94 adult patients with isthmic spondylolisthesis were randomized to be treated with either conventional in situ posterior lumbar interbody fusion (PLIF) or a draw-back technique, using pedicle screws to reduce vertebral slippage, combined with PLIF. The purpose was to determine the effect of slipped verterbrae reduction on clinical outcomes, radiographic outcomes, and complication rate. Patients were followed up for an average 32.5 months. The results indicated that the draw-back technique significantly reduced slip percentage, increased disk height, and increased lumbar lordosis as compared with in situ fusion, with similar complication rates between groups. However, there was no difference between groups regarding clinical outcome, with both groups improving significantly from baseline.