Subaxial Cervical Pedicular Screw Insertion via the Nonanatomic Axis: Technical Notes and Preliminary Clinical Report

Study Design: Retrospective study. Objective: To report the technical details of subaxial cervical pedicular screw insertion via the nonanatomic axis (nAA-CPS) and evaluate its clinical safety and accuracy. Methods: The nAA-CPS technique was performed in 21 patients. Preoperative and intraoperative management-related details are described, and a manipulation protocol is presented. Clinical outcomes were used to assess the safety and accuracy of screws was evaluated using postoperative computed tomography (CT) according to the pedicle perforation grading system, and the nonanatomic pedicle transverse angle (nPTA) and nonanatomic pedicle axis length (nPAL) were assessed based on pre- and postoperative CT images. Results: According to “one constant entry point (EP) and two perpendicular trajectory angles” protocol, nAA-CPS was performed without much interference from the muscles. No intraoperative or postoperative neurovascular complications related to the technique were observed. Of the 112 inserted screws, 78 (69.64%) were assessed as grade 0, 24 (21.43%) as grade 1, 4 (3.57%) as grade 2 and 6 (5.36%) as grade 3. The overall rate of correct position (grades 0 and 1) was 91.07% (102/112), and the rate of malposition was 8.93% (10/112), including five screws implanted medially and the other five laterally. The nPTA was highly consistent on pre- and postoperative CT ( P < .05), while postoperative nPAL was significantly shorter than preoperative nPAL ( P > .05). Conclusions: Clinically, the accuracy and safety of nAA-CPS was similar to the traditional CPS technique. The protocol, derived from previous radiological studies and workshops, greatly helped standardize clinical manipulation; thus, nAA-CPS is a promising alternative to the traditional CPS.

Free-Hand Cervical Pedicle Screw Placement by Using Para-articular Minilaminotomy: Its Feasibility and Novice Neurosurgeons’ Experience

Study Design.: Retrospective study. Objective.: Cervical pedicle screw (CPS) placement is technically demanding because of the great variation in pedicle size, dimension, and angulations between cervical levels and patients and the lack of anatomical landmarks. This retrospective study was conducted to analyze novice neurosurgeons’ experience of CPS placement by using the technique with direct exposure of pedicle via para-articular minilaminotomy. Methods.: We retrospectively reviewed 78 CPSs in 22 consecutive patients performed by 2 surgeons. All pedicle screws were inserted under the direct visualization of the pedicle by using para-articular minilaminotomy without any fluoroscopic guidance. We analyzed the direction and grade of pedicle perforation on the postoperative computed tomography scan. The degree of perforation was classified as grade 0 to 3. Grades 0 and 1 were classified as the correct position and the others, as the incorrect position. Results.: In total, the correct position (grade 0 and 1) was found in 72 (92.3%) screws and the incorrect position (grade 2 and 3) in 6 (7.7%). Among the 16 pedicle perforations (grade 1, 2, and 3 perforations), the directions were lateral in 15 (93.8%) and superior in 1 (6.2%). There were no neurovascular complications related to CPS insertion. Conclusion.: Free-hand CPS placement by using para-articular minilaminotomy seems to be feasible and reproducible.

Multilevel Spinal Combined Subdural/Subarachnoid Hemorrhage Resulting in Paraplegia: An Unusual Complication of Kyphoplasty

Background Paraplegia due to spinal combined subdural/subarachnoid hemorrhage is an extremely rare complication following percutaneous spinal augmentation procedures. Methods A 63-year-old male patient presented with severe neurologic decline (paraplegia with sensory and autonomic dysfunction) resulting from a multilevel spinal subarachnoid hemorrhage shortly after bilateral kyphoplasty. Results Reduction of intrathecal pressure via multiple dural and arachnoidal incisions and removal of the hematoma resulted in a good neurologic recovery with surgical decompression even though evacuation was performed with a significant delay after the onset of neurologic worsening. Conclusion Spinal augmentation procedures should only be performed in a setting where management of complications can also be diagnosed and performed. Robot-assisted or navigation-assisted pedicle perforation should be considered because complications can be reduced significantly.

Safety of Pedicle Screws in Adolescent Idiopathic Scoliosis Surgery

<p>To review existing publications on the safety of pedicle screw insertions in adolescent idiopathic scoliosis (AIS). Despite having increased risk for neurological and visceral injuries, the use of pedicle screws have led to increased correction rates in scoliosis surgery. A review was performed on topics pertinent to pedicle screw insertion in AIS, which included pedicle morphometry in AIS, structures at risk during pedicle screw insertion, and accuracy and safety of various pedicle screw insertion techniques. The importance of computer navigation and future research regarding pedicle screw placement in AIS were also briefly reviewed. Many authors have reported abnormal pedicle anatomy in AIS. Injury to the neural structures was highest over the apical region, whereas aortic injury was the highest at T5 and T10. In the proximal thoracic spine, the esophagus could be injured even with screws as short as 25 mm. Overall pedicle perforation rates for perforations &gt;0 and &gt;2 mm (assessed by computed tomography) ranged from 6.4% to 65.0% and 3.7% to 29.9%, respectively. The critical pedicle perforation (&gt;2 mm excluding lateral thoracic) and anterior perforation (&gt;0 mm) rates was reported to range from 1.5% to 14.5% and 0.0% to 16.1%, respectively. Pedicle perforation rates were lower with the use of computer navigation. The incidence of neurological adverse events after scoliosis surgery was 0.06%–1.9%. Aortic injury has only been observed in case reports. According to the available literature, pedicle screw insertion in AIS is considered safe with low rates of clinical adverse events. Moreover, the use of navigation technology has been shown to reduce pedicle perforation rates.</p>

Pedicle screw navigation: a systematic review and meta-analysis of perforation risk for computer-navigated versus freehand insertion

Object In this paper the authors' goal was to compare the accuracy of computer-navigated pedicle screw insertion with nonnavigated techniques in the published literature. Methods The authors performed a systematic literature review using the National Center for Biotechnology Information Database (PubMed/MEDLINE) using the Medical Subject Headings (MeSH) terms “Neuronavigation,” “Therapy, computer assisted,” and “Stereotaxic techniques,” and the text word “pedicle.” Included in the meta-analysis were randomized control trials or patient cohort series, all of which compared computer-navigated spine surgery (CNSS) and nonassisted pedicle screw insertions. The primary end point was pedicle perforation, while the secondary end points were operative time, blood loss, and complications. Results Twenty studies were included for analysis; of which there were 18 cohort studies and 2 randomized controlled trials published between 2000 and 2011. Foreign-language papers were translated. The total number of screws included was 8539 (4814 navigated and 3725 nonnavigated). The most common indications for surgery were degenerative disease, spinal deformity, myelopathy, tumor, and trauma. Navigational methods were primarily based on CT imaging. All regions of the spine were represented. The relative risk for pedicle screw perforation was determined to be 0.39 (p < 0.001), favoring navigation. The overall pedicle screw perforation risk for navigation was 6%, while the overall pedicle screw perforation risk was 15% for conventional insertion. No related neurological complications were reported with navigated insertion (4814 screws total); there were 3 neurological complications in the nonnavigated group (3725 screws total). Furthermore, the meta-analysis did not reveal a significant difference in total operative time and estimated blood loss when comparing the 2 modalities. Conclusions There is a significantly lower risk of pedicle perforation for navigated screw insertion compared with nonnavigated insertion for all spinal regions.

Cement Leakage into the Posterior Spinal Canal during Balloon Kyphoplasty: A Case Report

We report a case of cement leakage into the posterior spinal canal due to inadvertent pedicle perforation during balloon kyphoplasty. The leakage was corrected immediately without any sequelae. Features seen on radiography and the minimally invasive procedure used for removal are described. The postoperative radiographs of 100 consecutive patients treated with balloon kyphoplasty were subsequently reviewed. Only one patient had a similar leakage but had no neurological complications.

Cervical pedicle screw fixation in 100 cases of unstable cervical injuries: pedicle axis views obtained using fluoroscopy

Object The authors conducted a study to introduce the imaging technique in which pedicle axis views are obtained using fluoroscopy to match the screw entry point with pedicle orientation and to report the clinical results and safety of cervical pedicle screw fixation (PSF) in patients treated for unstable cervical injuries. Methods One hundred consecutive patients with unstable cervical injuries underwent PSF in which the authors used fluoroscopic imaging to acquire pedicle axis views. There were 87 men and 13 women whose mean age was 42.5 years. The accuracy of PS placement was examined postoperatively using axial computed tomography (CT) and oblique radiography. Screw malpositioning was classified either as screw exposure (< 50% of the screw outside the pedicle) or pedicle perforation (> 50% of the screw outside the pedicle boundaries). The mean operative time was 97.6 minutes, and the mean estimated blood loss was 221 ml. Local vertebral alignment around the injured segment measured 6.0° of kyphosis preoperatively and 6.7° of lordosis postoperatively. Solid posterior bone fusion was achieved in all but three patients who died shortly after surgery. There was no secondary dislodgment of instrumentation in 95% of these 97 cases. Of the 419 cervical PSs, 43 (10.3%) were of the screw-exposure type and 17 (4.0%) of the pedicle-perforation type. There were two surgery-related complications: one penetration of a probe into the vertebral artery and one radiculopathy. There were six postoperative complications: two cases of instrumentation failure associated with loss of correction, three cases of correction loss (> 10°), and one case of deep wound infection. Conclusions Solid posterior fusion without secondary dislodgment of hardware was demonstrated in 95% of the cases. The incidence of complications associated with cervical PSF was not high. Postoperative CT scanning showed that 17 (4.0%) of 419 screws perforated the pedicle. It appears that fluoroscopy performed using pedicle axis views improves the accuracy and safety of cervical PS insertion.