The indirect decompression effect of oblique lateral interbody fusion in the treatment of degenerative lumbar stenosis

Objective To investigate the indirect decompression effect of oblique lateral interbody fusion (OLIF) in the treatment of mild to moderate degenerative lumbar stenosis. Methods From October 2014 to November 2016, 23 patients with mild to moderate lumbar spinal stenosis underwent OLIF combined with or without posterior pedicle screw fixation; 9 males and 14 females with average age of 59.2±11.6 years old; 8 cases at L3, 4 segment and 15 cases at L4, 5 segment. All cases were followed up for more than 6 months. Thin layer scanning of CT and two-dimensional reconstruction images were used to measure the vertical diameter and area of intervertebral foramen. Intervertebral disc height and spinal canal anteroposterior diameter were measured on median sagittal MRI sequence, and the anteroposterior diameter and the cross-sectional area of the spinal canal were measured on cross-sectional MRI sequence. The clinical effects were assessed by the visual analogue score (VAS) and the Oswestry disability index (ODI) for low back pain, lower limb pain and lower limb numbness. Results Compared with those measurements pre-operatively, the post-operative intervertebral disc height increased by 78.6%±13.4%. The post-operative left vertical diameter of intervertebral foramen increased by 36.7%±7.8%, and the post-operative left area of intervertebral foramen increased by 36.6%±8.7%, and the post-operative right vertical diameter of intervertebral foramen increased by 40.7%±9.6%, and the post-operative right area of intervertebral foramen increased by 40.0%±8.9%. The post-operative anteroposterior diameter of sagittal spinal canal were increased 32.6%±5.9%, and the post-operative anteroposterior diameter of cross-sectional spinal canal were increased 34.4%±6.8%, and the post-operative cross-sectional area of the spinal canal were increased 47.5%±7.2%. All of the differences were statistically significant between pre-operative and post-operative measurements. The VAS score for low back pain was 6.2±1.7 pre-operatively, and 1.1±0.5 post-operatively. The ODI for low back pain was 81.2%±18.2% pre-operatively, and 6.1%±2.0% post-operatively. The VAS score for lower limb pain was 5.6±1.4 pre-operatively, and 0.8±0.3 post-operatively. And the VAS score for lower limb numbness was 6.6±2.0 pre-operatively, and 3.4±1.2 post-operatively. All of the differences were statistically significant between pre-operative and post-operative evaluations. Conclusion There were obvious radiological evidences and remarkable clinical effect of indirect decompression using OLIF technique in treatment of mild to moderate lumbar spinal stenosis at early post-operative stage. However further long-term follow-up studies with multicenter large sample were still needed. Key words: Lumbar vertebrae; Spinal stenosis; Spinal fusion