Utility of modified transarticular screw in the middle and lower cervical spine as intermediate fixation in posterior long fusion surgery.

OBJECT

The use of a pedicle screw (PS) in the cervical spine ensures strong fixation. However, 6.7-29% of such screws appear to be malpositioned using manual insertion techniques, especially at C-3 to C-6 where the pedicle diameter is smaller, potentially causing catastrophic complications such as vertebral artery (VA) and spinal cord or nerve root injuries. To optimize safety, the authors use a new technique: cephalad and/or caudad ends at C-2 and C-7/T-1, respectively, are fixed with PSs, and intermediate points around C3-6 are fixed using a modified transarticular screw technique that captures 3 dorsal cortices and preserves the ventral cortex of the facet in posterior long fusion surgery involving occipitospinal fixation. The purpose of the present study was to demonstrate this technique and evaluate the clinical and radiological outcomes.

METHODS

Thirty-nine patients, 8 men and 31 women, with a mean age of 61.7 +/- 11.0 years at surgery, were included in the study. Twenty-eight occipitospinal fusions and 11 posterior long fusions were performed. Patients were divided into 2 groups: a rheumatoid arthritis (RA) group consisting of 26 patients and a non-RA group of 13 patients including 7 with athetoid cerebral palsy. Clinical outcomes were evaluated according to the Japanese Orthopaedic Association (JOA) score. For radiological evaluation, the Cobb angle on lateral radiographs was measured preoperatively, postoperatively, and at the final follow-up, and the degree of realignment from pre- to postoperation and the loss of correction from postoperation to the follow-up were compared between the 2 patient groups.

RESULTS

The recovery rate of the JOA score was 50.6 +/- 20.7% in the RA group and 37.3 +/- 24.3% in the non-RA group. Neither VA injury nor spinal cord or nerve root injury occurred among this series. The degree of realignment was greater in the non-RA group (9.2 +/- 13.9 degrees ) than the RA group (1.4 +/- 12.7 degrees ) as the Cobb angle was more kyphotic preoperatively in the non-RA group (2.9 +/- 18.6 degrees ) than in the RA group (17.4 +/- 15.7 degrees ). However, 38.5% of patients in the non-RA group had a correction loss > 10% compared with 7.7% in the RA group; this difference was statistically significant.

CONCLUSIONS

The featured transarticular screw technique, which preserves the ventral cortex of the facet, as intermediate fixation in long fusion is a safe and easy procedure with few complications. It ensures acceptable clinical and radiological outcomes, especially in patients with RA.