Long-term Results of Computer-assisted Posterior Occipitocervical Reconstruction

Abstract

Instability of the occipitocervical junction can present challenging surgical problems because of the unique anatomic and biomechanical characteristics of this region. The purpose of this study was to evaluate the long-term surgical results and usefulness of a computed tomography (CT)-based navigation system for the occipitocervical reconstruction. Twenty-three patients (10 men, 13 women; mean age at surgery 57.9 years; mean follow-up periods 52.9 months) with occipitocervical junction disorders were treated by occipitocervical reconstruction using pedicle screws, aided by a CT-based navigation system. Roentgenologic measurement and clinical evaluation were performed before surgery and at final follow-up. Postoperative CT and plane radiographs were used to determine the accuracy of screw placement. Mean atlantodental interval and Ranawat value were significantly improved (P<.05), and mean clivoaxial angle was increased after surgery and maintained at final follow-up. Mean Japanese Orthopedic Association score before and at final follow-up was 7.1 ± 4.4 and 11.3 ± 3.5 points, showing significant improvement (P = .005). Fourteen patients (61%) improved more than one Ranawat grade. Six of nine patients (67%) in class IIIB were improved. On the other hand, nine patients (39 %) remained at the same class at final follow-up. A total of 88 pedicle screws were inserted into cervical and upper thoracic pedicles using the navigation system, and only one screw (1.1 %) showed major pedicle wall perforation. Solid union was achieved in all 23 patients. Occipitocervical reconstruction using pedicle screws provided a high fusion rate and maintained alignment in the occipitocervical region. The computer-assisted navigation system was a useful tool for accurate and safe pedicle screw insertion.