84. Low density pedicle screw constructs are associated with lower incidence of proximal junctional failure in adult spinal deformity surgery

Abstract

BACKGROUND CONTEXT Proximal junctional failure (PJF) is a common and particularly adverse complication of adult spinal deformity (ASD) surgery. There is evidence that the rigidity of posterior spinal constructs may impact risk of PJF. PURPOSE We hypothesized that lower mean screws per level and decreased rod stiffness would be associated with lower incidence of PJF. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE Patients with ASD and 2-year minimum follow-up were included. Only patients undergoing fusion of ≥5 levels, and with LIV at the sacro-pelvis were included. Patients undergoing revision surgery were excluded. In total, 420 patients were analyzed. OUTCOME MEASURES The primary outcome variable was PJF, defined using previously published radiographic criteria (PJ angle >28°and ∆PJ angle >22°, and ≥8mm/≥3mm listhesis at upper thoracic / thoracolumbar levels, respectively). METHODS The primary independent variables were the mean number of screws per level fused analyzed with a cutoff of 1.8 (determined by ROC analysis) and rod material/diameter. Multivariable logistic regression was utilized to investigate confounding factors, including age, history of osteoporosis, BMI, gender, CCI, preoperative Schwab modifiers, preoperative TPA, postoperative change in lumbar lordosis, upper instrumented vertebra, osteotomy, approach, UIV type (ie, pedicle screw vs other), and number of levels fused. RESULTS Of the total patients, 78.8% were female. PJF occurred in 14.1% of patients. The mean screws per level was 1.7 (SD 0.2), and 57.6% of patients had 0.2) were not significantly associated with PJF. Screw density specifically adjacent to the UIV was not related to PJF (p>0.2). CONCLUSIONS Among ASD patients undergoing long-segment primary fusion to the pelvis, the risk of PJF was lower among patients with FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.