Lumbar spine instrumentation

We are offering new hope for patients suffering from mechanical back and/or leg pain secondary to spinal cord or nerve root compression through lumbar spinal instrumentation, or LSI. Patients most commonly present with a combination of spinal stenosis and spondylolisthesis causing neural compression. Spinal stenosis is most often seen in patients over 50 and is secondary to degenerative changes that occur in the spine as a result of aging. Spondylolisthesis most often occurs as a result of degenerative changes, but can likewise be seen secondary to trauma to the lumbar spine, or in those patients who are post-laminectomy. The levels most commonly involved are L4-5 and/or LS-SL. Risk factors for these changes to the spinal column include prior spinal or abdominal surgery, obesity, prior trauma or repetitive injury, and cigarette smoking.

Patients with degenerative spondylolisthesis typically present with a long and slowly progressive history of low-back and diffuse bilateral leg pain that increases with ambulation. Patients will commonly say that the distance they are able to walk has become shorter and shorter If the condition is left untreated, it may simply become too painful for the patient to walk, and they may then resort to the use of a wheelchair or other assistive device.

Patients are considered for surgery when efforts at conservative treatment have failed to relieve symptoms. Conservative measures typically include physical therapy, strengthening and conditioning exercises, back bracing, weight loss or other lifestyle changes. This group of patients, who exhibit radiographic evidence of spondylolisthesis, are those most likely to benefit from LSI. Functional outcome following LSI is generally better and more rapid if the patient is diagnosed early, and surgical intervention is accomplished prior to muscle atrophy and an inability to ambulate secondary to neural compression. LSI is intended to decompress the area of stenosis as well as to prevent any progression in the degree of spondylolisthesis. Generous foraminotoimies are performed in order to decompress the neural foramina. Only rarely is it necessary to realign the spine or reduce the slippage in non-traumatic spondylolisthesis.

LSI was once thought to be too traumatic for the older patient. Concerns with cardiac disease, pre-existing medical conditions or blood pressure instability in a patient undergoing a lengthy and complex operative procedure often precluded consideration of surgery in the older patient. Our neurosurgeons can perform this surgery in less than two hours and with minimal blood loss. Fusion rates have been shown to be excellent with the use of pedicle screws for stabilization until natural bony fusion can occur. Patients now ambulate the same day as surgery, so the incidence of complications associated with immobility is greatly reduced.

As a result of decreased operative time, early post-op ambulation and adequate pain control, the length of hospital stay for patients undergoing lumbar spinal instrumentation has decreased by 50 percent since 1994. This reduction in hospital stay, combined with the low incidence of postoperative complications, has resulted in a 40 percent decrease in hospital costs.

Terms

Spondylolisthesis
Spondylolysis is a prerequisite for spondylolisthesis. Spondylolisthesis occurs when spondylolysis weakens one of the vertebrae so much that the bone slips out of place.
The condition can also be caused by degenerative disc disease. If the vertebrae slip too much and begin to press on nerves, surgery may become necessary. Spondylolisthesis may also be caused by degenerative conditions that affect the vertebral joints, such as cerebral palsy.

Early treatment usually involves rest and medication. Progressive spondylolisthesis usually requires surgical treatment.

There are five types of Spondylolisthesis - here are the three most common.

1. Type I is called dysplastic spondylolisthesis and is secondary to a congenital defect of either the superior sacral or inferior L5 facets or both with gradual slipping of the L5 vertebra.

2. Type II, isthmic or spondylolytic, in which the lesion is in the isthmus or pars interarticularis, has the greatest clinical importance in persons under the age of 50. If a defect in the pars interarticularis can be identified but no slipping has occurred, the condition is termed spondylolysis. If one vertebra has slipped forward on the other (horizontal translation), it is referred to as spondylolisthesis.

3. Type III, is a degenerative spondylolisthesis, and occurs as a result of the degeneration of the lumbar facet joints. The alteration in these joints can allow forward or backward vertebral displacement. This type of spondylolisthesis is most often seen in older patients. In Type III, degenerative spondylolisthesis there is no pars defect and the vertebral slippage is never greater than 30%

Outcome Study

The last 80 patients who were treated with LSI for non-traumatic spondylolisthesis were an average age of 60. All these patients underwent surgical fusion using TSRH pedicle screw fixation with rods and crosslinks. Nearly all of the patients likewise had a laminectomy and foraminotomy at the time of surgery. The average length of hospital stay was 4.5 days, with 90 percent of the patients then returning to their homes. Post-op complications were rare, with no fusion failures and only six patients requiring transfusion. Seven patients suffered postoperative infection, three of which were superficial. Fifty-five of these patients had significant preoperative weakness and of those, 91 percent were found to have improved strength at their one-month post-op visit.

Preoperative imaging should include a lumbar myelogram with post-myelogram CT scan. The sagittal CT images will show loss of enhanced spinal fluid in the areas of profound compression as well as any resultant nerve root compression. This serves to indicate which level or levels require decompression. The myelogram with upright views will also determine the degree of slippage of the vertebral bodies and the degree of correction that is necessary to decompress the nerve root.

Overall, LSI generally is a safe and effective operation that is feasible for nearly all patients diagnosed with symptomatic spondylolisthesis who are refractory to conservative management. We are committed to treating patients with the most severe and challenging spinal disorders. Our outcomes data demonstrates that even the elderly patient can achieve a safe and functionally improved outcome.

The Operation

The Incision
The patient is positioned on the operating table in a prone position. The incision is made over the anatomic position of the spinous process.
 

Bone is Removed
When indicated, soft tissue and bony decompression are performed to relieve neurological compression.

Screw Placement
For a degenerative spondylolisthesis case, a blunt probe is inserted through the pedicle and into the vertebral body.

Once the pedicle canals are prepared and the screw length determined, the pedicle screws are sequentially inserted.

                 


Bone Graft
The facet joint capsules are removed and cancellous bone graft is placed into each facet joint. The transverse processes, and the lateral walls of the facet joints are decorticated with high-speed burs and curettes.

Corticocancellous bone graft taken from the bone bank, along with any fragments of bone taken during decompression are firmly pressed into the bone fusion bed.

Call, toll-free, at 888-234-4357 to learn more.

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© 2008 Tri-State Neurosurgical Associates - UPMC

Last Updated: January 1, 2008