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

Abstract

The pedicle screw instrumentation represents the most rigid construct of the cervical and cervicothoracic spine and in spite of the risks to neurovascular structures clinical relevant complications do not occur frequently. The steep angles of the cervical pedicles result in a wide surgical exposure with extensive muscular trauma. The objective of this study was the evaluation of the accuracy of cervical pedicle screw insertion through a minimally invasive technique to reduce access-related muscular trauma. Therefore, percutaneous transpedicular instrumentation of the cervical and cervicothoracic spine was performed in 15 patients using fluoroscopy. All instrumentations from C2 to Th4 were inserted bilaterally through 2 to 3-cm skin and fascia incisions even in multilevel procedures and the rods were placed by blunt insertion through the incision. Thin-cut CT scan was used postoperatively to analyze pedicle violations. 76.4% of 72 screws were placed accurately. Most pedicle perforations were seen laterally towards the vertebral artery. Critical breaches >2 mm or narrowing of the transversal foramen occurred in 12.5% of screws; however, no revision surgery for screw displacement was needed in the absence of clinical symptoms. No conversion from percutaneous to open surgery was necessary. It was concluded that percutaneous transpedicular instrumentation of the cervical spine is a surgically demanding technique and should be reserved for experienced spine surgeons. The indications are limited to instrumentation-only procedures or in combination with anterior treatment, but with the potential to minimize access-related morbidity.

Fig. 1

a A 73-year-old male with cervicothoracic instability due to osteolysis of C3, C5 and Th1. b No compression of the spinal cord was present as shown by presurgical MRI (T1). c A percutaneous stabilization C2 to Th3 was performed. d Postsurgical photograph of surgical approach. A 2–3 cm incision of skin and fascia was sufficient for instrumentation of 2–3 adjacent levels with rod insertion

Fig. 2

Intraoperative correction of screw position in C2. a Axial and b coronal view of multiplanar reconstruction obtained by isocentric C-arm after drill insertion. A clear displacement of the drill perforating the medial pedicle wall could be identified. c Axial and d coronal view of reconstructed images after correction of drill position. e Axial and f coronal view of postoperative CT scan showing correct screw placement

Fig. 3

a and b A 79-year-old male (patient 9) with incomplete tetraparesis (Frankel grade C) due to spondylodiscitis C3/C4 with epidural abscess from C2 to C4. He was treated with anterior corpectomy C3/C4, vertebral body replacement and anterior plating C2-C5. c and d Additional posterior stabilization was performed percutaneously C2-C5 to improve construct rigidity. An anterior revision surgery was necessary due to persistent deep tissue infection. At discharge from hospital neurologic symptoms were markedly improved (Frankel grade D)

Fig. 4

Limitations to intraoperative verification of correct screw placement after anterior vertebral body replacement of C3 with plating and percutaneous posterior transpedicular instrumentation of C2 to C4. a Axial view of multiplanar reconstruction obtained by isocentric C-arm (three-dimensional fluoroscopy). The poor image quality caused by metal artifacts allowed no evaluation of screw position. b A postoperative CT scan demonstrated a critical lateral pedicle wall perforation of the right screw in C4 with encroachment of the vertebral foramen (left side of the image)