During a spinal fusion, a bone graft is used to join two or more vertebrae. The vertebrae grow together during the healing process, creating a solid piece of bone. The bone graft helps the vertebrae heal together, or fuse. The bone graft is usually taken from the pelvis at the time of surgery. However, some surgeons prefer to use bone graft from a bone bank (called allograft).
The posterior approach is done from the back of the patient. This approach can be just a fusion of the vertebral bones or it can include removal of the problem disc. If the disc is removed, it is replaced with a bone graft. The surgeon moves the spinal nerves to one side and inserts the bone graft between the vertebral bodies. This is called a posterior lumbar interbody fusion.
With a posterior approach, an incision is made in the middle of the lower back over the area of the spine that is going to be fused. The muscles are moved to the side so that the surgeon can see the back surface of the vertebrae. Once the spine is visible, the lamina of the vertebra is removed to take pressure off the dura and nerve roots. This allows the surgeon to see areas of pressure on the nerve roots caused by bone spurs, a bulging disc, or thickening of the ligaments. The surgeon can remove or trim these structures to relieve the pressure on the nerves. Once the surgeon is satisfied that all pressure has been removed from the nerves, a fusion is performed. When operating from the backside of the spine, the most common method of performing a spinal fusion is to place strips of bone graft over the back surface of the vertebrae.
A minimum of three months is needed for the bones to fuse together and become solid. Yet the bone graft will continue to mature for one to two years. Your doctor may have you wear a rigid brace for up to three months to keep your spine still and make sure the bones fuse. You may not require a rigid brace after fusion with instrumentation.
Most patients are able to return home when their medical condition is stabilized, usually within one week after fusion surgery. Limit your activities to avoid doing too much too soon. Avoid bending, lifting, twisting, and driving for at least six weeks.