Daniel M. Keller, PhD

April 30, 2012

April 30, 2012 (Miami, Florida) — Lumbar spinal fusion plus laminectomy appears to be a better option than laminectomy alone in terms of quality of life for patients with degenerative grade I spondylolisthesis with lumbar spinal stenosis.

Zoher Ghogawala, MD, director of the Wallace Clinical Trials Center at Greenwich Hospital in Greenwich, Connecticut, presented these results from a prospective, 5-center, randomized, controlled trial here at the 80th Annual Scientific Meeting of the American Association of Neurological Surgeons.

He showed that patients who underwent laminectomy with instrumented fusion reported superior quality-of-life outcomes, as measured by the Short-Form (SF)–36 Physical Component Summary (PCS) instrument at 2 and 4 years and had fewer reoperations within 5 years after the initial procedure compared with patients undergoing laminectomy alone.

Degenerative lumbar spinal stenosis is the most frequent indication for spinal surgery in patients older than 65 years, and 20% of the patients undergo a reoperation within 5 years. Up until now, there had been no data on the utility of fusion vs laminectomy alone. Dr. Ghogawala referred to published data showing that the use of complex spinal fusion increased dramatically in the past decade. With a mean hospital charge for fusion of almost $81,000, vs just under $24,000 for decompression alone, both government and private payers have criticized fusion and put pressure on its use.

The study, called Spinal Laminectomy vs Instrumented Pedicle screw fusion (SLIP), enrolled patients aged 50 to 80 years with symptomatic spinal stenosis and single-level grade I spondylolisthesis of 3 to 14 mm. Patients with gross instability less than 3 mm on flexion/extension, a history of lumbar spinal surgery, or serious medical illness were excluded.

Patients were randomly assigned to lumbar laminectomy alone (n = 35) or to laminectomy with pedicle screw fixation and posterolateral fusion (n = 31). At baseline, the groups were well matched for age (mean, 67 years), sex (77% to 84% women), SF-36 PCS score (31.5 to 34.7), and Oswestry disability index score (ODI; 36.8 to 38.8). More than 90% of patients in each group were available for follow-up at 1 year, and more than 80% were available at 2 years.

The primary outcome measure was a difference of 5 on the SF-36 PCS score at 2 years, for which a higher score is better. Secondary outcomes were a difference of 10 on the ODI (lower score better) and the reoperation rate.

Significant Improvements in Quality of Life

Dr. Ghogawala reported that for the 2 groups together, there was a significant improvement in the SF-36 PCS scores, with a durable improvement over 2 years. From a preoperative combined score for the 2 groups of about 33, the score steadily increased over the first 6 months to about 45, where it remained out to the 2-year point (P < .001). Reduction in disability as measured by the ODI score was also sustained over the trial period.

The primary outcome of the SF-36 score "showed a significant improvement with the addition of fusion in patients treated in this trial, that is, patients treated with an instrumented spinal fusion had better outcomes using SF-36 2 years, 3 years, 4 years, and 5 years after the initial surgery," he said (P = .035). At 5 years, the instrumented group had an SF-36 score of about 46 vs about 42 for the laminectomy-alone group.

"One remarkable and striking difference between the 2 groups was the rate of reoperation," Dr. Ghogawala noted. The investigators found a 10% rate of reoperation in the laminectomy plus fusion patients, whereas 30% of the laminectomy-alone group required reoperation over 5 years (P = .03). The differences in reoperation rates were apparent as early as 1 year and certainly by 2 years.

All of the laminectomy-alone patients who required reoperation had developed instability of the spine at the index level and underwent fusion, "and these operations were successful in improving their outcome" on both the SF-36 and the ODI at 1 year after reoperation (P ≤ .01), Dr. Ghogawala said. "Nevertheless, despite those patients who were treated with fusion [later] in the trial, the overall results of the trial demonstrate that initial, up-front fusion resulted in superior outcomes."

Some limitations of the trial are its small size and its tightly defined population, which may limit generalizability of the findings to patients who present differently. Furthermore, the trial took 7 years to complete, and the technology changed over that time (notably, bone morphogenetic protein and minimally invasive spine surgery were introduced, neither of which was used in the trial).

Cost Issues

Discussant Praveen Mummaneni, MD, associate professor of neurological surgery at the University of California, San Francisco, noted that the cost of laminectomy with fusion is triple the cost of laminectomy alone, and fusion doubles the operative time and increases the hospital length of stay.

He praised the study for the long follow-up period, and he said that following a patient for 6 weeks, as most neurosurgeons do, is not adequate. He predicted that in the future neurosurgeons will have to demonstrate clinical outcome success if they want operations to be paid for. He said the added cost of the fusion "was likely justified by the improved clinical outcomes and the lower reoperation rate for the fusion cohort."

When asked who should be candidates for laminectomy with up-front fusion, Dr. Mummaneni told Medscape Medical News that "I think the current thinking is that if the patients are satisfying criteria for a degenerative spondylolisthesis and they have especially the risk factors of a mobile spondylolisthesis on their X-ray with a tall disc space height, that they're likely better served to have a fusion up front because if they do that they have a two-thirds less chance of having to come back to the operating room for a reoperation within 2 years." He also said he would like to see a cost analysis from this study and whether the costs are adjusted for inflation, which he said are "very important key parameters."

Dr. Ghogawala has disclosed no relevant financial relationships. Dr. Mummaneni has been a consultant for Depuy Spine in the past and receives royalties from that company. He also receives royalties from Quality Medical Publishers.

80th Annual Scientific Meeting of the American Association of Neurological Surgeons: Abstract # 603. Presented April 16, 2012.

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