One hundred sixty-nine patients with symptomatic degenerative or spondylolytic lumbar spondylolisthesis were randomized to receive either percutaneous pedicle screw placement with mini-open midline decompression (n=81) or conventional open decompression with instrumented fusion (n=88). The primary outcome was low back pain at 2 weeks, measured on a visual analogue scale (VAS). Secondary outcomes included leg pain (VAS), Oswestry Disability Index (ODI), EQ-5D quality of life, blood loss, surgical time, hospital stay, and complication rates, assessed at 2 and 6 weeks, 3 and 6 months, and 1 year. Overall, the results revealed no statistically or clinically significant differences between groups in primary or secondary outcomes at any follow-up point, including the hypothesized short-term benefit for back pain. These findings suggest that percutaneous screw placement with mini-open decompression does not provide superior pain or functional outcomes compared to open surgery for this patient population.