Fig. 3

A–I A 75-year-old female patient with Kümmell’s disease at L1 in PKP group: A Lateral radiograph before surgery; B Intravertebral vacuum sign shown in sagittal computed tomography (CT) images before surgery; C A low signal intensity in the location of the cleft shown in sagittal T1-weighted MRI image before surgery; D–E Intervertebral cement leakage is shown in lateral radiograph and sagittal CT images after surgery; F An adjacent fracture was noted in MRI image one month after PKP surgery. G Lateral radiograph after secondary PKP surgery; H MRI image showed the fracture remained nonunion about three months after secondary PKP surgery; I Lateral radiograph after internal fixation with cement augmentation