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Fig. 1 MRI showing Grade 1 degenerative spondylolisthesis with anterior displacement of L4 on L5. Graphic
courtesy of Jonathon D. Lurie, MD

AAOS Now

Published 9/1/2009
|
Annie Hayashi

SPORT supports surgical treatment for spondylolisthesis

Pain relief, functional improvements continue at 4 years

Two years ago, results from the Spine Patients Outcomes Research Trial (SPORT) study showed that surgical treatment of degenerative spondylolisthesis and associated spinal stenosis resulted in greater short-term improvements than nonsurgical treatment. A recent review of the data at the 4-year mark supported that conclusion.

“Over 4 years, patients with spinal stenosis and degenerative spondylolisthesis had better outcomes when treated with surgery rather than with nonsurgical treatment,” said Jonathon D. Lurie, MD, MS. “Those who also had neurogenic claudication received greater relative benefits from surgery than those with radicular symptoms.”

Because other studies had shown that the benefits of surgery diminished with longer term follow-up, the SPORT study investigators decided to reassess the pain and functional outcomes in patients after 4 years.

Investigators face challenges
“We faced a number of challenges—an elderly population with many comorbidities, pragmatic surgical and nonsurgical protocols, and a large number of crossovers,” Dr. Lurie explained.

Using the original randomized and observational cohorts, researchers measured pain and function using Short Form (SF)-36 scores and the AAOS Musculoskeletal Outcomes Data Evaluation and Management System (MODEMS) version of the Oswestry Disability Index. Secondary outcome measures included patient self-reports, the Stenosis Bothersome Index Scale, and the Leg Pain Bothersome Scale.

All patients had degenerative spondylolisthesis with spinal stenosis confirmed by radiographs or imaging (Fig.1), a history of at least 12 weeks of symptoms, neurogenic claudication or radicular leg pain, and confirmation from a physician that they were a surgical candidate.

A decompressive laminectomy was the standard surgical protocol. If warranted, a single level fusion was also performed. According to Dr. Lurie, most patients received fusions as well as posterior instrumentation with pedicle screws.

Patients in the nonsurgical group received physical therapy, epidural steroid injections, nonsteroidal anti-inflammatory drugs, and opioid-based medications.

“The nonsurgical treatment was individualized to the patient. Patients who had tried an intervention prior to enrollment or during the study and were still symptomatic were offered as much reasonable nonsurgical treatment as possible,” said Dr. Lurie.

Crossover affects results
During the course of the study, in both the randomized and observational cohorts, a large number of participants in the nonsurgical treatment group opted to have surgery. The initial analysis of the randomized cohort, which was based on intent-to-treat, was changed to an as-treated analysis. Times were adjusted accordingly—from date of enrollment (intent-to-treat) to date of surgery (as-treated).

To ensure that the randomized and observational groups were comparable, the investigators analyzed the as-treated estimates of the treatment effect of each group. In subsequent analyses, the randomized and observational cohorts were combined for analysis.

“We found similar outcomes whether the patients were in the randomized or observational cohort, with no significant differences between the treatment effects in the as-treated analyses. These findings supported the validity of the combined analysis,” said Dr. Lurie.

The treatment effect was defined as “the difference in the mean changes, as compared with baseline, between the surgical and nonsurgical treatment groups.”

Surgery found more effective
Of the 607 patients enrolled in the study, 395 patients had surgery within 4 years; 345 of these patients (87 percent) had surgery during the first year. About one third of patients (212 patients) elected nonsurgical treatment (
Table 1).

“In the combined analysis, the treatment effects were significantly in favor of surgery for all primary and secondary outcome measures at each time point out to 4 years,” said Dr. Lurie.

Surgery was more effective in resolving neurogenic claudication than nonsurgical treatment. Approximately 85 percent of the patients had neurogenic claudication, while 15 percent had radicular symptoms with evidence of nerve root irritation. Patients with radicular symptoms had surgical outcomes similar to those of patients with neurogenic claudication. They did experience greater improvement on average with nonsurgical intervention, however. As a result, patients with radicular symptoms had a smaller relative benefit from surgery than patients with neurogenic claudication.

“Surgical compared with nonoperative treatment for lumbar degenerative spondylolisthesis. Four-year results in the Spine Patient Outcomes Research Trial (SPORT) randomized and observational cohorts” appeared in the June 2009 issue of The Journal of Bone and Joint Surgery—American.

Dr. Lurie’s co-authors include James J. Weinstein, DO, MS; Tor D. Tosteson, ScD; Wenyan Zhao, Emily A. Blood, MS; Anna N.A. Tosteson, ScD; Nancy Birkmeyer, PhD; Harry N. Herkowitz, MD; Michael C. Longley, MD; Lawrence G. Lenke, MD; Sanford E. Emery, MD, MBA, and Serena S. Hu, MD.

The authors report the following disclosures: Dr. Herkowitz— Medtronic, Stryker; Dr. Lenke— DePuy, A Johnson & Johnson Company; Medtronic, Axial Biotech; Dr. Emery— DePuy, A Johnson & Johnson Company; Medtronic Sofamor Danek; Dr. Hu— Synthes; DePuy, A Johnson & Johnson Company; Medtronic Sofamor Danek.

Dr. Weinstein reported no conflicts. No disclosure information was available for the other authors.

Annie Hayashi is the senior science writer for AAOS Now. She can be reached at hayashi@aaos.org