Endoscopic disc surgery (EDS) for lumbar spine disc herniation is a well-known but developing field, which is increasingly spreading in the last few years. Rate of recurrence/residual, complications, and outcomes, in comparison with standard microdiscectomy (MD), is still debated and need further data. We performed an extensive review based on the last 6 years of surgical series, systematic reviews, and meta-analyses reported in international, English-written literature. Articles regarding patients treated through endoscopic transforaminal or interlaminar approaches for microdiscectomy (MD) were included in the present review. Papers focused on endoscopic surgery for other spinal diseases were not included. From July 2009 to July 2015, we identified 51 surgical series, 5 systematic reviews, and one meta-analysis reported. In lumbar EDS, rate of complications, length of hospital staying, return to daily activities, and overall patients’ satisfaction seem comparable to standard MD. Rate of recurrence/residual seems higher in EDS, although data are nonhomogeneous among different series. Surgical indication and experience of the performing surgeon are crucial factors affecting the outcome. There is growing but still weak evidence that lumbar EDS is a valid and safe alternative to standard open microdiscectomy. Statistically reliable data obtained from randomized controlled trials (better if multicentric) are desirable to further confirm these results.
Endoscopic disc surgery (EDS) is a relatively well-known technique, which has been introduced since the ‘80s, but shows rapidly expanding interest in the last few years. The concept behind it is to provide a minimally invasive approach to the lumbar spine when treating disc herniations. Ideally, the goal of the developing endoscopic disc surgery is to get the same results obtained using standard microdiscectomy, providing effective treatment, targeted to the nerve decompression and not only focused on pain relief, like in nerve root/peridural injections, but at the same time avoiding discomfort related with open techniques.
Although fascinating, results of this technique are still debated, mostly due to (1) learning curve for surgeons not confident with the endoscopic kit in a spinal environment; (2) rate of recurrences of symptoms/radiological finding, which still seems to be higher compared to standard microdiscectomy; (3) lack of consistent evidence comparing outcomes of endoscopic and microscopic discectomy.
We performed an extensive review of the literature about EDS. The review is focused on introduction and development of the technique over time, results in terms of outcome, recurrence, and complications rate, available evidence reporting comparison between EDS and standard microdiscectomy, and possible future development.
First series of EDS are reported from the late ‘80s. Kambin and Schaffer reported initially successful experience in 88% of patients undergoing percutaneous discectomy [
Consequent diffusion of the technique led to extended series, reported in the mid ‘90s. With growing surgical experience, several authors started to raise and assess criticisms related with the far lateral percutaneous approach. The main problem concerned the lack of improvement in radicular symptoms, requiring reexploration surgery in 7 to 11% of cases [
As mentioned above, EDS has been broadly practiced, and many variations in name and techniques have been reported. Terminology is quite variable and, as always, different names indicating the same procedure with few variations are reported. However, to sum things up we might say that EDS mainly include two different approaches. The first one is the one we define here as the
It is not our intentions to describe the surgical technique in detail, since authoritative textbooks and papers already report it [
(a-b) Sagittal and axial T2-weighted MRI images of an L4-L5 right disc bulging causing foraminal stenosis. Approach is performed through an entry point located ~7 cm from the midline. (c-d) Intraoperative fluoroscopy and lateral and anteroposterior (AP) projections showing the position of the instrumentation. (e) Fragment of the disc removed from the endoscopic cannula.
(a-b) Preoperative T2-weighted sagittal and axial MRI showing an L5-S1 disc herniation impinging the left S1 nerve root. (c-d) Intraoperative fluoroscopy showing different phases of the transforaminal approach. AP view: pointer showing the L5-S1 interlaminar window and lateral view showing the radiofrequency bipolar endoscopic probe inside the L5-S1 intervertebral disc. (e) Removal of the herniated disc material has been completed. At the end of the procedure, the dural sac (ds), the S1 nerve root (s1) with its axilla (a), and shoulder (s) can be clearly visualized. Taken from the senior author’s personal series.
(a) Instrumentation: light source at the center of the surgical table, endoscopic cannula, and different pituitary forceps adapted for endoscopic use on the top of the picture. (b) Positioning of the endoscope during an interlaminar approach. (c) Positioning of the endoscope during a transforaminal approach, extreme lateral variation.
There is extensive literature about EDS and multiple surgical series are reported. Many reviews have also been published, although not systematic in most cases, and few clinical trials comparing EDS with standard microdiscectomy.
It was not the purpose of this paper to perform an extensive and omnicomprehensive literature review. For these reasons, with few exceptions, literature review is focused on the last six years. We reviewed all English-written papers about lumbar spine endoscopic microdiscectomy. Papers were collected using PubMed Database, and keywords for Medline were “endoscopic lumbar discectomy”. Literature reviews, case series, meta-analysis, randomized controlled trials, case-cohort studies, and prospective and retrospective series were all included. Small series (<10 cases) and case reports were excluded. Series focused on new techniques, disc recurrences, spinal instability, or different techniques were not considered, although some of them are mentioned in the Discussion.
Literature review was limited to English-written papers and only included the last 6 years of publications; thus it is not intended as systematic review or meta-analysis or as a comprehensive review about this topic.
From July 2009 to July 2015, we found 51 series about lumbar endoscopic discectomy reported in the international literature. Main results of each series are reported in Table
Series reported in the literature in the last 6 years. FED: full endoscopic discectomy; MED: microendoscopic discectomy; EDS: endoscopic discectomy; MD: microdiscectomy; TF: transforaminal; IL: interlaminar; OC: outcome; DVT: deep venous thrombosis.
First author | Year | Study | Number of pts. | Techn. | OC measures | Outcome | Recurrence rate/residual/redo |
Complications |
---|---|---|---|---|---|---|---|---|
Li [ |
2015 | EDS, comparison between FED and MED | 65 | TF and IL | VAS and ODI | No differences, shorter hospital staying in FED group | 8,6% FED; 6,7% MED | 1 dural tear |
Türk [ |
2015 | Surgical series EDS | 105 | TF | VAS and ODI | 90,4% pain relief | 2 redo surgeries | Not mentioned |
Wang [ |
2015 | Surgical series EDS | 207 | TF | VAS, ODI, and MacNab | 71–86% excellent OC, age related | 3 to 5% age-related | 3 dural tears, 1 postop instability |
Li [ |
2015 | Surgical series EDS | 72 | IL | VAS, ODI, and MacNab | 97% good to excellent OC | 1 | No complications noted |
Sairyo [ |
2014 | Surgical series EDS, analysis of complications | 100 | TF and IL | — | — | — | 2% nerve injury; 1% postop hematoma |
Liao [ |
2014 | Surgical series EDS | 15 | TF | VAS and MacNab | 93% good to excellent OC | — | — |
Sencer [ |
2014 | Surgical series EDS | 163 | TF and IL | VAS and ODI | 88% good to excellent OC | 8 (5%) | 6 (3%) dural tears; 5 (2,9%) types of postop worsening |
Yoshimoto [ |
2014 | Surgical series EDS, comparison between far lateral and intraforaminal disc herniations removal | 25 (far lateral) + 93 (IL) | TF | VAS and JOA | No significant differences in pain relief between the two groups | — | — |
Jasper [ |
2014 | Surgical series EDS, comparison between transforaminal and interlaminar approaches | 41 | TF and IL | VAS and MacNab | 75% pain relief in both groups | — | No complications noted |
Xu [ |
2014 | Surgical series EDS, analysis of learning curve | 36 | IL | VAS | Excellent outcome | 2 pts. converted to open surgery | No complications noted |
Hussein [ |
2014 | Comparison between EDS and MD | 185 | IL | NRS, MacNab, and ODI | Statistically significant pain relief in both groups | 2; 8 converted to open surgery | 3 dural tears |
Kulkarni [ |
2014 | Surgical series EDS | 188 | IL | VAS and ODI | Statistically significant pain relief | 3 (1,5%) | 11 (5%) dural tears, 1 (0,5%) infection, and 1 (0,5%) wrong level |
Choi [ |
2013 | Surgical series EDS, comparison between transforaminal and interlaminar approaches | 30 | TF and IL | VAS and ODI | Shorter recovery time in interlaminar | 3,3% TF; 6,7% IL | 6,7% postop dysesthesia |
Wang [ |
2013 | Surgical series EDS, comparison between early and delayed surgery | 145 | — | VAS and MacNab | No significant differences in pain relief between the two groups | 8 to 11% redo | No complications noted |
Kim [ |
2013 | Surgical series EDS, comparison between interlaminar approach alone and interlaminar + annular sealing | 224 | IL | VAS and ODI | Statistically significant pain relief in both groups | 5% IL + sealing; 13% IL alone | — |
Yoshimoto [ |
2013 | Surgical series EDS | 25 | — | JOA | 80,4% of pain improvement | 0 | No complications noted |
Jasper [ |
2013 | Surgical series EDS | 195 | TF | VAS | 83,9% improvement in single level pathology; 69,7% improvement in multilevel | — | — |
Wang [ |
2013 | Surgical series EDS, analysis of learning curve (comparison between 2 groups operated on by surgeons with different level of training) | 120 | TF | VAS and JOA | Significant improvements in both groups | 20 residuals, 14 (23%) group A; 6 (10%) group B; 2 recurrences | 2 postop infections |
Choi [ |
2013 | Surgical series EDS, intraop magnetic imaging | 89 | TF | VAS, ODI, and MacNab | Significant improvement | 4 (4,5%) residuals; 2 (2%) recurrences | 2 postop hematomas |
Jasper [ |
2013 | Surgical series EDS | 50 | TF | VAS | 71 to 75% pain relief | 10% | No complications |
Yadav [ |
2013 | Surgical series EDS | 400 | IL | VAS and MacNab | 90% significant improvement | 2 (0,5%) | 3 facet injuries; 7 dural tears; 2 infections; 1 persistent paresthesias |
Soliman [ |
2013 | Surgical series EDS | 41 | IL | VAS and ODI | 95% excellent to good improvement | 1 | 2 dural tears |
Matsumoto [ |
2013 | Surgical series EDS, analysis of recurrences | 344 | — | JOA | 75 to 83% recovery rate | 37 (10,8%) | — |
Hsu [ |
2013 | Comparison between EDS and MD | 59 | TF and IL | VAS and ODI | No significant differences between EDS and standard microdiscectomy groups | 2 recurrences, 4 persistent symptoms | 2 nerve root injuries |
Chaichankul [ |
2012 | Surgical series EDS, analysis of learning curve | 50 | TF | VAS | Significant improvement in both groups, higher in later stages of learning curve | — | — |
Kim [ |
2012 | Surgical series EDS for migrated discs | 18 | IL | MacNab | 89% of complete removal | 2 residuals | 1 dural tear |
Hirano [ |
2012 | Surgical series EDS | 37 | TF and IL | VAS and JOA | Significant improvement | 2 | — |
Yoon [ |
2012 | Surgical series, comparison of EDS and tubular-retractor microdiscectomy | 37 EDS + 35 MD | TF | VAS, ODI, and SF-36 | No significant differences between EDS and standard microdiscectomy groups | 1 in each group | 1 dural tear; 1 bowel perforation |
Wang [ |
2012 | Surgical series EDS | 151 | — | MacNab | 91% good to excellent OC | 5 (3,5%) | 5 pts. (3,5%) dural tears; 3 pts. (2,1%) discitis |
Lübbers [ |
2012 | Surgical series EDS | 22 | TF and IL | VAS, ODI, and MacNab | 18 pts. (81%) good OC | 2 (9,1%) | 1 stroke |
Han [ |
2012 | Surgical series EDS, analysis of technique | 41 | TF | MacNab | 39 pts. excellent to good OC | — | 2 nerve root injuries |
Kaushal [ |
2012 | Surgical series EDS | 300 | IL | MacNab | 90% excellent to good OC | — | 6 discitis cases; 5 dural tears; 2 nerve root injuries |
Kim [ |
2012 | Surgical series EDS, analysis of technique | 30 | IL | — | Significant improvement | — | No complications noted |
Tenenbaum [ |
2011 | Surgical series EDS, analysis of technique, complications, and learning curve | 124 | TF | VAS and ODI | OC comparable to open surgery | 20,9% redo surgery | 1,6% complication rate |
Chumnanvej [ |
2011 | Surgical series EDS | 60 | IL | MacNab | 91,6% excellent outcome | 2 | No complications |
Cho [ |
2011 | Surgical series EDS, analysis of complications | 154 | TF | VAS and ODI | Significant improvement | 3 (1,95%) | 1 dural tear; 1 discitis |
Choi [ |
2011 | Surgical series EDS, focused on annuloplasty and LBP improvement | 52 | TF | VAS and ODI | 78,4% improvement | 18 residuals; 2 recurrences | No complications noted |
Chen [ |
2011 | Surgical series EDS, focused on anesthesia | 123 | IL | VAS and ODI | Significant improvements in both groups | 3 | 1 dural tear |
Dezawa [ |
2011 | Surgical series EDS, focused on technique | 30 | IL | — | Significant improvement | 1 persistent radiculopathy | — |
Garg [ |
2011 | Comparison between EDS and MD | 112 | TF | ODI | Statistically significant pain relief in both groups | 1 | EDS, 5 dural tears |
Doi [ |
2011 | Surgical series EDS | 17 | TF and IL | JOA | 16 pts. significant improvement | 3 | No complications noted |
Casal-Moro [ |
2011 | Surgical series EDS | 120 | TF and IL | VAS and ODI | 92% good to excellent OC | 7,5% redo surgery | 4,1% dural tear; 4 nerve root injuries; 1 DVT; 1 discitis |
Wang [ |
2011 | Surgical series EDS, analysis of learning curve | 30 | IL | VAS | Significant improvement | 20% converted to open | 12 to 10%, depending on the group |
Lee et al. [ |
2010 | Surgical series EDS | 25 | TF | VAS and ODI | Significant improvement | 1 residual; 1 recurrence | No complications noted |
Ahn [ |
2010 | Surgical series EDS, focused on annuloplasty and LBP improvement | 87 | TF | VAS, ODI, and MacNab | 72% good to excellent OC | 13 converted to open | No complications noted |
Jhala and Mistry [ |
2010 | Surgical series EDS | 100 | IL | MacNab | 91% good to excellent OC | 4 | 4 discitis cases; 1 nerve root damage |
Teli [ |
2010 | Comparison between EDS and MD, focused on complications | 224 | — | VAS, ODI, and SF-36 | Higher rate of complications in EDS group | 8 | 6 dural tears; 2 nerve injuries; 1 discitis |
Peng [ |
2010 | Surgical series EDS | 55 | — | VAS, NASS, and SF-36 | Significant improvement | 5% | — |
Lee [ |
2009 | Comparison between EDS and MD | 54—25 EDS, 29 MD | TF | VAS and ODI | Significant improvement in both groups, but reduction in hospital staying and recurrence rate in EDS group | 1 EDS persistent pain; 4% | 1 unspecified complication |
Chae [ |
2009 | Surgical series EDS, analysis of technique | 153 | TF | VAS and MacNab | 94% excellent to good OC | Not reported | 1 paravertebral hematoma; 3 transient pareses; 8 transient hypoesthesia cases |
Zhou [ |
2009 | Surgical series EDS | 275 | TF | MacNab | 91% good to excellent OC | 5 | 5 dural tears; 3 infections |
Out of this group, 21 articles reported results of surgical series, 5 papers were focused on analysis of surgical technique and its variations, 4 were comparison between endoscopic discectomy and standard microdiscectomy, 5 were focused on complications, and the rest were focused on different topics (learning curve, use of annuloplasty, etc.), Table
Number of patients enrolled varied from 15 [
Surgical technique was not always specified, but larger series of patients treated through interlaminar approach were growing through the years. Specifically, both Yadav and Kaushal reported 400 and 300 patients treated through interlaminar approach, respectively [
Outcomes reported are quite homogeneous among most series. Virtually all authors report a good to excellent outcome in 70 to 90% of patients treated, according to MacNab criteria. Rate of recurrence/residual is by far one of the most debated topics in literature. Interestingly, most series reported a rate of recurrence similar to standard microdiscectomy (2 to 10%). However, results are extremely variable from this point of view. One of the largest series [
The overall opinion reported in discussion/conclusions sections of most authors is that results of endoscopic microdiscectomy are comparable to the one of standard microdiscectomy. Out of this group, two series report considerations worth mentioning. The first is the one from Teli and colleagues, who reported a higher rate of complications in patients treated with endoscopic discectomy (224 patients, randomized in 3 groups) [
In early 2015, Dohrmann and Mansour published one of the largest reviews analysing results of different surgical techniques for lumbar disc herniations. Outcomes of multiple studies were reviewed and compared. Good to excellent outcome is reported in 80% of patients undergoing endoscopic discectomy. These results were similar to the standard microdiscectomy (70 to 84%) [
The main problem with the data analysis is the lack of systematic reviews, this being also related to lack of randomized control trials comparing standard microdiscectomy/open discectomy with endoscopic lumbar discectomy.
In the last 6 years of medical literature, we found 6 reviews overall, including the one from Dohrmann et al., 2 of them being Cochrane reviews [
Smith and colleagues reported a detailed selection of studies over a 6-year period, in order to identify randomized control trials comparing endoscopic discectomy with microdiscectomy [Smith]. Out of 109 studies analysed, the authors found only 4 randomized controlled trials meeting the eligibility criteria [
Another interesting review is the one reported by Birkenmaier and colleagues [
Two Cochrane reviews were also reported [
All the previously mentioned reviews reported that more randomized control trials are needed in order to get stronger evidence about endoscopic lumbar discectomy.
Finally, one meta-analysis was reported so far in the international literature [
This review has serious limitations and, as specified before, it should not be intended as a systematic or comprehensive review of all studies reported in the literature. Our goal was only to provide an update about this topic, focusing on the main debated issues (recurrence/complications rate) and on possible future developments.
What we know today is that the number of centres and surgeons practicing EDS is exponentially increasing. Despite its basics being described since the early ‘90s, in the last ten years we have assisted at a wide diffusion and rapidly growing spreading of this technique. As mentioned previously, 51 surgical series have been reported in the English literature, and far more were found in other languages. Moreover, we focused our attention only on transforaminal and interlaminar endoscopic discectomy, also excluding recurrence series and series focused on a specific aspect.
One of the largest series of EDS reported has been published in 2015 and includes 10228 patients treated through a transforaminal approach [
Proper choice of indication is of paramount importance for the outcome. In authors’ experience and on the basis of the literature data, endoscopic techniques should be used in patients showing fresh or relatively fresh fragments, even migrated, with minor or no signs of diffuse spinal degenerative disease, such as broad disc bulge, spinal stenosis secondary to hypertrophic ligament/osteophytes, and spinal instability. Moreover, use of the endoscope in spinal procedures may be challenging for surgeons not used to the endoscopic kit and techniques, and it requires dedicated training and learning curve. Two series recently reported highlighted the different results obtained from surgeons with different level of experience in EDS. Specifically, both articles reported higher rate of recurrence/residual in patients operated on by surgeons at the earlier stage of their learning curve [
However, the lack of randomized controlled trial keeps us cautious about the interpretation of these results. Ideally, a multicentred, randomized control trial enrolling large number of patients and surgeons with similar degree of experience should clarify whether results of EDS are comparable or superior to the ones of standard microdiscectomy.
Despite the lack of defined clinical evidence, lumbar EDS is undoubtedly a rapidly expanding field and it is not unreasonable to look at its future developments as incredibly promising. Even if not mentioned here, indications for endoscopic techniques are gradually extending to other lumbar diseases, such as instability [
Basing on the data available so far about lumbar EDS, few points are highlighted. There is growing but still not sufficient evidence that lumbar EDS shows slightly better results in terms of minor tissue damage, shorter hospital staying, quicker return to normal daily activities, and patient satisfaction. Rate of recurrence/residual is still a matter of debate, and it seems to be strictly related to appropriate surgical indications and level of training of the operating surgeon. Rate of complications seems similar in both open and endoscopic techniques; however results reported are extremely nonhomogeneous in different series. More randomized controlled trials, systematic reviews and meta-analysis are needed to clarify whether lumbar EDS can be considered comparable if not superior to standard open discectomy or not.
There is no conflict of interests of any author in relation to the submission.