A lumbar fusion is an operation to stabilize the lower back by creating bony bridges between at least two vertebrae and eliminating motion between them. This can be accomplished by fusing the vertebral bodies in front (anterior fusion) or by fusing the facet joints and lamina in the back (posterior fusion). Bone or bone substitutes can be placed on and between the lamina and the facet joints. Metal screws and rods, or plates, may be attached to the bones to secure the fixation while the bony bridge heals.
During the operation, a four-to-five-inch incision is made in the lower back and the muscles supporting the spine are divided. A small window is made in the sheet of bone (lamina) covering the spinal cord. Next, the surgeon removes any ruptured disc material or bone spurs that are pinching the nerves or spinal cord. The site is then prepared for fusion by obtaining a bone graft and/or bone substitute and laying it on the bone. Metal screws and rods or plates may be attached to the bones to secure fixation while the bone heals. The operation typically takes two to three hours; however, it may be longer, depending on the complexity of the problem and the number of vertebrae needing to be fused.