Proximal Junctional Kyphosis in Adult Degenerative Scoliosis - Does the Solution Still Elude Us?

Proximal functional kyphosis (PJK) is a common complication (26-39%) following multilevel instrumented fusion for spinal deformities. It is defined as a focal segmental kyphosis of more than 10 degrees between upper instrumented vertebra (UIV) and 2 levels cranial to UIV (UIV+2); and a focal increase in kyphosis of more than 10 degrees between UIV and UIV+2 [1]. Although the clinical impact of this radiological phenomenon was initially unclear, recent literature has clearly demonstrated it to be the most common cause for revision surgical interventions following spinal deformity correction surgeries [2]. The exact cause underlying this complication has still remained elusive. Nevertheless, multiple clinical and radiological factors have been shown to negatively influence the alignment of spinal segments immediately proximal to the fused vertebrae [3].