Clinical accuracy of cervical pedicle screw insertion using lateral fluoroscopy: a radiographic analysis of the learning curve

Abstract

Cervical pedicle screw is thought to be the most stable instrumentation for reconstructive surgery of the cervical spine. However, because of the unresolved and inherent risk of neurovascular injuries due to screw perforation, it remains not widespread nowadays despite the excellent biomechanical property. Fifty-two consecutive cases having undergone spinal reconstruction using cervical pedicle screw were investigated. There were 24 females and 28 males. The mean follow-up period was 53 months. Those patients were stratified into three groups according to the period of screw insertion. A total of 280 screws were inserted. Ninety-two screws in 19 cases, 100 screws in 18 cases and 88 screws in 15 cases were inserted in the earlier, the middle and the later periods, respectively. Clinical results including complications were recorded in all cases. Screw perforations were evaluated in both plain X-ray and CT. Screw perforations occurred in 11 (12.0%), 7 (7.0%) and 1 (1.1%) screws in each period. There were no complications, such as infection, neurological deterioration and neurovascular injury directly related to screw insertion. The learning curve showed a significant improvement especially in the later period. However, the perforation rates in both the earlier and middle periods must not be underestimated. Surgeons with less experience must insert cervical pedicle screws with the assistance of a senior surgeon to avoid lethal complications.

Percutaneous instrumentation of the cervical and cervico-thoracic spine using pedicle screws: preliminary clinical results and analysis of accuracy

“…Despite its biomechanically advantages, the method is technically demanding and iatrogenic damage to neurovascular structures are feared. While lateral mass screw placement show low incidents (0-4%) of neurovascular complications [7,25,36,46], recent reports concerning CPS are promising and clinical relevant complications do not occur frequently [2,9,11,15,18,24,26,29,47,48].…”

“…The correct screw placement in other studies was defined as no pedicle perforation [11,23,47,48] or perforations up to 1 mm [15,26,29]. Screw malposition was classified as minor breach, exposure or partial perforation if the cortical breach did not extend 1.75-2 mm or encroachment of the transversal foramen up to 25% [11,15,23,26,47,48]. Critical perforations of the pedicle was assumed if the violation measured more than 1.75 to 2 mm, with dural contact or narrowing of the transversal foramen [25%.…”

“…However, none of the cortical breaches resulted in clinical symptoms and had to be revised (Group 3). Screw perforations were reported in clinical studies using anatomic landmarks and fluoroscopy in 6.7% of 669 screws [18], 6.8% of 280 screws [47], 8.6% of 93 screws [29], 13.2% of 620 screws [48] and 29% of 86 screws [23]. With the use of navigation, the reported screw deviations ranged from 1.2% of 78 screws [18], 2% of 96 screws [9], 2.8% of 178 screws [11], 3% of 176 screws [29], 10% of 116 screws [26] and 30% of 94 screws [15].…”

“…The inclination from the mid-sagittal plane was chosen according to the pedicle axis view and individual analysis of the vertebra on preoperative CT scan. The transverse angles of pedicles in the cervical spine average 40-50°in C3-C6 and 30-40°in C7 and C2 [14,27,28,31,39,47]. Additionally, the additional rotation of the vertebra due to drilling was taken into account.…”

“…However, this technique has a potential risk of nerve root, spinal cord and vertebral artery injury due to a small corridor of safe screw placement [31,39,41], recent clinical studies demonstrate that relevant complications do not occur frequently [2,9,11,15,18,24,26,29,47,48]. The axis of the cervical pedicles to the sagittal midline plane vary between 25 and 60°and makes a wide exposure of the spine necessary [14].…”