Computer-assisted surgery navigation of pedicle screw insertion by standardized trainees

Objective: To assess the precision and efficiency computer-assisted surgery navigation of pedicle screw insertion by standardized trainees. Methods: From September 2013 to June 2016, 360 thoracic pedicle screws were inserted into 100 patients by standardized trainees (n = 30). Screws on the left side were inserted by hands (control group), while the other side were inserted under the guidance of computer-assistant navigation system (guided group). The insertion time and volume of blood lost by each screw were retrospectively analyzed. The precision ratio was assessed by computerized tomography (CT) scan after operation. Results: The time consumed in screw insertion was significantly shorter in the guided group than that in the control group. The blood lost volume was lesser in the guided group. Post-operation CT scan revealed higher precision in the guided group than that in the control group. Conclusion: Computer-assistant navigation system facilitates the learning of standardized trainees, and reduces the time-consuming and bleeding in thoracic pedicle screw insertion.

The evaluation of long-term screw pull-out rates following posterior thoracolumbar fusion surgery with short and thin pedicle screws

Background. The aim of this study was to evaluate screw pull-out rates after fusion operations with short and thin pedicle screws.Methods. A total of 200 posterior lumbar and thoracolumbar fusion operations performed at our clinic with short and thin pedicle screws (5.5x35 mm) were retrospectively evaluated. The patients were assessed with computed tomography postoperatively on the day of surgery and at the 6th month. Single groove retraction of the transpedicular screw was evaluated as pull-out. The results were evaluated by the 'number of pull-out cases / total number of cases' and also the 'total number of pull-out screws / total number of screws used' ratios. Results. There were 112 (56%) female and 88 (44%) male patients with a mean age of 58 years. The total number of screws used in the 200 cases was 1188. There were 88 (7.4%) thoracic pedicle screws, 1056 (88.9%) lumbar pedicle screws and 44 (3.7%) sacral pedicle screws used. No pull-out was found in the control CTs taken postoperatively. Left side T11 and T12 pull-out was observed in one case and left L4 pull-out was observed in another case in the control CTs taken at the postoperative 6th month. Pull-out was observed in 2 (1%) of the 200 cases and 3 (0.25%) of the 1188 screws.Conclusions. All the short and thin pedicle screws used had passed the pedicle length and neurocentral junction. The use of a 5.5x35 mm screws in fusion operations is less invasive than using longer and thicker screws while the pull-out rates may be similar.

Cortical Bone Trajectory Screws for Fixation Across the Cervicothoracic Junction: Surgical Technique and Outcomes

Study Design: Clinical case series describing a novel surgical technique. Objective: Stabilization across the cervicothoracic junction (CTJ) poses technical difficulties which make this procedure challenging. The transition from cervical lordosis to thoracic kyphosis and the orientation of the lateral masses of the cervical spine compared with the pedicles of the thoracic spine create the need to accommodate for 2 planes of alignment when placing instrumentation. A novel surgical technique for instrumentation across the cervicothoracic junction is described. Methods: The use of cortical bone trajectory (CBT) technique for pedicle fixation in the upper thoracic spine is described in combination with cervical lateral mass or pedicle screws. The application in our first 12 patients for stabilization across the CTJ is described. Two case presentations illustrate the technique. Results: All the patients had rod screw constructs without the need to skip levels, there was no requirement for transverse connectors and only 1 plane of contouring was required. Conclusions: The use of CBT technique has not been described for the upper thoracic spine. This technique avoids many technical problems associated with posterior instrumentation of the CTJ. The facility of their use in this application arises from the similar coronal plane entry points as the cervical lateral mass screws compared with the more lateral starting point of traditional thoracic pedicle screws. The technique has clinical equipoise to traditional thoracic pedicle screw insertion but with the benefits of an easier ability to perform the instrumentation and saving levels of fusion.

Evaluation of a more ventral starting point for thoracic pedicle screws: higher maximal insertional arc and more medial and safer screw angulation

OBJECTIVETo demonstrate that a more ventral starting point for thoracic pedicle screw insertion, produced by aggressively removing the dorsal transverse process bone down to the superior articular facet (SAF), results in a larger margin for error and more medial screw angulation compared to the traditional dorsal starting point (DSP). The margin for error will be quantified by the maximal insertional arc (MIA).METHODSThe study population included 10 consecutive operative patients with adult idiopathic scoliosis who underwent primary surgery. All measurements were performed using 3D visualization software by an attending spine surgeon. The screw starting points were 2 mm lateral to the midline of the SAF in the mediolateral direction and in the center of the pedicle in the cephalocaudal direction. The DSP was on the dorsal cortex. The ventral starting point (VSP) was at the depth of the SAF. Measurements included distance to the pedicle isthmus, MIA, and screw trajectories.RESULTSTen patients and 110 vertebral levels (T1–11) were measured. The patients’ average age was 41.4 years (range 18–64 years). The pedicle isthmus was largest at T1 (4.04 ± 1.09 mm), and smallest at T5 (1.05 ± 0.93 mm). The distance to the pedicle isthmus was 7.47 mm for the VSP and 11.92 mm for the DSP (p < 0.001). The MIA was 15.3° for the VSP and 10.1° for the DSP (p < 0.001). Screw angulation was 21.7° for the VSP and 16.8° for the DSP (p < 0.001).CONCLUSIONSA more ventral starting point for thoracic pedicle screws results in increased MIA and more medial screw angulation. The increased MIA represents an increased tolerance for error that should improve the safety of pedicle screw placement. More medial screw angulation allows improved triangulation of pedicle screws.

Surgical Treatment With Thoracic Pedicle Screw Fixation of Vertebral Osteomyelitis With Long-Term Follow-up

BACKGROUND While recent data has demonstrated the utility of lumbar pedicle screws for the treatment of vertebral osteomyelitis, the data are limited for thoracic pedicle screws. OBJECTIVE To investigate the effectiveness of thoracic pedicle screws for the surgical treatment of vertebral osteomyelitis. METHODS A retrospective review of all operations performed by 2 spinal neurosurgeons from 1999 to 2012 yielded 30 cases of vertebral osteomyelitis that were treated with thoracic pedicle screws. Sixteen (53%) of which underwent combined anterior and posterior fusion and 14 patients (47%) underwent standalone posterior fusion. Postoperative records were analyzed for pertinent clinical, laboratory, and radiographic data. RESULTS Of the 30 patients, 21 were males (70%), 8 were females (27%), and 1 was transsexual (3%). The mean age was 47 yr (range 18-69). The most common organism cultured was Staphylococcus aureus in 12 cases (50%). The mean patient stay in the hospital was 12.4 d after surgery (range 5-38 d). The mean antibiotic duration after discharge was 8 wk (range 1-24 wk). Of the 25 patients with long-term follow-up (mean, 49 mo), 92% had improved back pain (6/25 marked improvement, 17/25 complete resolution), 83% had improved muscle weakness (8/18 marked improvement, 7/18 complete resolution), and 100% had improved urinary incontinence (3/8 marked improvement, 5/8 complete resolution). Two patients (7%) required additional surgical revision due to instrumentation failure or wound infection. CONCLUSION This study demonstrates the efficacy of utilizing thoracic pedicle screws as a primary intervention to treat vertebral osteomyelitis.