Preoperative Predictors of Proximal Junctional Failure Occurrence in Adult Spinal Deformity Surgery with T4-Pelvic Fusion

Abstract

Introduction: Proximal Junctional Kyphosis/Failure (PJK/F) is a complication that can be prevented by adult spinal deformity surgery. Some adult spinal deformities require fusion from the upper thoracic spine to the pelvis. However, there is no consensus regarding the upper instrumented vertebrae (UIV). We investigated preoperative predictors of PJF in patients with T4 UIV.

Methods: 60 patients with spinal deformity who underwent T4 to pelvic fusion between September 2012 and September 2021 were divided into a PJF group (5 cases) and a control group (55 cases) and analysed for preoperative Body Mass Index (BMI), Hounsfield Unit (HU) value of T4 vertebra, PI, PT, LL, PI-LL, T1 slope, TK, uTK (angle between T1 cephalic endplate and T5 caudal endplate on lateral X-ray of the standing full spine), f-TK (TK in antevertebral position), f-uTK (uTK on the lateral X-ray of the antevertebral full spine), Global tilt, postoperative PT, LL, T1 slope, TK, PI-LL, uTK, Global tilt, Global alignment and proportion (GAP) scores were examined.

Results: PI was 61.8±4.3° in the PJF group versus 50.4±1.7° in the control group (p = 0.0322). f-uTK was 34.6±3.6° in the PJF group versus 14.4±1.3° in the control group (p = 0.00042). Multiple logistic analysis revealed an odds ratio of 1.12 (95% confidence interval 0.95-1.33, p = 0.173) for PI and 1.69 (95% confidence interval 0.98-2.9, p = 0.0588) for f-uTK for the incidence of PJF. ROC analysis of f-uTK values for the occurrence of PJF showed that 28° was a valid cutoff value (sensitivity, 1; specificity, 0.944).

The only postoperative factor that differed significantly was T1 slope, which was 47.6±5.9° in the PJF group versus 33.5±1.6° in the control group (p = 0.0284).

Conclusions: In patients with f-uTK > 28°, more cranial UIV than T4 should be considered to prevent PJF.