Protective Factors of Preventing Proximal Junctional Kyphosis as the Most Common Complication of Adult Spinal Deformity Surgery

Background and Aim: This study aims to provide information about the common complications of adult spinal deformity (ASD) surgery that requires revision surgery and proximal junctional kyphosis (PJK) as the most common complication. We emphasized crucial protective factors that reduce the risk of post-operative PJK, especially the careful selection of the upper instrumented vertebra (UIV) and gradual transitional zone on the proximal end of the construct. Methods and Materials/Patients: This study is a retrospective review of the adult population with spinal deformity who underwent posterior instrumentation surgery and requires revision surgery due to post-operative complications, such as disc herniation, screw loosening, rod breakage, distal junctional failure, and symptomatic PJK. Fifteen ASD patients requiring revision surgery were included. We evaluated the ratio of age, gender, the prevalence of postoperative complications, and the most common complication of PJK based on Cobb angle and patient symptoms. Results: This study included 15 patients with ASD who underwent posterior spinal instrumentation surgery and experienced post-operative complications requiring revision surgery. As a result, 6 patients out of 15 (40%) had PJK, four patients (26.6%) had disc herniation and canal stenosis, two patients (13.3%) had screw loosening, one patient (6.6%) had rod breakage and two patients (13.3%) had distal junctional failure required revision surgery. Conclusion: In our study, PJK is at the top of the complications and two risk factors have a great impact on predisposing ASD surgery to the post-operative PJK, that is, the UIV level, and gradual transitional zone at the proximal end of the construct, therefore the risk of this unfortunate outcome can be significantly minimized by carefully selecting UIV and hooks using a smooth gradual transitional zone along with other protective factors.