Comparative Analysis of Adjacent Levels of Degeneration and Clinical Outcomes Between Conventional Pedicle Screws and Percutaneous Pedicle Screws in Treatment of Degenerative Disease at L3-5; A Preliminary Report

OBJECTIVE This study was conducted to compare radiologic changes and clinical outcomes in adjacent level of percutaneous pedicle screws with those of conventional (open) pedicle screws. METHODS From January 2007 to December 2009, 51 patients underwent L3-5 decompression and spinal fusion. Percutaneous pedicle screws were used in 22 patients, and open pedicle screws were used in the remaining patients. For estimation of instability, we performed measurements of change in the lordotic and adjacent segment angles. A retrospective evaluation of the patients' data and several assessment scales was conducted for determination of clinical outcomes. RESULTS The radiological examinations revealed no significant differences, except the L2-3 sagittal angle change. The upper adjacent level angle change in the open group was larger than that in the percutaneous group. In the percutaneous group, the sagittal angle changed from 9.7±3.0° to 11.25±3.6° during the follow-up periods, and in the open group, the sagittal angle changed from 10.8±4.1° to 13.6±4.5°. Radiological instability was observed in 5 patients (17%) in the open group and in 2 patients (9%) in the percutaneous group. Both groups showed similar clinical outcomes. CONCLUSION We suggest that open screws have a greater tendency to cause degenerative change in the upper segment than percutaneous screws. This may be because percutaneous screw fixation causes minimal injury to supporting structures and preserves adjacent facet joints.