Lumbar Scoliosis (Degenerative) MIS Surgery (PJK) Complication

Abstract

Proximal junctional kyphosis (PJK) is a common complication of thoracolumbar deformity surgery. It is usually defined as an increase of greater than 10° of kyphosis at the proximal segment of fusion, measured using the Cobb angle from the inferior end plate of the uppermost instrumented vertebra (UIV) to the superior end plate of the supra-adjacent segment 2 levels proximally (UIV + 2). PJK can be asymptomatic, with a limited impact on clinical outcome. However, it can be symptomatic resulting in worsened pain or neurologic deficit which is referred to as proximal junctional failure. There is no known single cause for PJK, though numerous risk factors have been proposed including advanced age, osteopenia/osteoporosis, inclusion of the sacrum in the fusion, severe deformity, and failure to achieve global sagittal balance among others. Injury of the posterior elements and muscular support due to exposure-related morbidity could also play a role in the development of PJK. Treatment options vary depending on the clinical scenario, with asymptomatic cases calling for observation and serial imaging, while others necessitate revision surgery. Revision surgery typically includes adequate decompression, if necessary, and extension of fusion with the goal of maintenance of appropriate sagittal alignment.