Proximal junctional kyphosis and failure: How much can we attribute to known risk factors?

Abstract

BACKGROUND CONTEXT: Despite advancements in the understanding of spinal alignment and in instrumentation for adult spine deformity (ASD) surgery, complications such as proximal junctional kyphosis and proximal junctional failure (PJK/PJF) continue to be a significant concern. PURPOSE: To assess the attributable risk of various reported contributors to development of PJK/PJF. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: A total of 464 ASD patients. OUTCOME MEASURES: Odds ratios of PJK/F risk factors. METHODS: We included ASD patients with complete baseline (BL) and up to 2Y clinical, radiographic and HRQL data. Stratified according to development of PJK/PJF by 2 years. Means comparison analyses compared outcomes between groups. Backstep logistic regression assessed factors predictive of PJK/F development. RESULTS: There were 464 patients included (age: 59.8 ± 14.3 years, BMI: 26.9 ± 5.5 kg/m2, CCI: 1.65 ± 1.68). 80.5% of patients were female; 173 patients (37.3%) formed the PJK/F+ group, as at 2 years (173 PJK and 28 PJF patients). At BL, PJK/F+ patients were older (63.2 vs 57.9 years, p<0.001) and had worse deformity (PI-LL 20.3 vs 11.8, p<0.001). There were no differences between groups in baseline disability, demographic, frailty or comorbidity factors. Controlling for age and baseline deformity, PJK/F+ patients were more likely to develop mechanical complications (OR 2.1, 95% CI: 1.2-3.7, p=0.007). Use of PJK prophylaxis techniques did not have a significant effect on risk of developing PJK/F (p=0.307). Factors associated with increased risk of developing PJK/F were significant baseline deformity (OR 1.02, 95% CI: 1.01-1.03, p=0.026), peripheral vascular disease (OR 5.5, 1.3-23.6, p=0.023), undergoing an osteotomy (OR 1.7, 1.1-2.8, p=0.017) and age >60 (OR 1.1, 1.1-1.2, p=0.026) and hypertension (OR 2.01, 1.04-3.87, p=0.038). Diabetes was associated with lower odds for developing PJK/F+ (OR: 0.3, 95% CI: 0.1-0.8, p=0.018). CONCLUSIONS: Proximal junctional kyphosis/failure remains a significant postoperative concern in the ASD population. With currently known risk factors, we are still unable to fully quantify and predict a patient's total risk for developing postoperative PJK/F. Further work is needed to delineate contributing factors that are yet to be determined. FDA Device/Drug Status: This abstract does not discuss or include any applicable devices or drugs.