Abstract: Objective　To study the effect of secondary decompression on nerve roots after surgical treatment for severe isthmic spondylolisthesis.　Methods　Clinical and imaging data of 36 patients with severe spondylolisthesis were studied retrospectively. All patients were treated with posterior lumbar intebody fusion(PLIF). Implanted pedicle screws and laminectomy decompression were performed  for the nerve roots after reduction of spondylolisthesis again. The surgical duration and intraoperative blood loss of all patients were recorded. The VAS score, Oswestry dysfunction index (ODI), Japanese Orthopaedic Association (JOA) score, spondylolisthesis angle and spondylolisthesis rate of all patients were analyzed before surgery, 3 months and 2 years after surgery to evaluate the clinical efficacy.     Results    Surgical duration was（96±22）min, and volume of blood loss was（152±68）ml. There was significant difference between 3 months after surgery and the preoperative period on VAS score, ODI index, JOA score, spondylolisthesis angle and spondylolisthesis rate (P<0.05). There was no significant difference between 2 years after operation and 3 months after surgery on VAS score, ODI index, JOA score, spondylolisthesis angle and spondylolisthesis rate(P>0.05).　Conclusion　Secondary decompression on nerve roots for severe spondylolisthesis can relieve nerve compression and get good clinical effect.

Key words: Spondylolisthesis, 　Nerve roots secondary decompression,  ,  , Interbody fusion,  , Internal fixation