(AS2) Calibration of Comprehensive Predictive Model for the Development of Proximal Junctional Kyphosis and Failure in Adult Spinal Deformity Patients with Consideration of Contemporary Goals and Techniques
Spine Surgeon NYU School of Medicine New Canaan, Connecticut, United States
Disclosure(s):
Peter G. Passias, MD: Cerapedics: Consultant (Ongoing); Globus Medical: Consultant (Ongoing); Journal of Neurosurgery: Spine: Board Member/Officer/Trustee (Ongoing); Medtronic: Consultant (Ongoing); Nuvasive: Consultant (Ongoing); Royal Biologics: Consultant (Ongoing); Spine: Board Member/Officer/Trustee (Ongoing); Terumo: Consultant (Ongoing)
Introduction: Proximal junctional kyphosis (PJK) and failure (PJF) development remains a major concern after adult spinal deformity (ASD) corrective surgery. There remains a paucity of literature utilizing contemporary alignment metrics and novel prophylaxis measures to predict occurrence of PJK and PJF.
Methods: Operative ASD patients with baseline (BL) and 2-year (2Y) postoperative data were included. PJK was defined as ≥10° in sagittal Cobb angle between inferior UIV endplate and superior endplate of UIV+2. PJF was defined as meeting Lafage et al. criteria by 2Y. Backstep binary regression analysis assessed BL demographic, clinical and surgical information to predict the occurrence of PJK and PJF. Internal cross validation of the model was performed via 70:30 cohort split. Conditional inference tree (CIT) analysis determined thresholds at (α=.05).
Results: 779 ASD patients (59.87±14.24 years, 78% female, 27.78±6.02kg/m2, mean CCI: 1.74±1.71) were included. 60.5% of patients (n=471) developed PJK, and 10.5% (n=82) developed PJF by their last recorded visit. The six most significant demographic, radiographic, surgical, and post-operative predictors of PJK/PJF were: BL age ≥ 74, BL SAAS T1PA modifier >1, BL SAAS PT modifier >0, levels fused > 16, nonuse of prophylactic hooks, and 6W SAAS PI-LL modifier > 1 (all p < .015) (Table 1). Overall, the model was deemed significant (p < .001), and internally validated ROC analysis returned an AUC of .923, indicating robust model fit.
Conclusion : Proximal junctional kyphosis and failure remain critical concerns in adult spinal deformity surgery, and efforts to reduce the occurrence of PJK and PJF have resulted in the development of novel prophylactic techniques and enhanced clinical and radiographic selection criteria. This study demonstrates a validated model incorporating such techniques that may allow for the prediction of clinically significant PJK and PJF, and thus assist in optimizing patient selection, enhance intraoperative decision making, and reduce post-operative complications in ASD surgery.
