Degenerative Lumbar Spinal Stenosis (LSS) is an extremely common condition affecting more than 102 million people each year. It is a narrowing of the spinal canal in the lower back. It causes pain and even disorders of the lower limbs. When the symptoms get worse and the individual feels functional discomfort despite medical treatment, surgical intervention is recommended. Two surgical options are available: Rigid Stabilization Devices as conventional fusion with or without cage, or dynamic stabilization system as B-DYN device, this system is called dynamic because it allows the stabilization of the operated part while preserving a certain mobility. The main objective of this study is to evaluate the efficacy and tolerance of B-Dyn versus conventional bolted fusion (with or without cage) in the treatment of degenerative lumbar stenosis (DLS) on the degree of postoperative functional incapacity. So the investigator's hypothesis is that the use of the B-DYN device in the treatment of DLS could lead to the maintenance of functional disability related to low back pain (maintenance of walking and mobility). Another important point to be demonstrated in this study is the preservation of the mobility of the stage overlying the assembly performed by B-Dyn. Indeed, the continued degeneration of segments adjacent to lumbar vertebral fusions is a concern for surgeons For B-Dyn, which is a dynamic stabilization, the combination of rigid and flexible parts allows the mobility of the overlying stage to be preserved and could also lead to a decrease in adjacent syndrome in the long-term compared to the use of conventional fusion. The duration of patient follow-up is 60 months. The inclusion period is 56 months to recruit the necessary number of subjects for the study (a total of 216 patients is expected).