State of the art: proximal junctional kyphosis-diagnosis, management and prevention.

Proximal junctional kyphosis (PJK) is a common problem that may occur following the surgical treatment of adult patients with spinal deformity. It is defined as the proximal junctional sagittal angle from the UIV and UVI + 2 of at least 10° AND at least 10° greater than the preop measurement. The reported incidence of radiographic PJK in the literature varies between 17 and 46%. A smaller subset of these patients may need revision surgery and are defined as proximal junctional failure (PJF), which can be associated with vertebral fracture, vertebral subluxation, failure of instrumentation, and neurological deficits. Several risk factors for development of PJK have been proposed. However, large-scale prospective studies are needed to better identify strategies to reduce the incidence of PJK.