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 Table of Contents  
STUDY PROTOCOL
Year : 2016  |  Volume : 1  |  Issue : 3  |  Page : 106-111

Digital navigation enhances cervical pedicle screw placement accuracy and safety: study protocol of a randomized controlled trial


Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, China

Date of Web Publication31-Aug-2016

Correspondence Address:
Jun-jie Guan
Affiliated Hospital of Nantong University, Nantong, Jiangsu Province
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2468-5674.189509

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  Abstract 

Background: A unified standard for cervical pedicle screw placement does not currently exist; therefore, it is difficult to quantitatively evaluate the clinical effects of the technique. Digital navigation can provide a reference for accurate and safe location, orientation, and placement of cervical pedicle screws. We hypothesized that compared with partial cervical lamina excision or the pipeline-dredge discharge method, digital navigation can greatly increase the accuracy and safety of cervical pedicle screw placement.
Methods/Design: This was a prospective, single-center, randomized controlled, open-label trial. Seventy-six patients with cervical spine fracture scheduled to receive treatment in the Department of Orthopedics, Affiliated Hospital of Nantong University, China were randomly divided into three groups to undergo cervical pedicle screw internal fixation. Patients in the cervical lamina partial excision group (n = 26, 160 screws) underwent partial cervical lamina excision and cervical pedicle screw internal fixation; those in the pipeline-dredge discharge group (n = 27, 156 screws) underwent pipeline-dredge discharge and cervical pedicle screw internal fixation; and those in the digital navigation group (n = 23, 162 screws) underwent digital navigation-assisted cervical pedicle placement. All patients were evaluated at 12 and 36 months. The primary outcome was the percentage of screws graded I when evaluating the penetration degree of the cervical pedicle screws, which evaluates the accuracy of screw placement, 12 months after internal fixation. Secondary outcomes included: (1) the percentage of screws graded I when evaluating the penetration degree of cervical pedicle screws 36 months after internal fixation; (2) bony fusion rate of the atlantoaxial joint, used to evaluate fracture healing, 12 and 36 months after internal fixation; (3) Visual Analogue Scale spine score, used to evaluate cervical neck pain, prior to and 12 and 36 months after internal fixation; (4) American Spinal Injury Association Classification, used to evaluate improvement in neurological function, prior to and 12 and 36 months after internal fixation; and (5) adverse events, used to evaluate the safety of each pedicle screw implantation method, 12 and 36 months after internal fixation.
Discussion: This trial protocol compared the effects of three cervical pedicle screw internal fixation methods for the treatment of cervical spine fracture, and investigated and compared the accuracy and safety of digital navigation-assisted cervical pedicle screw placement with partial cervical lamina excision and pipeline-dredge discharge. We hoped to provide quantitative evidence for the clinical use of digital navigation in orthopedics, especially in cervical pedicle screw placement.
Trial registration: ClinicalTrial.gov identifier: NCT02880839; registered on 19 August 2016.
Ethics: This trial protocol has been approved by Medical Ethics Committee, Affiliated Hospital of Nantong University, China, and was performed in accordance with the guidelines of the Declaration of Helsinki, formulated by the World Medical Association.
Informed consent:
Signed informed consent regarding trial procedure and treatment was obtained from each patient.

Keywords: clinical trial; digital navigation; cervical spine fracture; pedicle screw; bony fusion; atlantoaxial joint; adverse reaction; partial vertebral plate excision; pipeline-dredge discharge; randomized controlled trial


How to cite this article:
Guan Jj. Digital navigation enhances cervical pedicle screw placement accuracy and safety: study protocol of a randomized controlled trial. Clin Trials Orthop Disord 2016;1:106-11

How to cite this URL:
Guan Jj. Digital navigation enhances cervical pedicle screw placement accuracy and safety: study protocol of a randomized controlled trial. Clin Trials Orthop Disord [serial online] 2016 [cited 2019 Jul 23];1:106-11. Available from: http://www.clinicalto.com/text.asp?2016/1/3/106/189509


  Introduction Top


History and current related studies

The cervical pedicle is a tiny structure adjacent to important tissues including the spinal cord and vertebral artery. Cervical pedicle screw internal fixation is the conventional treatment for cervical spine fracture (Lotfinia et al., 2010), and the technique provides acceptable internal fixation; however, current manipulation methods result in high pedicle screw penetration rates, a high risk of damage to peripheral vessels and nerves, and high rates of postoperative deformity (Lotfinia et al., 2010). Improved techniques and minimally invasive methods such as transcutaneous pedicle screw implantation have been designed to effectively reduce surgery-related injury while maintaining the accuracy and safety of pedicle screw implantation (Nakashima et al., 2009; Yoshii et al., 2016). Unfortunately, there is no unified standard regarding implantation of cervical pedicle screws, and many pedicle screw implantation methods are used including partial cervical lamina excision and pipeline-dredge discharge. However, both of these techniques are clinically limited because of poor maneuverability. Digital navigation is an emerging technique based on the discrete-accumulation principle. The technique integrates computer methods, numerical control, laser and new materials, and provides a new digital technique for confirming the location and orientation of cervical pedicle screws, ensuring safe surgical operation (Lu et al., 2009; Chen et al., 2010).

Main objective

This study aimed to compare the internal fixation results of three pedicle screw implantation methods and investigated the accuracy and safety of digital navigation-assisted pedicle screw placement.

Distinguishing features from related studies


Previous studies focused primarily on investigating the curative effects of pedicle screw implantation in cervical spine fracture. To the best of our knowledge, there are no studies of cervical spine fracture treatment by digital navigation-assisted cervical pedicle screw placement before June 2006 in Web of Science. We located two similar articles (Cervical Spondylotic Myelopathy Surgical Trial (identifier: NCT02076113) and Slotted Hole Versus Fixed Hole C-Tek (identifier: NCT00585923)) in a search of ClinicalTrials.gov up to June 2006. The outcome measures in these two studies included bony fusion Short Form 36 and the physical component score. In contrast to these two studies regarding inclusion criteria and grouping, our study was designed to investigate the accuracy and safety of digital navigation-assisted cervical pedicle screw placement, hoping to provide valuable quantitative evidence for the clinical application of this technique.


  Methods/Design Top


Study design

A prospective, single-center, randomized controlled, open-label trial.

Study setting

Affiliated Hospital of Nantong University, China.

Study procedure

Seventy-six patients with cervical fracture hospitalized in the Affiliated Hospital of Nantong University, China and scheduled to receive treatment were randomly assigned to undergo partial cervical lamina excision and cervical pedicle screw internal fixation (n = 26, 160 screws); pipeline-dredge discharge and cervical pedicle screw internal fixation (n = 27, 156 screws); or digital navigation-assisted cervical pedicle screw placement (n = 23, 162 screws). Following cervical pedicle screw internal fixation, all patients were evaluated at 12 and 36 months to assess the therapeutic effects [Figure 1].
Figure 1: Flow chart of the study protocol

Click here to view


Inclusion criteria

Patients meeting all of the following conditions were

considered for admission:

  • Fracture of the posterior column of the cervical spine or fracture of the anterior-posterior column of the cervical spine without severe vertebral body injury
  • Non-traumatic cervical lamina destabilization, including metastatic tumor and rheumatoid arthritis
  • Kyphotic deformity after cervical lamina resection
  • Segmental destabilization after nerve root or spinal cord decompression
  • Subjected to revision after anterior cervical spine surgery
  • Scheduled to undergo internal fixation by cervical pedicle screw
  • Age approximately 62 years
  • Either sex
  • Provision of signed informed consent to participate in the trial


Exclusion criteria

Patients were excluded from this trial if they presented with any of the following:

  • Cervical pedicle injury resulting from trauma or tumor
  • Severe osteoporosis
  • Anatomical variation of the vertebral artery
  • Unable or declined to proceed with internal fixation by pedicle screws
Withdrawal criteria

Patients were withdrawn from the trial if any of the following occurred:

  • Withdrawal of informed consent and refusal to continue treatment
  • Unable to undergo further treatment because of severe adverse events
  • Poor compliance during the trial
Baseline assessment

Prior to randomization, the following patient baseline data were collected: demographic data (age, sex, level of education, body mass index) and general disease history (current, previous, and genetic history).

Sample size

According to a previous report (Lang et al., 2015) and our previous clinical experience, we hypothesized that the expected percentage of screws implanted by digital navigation and graded I when evaluating the penetration depth was 92%. Sample size was calculated using PASS 14.0 software (Jerry Hintze, Kayville, UT, USA) with a level of significance of α = 0.05, ß ≤ 0.1, and power = 90%. The final effective screw sample size was determined to be n = 174 per group. Including a 20% rate of lost patients, a total of 209 screws per group were necessary: 27 patients per group. After screening for inclusion and exclusion criteria, 26, 27, and 23 patients were recruited for the partial cervical lamina excision, pipeline-dredge discharge, and digital navigation groups, respectively.

Recruitment

All patients with cervical spine fracture who received treatment in the Department of Spine Surgery, Affiliated Hospital of Nantong University, China between January 2010 and December 2012 were included in this study. After providing signed informed consent, patients were screened according to the inclusion and exclusion criteria.

Randomization

One day prior to surgery, the 76 included patients were divided into three groups according to a random sequence generated by SPSS 13.0 software (SPSS, Chicago, IL, USA) by a temporarily-arranged physician.

Blinding

This was an open trial. Physicians, patients, and assessors were not blinded to the grouping or the therapeutic regimen.

Intervention

All patients underwent internal fixation by cervical pedicle screws. Bony structures were fully exposed by dissecting the soft tissues behind the cervical spine, including muscles and ligaments. During cervical pedicle screw placement, a navigation template was closely attached to the rear of the cervical lamina. Without X-ray assistance, a 25-mm-diameter channel was drilled for screw insertion along the guiding tube of the navigation template, and screws of appropriate lengths were tapped and inserted. All screws used in the trial were made of titanium alloy (Medtronic Inc., Minneapolis, MN, USA).

  • Partial cervical lamina excision group
The cervical lamina at the segments to be fixed was partially resected until the position of the pedicle was palpated or exposed. This facilitated safe implantation of the pedicle screws without X-ray assistance.

  • Pipeline-dredge discharge group


  1. Lateral cortical bone was removed with rongeurs and cancellous bone was curetted using the rotation approach and a small curette (2.0-3.0-mm diameter) to expose the bell-shaped mouth of the pedicle canal. The cancellous bone in the pedicle canal was then carefully curetted using the small curette to expose a 3.0-5.0-mm length of the canal without X-ray assistance.
  2. If resistance was encountered, the direction of curette insertion was adjusted. If it was still not possible to insert the curette, another location was selected for screw insertion. Screws were placed in the opened pedicle canal.
  3. After establishing the screw channel, cortical screws (3.5 mm in diameter, 26.0-28.0 mm in length) were tapped. After decompression and reduction, the connective bars were installed and the nuts were tightened.


  • Digital navigation group


  1. Prior to surgery, spiral computed tomographic scans were performed, and three-dimensional reference planes were located using three-dimensional reconstruction software. The patient's cervical spine was then three-dimensionally reconstructed.
  2. Based on the reverse-engineering principle, the optimal screw insertion channel was identified, surface anatomical morphology of the cervical lamina was extracted, and a reverse template consistent with the anatomical morphology of the rear of the cervical spine was established. The reverse template and pedicle pore channel formed the location template, and models of the navigation template were made using a laser rapid-prototyping technique.
  3. Cervical spine models and the navigation template were printed using 3D-printing. Each screw channel length and pedicle width were precisely measured.
Outcome measures

Primary outcome measures


  • The percentage of screws graded I when evaluating the penetration degree of the cervical pedicle screws 12 months after internal fixation.


  1. Postoperative anterior-posterior X-ray images and computed tomographic scans were obtained to evaluate the accuracy of the cervical pedicle screw insertion for screw entry point, traveling direction, and whether screws penetrated the cortical bone.
  2. According to whether screws penetrated the pedicle and the degree of penetration, screw insertion was graded in three levels (Xie et al., 2000): grade I, pedicle screws do not penetrate the pedicular cortex; grade II, screw threads penetrate the cortex at the isthmic portion of the pedicle (no more than 1/4 length of the screw diameter); grade III, screws obviously penetrate the cortex at the isthmic portion of the pedicle (> 1/4 length of the screw diameter) with risk of peripheral nerve and vessel injury, and poor stabilization of the internal fixation.
Secondary outcome measures

  1. The percentage of screws that were graded I when evaluating the penetration degree of the cervical pedicle screws 36 months after internal fixation.
  2. The bony fusion rate of the atlantoaxial joint was used to evaluate fracture healing 12 and 36 months after internal fixation. Bone fusion rate in the atlantoaxial joint was calculated as the percentage of patients with bony fusion of the atlantoaxial joint divided by the total patient number in each group.
  3. Visual Analogue Scale spine score was used to evaluate cervical neck pain prior to and 12 and 36 months after internal fixation. The visual analogue scale spine score ranges from 0-10. Higher scores indicate more severe pain with a score of 0 indicating no pain; > 0 and ≤ 3, mild pain; > 3 and ≤ 6, moderate pain; and > 6 and ≤ 10, severe pain (Knop et al., 2001).
  4. The American Spinal Injury Association Classification was used to evaluate improvements in neurological function prior to and 12 and 36 months after internal fixation. The American Spinal Injury Association Classification includes the following categories: A: complete, no motor or sensory function is preserved in the cervical spine; B, incomplete, sensory but not motor function is preserved below the neurological level; C, incomplete, motor function is preserved below the neurological level, and more than half of the key muscles below the neurological level have a muscle grade less than 3; D, incomplete, motor function is preserved below the neurological level, and at least half of the key muscles below the neurological level have a muscle grade of 3 or more; E, normal, motor and sensory function are normal (Frankel et al., 1969).
  5. The incidence of adverse events was used to evaluate the safety of each pedicle screw implantation method 12 and 36 months after internal fixation. The incidence of adverse events was calculated as the percentage of patients developing adverse events divided by the total patient number in each group. The timing of primary and secondary outcome measure assessments is shown in [Table 1].
Table 1: Patients' baseline data and timing of primary and secondary outcome assessments

Click here to view


Adverse events

Possible adverse events included any expected or unexpected symptoms. If severe adverse events occurred, their details including the date of occurrence and measures taken to treat the adverse events were reported to the principal investigator and the institutional review board within 24 hours.

Data collection, management, analysis and open access

Data collection: Case report forms with demographic data, disease diagnosis, accompanying diseases, drug allergy history, and adverse events were collected, processed using Epidata software (Epidata Association, Odense, Denmark), collated, and then recorded electronically by data managers using a double-data entry strategy.

Data management: The locked electronic database was accessible and locked only by the project manager, and was not altered. Paper and electronic data regarding screening, informed consent, and clinical outcomes have been preserved at the Affiliated Hospital of Nantong University, China.

Data analysis: The electronic database was statistically analyzed by a professional statistician who created an outcome analysis report that was submitted to the lead researchers. An independent data monitoring committee supervised and managed the trial data, ensuring a scientific and stringent trial to yield accurate and complete data.

Data open access: Anonymized trial data was published at http://www.figshare.com.

Statistical analysis

Statistical analysis was performed by a statistician using SPSS 19.0 software (IBM Corporation, Armonk, NY, USA) and followed the intention-to-treat principle. Normally distributed measurement data was expressed as mean, standard deviation, and minimums and maximums. Non-normally distributed measurement data were expressed as lower quartile (q1), and median and upper quartile (q3). The Kruskal-Wallis H test was used to compare the visual analogue scale spine scores among the three groups, and Fisher's exact test was used to compare the degree of bony fusion of the atlantoaxial joint and the incidence of adverse reactions. P < 0.05 was considered statistically significant.

Auditing

Trial progression was reported to the ethics committee of the Affiliated Hospital of Nantong University, China every 3 months and the trial's status was updated in the registration database with each progression report.

Confidentiality

Valuable trial data was transcribed, dated, and uploaded to a dedicated computer by two staff members. Data was scheduled, checked, and locked by an investigator, password-protected, and not altered. Data regarding this trial protocol recorded on paper is preserved by the Affiliated Hospital of Nantong University, China.


  Discussion Top


Significance of this study

Findings from this trial were powered to provide quantitative evidence for the hypothesis that digital navigation can increase the accuracy and safety of cervical pedicle screw placement, which ensures safe screw placement in the treatment of cervical spine fracture.

Advantages and limitations of this study

Advantages: This study was performed via a prospective, single-blind, randomized controlled, open design and investigated the accuracy and safety of digital navigation-assisted cervical pedicle screw placement. Compared to a previous report (Lang et al., 2015), our sample size in each group was slightly larger, which increases the reliability of the trial outcomes.

Limitations: Digital navigation-assisted cervical pedicle screw placement has limited popularity in China because of the high costs of the navigation equipment, decreased accuracy caused by large range of motion of the cervical spine, complex surgical technique, low precision, long operation duration, and inconvenient sterilization. Although computer-aided navigation-assisted cervical pedicle screw placement is easy to perform without specialized experience and follows the principle of individualized cervical pedicle screw placement with high precision, it also has shortcomings including that the navigation template must be designed by a professional with experience using related computer software and expertise regarding spinal surgery. The technique is also unsuitable for patients who underwent laminectomy previously.

Evidence for contribution to future studies

Digital navigation provides a novel individualized navigation template for cervical pedicle screw placement that integrates modern radiology, three-dimensional computer reconstruction, reverse engineering, and rapid prototyping. The present study aimed to validate the hypothesis that digital navigation can assist in cervical pedicle screw placement, with a percentage of screws graded I when evaluating penetration degree of ≥ 92%, and that the technique provides high accuracy, safety, and reliability.[9]

Trial status

Data processing at the time of submission.

Conflicts of interest

None declared.

Author contributions

JJG conceived and designed the study protocol, wrote the paper and approved the final version of this paper.

Plagiarism check

This paper was screened twice using CrossCheck to verify originality before publication.

Peer review

This paper was double-blinded and stringently reviewed by international expert reviewers.


 
  References Top

1.
Chen GP, Lu S, Xu YQ, Guo H, Chen YB (2010) Application of digital navigation template to lower cervical pedicle stereotaxy. Xibei Guofang Yixue Zazhi 20:596-598.  Back to cited text no. 1
    
2.
Frankel HL, Hancock DO, Hyslop G, Melzak J, Michaelis LS, Ungar GH, Vernon JD, Walsh JJ (1969) The value of postural reduction in the initial management of closed injuries of the spine with paraplegia and tetraplegia. I. Paraplegia 7:179-192.  Back to cited text no. 2
    
3.
Knop C, Oeser M, Bastian L, Lange U, Zdichavsky M, Blauth M (2011) Development and validation of the Visual Analogue Scale (VAS) Spine Score. Unfallchirurg 104:488-497.  Back to cited text no. 3
    
4.
Lang Z, Tian W, Yuan Q, He D, Yuan N, Sun YZ (2015) Percutaneous minimally invasive pedicle screw fixation for cervical fracture using intraoperative three-dimensional fluoroscopy-based navigation. Zhonghua Waike Zazhi 53:752-756.  Back to cited text no. 4
    
5.
Lotfinia I, Sayahmelli S, Gavami M (2010) Postoperative computed tomography assessment of pedicle screw placement accuracy. Turk Neurosurg 20:500-507.  Back to cited text no. 5
    
6.
Lu S, Xu YQ, Zhang YZ, Li YB, Shi JH, Chen GP, Li DP, Fan QS (2009) Primary clinical result of digital template as navigation to upper cervical pedicle instrumentation. Zhonghua Waike Zazhi 47:359-362.  Back to cited text no. 6
    
7.
Nakashima H, Sato K, Ando T, Inoh H, Nakamura H (2009) Comparison of the percutaneous screw placement precision of isocentric C-arm 3-dimensional fluoroscopy-navigated pedicle screw implantation and conventional fluoroscopy method with minimally invasive surgery. J Spinal Disord Tech 22:468-472.  Back to cited text no. 7
    
8.
Xie N, Li JS, Jia LS (2000) Clinical anatomy and image measurement of posterior cervical spine. Dier Junyi Daxue Xuebao 21:127-130.  Back to cited text no. 8
    
9.
Yoshii T, Hirai T, Sakai K, Inose H, Kato T, Okawa A (2016) Cervical pedicle screw placement using intraoperative computed tomography imaging with a mobile scanner gantry. Eur Spine J 25:1690-1697.  Back to cited text no. 9
    


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