O arm

In OLIF, the patient was placed in the right decubitus position. A transverse incision of approximately 4 cm was made on the skin in the left lateral region of the abdomen. After dissection of the external oblique, internal oblique, and transverse abdominal muscles, the retroperitoneal space was accessed by blunt dissection through the retroperitoneal fat tissue. The psoas muscle was retracted posteriorly. The targeted intervertebral disc space was exposed, and the tubular retractor system was set. Under direct visualization, a discectomy was performed and both cartilaginous endplates were thoroughly removed, and the polyetheretherketone (PEEK) cage with allograft was placed in the disc spaces. After performing OLIF, percutaneous screw insertion to the cephalad and caudal vertebrae was performed in the lateral position without position change using an intraoperative three-dimensional computed tomography (3D-CT)-based navigation system (O-arm; Medtronic, Minneapolis, MN, USA). We used the modified cortical bone trajectory (CBT) screw technique as previously reported (Fig. 2) [18 (link)]. Rods were then placed. This series of procedures were performed without intraoperative neuromonitoring. After the surgery, the patient was allowed to walk with a hard brace and was required to wear the brace for at least 2 months after the surgery (Fig. 3).

In the prone position, the head was placed in a 3-point skull fixation system (Mayfield headrest) and the neck slightly flexed; a preoperative 3D radiographic reconstruction with OArm (Medtronic) was acquired.
Under EX vision and magnification, by means of a midline linear incision, C0–C3 skeletonization was performed to expose posterior CVJ. With the aid of neuronavigation, a posterior instrumentation was variably performed. We used screws into the occipital crest in cases 1, 2, 3, 5, 6, and case 4 (redo surgery). On the other hands, C2 isthmic screws were put in cases 4 and 6, laminar screws in cases 1, 2, 3, 5, and case 4 (redo surgery), in C3 lateral masses in cases 1, 2, 3, 5, 6, and case 4 (redo surgery). In one case, screws were put also in C4 (case 5) (OCT 2-VUE POIN® Nuvasive System). All the constructs were fixed with bilateral hinged rods [Table 2]. Bone Fusion was performed by decorticating the occiput and posterior arches of the cervical facet joints by high-speed drill and curettes, along with demineralized bone paste (AttraX^® PUTTY Nuvasive) to stimulate bone fusion. Finally, further OArm acquisition documented the satisfactory placement of the stabilization system.
The clinical follow-up evaluation was performed according to the Nurick's Grade at different time points. According to one-way repeated-measures ANOVA, changes are considered significant when P < 0.05.

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).

Ten fresh, adult human cadavers were utilized; none had been previously used for any other purpose. With the cadavers in a prone position, the atlas and axis posterior surfaces were exposed. All cadavers underwent a 3D baseline radiologic assessment using an O-arm (Medtronic PLC, Littleton, MA, USA) to assess anatomic variations.
Dissection of the medial edge of the atlas was performed under magnification. The ALM entry point was 2 mm lateral to MEC1. C1 cortex penetration was performed using a high-speed drill, and a tap was used to advance into the ALM. The planned trajectory was perpendicular to the horizontal plane and parallel to the inferior border of the C1 posterior arch (IAC1), as previously suggested.[1 (link)] Multiaxial screws (Vertex, Medtronic Sofamor Danek, Memphis, TN, USA) were used. All instrumentation was done without imaging guidance. Following screw insertion, 3D images were obtained, using an O-arm, to assess screw location.