Spinal decompression alone is non-inferior to decompression with instrumented fusion over a period of two years in patients with degenerative lumbar spondylolisthesis, according to new research published in the New England Journal of Medicine (NEJM).
An open-label, multicentre, non-inferiority randomised controlled trial (NORDSTEN-DS)—the findings of which were reported by Ivar M. Austevoll (Haukeland University Hospital, Bergen, Norway) et al—involved patients with symptomatic lumbar stenosis that had not responded to conservative management and who had single-level spondylolisthesis of 3mm or more.
Patients were randomly assigned in a 1:1 ratio to undergo decompression surgery alone or decompression surgery with instrumented fusion.
The primary outcome was a reduction of at least 30% in Oswestry Disability Index (ODI) score during the two years after surgery, with a non-inferiority margin of -15 percentage points. Secondary outcomes included the mean change in the ODI score as well as scores on the Zurich Claudication Questionnaire, leg and back pain, the duration of surgery and length of hospital stay, and reoperation within two years.
The mean age of patients was approximately 66 years. Approximately 75% of the patients had leg pain for more than a year, and more than 80% had back pain for more than a year. More than 20% of the spondylolisthesis were defined as “unstable” (i.e., a dynamic slippage of at least 3 mm, or at least 10 degrees increase of angulation, as assessed by dynamic standing radiographs.)
Findings from the RCT showed a mean change from baseline to two years in ODI score of -20.6 in the decompression alone group compared with -21.3 in the fusion group (mean difference, 0.7; 95% confidence interval [CI], −2.8 to 4.3).
In the modified intention-to-treat analysis, 95 of 133 patients (71.4%) in the decompression-alone group and 94 of 129 patients (72.9%) in the fusion group had a reduction of at least 30% in the ODI score (difference, -1.4 percentage points; 95% CI, -12.2 to 9.4), thus showing non-inferiority in decompression alone. Successful fusion was achieved with certainty in 86 of 100 patients who had imaging available at two years.
However, the reoperation rate was slightly higher in the decompression alone group compared to the fusion group (12.5% versus 9.1%; difference, 3.4; 95% CI; −4.6 to 11.5 percentage points.)
Speaking to Spinal News International, Austevoll said: “This trial supports the evidence that the addition of instrumented fusion to decompression is unnecessary in the surgical treatment of the most frequent forms of degenerative lumbar spondylolisthesis. The longer operation time and length of hospital stay, and the costs of implants, indicate that acceptable clinical results can be obtained at a lower cost without fusion.
“We (the NORDSTEN study group) have planned several follow-up studies; one cost-benefit analysis, one predictor analysis, to investigate if any patients (subgroups of patients) could benefit from a fusion procedure, and finally, long-term follow-ups after five and 10 years.”