Extracted from Augusta Orthopedic Surgery

Another type of spine surgery is spinal fusion. The diseased disc and lamina are first removed. Pieces of bone are removed from your hip (donor) and are placed along the spine and between the vertebrae. This is called bone grafting. When the bone heals, this is called a bone fusion and the vertebrae no longer move separately. This fusion takes three months to heal.

Indications for Spinal Fusion

When a disc ruptures, the hydraulic effect of the disc is disrupted.  The facet joints (the joints between two vertebrae), muscles, and surrounding ligaments are required to take over the job of the disc.  If the disc does not heal, it is said to be degenerative. A degenerative disc is not able to support the weight of the body and the space between vertebra narrows. When the space between two vertebra narrows, so do the holes (or foramen) that the nerves pass through. This causes the nerve to be pinched and results in leg and/or back pain. Over time the facet joints become arthritic, get larger, and develop bone spurs.

This is called spondylolisis and narrows the formen even further. Finally, as the facet joints become arthritic and lose their cartilage, they begin to slide on one another. This allows one vertebrae to “slip” on the other, narrowing the hole even more. This kind of slipping and narrowing is a dynamic process and is worse when sitting or riding in a car and is called spondylolisthesis.

When a nerve is pinched by a ruptured disc, the disc material can be removed to relieve pressure on the nerve (laminectomy and discectomy). When the disc is degenerative and the nerve is pinched by bone (from narrowing of the disc space and foramen, spondylolisis, and slipping or spondlylolisthesis), spinal fusion is indicated to relieve pressure on the nerve and keep the vertebra from slipping.

With the development of fusion cages, it is now much easier to relieve pressure on a pinched nerve, keep the vertebra from slipping, and getting the fusion to heal. The fusion cages can be put in from the back or from the front. We prefer to put our cages in from the back because, the nerves can be seen better and protected better during surgery and the holes (foramen) can be made bigger allowing the nerve more room.