|Year : 2017 | Volume
| Issue : 4 | Page : 390-395
Easy method to simplify “freehand” subaxial cervical pedicle screw insertion
Alexander V Burcev1, Olga M Pavlova1, Konstantin A Diachkov1, Galina V Diachkova1, Sergey O Ryabykh2, Alexander V Gubin1
1 Russian Ilizarov Scientific Center, Kurgan, Russian
2 Division Spine Pathology and Rare Diseases, Russian Ilizarov Scientific Center, Kurgan, Russian
|Date of Web Publication||19-Dec-2017|
Dr. Olga M Pavlova
Russian Ilizarov Scientific Center, Kurgan
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Study Design: Technical note.
Objectives: The objective of this study is to check out safety and rationality of standardized and fast tricks to select trajectory of subaxial cervical pedicle screw (SCPS) insertion, based on simple angles to bony landmarks.
Materials and Methods: Stage 1 – Computed tomography (CT)-morphometric analysis of C3–C7 vertebrae of ten patients with cervical degenerative diseases. Stage 2 – SCPS insertion in 6 cadavers, according to the developed technique (59 pedicle screws). Stage 3 – SCPS insertion in 6 patients, according to the developed technique (32 pedicle screws).
Results: CT-morphometric analysis showed that the average length of C3–C7 pedicle channels was 32 mm, the average angle between a pedicle axis and an axis of contralateral lamina - 180°, the average angle between a pedicle axis and plane of a posterior surface of a lateral mass amounted to 90° and the coordinates of an optimal entry point – 2 mm from a lateral edge and 2 mm from an upper edge of the lateral mass posterior surface. During the cadaveric study, 39 screws had a satisfactory position (66.1%), 7 screws permissible (11.9%), and 13 screws unacceptable (22%). During the clinical study, 26 screws (81.25%) had satisfactory position, 4 (12.5%) had permissible position, and 2 (6.25%) unacceptable position.
Conclusion: Developed and clinically approved a method for simplicity SCPS insertion is relatively safe and cheap. No doubt, it requires further investigation, but the results of primary analysis allow us to recommend it to wide practical application.
Keywords: “Freehand” pedicle screw, subaxial pedicle screw fixation, screw insertion technique
|How to cite this article:|
Burcev AV, Pavlova OM, Diachkov KA, Diachkova GV, Ryabykh SO, Gubin AV. Easy method to simplify “freehand” subaxial cervical pedicle screw insertion. J Craniovert Jun Spine 2017;8:390-5
|How to cite this URL:|
Burcev AV, Pavlova OM, Diachkov KA, Diachkova GV, Ryabykh SO, Gubin AV. Easy method to simplify “freehand” subaxial cervical pedicle screw insertion. J Craniovert Jun Spine [serial online] 2017 [cited 2019 Oct 16];8:390-5. Available from: http://www.jcvjs.com/text.asp?2017/8/4/390/221122
| Introduction|| |
Unstable cervical spine requires spondylodesis using fixation tools. A great amount of publications about subaxial cervical pedicle screw (SCPS) fixation shows the high popularity of this method. However, almost each clinical study indicates a high risk of the neurovascular injury that explains the high number of tricks, proposed for SCPS insertion. Most of these methods are individualized. We would like to introduce a standardized and fast method for SCPS: Screw insertion based on the simple angles to the bony landmarks. The protocol was approved by Ethics Committee of the Hospital and informed consent of patients who were surgically treated was received.
| Materials and Methods|| |
This study consists of three stages, measurements at all three stages were performed by the same radiologist with the assistance of the same spinal surgeon, who performed screw insertion on the second and third stages.
Stage 1 – CT-morphometric analysis of C3–C7 vertebrae of 10 patients 38–64-year-old with cervical degenerative diseases (50 vertebrae and 100 pedicles).
A 64-slice multidetector CT scanner (Aquilion, Toshiba, GE Light Speed, Neck Standard program, Helical) with a gantry rotation speed of 0.5 s per rotation was used. Slice thickness of 3 mm, reconstruction interval of 3 mm, tube voltage of 120 kV, and tube current of 175 mA were used for scanning. CT was carried out on supine position: In the neutral position of a head, and after that in maximum right- and left-side head tilts. Coronal and sagittal multiplanar images were reconstructed. The morphometric parameters of the pedicles were measured on images of multiplanar reformations. Measurements of each subaxial vertebra included four marks: angle between the pedicle axis and the axis of contralateral lamina [Figure 1]; angle between the pedicle axis and plane of the lateral mass posterior surface [Figure 2]; the coordinates of optimal entry point for SCPS-the distance from the lateral edge and from the upper edge of the lateral mass posterior surface; and the length of the pedicle channel (for bicortical screw insertion).
|Figure 1: Angle between the pedicle axis and the axis of contralateral lamina|
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|Figure 2: Angle between the pedicle axis and plane of the lateral mass posterior surface|
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Stage 2 – Cadaveric study (6 cadavers and 59 pedicle screws): SCPS insertion through the mean optimal entry point (2 mm from the lateral edge and from the upper edge of the lateral mass posterior surface) according to two found standard angles (parallel to the lamina axis and perpendicular to the posterior surface of the lateral mass) in C3-C7 vertebrae of 6 cadavers. The cadaveric operations were carried out from the posterior approach by one surgeon, without preoperative CT. We used 3.5 mm × 25 mm and 3.5 mm × 30 mm screws. After insertion of screws, all operated vertebrae were carefully extracted from cadavers, and CT scan was done to perform the analysis of screw courses. Evaluation of the position of the screw was assessed as satisfactory when the screw was completely in a pedicle, permissible when a screw malposition was 1 mm and less in a radicular or spinal canal and if a vertebral artery canal overlapping was <25%, unacceptable when the screw malposition was more than 1 mm in a radicular or spinal canal and if a vertebral artery canal overlapping was more than 25%.,
Stage 3 – Clinical study (6 patients and 32 pedicle screw): SCPS insertion based on the simple angles to the bony landmarks by the same surgeon as in the cadaveric study. Three patients had traumatic injuries, one patient had rheumatoid lesions, and two patients had degenerative spinal stenosis.
| Results|| |
Stage 1 – CT measurement results are shown in [Table 1]. The average length of a pedicle channel of the C3–C7 vertebrae in ten patients was 32 mm. The average angle between a pedicle axis and an axis of contralateral lamina of a vertebra was 180°. The average angle between a pedicle axis and plane of a posterior surface of a lateral mass amounted to 90°. The coordinate of an optimal entry point – 2 mm from a lateral edge and 2 mm from an upper edge of the lateral mass posterior surface.
|Table 1: Computed tomography-morphometric analysis of the C3-C7 vertebrae of 10 patients 38-64-year-old with cervical degenerative diseases (50 vertebrae, 100 pedicles)|
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Based on these data, we suggest the following simple method of SCPS insertion: optimal entry point is located 2 mm from the lateral edge and 2 mm from the upper edge (or joint plane) of the lateral mass posterior surface [Figure 3]; the horizontal plane trajectory is parallel to a contralateral lamina axis of the same vertebra [Figure 4]; and the sagittal plane trajectory is perpendicular to a lateral mass posterior surface.
Stage 2 – During the cadaveric study, 59 screws were inserted in C3 to C7 pedicles: Thirty-nine screws had satisfactory position (66.1%), 7 screws permissible (11.9%), and 13 screws unacceptable (22%) [Figure 5]. Intraoperative fluoroscopy was not used.
|Figure 5: Position of the subaxial cervical pedicle screw on the postoperative computed tomography in the cadaveric study (59 screws)|
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Stage 3 – The new method of SCPS insertion was applied to 6 patients, 32 screws were introduced using this method (preoperative CT and intraoperative fluoroscopy were used). Postoperative CT showed that 26 screws (81.25%) had a satisfactory position, 4 (12.5%) had permissible position, and 2 (6.25%) unacceptable position [Figure 6]. In all cases, screw malpositions were asymptomatic. CT angiography in 2 cases with unacceptable screw position determined vertebral arteries stenosis with a stored blood flow, these screws were removed. There were no other intraoperative and early postoperative complications. The average volume of bleeding during operations was 316.6 ± 211.34 ml. The average duration of the operation was 175 ± 65.7 min.
|Figure 6: Position of the subaxial cervical pedicle screw on the postoperative computed tomography in the clinical application on six patients: (a-c) Satisfactory position, (d and e) permissible position, (f) unacceptable position|
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| Discussion|| |
The concept of SCPS insertion was proposed by Abumi et al. Pedicle screw fixation in the cervical spine due to three column stabilization provides significantly greater rigidity compared with lateral mass screw fixation,,,, this is most important in cases of poor bone quality. Numerous biomechanical studies show the reliability of the SCPS fixation,,,, nevertheless many authors note high risk of neurovascular injury.,,,,,, The wide variability of pedicle size in cervical region complicates the choice of standard bony landmarks, necessary to determine the optimal screw entry point.,, According to the anthropometric data the “safest” vertebrae for SCPS are C6 and C7, due to the larger diameter of pedicles,,,,,,, besides, more than 95% of C7 vertebrae do not contain a vertebral artery. “Most dangerous” vertebrae for SCPS are C3–C5, the risk of neurovascular injury is much higher due to smaller diameter and steep slope of axis of the pedicle.,,,,,, In general, the method of SCPS insertion is recommended for application by experienced surgeons.,,
The usage of navigational systems and laminoforaminotomy reduces the risk of malposition.,,,,,,,,,,,,,,,, Comparison of three insertion techniques (anatomical landmarks, laminoforaminotomy, and computer-assisted navigation) showed that the critical malposition accounted for 65.6%, 39.6%, and 10.6%, respectively. However, other authors determined that the risk of screw malposition in the computer-assisted navigation is higher than without it,, perhaps due to the fact that CT-based navigation cannot provide real-time navigation and intraoperative changes of spinal alignment can appear during the patient positioning, flexion or extension, rotation, and torsion of the neck. Besides, the high cost of navigation equipment, as well as the duration of its setting, limits its usage. The conception of navigation template systems has been reported by several authors and reduced screw malposition risk up to zero.,
Large number of articles devoted to SCPS show us different variants of the “freehand” method,,, the screw insertion angle varies from 35° to 50°.,,,,,,, However, intraoperative selection of the screw insertion angle is difficult, and slightest deviation can cause screw malposition.,,,,,, Therefore, in this study, we tried to develop a method of SCPS insertion, based on usage of simple angles (90° and 180°) to bony landmarks, which should reduce the number of screw malposition, the duration and cost of the operation.
Another important aspect of SCPS insertion is the choice of the entry point, which varies on different levels. Anthropometric measurements obtained in this study indicate the possibility of standardizing methods of SCPS insertion: Entry point coordinates can be identified using the so-called “rule of two” (2 mm from the lateral edge and 2 mm from the upper edge of the lateral mass posterior surface). The trajectory of the insertion in the horizontal plane parallel to the contralateral lamina axis of the same vertebra, the sagittal plane trajectory perpendicular to the lateral mass posterior surface, the screw length 30–32 mm. It should be noted that the bony landmarks for SCPS insertion can be used only if the preoperative CT showed the normal vertebral anatomy.,,, In all other cases, additional methods of SCPS positioning should be used (three-dimensional guide,, laminoforaminotomy) or other fixation techniques (lateral mass screw, interlaminar screw, and transarticular screw).
Fatal or invalidating neurovascular injuries during the SCPS insertion are described only in a few papers., The present study has limitations:First, the proposed method does not eliminate the risk of screw malposition and secondly, a small cohort of people in the study. However, we revealed patterns that can have practical value. Further research work should study possible difficulties in this method usage.
| Conclusion|| |
Developed and clinically approved method of SCPS insertion is relatively safe and cheap. No doubt, it requires further investigation, but the primary analysis allows us to recommend it to wide practical application.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Kast E, Mohr K, Richter HP, Börm W. Complications of transpedicular screw fixation in the cervical spine. Eur Spine J 2006;15:327-34.
Ando K, Imagama S, Ito Z, Kobayashi K, Ukai J, Muramoto A, et al.
Unilateral instrumented fixation for cervical dumbbell tumors. J Orthop Surg Res 2014;9:2.
Abumi K, Itoh H, Taneichi H, Kaneda K. Transpedicular screw fixation for traumatic lesions of the middle and lower cervical spine: Description of the techniques and preliminary report. J Spinal Disord 1994;7:19-28.
Kothe R, Rüther W, Schneider E, Linke B. Biomechanical analysis of transpedicular screw fixation in the subaxial cervical spine. Spine (Phila Pa 1976) 2004;29:1869-75.
Bayley E, Zia Z, Kerslake R, Boszczyk BM. The ipsilateral lamina-pedicle angle: Can it be used to guide pedicle screw placement in the sub-axial cervical spine? Eur Spine J 2010;19:458-63.
Dunlap BJ, Karaikovic EE, Park HS, Sokolowski MJ, Zhang LQ. Load sharing properties of cervical pedicle screw-rod constructs versus lateral mass screw-rod constructs. Eur Spine J 2010;19:803-8.
Ludwig SC, Kramer DL, Vaccaro AR, Albert TJ. Transpedicle screw fixation of the cervical spine. Clin Orthop Relat Res 1999;(359):77-88.
Schmidt R, Wilke HJ, Claes L, Puhl W, Richter M. Pedicle screws enhance primary stability in multilevel cervical corpectomies: Biomechanical in vitro
comparison of different implants including constrained and nonconstrained posterior instumentations. Spine (Phila Pa 1976) 2003;28:1821-8.
Desai S, Sethi A, Ninh CC, Bartol S, Vaidya R. Pedicle screw fixation of the C7 vertebra using an anteroposterior fluoroscopic imaging technique. Eur Spine J 2010;19:1953-9.
Nakashima H, Yukawa Y, Imagama S, Kanemura T, Kamiya M, Yanase M, et al.
Complications of cervical pedicle screw fixation for nontraumatic lesions: A multicenter study of 84 patients. J Neurosurg Spine 2012;16:238-47.
Huang D, Du K, Zeng S, Gao W, Huang L, Su P, et al.
The security analysis of transpedicular screw fixation in the lower cervical spine and a case report. Spine (Phila Pa 1976) 2011;36:E1702-8.
Tofuku K, Koga H, Komiya S. Cervical pedicle screw insertion using a gutter entry point at the transitional area between the lateral mass and lamina. Eur Spine J 2012;21:353-8.
Kotil K, Akçetin MA, Savas Y. Neurovascular complications of cervical pedicle screw fixation. J Clin Neurosci 2012;19:546-51.
Yukawa Y, Kato F, Ito K, Horie Y, Hida T, Nakashima H, et al.
Placement and complications of cervical pedicle screws in 144 cervical trauma patients using pedicle axis view techniques by fluoroscope. Eur Spine J 2009;18:1293-9.
Abumi K, Shono Y, Ito M, Taneichi H, Kotani Y, Kaneda K, et al.
Complications of pedicle screw fixation in reconstructive surgery of the cervical spine. Spine (Phila Pa 1976) 2000;25:962-9.
Herrero CF, Luis do Nascimento A, Maranho DA, Ferreira-Filho NM, Nogueira CP, Nogueira-Barbosa MH, et al.
Cervical pedicle morphometry in a latin american population: A Brazilian study. Medicine (Baltimore) 2016;95:e3947.
Yusof MI, Ming LK, Abdullah MS. Computed tomographic measurement of cervical pedicles for transpedicular fixation in a malay population. J Orthop Surg (Hong Kong) 2007;15:187-90.
Yusof MI, Ming LK, Abdullah MS, Yusof AH. Computerized tomographic measurement of the cervical pedicles diameter in a malaysian population and the feasibility for transpedicular fixation. Spine (Phila Pa 1976) 2006;31:E221-4.
Oh SH, Min WK. Analysis of cervical pedicle with reconstructed computed tomography imaging in korean population: Feasibility and surgical anatomy. J Spinal Disord Tech 2014;27:E99-E103.
Cho W, Eid AS, Chang UK. The use of pedicle screw-rod system for the posterior fixation in cervico-thoracic junction. J Korean Neurosurg Soc 2010;48:46-52.
Yoshimoto H, Sato S, Hyakumachi T, Yanagibashi Y, Kanno T, Masuda T, et al.
Clinical accuracy of cervical pedicle screw insertion using lateral fluoroscopy: A radiographic analysis of the learning curve. Eur Spine J 2009;18:1326-34.
Richter M, Cakir B, Schmidt R. Cervical pedicle screws: Conventional versus computer-assisted placement of cannulated screws. Spine (Phila Pa 1976) 2005;30:2280-7.
Ludwig SC, Kowalski JM, Edwards CC 2nd
, Heller JG. Cervical pedicle screws: Comparative accuracy of two insertion techniques. Spine (Phila Pa 1976) 2000;25:2675-81.
Hong JT, Tomoyuki T, Udayakumar R, Espinoza Orías AA, Inoue N, An HS, et al.
Biomechanical comparison of three different types of C7 fixation techniques. Spine (Phila Pa 1976) 2011;36:393-8.
Rajasekaran S, Kanna PR, Shetty AP. Safety of cervical pedicle screw insertion in children: A clinicoradiological evaluation of computer-assisted insertion of 51 cervical pedicle screws including 28 subaxial pedicle screws in 16 children. Spine (Phila Pa 1976) 2012;37:E216-23.
Lee SH, Kim KT, Suk KS, Lee JH, Son ES, Kwack YH, et al.
Assessment of pedicle perforation by the cervical pedicle screw placement using plain radiographs: A comparison with computed tomography. Spine (Phila Pa 1976) 2012;37:280-5.
Reinhold M, Magerl F, Rieger M, Blauth M. Cervical pedicle screw placement: Feasibility and accuracy of two new insertion techniques based on morphometric data. Eur Spine J 2007;16:47-56.
Zhou F, Zou J, Gan M, Zhu R, Yang H. Management of fracture-dislocation of the lower cervical spine with the cervical pedicle screw system. Ann R Coll Surg Engl 2010;92:406-10.
Uehara M, Takahashi J, Ogihara N, Hirabayashi H, Hashidate H, Mukaiyama K, et al.
Cervical pedicle screw fixation combined with laminoplasty for cervical spondylotic myelopathy with instability. Asian Spine J 2012;6:241-8.
Kotani Y, Abumi K, Ito M, Minami A. Cervical spine injuries associated with lateral mass and facet joint fractures: New classification and surgical treatment with pedicle screw fixation. Eur Spine J 2005;14:69-77.
Richter M, Amiot LP, Neller S, Kluger P, Puhl W. Computer-assisted surgery in posterior instrumentation of the cervical spine: An in-vitro
feasibility study. Eur Spine J 2000;9 Suppl 1:S65-70.
Reinhold M, Bach C, Audigé L, Bale R, Attal R, Blauth M, et al.
Comparison of two novel fluoroscopy-based stereotactic methods for cervical pedicle screw placement and review of the literature. Eur Spine J 2008;17:564-75.
Kantelhardt SR, Bock HC, Siam L, Larsen J, Burger R, Schillinger W, et al.
Intra-osseous ultrasound for pedicle screw positioning in the subaxial cervical spine: An experimental study. Acta Neurochir (Wien) 2010;152:655-61.
Ludwig SC, Kramer DL, Balderston RA, Vaccaro AR, Foley KF, Albert TJ, et al.
Placement of pedicle screws in the human cadaveric cervical spine: Comparative accuracy of three techniques. Spine (Phila Pa 1976) 2000;25:1655-67.
Lu S, Xu YQ, Lu WW, Ni GX, Li YB, Shi JH, et al.
A novel patient-specific navigational template for cervical pedicle screw placement. Spine (Phila Pa 1976) 2009;34:E959-66.
Kaneyama S, Sugawara T, Sumi M. Safe and accurate midcervical pedicle screw insertion procedure with the patient-specific screw guide template system. Spine (Phila Pa 1976) 2015;40:E341-8.
Ma W, Xu R, Liu J, Sun S, Zhao L, Hu Y, et al.
Posterior short-segment fixation and fusion in unstable hangman's fractures. Spine (Phila Pa 1976) 2011;36:529-33.
Sakamoto T, Neo M, Nakamura T. Transpedicular screw placement evaluated by axial computed tomography of the cervical pedicle. Spine (Phila Pa 1976) 2004;29:2510-4.
Lee DH, Lee SW, Kang SJ, Hwang CJ, Kim NH, Bae JY, et al.
Optimal entry points and trajectories for cervical pedicle screw placement into subaxial cervical vertebrae. Eur Spine J 2011;20:905-11.
Zheng X, Chaudhari R, Wu C, Mehbod AA, Transfeldt EE. Subaxial cervical pedicle screw insertion with newly defined entry point and trajectory: Accuracy evaluation in cadavers. Eur Spine J 2010;19:105-12.
Abumi K. Cervical spondylotic myelopathy: Posterior decompression and pedicle screw fixation. Eur Spine J 2015;24 Suppl 2:186-96.
Tian W, Weng C, Liu B, Li Q, Hu L, Li ZY, et al.
Posterior fixation and fusion of unstable Hangman's fracture by using intraoperative three-dimensional fluoroscopy-based navigation. Eur Spine J 2012;21:863-71.
Lee SH, Kim KT, Abumi K, Suk KS, Lee JH, Park KJ, et al.
Cervical pedicle screw placement using the “key slot technique”: The feasibility and learning curve. J Spinal Disord Tech 2012;25:415-21.
Zhang PX, Xue F, Zhang DY, Fu ZG, Han N, Kou YH, et al.
Positioning study of cervical vertebra pedicle axial line projective point by computed tomography image reconstruction. Chin Med J (Engl) 2012;125:2521-4.
Patwardhan AR, Nemade PS, Bhosale SK, Srivastava SK. Computed tomography-based morphometric analysis of cervical pedicles in indian population: A pilot study to assess feasibility of transpedicular screw fixation. J Postgrad Med 2012;58:119-22. [Full text]
Kim MK, Cho SM, You SH, Kim IB, Kwak DS. Hybrid technique for cervical pedicle screw placement: Combination of miniopen surgery and use of a percutaneous cannula system-pilot study. Spine (Phila Pa 1976) 2015;40:1181-6.
Schaefer C, Begemann P, Fuhrhop I, Schroeder M, Viezens L, Wiesner L, et al.
Percutaneous instrumentation of the cervical and cervico-thoracic spine using pedicle screws: Preliminary clinical results and analysis of accuracy. Eur Spine J 2011;20:977-85.
Onishi E, Sekimoto Y, Fukumitsu R, Yamagata S, Matsushita M. Cerebral infarction due to an embolism after cervical pedicle screw fixation. Spine (Phila Pa 1976) 2010;35:E63-6.
[Figure 1], [Figure 2], [Figure 4], [Figure 3], [Figure 5], [Figure 6]