Spinal fusion is a "welding" process by which two or more of the small bones (vertebrae) that make up the spinal column are fused together with bone grafts and internal devices such as metal rods to heal into a single solid bone. The surgery eliminates motion between vertebrae segments, which may be desirable when motion is the cause of significant pain. It also stops the progress of a spinal deformity such as scoliosis. A spinal fusion takes away some of the patient's spinal flexibility. Most spinal fusions involve relatively small spinal segments and thus do not limit motion very much. Spinal fusion is used to treat:
- Injuries to spinal vertebrae.
- Protrusion and degeneration of the cushioning disk between vertebrae (sometimes called slipped disk or herniated disk).
- Abnormal curvatures (such as scoliosis or kyphosis).
- Weak or unstable spine caused by infections or tumors.
More than 325,000 spinal fusions were performed in 2003. About 137,000 procedures involved the upper (cervical) spine. About 162,000 involved the lower (lumbar) spine. (Source: National Center for Health Statistics, Centers for Disease Control and Prevention; 2003 National Hospital Discharge Survey).
Bone is the most commonly used material to help promote fusion. Generally, small pieces of bone are placed into the space between the vertebrae to be fused. Sometimes larger solid pieces of bone are used to provide immediate structural support. Bone may come from:
- The patient (autogenous bone).
- A bank of bone harvested from other individuals (allograft bone).
Autogenous bone is generally considered superior at promoting fusion. But drawbacks to using it include extra surgery to remove bone from the patient's body such as the hip or pelvis. Allograft bone is available from bone banks. Other bone graft substitutes are being developed, but have yet to be proven as cost effective substitutes for autogenous bone graft for general use.
After the fusion procedure has been performed, the adjacent spinal segments are held immobile to allow fusion to progress. Immobilization is achieved through internal fixation devices or external bracing or casting. Both forms of immobilization may be necessary at times.
Risks for any surgery include bleeding and infection. Additional risks for spinal fusion surgery include urinary difficulties (retention) and temporary decreased or absent intestinal function. Patients can best prepare for spinal fusion surgery by:
- Thoroughly consulting with their doctor before surgery.
- Banking their blood.
- Achieving good nutritional status before and after surgery.
- Following a recommended exercise program before and after surgery.
- Maintaining a positive mental attitude.
- Stopping smoking.
There is usually pain for the first few days after surgery. Pain medication will be given regularly, perhaps by a patient-controlled analgesia (PCA). The patient will probably have a urinary catheter.
The fused spine must be kept in proper alignment. The patient will be taught how to move properly, reposition, sit, stand and walk. While in bed, the patient will be instructed to turn frequently using a "log rolling" technique in which the entire body is moved as a unit, not twisting the spine. The patient may be discharged from the hospital with a back brace or cast. The family will be taught how to provide care at home.
American Academy of Orthopaedic Surgeons. "Spinal Fusion". July 2001. < http://orthoinfo.aaos.org/fact/thr_report.cfm?Thread_ID=156&topcategory=Spine >.
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