The result of S1 double screw fixation in patients not suited for L4 and/or L5 pedicle screw insertion

Abstract

Variable methods are available for sacropelvic fixation. The usefulness of S1 double screw fixation for deformity surgery is established, but its effectiveness in cases where the L4 and/or L5 pedicle screw is not appropriate has not been reported. We reviewed medical records to identify long-segment, lumbar spine fixation involving S1 double screws. Nine such patients were treated between November 2006 and November 2012 at our center: all patients had infectious spondylitis involving L4 and/or L5. Two patients were excluded due to a limited follow-up period (< 6 months). The remaining seven patients were enrolled. We used dynamic X-rays or three-dimensional computed tomography (3D-CT) to assess any change in the lumbar alignment angle and to evaluate bony fusion with the graft material. The mean observation period of the seven patients was 16.9 months (range: 6-25). The mean age was 63.43 years (range: 55-73). Four patients were women. The average number of fusion levels was 3.5 ± 1.1. The ideal positioning and maintenance of the S1 double screws and bony fusion with the graft materials were confirmed using serial imaging. Lordosis in the lumbar region was immediately restored after surgery (27.0 ° ± 10.4 to 35.1 ° ± 10.7), and maintained with slight decrease (31.6 ° ± 8.8) throughout the follow-up period. S1 double screws provided stability when L4 and/or L5 pedicle screw fixation was not possible. Our results suggest that S1 double screws are a viable option for sacropelvic fixation in selected patients.