European Journal of Cardiovascular Medicine

Lumbosacral spondylolisthesis stands as the most prevalent spinal disorder, with an estimated 4-6% of the general population being impacted by this condition ¹.   Spondylolysis, the main cause of lumbosacral spondylolisthesis, is identified in approximately 6% of the general population. Within this demographic, it is expected that approximately one-third will undergo the progression of spondylolisthesis to varying degrees ².

The displacement of the upper vertebra over the lower one results in alterations in the morphology of the neural foramen, leading to the entrapment of the nerve root in a compressed and narrowed neural foramen. Clinical manifestations vary, encompassing mild to severe symptoms of lower back pain, with or without accompanying radiculopathy most commonly at L5/S1 and L4/5 ^{3 4}. The primary objective of surgical techniques is to achieve decompression and stabilization of the affected vertebrae. A frequently employed procedure involves a posterior instrumented interbody fusion performed at a single level ^{5 6}. Widely accepted fusion techniques include Posterolateral fusion (PLF), posterior lumbar interbody fusion (PLIF), and transforaminal lumbar interbody fusion (TLIF) ⁷.

Despite the evolution of various management approaches over many years, there is currently a lack of high-level evidence regarding the optimal surgical strategy ⁸. The TLIF technique for treating spondylolisthesis was developed by Harms and Jeszensky ⁹. Preceding TLIF, PLIF has limitations, confined to the L3 to S1 levels due to the potential risk of neurological structure damage from excessive retraction on the thecal sac at higher levels ¹⁰. Moreover, TLIF, with its unilateral approach, eliminates the need for contralateral facet joint and lamina involvement, preserving an additional surface for fusion ¹¹.

Our study aims to offer specific regional data by analyzing a consecutive series of selected patients who underwent any posterior decompression and spinal fusion surgery. The primary focus is on evaluating the surgical outcomes and documenting any complications. Additionally, functional outcomes were assessed.

This is a prospective observational study. Once we obtained approval from the institutional ethics commitee, we created a consecutive cohort of patients who had intended to undergo surgical intervention for a low-grade degenrative spondylolisthesis at tertiary care Hospital, Ongole, Andhra Pradesh. The study was conducted from December 2022 to June 2023 and follow up was done from June 2023 to February 2024. Based on the inclusion criteria for selection, the study consisted of 40 consecutive patients.   Patients who were taking long-term medications such as opioids and sedatives, those who exhibited facet tenderness unrelated to the spondylolisthesis level, individuals who had undergone previous spinal surgery, and patients with diabetic neuropathy and vascular claudication were excluded from the study. 

Patient information such as demographics, presenting symptoms, and the affected spinal level were recorded.   A comprehensive radiological assessment of spinopelvic parameters was conducted using standard plain radiographs, dynamic radiographs, and MRI imaging.   Analysis of surgical data included evaluating operative time, blood loss, technique and intraoperative complications. The outcome was to assess post-operative normalization measured in terms of VAS scores, Oswestry Disability Index (ODI) and Radiological assessment.

The mean age was 52.37 years, with a range of 41 to 72 years.   A total of 11 men and 29 women were involved in the study.   The average duration of symptoms was 11.09 months, ranging from 8 to 24 months. All patients experienced low-back pain, neurological claudication, and/or radiating pain in the lower extremities. The most common radiographic finding was decreased disc space (72.5%) followed by loss of lumbar lordosis (17.5%) [Table no.1].

Table 1: Radiographic findings

            Surface-level wound infection was seen in 11 patients, but it was effectively treated with oral antibiotics.   During follow up period, 2 patients had screw breakage, 1 patient had screw bending and 1 patient had screw loosening. The following table includes details of postoperative complications [Table no.2]. 

Table 2: Post-operative complications

The mean follow-up period lasted 8.5 months, ranging from 7 to 8 months.The neurological and functional recovery of patients, as indicated by the VAS score and ODI, demonstrated a statistically significant improvement at all times throughout the follow up period. [Table no.3]

Table 3: Functional outcomes (paired t-test)

Pre-operative pelvic incidence was 58.1 ± 12.9 and post-operatively it is almost similar with 58.5 ± 12.5 (p>0.05; not significant). Pelvic tilt also has similar lesser difference with 19.6 ± 6.7 pre-operatively and 19.8 ± 5.2 post-operatively (p>0.05; not significant). Sacral slope also has no difference with 35.1 ± 8.5 pre-operatively and 35.8 ± 7.5 post-operatively (p>0.05; not significant). The change in lumbar lordosis is significant with -40.1 ± 17.8 pre-operatively and -49.3 ± 18.5 post-operatively (p<0.05; significant). Segmental lumbar lordosis also has a significant difference pre and post-operatively with -5.7 ± 1.1 and -10.7 ± 6.5 respectively (p<0.05; significant). [Table no.4]

Table 4: Radiological parameters

  Of the 40 patients, 31 (77.5%) were able to achieve grade-I fusion, while 5 (12.5%) achieved grade-II fusion.   4 patients experienced pseudoarthroses (grade III or IV). Analyzing the radiological fusion in conjunction with clinical scores, it was found that lower grades of radiological fusion were associated with higher VAS scores for pain (P < 0.01). In grade-I fusions, the average VAS score was 2.3 and the average ODI was 21.1, while in grade-II fusions, the average VAS score was 1.66 and the average ODI was 18.7.  [Table no.5]

Table 5: Fusion grade and functional result

Table 6: Correlation between fusion rate and clinical improvement

  After a successful fusion procedure, over 70% of patients experienced a decrease in pain of more than 50%, while 63.5% saw a reduction in ODI of more than 30%. [Table no.6] 

Various surgical treatment options are accessible for managing adult isthmic low grade spondylolisthesis (grade 1 and 2). Certain authors advocate for the use of circumferential fusion alone along with decompression, while others propose circumferential fusion combined with reduction of listhesis.   The literature presents conflicting perspectives on the surgical approach, but overall results indicate positive clinical outcomes ranging from good to excellent ^3,4,12,13. The most common radiographic finding was decreased disc space (72.5%) followed by loss of lumbar lordosis (17.5%) in the present study. Similar results were reported in a study done  by Kakadiya DG et al ¹⁴.  Throughout the duration of the follow-up period, three patients experienced screw breakage, three patients had screw bending, and two patients had screw loosening.   In addition, other research studies have documented a similarly low occurrence of complications ^{11, 15}. 

Statistically significant improvements were observed in pain scores (VAS and ODI) and significant improvement in SLR test at 3 months and 6 months follow-up after surgery compared to before the operation.   The improvement remained significant when comparing results at 3 months with those at 12 months. Hackenberg et al ¹⁶ discovered consistent results with the current study, showing the average preoperative ODI score was 41.6% and decreased to 31.6% at the most recent follow-up.   Butterman et al ¹⁷ also observed improvement in ODI score, with a mean change from 63% to 33% three years post fusion surgery for Spondylolisthesis.

In the present study fusion was evaluated using radiographic criteria and we have achieved an 82% fusion rate.   Various studies have reported fusion rates ranging from 68% to 100% with posterolateral fusion in low-grade spondylolisthesis. Schnee CL et al ¹⁸  highlighted in their research that there is contradictory information in the literature about the connection between fusion and clinical results in treating lumbar spinal issues.   They noted in their study that despite a 90% fusion rate being achieved; only 60% of patients reported positive clinical outcomes.  McGuire R.A et al ¹⁹ conducted a prospective study which found a direct relationship between failure to achieve arthrodesis and unsatisfactory pain outcome.   El Masry et al ⁶ also reported a similar direct relationship between failure to achieve a satisfactory arthrodesis and an unsatisfactory outcome. 

In this study, we discovered that inadequate radiological fusion was associated with unfavorable clinical and functional outcomes.   When examining radiological fusion alongside clinical scores, lower grades of radiological fusion were linked to higher VAS scores for pain (p < 0.01). Specifically, for grade-I and grade-II fusions, the average VAS scores were 2.3 and 1.6, and the average ODI scores were 21.1 and 18.7 twelve months after surgery.   This is in contrast to the average VAS score of 6.1 and average ODI score of 38.3 in grade-IV fusion (non-union). Kakadiya DG et al ¹⁴ also reported similar findings in their study where the average ODI scores were 19.09 and 17.66 in grade-I and grade-II fusions  and the average VAS score of 6.0 and average ODI score of 36 in grade-IV fusion. Debnath UK et al ²⁰ reported in their study that all patients in the fusion group experienced a significant improvement in VAS (back pain) compared to those in the non-fusion group (p=0.03). However there was no significant statistical association between successful fusion and clinical outcomes, such as VAS (back/leg pain) or ODI scores.

Surgical interventions for symptomatic low- and mid-grade spondylolisthesis have shown better functional clinical results and improved pain management. Choosing posterior decompression and spinal fusion can lead to successful fusion with minimal complications. A greater pelvic incidence may play a critical role in the progression of developmental spondylolisthesis. 

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