Posterior Cervical Pedicle Screw Research Articles

Feasibility and safety report on robotic assistance for cervical pedicle screw fixation: a cadaveric study

This cadaveric study aimed to evaluate the safety and usability of a novel robotic system for posterior cervical pedicle screw fixation. Three human cadaveric specimens and C2-T3 were included. Freshly frozen human cadaver specimens were prepared and subjected to robot-assisted posterior cervical pedicle screw fixation using the robotic system. The accuracy of screw placement, breach rate, and critical structure violations were evaluated. The results were statistically compared with those of previous studies that used different robotic systems for cervical pedicle screw fixation. The robotic system demonstrated a high accuracy rate in screw placement. A significant number of screws were placed within predetermined safe zones. The total entry offset was 1.08 ± 0.83 mm, the target offset was 1.86 ± 0.50 mm, and the angle offset was 2.14 ± 0.77°. Accuracy rates comparable with those of previous studies using different robotic systems were achieved. The system was also feasible, allowing precise navigation and real-time feedback during the procedure. This cadaveric study validated the safety and usability of the novel robotic system for posterior cervical pedicle screw fixation. The system exhibited high precision in screw placement, and the results support the extension of the indications for robot-assisted pedicle screw fixation from the lumbar spine to the cervical spine.

Posterior cervical pedicle screw rod short-segment internal fixation for the treatment of atlantoaxial fracture and dislocation

To investigate the clinical efficacy of posterior cervical pedicle screw short-segment internal fixation for the treatment of atlantoaxial fracture and dislocation. The clinical data of 60 patients with atlantoaxial vertebral fracture and dislocation underwent surgery between January 2015 and January 2018 were retrospectively analyzed. The patients were divided into study group and control group according to different surgical methods. There were 30 patients in study group, including 13 males and 17 females, with an average age of (39.32±2.85) years old, were underwent short-segment internal fixation with posterior cervical pedicle screws. There were 30 patients in control group, including 12 males and 18 females, with an average age of (39.57±2.90) years old, were underwent posterior lamina clip internal fixation of the atlas. The operation time, intraoperative blood loss, postoperative ambulation time, hospitalization time and complications between two groups were recorded and compared. The pain visual analogue scale(VAS), Japanese Orthopedic Association(JOA) score of neurological function, and fusion status were evaluated between two groups. All patients were followed up for at least 12 months. The study group was better than control group in operation time, intraoperative blood loss, postoperative off-bed activity time, and hospital stay (P=0.000). One case of respiratory tract injury occurred in study group. In control group, 2 cases occurred incision infection, 3 cases occurred respiratory tract injury, and 3 cases occurred adjacent segmental joint degeneration. The incidence of complications in study group was lower than that in control group (χ2=4.705, P=0.030). At 1, 3, 7 days after operation, VAS of study group was lower than that of control group(P=0.000). At 1, 3 months after operation, JOA score of study group was higher than that of control group(P=0.000). At 12 months after operation, all the patients in the study group achieved bony fusion. In control group, there were 3 cases of poor bony fusion and 3 cases of internal fixation fracture, the incidence rate was 20.00%(6/30). The difference between two groups was statistically significant (χ2=4.629, P=0.031). Posterior cervical short-segment pedicle screw fixation for atlantoaxial fracture and dislocation has the advantages of less trauma, shorter operation time, fewer complications, and less pain, and can promote the recovery of nerve function as soon as possible.

Comparison of the Safety and Efficacy of Three-Dimensional Guiding Templates and Free Hand Technique for Cervical Pedicle Screw Fixation: A Retrospective Study

Aim. To compare the safety and efficacy of computed tomography (CT)-assisted three-dimensional guiding templates (3DGTs) and free-hand (FH) technique for posterior cervical pedicle screw fixation in cervical spondylotic myelopathy (CSM) treatment. Methods. Thirty-five patients (216 screws) with CSM and developmental cervical stenosis were randomly divided into groups A (FH) and B (3DGTs). All patients underwent modified posterior surgery with cervical pedicle screw insertion (C1-7). Preoperative, postoperative, and intergroup comparisons of efficacy were evaluated using the visual analog scale (VAS), Japanese Orthopaedic Association (JOA), and Short Form 12 (SF-12) scores and JOA score improvement rate. Incidence of intra- and postoperative complications was analyzed. Postoperative cervical spine CT was performed to evaluate (i) the pedicle screws' deviation angle from the optimal path (sagittal deviation, α; coronal deviation angle, β), screw insertion point's deviation distance (d), and screw accuracy and (ii) the deviation angle and distance of screw entrance point of pedicle screws from the optimal channel. Results. All patients successfully completed the procedures. Groups A and B did not significantly differ in age, sex ratio, body mass index, operative time, or intraoperative blood loss amount. Postoperative VAS, JOA, and SF-12 scores improved in both groups. VAS, JOA, or SF-12 scores did not significantly differ between the 2 groups. The α, β, and d scores were lower in group B, but accuracy was higher in group B. Conclusions. 3DGTs and FH technique show comparable outcomes with respect to neurological improvement and safety.

Percutaneous Posterior Cervical Pedicle Instrumentation (C1 to C7) With Navigation Guidance: Early Series of 27 Cases.

Study Design:This is a technique paper describing minimally invasive, navigated, percutaneous pedicle screw fixation of the cervical spine. In addition, we include a retrospective feasibility analysis of our initial experience with 27 patients undergoing this procedure.Objective:The purpose of this study is to describe the technique of MIS navigated percutaneous cervical pedicle screw instrumentation and to report our initial experience.Methods:This is a retrospective review of 27 patients undergoing MIS navigated percutaneous posterior cervical pedicle screw fixation at 2 institutions. We describe the technique and report the radiographic outcomes and all intraoperative and postoperative complications.Results:A total of 27 patients underwent MIS navigated percutaneous pedicle screw fixation. Indications included odontoid fracture, subaxial fracture dislocations and burst fracture, pathological fracture, and degenerative spondylosis. There were no nerve root or vascular injuries. There were no spinal cord injuries. Two screws required repositioning intraoperatively, and 1 patient required reoperation for symptomatic malpositioned screw.Conclusions:MIS navigated percutaneous posterior pedicle screw fixation can be performed safely. These constructs are biomechanically superior with neurovascular complication rates comparable to traditional lateral mass screw technique. While the current indications for this technique are relatively limited, the evolution of MIS cervical decompression techniques as well as navigation and robotics will provide an expanded role for percutaneous cervical pedicle screw instrumentation.

Using the lamina nutrient foramen as the entry point for posterior cervical pedicle screw placement

Study designA prospective study and technique description. ObjectiveThis study introduced a method for posterior cervical pedicle screw placement by using the bilateral posterior lamina nutrient foramens as the entry point. MethodsFirstly, 30 dry C3-C7 vertebrae specimens were harvested for measurement. The lamina nutrient foramens were used as the entry points for posterior cervical pedicle screw placement and four linear and two angle parameters were obtained from a computed tomography scan(CT). Then, 60 patients who underwent C3–C7 pedicle screw fixation using this method were included, linear and angle parameters were obtained from a postoperative CT. ResultsThe average incidences of lamina nutrient foramen on the C3–C7 specimens were 88.3%, 90.0%, 95.0%, 95.0%, and 96.7%, respectively. The distances from the entry point to the pedicle screw tip (OD), the pedicle transverse angles (α), and the pedicle sagittal angles (β) measure for the entry points from C3–C7 were 28.74 ± 3.45–30.15 ± 2.01 mm, 26.88 ± 6.89° to 32.72 ± 5.91°, and 12.48 ± 9.31° to 19.71 ± 8.45°, respectively, with no significant differences between the left and right sides. In the 60 patients who underwent surgery, the lengths of the pedicle screws (PL) were 28.34 ± 2.25–30.15 ± 2.31 mm, the pedicle transverse angles (α) were 26.89 ± 6.86° to 32.36 ± 5.65°, and the pedicle sagittal angles (β) were 12.49 ± 9.11° to 20.06 ± 8.91°. The new method had a 96.8% (454/469) success rate among these patients, with no screws penetrating the spinal canal or signs of vertebral artery injury. ConclusionEntry at the bilateral lamina nutrient foramen represents an alternative posterior cervical pedicle screw placement technique that is feasible and safe.

Is Standalone Posterior Cervical Pedicle Screw Fixation Sufficient to Correct Cervical Postlaminectomy Kyphosis?

To evaluate the clinical processes of patients with cervical postlaminectomy kyphosis (PLK) who underwent standalone posterior pedicle screw fixation surgery. The results of 21 patients with cervical PLK treated using the pedicle screw method between 2015 and 2018 were retrospectively examined. Patient data included demographic information and indications for surgery. Furthermore, the following criteria were calculated for each patient: cervical sagittal vertical axis (cSVA), C2-7 cervical lordosis (CL) parameters, modified Japanese Orthopaedic Association (mJOA) score, Neck Disability Index (NDI) score and visual analogue scale score, and these were evaluated preoperatively and postoperatively statistically. A total of 21 patients with PLK were evaluated. In terms of radiographic parameters, postoperative cSVA was significantly lower than the preoperative cSVA, and postoperative CL was significantly higher than the preoperative CL (p < 0.001, p < 0.001, respectively). Postoperative mJOA scores were significantly higher than the preoperative scores (p < 0.001). Both postoperative NDI and VAS scores were significantly lower than the preoperative scores (p < 0.001, p < 0.001 respectively). Pedicle screw fixation was found to be an effective treatment for cervical PLK. Although this technique is not preferred by many spine surgeons because of its high complication rate, it has a positive effect on the quality of life scores and provides optimal correction.

The accuracy of a novel pedicle screw insertion technique assisted by a special angular scale in the subaxial cervical spine using lateral mass as a reference marker

BackgroundPosterior cervical pedicle screw (CPS) internal fixation has better biomechanical stability than other posterior cervical fixation methods. However, this technique is limited in clinical practice due to the complex anatomical structure and the adjacent relationship of the cervical pedicle, and the high risk of neurovascular injury. The purpose of this study was to describe a novel subaxial CPS insertion technique assisted by a special angular scale using lateral mass as a reference marker and to evaluate the accuracy of CPS placement and the distribution characteristics of CPS misplacement.MethodsA total of 36 patients with subaxial cervical spine diseases who underwent posterior CPS fixation were consecutively selected. The optimal entry point on the posterior surface of the lateral mass was identified on the three-dimensional cervical model reconstructed from preoperative computed tomography (CT) images. The pedicle transverse angle (PTA) and pedicle-lateral mass angle (PLMA) were measured on the transverse and sagittal CT images respectively. The pedicle screws were inserted according to the preoperatively planned entry point and angles. We analysed the postoperative CT images for CPS misplacement rates and perforation directions following the Lee classification.ResultsOverall, 177 pedicle screws were inserted, of which 119 (67.2%) were classified as grade 0, 43 (24.3%) as grade 1, 12 (6.8%) as grade 2 and 3 (1.7%) as grade 3 by the postoperative CT images. The accuracy rate of CPS placement was 91.5%. Of the 15 misplaced pedicle screws (grades 2 and 3), 11 were lateral pedicle perforations, 3 were superior perforations and 1 was an inferior perforation. There were no neurovascular injuries related to CPS misplacement.ConclusionsWith our technique, the optimal entry point and two angles (PTA and PLMA) were identified for CPS insertion. The novel CPS insertion technique assisted by a special angular scale provides high accuracy and few complications.

The diagnosis and management for the combination fractures of atlas and axis

Objective To investigate the treatment strategies and clinical effect of the combination fractures of atlas and axis. Methods Data of 56 cases with combination fractures of the atlas and axis treated from July 2006 to March 2014 were retrospectively analyzed. There were 36 males and 20 females with mean age of 38.6 years old (range, 21 to 63 years old). Dickman Atlantoaxial compound fracture classification: C1-II type dens fracture 21 cases, C1 fracture-atlantoaxial stability fracture 8 cases; C1 fracture-III type dens fracture 9 cases; C1 fracture-Hangman fracture 18 cases. 8 cases of C1-atlantoaxial stability fracture, 2 cases of C1-III type dens fracture and 7 cases of C1-Hangman fracture had conservative treatment and the other 39 cases were taken surgery. There were 13 patients who suffered from nerve injury such as limbs numbness, movement and the reflecting barrier before surgery: 2 Frankel B, 4 Frankel C, and 7 Frankel D. The mean preoperative JOA score was 8.6 ranging from 5.5 to 12.8. Results All patients were followed-up for a mean period of 32 months (range, 6-58 months). All the operated segments of atlas and axis showed stability and X ray showed fusion achieved within six months (average 4.5 months). Postoperative pain, upper limb numbness and neck pain were improved. 13 cases who had neurological symptoms before surgery achieved an average of 1-2 degrees of Frankel grade recovery after 6 months. The average JOA scores 6 months after operation were 14.1 ranging from 11.5 to 15.8 and the rate of improvement was 82.7% ranging from 71.5% to 95.3%. At the latest follow-up, 39 cases with surgical treatment had no complications such as fracture fixation, spinal cord injury, vertebral artery injury and cerebrospinal fluid leakage; 1 case occurred wound infection which healed after a month by debridement and dressing. Conclusion C1 fracture-III type dens fracture and stable axis fracture and stable Hangman stability fracture should be undertaken with conservative treatment. C1 fracture-II type dens fracture with atlantoodontoid interval >5 mm and unstable Hangman fracture should be treated with posterior cervical pedicle screw fixation. Occipitocervical fixation could be taken with the atlas anatomical abnormalities, severe comminuted fractures and atlas pedicle screw fixation loosening. Key words: Cervical atlas; Axis; Fractures, bone; Fracture fixation, internal

Anatomic Feasibility of Posterior Cervical Pedicle Screw Placement in Children: Computerized Tomographic Analysis of Children Under 10 Years Old

ObjectiveTo evaluate the anatomical feasibility of 3.5 mm screw into the cervical spine in the pediatric population and to establish useful guidelines for their placement.MethodsA total of 37 cervical spine computerized tomography scans (24 boys and 13 girls) were included in this study. All patients were younger than 10 years of age at the time of evaluation for the period of 2007-2011.ResultsFor the C1 screw placement, entry point height (EPH) was the most restrictive factor (47.3% patients were larger than 3.5 mm). All C2 lamina had a height larger than 3.5 mm and 68.8% (51/74) of C2 lamina had a width thicker than 3.5 mm. For C2 pedicle width, 55.4% (41/74) of cases were larger than 3.5 mm, while 58.1% (43/74) of pedicle heights were larger than 3.5 mm. For pedicle width of subaxial spine, 75.7% (C3), 73% (C4), 82.4% (C5), 89.2% (C6), and 98.1% (C7, 1/54) were greater than 3.5 mm. Mean lamina width of subaxial cervical spine was 3.1 (C3), 2.7 (C4), 2.9 (C5), 3.8 (C6), and 4.0 mm (C7), respectively. Only 34.6% (127/370) of subaxial (C3-7) lamina thickness were greater than 3.5 mm. Mean length of lateral mass for the lateral mass screw placement was 9.28 (C3), 9.08 (C4), 8.81 (C5), 8.98 (C6), and 10.38 mm (C7).ConclusionC1 lateral mass fixation could be limited by the morphometrics of lateral mass height. C2 trans-lamina approach is preferable to C2 pedicle screw fixation. In subaxial spines, pedicle screw placement was preferable to trans-lamina screw placement, except at C7.

Improvement in JOA score of treatment for complex atlas-axis fractures

The aim of this study was to explore the role of treatment for complex Atlas-Axis fractures, and compare the JOA score of surgical and conservation methods. From June 2008 to May 2012, 33 patients suffering from Atlas-Axis fracture were included in our study. Fifteen patients received posterior cervical pedicle screw fixation, and 18 patients received the conservation treatment. All the patients were followed up for 12 months after discharge. The mean operative time was about 128 minutes (ranged: 92 to 165 minutes), the mean hospital stay time was 15.5 days (ranged: 8-21 days), and the mean follow-up of all the patients was 27months (ranged: 7 to 43 months). All patients gained a solid fusion, and no one showed any disability at the end of the follow-up. The JOA scores before treatment were 6.4±0.3 and 7.1±0.4 before and after treatment, and they significantly increased to 13.8±0.8 and 13.7±0.9 when following up for 12 months (P<0.05). Posterior cervical pedicle screw fixation is a feasible, effective and safe method for complex atlantoaxial fractures. This technique could achieve high JOA score, decreased blood loss and post-operative complications.

Distractive flexion injuries of the subaxial cervical spine treated with a posterior procedure using cervical pedicle screws or a combined anterior and posterior procedure

The purpose of this study was to compare the clinical and radiographic outcomes of patients with distractive flexion (DF) injuries of the subaxial cervical spine who had undergone a posterior procedure using cervical pedicle screw (CPS) fixation with those who had undergone a combined anterior and posterior procedure. Recommendations for the surgical treatment of DF injuries of the subaxial cervical spine remain controversial. There are few clinical reports of posterior CPS fixation for DF injuries. We retrospectively reviewed the clinical records and radiographs of 50 consecutive patients with DF injuries of the subaxial cervical spine treated at the Imakiire General Hospital. Group 1 consisted of 24 patients who underwent posterior wiring fixation and fusion with additional anterior decompression and fusion. Group 2 consisted of 26 patients who underwent posterior decompression and fusion with CPS fixation. Group 1 had a significantly longer operation time (295.4minutes) than Group 2 (163.3minutes). Group 1 had significantly higher blood loss (689.1g) than Group 2 (313.7g). No patient in Group 1 or 2 developed postoperative neurological worsening. The mean loss of kyphotic correction was 1.6° and 0.1° in Groups 1 and 2, respectively, and the loss of kyphotic correction in Group 2 was significantly less than that of Group 1. We suggest that posterior procedures with CPS fixation are reasonable for the management of cervical DF injuries.

Clinical evaluation of guiding apparatus assisted individual posterior cervical pedicle screw fixation

Objective To evaluate the clinical effects of guiding apparatus assisted individual posterior cervical pedicle screw fixation technique. Methods The study enrolled 24 patients treated with posterior cervical decompressive single open-door laminoplasty and transpedicular screw-rod fixation from January 2008 to December 2010.The point of screw penetration and screw path direction were confirmed by measuring the transverse nail angle (TNA) and sagittal nail angle (SNA) of nail channel on the pre-operative CT plain scan of cervical pedicle and sagittal two-dimensional imaging of transpedicular axis.According to the results of CT measurement,individual cervical pedicle screw was implanted with the assistance of self-made guiding apparatus and then fixed after decompression.Transverse screw angle ( TSA ) and sagittal screw angle ( SSA ) were determined on the CT scan of cervical pedicle and sagittal two-dimensional imaging of transpedicular axis one week postoperatively in order to analyze the accuracy of placement of pedicle screws.Periodical anteroposterior and lateral X-ray radiographs of cervical vertebra were taken postoperatively to detect the stabilization of internal fixation. Results A total of 223 pedicle screws were inserted successfully into the C3 ～ C7,of which 220 crews were inserted accurately but three had slight inclination according to the postoperative CT,with placement accuracy of 98.7％.The comparison between inclination angle of inserted screws and that of preoperative transpedicular axis showed insignificant statistical difference ( P ＞ 0.05 ).All the patients were followed up for 6-34 months ( mean,18.5 months),which showed no neurovascular complications related to screws perforation out of pedicle cortex or no screw loosening,prolapse or breakage. Conclusion Posterior cervical pedicle screw insertionperformed according to the individual CT measurement is easy and safe and has a high accuracy rate under the assistance of self-made guiding apparatus. Key words: Cervical vertebrae; Fracture fixation, internal; Guiding apparatus

In vitro study of accuracy of cervical pedicle screw insertion using an electronic conductivity device (ATPS part III).

Reconstruction of the highly unstable, anteriorly decompressed cervical spine poses biomechanical challenges to current stabilization strategies, including circumferential instrumented fusion, to prevent failure. To avoid secondary posterior surgery, particularly in the elderly population, while increasing primary construct rigidity of anterior-only reconstructions, the authors introduced the concept of anterior transpedicular screw (ATPS) fixation and plating. We demonstrated its morphological feasibility, its superior biomechanical pull-out characteristics compared with vertebral body screws and the accuracy of inserting ATPS using a manual fluoroscopically assisted technique. Although accuracy was high, showing non-critical breaches in the axial and sagittal plane in 78 and 96%, further research was indicated refining technique and increasing accuracy. In light of first clinical case series, the authors analyzed the impact of using an electronic conductivity device (ECD, PediGuard) on the accuracy of ATPS insertion. As there exist only experiences in thoracolumbar surgery the versatility of the ECD was also assessed for posterior cervical pedicle screw fixation (pCPS). 30 ATPS and 30 pCPS were inserted alternately into the C3-T1 vertebra of five fresh-frozen specimen. Fluoroscopic assistance was only used for the entry point selection, pedicle tract preparation was done using the ECD. Preoperative CT scans were assessed for sclerosis at the pedicle entrance or core, and vertebrae with dense pedicles were excluded. Pre- and postoperative reconstructed CT scans were analyzed for pedicle screw positions according to a previously established grading system. Statistical analysis revealed an astonishingly high accuracy for the ATPS group with no critical screw position (0%) in axial or sagittal plane. In the pCPS group, 88.9% of screws inserted showed non-critical screw position, while 11.1% showed critical pedicle perforations. The usage of an ECD for posterior and anterior pedicle screw tract preparation with the exclusion of dense cortical pedicles was shown to be a successful and clinically sound concept with high-accuracy rates for ATPS and pCPS. In concert with fluoroscopic guidance and pedicle axis views, application of an ECD and exclusion of dense cortical pedicles might increase comfort and safety with the clinical use of pCPS. In addition, we presented a reasonable laboratory setting for the clinical introduction of an ATPS-plate system.

Pyogenic spondylitis in the cervicothoracic junction with high-positioned aortic arch

The authors report the case of an 87-year-old woman who suffered from T1-2 pyogenic spondylitis resulting in progressive and severe paraplegia. Debridement and anterior manubrium-splitting fusion were difficult because a high-positioned aortic arch was very close to the infectious lesion. Because adequate intravenous antibiotic agents had nearly resolved the inflammation, the authors undertook anterior debridement and posterior fusion that involved costotransversectomy and the placement of a posterior cervical pedicle screw fixation system. At 1.5 years postoperatively, there were no signs of recurrent infection. Solid osseous union was documented, and the patient's paraplegia had improved. A high-positioned aortic arch will likely interfere with an anterior approach to the cervicothoracic junction. If adequate antibiotic therapy has successfully controlled the spinal infection, anterior debridement and posterior fusion can be conducted in cases involving such anatomical limitations.