) at the upper instrumented vertebra (UIV) on postoperative proximal junctional kyphosis (PJK) after pelvic fixation with second sacral alar-iliac (S 2AI) screws in patients with degenerative spinal deformity. Methods:A total of 66 patients with degenerative spinal deformity who underwent pelvic fixation with S 2AI screws from August 2015 to April 2021 were retrospectively reviewed. The cohort included 4 males and 62 females, aged 61.9±7.3 years (range, 43-78 years), with a follow-up period of 18.4±14.3 months (range, 6-60 months). The prevalence of PJK was 26%. Patients were divided into two groups based on the occurrence of PJK during postoperative follow-up: the PJK group (17 cases) and the non-PJK group (49 cases). HU measurements were taken at the UIV, the vertebral body cephalad to the UIV (UIV+1), and the L 3 and L 4 vertebral bodies. The following sagittal radiographic parameters were measured: thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), PI minus LL (PI-LL), and sagittal vertical axis (SVA) at preoperative, postoperative, and final follow-up. General information and HU values of the two groups were compared, and Pearson correlation analysis was performed on HU values, bone mineral density (BMD), and T scores. Logistic regression analysis was used to explore the risk factors for PJK. Results:The HU values of L 3 and L 4 were significantly positively correlated with the BMD and T scores respectively ( r=0.530, P<0.001; r=0.537, P<0.001). Age, gender, follow-up time, fixation levels, bone mineral density (BMD) and T-score were not significantly different between PJK and non-PJK group. The average HU values of UIV and UIV+1 in PJK group was 104.3±32.9, whlie the average HU values of UIV and UIV+1 in non-PJK group was 133.7±29.5. The difference of HU between the two groups was statistically significant ( t=3.441, P=0.001). Logistic regression analysis showed that average HU values of UIV and UIV+1 [ OR=0.960, 95% CI(0.933, 0.987), P=0.004] and changes of lumbar lordosis [ OR=1.049, 95% CI(1.007, 1.092), P=0.023] were independent risk factors for PJK, with an optimal cutoff obtained by ROC that 106 for average HU values of UIV and UIV+1 and 22.5° for changes of LL. Conclusion:The average HU values of UIV and UIV+1 < 106 and changes of lumbar lordosis > 22.5° are independent risk factors for PJK after pelvic fixation with second sacralalar-iliac in patients with degenerative spinal deformity.
