Analysis of the causes of proximal junctional kyphosis following spinal instrumented fixation in patients with bone mineral density deficiency

Objective To explore causes of proximal junctional kyphosis (PJK) following instrumented fixation of lumbar spine in patients with degenerative scoliosis due to mineral bone density deficiency. Material and methods A retrospective analysis was conducted on 308 patients with degenerative lumbar scoliosis surgically treated with decompression of neural elements, deformity correction and stabilization of FSU using rigid transpedicular fixation systems. The patients were followed up for 2 years of surgery and were subdivided into 2 groups, those who developed PJK (n=132) and those who did not (n=176). Variable risk factors for PJK described in the literature were analyzed. They could be categorized into patient related factors (age, gender, osteoporosis, body mass index (BMI), smoking habits), surgical factors (type of osteotomy performed, a magnitude of lordosis correction, long fixation to the sacrum) and radiographic parameters (PI, TK, LL, SVA, PI-LL, PJA). Results Osteoporosis (53-33 %, p = 0...