Comparable increases in dural sac area after three different posterior decompression techniques for lumbar spinal stenosis: radiological results from a randomized controlled trial in the NORDSTEN study

Erland Hermansen,Frode Rekeland,Tore Solberg,Tor Åge Myklebust,Jørn Aaen,Ivar Magne Austevoll,Oliver Grundnes,Masoud Anvar,Jens Ivar Brox,Kjersti Storheim,Eric Franssen,Clemens Weber,Knut Jørgen Haug,Helena Brisby,Kari Indrekvam,Hasan Banitalebi,Christian Hellum

doi:10.1007/s00586-020-06499-0

Abstract

PurposeTo investigate changes in dural sac area after three different posterior decompression techniques in patients undergoing surgery for lumbar spinal stenosis.Summary of background dataDecompression of the nerve roots is the main surgical treatment for lumbar spinal stenosis. The aim of this study was to radiologically investigate three commonly used posterior decompression techniques.MethodsThe present study reports data from one of two multicenter randomized trials included in the NORDSTEN study. In the present trial, involving 437 patients undergoing surgery, we report radiological results after three different midline retaining posterior decompression techniques: unilateral laminotomy with crossover (UL) (n = 146), bilateral laminotomy (BL) (n = 142) and spinous process osteotomy (SPO) (n = 149). MRI was performed before and three months after surgery. The increase in dural sac area and Schizas grade at the most stenotic level was evaluated. Three different predefined surgical indicators of substantial decompression were used: (1) postoperative dural sac area of > 100 mm2, (2) increase in the dural sac area of at least 50% and (3) postoperative Schizas grade A or B.ResultsNo differences between the three surgical groups were found in the mean increase in dural sac area. Mean values were 66.0 (SD 41.5) mm2 in the UL-group, 71.9 (SD 37.1) mm2 in the BL-group and 68.1 (SD 41.0) mm2 in the SPO-group (p = 0.49). No differences in the three predefined surgical outcomes between the three groups were found.ConclusionFor patients with lumbar spinal stenosis, the three different surgical techniques provided the same increase in dural sac area.Clinical trial registrationThe study is registered at ClinicalTrials.gov reference on November 22th 2013 under the identifier NCT02007083.

Highlights

Lumbar spinal stenosis (LSS) is a clinical and radiological entity with symptoms predominantly in the lower extremities, including reduced walking capability, neurogenic claudication and sometimes radicular pain
The aim of the present study was to quantify and compare the increase in dural sac area and Schizas grade achieved by three different posterior decompression techniques: unilateral laminotomy with crossover (UL), bilateral laminotomy (BL) and spinous process osteotomy and decompression (SPO)
The main objective of the SST has been published in the study protocol [8], but the present study focuses on the radiological results after the three posterior decompression techniques: UL, BL and SPO

Summary

Introduction

Lumbar spinal stenosis (LSS) is a clinical and radiological entity with symptoms predominantly in the lower extremities, including reduced walking capability, neurogenic claudication and sometimes radicular pain. The goal of surgery is to decompress the nervous and vascular tissue in the spinal canal, and decompressive surgery is the most frequently performed surgical procedure in the adult lumbar spine [2]. A meta-analysis after laminectomy showed success rates as low as 64% [3] and alternative midline retaining techniques have been introduced to improve. Mid-line retaining decompression techniques such as unilateral laminotomy with crossover (UL), bilateral laminotomy (BL) and spinous process osteotomy and decompression (SPO) have become commonly used surgical methods [2]. There is no consensus or scientific evidence [4,5,6] suggesting that any one of these techniques yields superior clinical results compared to the others

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