Cervical pedicle screw fixation in 100 cases of unstable cervical injuries: pedicle axis views obtained using fluoroscopy

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Object

The authors conducted a study to introduce the imaging technique in which pedicle axis views are obtained using fluoroscopy to match the screw entry point with pedicle orientation and to report the clinical results and safety of cervical pedicle screw fixation (PSF) in patients treated for unstable cervical injuries.

Methods

One hundred consecutive patients with unstable cervical injuries underwent PSF in which the authors used fluoroscopic imaging to acquire pedicle axis views. There were 87 men and 13 women whose mean age was 42.5 years. The accuracy of PS placement was examined postoperatively using axial computed tomography (CT) and oblique radiography. Screw malpositioning was classified either as screw exposure (< 50% of the screw outside the pedicle) or pedicle perforation (> 50% of the screw outside the pedicle boundaries).

The mean operative time was 97.6 minutes, and the mean estimated blood loss was 221 ml. Local vertebral alignment around the injured segment measured 6.0° of kyphosis preoperatively and 6.7° of lordosis postoperatively. Solid posterior bone fusion was achieved in all but three patients who died shortly after surgery. There was no secondary dislodgment of instrumentation in 95% of these 97 cases. Of the 419 cervical PSs, 43 (10.3%) were of the screw-exposure type and 17 (4.0%) of the pedicle-perforation type. There were two surgery-related complications: one penetration of a probe into the vertebral artery and one radiculopathy. There were six postoperative complications: two cases of instrumentation failure associated with loss of correction, three cases of correction loss (> 10°), and one case of deep wound infection.

Conclusions

Solid posterior fusion without secondary dislodgment of hardware was demonstrated in 95% of the cases. The incidence of complications associated with cervical PSF was not high. Postoperative CT scanning showed that 17 (4.0%) of 419 screws perforated the pedicle. It appears that fluoroscopy performed using pedicle axis views improves the accuracy and safety of cervical PS insertion.

Abbreviations used in this paper:CT = computed tomography; PS = pedicle screw; PSF = PS fixation; VA = vertebral artery.

Article Information

Address reprint requests to: Yasutsugu Yukawa, M.D., Department of Orthopedic Surgery, Chubu Rosai Hospital, 1-10-6 Komei, Minato-ku, Nagoya, Aichi 455-0018, Japan. email: yukawa.ort@chubuh.rofuku.go.jp.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Axial CT scan of C-5 demonstrating the small diameter of pedicles and the obliquity of the pedicle axis.

  • View in gallery

    Photograph of the intraoperative setup, in which fluoroscopy is used to acquire the pedicle axis view.

  • View in gallery

    Oblique posteroanterior radiograph showing the cortical circle of right-sided pedicles. At the C-6 level, the cortical ring is seen just below the upper endplate, and this is where the real pedicle axis view is obtained (arrow). At the other levels, the pedicle axis and the fluoroscopic axis are out of synchronization, and fine tuning of the fluoroscope is needed to acquire a real pedicle axis view.

  • View in gallery

    Axial CT assessment of screw malposition, revealing screw exposure (arrow in A) and pedicle perforation (arrow in B).

  • View in gallery

    Imaging studies obtained in the illustrative case. A and B: Preoperative posteroanterior (A) and lateral (B) radiographs demonstrating a right unilateral C5–6 facet dislocation (arrow in B). C: The PS entry point is marked by the tip of a cautery knife on the C-5 right lateral mass, using the pedicle axis view created by fluoroscopy. D: The guidewires are inserted into the C-5 and C-6 pedicle holes, and the accuracy of the created trajectory is confirmed on the pedicle axis fluoroscopic images. The arrows indicate the guidewires within the cortical rings of the right C-5 and C-6 pedicles. E and F: Postoperative posteroanterior (E) and lateral (F) radiographs showing good alignment and osseous fusion. G and H: Postoperative axial CT scans revealing good placement of the PSs at C-5 (G) and C-6 (H).

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