Spinal fusion treats a variety of pathological conditions to eliminate abnormal motion of the vertebrae that causes pain, neurological deficit, or spinal deformity. Common conditions incorporating spinal fusion in their surgical treatment are spinal stenosis,spondylolisthesis, cervical discopathy, spinal fractures, scoliosis, and kyphosis.
Spinal fusion is done most commonly in the lumbar region of the spine, but it is also used to treat cervical and thoracic problems. The indications for lumbar spinal fusion are controversial. People rarely have problems with the thoracic spine because there is little normal motion in the thoracic spine. Spinal fusion in the thoracic region is most often associated with spinal deformities, such asscoliosis and kyphosis.
Cervical spinal fusion can be performed for several reasons. Following injury, this surgery can help stabilize the neck and prevent damage to the spinal cord. Additionally, cervical spinal fusion can be used to remove or reduce pressure on nerve roots caused by bone ingrowth osteophytes or herniated intervertebral disks.
Patients who require spinal fusion have either neurological deficits or severe pain that hasn't responded to conservative treatment. Spinal fusion surgeries are also common in patients who suffer from moderate to severe back deformities that require reconstructive surgery.
When performing spinal fusion, the surgeon usually performs two procedures:
Conditions where spinal fusion may be considered include the following:
There are two main types of lumbar spinal fusion, which may be used in conjunction with each other:
1.Posterolateral fusion places the bone graft between the transverse processes in the back of the spine. These vertebrae are then fixed in place with screws and/or wire through the pedicles of each vertebra attaching to a metal rod on each side of the vertebrae.
In most cases, the fusion is augmented by a process called fixation, involving the placement of metallic screws (pedicle screws often made from titanium), rods, plates, or cages to stabilize the vertebrae and facilitate bone fusion. The fusion process typically takes 6 to 12 months after surgery. During this time external bracing (orthotics) may be required. External factors such as smoking, osteoporosis, certain medications, and heavy activity can prolong or even prevent the fusion process. If fusion does not occur, patients may require reoperation.
Some newly introduced technologies avoid fusion and preserve spinal motion. Such procedures, such as artificial disc replacement, are alternatives to fusion in the cervical spine. Their advantage over fusion, however, is not well established. Minimally invasive techniques have also been introduced to reduce complications and recovery time for lumbar spinal fusion.
In spinal fusion, the accuracy of screw insertion into the pedicles directly affects surgical outcome. Accurate placement generally involves considerable judgmental skills developed through lengthy training. Because the impact of misaligning one or more pedicle screws can directly affect patient safety, a number of navigational and trajectory verification approaches have been described and evaluated in the literature to provide some degree of guidance to surgeons.
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