Circumferential minimally invasive approach for low-grade isthmic spondylolisthesis: A clinical and radiological study of 43 patients.

INTRODUCTION: Circumferential fusion for lumbar low-grade isthmic spondylolisthesis (LGIS) provides the best spinal stability and highest fusion rates. The aim of this study is to investigate results of minimal invasive management of LGIS and correlations between Intervertebral Foramen Surface (IFS) and other parameters.

METHODS: We retrospectively reviewed cases of 43 patients who underwent a minimally invasive circumferential fusion (Anterior lumbar interbody fusion followed by percutaneous posterior pedicle screw fixation) for LGIS between January 2010 and December 2014 in our institution. Inclusion criteria were one-level (L4-L5 or L5-S1) LGIS with low back and/or radicular pain. Pre- and postoperative radiographic evaluations were performed at 6, 12 and 24months. Measurements (Percentage of anterior displacement, degree of slip angle, height of the intervertebral space and the IFS) were obtained using Surgimap® .

RESULTS: Nineteen patients (44.2%) were males. Mean age was 43 years old (19-72years). The mean follow-up of the series was 18.3months (3-72months). Mean preoperative Visual Analogy Scale (VAS) for low back pain decreased from 70mm to 20mm and from 80mm to 10mm as to radicular pain. Anterior displacement was reduced from 18% to 7% (p<0.01), degree of slippage were increased from 9.8° to 15.2° (p<0.01), intervertebral height was restored from 4.4mm to 8.5mm (p<0.01) and increase of the IFS was calculated 48.8%.

CONCLUSION: One stage circumferential fixation for adults' LGIS without decompression, allows restoration of intervertebral height permitting good reduction of the slippage, an increasing of the IFS and liberation of nerve roots.