Objectives:To investigate the clinical efficacy and outcome of lateral lumbar interbody fusion in the treatment of lumbar spinal stenosis(LSS)with redundant nerve roots(RNRs).Methods:The data of 48 LSS patients with RNRs(23 males and 25 females,aged 45-81 years,on average 65.4±7.5 years)treated with lat-eral lumbar interbody fusion between January 2018 and July 2022 in our hospital were analyzed retrospec-tively.Among the patients,17 cases received single-level surgery and 31 cases received multi-level surgery.On the basis of the postoperative supine MRI scans,the patients were divided into RNRs relieved group(group A)and RNRs unrelieved group(group B).Radiographic assessments included disc heights,segmental angle and cross-sectional area of the spinal canal at the RNRs segment before and after operation were per-formed.The visual analogue scale(VAS),Oswestry disability index(ODI)and Japanese Orthopaedic Association(JOA)score were used to evaluate the clinical outcomes at preoperation and 1 month after surgery.Results:All patients underwent surgery successfully.The preoperative cross-sectional area of the spinal canal was 65.2±21.5mm2 in group A and 35.9±11.5mm2 in group B,with a significant difference(P＜0.05).The posterior disk height and cross-sectional area of the spinal canal was 8.3±1.7mm and 92.6±25.8mm2 respectively in group A,and that of group B was 6.0±2.3mm and 45.4±12.1mm2 respectively,the differences were significant-ly statistical(P＜0.05).Furthermore,in 1 month after operation the VAS leg pain,ODI and JOA scores was 2.4±0.8,(24.1±3.0)%and 22.8±1.9 respectively in group A,and that of group B was 3.3±0.8,(30.2±4.4)%and 17.7±2.5 respectively,the differences were significantly statistical(P＜0.05).The total incidence of complications was 10.4%,including anterolateral thigh pain in 4 cases and hip flexor weakness in 1 case,which were released at 3 months of follow-up.Conclusions:Lateral lumbar interbody fusion can eliminate RNRs by restoring postoperative posterior disc height and enlarging the cross-sectional area of spinal canal,which provides an effective treatment for most LSS patients with RNRs.