Introduction
Degenerative disc disease is one of the most prevalent causes of lower back pain, affecting roughly 266 million people worldwide annually [1]. Among the many pathologies classified under degenerative disc disease, lumbar disc herniation is often the most common pathology, with one study showing that it accounted for up to 55.1% in a population of 8,161 patients [2]. Literature has shown that 95% of lumbar disc herniations occur within the L4–L5 or L5–S1 segments and are initially treated using nonoperative measures, including physical therapy, nonsteroidal anti-inflammatory drugs, electrotherapy, and epidural steroid injections [3–5]. However, as symptoms become resistant to treatment, surgical intervention is often performed, which involves various forms of discectomies, microdiscectomies, laminectomies, and artificial disc replacement [6,7]. Although open lumbar discectomy had traditionally been the mainstay of surgery, the development of endoscopic techniques has shifted the surgical landscape toward a minimally invasive approach. Such an approach has consistently demonstrated significant advantages relative to open procedures, including smaller incisions, reduced surgical site infections, fewer dural tears, shorter postoperative length of stay, reduced return to work time, and lower Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) scores at the final follow-up [8–10].
Despite the proven benefits of lumbar endoscopic discectomy techniques, the current literature has shown no significant decrease in the rates of reherniation or reoperation [8–11]. This finding can be primarily attributed to the annulus fibrosus, a critical structural component that prevents the herniation of the nucleus pulposus and provides mechanical stability through compressive and shear weight bearing [12,13]. The nature of discectomies, regardless of technique, involves either a preexisting or operative incision of the annulus fibrosus for the removal of the nucleus pulposus, effectively eliminating these benefits with increases in rotational and disc stress [14,15]. To address this concern, various techniques and materials have been developed, with special emphasis on suturing and biomaterial scaffolding architectures [16–18].
Although individual studies have reported on the use and outcomes of additional annulus fibrosus repair, to our knowledge, this systematic review has been the first to compare endoscopic lumbar discectomy with and without annulus fibrosus repair. Owing to the heterogeneity of the results presented in the current literature, the primary objective of this study was to evaluate the clinical viability and safety of endoscopic lumbar discectomy with annulus fibrosus repair, focusing primarily on measuring reherniation and reoperation rates. Our secondary objectives included determining whether this procedure had clinically impactful results on operative time, blood loss, postoperative length of stay, and patient-reported outcomes (VAS/ODI). By synthesizing currently available evidence on this technique, our review seeks to provide clinicians with evidence that could effectively guide their patients through surgical planning and outcome expectations when considering lumbar endoscopic discectomy with annulus fibrosus suturing for herniated disc repair.
Materials and Methods
Ethics statement
Given the nature of this systematic review, no additional institutional review board approval was necessary. Moreover, no patient consent was needed as all data were collected from other sources with deidentified patient data.
Study design
This systematic review was presented following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and used studies published in the online PubMed, Embase, and Cochrane Library databases from the start of this project on June 8, 2025 to the present [19]. This review aimed to identify articles relevant to the assessment of endoscopic lumbar discectomy with and without annulus fibrosus suturing. The PRISMA flowchart is shown in Fig. 1.
Search strategy
A comprehensive literature search was performed using the Boolean method with search terms including “endscopic,” “lumbar,” “lumbar herniation,” “biportal,” “uniportal,” “discectomy,” “percutaneous,” “annulus fibrosus,” “annulus fibrosus suture,” and “annulus fibrosus repair.”
Inclusion and exclusion criteria
The inclusion criteria for this systematic review were as follows: (1) studies involving patients who underwent endoscopic lumbar discectomy with annulus fibrosus suturing; (2) those that directly compared to patients who did and did not have annulus fibrosus suturing; (3) those that recorded surgical outcomes, including operative length, blood loss, hospital length of stay, and complications; (4) those that recorded patient-reported outcomes, including VAS and ODI; (5) those that were full-length texts published in English; and (6) those with a patient population >18 years of age. The exclusion criteria were as follows: (1) studies not published in English or those whose full-length texts were inaccessible, (2) those including <10 patients and had a follow-up duration of under 12 months, (3) those involving pediatric patients or lacked recorded outcomes, and (4) those not relevant to the topic.
Literature selection
Two independent researchers (R.L. and J.C.) evaluated the study abstracts and titles based on this study’s inclusion/exclusion criteria using three databases. Any misunderstandings and disagreements regarding article inclusion were resolved by a third author (K.M.). Manual searches through bibliographies, references, and citations of included studies were conducted to identify all possible relevant articles overlooked by our electronic database searches. Fig. 1 shows the PRISMA flowchart detailing this search strategy.
From our final list of studies, data relevant to our primary outcome, including herniation rate and patient-reported outcomes (e.g., VAS/ODI) were collected. Data relevant to our secondary outcomes, including loss of intervertebral disc height, operative length, blood loss, and hospital length of stay, were additionally recorded.
Meta-analysis
Direct meta-analysis was performed for all recorded variables with sufficient data for comparing both groups, which included operative length, hospital length of stay, rate of herniation, and patient-reported outcomes (VAS/ODI). Discrete variables were presented as odds ratios (ORs) with 95% CIs, whereas continuous variables were presented as weighted mean differences (WMDs) with 95% CIs. For continuous variables reported in this study as the change from preoperative to postoperative values, namely, VAS and ODI scores, neither correlation coefficient nor standard deviations of the change were recorded. To account for this, sensitivity tests were performed using correlation coefficient values of r=0.3, 0.5, and 0.7 [20]. Additionally, all meta-analyses were conducted entirely using random-effects models to account for the variability between studies. All statistical analyses were performed using STATA ver. 18.0 BE-Basic Edition (Stata Corp., College Station, TX, USA), with a p-value of 0.05 indicating statistical significance.
Quality and publication bias assessment
Quality assessment of the included studies was performed using the NewCastle-Ottawa Assessment Scale shown in Appendix 1. Publication bias was assessed through funnel plots to observe for any obvious asymmetry, as seen in Appendices 2–6. Egger’s regression intercept test was also performed to determine the significance of the publication bias.
Results
Study demographics
Our final search initially yielded 452 studies. Among these studies, 158 were deemed duplicates and excluded. Another 274 studies were excluded for not meeting the inclusion criteria, and seven were removed for lack of relevance or missing data. Ultimately, nine studies were included for analysis. Fig. 1 depicts the entire PRISMA search strategy.
This systematic review included a total of 1,192 patients who underwent endoscopic lumbar discectomy for lumbar herniation. Among the included patients, 514 (43.1%) underwent additional annulus fibrosus repair via suturing, with 188 (36.5%) of these procedures utilizing an annulus fibrosus suture device, whereas 678 patients (56.9%) underwent initial discectomy alone (Table 1) [21–29]. The disc segment most commonly involved was L4/L5 with 267 patients (44.5%), followed by L5/S1 with 247 patients (41.2%), and lastly L3/L4 with 86 patients (14.3%) (Table 2).
Direct meta-analysis
Operative time
Operative time was recorded in all nine studies. Comparative analysis showed that endoscopic lumbar discectomy with additional annulus fibrosus suturing promoted a significant increase in operative time by 8.89 minutes (WMD, 8.89 minutes; 95% CI, 1.01–16.77; p=0.03). Fig. 2 provides a forest plot for a visual representation of this analysis [21–29]. Notably, Xi et al. [26] was the only study to have recorded a shorter operative length among those who underwent additional annulus fibrosus suturing (WMD, −15.74 minutes; 95% CI, −22.71 to −8.77; weight=10.67%). This variability and increase in surgical time can be attributed to the addition of a secondary procedure, as well as surgical skill.
Blood loss
Only five studies have recorded the amount of blood lost between both procedures. Meta-analysis results showed that although endoscopic lumbar discectomy with annulus fibrosus suturing increased operative blood loss by 2.04 mL, such an increase was not significant (WMD, 2.04 mL; 95% CI, −0.29 to 4.36; p=0.09). Fig. 3 presents a forest plot for this analysis [21,25,27–29]. Zhou et al. [21] was the only study to have recorded a higher blood loss in patients who underwent endoscopic lumbar discectomy alone, as well as those having an extremely high level of variability (WMD, −0.15 mL; 95% CI, −6.81 to 6.51; weight=8.71%). Similar to operative length, this finding can be possibly attributed to surgical skill.
Hospital length of stay
Postoperative length of stay was recorded in six studies but showed no significant difference between the groups. Our meta-analysis revealed a 0.71-day increase in length of stay among patients who underwent endoscopic lumbar discectomy with annulus fibrosus suturing (WMD, 0.71; 95% CI, −0.91 to 2.32; p=0.39). Although the majority of studies showed negligible differences in patients’ length of stay, Ren et al. [23]reported a significantly higher length of stay (by 4.8 days) among patients who received additional annulus fibrosus suturing (WMD, 4.80 days; 95% CI, 4.05–5.55; weight=16.68). This finding can be potentially attributed to multiple factors, including poor suture placement, surgical wound infection, or even poor patient management (Fig. 4) [21–24,27,28].
Reherniation rate
Lumbar reherniation rates for both groups was reported in eight studies. On analysis, we found that patients who underwent endoscopic lumbar discectomy with annulus fibrosus suturing demonstrated 0.31 times the odds of developing reherniation (OR, 0.31; 95% CI, 0.17–0.55; p=0.00), as illustrated in the forest plot of Fig. 5 [21–23,25–29].
The loss of postoperative intervertebral disc height was another primary outcome of interest; however, due to variability in the method of recording among the studies, a meta-analysis could not be performed. As noted in Table 3 [22,23,26], Fu et al. [22] showed that patients without additional annulus fibrosus repair exhibited greater loss of disc height than did those who underwent annulus fibrosus repair (29.8%±6.2% vs. 22.3%±4.6%, respectively; p<0.01). Ren et al. [23] in 2020 shared similar findings, showing a 6.1% and 8.6% decrease in disc height among those who did and did not undergo annulus fibrosus suturing, respectively. Xi et al. [26] in 2024 provided further data regarding the beneficial outcomes in the suture group, particularly in terms of minimal disc height reduction from preoperative measurements (0.86±0.17 mm) to 12 months’ follow-up (0.87±0.08 mm). Those who did not receive additional suturing exhibited increased reductions in disc height from preoperative measurements (0.78±0.17 mm) to 12 months’ follow-up (0.67±0.18 mm).
Reoperation rate
Reoperation rate was reported in seven studies, with a meta-analysis showing that those who received annulus fibrosus suturing showed a decreased likelihood of needing revision surgery in the future. Those who received annulus fibrosus suturing had 0.26 times the odds of having revision surgery than did those who underwent endoscopic lumbar discectomy alone (OR, 0.26; 95% CI, 0.10–0.68; p=0.01). Fig. 6 presents the forest plot for reoperation rate [21,23,24,26–29]. Zhang et al. [28] was the only study wherein zero revision surgeries were performed in both groups (OR, 1.53; 95% CI, 0.03–80.09; weight=6.03).
VAS back/legs
Although all studies recorded preoperative VAS back scores, only seven studies reported on VAS scores immediate after surgery, whereas six studies reported on VAS scores 3 months after surgery. Owing to the lack of reported correlation coefficients or standard deviations for the change in VAS scores, sensitivity tests were performed for changes in VAS scores immediately after surgery and at the 3-month follow-up using r=0.3, 0.5, and 0.7. Postoperative meta-analysis results showed that patients who underwent endoscopic lumbar discectomy alone exhibited marginally larger decreases in VAS back scores, with a WMD of −0.108 to −0.065. However, no significant differences were observed between the two groups (WMD=−0.065, p=0.558 at r=0.3; WMD=−0.087, p=0.451 at r=0.5; and WMD=−0.108, p=0.373 at r=0.7). At the 3-month follow-up, similar results to postoperative measurements were observed, with a WMD of −0.172 to −0.134, which favored those who underwent endoscopic lumbar discectomy alone. Similarly, no significant difference was found (WMD=−0.134, p=0.3788 at r=0.3; 3 months: WMD=−0.153, p=0.3287 at r=0.5; and WMD=−0.172, p=0.145 at r=0.7). CIs and complete statistical analysis results are summarized in Table 4.
Only seven studies reported on preoperative and postoperative VAS leg scores, whereas only five reported on 3-month follow-up measurements. Similar sensitivity tests were also performed. Meta-analysis of postoperative scores again showed that patients who underwent endoscopic lumbar discectomy alone had marginally larger decreases in VAS leg measurements, with a WMD of −0.203 to −0.197. No significant difference was noted (WMD=−0.197, p=0.191 at r=0.3; WMD=−0.200, p=0.1798 at r=0.5; or WMD=−0.203, p=0.1698 at r=0.7). At the 3-month follow-up, similar results were noted, with a WMD of −0.113 to −0.096. Similarly, no significant difference was noted (WMD=−0.096, p=0.6377 at r=0.3; WMD=−0.105, p=0.6064 at r=0.5; or WMD=−0.113, p=0.5785 at r=0.7). CIs and complete statistical analysis results are shown in Table 5.
Oswestry Disability Index
A total of seven studies reported on preoperative ODI scores, whereas six studies reported on ODI scores both immediately after surgery and at the 3-month follow-up. Similar to VAS scores, sensitivity tests were also performed. Meta-analysis of postoperative ODI scores showed that patients who underwent both endoscopic lumbar discectomy and annulus fibrosus suturing showed greater decreases in ODI with a WMD of 2.39–2.553. These scores were consistent at all correlation coefficients, although not quite significant (WMD=2.39, p=0.0782 at r=0.3; WMD=2.502, p=0.0723 at r=0.5; and WMD=2.553, p=0.0681 at r=0.7). Analysis of the 3-month follow-up changes revealed similar results with a WMD of 1.017–1.285, favoring those receiving additional annulus fibrosus suturing. Although not quite significant, scores remained consistent (WMD=1.017, p=0.144 at r=0.3; WMD=1.147, p=0.1033 at r=0.5; and WMD=1.285, p=0.0697 at r=0.7). CIs and complete statistical analysis results are summarized shown in Table 6.
Quality assessment
The Newcastle-Ottawa Scale was used to assess the quality of the included studies, as shown in Appendix 1. Based on the guidelines, the quality of studies was high, ranging from 7 to 9. Each study was awarded a star for representativeness of the exposed cohort, ascertainment of exposure, demonstration that the outcome of interest was not present at the start of the study, outcome assessment, follow-up duration, and follow-up adequacy.
Publication bias
Publication bias was assessed using funnel plots (Appendices 2–6). Any asymmetries and outliers noted were then subjected to a random-effects model analysis to account for the large variation. Egger’s regression intercept was also performed to determine the significance of the publication bias. In all funnel plots, we determined that publication bias was insignificant (p>0.05).
Discussion
This systematic review has been the first to compare the outcomes of endoscopic lumbar discectomy with and without annulus fibrosus repair. The rationale behind this study stems from the current gap in the literature, which suggests that although minimally invasive endoscopic lumbar discectomies have provided massive improvements in reducing surgical morbidity, recovery times, and improving patient-reported outcomes, minimal improvements in the prevention of disc reherniation and reoperation has still been noted. This crucial issue lies in the very nature of a discectomy procedure, involving either a preexisting or operative incision of the annulus fibrosus, which inevitably compromises the disc’s structural integrity. By compiling data from multiple studies, this systematic review aimed to clarify the benefits of repairing the annulus fibrosus via sutures while providing clinicians with sufficient evidence to effectively guide their patients through surgical expectations and outcomes.
The meta-analysis conducted in the current systematic review found that the most clinically significant findings were reduction of reherniation and reoperation rates, which are the primary objectives of this study. This outcome addresses one of the most feared complications with isolated discectomy procedures, that is, the unfortunate necessity of revision surgeries for reherniations at the same disc segment. Although not directly comparative, the findings from Gong et al. [30] in 2025 and Li et al. [31] in 2024 support this conclusion after having demonstrated zero herniations from their retrospective analyses of lumbar endoscopic discectomy with annulus fibrosus repairs in 21–22 patients. Although not abundant, various novel techniques are currently being explored, including the use of biologics, hydrogels, or biomaterial scaffolding. In fact, Ongini et al. [16] in 2025 showed that biologic integration of polyethylene terephthalate scaffolding is already a viable alternative, significantly reducing the risk of reherniation by 71% through the dramatic increase in necessary compressive force to induce herniation.
Notably, even with the benefits of reduced reherniation and revision rates, these benefits must be weighed against the consistent findings of increased operative time and blood loss with annulus fibrosus repair. Our findings showed that the additional repair to increase operative time and blood loss was on average 9 minutes and 2 mL. Though minimal, the risks of adverse events associated with prolonged operative time should not be disregarded, such as surgical site infections, thromboembolic events, formation of a hematoma, or anesthesia-related complications [32–34]. This finding is especially prevalent for surgeries exceeding 3–5 hours, with the literature showing a 14% increase in the likelihood of complications for every additional 30 minutes of operative time [35]. Despite the potential increase in adverse complications, the reduction in reherniation and revision may be viewed as an acceptable trade-off for most patients and surgeons.
The heterogeneity in VAS pain scores and ODI functional outcomes presents a complicated issue. Although both endoscopic lumbar discectomy with and without annulus fibrosus suturing promoted decreases in VAS and ODI scores, no significance difference among the groups was observed, suggesting that annulus fibrosis suturing was not associated with patient-reported outcomes. Literature on common spinal procedures and pathologies continues to report on extreme postoperative variability in functionality scores considering the many uncontrollable external factors that can heavily influence these outcomes. These can include, but are not limited to, unrealistic patient expectations, prior psychosocial distress, prior low quality of life, and increased preoperative duration of pain [36–38]. Specific to this systematic review, given the need to add an additional procedure, surgical skill must consider poorly placed sutures or accidental damage to neighboring tissues, which can inadvertently affect healing and inflammation [39,40].
The postoperative indications for degenerative disc disease and possible reherniation are measured through the intervertebral disc height. This measurement represents a critical parameter, considering that the literature has repeatedly shown an intimate relationship between the loss of intervertebral disc height and subsequent degenerative and arthritic properties [41,42]. Mechanistically, as the intervertebral disc height decreases, an increased amount of compressive and rotational stress is placed on the spine, further accelerating degeneration [43,44]. Unfortunately, despite the importance of this measurement, only a few studies have reviewed disc height measurements, whereas those that did had varying methods of recording, further complicating statistical analysis or the collection of evidence needed to establish definitive conclusions. This lack of reported outcomes signifies a prominent gap in the current literature, highlighting the need for further studies to incorporate standardized radiographic assessment of disc height preservation as a primary outcome measure.
Several important limitations of this systematic review must be acknowledged. The meta-analysis was performed on only nine studies, reflecting the relative novelty of endoscopic annulus repair and the limited amount of high-quality comparative research available. Additionally, the lack of standardized criteria for patient selection, along with varying ages, gender, medical history, and body mass index, introduce confounding variables that can influence postoperative outcomes. In fact, we noted that the heterogeneity in surgical and suture techniques employed across studies was one methodological limitation of the current study that affected the generalizability of our findings. Another limitation was the lack of explicitly records on the type of herniation in most studies despite these distinctions being influential in treatment approach and outcomes. The absence of standardized measurements for the loss of disc height across the included studies prevented a meta-analysis of this outcome, highlighting a critical gap in evidence that should be addressed in future research by implementing uniform measurements. Considering the lack of reported correlation coefficients in VAS and ODI, assumptions were made (r=0.3, r=0.5, and r=0.7 for changes in VAS and ODI), and actual correlation coefficients may have substantially differed, possibly affecting statistical reliability. Although Eggers’ test did not detect any publication bias across our outcomes, this does not confirm the absence of actual bias, particularly due to the low number of studies included in our meta-analysis. Importantly, owing to the nature of endoscopic surgeries with continuous irrigation, the interpretation of blood loss findings had limited validity, complicating the accurate quantification of true blood loss. Lastly, although patient follow-up was well documented, the timing of the follow-up varied slightly across studies, ranging from 12 to 36 months. Future research should focus on larger-scale randomized controlled trials with standardized patient criteria, uniform outcome measurement methods, and longer follow-up periods to determine whether these beneficial surgical outcomes are maintained long term. Lastly, comparative studies should be performed on other available types of annulus fibrosus repair, with the goal of providing additional alternative solutions to prevent reherniation.
Conclusions
Lumbar endoscopic discectomy with annulus fibrosus suturing promoting a significant increase in operative time but also reduced the reherniation and reoperation rate. No significance differences in hospital length of stay or blood loss were noted between the groups. Although not significant, conflicting results for VAS and ODI scores were noted, with patients who underwent endoscopic lumbar discectomy with annulus fibrosus suturing generally exhibiting better ODI outcomes but worse VAS scores.
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