For the O-arm procedure we used the O-arm (Medtronic PLC, Littleton, Massachusetts, USA) integrated with Stealth Station Navigation System (Medtronic PLC, Louisville, Colorado, USA). Patients under general anaesthesia were placed prone on the radiolucent table. Sterile preparation of the operation site was followed by attachment of the reference frame to the spinous process and three-dimensional (3D) examination of the treated spinal segment with the O-arm. During the data acquisition (not exceeding 30 s), all medical personnel were outside the operating theatre. The data were automatically transmitted to the neuronavigation system (Figure 1 ) and used to guide the vertebroplasty needle into the target vertebra (Figures 2 , 3 ). After proper needle placement the PMMA was injected under the real-time image given by the O-arm switched to the fluoroscopy mode.
The O-arm also enabled post-procedural 3D imaging to be obtained to estimate the result of vertebral body filling and to visualize potential extravertebral cement leak. Mean volume of PMMA injected per vertebra was 4.03 ml (range: 2.0–7.5 ml). Radiation dose and time were recorded by a built-in dosimeter. In the lumbar vertebrae mean volume of injected PMMA was higher than in the thoracic ones (respectively: 4.58 ml and 3.42 ml).
The O-arm also enabled post-procedural 3D imaging to be obtained to estimate the result of vertebral body filling and to visualize potential extravertebral cement leak. Mean volume of PMMA injected per vertebra was 4.03 ml (range: 2.0–7.5 ml). Radiation dose and time were recorded by a built-in dosimeter. In the lumbar vertebrae mean volume of injected PMMA was higher than in the thoracic ones (respectively: 4.58 ml and 3.42 ml).