Study Design: A clinical prospective randomized controlled trial involved 75 patients suffering from isthmic and degenerative lumbar spondylolithesis diagnosed at the outpatient clinic of Department of Neurosurgery, Assuit University Hospital, Egypt.

Background:Posterior lumbar interbody fusion (PLIF) and posterolateral fusion (PLF) are widely used methods for treatment of lumbar spondylolithesis. Some studies showed that PLIF results in an improved outcome compared with PLF, while other studies prove the opposite.

Objective: The purpose of this study was to compare the methods of PLIF and PLF in cases of lumbar spondylolisthesis, and to evaluate the clinical efficacy of the procedures.

Methods: 60 patients with lumbar spondylolisthesis were operated between 2017 and 2019. Indications for surgery were low-back pain with or without sciatica and neurogenic claudication that had not improved after at least 6 months of conservative treatment. The study included 38 female and 22 male patients, with mean ages of  49.3±8 years in the PLIF group and 50.43±8 years in the PLF group. These patients were randomly allocated into 2 groups 30 patients each. The 2 groups had similar socioeconomic, age and sex distribution, level of pain, and disability. Inclusion criteria and outcome measurements were identical in both groups. In the PLIF group, Polyetheretherketone (PEEK) cages were used, and  autograft material was obtained from laminectomy was used in both groups. A minimum 12 month follow-up was available in all patients. For clinical evaluation, a visual analog scale, and Oswestry Disability Index were used. Improvements in pre- and postoperative spondylolisthesis, segmental angles, occurrence of fusion, and postoperative complications were evaluated radiologically.

Results: The patients were followed up at 3, 6, and 12 months postoperatively. Based on the etiologies, isthmic spondylolisthesis was detected in 25patients and degenerative spondylolithesis was detected in 35 patients. In PLIF patients, Oswestry disability index (ODI) improved from 29.8% to 13.2% and the visual analogue scale (VAS) for back pain from 7.5 to 1.3. The levels of ODI and VAS were similar to that of the PLF group. Fusion ratios were 100% in the PLIF group and 90% in the PLF group. There was no difference in the complication rates for each group.

Conclusions: There is no significant difference in the one year outcome of surgical treatment of adult isthmic and degenerative spondylolisthesis. we advise PLIF when discectomy is needed and PLF when there is no need for discectomy.  

Key Words: lumbar spondylolisthesis, isthmic spondylolisthesis, posterolateral fusion, posterior lumbar interbody fusion and intertransverse process fusion.