Comparison of outcomes in open and full endoscopic lumbar discectomies for treating lumbar radiculopathy in an Australian cohort
Highlight box
Key findings
• Endoscopic spine surgery (ESS) is non-inferior to open approaches for treatment of lumbar radiculopathy in an Australian cohort. Length of stay was shorter in the ESS cohort.
What is known and what is new?
• ESS is known internationally as an alternative to open approaches to treat lumbar disc herniations, with good outcomes, however given its recent emergence in Australia, there is minimal data on outcomes in a local cohort.
• The manuscript adds the first dual surgeon prospective comparison of endoscopic and open approaches to treat lumbar radiculopathy in an Australian cohort, given the paucity in Australian data for this emerging technology.
What is the implication, and what should change now?
• The implication of this study is that endoscopic spine surgery offers an alternative to open approaches, and offers some advantages including shorter length of admission.
• This study adds further weight on the need to expand endoscopic spine surgery in Australia to assess its impact on patient outcomes in the treatment of lumbar radiculopathy in the local population, given its widespread adoption internationally.
Introduction
Surgical approaches to address lumbar radiculopathy have been evolving over the past century, allowing approaches with less tissue trauma and hence better recovery post operatively. The mainstay of treatment can be separated into open (either through microscopic or loupe magnification, with the use of tubular or open retractors) and endoscopic approaches, with the use of spinal endoscopes.
Since the 1970s, when Kambin introduced the Craig Cannula to perform a percutaneous lumbar discectomy, surgeons have explored percutaneous approaches to lumbar discectomies (1). Two decades later, the first percutaneous endoscopic lumbar discectomy was performed by Mayer and Brock (2) with the use of an angled endoscope, allowing the progression of technology to the modern scopes used today.
Despite the international data and its availability for almost three decades, adoption of endoscopic approaches to spine surgery has been slow in Australia. Availability in Australia is predominantly in the private sector due to limitations in equipment availability. Given the technology’s relatively recent emergence, there are few studies comparing endoscopic and open approaches. At present there is very limited Australian data on the outcomes of patient having endoscopic spine surgery (3).
We present the first prospective, dual-surgeon comparison of ESS and open approaches to treat lumbar radiculopathy in an Australian cohort. We aim to find if ESS is non-inferior to open approaches for the treatment of lumbar radiculopathy in post operative outcomes of pain and disability scores, to address the paucity in outcome data for ESS in Australian patients. We present this article in accordance with the STROBE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-24-116/rc).
Methods
Routinely collected prospective data (pre and post operative Visual Analogue and Oswestry Disability Scores) were collated from consecutive patients who had single level uniportal endoscopic discectomies for radiculopathy caused by lumbar disc herniation by two surgeons (authors Y.L. and S.G.) at Norwest Private Hospital between December 2020 and October 2022. These were compared to data from consecutive patients who underwent open approach by microsurgical discectomies from August 2020 to September 2022 by the same surgeons at other private hospitals (The Sydney Adventist Hospital and Westmead Private Hospital) where the endoscope was unavailable, otherwise deemed suitable for either approach by the operating surgeons.
The patients (both from open “conventional” microdiscectomies and endoscopic discectomies) allowed direct comparison of consecutive patients operated on for comparable pathologies, differentiated only by equipment availability.
Six-week and six-month outcomes were compared in both ESS and open cases. Data analysed included pre- and post-operative Visual Analog Scale (VAS) for back and leg pain (VAS-B and VAS-L), Oswestry Disability Index (ODI), Complication rates and length of stay (LOS). The non-inferiority margin for ESS was set at an inferiority of 0.5 for VAS and 10 for ODI based on established literature (4,5).
Statistical analysis
Baseline characteristics and outcomes of the study cohort were summarised with descriptive statistics. Continuous variables were described with medians and interquartile ranges due to non-normal distributions. Categorical variables were described with counts and percentages. The independent T-test and Chi-square test were used to analyse differences between endoscopic and open microscopic approaches on continuous and categorical outcomes respectively. Between group mean differences were calculated with 95% confidence intervals. Non-inferiority analyses were performed on patient reported outcomes at 6 weeks and 6 months. Complication rate was compared in aggregate with the Chi-square test. A two-tailed alpha of 0.05 was set as the threshold for statistical significance. All analyses were conducted using R version 4.3.0.
Ethical consideration
The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). It was deemed to be of negligible risk according to the National Statement on Ethical Conduct in Human Research and granted an exemption by Ramsay Health Care Human Research Ethics Committee in accordance with the NHMRC National Statement with individual consents waived.
Results
There were a total of 189 cases analysed. Baseline characteristics of the cohort are outlined in Table 1. This included 92 endoscopic and 97 open cases. Of the endoscopic cases, 38 were interlaminar (Figure 1) and 54 transforaminal (Figure 2). Details of the cases, including which lumbar segments were involved, are presented in Table 2. Of the interlaminar decompressions, 30 were at L5/S1. There was a modest difference between baseline VAS-B scores between the two cohorts. VAS-L and ODI values were similar. Patient reported outcomes are outlined in Table 3, and presented against baseline scores in Figure 3.
Table 1
| Characteristics | Open (n=97) | Endoscopic (n=92) | Between group difference (95% CI) | P value |
|---|---|---|---|---|
| Age (years) | 48.0 (39.0 to 63.0) | 44.5 (36.0 to 58.0) | −3.6 (−8.0 to 0.8) | 0.11 |
| Male sex | 57 [59] | 59 [64] | 5% (−10% to 20%) | 0.54 |
| Pre-operative VAS back pain | 7.0 (4.0 to 8.0) | 5.0 (3.0 to 7.3) | −1.3 (−2.0 to −0.5) | 0.002 |
| Pre-operative VAS leg pain | 8.0 (7.0 to 9.0) | 8.0 (7.0 to 9.0) | 0.3 (−0.1 to 0.7) | 0.17 |
| Pre-operative ODI | 60.0 (50.0 to 66.0) | 58.0 (48.8 to 64.0) | −0.2 (−4.3 to 3.8) | 0.90 |
Data are presented as median (IQR) or n [%]. CI, confidence interval; VAS, Visual Analogue Scale; ODI, Oswestry Disability Index; IQR, interquartile range.
Table 2
| Characteristics | Open (n=97) | Endoscopic (n=92) | Total (n=189) |
|---|---|---|---|
| Level | |||
| L2/3 | 3 | 2 | 5 |
| L3/4 | 12 | 10 | 22 |
| L4/5 | 48 | 44 | 92 |
| L5/S1 | 34 | 36 | 70 |
| Location | |||
| Central | 12 | 4 | 16 |
| Paracentral | 77 | 79 | 156 |
| Foraminal/extraforaminal | 8 | 9 | 17 |
| Approach (endoscopic) | |||
| Interlaminar | – | 38 | 38 |
| Transforaminal | – | 54 | 54 |
Table 3
| Outcomes | Open (n=97) | Endoscopic (n=92) | Between group difference (95% CI) | P value |
|---|---|---|---|---|
| VAS back pain | ||||
| 6 weeks | 1.0 (0.0 to 2.0) | 1.0 (0.0 to 2.0) | −0.3 (−0.8 to 0.2) | 0.002* |
| 6 months | 2.0 (0.0 to 3.0) | 2.0 (0.0 to 3.0) | 0.0 (−0.6 to 0.6) | 0.09* |
| VAS leg pain | ||||
| 6 weeks | 1.8 (0.0 to 2.0) | 1.0 (0.0 to 2.0) | −0.5 (−1.1 to 0.0) | <0.001* |
| 6 months | 1.0 (0.0 to 2.5) | 1.0 (0.0 to 2.9) | −0.2 (−0.8 to 0.5) | 0.057* |
| ODI | ||||
| 6 weeks | 20.0 (13.0 to 23.0) | 18.0 (13.0 to 22.3) | −0.5 (−4.0 to 3.1) | <0.001* |
| 6 months | 20.0 (7.0 to 20.0) | 14.0 (7.0 to 28.5) | −1.6 (−6.8 to 3.7) | <0.001* |
| Length of stay ≤1 day | 74 [78] | 86 [93] | 16% (5% to 26%) | 0.005 |
| Reoperation | 7 [7] | 9 [10] | 2% (−7% to 12%) | 0.73 |
Data are presented as median (IQR) or n [%]. *, non-inferiority analyses with margin of non-inferiority of 0.5 for VAS and 10 for ODI. CI, confidence interval; VAS, Visual Analogue Scale; ODI, Oswestry Disability Index; IQR, interquartile range.
ESS cases were statistically non inferior to open cases in all patient reported outcomes at 6 weeks. Negative between group differences for VAS-B (−0.3), VAS-L (−0.5) and ODI (−0.5) indicated lower scores in the ESS group compared to the open group. At 6 months, only ODI was statistically non-inferior with a between group difference of −1.6. Comparisons of VAS-B (0.0) and VAS-L (−0.2) also suggested non inferiority of the ESS group, but these did not achieve statistical significance.
LOS data showed more patients were discharged within 24 h in the ESS cohort compared with the open cohort (93% vs. 78%, P=0.005). Complication rates were lower in ESS (5% vs. 6%, P>0.99) however this was not statistically significant. See Table 4 for summary of complications.
Table 4
| Complications | Open (n=97) | Endoscopic (n=92) | Total |
|---|---|---|---|
| Durotomy | 4 | 0 | 4 |
| Neurological deficit | 0 | 2 | 2 |
| DRG irritation | 1 | 2 | 3 |
| Infection | 0 | 1 | 1 |
| Haematoma | 1 | 0 | 1 |
| Total | 6 [6] | 5 [5] | 11 |
Data are presented as n or n [%]. DRG, dorsal root ganglion.
The endoscopic cohort had no durotomies, with 4 in the open cohort, possibly accounted for by the constant irrigation pressure pushing dura away from the scope during ESS. There was one case of persistent exiting nerve motor weakness following transforaminal endoscopic lumbar decompression which gradually improved over time with physiotherapy. There was 1 case of worsening traversing nerve numbness following interlaminar endoscopic decompression, likely secondary to retraction. The ESS cohort had one infection, which was a superficial wound infection in an obese, immunosuppressed elderly male following transforaminal endoscopic lumbar decompression which resolved with oral antibiotics. Two patients in the ESS cohort, and one patient in the open cohort, experienced irritation of the dorsal root ganglion (DRG). Two endoscopic cases had to be converted to an open operation. Both of these were in patients with hard calcified discs, a factor we have identified as predictive of poor outcome during the initial learning curve (6). Reoperation rates were similar (10% in the endoscopic cohort vs. 7% in the open, P=0.73) for symptomatic recurrence of the disc herniation.
Discussion
Following the first documented percutaneous endoscopic discectomy in 1993, endoscopic spine surgery has gained increased popularity worldwide. Multiple international studies have shown the effectiveness of the endoscopic spine surgery (ESS) in addressing lumbar disc herniations (LDH) causing pain, with a reduction in VAS scores of back pain (7), reduced inflammatory markers [C-reactive protein (CRP), creatine phosphokinase (CPK) and interleukin-6 (IL-6)] (8), improvements in ODI scores and hospital LOS when compared with the open approach (9).
Results obtained in our study are in keeping with that from similar studies internationally. Similarly to our results, Gadjradj showed percutaneous endoscopic discectomy was non-inferior to open microdiscectomy in reduction of leg pain (4). Ruetten et al. carried out a prospective randomised control trial of patients with LDH operated in either full endoscopic or microsurgical techniques (10). Later, in 2017 Gibson carried out a similar study comparing transforaminal endoscopic discectomies to the traditional microsurgical approach (9). Both these studies found the endoscopic approach to be as good as microdiscectomies when reviewing pain scores and post-operative outcomes. A meta-analysis of 7 papers examining 1,254 patients by Kim et al. compared percutaneous lumbar discectomy with open microdiscectomy in the Korean population. They found a reduction in the VAS, ODI, operation time and hospital stay in endoscopic spine surgery compared with open microdiscectomy, with no change in complication or recurrence rates (11).
Despite this, ESS’s uptake in Australia has been slow with only a handful of private centres in Australia performing endoscopic spine surgeries. Reidy et al. found one barrier being the perceived time taken to master the technique and the lack of training opportunities (12), along with lack of compelling evidence in the medical literature. Our results, showing non-inferiority in 6 weeks in all primary outcomes, as well as at 6 months in ODI, will hopefully give local surgeons the confidence in the ESS approach to potentially apply it to their day-to-day practice.
Although the current endoscopic cohort represent the first ESS cases performed by the two surgeons, our results demonstrate the safety and efficacy of the approach even during the initial learning curve. All patients in our study who had endoscopic microdiscectomies were included in the analysis. The learning curve in endoscopic spine surgery has been reported as little as 15 patients (13). Furthermore, a recent study showed that although there was an increase in the time taken in the initial learning curve, there were no statistically significant differences in complications, conversion to open and recurrences. They also found that patients in both the learning curve period and the time thereafter all experienced a statistically significant reduction in postoperative VAS and ODI compared to pre-operative scores (14).
Over the 3-year period from 2015–2018, there were 43,185 hospitalisations for lumbar spinal decompressions (excluding spinal fusions) in Australia, with 82% of these being for privately funded patients (15). Recent estimates for costs for a hospital bed per day ranges from $1,075 to $2,370 per day between states in Australia (16,17) in the public sector alone. Golan et al. conducted a systematic review in 2023 showing that while ESS had higher operating costs when compared to open microsurgical approaches, studies that measured healthcare and societal costs found endoscopy to be advantageous (18). Gadjradj et al. conducted a cost-effectiveness analysis alongside their non-inferiority study, and found that similarly, surgical costs were higher for endoscopic than for open microdiscectomies, but all other disaggregate costs as well as total societal costs being lower for endoscopic surgery. They suggested that endoscopic spine surgery was more cost-effective from a societal perspective compared to open microdiscectomy (19). With the growing need to address strain on the healthcare system, a reduction in hospital LOS by one day could save thousands of dollars in healthcare costs, and the use of ESS for lumbar microdiscectomies may help some of these pressures with the reduction in LOS. LOS was lower in the ESS compared with open cohort in our analysis. Lower tissue injury and significantly reduced inflammatory response (8) are factors attributed to faster recovery times and shorter hospital LOS.
Patients undergoing ESS can experience DRG irritation. Rates of DRG irritation of up to 21% have been quoted in multi-centre studies (20), mostly in patients having transforaminal approaches where the endoscope is docked at the foramen near the DRG. This often improves with supportive measures, but may need analgesia or epidural steroid injections in the immediate post-operative phase in some patients. Two patients in the ESS cohort experienced DRG irritation. One patient in the open cohort experienced DRG, although these were likely under-reported given the interval to first postoperative follow-up was 6 weeks.
There were no durotomies in our endoscopic cohort. Given constant irrigation and working in a fluid environment however, it is important to identify durotomies either intraoperatively, or have a high index of suspicion for incidental durotomies. Care should be taken in monitoring patients post operatively for sequelae of dural tears, including headaches, nausea, vomiting, neurological deficits and haemodynamic instability (especially in the immediate post-operative period) (21), as they may require reoperation (open or endoscopic) if initial conservative measures fail.
Limitations
Our study is the first of its kind prospectively assessing the outcomes of ESS and open microdiscectomies in an Australian cohort performed by more than one surgeon. However, given that ESS was only available at a single private hospital, one limitation of our study was that randomisation was not feasible. Another limitation was the small sample size as, given the emergence of new technology in select Australian facilities, endoscopic spine surgery was not available all hospitals. Given the small sample size, and the fact that endoscopic spine surgery was only available at a single private hospital, randomization was not possible. Future studies on Australian cohorts could be carried out when ESS becomes more widely available in both private and public hospitals, allowing recruitment, and potentially randomisation, of more patients.
Furthermore, the fact that only patients from private hospitals were included is identified as a potential source of bias given the difference in socioeconomic factors as well as health literacy between patients who have access to private healthcare and those without (22). The authors identify this as a source of potential selection bias, as it may not be translatable to the Australian population as a whole. However, the aim of this study was to assess if the endoscopic spine surgery technique was non-inferior to open surgery and in order to minimise the risk of bias, we compared patients only in the private sector. Future randomised longer-term studies involving multiple institutions and larger cohorts are required in order to improve generalizability of our results and truly compare not just clinical outcomes but also potential public health implications ESS may have in alleviating strains on the Australian healthcare system.
Conclusions
ESS is a non-inferior option to open discectomy for patients with lumbar radiculopathy when looking at six-week outcomes of ODI, VAS-L and VAS-B, and at 6 months for ODI. Despite not achieving statistical significance, the six-month data for VAS-L and VAS-B also did not show ESS being any worse, and the potential benefits including shorter hospital LOS, complications and tissue disruption can be beneficial from both a patient and organizational perspective in treating patients with lumbar radiculopathy.
Acknowledgments
None.
Footnote
Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-24-116/rc
Data Sharing Statement: Available at https://jss.amegroups.com/article/view/10.21037/jss-24-116/dss
Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-24-116/prf
Funding: None.
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-24-116/coif). The authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). It was deemed to be of negligible risk according to the National Statement on Ethical Conduct in Human Research and granted an exemption by Ramsay Health Care Human Research Ethics Committee in accordance with the NHMRC National Statement with individual consents waived.
Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.
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