Spinal fusion is a surgical procedure that treats instabilities in the spine that cause pain and deformity. The procedure involves joining two or more vertebrae and fusing them into a single bone. Fusion reduces pain by stopping the motion at the segment of the spine that is causing the pain, allowing the patient to enjoy everyday activities. The key to success is getting the bone to heal together. Hardware is a tool to reduce deformity and eliminate the need for a brace, but if the bone does not heal the hardware will eventually crush or break.
Spinal fusion treats low back pain cause by disc degeneration, such as degenerative disc disease, herniated disc, or spondylolisthesis. It is also used to treat back problems brought on by a fracture or other traumatic injury to the spine.
Fusion surgery can also be used to correct the progression of an abnormal spinal curvature, such as kyphosis or scoliosis. Most procedures to correct scoliotic curves feature spinal fusion as a major component.
During a spinal fusion, the surgeon places a bone graft–generally taken from the patient’s pelvic bone or rib, but sometimes from a bone bank–between two or more vertebrae. Recently the use of BMP (Bone Morphogenic Protein) has reduced the need for bone graft. Over a period of about four to nine months following surgery, your body will produce living bone to replace the bone graft. This new bone will fuse the vertebrae together and they will grow into a single bone. During this period, spinal segments must be held immobile to allow the fusion to complete itself. This immobilization requires the use of either internal instrumentation (plates, wires, rods, hooks, or screws) or external tools (braces or casts). Depending on the type and location of the problem, your surgeon can perform spinal fusion from the front (anterior fusion), from the back (posterior fusion), or from both sides.
The surgeon will make an incision in the chest or side and remove inter-vertebral discs in the area of the curve to make the spine more flexible. After placing screws in the vertebrae, the surgeon will connect them using a metal rod. The surgeon will then replace the removed discs with bone graft so that the vertebrae on either side of the graft will fuse together. By tightening down the screws attached to the metal rod, the surgeon will straighten the curve.
In performing this procedure, the surgeon will approach the spine through the back. The surgeon will attach anchors to the spine in the form of hooks, screws, or wires. These anchors are then attached to spinal rods that straighten the spine. As in anterior instrumentation, bone grafting fuses all instrumented vertebrae.
This surgery actually consists of two separate operations–one through the front and the other through the back. Your surgeon may choose to stage the two operations on separate days or perform them together as part of one longer surgery. Compared to a single surgical procedure, staged procedures require one to two additional days in the hospital.
Since spinal fusion joins two or more vertebrae together, many patients raise concerns about a loss of flexibility. Any loss of flexibility depends on the number of vertebrae fused together and their location. Most fusions involve a small number of vertebrae, so the loss of flexibility is minimal. In addition, the reduction of pain often offsets this minor loss of flexibility by allowing most patients to feel even more active. However, even in spinal fusion if pain relief is achieved, patients readily accept the stiffness.