The combined anteroposterior fusion with vertebral body replacement (VBR) using a wide footplate expandable cage with a minimally invasive lateral approach has been widely used for pseudoarthrosis after osteoporotic vertebral fractures. The purpose of this study is to evaluate the radiological results of combined anteroposterior surgery using VBR and to recommend the optimal procedure. Thirty-eight elderly patients were included in this study. The mean preoperative local kyphosis angle was 29.3°, and the mean correction loss angle was 6.3°. Cage subsidence was observed in ten patients (26.3%), and UIV or LIV fracture in twelve patients (31.6%). Patients with cage subsidence were compared to those without cage subsidence to determine the causal factors. The mean number of fixed vertebrae was 5.4 vertebrae with cage subsidence and 7.4 vertebrae without cage subsidence. In addition, to precisely clarify the optimal number of fixed vertebrae, those patients with two above-two below fixation were compared to those with less than two above-two below fixation, which revealed that the correction loss angle was significantly less in two above-two below fixation (p = 0.016). Based on these results, we recommend at least two above-two below fixation with VBR to minimize the correction loss angle and prevent cage subsidence.
Keywords: combined anteroposterior fusion; minimally invasive spinal treatment (MIST); osteoporotic vertebral body fracture (OVF); percutaneous pedicle screws (PPS); vertebral body replacement (VBR); wide footplate expandable cage.