The Subaxial Cervical Pedicle Screw for Cervical Spine Diseases: The Review of Technical Developments and Complication Avoidance

Abstract

This study aimed to review information on the subaxial cervical pedicle screw (CPS) including recent anatomical considerations, entry points, placement techniques, accuracy, learning curve, and complications. Relevant literatures were reviewed, and the authors' experiences were summarized. The CPS is used for reconstruction of unstable cervical spine and achieves superior biomechanical stability compared to other fixation techniques. Various insertion and guidance techniques are established, among which, lateral fluoroscopy-assisted placement is the most common and cost-effective technique. Generally, placement under imaging guidance is more accurate than other techniques, and a threedimensional template allows optimal trajectory for each pedicle regardless of intraoperative changes in spinal alignment. The free-hand technique using a curved pedicle probe without a funnel-like hole increases screw stability and reduces operation time, radiation exposure, and soft tissue injury. Compared to conventional lateral fluoroscopy-assisted placement, free-hand CPS placement by trained surgeons achieves superior accuracy comparable to that of image-guided navigation; in general, 30 training cases are sufficient for learning a safe and accurate technique for CPS placement. The complications of subaxial CPS are classified into three categories: complications due to screw misplacement, complications without screw misplacement, and others. Inexperienced surgeons may benefit from advanced techniques; however, the accuracy of CPS ultimately depends on the surgeon's experience. Inexperienced surgeons should master the placement of the thoracolumbar pedicle screw in real practice and practice CPS insertion using cadavers. During the initial phase of the learning curve, careful preparation of surgery, reiterated identification, patterned safety steps, and supervision of the expert are necessary.

Cervical Spine Pedicle Screw Accuracy in Fluoroscopic, Navigated and Template Guided Systems—A Systematic Review

“…Pedicle screw insertion in the cervical spine is complicated by the smaller pedicle widths, the larger transverse pedicle angles and the proximity of the vertebral arteries, nerve roots and spinal cord. Factors affecting anatomy include gender, age, height and race [ 6 ]. Figure 1 shows a post-operative axial CT image of a patient who underwent cervical spine pedicle screw fixation with a fatal injury to the vertebral artery.…”

“…Figure 1 shows a post-operative axial CT image of a patient who underwent cervical spine pedicle screw fixation with a fatal injury to the vertebral artery. Several authors have converged on the 4 mm pedicle width as the smallest sized pedicle that would be appropriate for pedicle screws [ 5 , 6 , 22 ]. The thickness of soft tissues over the posterior neck must also be considered—thick muscle and fat has been suggested to be a greater cause of pedicle wall violation than pedicle diameter [ 6 ].…”

“…Pedicle screws provide excellent biomechanical stability throughout the spine; however, its use in the cervical spine is limited by the technical challenges of instrumenting the narrow, oblique pedicles, and the risk of damage to the vertebral arteries [ 1 , 2 , 3 , 4 ]. To overcome these challenges, Abumi demonstrated the safe use of cervical pedicle screws inserted using a combination of freehand and lateral fluoroscopic guidance, which has become the standard for cervical pedicle screw placement, but this is not without technical hurdles [ 5 , 6 , 7 ]. Despite familiarity with the technique, the incidence of neurovascular complications due to screw placement with fluoroscopic guidance in the cervical spine has been estimated to be as low as 0.4%, although the consequences of these infrequent events can lead to paraplegia, cerebral infarct and death in severe cases [ 1 , 8 , 9 ].…”

“…More recently, 3D printing has advanced and has found application in medicine; pre-operative imaging creates computerised models of the vertebrae, and 3D templates are designed which fit onto the posterior surface of the vertebrae, with screw guides that guide the direction of the screws along the trajectory of the pedicle. This negates the need for intraoperative imaging; however, the bespoke nature of the templates means time is needed to model, print and distribute them and it is not appropriate for use in cases where there is no lead time (such as in emergent surgery) [ 4 , 6 , 14 , 15 ].…”

Posterior Facetectomy with Fusion Using a Pedicle Screw for Parallel-shaped Cervical Foraminal Stenosis

“…We previously showed the efficacy and safety of placing a large series of cervical pedicle screws (CPSs) in patients with severe pathology of the cervical spine. 3 6 12 15 16 17 19 20 21 24) To date, there are no reports regarding the treatment of severe cervical FS by PF using FPS. In this study, we demonstrate the efficacy and safety of posterior facetectomy with fusion using pedicle screw (PF using FPS) to treat parallel-shaped severe cervical FS.…”