Spinal fusion is surgery to permanently join together two or more vertebrae in the spine so there is no movement between them. Spinal fusion may be done by itself or along with surgery to remove bone and tissue that are narrowing the spinal canal and squeezing the spinal cord and/or the spinal nerves.
There are many potential reasons for a surgeon to consider fusing the vertebrae. These include: treatment of a fractured (broken) vertebra; correction of deformity (spinal curves or slippages); elimination of pain from painful motion; treatment of instability; and treatment of some cervical disc herniations. Another condition that is treated by fusion surgery is actual or potential instability. Instability refers to abnormal or excessive motion between two or more vertebrae. It is commonly believed that instability can either be a source of back or neck pain or cause potential irritation or damage to adjacent nerves. Although there is some disagreement on the precise definition of instability, many surgeons agree that definite instability of one or more segments of the spine is an indication for fusion.
There are many surgical approaches and methods available to fuse the spine, and they all involve placement of a bone graft between the vertebrae. The spine may be approached and the graft placed either from the back (posterior approach), from the front (anterior approach) or by a combination of both. In the neck, the anterior approach is more common; lumbar and thoracic fusion is more commonly performed posteriorly. The ultimate goal of fusion is to obtain a solid union between two or more vertebrae. Fusion may or may not involve use of supplemental hardware (instrumentation) such as plates, screws and cages. Instrumentation is sometimes used to correct a deformity, but usually is used as an internal splint to hold the vertebrae together while the bone grafts heal.
The immediate discomfort following spinal fusion is generally greater than with other types of spinal surgeries. Fortunately, there are excellent methods of postoperative pain control available, including oral pain medications and intravenous injections. Another option is a patient-controlled postoperative pain control pump. With this technique, the patient presses a button that delivers a predetermined amount of narcotic pain medication through an intravenous line. This device is frequently used for the first few days following surgery. Recovery following fusion surgery is generally longer than for other types of spinal surgery. Patients generally stay in the hospital for three or four days, but a longer stay after more extensive surgery is not uncommon. A short stay in a rehabilitation unit after release from the hospital is often recommended for patients who had extensive surgery, or for elderly or debilitated patients.