Endoscopic excision of intervertebral disc herniations in the lumbar region

Summary

Introduction: Herniated disc is a common cause of lumbar radiculopathy. Full endoscopic discectomy is a minimally invasive alternative to microdiscectomy. The aim of the study was to evaluate the results and complications of endoscopic procedures and to compare the transforaminal and interlaminar approaches. Methods: A retrospective analysis included 64 patients (40 men, 24 women; mean age 51.2 years). Transforaminal approach was performed in 12 patients and interlaminar in 52 patients. In both groups, we evaluated the duration of surgery, X-ray exposure, Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) (before the procedure, at discharge, 3 and 12 months after surgery), postoperative complications, and the frequency of postoperative recurrence of herniated disc. Results: The mean duration of surgery was 62 min. X-ray exposure was longer with the transforaminal approach (43 s) than with the interlaminar approach (22 s; P < 0.001). VAS decreased from 7.4 ± 1.2 to 1.3 ± 0.8 at 12 months (P < 0.0001), and ODI from 56% ± 13% to 14% ± 9% (P < 0.0001). No significant difference was found between the transforaminal and translaminar approaches in VAS and ODI. The results are valid for the entire group of patients. The overall complication rate was 14.0%. We recorded dural sac injuries twice (3.1%) without the need for surgical revision. Recurrence of disc herniation was recorded in 7 patients (10.9%). Conclusion: Transforaminal and translaminar endoscopic extirpation of intervertebral disc herniation is an effective and safe method with rapid recovery and low morbidity. The translaminar approach is suitable for centrolateral herniations, where it allows a more direct and anatomically clearer approach to the pathology with better control of the dural sac and nerve root and is associated with lower technical demands. The transforaminal approach is used for medial and laterally localized intervertebral disc herniations. The advantage is the preservation of the integrity of the spinal canal with minimal manipulation of the dural sac. However, it is technically more demanding and the result depends on the experience of the surgeon.

Keywords:

Endoscopic surgery – interlaminar approach – herniated intervertebral disc – transforaminal approach

This is an unauthorised machine translation into English made using the DeepL Translate Pro translator. The editors do not guarantee that the content of the article corresponds fully to the original language version.

Introduction

Lumbar disc herniation (LDH) is one of the most common causes of lumbar radiculopathy and represents a significant health and socioeconomic problem [1]. The prevalence of symptomatic intervertebral disc herniation is estimated at 1–3% of the adult population, with a peak between the ages of 30 and 50. Pathophysiologically, it involves a degenerative disc process characterized by loss of hydration in the nucleus pulposus, a reduction in proteoglycan content, and weakening of the annulus fibrosus [2,3]. Protrusion or extrusion of disc material into the spinal canal leads to compression of neural structures and triggers an inflammatory cascade, which clinically manifests as back pain, radicular pain, and, in some cases, motor deficits [4,5]. Conservative treatment is the first-line approach; however, persistent symptoms or progression of neurological deficits are indications for surgical treatment [6].

Traditional open discectomy has been and continues to be regarded as the gold standard. It still has its place in the surgical treatment of lumbar disc herniations [7]. Advances in minimally invasive techniques have led to the introduction of fully endoscopic discectomy, which achieves results comparable to those of microdiscectomy with less invasiveness [8,9]. In the monoport technique, two main approaches are used—transforaminal and interlaminar. The transforaminal approach is particularly suitable for centrally and laterally located sequesters, while the interlaminar approach is suitable for centrolaterally located sequesters and for the L5/S1 segment, which is difficult to reach via the transforaminal approach [10]. Endoscopic spinal surgery today encompasses not only monoportal systems but also biportal endoscopic techniques, which combine a separate working and optical port. The biportal approach allows for greater freedom of instrumentation, better orientation within the surgical field, and more effective decompression of neural structures. As a result, it is possible to treat not only intervertebral disc herniations endoscopically but also a broader spectrum of degenerative diseases, including central and lateral lumbar spinal stenosis.

The aim of this study is to present our experience with monoportal endoscopic excision of intervertebral disc herniations in the lumbar region, analyze clinical outcomes and complications, and compare both endoscopic approaches.

 

Materials and Methods

A total of 64 patients (40 men, 24 women; mean age 51.2 years) who underwent endoscopic excision of intervertebral disc herniations were included in the retrospective analysis. All patients presented with clinical symptoms of radiculopathy, corresponding findings on MRI, and persistent symptoms following at least 6 weeks of conservative therapy. Exclusion criteria included an unstable segment, significant spinal canal stenosis, and cauda equina syndrome [11]. No explicit age limits were predetermined in the study; patient inclusion was assessed on an individual basis, taking into account overall clinical condition and the suitability of the chosen surgical approach. For anatomical reasons, patients with a migrating sequestrum, significant central spinal canal stenosis, or anatomical conditions precluding safe endoscopic access were excluded from the study.

The surgical procedures were performed by two surgeons. The initial portion of the cohort included procedures performed during the early phase of mastering the technique, while standardization of the surgical procedure was maintained throughout the study. The surgeries were performed under general anesthesia with antibiotic prophylaxis. The patient was positioned prone with pelvic support and the lower limbs flexed on the operating table. A fully endoscopic monoportal system was used. For the transforaminal approach, access was gained from the lateral side under fluoroscopic guidance through Kambin’s triangle (Fig. 1). This was followed by the insertion of dilators and the working channel. Endoscopic forceps and a radiofrequency electrode were used to remove the herniated material (Fig. 2). The method is indicated for lateral, foraminous, and central herniations [12].

For the interlaminar approach, a working channel with an endoscope was inserted via a dorsal approach, approximately 1 cm from the midline on the side of the symptomatic herniation. Partial resection of the ligamentum flavum was performed, and the working channel was inserted directly into the interlaminar space, followed by transection of the posterior longitudinal ligament and excision of the herniated disc (Fig. 3). This approach is indicated for centrolateral herniations and allows for more comfortable access to the caudal levels, particularly L5–S1, where the iliac crest limits transforaminal endoscope insertion [13]. In the presence of spinal canal stenosis, a motorized burr was used for partial resection of bony structures. Perioperative data included procedure duration, blood loss, X-ray exposure, and postoperative complications. Postoperatively, length of hospital stay, return to work, and analgesic use were monitored. Clinical outcomes were assessed using the Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODI) before surgery, at discharge, and at 3 and 12 months [14]. Pain was assessed using the VAS, focusing on dominant radicular pain in the lower extremity, which was the primary clinical symptom leading to the indication for surgery. Patients’ functional status was assessed using the ODI, specifically version 2.0, as a comprehensive indicator of functional impairment.

Statistical analysis was performed using paired and unpaired t-tests; p < 0.05 was considered statistically significant [15]. Statistical analysis was performed using GraphPad Prism version 10.0 (GraphPad Software, San Diego, CA, USA).

 

Results

The study group consisted of 64 patients (40 men, 24 women) with a mean age of 51.2 years (range 27–73 years). A transforaminal approach was used in 12 patients, and an interlaminar approach in 52 patients. The percentage of endoscopic procedures compared to the total number of intervertebral disc surgeries in our cohort was 9.5%.

The average duration of the procedure was 62 minutes (65 minutes for the transforaminal approach, 61 minutes for the interlaminar approach). Blood loss was minimal (<50 ml). X-ray exposure was longer for the transforaminal approach (43 seconds) compared to the interlaminar approach (22 seconds, p < 0.001). The average length of hospital stay was 2.3 days (1–5 days). Most patients were able to stand on the day of surgery. Regular follow-up visits at the neurosurgical outpatient clinic took place at intervals of 6 weeks, 3, 6, and 12 months after surgery. An MRI of the lumbar region was routinely performed at 3 months.

The VAS score decreased from 7.4 ± 1.2 preoperatively to 2.1 at discharge, 1.6 at 3 months, and 1.3 at 12 months (p < 0.0001). The ODI improved from 56% to 18% at 3 months and 14% at 12 months (p < 0.0001) [16]. There was no significant difference in the final VAS or ODI scores between the transforaminal and interlaminar approaches. Patients younger than 50 years showed a faster decline in VAS and a faster return to work; however, the difference was not statistically significant.

Within 6 weeks, 52 patients (81.3%) returned to work, with an average return time of 6.1 weeks. Patients with physically demanding occupations returned to work an average of 2 weeks later.

Analgesic use decreased significantly as early as 1 week after the procedure, by which time most patients no longer needed to take analgesics regularly. At 12 months, only 9% of patients were taking analgesics regularly.

Complications were reported in 9 patients (14.0%). Durotomy was performed in 2 patients (3.1%) without the need for further revision. Recurrence of herniation indicated reoperation in 7 patients (10.9%) [17]. Early recurrence (≤ 6 months) occurred in 3 patients, and late recurrence (> 6 months) in 4 patients. Recurrences were more common with the interlaminar approach (6 cases) than with the transforaminal approach (1 case); the difference was not statistically significant [18]. No infections, deep vein thrombosis, or permanent neurological deficits were reported.

Follow-up MRI was routinely performed 3 months after surgery to assess any residual or recurrent herniated intervertebral disc; if clinical symptoms worsened, MRI was indicated on an individual basis as needed. In cases of confirmed recurrence and persistent symptoms, reoperation using a microsurgical technique was indicated. Prior to reoperation, in addition to standard MRI, dynamic X-rays were performed to rule out instability of the spinal segment.

 

Discussion

Our results confirm the high efficacy of endoscopic LDH excision, with a clearly significant improvement in pain and functional status as measured by the VAS and ODI. The results persisted even after 12 months, which is consistent with published meta-analyses and randomized studies reporting comparable or better outcomes compared to microdiscectomy [6–8,16]. Some earlier studies report a faster return to work after endoscopic discectomy compared to conventional microdiscectomy, which is attributed to the procedure’s lower invasiveness [19]. However, more recent comparative studies and meta-analyses do not confirm these differences and indicate comparable return-to-work times for both methods [20]. These results suggest that the choice of surgical technique alone may not be a decisive factor for the speed of return to work, which is likely influenced by other clinical and socioeconomic factors as well.

When comparing the transforaminal and interlaminar approaches, no significant differences in clinical outcomes were found, but the transforaminal approach was associated with longer X-ray exposure. Similar conclusions are drawn by international meta-analyses, which recommend the use of modern technologies to reduce radiation exposure, such as neuronavigation or 3D imaging systems [9,21]. The interlaminar approach was used more frequently in our cohort and showed a higher recurrence rate, which may be associated with biomechanical stress on the L5–S1 segment, but also with a learning curve, where an increased incidence of disc herniation recurrence is reported in the first fifty surgeries [22,23]. The overall complication rate in our cohort (14%) is comparable to published data [12–15,18,24].

The learning curve is a critical factor in the implementation of endoscopic surgery. Publications indicate that 30–50 procedures are required to achieve proficiency, particularly with the transforaminal approach [25]. As the surgeon’s experience increases, not only does operative time decrease, but so does the risk of complications. The introduction of the method should therefore take place in centers with an experienced instructor and careful preoperative planning.

A significant benefit of endoscopy is also reduced perioperative soft tissue trauma, which contributes to less postoperative pain and a faster return to normal activities. Meta-analyses also show a lower incidence of epidural scarring in endoscopic procedures, which may be an advantage in younger patients. Preservation of the ligamentum flavum in minimally invasive approaches may play a role in limiting the extent of epidural exposure and subsequent scar tissue formation. This factor could contribute to a lower risk of developing epidural fibrosis, which is considered one of the possible causes of persistent or recurrent postoperative complications [26,27].

In recent years, there has been dynamic development of endoscopic technologies in spinal surgery, with the biportal endoscopic approach increasingly being used alongside traditional monoportal systems. The biportal technique appears promising, particularly due to improved ergonomics, reduced soft tissue trauma, and a potentially smaller extent of laminectomy. However, these anticipated benefits are currently based primarily on early clinical experience and must be further confirmed in prospective studies with long-term follow-up.

When comparing microdiscectomy, monoportal endoscopy, and biportal endoscopy, all of these surgical methods yield better clinical outcomes than conservative treatment for symptomatic lumbar disc herniation. Surgical intervention leads to faster relief from radicular pain, improved functional status, and an earlier return to normal activities. However, achieving these results is fundamentally dependent on the correct indication for surgery, the correlation of clinical findings with imaging methods, and the appropriate selection of surgical technique [28].

Our results support the growing importance of endoscopic surgery in the treatment of intervertebral disc herniations and confirm that it is a fully valid alternative to microdiscectomy. The choice of approach should be individualized based on anatomical conditions, the type of herniation, and the surgeon’s experience [29].

 

Conclusion

Endoscopic excision of lumbar intervertebral disc herniation is an effective, minimally invasive, and safe method with significant improvement in pain and function. In our cohort, the complication rate was low, and outcomes were comparable between the transforaminal and interlaminar approaches. Endoscopic surgery represents a modern alternative to microdiscectomy, and its role in the treatment of lumbar discopathies continues to grow; however, microdiscectomy retains its established place in the surgical management of intervertebral disc herniations.

 

Ethical Aspects

The study was conducted in accordance with the 1975 Declaration of Helsinki and its revisions in 2004 and 2008 and was approved by the Ethics Committee of the University Hospital Ostrava (approval number: 384/2020, approval date: April 30, 2020).

 

Grant Support

This work was supported by institutional grant number 13/RVO-FNOs/2020.

 

Conflict of interest

The authors declare that they have no conflict of interest regarding the subject of the study.