Spinal fusion is a surgical procedure used to correct problems with the small bones in the spine (vertebrae). It is essentially a "welding" process. The basic idea is to fuse together the painful vertebrae so that they heal into a single, solid bone.

This article focuses on just the surgical component of posterolateral lumbar fusion. For a complete overview of spinal fusion, including approaches, bone grafting, complications, and rehabilitation, please go to Spinal FusionSpinal Fusion (topic.cfm?topic=A00348).

In a posterior approach to lumbar fusion, the surgeon makes an incision down the middle of the lower back. To see the vertebrae, the surgeon will pull back the muscles that surround the spine. In many cases, the surgeon will remove arthritic bone and other structures that may be putting pressure on spinal nerves. This is called a decompression, or laminectomy.

A posterior approach to lumbar surgery. An incision is made over the vertebrae that will be fused.

(Left) Muscles surrounding the spine are pulled back to expose the bone. (Right) After a decompression, bone graft material and screws are placed along the sides of the vertebrae.

After the decompression, the surgeon will place graft material along the sides of the vertebrae to stimulate bone growth. This is called a posterolateral fusion. Titanium screws and rods are often used to provide immediate stability to the spine until a solid fusion has been achieved. These screws typically are not removed even after the bone graft has healed.

Back and side views of posterolateral fusion with screws.