Abstract: Objective To analyze the characteristics of redundant nerve roots (RNRs) in patients with lumbar spinal stenosis (LSS) by magnetic resonance (MRI), to observe the clinical outcome of posterior lumbar interbody fusion (PLIF) and to explore the clinical value of RNRs in the choice of operation and prognosis. Methods A total of 209 patients with LSS who were confirmed clinically and treated with PLIF were collected. The patients were divided into groups according to whether there were RNRs in the sagittal T2-weighted images of lumbar. The cross-sectional area (CSA) of the narrowest part of lumbar spine was measured. Lumbar Oswestry Disability Index (ODI) score and Visual Analogue Scale (VAS) score were made for patients before and after operation. Results There were 85 cases in the RNRs group and 124 cases in the nonRNRs group, and the incidence of RNRs was 40.7%. Compared with the control group, the age, the degree of spinal stenosis, ODI score and VAS score were higher in RNRs group (P＜0.01). There was no significant difference in sex ratio between the two groups (P＞0.05). After PLIF treatment, 68 patients were relieved RNRs in the RNRs group (relief group), and 17 patients were not relieved RNRs (unrelieved group), with an unrelieved rate of 20.0%. The postoperative ODI score and VAS score were significantly higher in the unrelieved group than those in the relief group and the control group (P＜0.05), but there were no significant differences in the clinical scores between the relief group and the control group (P＞0.05). Conclusion The key to evaluate the surgical outcomes of LSS is whether the postoperative RNRs are relieved. There is a relatively poor effect in patients who still have RNRs after surgery than that of patients with RNRs has been relieved after operation. RNRs can be used as the index of surgical prognosis.

Key words: spinal stenosis, magnetic resonance imaging, posterior lumbar interbody fusion, redundant nerve roots