In Patients with Lumbar Spinal Stenosis, Adding Fusion Surgery to Decompression Surgery Did Not Improve Outcomes at 2 Years

Hu, Serena S. MD

Journal of Bone & Joint Surgery - American Volume:
doi: 10.2106/JBJS.16.00885
Evidence-Based Orthopaedics
Author Information

1Department of Orthopedic Surgery, Stanford University, Stanford, California

Article Outline

Försth P, Ólafsson G, Carlsson T, Frost A, Borgström F, Fritzell P, Öhagen P, Michaëlsson K, Sandén B. A randomized, controlled trial of fusion surgery for lumbar spinal stenosis. N Engl J Med. 2016 Apr 14;374(15):1413-23.

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In patients with lumbar spinal stenosis, with or without degenerative spondylolisthesis, does adding fusion surgery to decompression surgery improve clinical outcomes at 2 years?

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Randomized (allocation concealed)*, unblinded, controlled trial with 2 years of follow-up. Swedish Spinal Stenosis Study (SSSS). NCT01994512. (*Information provided by author.)

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7 hospitals in Sweden.

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247 patients 50 to 80 years of age (mean age, 67 years; 67% women) who had lumbar spinal stenosis with ≤2 adjacent stenotic segments, a back pain score of >30 of 100 on a visual analog scale (VAS), pseudoclaudication in 1 or both legs, and symptoms for >6 months. Exclusion criteria were stenosis due to a herniated disc or nondegenerative changes, spondylolysis, degenerative lumbar scoliosis, previous vertebral compression fractures in the same segments, previous lumbar spinal surgery for stenosis or instability, other specified spinal conditions, or psychological disorders of concern to the surgeon. 92% of patients had surgery, completed follow-up at 2 years, and were included in the per-protocol analysis. Outcomes at 5 years were assessed in <80% of patients and are not reported here.

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Decompression surgery plus fusion surgery (n = 123) or decompression surgery alone (n = 124).

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Main outcome measures:

The primary outcome was the Oswestry Disability Index (ODI) score. Secondary outcomes included European Quality of Life-5 Dimensions score, VAS scores for back pain and leg pain, and 6-minute walk distance. 320 patients were needed to detect a 12-point difference between groups on the ODI (80% power, α = 0.05), assuming a 10% drop-out rate and 25% of patients with spondylolisthesis. The sample size was revised to 247 patients during the study because the proportion of patients with spondylolisthesis was greater than expected.

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Main results:

55% of patients had spondylolisthesis at baseline. Patients managed with decompression surgery with versus without fusion did not differ in terms of ODI scores (mean, 27 versus 24 [p = 0.241]; higher scores = more disability) or 6-minute walk distance (mean, 397 versus 405 m [p = 0.72]) at 2 years. Results were similar in patients with or without spondylolisthesis at baseline (Table).

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In patients with lumbar spinal stenosis, adding fusion surgery to decompression surgery did not improve outcomes at 2 years.

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Source of funding:

Uppsala University; Uppsala County Council; S. Stockholm Spine Center.

For correspondence: Dr. Peter Försth, Uppsala University, Uppsala, Sweden. E-mail address:

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Försth and colleagues challenge a common teaching in spine surgery—that spinal fusion can improve outcomes in patients with degenerative spondylolisthesis and spinal stenosis. Although there is no evidence to suggest that spinal fusion benefits patients undergoing surgical decompression for the treatment of spinal stenosis without spondylolisthesis, spinal fusion rates are increasing for patients with stenosis1. It is accepted among many spinal surgeons that decompression should be performed with spinal fusion for optimal outcomes in patients with degenerative spondylolisthesis. This practice is supported by the findings of the Spine Patient Outcomes Research Trial, a randomized trial and observational cohort study that compared surgical with nonsurgical treatment at 13 participating centers2. Almost all patients with degenerative spondylolisthesis had decompression with fusion surgery2.

The trial by Försth and colleagues is well designed. Randomization was stratified according to whether or not patients had spondylolisthesis, a key consideration for many surgeons. Patients who had fusion did not differ from those who did not in terms of any of the assessed patient outcomes, including functional scores and VAS back and leg pain scores. Although the authors did not perform flexion-extension radiographs, a post hoc subgroup analysis in patients with spondylolisthesis and ≥7.4 mm of slippage showed no difference between the treatments at 2 years.

It is worth noting that 1 of the classic studies that favored fusion for patients with degenerative spondylolisthesis3 involved the performance of laminectomies rather than decompression surgery as in the trial by Försth and colleagues. A more limited decompression may not lead to progressive instability, which may explain why patients in the earlier series benefited from fusion.

Given the findings of Försth and colleagues, surgeons and patients should reconsider the indications for fusion in those having decompression for spinal stenosis.

Disclosure: The authors indicated that no external funding was received for any aspect of this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article.

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1. Bae HW, Rajaee SS, Kanim LE. Nationwide trends in the surgical management of lumbar spinal stenosis. Spine (Phila Pa 1976). 2013 ;38(11):916–26.
2. Pearson AM, Lurie JD, Blood EA, Frymoyer JW, Braeutigam H, An H, Girardi FP, Weinstein JN. Spine patient outcomes research trial: radiographic predictors of clinical outcomes after operative or nonoperative treatment of degenerative spondylolisthesis. Spine (Phila Pa 1976). 2008 ;33(25):2759–66.
3. Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg Am. 1991 ;73(6):802–8.
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