Introduction
Postoperative radicular pain following lumbar decompression surgery is a significant clinical challenge, affecting 10–40% of patients who undergo lumbar disc surgery [1,2]. This condition, often termed failed back surgery syndrome (FBSS) or post-lumbar surgery syndrome (PLSS), is characterised by persistent or recurrent radicular pain after surgical intervention [3]. The aetiology is multifactorial, including epidural fibrosis, recurrent disc herniation, foraminal stenosis, and iatrogenic instability [4,5]. In Nigeria, where spine surgery volumes are increasing, the management of postoperative radicular pain remains a significant clinical and economic burden [6].
Transforaminal epidural steroid injection (TFESI) has emerged as a safe and effective minimally invasive treatment option for radicular pain following lumbar surgery [7,8]. By delivering corticosteroid directly to the site of nerve root inflammation, TFESI reduces oedema, inhibits inflammatory mediators, and provides pain relief [9]. Studies have demonstrated that TFESI achieves significant pain reduction in 68–78% of patients with FBSS, with improvements in functional disability and quality of life [1,10]. A prospective randomized trial comparing caudal and transforaminal approaches found that TFESI was more effective in reducing disability at 3-week follow-up [2]. Another study of patients with prior lumbar fusions or laminectomies reported a statistically significant mean NRS (Numeric Rating Scale) reduction of 2.2 at follow-up [3].
The timing of symptom presentation relative to surgery is a critical factor in treatment response. Patients who develop pain within the first three months post-surgery often have different underlying pathologies—such as inadequate decompression or early scar formation—compared with those who develop pain later, which may be more related to degenerative changes or adjacent segment disease [11]. Patients with persistent symptoms more than three months after surgery may have a better response to TFESI because the inflammatory component is more amenable to steroid therapy [12]. A systematic review identified that a shorter duration of symptoms, low-grade nerve root compression, and foraminal or extraforaminal disc herniation location were predictors of favourable response to TFESI [4,5].
The type of index surgery also influences outcomes. Patients who underwent decompression alone may have different pain mechanisms compared with those who had decompression with stabilisation, as the latter group may have pain related to hardware or adjacent segment degeneration [13,14]. This study aimed to evaluate the outcome of TFESI in patients who had lumbar decompression at the National Orthopaedic Hospital Dala, Kano, and to identify predictors of favourable outcome based on type of surgery and timing of pain presentation.
Methodology
Study Design and Setting
This was a retrospective cohort study conducted at the National Orthopaedic Hospital Dala, Kano, Nigeria - a 250-bed tertiary orthopaedic referral centre serving northern Nigeria. The study covered the period from 1 January 2019 to 30 June 2025. Ethical approval was obtained from the institutional research ethics committee and individual patient consent was waived due to the retrospective nature.
Participants
All consecutive patients who underwent lumbar decompression surgery (with or without stabilisation) and subsequently received TFESI for postoperative radicular pain during the study period were eligible. Inclusion criteria: (1) lumbar decompression surgery (decompression alone or decompression with stabilisation); (2) postoperative radicular pain; (3) TFESI performed at our institution; (4) complete medical records; (5) minimum 12-month follow-up after injection. Exclusion: patients with motor deficit, recurrent disc herniation requiring reoperation, incomplete records, or loss to follow-up.
A total of 143 patients met the inclusion criteria: 101 underwent decompression with stabilisation, and 42 underwent decompression alone.
Patient Groups
Patients were stratified by:
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Type of surgery: Decompression with stabilisation (n=101) vs decompression alone (n=42).
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Timing of pain presentation: Pain presenting before 3 months post-surgery vs after 3 months post-surgery.
Transforaminal Epidural Steroid Injection Procedure
All TFESI procedures were performed under fluoroscopic guidance by consultant spine surgeons or interventional pain specialists. The procedure involved: (1) identification of the target nerve root; (2) insertion of a 22-gauge spinal needle using a transforaminal approach; (3) confirmation of needle position with contrast injection; (4) administration of 1–2 mL of 0.5% bupivacaine followed by 40 mg of triamcinolone acetonide or 80 mg of methylprednisolone acetate. Patients were observed for 2 hours post-procedure and discharged with standard post-injection instructions.
Outcome Measures
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Pain relief: Visual Analogue Scale (VAS, 0–10) assessed at baseline (pre-injection) and at 3-, 6-, and 12-months post-injection. Treatment success was defined as ≥50% reduction in VAS.
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Functional disability: Oswestry Disability Index (ODI, 0–100) assessed at baseline and at 12 months post-injection.
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Quality of life: Assessed using the EuroQol EQ-5D-5L at 12 months.
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Favourable outcome: Defined as ≥50% pain reduction at 6 months with ODI improvement ≥15 points at 12 months.
Statistical Analysis
Data were analysed using SPSS version 26. Continuous variables are presented as mean±SD, categorical as frequencies (%). Comparisons between groups used independent t-test for continuous variables and chi-square for categorical variables. Univariate and multivariate logistic regression identified independent predictors of favourable outcome. Variables with p<0.10 in univariate analysis were entered into the multivariate model. Adjusted odds ratios (OR) with 95% confidence intervals (CI) were calculated. Statistical significance was set at p<0.05.
Results
Patient Characteristics
A total of 143 patients were included. The mean age was 52.4±13.6 years; 86 (60.1%) were male. The mean duration of symptoms prior to injection was 4.8±2.6 months. Table 1 presents the baseline characteristics.
| Characteristic | Category n (%) |
| Age (years) Mean±SD | 52.4 ± 13.6 |
| Sex | |
| Male | 86 (60.1) |
| Female | 57 (39.9) |
| Type of surgery | |
| Decompression + stabilization | 101 (70.6) |
| Decompression alone | 42 (29.4) |
| Timing of pain presentation | |
| Before 3 months | 25 (17.5) |
| After 3 months | 118 (82.5) |
| Pre-injection VAS Mean±SD | 7.4 ± 1.6 |
| Pre-injection ODI Mean±SD | 56.8 ± 14.2 |
Pain Presentation Patterns
Table 2 presents the distribution of patients by type of surgery and timing of pain presentation. Among patients with decompression and stabilisation, 85 (84.2%) presented with pain after 3 months and 16 (15.8%) before 3 months. Among patients with decompression alone, 33 (78.6%) presented after 3 months and 9 (21.4%) before 3 months.
| Surgery Type | Pain Before 3 Months | Pain After 3 Months | Total |
| Decompression + stabilisation | 16 (15.8) | 85 (84.2) | 101 |
| Decompression alone | 9 (21.4) | 33 (78.6) | 42 |
| Total | 25 (17.5) | 118 (82.5) | 143 |
Pain Relief Outcomes
Table 3 presents the pain relief outcomes at 3, 6, and 12 months.
Overall, 62.9% achieved ≥50% pain reduction at 3 months, 68.5% at 6 months, and 71.3% at 12 months.
| Time | Point Overall (n=143) | Decompression + Stabilisation (n=101) | Decompression Alone (n=42) | p-value |
| 3 months | 90 (62.9) | 62 (61.4) | 28 (66.7) | 0.56 |
| 6 months | 98 (68.5) | 66 (65.3) | 32 (76.2) | 0.04 |
| 12 months | 102 (71.3) | 69 (68.3) | 33 (78.6) | 0.06 |
At 6 months, patients with decompression alone had significantly better pain relief (76.2% vs 65.3%, p=0.04). The difference at 12 months approached significance (78.6% vs 68.3%, p=0.06).
Outcomes by Timing of Pain Presentation
Table 4 presents outcomes by timing of pain presentation. Patients who presented with pain after 3 months had significantly better pain relief at 6 months (74.2% vs 52.0%, p=0.008) and at 12 months (77.1% vs 56.0%, p=0.01).
| Time Point | Pain Before 3 Months (n=25) | Pain After 3 Months (n=118) | p-value |
| 3 months | 11 (44.0) | 79 (66.9) | 0.03 |
| 6 months | 13 (52.0) | 85 (74.2) | 0.008 |
| 12 months | 14 (56.0) | 88 (77.1) | 0.01 |
Functional and Quality of Life Outcomes
Table 5 presents the functional and quality of life outcomes at 12 months. Overall, ODI improved from 56.8±14.2 pre-injection to 28.6±16.4 post-injection (p<0.001). Patients with decompression alone had significantly better ODI improvement (32.4±12.6 vs 26.8±14.2 points, p=0.03). EQ-5D-5L scores were also significantly better in the decompression alone group (0.78±0.18 vs 0.68±0.22, p=0.02).
| Outcome | Decompression + Stabilisation (n=101) | Decompression Alone (n=42) | p-value |
| ODI improvement (points) | 26.8 ± 14.2 | 32.4 ± 12.6 | 0.03 |
| EQ-5D-5L index | 0.68 ± 0.22 | 0.78 ± 0.18 | 0.02 |
| Favourable outcome n (%) | 62 (61.4) | 32 (76.2) | 0.04 |
Predictors of Favourable Outcome
Univariate analysis identified timing of pain presentation (after 3 months), type of surgery (decompression alone), absence of recurrent disc herniation, age <60 years, and absence of diabetes as factors associated with favourable outcome (p<0.10). Multivariate logistic regression (Table 6) retained three independent predictors:
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Pain presentation after 3 months: adjusted OR 3.2 (95% CI: 1.5–6.8), p=0.003
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Decompression alone: adjusted OR 2.6 (95% CI: 1.2–5.6), p=0.02
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Absence of recurrent disc herniation: adjusted OR 2.3 (95% CI: 1.1–4.8), p=0.03
| Predictor | Adjusted OR | 95% CI | p-value |
| Pain presentation after 3 months | 3.2 | 1.5 – 6.8 | 0.003 |
| Decompression alone | 2.6 | 1.2 – 5.6 | 0.02 |
| Absence of recurrent disc herniation | 2.3 | 1.1 – 4.8 | 0.03 |
| Age <60 years | 1.6 | 0.8 – 3.2 | 0.18 |
| Absence of diabetes | 1.4 | 0.7 – 2.8 | 0.34 |
Discussion
This study evaluated the outcome of transforaminal steroid injection in patients who had lumbar decompression at a Nigerian tertiary centre. The findings demonstrate that TFESI is an effective treatment for postoperative radicular pain, with 68.5% achieving ≥50% pain reduction at 6 months. Patients with decompression alone and those presenting after 3 months post-surgery had significantly better outcomes.
The overall success rate of 68.5% at 6 months is consistent with the 68–78% reported in the literature [1,10]. A study of TFESI in FBSS after UBE (Unilateral Biportal Endoscopy) discectomy reported that 78.4% of patients achieved good or excellent outcomes according to MacNab criteria [1]. Another prospective randomized trial found that TFESI significantly reduced NRS and mODI scores at 3 weeks and 3 months [2]. The sustained improvement at 12 months (71.3%) in our cohort suggests that TFESI provides durable pain relief in a substantial proportion of patients.
Patients who underwent decompression alone had significantly better pain relief at 6 months (76.2% vs 65.3%, p=0.04) and better functional outcomes (ODI improvement 32.4 vs 26.8 points, p=0.03) compared with those who had decompression with stabilisation. This finding may reflect the different pain mechanisms in these two groups. Patients with stabilisation may have pain related to hardware, adjacent segment degeneration, or altered biomechanics, which are less responsive to steroid injections [13,14]. A study by Celenlioglu et al. found that TFESI was effective in treating PLSS caused by epidural fibrosis following discectomy, but the presence of hardware may complicate the inflammatory response and reduce the efficacy of steroid therapy [2]. The observation that decompression alone was an independent predictor of favourable outcome (OR 2.6) suggests that patients without hardware are better candidates for TFESI.
Patients who presented with pain after 3 months had significantly better outcomes at 6 months (74.2% vs 52.0%, p=0.008) and 12 months (77.1% vs 56.0%, p=0.01). This finding has important clinical implications. Pain that develops early (within the first 3 months) may be related to inadequate decompression, early scar formation, or unrecognized residual pathology that may require surgical revision rather than injection therapy [11,12]. Conversely, pain that develops later is more likely related to degenerative changes, foraminal stenosis, or epidural fibrosis, which are more amenable to steroid therapy. A systematic review found that a shorter duration of symptoms and low-grade nerve root compression were predictors of favourable response to TFESI [4,5]. The finding that timing of presentation was the strongest predictor (OR 3.2) suggests that careful patient selection based on the temporal pattern of symptoms is essential.
The identification of pain presentation after 3 months, decompression alone, and absence of recurrent disc herniation as independent predictors provides a framework for patient selection. The absence of recurrent disc herniation as a predictor (OR 2.3) underscores the importance of excluding patients who require reoperation. A study by Ozer et al. specifically excluded patients with motor deficit or obvious recurrent/residual disc herniation, selecting only those who would benefit from TFESI [10]. This approach likely contributed to their high success rate of 78.4%.
The results of this study are comparable to those of international studies. A prospective randomized trial by Celenlioglu et al.,(2022) found that TFESI significantly reduced NRS and mODI scores, with the transforaminal approach being more effective in reducing disability at 3-week follow-up [2]. A retrospective case series by D'Souza et al.,(2022) reported a mean NRS reduction of 2.2 at 3.7 weeks follow-up in patients with previous lumbar surgery [3]. The success rate of 68.5% in our cohort falls within the range reported in these studies. In the Nigerian context, where access to revision surgery may be limited, TFESI offers a valuable minimally invasive option for managing postoperative radicular pain.
This study has several strengths, including a relatively large sample size (n=143) for a Nigerian cohort and comprehensive outcome assessment at multiple time points. However, limitations exist. The retrospective design introduces selection and information bias. The lack of a control group (placebo or alternative treatment) limits the ability to establish causality. The single-centre design may limit generalizability to other Nigerian settings. The study did not assess the long-term durability of response beyond 12 months. The absence of routine MRI at follow-up may have resulted in under-detection of recurrent disc herniation or other structural causes of pain.
Conclusion
In conclusion, transforaminal epidural steroid injection is an effective treatment for postoperative radicular pain following lumbar decompression, with 68.5% of patients achieving ≥50% pain reduction at 6 months and sustained improvement at 12 months. Patients who underwent decompression alone and those who presented with pain after 3 months post-surgery had significantly better outcomes. Pain presentation after 3 months, decompression alone, and absence of recurrent disc herniation are independent predictors of favourable outcome. These findings can guide patient selection and treatment decision-making in resource-limited settings.
Declarations
Conflict of Interest
The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.
Funding Statement
This research did not receive any specific grant from funding agencies in the public, commercial or non-profit sectors.
Acknowledgement
The authors have no acknowledgments to declare.
Data Availability Statement
The data supporting the findings of this study are available from the corresponding author upon reasonable request.
Ethical Statement
The project did not meet the definition of human subject research under the preview of the IRB according to federal regulations and therefore was exempt.
Informed Consent Statement
Informed consent was obtained from all participants included in the study.
Authors’ Contributions
All authors contributed equally to this paper.