A single-level lumbar interbody fusion is a surgical procedure used to stabilize one segment of the lower back by permanently joining two adjacent vertebrae. It is typically recommended when pain, nerve symptoms, or instability caused by conditions such as degenerative disc disease, spinal stenosis, disc herniation, or spondylolisthesis have not improved with conservative treatments. The goal of the surgery is to stop painful motion at the affected level, relieve pressure on spinal nerves, and restore proper disc height and spinal alignment. Before surgery, patients undergo imaging and clinical evaluation to confirm that symptoms originate from a single lumbar level. Once surgery is planned, the specific surgical approach is chosen based on anatomy, diagnosis, and surgeon preference. Common approaches include accessing the spine from the back, side, or front of the body, each designed to safely reach the disc space while minimizing disruption to surrounding structures. During the procedure, the damaged disc between the two vertebrae is removed. A spacer or cage filled with bone graft material is then placed into the empty disc space to restore height and support proper alignment. Screws and rods are typically added to stabilize the spine while the bone graft promotes fusion, allowing the two vertebrae to gradually grow together into one solid unit. Although the surgical route may vary, the core steps of disc removal, spacer placement, stabilization, and fusion remain the same for a single-level procedure. After surgery, patients are usually encouraged to begin walking early, often the same day, to support circulation and recovery. Hospital stays vary, but many patients are able to return home within a short period. Recovery continues over weeks to months as fusion progresses. Light activities and daily tasks are gradually resumed, with return to work and driving often possible within a few weeks, depending on the individual and the nature of their job. Full recovery and fusion take longer, but many patients experience significant improvement in pain, function, and overall quality of life.