Abstract
BackgroundIn instrumented posterolateral fusion reduction of a spondylolisthesis is appealing on theoretical grounds since this may lead to indirect decompression of the entrapped nerve roots. However, there is no consensus in the literature whether a beneficial effect of reduction on outcome can be expected. The objective of the current study was to evaluate whether a correlation between the extent of listhesis reduction and clinical improvement could be established.MethodsFrom two ongoing prospective studies 72 patients with a single-level instrumented posterolateral lumbar fusion for low-grade spondylolisthesis (isthmic/degenerative 51/21) were evaluated. Radiographs and clinical outcome scores were available at baseline, 6 weeks and 1 year after surgery. Changes in neuroforaminal morphology were measured on calibrated radiographs. These changes in radiographic parameters were correlated to clinical outcome (Visual Analogue Score (VAS) leg pain, Oswestry Disability Index (ODI)). Fusion status was assessed on Computed Tomography-scan at one year.ResultsA mean spondylolisthesis of 25 percent was reduced to 15 percent at 6 weeks with some loss of reduction to 17 percent at one year. The VAS and ODI significantly improved at both time intervals after surgery (p < 0.001). No significant correlations could be established between the extent of slip reduction and improvement in VAS or ODI (Pearson’s correlation −0.2 and 0.07 respectively at one year); this also accounted for the other radiographic parameters. A fusion rate of 64 percent was seen on CT-scan.ConclusionsClinical outcome was not related to the obtained radiographic reduction of the slipped vertebra in patients with a lumbar fusion for low grade spondylolisthesis. Loss of reduction or non-union on CT-scans had no effect on the clinical outcome. Reduction of a low-grade spondylolisthesis in spinal fusion is appealing, however, there is no evidence that it positively affects clinical outcome on the short term.Trial registrationISRCTN43648350
Highlights
In instrumented posterolateral fusion reduction of a spondylolisthesis is appealing on theoretical grounds since this may lead to indirect decompression of the entrapped nerve roots
Clinical outcome was not related to the obtained radiographic reduction of the slipped vertebra in patients with a lumbar fusion for low grade spondylolisthesis
Study population Seventy-two patients treated for symptomatic low-grade lumbar spondylolisthesis were included in this study, including 58 patients from the Osteogenic protein-1 (OP-1) versus iliac crest autograft study and 14 from the second prospective follow-up study
Summary
In instrumented posterolateral fusion reduction of a spondylolisthesis is appealing on theoretical grounds since this may lead to indirect decompression of the entrapped nerve roots. Slipping of the cranial vertebra generally leads to a deformation of the neuroforamen morphology with subsequent entrapment of the nerve root in the flattened and narrowed neuroforamen. The majority of patients with low-grade symptomatic spondylolisthesis can initially be treated conservatively, starting with physical therapy, activity modification and medication [1,2,4,5,6,8,9]. Various surgical techniques have been described, all aiming for decompression of the entrapped nerve roots and stabilization of the involved vertebral segment regardless of the chosen technique. Most frequently a single-level instrumented posterolateral fusion is performed [4,9,12,13,14,15,16]
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