Study compares minimally invasive and open surgeries for lower back pain

Rush University Medical Center is assessing whether minimally invasive surgery to relieve lower back pain differs from open surgery in terms of complication rate, recovery time, outcome and cost.

A total of 50 patients will be enrolled in the study, including those diagnosed with spinal stenosis in the lower back, a narrowing of the spine that causes pressure on the spinal cord, and those with spondylolisthesis, a condition in which a vertebra in the lower part of the spine slips forward and onto the vertebra beneath it.

All of the patients will undergo spinal fusion surgery in which two or more vertebrae are "welded" together to prevent the abnormal movement that is causing pain. Half of the patients will undergo a minimally invasive procedure and half open surgery.

"Minimally invasive back surgery requires new surgical techniques and a steep learning curve," said Dr. Kern Singh, orthopedic spine surgeon and assistant professor at Rush, who is leading the study and does about 200 such surgeries a year.

"Once the learning curve has been passed, the data so far suggest that minimally invasive spinal fusion requires less operating time, reduces the chance of infection and shortens recovery time. All of these are advantageous for the patient."

A traditional open spinal fusion is about a two-and-a-half-hour procedure, involving a five-inch incision in the back to expose the spine, cutting through thick muscles. Typically, bone has to be removed to give the surgeon access to the area where the vertebrae are impinging on the spinal cord. Bone is also removed where it presses on the spinal cord. The vertebrae are fixed in place with screws that attach to a metal rod on either side of the spinal column. Over the six to 12 months after surgery, the bones fuse.

In minimally invasive surgery, which takes a little over an hour, the surgeon requires only a three-quarter-inch incision and maneuvers special instruments in between the muscles, pushing them aside to reach the area of the vertebrae that is pressing on the nerve. No muscles are cut, which reduces postoperative pain. Microscopes enable the physician to view the area in magnification, allowing more surgical precision.

Each patient participating in the study will be followed for two years. Standard postoperative visits at two weeks, six weeks, three months, six months, and one and two years will include MRIs and x-rays of the back, plus clinical tests of range of motion and pain level. In addition at each visit, researchers will analyze the patient's gait, as well as spine strength, with sophisticated computerized tools in Rush's Human Motion Laboratory that allow a detailed assessment of muscle activity patterns all along the spine as the individual walks.

The study will include not only surgical outcomes, but also the costs of the two procedures, an important variable under health care reform.

"By the end, with this tightly controlled study, we hope to have a definitive answer on which type of surgery is more cost-effective and better for the patient." Singh said.