Lumbar Spinal Fusion plus Laminectomy is Superior to Laminectomy alone for Grade I Degenerative Spondylolisthesis: SLIP Study Results

Keywords: randomized trial, spondylolisthesis, spinal fusion, laminectomy, pain

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       The value of fusion after laminectomy in patients with spondylolisthesis varies.
     To compare quality of life outcome following laminectomy with fusion to laminectomy alone for lumbar spinal stenosis with grade I spondylolisthesis.
     A prospective, 5-center RCT was conducted from 2002-2009. Patients aged 50-80 with degenerative spondylolisthesis (3-14 mm) with symptomatic lumbar spinal stenosis were eligible. Patients with mechanical instability or gross motion (< 3mm) were excluded.
      Patients were randomized to receive either laminectomy alone or laminectomy with posterolateral instrumented fusion. Primary outcome measure (SF-36 PCS) was assessed in the clinic at 1, 3, 6, and 12 months, and then annually for 5 years by phone. Sample size estimate to demonstrate superiority with 80% power was 64 patients.
     130 patients were screened, 106 were enrolled, and 66 randomized to receive either decompression alone versus decompression with fusion. Mean age was 66.7 years (80.3% female). Follow-up rate was 86% (2 years) and 85% (4 years). Surgery was associated with significant improvement in SF-36 PCS and ODI scores at each time point (P<0.05). Laminectomy with fusion had significantly better SF-36 PCS (primary outcome measure) scores than laminectomy alone at 6 months (P=0.03), 2 years (P=0.02), and at 4 years (P=0.01) post-operatively. For patients treated without fusion, re-operation rate was 12/34 (35.3%). When fusion was added to laminectomy, re-operation rate was considerably lower: 4/31 (12.9%) (P=0.036).
     This was a prospective study. Quality of life was evaluated via SF-36.
     Lumbar spinal fusion added to laminectomy when treating degenerative grade I spondylolisthesis is associated with superior SF-36 PCS outcome.
       Fusion led to fewer re-operations within 4 years of the initial procedure.


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