Long-segment Fixation with Posterolateral Fusion Versus Short-segment Fixation with Interbody Fusion for Management of High-Grade Lumbar Spondylolisthesis

INTRODUCTION

Complete pars discontinuity is often required to permit such a level of anterior vertebral translation, though it may happen less frequently in other settings. The majority of high-grade spondylolistheses are caused by isthmic and degenerative spondylolistheses. Higher-grade slips may disrupt the patient's overall sagittal balance, altering gait patterns and compensatory posture. ¹

Chronic low back pain patients may experience decreased pain and disability by having their lumbar spondylolisthesis surgically fused, which is a crucial approach to spine stabilization. ²

Many different techniques have been employed to treat spondylolisthesis, including anterior lumbar interbody fusion, posterior lumbar interbody fusion (PLIF), posterolateral fusion (PLF), and circumferential fusion. ³

Both techniques aim to enhance fusion rates and clinical satisfaction. But it's not unclear whether the more complicated technique, when combined, results in superior clinical results. ⁴

Because lumbar spondylolisthesis is frequently associated with additional abnormalities, including forward slide and kyphosis, it frequently leads to a global sagittal imbalance of the spine. When evaluating and treating patients with spondylolisthesis, spinopelvic sagittal balance is critical. Traditionally, fixation has involved inserting pedicle screws into the slipping and lower vertebral bodies, a technique termed "short segment fixation." Long segment fixation was achieved with the insertion of extra pedicle screws into the slipping vertebra's upper vertebrae. ⁵

There have been few studies comparing the lumbar spondylolisthesis sagittal balance of short segment vs. long segment pedicle screw fixation. Considering the importance of sagittal balance in predicting the success of surgery, it is critical to investigate the effects of placing varied numbers of screws on lumbar spondylolisthesis patients' sagittal balance.

This study was conducted to assess the results of long-segment with posterolateral fusion fixation (Long-segment PLF) versus short-segment fixation with interbody fusion (Short-segment PLIF) for the treatment of high-grade lumbar spondylolisthesis.

PATIENTS AND METHODS

PATIENTS:

A total of 60 high-grade lumbar spondylolisthesis patients will be enrolled in the study.

Study design:

Prospective, randomized comparison study.

Setting:

Al Azhar university hospitals.

Target population:

High-grade lumbar spondylolisthesis patients.

Inclusion criteria:

Patients with confirmed high-grade lumbar spondylolisthesis (Meyerding grade III or IV) [6].

Patients with low back pain, intermittent claudication, unilateral/do sciatica symptoms, and who have not improved with conservative treatment for more than six months).

Exclusion criteria:

Patients with intervertebral space infection.

Patients with acute vertebral fractures.

Patients with congenital spinal malformation.

Patients with spinal tumors.

Patients’ randomization:

According to the used surgical technique, we recruited 60 high-grade lumbar spondylolisthesis patients into 2 independent groups:

Long-segment PLF group

(30                patients)

Short-segment PLIF group

(30 patients)

METHODS

Patients have been undergoing the following:

Full history taking.

Full neurological examination.

VAS for back pain.

VAS for leg pain.

Pre-operative radiological assessment (X-rays and MRI).

Pre-operative Japanese Orthopedic Association score (JOA score) [7].

Surgical techniques:

Posterior decompression with insitu posterior transpedicular screw fixation and posterolateral fusion by long segment [long-segment] fixation (Long-segment PLF).

Posterior decompression, reduction, transpedicular screw fixation [short segment] with interbody fusion (Short-segment PLIF).

Post-operative outcome measures:

VAS for back pain.

VAS for leg pain.

Post-operative radiological assessment (X-rays and MRI).

Post-operative JOA score.

Rate of complications.

Patients’ satisfaction outcome.

Ethical Considerations:

 All patients will be included in this study only after giving written consent.

Statistical analysis:

Data entry and statistical analysis have been performed employing MedCalc version 20 (MedCalc, Belgium). We employed significance tests (Mann-Whitney's, Wilcoxon's, Chi-squared tests, factorial ANOVA, and logistic regression analysis).

RESULTS

The average age of the study population was (47.1 ± 11.2) years old, and they weighed an average of (81.9 ± 9) kg. The majority (63.3%) of patients were female, whereas only 36.7% were male, according to the patients' gender (Error! Reference source not found.).

In terms of preoperative data, leg pain had an average VAS value of (7 ± 1.5) while back pain received an average VAS rating of (5.46 ± 2.3) and the average JOA score was (6 ± 0.94), with (10%) of patients having previous surgery (Error! Reference source not found.).

Regarding lumbar disc slips, (40%) of patients had L4-5-disc slips, and (60%) had L5-S1 disc slips, while (85%) had acquired disc slips, and (15%) had developmental disc slips, with Grade-3 slips (78.3%) and Grade-4 slips (21.7%) (Error! Reference source not found.).

Regarding post-operative data, the average VAS rating for back pain was (2.4 ± 1.5), the average VAS rating for leg pain was (1.5 ± 2.3), and the average JOA score was (13.2 ± 2.2), with nobody suffering mortality.

Regarding the complications rate, (28.3%) of patients suffered complications, of which (5%) had Dural tear / CSF leak, (8.3%) had Infection, (3.3%) had Root injury / Foot drop, and (11.7%) had Traction neuropathy / Sciatica.

Regarding outcome (patients’ satisfaction); (8.3%) of patients had a poor outcome, (16.7%) had a fair outcome, (46.7%) had a good outcome, and (28.3%) had an excellent outcome.

Comparative analysis:

Regarding comparative studies, according to the surgical technique used, the 60 high-grade lumbar spondylolisthesis patients have been split into two independent groups: the long-segment PLF group (30 patients) and the short-segment PLIF group (30 patients):

Regarding pre-operative data, a comparison study between the two groups indicated that:

Highly significant increase in L5-S1 disc slips in the long-segment PLF group compared to the short-segment PLIF group (p = 0.0017).

Non-significant difference in the remaining pre-operative data (p > 0.05) (Error! Reference source not found.).

Table 1: Comparison of preoperative data from the two groups employing Mann-Whitney's U and Chi-square tests

Follow up data:

We further compared and analyzed 30 (paired) patients based on pre-and post-surgical serial measurements. The comparison between presurgical and postsurgical measurements showed:

Highly significant decrease in VAS scores (back and leg pain) in the long-segment PLF group (p < 0.01 respectively).

Highly significant increase in JOA score in the long-segment PLF group (p < 0.01).

Highly significant decrease in VAS scores (back and leg pain) in the short-segment PLF group (p < 0.01 respectively).

Highly significant increase in JOA score in the short-segment PLF group (p < 0.01) (Fig. 1, Fig. 2, Fig. 3).

Fig. 1: Comparison of the 2 patient groups regarding serial pre- and post-operative VAS score (back pain) assessments.

Fig. 2: Comparison of the 2 patient groups concerning serial pre- and post-operative VAS score (leg pain) assessments

Fig. 3: Comparison of the 2 patient groups concerning serial pre- and post-operative JOA score assessments

Regarding postsurgical data, a comparison study between the two groups indicated that:

Highly significant decrease in complications rate, in Long-segment PLF group; compared to Short-segment PLIF group (p < 0.05 respectively).

Non-significant difference as regards postsurgical outcome (patients’ satisfaction), VAS scores, and JOA scores (p > 0.05) (Error! Reference source not found., Fig. 4).

Table 2: Comparison of the two groups regarding post-operative data employing Mann-Whitney's U and Chi square tests.

Fig. 4: Comparison of the two groups concerning the rate of complications

Correlation studies:

Studies of correlation between post-operative results and their respective independent predictors (basic clinical, radiological, surgical technique variables) showed the following:

After using the "Forward technique" and adding various predictor factors, a logistic regression analysis reveals that the rise in age, female gender, and short-segment PLF operations all independently increased the likelihood of complications occurring, with significant statistical differences (p < 0.05 respectively) (Error! Reference source not found.).

Other factors excluded from the model as (p value > 0.1). OR: odds ratio.

Table 3: Logistic regression model using the Forward approach for variables influencing the occurrence of complications.

Logistic regression analysis reveals that, after using the (Forward technique) and inserting a few predictor factors, the reduction in age had an independent influence on improving the likelihood of a good satisfaction outcome, with statistically significant differences (p = 0.0031) (Table 4).

Other factors were omitted from the model as (p value > 0.1). OR: odds ratio.

Table 4: Logistic regression model for variables influencing good satisfaction outcome using the Forward approach.

Pre. op MRI                                              Post op. x ray

Fig. 5: Case example (inter-body fusion case L4-5).

Pre. op MRI                                              Post op. x ray

     Fig. 6: Case example (inter-body fusion case L5-S1).

Fig. 7: case example of long segment fixation.