Background: Proximal junctional kyphosis (PJK) is a common complication following adult spinal deformity (ASD) surgery and puts patients at an increased risk for neurological injury. As reoperation continues to be the mainstay treatment, there is utility in identifying independent preoperative risk factors for PJK development. The aim of this study was to determine whether a history of anterior cervical discectomy and fusion (ACDF) predicts increased incidence of PJK after ASD correction.

Methods: Data was retrospectively collected from the medical record of patients who underwent ASD long-segment spinal fusion between 10/2015 and 9/2020. Patients were divided into cohorts based on whether they had previously undergone ACDF. Demographic, radiographic, perioperative, complication, and patient-reported outcomes measures (PROMs) were analyzed. The primary outcome measure was the development of PJK by the 2-year postoperative timepoint.

Results: Eighty-six patients met inclusion criteria, 14 of which had previously undergone ACDF. Patients with prior ACDF demonstrated a significantly higher risk of developing PJK by 2 years after ASD surgery. The prior ACDF cohort also showed significantly greater proximal junctional sagittal cobb angles (PJCA) from the upper instrumented vertebra (UIV) to UIV+2 at 2-years postoperatively, greater pre- to postoperative changes in PJCA at 1-year postoperatively, and less absolute global sagittal flexibility than the no prior ACDF cohort. No differences were seen in demographic, comorbidity, complication, or PROM data between groups.

Conclusions: These retrospective data demonstrate that a history of ACDF may independently predict the development of PJK after ASD correction and should be considered in the operative decision-making for these patients.