Improved postoperative course after spinous process segmental instrumentation of thoracolumbar fractures. This article compares the postoperative course of 40 patients who had Harrington instrumentation with 40 patients who had Harrington instrumentation and interspinous process segmental instrumentation of unstable thoracolumbar fractures and reviews the findings. The two groups of patients were otherwise homogeneous, and average operative time, total blood loss, and days to oral intake were similar for both groups of patients. On average, however, patients undergoing interspinous process segmental instrumentation were out of bed sooner (4.5 versus 7.7 days, P less than 0.0001), discharged sooner (32 versus 38 days, P less than 0.079), and brace-free earlier (2.1 versus 5.9 months, P less than 0.001) and had fewer fixation-related complications than did patients undergoing Harrington instrumentation alone. Comparison of average hospital costs documented a savings of $5,160 for the typical patient undergoing interspinous process segmental instrumentation. 