The goal of surgery for degenerative spine disease is to decompress nerves; however, extensive spinal decompression may compromise spinal stability. Therefore, spinal fusion surgery is performed to immediately stabilize such anatomical disruption during a short hospital stay and to allow quick recuperation. Recently, implants such as pedicle screws and intervertebral cages have been regularly used in lumbar fusion surgery. These implants are used to reconstruct the functional unit of the failed spine, correcting any deformity if necessary and maintaining its fixation until complete bone fusion. In other words, the essence of spinal fusion surgery is not the placement of implants but the induction of bone fusion. Therefore, each case requires a carefully developed surgical plan to achieve sufficient bone fusion for spinal stabilization. In this article, we describe the mechanism and the surgical technique for achieving reliable interbody fusion.