Clinical Outcomes of Posterolateral Fusion Versus
Posterior Lumbar Interbody Fusion in Patients
with Lumbar Spinal Stenosis and Degenerative
Instability
Authors: Farrokhi Majid Reza 
Published: October 2019

Background: Degenerative lumbar spine disease can lead to lumbar spine instability. Lumbar spine instability
is defined as an abnormal response to applied loads characterized kinematically by abnormal movement in the
motion segment beyond normal constraints. Patients with lumbar spinal stenosis (LSS) typically present with
low back pain (LBP), cramping, cauda equine syndrome, and signs of nerve root compression associated by
weakness, numbness and tingling in their legs that are worsened with standing and walking. This degenerative
condition severely restricts function, walking ability, and quality of life (QOL).
Objectives: This study aims to compare clinical and radiological outcomes of posterolateral fusion (PLF)
with posterior lumbar interbody fusion (PLIF) with posterior instrumentation in the treatment of LSS and
degenerative instability.
Study Design: A randomized, prospective, controlled clinical study.
Methods: In this prospective study, 88 patients with LSS and degenerative instability were randomly allocated
to one of 2 groups: PLF (Group I) or PLIF (Group II). Primary outcomes were the control of LBP and radicular
pain, evaluated with visual analog scale (VAS), the improvement of QOL assessed by the Oswestry disability
index (ODI) scale, and measurement of fusion rate, Cobb angle, spinal sagittal balance, and modic changes
in the 2 groups.
Results: At 24 months postoperatively, the mean reduction in VAS scores in Group I was more than in Group
II (5.67 vs. 5.48, respectively) and the patients in Group I had more improvement in the ODI score than the
patients in Group II (42.75 vs. 40.94, respectively). There was a statistically significant difference between the
preoperative and postoperative sagittal balance in the 2 groups. The mean Cobb angle changed significantly
in the 2 groups.
Limitations: There are few prospective studies of PLIF or PLF in patients with LSS and degenerative lumbar
spine instability, and a limited number of studies which exists have examined the safety and outcome of each
procedure without comparing it with other fusion techniques. Because most of the studies in the literature
have been conducted in the patients with IS, we could not compare and contrast our findings with studies
in patients with LSS and degenerative lumbar spine instability. In addition, although in our study the findings
at a 24-month follow-up period showed that PLF was better than PLIF in these patients, there were some
studies in which the authors reported that PLIF showed better clinical results than PLF at a 48-month followup period. So we suggest that rigorous controlled trials at longer follow-up periods should be undertaken in
groups of patients with LSS and degenerative lumbar spine instability who undergo posterior decompression
and instrumented fusion to help to determine the ultimate best fusion technique for these patients.
Conclusion: PLF with posterior instrumentation provides better clinical outcomes and improvement in the
LBP, radicular pain, and functional QOL, more correction of the Cobb angle, more restoration of sagittal
alignment, more decrease in Modic type 1, and more increase in Modic type 0, despite the low fusion rate
compared to PLIF.
Key words: Lumbar spinal stenosis, degenerative instability, posterolateral fusion, posterior lumbar interbody
fusion, low back pain, quality of life, cobb angle, fusion rate, mobic changes, sagittal balance