The Evaluation, Prevention, and Management of Proximal Junctional Kyphosis and Failure.

Proximal junctional kyphosis (PJK) occurs commonly after surgery for adult spinal deformity. PJK exists on a spectrum, from a pure radiographic diagnosis to those patients with more severe deformity leading to notable pain, morbidity, and neurologic compromise requiring revision surgery-often described as proximal junctional failure (PJF). In this review, we describe the evaluation of patients with PJK and PJF, including different classification systems as well as modifiable and nonmodifiable risk factors. We then discuss the wide variety of strategies that have been proposed to reduce the risk of PJK and PJF. These include optimizing bone health with anabolic agents, use of bone cement at levels above the upper instrumented vertebra, optimizing alignment targets for correction, upper instrumented vertebra selection, posterior ligamentous complex preservation and augmentation, inducing a more gradual transition in stiffness above the construct, and instrumentation modifications. We end with a discussion of nonsurgical and surgical management of PJK, as well as our approach to revision surgery after PJF. Although a substantial increase in research on this topic has enhanced our understanding of proximal junction pathologies, notable work remains to demonstrate the reliability and reproducibility of prevention strategies.