Pedicle Screw Combined With Lateral Mass Screw Fixation in the Treatment of Basilar Invagination and Congenital C2-C3 Fusion.

STUDY DESIGN: Clinical evaluation of a surgical fixation technique featuring combined use of pedicle screw and lateral mass screw (LMS).

OBJECTIVE: Introduction of a novel technique for the treatment of congenital C2-C3 fusion and basilar invagination (BI).

SUMMARY OF BACKGROUND: Posterior occipitocervical fixation using C2 pedicle screw was widely used for BI. However, in cases where BI is concurrent with congenital C2-C3 fusion, the C2 pedicles tend to be thinner than that in normal population and hence more likely to fail. We prompted to tackle the issue by combining the pedicle screw with the additional use of LMS in attempt to strengthen the fixation.

METHODS: Twenty-five patients who underwent combined pedicle screw with LMS fixation were retrospectively studied. The instrument position, fusion status, and complications were analyzed.

RESULTS: None had spinal cord or vertebral artery injury. The average follow-up time was 20 months. Solid fusion was achieved in 23 patients (92%) as detected radiologically. Two cases suffered from recurred BI and instrument failure but eventually achieved solid fusion between the occiput and C2 was after revision. Among all 25 patients, 4 suffered from complications including instruments failure, cerebrospinal fluid leakage, and intracranial infection.

CONCLUSIONS: The clinical outcome indicates that the technique is reliable for the treatment of BI with congenital C2-C3 fusion.