European Journal of Cardiovascular Medicine

Lumbar disc herniation (LDH) is among the most prevalent degenerative conditions of the lumbar spine, usually presenting with low back pain accompanied by radiating leg pain. When conservative management fails to provide relief, surgical treatment becomes necessary [1]. Over the past decades, minimally invasive lumbar discectomy has shown excellent long-term outcomes and has emerged as a preferred surgical option for LDH management [2–4].

Among these minimally invasive techniques, unilateral biportal endoscopy (UBE)—first described in the 1980s—has undergone continuous refinement [5]. Compared with conventional open surgery, UBE offers several advantages, including smaller incisions, reduced soft tissue damage, and quicker postoperative recovery, which have contributed to its growing popularity as a minimally invasive procedure for lumbar spine disorders [5]. This approach is increasingly applied for decompression in both lumbar spinal stenosis and LDH cases [6].

In patients with degenerative lumbar spondylolisthesis (DLS) occurring at the same vertebral level as disc herniation, spinal fusion is often recommended if segmental instability is present. Segmental instability is typically defined by a change greater than 20° at L5/S1, more than 15° at the adjacent cephalad level, or sagittal translation exceeding 4 mm on dynamic flexion–extension radiographs. When these findings are absent, the condition is termed stable DLS [7].

The optimal surgical approach for LDH associated with stable DLS remains debated. Even with minimally invasive posterior techniques, partial disruption of posterior supporting elements and removal of disc material can affect spinal stability and may result in postoperative iatrogenic instability at the operated segment.

Previous studies have shown that unilateral biportal endoscopic discectomy (UBED) provides effective pain relief, shorter hospitalization, and earlier mobilization in patients with LDH [8]. However, it remains uncertain whether patients with LDH and coexisting stable grade I DLS develop postoperative segmental instability following UBED. Therefore, the present study aimed to retrospectively evaluate the clinical and radiographic outcomes of patients diagnosed with LDH and concomitant grade I stable DLS who underwent UBED.

All procedures in this study adhered to the principles outlined in the Declaration of Helsinki. Ethical approval for the study was obtained from the Institutional Ethics Committee of MKCG Medical College and Hospital, Berhampur, Odisha. As this was a retrospective study based on existing medical records, the requirement for informed patient consent was waived.

Inclusion criteria:

1.       Patients aged >18 years.

2.       Diagnosed with lumbar disc herniation (LDH) presenting with low back pain and radiating leg pain.

3.       Diagnosed with grade I degenerative lumbar spondylolisthesis (DLS) at the same spinal segment based on the Meyerding classification, without radiological evidence of intervertebral instability on dynamic flexion–extension imaging.

4.       Persistent symptoms for more than 12 weeks despite adequate conservative management.

5.       Underwent single-level unilateral biportal endoscopic discectomy (UBED) with at least 12 months of postoperative follow-up.

Exclusion criteria:

1.       Patients with LDH without DLS, multilevel LDH, or recurrent herniation.

2.       Cases of DLS with segmental instability, non-degenerative causes of spondylolisthesis, or grade ≥ II spondylolisthesis.

3.       Patients who underwent fusion procedures.

4.       Presence of cauda equina syndrome, scoliosis, spinal tumors, or infectious pathology.

To illustrate the procedure, the case of an L4–L5 left-sided disc herniation with stable grade I degenerative L4 spondylolisthesis is described.

Following the induction of general anesthesia, the patient was positioned prone with the abdomen free to minimize venous congestion. The operative level was confirmed using C-arm fluoroscopy, and the surgeon was positioned on the side of the lesion.

Two small (approximately 1.5 cm) incisions were made lateral to the midline: The cranial incision was used for endoscope insertion and continuous saline irrigation, located at the inferior margin of the upper lamina and; The caudal incision was used for instrument insertion and saline outflow, positioned at the superior margin of the lower lamina.

Sequential dilators were used to gently separate the paraspinal muscles, followed by removal of soft tissue using radiofrequency ablation to expose the lamina. After reconfirming the operative segment, the interlaminar space was identified. Partial resection of the inferior articular process of L4 and laminae of the adjacent vertebrae was performed using a Kerrison rongeur or osteotome to expose the ligamentum flavum, which was then carefully dissected and removed.

Once the epidural fat and nerve root were visualized, the herniated disc material was excised using pituitary forceps under direct endoscopic visualization. Adequate decompression was confirmed by the free mobility of the nerve root. A drain was inserted, and both incisions were closed in layers.

Radiographic and clinical data were collected preoperatively and at the final follow-up. Vertebral slippage percentage, Disc height (DH), Pain intensity and Functional. The question related to sexual function was omitted due to cultural sensitivity among elderly participants in this region. The ODI score was expressed as a percentage, calculated by dividing the total obtained score by the maximum possible score (45), where 0% indicated no disability and 100% indicated maximal disability.

Demographic and perioperative parameters including age, sex, weight, operated level, operative time, intraoperative and postoperative complications, time to first ambulation, hospital stay duration, and follow-up period were retrieved from hospital medical records. Continuous variables were summarized as mean ± standard deviation (SD). Pre- and postoperative comparisons of vertebral slippage percentage, disc height, VAS scores, and ODI scores were analyzed using the paired sample t-test. A p-value < 0.05 was considered statistically significant. All statistical analyses were conducted using R statistical software (version 4.3.0; R Foundation for Statistical Computing, Vienna, Austria).

A total of 55 patients who met the inclusion criteria were enrolled in the study. The cohort consisted of 16 males and 39 females, with a mean age of 71.4 ± 8.6 years and an average body weight of 60.2 ± 8.8 kg. The most frequently operated level was L4–L5 (83.6%), followed by L5–S1 (12.7%) and L3–L4 (3.6%). The mean operative duration was 88.9 ± 12.3 minutes, and the average hospital stay was 5.7 ± 1.8 days. The mean follow-up period was 22.6 ± 9.2 months.
(Table 1)

Table 1. Demographic and Clinical Characteristics of the Study Participants (n = 55)

Preoperative and postoperative radiological evaluations demonstrated stable outcomes after UBED. The mean slippage percentage increased slightly from 10.8 ± 2.9% preoperatively to 11.4 ± 3.1% at the final follow-up, which was not statistically significant (p = 0.092), indicating that no segmental instability developed postoperatively. The mean disc height showed a minimal reduction from 9.2 ± 1.3 mm preoperatively to 9.0 ± 1.4 mm at follow-up (p = 0.178), consistent with normal postoperative remodelling.

In terms of symptom improvement, both back pain and radiating leg pain significantly decreased following surgery. The mean VAS score for back pain improved from 6.8 ± 1.0 to 2.1 ± 0.9 (p < 0.001), and leg pain VAS improved from 7.4 ± 0.9 to 1.8 ± 0.8 (p < 0.001).

Functional recovery was also marked, with the mean Oswestry Disability Index (ODI) score improving from 63.5 ± 7.8% preoperatively to 20.7 ± 6.9% at final follow-up (p < 0.001).
Only three patients (5.5%) showed radiographic evidence of >5% slip progression, though none required revision or fusion surgery. (Table 2)

Table 2. Radiological and Clinical Outcomes of Patients (n = 55)

                Significant at p < 0.05.

The mean estimated blood loss during surgery was 68.4 ± 21.5 mL. Patients were mobilized early, with the average time to first ambulation recorded as 10.6 ± 3.2 hours, and drains were typically removed within 36.7 ± 8.4 hours postoperatively.

Intraoperative complications were minimal, including two dural tears (3.6%) and three cerebrospinal fluid (CSF) leaks (5.5%), all of which were managed conservatively without further sequelae. Postoperative complications included transient paresthesia in four patients (7.3%), superficial wound infection in two (3.6%), and a single case (1.8%) of epidural hematoma, which was successfully treated without surgical intervention. Only one patient (1.8%) required reoperation during follow-up due to recurrent symptoms.

The overall complication rate was 14.5%, and no cases of postoperative neurological deterioration, instrumentation failure, or mortality were observed. (Table 3)

Table 3. Perioperative Parameters and Postoperative Complications of Patients (n = 55)

This retrospective study included 55 patients diagnosed with lumbar disc herniation (LDH) and concomitant stable grade I degenerative lumbar spondylolisthesis (DLS) who underwent unilateral biportal endoscopic discectomy (UBED) at MKCG Medical College and Hospital, Berhampur, Odisha, with a mean follow-up duration of 22.6 months.

Following surgery, both back and leg pain improved significantly, accompanied by a marked enhancement in functional outcomes, as reflected in the postoperative reduction of VAS and ODI scores. Although there was a minor increase in the mean vertebral slip percentage and a slight decrease in disc height postoperatively, these radiological changes did not translate into clinical deterioration. Only three patients (5.5%) demonstrated mild slip progression (>5%), none of whom required reoperation. These findings support that UBED is a safe and effective surgical technique for elderly patients with LDH and stable DLS, providing substantial pain relief and functional recovery without inducing postoperative instability.

Over the past decades, surgical approaches for LDH have evolved from open discectomy to minimally invasive techniques that aim to minimize soft tissue trauma while maintaining decompressive efficacy [2,3]. Among these, UBE has gained wide acceptance due to its dual-channel visualization system, which enables clear endoscopic views and precise discectomy with minimal paraspinal muscle disruption [5,9–12]. Several studies have reported that UBED provides excellent long-term pain relief, improved functional recovery, and high patient satisfaction, comparable to traditional open discectomy [9–12].

Additionally, UBED can effectively manage both up-migrated and down-migrated disc fragments, allowing a broader operative field and reducing residual disc material [13,14].

When compared with other minimally invasive procedures, UBED has both strengths and limitations. Jiang et al. [15] compared UBED and percutaneous endoscopic lumbar discectomy (PELD) and found both achieved similar pain relief and satisfaction rates, though UBED was associated with slightly higher blood loss and longer operative times.

This difference was attributed to greater paraspinal muscle dissection and bony resection in UBED, while PELD better preserves posterior elements [16,17].

However, UBED offers a shorter learning curve and a more familiar surgical anatomy to spine surgeons accustomed to open discectomy techniques [9]. These features make UBED particularly advantageous in resource-limited tertiary hospitals, such as those in eastern India, where surgeon familiarity and safety are priorities.

The optimal surgical strategy for patients with LDH and coexisting DLS remains debated, particularly regarding the need for fusion procedures [18–20].

While fusion can prevent postoperative instability, it is associated with longer operative time, greater blood loss, and prolonged recovery [19,20]. Given that UBED involves partial removal of laminar and articular components, theoretical concerns exist regarding iatrogenic instability. However, our findings show that, in stable grade I DLS, decompression via UBED does not significantly compromise spinal stability.

In our series, the slight postoperative increase in slip percentage and reduction in disc height were statistically insignificant and clinically unremarkable. This pattern aligns with the “restabilization phase” of DLS, characterized by disc space narrowing, osteophyte formation, and ligament ossification, which may contribute to postoperative stability [7]. All patients resumed ambulation within 10–12 hours post-surgery, demonstrating that UBED allows early mobilization and short hospital stays, which are especially beneficial for elderly patients.

The overall complication rate in our study was 14.5%, which is comparable to previously reported UBED series [21,22]. Three patients (5.5%) experienced cerebrospinal fluid (CSF) leaks, likely secondary to unrecognized intraoperative dural microtears.

None required reoperation, and all resolved with conservative management.

Park et al. [21] reported similar findings, identifying thecal sac tears as the most common dural injury site during UBE procedures. A recent meta-analysis also highlighted dural tear as the most frequent complication, with an incidence of 2.9–5.8% [22], consistent with our data.

Other postoperative complications—such as transient paresthesia (7.3%) and superficial wound infection (3.6%)—were mild and self-limiting. The relatively short mean hospital stay (5.7 days) and early ambulation indicate favorable postoperative recovery and minimal morbidity.

Our study reinforces that UBED offers a practical, minimally invasive, and effective alternative to conventional discectomy in patients with LDH and stable DLS, particularly in older adults.

The approach minimizes muscle and tissue trauma, reduces recovery time, and achieves comparable long-term outcomes without the need for spinal fusion in carefully selected cases.

This is particularly valuable in Indian tertiary hospitals, where early ambulation, shorter hospitalization, and reduced surgical morbidity are crucial for optimizing bed turnover and resource utilization.

Limitations

This study has several limitations. First, the sample size (n = 55), although larger than prior single-center reports, remains modest, limiting the generalizability of results.

Second, radiological follow-up did not include dynamic flexion-extension radiographs for all patients, which might have underestimated subtle postoperative instability.

Third, this was a single-arm retrospective study, and outcomes were not directly compared with other minimally invasive techniques such as PELD or microdiscectomy.

Future prospective, multicentric studies with larger cohorts and longer follow-up durations are warranted to confirm these findings and determine long-term stability after UBED.

UBED offers a safe, effective, and minimally invasive alternative for managing lumbar disc herniation with concomitant stable grade I DLS. The procedure provides significant pain relief, functional improvement, minimal blood loss, and early mobilization, with no significant postoperative instability. Given its adaptability, shorter learning curve, and minimal invasiveness, UBED may be considered an optimal surgical choice for elderly or comorbid patients in resource-limited settings like Berhampur, Odisha, and similar regions

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