Spondylolisthesis constitutes a prevalent spinal disorder defined by the anterior slippage of one vertebral body relative to the subjacent vertebra [1]. Epidemiological data reveal an incidence of 3% to 10% within the general population [2]-[4], with isthmic spondylolisthesis occurring in 4% to 8% of adults and degenerative spondylolisthesis showing a higher prevalence, affecting approximately 19.1% of males and 25.0% of females [2][5]. Degenerative and isthmic variants predominate, with overall incidence rising beyond 18% among adults undergoing imaging, and the condition is more common in females and older age groups, particularly over 60 years [2][5]. Often accompanied by radiculopathy, symptoms substantially impair quality of life and daily functioning [6]-[8].

Severity assessment in clinical practice commonly employs the Meyerding classification, which stratifies slippage from grades I to V based on percentage vertebral displacement, facilitating standardized surgical decision-making and prognostic evaluation [9]. The L5-S1 segment represents the most frequent site, followed by L4-L5, with approximately 75% of cases classified as Meyerding grade I [9].

Conservative management is the first-line approach, with most patients improving through activity modification and physiotherapy aimed at pain relief and spinal stabilization [2]. However, surgical intervention becomes necessary in cases of conservative treatment failure, progressive neurological deficit, or significant instability, with the goal of neural decompression and stable arthrodesis, often with instrumentation [6][10]. Low-grade slips may be managed with motion-preserving or limited fusion techniques, while more severe or unstable cases require instrumented fusion procedures [10].

In surgical management, graft selection plays a pivotal role in achieving solid fusion. Local bone grafts harvested during decompression have shown outcomes comparable to interbody cages in terms of fusion rates and functional recovery, while avoiding donor-site morbidity associated with iliac crest harvesting [7][11]. Autogenous grafts provide osteoconductive, osteoinductive, and osteogenic properties superior to allografts and synthetic substitutes, contributing to reliable fusion [12]. Compared with iliac crest grafts, local autografts derived from laminectomy and facetectomy sites offer similar biological advantages without additional morbidity, making them cost-effective and practical, especially in resource-limited settings [13].

Traditional fusion techniques such as PLIF, TLIF, and PLF are widely used, but local autograft techniques reduce complications associated with cages, including migration, subsidence, and hardware failure, while maintaining comparable or superior fusion outcomes [11][13]. They are particularly effective in single-level, low-grade spondylolisthesis, where they achieve solid arthrodesis comparable to iliac crest grafts without donor-site complications [14][15]. For example, transforaminal lumbar interbody fusion using only local bone graft has demonstrated favorable clinical and radiological outcomes with low complication rates in single-level disease [4].

Despite these advantages, further evaluation of outcomes using local autogenous bone graft in instrumented fusion is warranted to establish its effectiveness in routine clinical practice. Therefore, this study aimed to evaluate the clinical and radiological outcomes of lumbar spondylolisthesis treated with posterior decompression and pedicle screw-rod fixation using local autogenous bone graft.

To evaluate the clinical and radiological outcomes of lumbar spondylolisthesis treated with decompression and instrumented fusion using local autogenous bone graft.

This retrospective observational study was conducted in the Department of Orthopaedic Surgery, IBN Sina Medical College Hospital, Dhaka, Bangladesh. The study period extended from April 2021 to March 2025, and all eligible cases were reviewed retrospectively.

A total of consecutive patients who underwent surgery for lumbar spondylolisthesis during the study period were screened. After applying eligibility criteria, 45 patients were included in the final analysis. Patients excluded from the study included those with incomplete follow-up data or missing radiological/clinical records.

Ethical approval for this retrospective study was obtained from the Institutional Review Committee of IBN Sina Medical College Hospital. As this was a chart-based retrospective study, informed consent was waived in accordance with institutional policy.

Table 1. Baseline demographic and clinical characteristics of the study population (n = 45).

The study included 45 patients with a mean age of 51.1 ± 13.8 years (range 25 - 80 years) and an almost equal sex distribution (48.9% male, 51.1% female). The mean duration of symptoms was 10.1 ± 5.9 years. The median follow-up duration was 30 months (range 12 - 60 months). The mean postoperative hospital stay was 3.8 ± 0.7 days. Most patients underwent single-level fusion (88.9%), while 11.1% required multi-level fusion (Table 1).

Table 2. Distribution of spondylolisthesis according to level and meyerding grade (n = 45).

The L4-L5 level was the most commonly affected segment (25 patients, 55.6%), followed by L5-S1 (14 patients, 31.1%), L3-L4 (2 patients, 4.4%), and multi-level involvement (4 patients, 8.9%). According to Meyerding grading, Grade II spondylolisthesis was most frequent (29 patients, 64.4%), followed by Grade I (10 patients, 22.2%) and Grade III (6 patients, 13.3%) (Table 2).

Table 3. Clinical outcomes based on VAS and ODI scores (n = 45).

There was a marked improvement in clinical outcomes following surgery. The mean VAS score improved from 8.2 ± 1.1 preoperatively to 1.6 ± 0.8 at final follow-up, with a mean improvement of 6.6 points (p < 0.001). Similarly, the mean ODI score decreased from 49.1 ± 8.4 to 16.3 ± 6.8, with a mean improvement of 32.8% (p < 0.001) (Table 3).

Table 4. Slip percentage improvement after surgery (n = 45).

Radiological assessment demonstrated a significant reduction in slip percentage from 33.1 ± 8.2% preoperatively to 12.2 ± 4.5% at final follow-up, corresponding to a mean improvement of 20.9 ± 5.8% (p < 0.001). Overall slip improvement was 63.1 ± 11.8% (Table 4).

Figure 1. Fusion outcome according to Bridwell radiological criteria (n = 45).

Successful fusion was achieved in the majority of patients. Grade I fusion was observed in 36 patients (80.0%), Grade II in 7 patients (15.6%), Grade III in 1 patient (2.2%), and Grade IV in 1 patient (2.2%). Overall successful fusion (Grade I - II) was achieved in 43 patients (95.6%) (Figure 1).

Table 5. Fusion outcome according to Modified Lee’s criteria (n = 45).

According to Modified Lee’s criteria, definitive fusion was achieved in 36 patients (80.0%), possible fusion in 7 patients (15.6%), and pseudoarthrosis or failed fusion in 2 patients (4.4%) (Table 5).

Table 6. Fusion rate stratified by preoperative meyerding grade (n = 45).

Fusion rates were highest in Grade I and Grade III spondylolisthesis (100% each), while Grade II patients demonstrated a slightly lower fusion rate of 93.1% (27 out of 29 patients) (Table 6).

Table 7. Radiological changes in spinal alignment and disc parameters (n = 45).

Significant postoperative improvements were observed in all radiological parameters. Slip angle decreased from 18.9 ± 4.1˚ to 9.6 ± 2.9˚, disc height increased from 6.4 ± 1.3 mm to 9.3 ± 1.1 mm, and foraminal height improved from 13.6 ± 2.1 mm to 16.5 ± 1.8 mm (all p < 0.001) (Table 7).

Table 8. Postoperative complications (n = 45).

Postoperative complications occurred in 4 patients (8.9%). Adjacent segment disease and pseudarthrosis were observed in 2 patients each (4.4%), while deep infection occurred in 1 patient (2.2%). One patient experienced both pseudarthrosis and deep infection (Table 8). No cases of neurological deficit, implant failure, or donor-site morbidity were observed.

In this retrospective observational study conducted at the Department of Orthopaedic Surgery, IBN Sina Medical College Hospital, Dhaka, 45 patients with lumbar spondylolisthesis treated with posterior decompression and pedicle screw-rod fixation using local autogenous bone graft were evaluated for clinical and radiological outcomes. Most patients presented with degenerative, low- to moderate-grade disease, predominantly involving the L4-L5 level, with significant baseline pain and functional disability. Postoperative assessment demonstrated marked improvement in VAS and ODI scores, substantial reduction in slip parameters, and high rates of radiological fusion with minimal complications, indicating favorable clinical and radiological outcomes following local autograft-based instrumented fusion.

The baseline demographic and clinical profile of the present cohort is consistent with previously published studies on lumbar spondylolisthesis treated with pedicle screw fixation and local autogenous bone graft. The mean age of 51.1 ± 13.8 years (range 25 - 80 years) reflects the typical middle-aged to elderly population seen in degenerative spondylolisthesis, where progressive segmental instability and disc degeneration predominate. Similar findings have been reported by Lee et al. [16] and Tattari et al. [17], who also noted a predominance of middle-aged adults, L4-L5 involvement, and single-level fusion in most cases. In the present study, the long symptom duration and high proportion of single-level fusion (88.9%) further support a chronic, localized disease pattern. The median follow-up duration of 30 months (12 - 60 months) and short postoperative hospital stay reflect adequate long-term assessment and contemporary perioperative care. Overall, the similarity of baseline characteristics with prior literature supports the external validity of this cohort and strengthens interpretation of the clinical and radiological outcomes.

The distribution of spondylolisthesis levels and preoperative Meyerding grades in the present study is consistent with previously reported patterns in patients undergoing instrumented fusion with local autogenous bone grafting. In our cohort, L4-L5 was the most frequently affected level (55.6%), followed by L5-S1 (31.1%), while L3-L4 involvement and multi-level disease were comparatively uncommon. Similarly, Grade II spondylolisthesis was the predominant preoperative severity (64.4%), with fewer patients presenting with Grade I (22.2%) and Grade III (13.3%) slips. These findings closely align with the results reported by Yang et al. [7], who demonstrated that degenerative spondylolisthesis treated with posterior transforaminal lumbar interbody fusion using local autogenous morselized bone graft most commonly involves the L4-L5 level, followed by L5-S1, reflecting the biomechanical vulnerability of the lower lumbar segments. They also observed a predominance of low-grade (Meyerding Grade I-II) slips, with Grade II being the most frequent, which is in agreement with the present study. Overall, this consistency supports the well-established understanding that degenerative spondylolisthesis predominantly affects the L4-L5 segment and usually presents as low-grade instability, making it amenable to decompression and instrumented fusion with local autograft.

The present study demonstrated a marked and statistically significant improvement in clinical outcomes following lumbar decompression and instrumented fusion using local autogenous bone graft for spondylolisthesis. The mean VAS score improved from 8.2 ± 1.1 preoperatively to 1.6 ± 0.8 at final follow-up, while ODI decreased from 49.1 ± 8.4% to 16.3 ± 6.8%, reflecting substantial pain relief and functional restoration. These findings are consistent with previously published studies evaluating similar surgical techniques. Rayhan et al. [3] reported comparable results in patients with low-grade lumbar spondylolisthesis treated with decompression, pedicle screw fixation, and local bone grafting, where VAS improved from approximately 7 - 8 preoperatively to around 2 postoperatively, and ODI decreased from about 55 - 60% to 15 - 20%, along with favorable fusion outcomes. Similarly, Subramanian et al. [18] demonstrated significant clinical benefit following pedicle screw-assisted interbody fusion, with VAS reduction from 7 - 8 to nearly 2 and ODI improvement from approximately 60% to 18%, highlighting the effectiveness of stable segmental fixation in restoring spinal alignment and relieving neural compression. The consistency of these findings with the present study reinforces that local autogenous bone grafting combined with instrumented fusion provides reliable pain relief and functional improvement in degenerative spondylolisthesis, with outcomes comparable to established surgical series.

The present study demonstrated a significant radiological correction of vertebral slip following decompression and instrumented fusion using local autogenous bone graft for spondylolisthesis. The mean slip percentage improved from 33.1 ± 8.2% preoperatively to 12.2 ± 4.5% at final follow-up, corresponding to a mean reduction of 20.9 ± 5.8% and an overall slip improvement of 63.1 ± 11.8%, indicating sustained restoration of sagittal alignment. These findings are consistent with previously reported outcomes in the literature. Hagenmaier et al. [19] demonstrated that instrumented lumbar fusion leads to a significant reduction in vertebral slip from approximately 25% preoperatively to 15 - 17% postoperatively, with maintenance of correction over long-term follow-up, highlighting the stability achieved with posterior instrumentation. Similarly, Isogai et al. [20] reported a progressive reduction in slip percentage from a mean of about 21% preoperatively to 11% after interbody fusion and further improvement to approximately 4% following pedicle screw fixation, achieving an overall correction rate of nearly 80%, with sustained alignment at follow-up. The comparable magnitude of correction observed in the present study reinforces that rigid posterior fixation combined with fusion using local autogenous bone graft effectively restores and maintains vertebral alignment in degenerative spondylolisthesis.

The present study demonstrated a high rate of radiological fusion following posterior decompression and instrumented fixation with local autogenous bone graft for spondylolisthesis, as assessed by the Bridwell grading system. Grade I fusion was achieved in 80.0% of patients, Grade II in 15.6%, while only a small proportion exhibited Grade III (2.2%) and Grade IV (2.2%) outcomes, resulting in an overall successful fusion rate (Grade I - II) of 95.6%. These findings are consistent with previously published evidence. Zhao et al. [21], using the same Bridwell criteria, reported successful fusion (Grade I - II) in approximately 85 - 95% of patients, with Grade I being the most frequent outcome and higher-grade nonunion (Grade III - IV) occurring in less than 10% of cases. The close agreement between the present study and Zhao et al. [21] reinforces the reliability of pedicle screw-assisted fusion in achieving solid arthrodesis, particularly when supplemented with local autogenous bone graft harvested during decompression.

The fusion outcomes using Modified Lee’s criteria further demonstrate a high rate of successful arthrodesis. In the present study, definitive fusion was achieved in 80.0% of patients, with an additional 15.6% showing possible fusion, while pseudoarthrosis or failed fusion was observed in only 4.4% of cases. These findings are consistent with Rao et al. [22], who reported a combined definitive and probable fusion rate of approximately 91.7%, with pseudoarthrosis occurring in a small minority of cases (~8%). Similarly, Sleem et al. [4] observed that the majority of patients undergoing instrumented fusion for degenerative spondylolisthesis achieved solid fusion, with only a limited proportion showing possible fusion and rare pseudoarthrosis. Collectively, these studies reinforce that local autogenous bone grafting combined with rigid posterior instrumentation yields reliably high fusion rates, with most patients achieving definitive or near-definitive radiological union.

The stratified fusion outcomes according to preoperative Meyerding grade demonstrate uniformly high fusion success across all grades of spondylolisthesis. Grade I and Grade III patients achieved a 100% fusion rate, while Grade II patients demonstrated a slightly lower but still excellent fusion rate of 93.1%. These findings are in close agreement with Bydon et al. [23], who reported overall solid fusion rates of approximately 91 - 92%, with near-complete union in lower-grade slips and persistently high fusion success even in higher-grade cases when rigid fixation was used. This reinforces that when stable posterior instrumentation is achieved, preoperative slip grade has minimal influence on final fusion outcome.

The present study demonstrates significant postoperative radiological improvement in spinal alignment and disc space parameters following decompression and pedicle screw fixation with local autogenous bone grafting. There was a marked reduction in slip angle from 18.9 ± 4.1˚ to 9.6 ± 2.9˚, along with significant increases in disc height (6.4 ± 1.3 mm to 9.3 ± 1.1 mm) and foraminal height (13.6 ± 2.1 mm to 16.5 ± 1.8 mm), with all changes reaching statistical significance (p < 0.001). These findings closely align with Abou-Madawi et al. [14], who similarly reported significant postoperative restoration of slip percentage, disc height, segmental alignment, and foraminal dimensions following instrumented fusion. Furthermore, a recent systematic review and meta-analysis by Tavares et al. [24], including 64 studies comparing graft types in lumbar fusion, demonstrated that local bone graft achieved the highest fusion proportion (~95%), exceeding iliac crest autograft (~88%) and allograft groups. The consistency across studies highlights the biomechanical effectiveness of posterior stabilization with local autograft in restoring disc space height and achieving reliable fusion outcomes.

The complication profile in the present study demonstrates a relatively low overall morbidity following surgery. Adjacent segment disease and pseudarthrosis were each observed in 4.4% of patients, while deep infection occurred in 2.2%. One patient experienced both pseudarthrosis and deep infection. Importantly, no neurological deficits, implant failures, or donor site morbidity were observed. These findings are consistent with Booth et al. [25], who similarly reported very low complication rates following instrumented lumbar fusion, with rare pseudarthrosis, low infection rates, and negligible neurological complications. Overall, the comparable safety profile supports the use of local autograft as a reliable and low-morbidity option in instrumented fusion for degenerative spondylolisthesis.

The study had a few limitations:

•Small sample size (n = 45), which may limit the statistical power and generalizability of the findings.

•Single-center study, which may limit external validity across different populations and surgical settings.

Lumbar spondylolisthesis is a common degenerative spinal condition that often requires surgical stabilization when symptoms and instability progress. In this study, decompression with instrumented fusion using local autogenous bone graft demonstrated excellent clinical and radiological outcomes, with marked improvement in pain and functional status after surgery. Radiological assessment showed significant correction of deformity and restoration of spinal alignment, along with improved disc and foraminal dimensions. High rates of solid fusion were achieved across all grades of spondylolisthesis, indicating reliable arthrodesis with this technique. Overall, complication rates were low and no major neurological or implant-related adverse events were observed. These findings suggest that local autogenous bone graft is an effective and safe option for achieving durable clinical recovery and stable fusion in the management of lumbar spondylolisthesis.