The TLIF procedire can be used with or without a cage depending upon the situation. In 99% of cases, I use a cage. This acts just like a “spacer” to bring the disc space height up to “normal”. This increases the height of the foramen (the nerve exit zone) and returns the correct angulation of the vertebral segments (restores the lordosis).
The cage occasionally cannot be placed if the disc is so degenerative and surrounded by osteophytes that prevent the distraction of the disc space but that condition is rare.
Dr. Corenman