Posterior transpedicular instrumentation with short segmental fixation represents a current trend in surgery for unstable spinal problems, such as spondylolisthesis. A reduction-fixation spinal system with 5.75- to 6.25-mm diameter pedicle screws of variable angles and an 8-mm diameter rod can achieve a rather rigid, short-segment fixation and satisfactory reduction of spondylolisthetic deformities. In clinical applications, 84% of 85 patients with spinal instability had good-to-excellent results for back pain, 88% for sciatica, and 86% for claudication; 91% achieved solid posterolateral fusion from the roentgenographic studies. This reduction-fixation system achieved a reduction of 71% +/- 5.3% of slipping width in this population. Posterior lumbar interbody fusion is mandatory for effective and lasting reduction. Complications from reduction fixation including pedicle-screw loosening (12%), pedicle screw breakage (7%), adjacent instability (7%), and nerve root injury (2%).