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Lumbar Spine/Surgical Technique

Mechanical and Biological Treatments for Annulus Fibrosus Repair and Closure: A Review of Clinical Studies

Noah Willett1orcid, Chibuikem A. Ikwuegbuenyi1orcid, Evan Wang1orcid, Lawrance K. Chung1orcid, Anthony Robayo1orcid, Albert Antar1orcid, Galal Elsayed1orcid, Gianluca Vadalà2,3orcid, Ibrahim Hussain1orcid, Roger Härtl1orcid, AO Spine Knowledge Forum Degenerative
Neurospine 2026;23(1):117-144.
Published online: January 31, 2026

1Department of Neurological Surgery, Och Spine at New York Presbyterian Hospital, Weill Cornell Medicine, New York, NY, USA

2Research Unit of Orthopaedic and Trauma Surgery, Departmental Faculty of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy

3Operative Research Unit of Orthopaedic and Trauma Surgery, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy

Corresponding Author Roger Härtl Department of Neurological Surgery, Och Spine at New York Presbyterian Hospital, Weill Cornell Medicine, 525 East 68th Street, Box 99 New York, NY 10065, USA Email: roh9005@med.cornell.edu
• Received: November 16, 2025   • Revised: January 2, 2026   • Accepted: January 6, 2026

Copyright © 2026 by the Korean Spinal Neurosurgery Society

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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  • To address disc reherniation, several annular repair strategies have been developed, including implantable devices, suture-based techniques, and biomaterials. This review evaluates the clinical evidence supporting these strategies. A systematic search of PubMed, Cochrane, and Embase and MEDLINE via Ovid was performed from database inception to July 2025. A combination of keywords was used in the search string. Publications were included if they were clinical studies and described closing the annulus or blocking the annulus defect with biologics, sutures, or physical devices. Exclusion criteria were animal studies, in vitro studies, non-English articles, and abstracts. A single-arm proportional meta-analysis was performed for studies reporting extractable reherniation, reoperation, or complication data. The initial search identified 1,349 records. After removal of 315 duplicates, 1,034 studies underwent screening, with 84 full texts reviewed and 62 meeting inclusion criteria. Forty-one studies (66%) assessed implantable physical devices, of which 40 (98%) evaluated the Barricaid annular closure device (ACD) (Intrinsic Therapeutics, Inc., USA). Eighteen studies (29%) evaluated suture-based closure of the annulus fibrosus, using preloaded devices, bone-anchored systems, or manual suturing techniques. Three studies (5%) examined the use of biomaterials as either an adjunct or standalone method in the form of autologous conditioned plasma, bone marrow stromal cells, and fibrin sealant. For physical devices, the pooled reherniation, reoperation, and complication rates were 4.71%, 4.84%, and 1.76% respectively. Suture-based techniques had reherniation, reoperation, and complication rates of 1.37%, 0.35%, and 0.28%, respectively. For biomaterial-based approaches, only a pooled reherniation rate was calculated (2.11%), as insufficient data were available to pool reoperation and complication rates. Annular repair following discectomy is associated with low rates of reherniation, reoperation, and complications across physical devices, suture-based techniques, and biomaterial approaches. Physical devices and suturing techniques have robust clinical evidence and show generally favorable outcomes, but results remain mixed and heterogenous across techniques. Biomaterials demonstrate early promise but are limited by small study size and short follow-up. While pooled proportional meta-analysis supports the overall safety and effectiveness of annular repair, heterogeneity and limited comparative evidence prevent determination of relative superiority.
  • Keywords: Disc herniation, Annulus fibrosus, Repair
Lumbar disc herniation involves disruption of the annulus fibrosus, leading to nucleus pulposus extrusion outside the disc space [1]. This can result in compression of adjacent nerve roots, leading to radicular leg pain and neurologic deficits [2,3]. As such, disc herniation is a common cause of lower back and leg pain, affecting 1%–3% of the population each year, with a relatively early onset at a mean age of 45 years old [4-7]. When conservative measures fail, lumbar discectomy is the standard surgical treatment and typically provides effective symptom relief. However, same-level reherniation occurs in a relatively high rate of patients after discectomy with the reported range being from 4%–31% [8-12].
Preclinical studies have explored potential annular repair modalities as a means of preventing reherniations. In vitro and cadaveric models have been used to evaluate sutures, patches, adhesives, and hydrogels for their ability to reduce intradiscal pressure and preserve range of motion [13,14]. Computational models have been used to simulate disc herniations; however, these are generally model specific, non-generalizable, and fail to capture the degenerative progression of herniations [15]. In vivo studies have evaluated implantable annular closure devices (ACDs), suture techniques, and gels to determine effects on disc healing and reherniation risk [16-19]. These preclinical investigations support the feasibility and rationale for annulus fibrosus repair. However, the variability of herniation models for in vivo studies presents a challenge, and the translation of some repair methods to humans remains to be tested.
Three repair paradigms that have advanced to clinical evaluation are physical devices that block the annulus defect, suture techniques that directly close the annulus fibrosus, and biomaterials designed to either close the tissue alone or augment another repair strategy [20-22]. For this review, we performed a systematic literature search of clinical studies evaluating annular repair techniques and summarized the available clinical studies on annular repair techniques and their evidence in a narrative framework. Our objective is to provide a comprehensive overview of the current state of annular repair strategies used in humans, evaluate their potential to reduce disc reherniation and reoperations rates, and highlight directions for future research in this field.
A systematic literature review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and was registered in the PROSPERO database (ID: CRD420251081623). PubMed, Cochrane, and Embase and MEDLINE via Ovid were searched from database inception to July 2025. A combination of keywords was utilized to capture a comprehensive array of studies related to annulus fibrosus repair. Keywords included “disc herniation,” “intervertebral disc displacement,” and “annular device.” The search strings queries used can be found in Supplementary Material 1.
1. Inclusion Criteria
Publications were included if they were clinical studies and described closing the annulus or blocking the annulus defect with biologics, sutures, or physical devices.
2. Exclusion Criteria
Publications were excluded if they were animal studies, in vitro studies, not published in English, or abstracts.
3. Study Selection
Articles extracted from the literature search were exported into Rayyan (Cambridge, MA, USA), a professional research software commonly used by investigators for ease of study decision making, where duplicates were identified and removed. Two reviewers (NW and CAI) independently screened titles and abstracts against the inclusion and exclusion criteria. Full texts of selected articles were then similarly reviewed. Discrepancies were resolved through discussion between the 2 reviewers, with unresolved disputes being resolved by senior authors (GE and IH).
4. Data Extraction
Extracted data included title, author, year, country, annulus fibrosus closure technique, study size, study design, follow-up period, reherniation rate, reoperation rate, disc height changes, endplate changes, patient-reported outcomes, and complications.
5. Study Inclusion for Meta-analysis
Studies were considered eligible for inclusion in the single-arm proportional meta-analysis if they reported extractable data on reherniation, reoperation, or complication rates following annular repair. To maintain methodological consistency, studies were pooled within technique-specific categories, including implantable physical devices, suture-based repair techniques, and biomaterial-based approaches. Reherniation was defined as any reported recurrence, including both symptomatic and asymptomatic events. Reoperation was defined as any subsequent surgical intervention at the index level, regardless of indication. Complications were defined as any reported postoperative adverse events.
When multiple publications appeared to originate from the same patient cohort, only the study with the largest sample size and/or the longest follow-up period was included to avoid duplication of data. Studies were excluded from the meta-analysis if outcome measures were not clearly reported, if the sample size was fewer than 10 patients, or if follow-up duration was insufficient to assess the outcome of interest.
Due to substantial heterogeneity in study design, patient selection, surgical techniques, and outcome definitions, direct comparative meta-analysis between annular repair strategies was not performed. Comparative meta-analysis of ACD studies was not undertaken because this has been previously addressed in dedicated meta-analyses, and suturing techniques were not pooled comparatively due to variability and insufficient clarity regarding technical equivalence across studies [23].
6. Risk of Bias Assessment
Methodological quality was evaluated using study design specific appraisal tools for studies included in the meta-analysis portion of the review. Case series were assessed using the Joanna Briggs Institute critical appraisal checklist, cohort and case-control studies were evaluated with the Newcastle-Ottawa Scale, and randomized controlled trials were assessed using the Cochrane Risk of Bias Tool.
Risk of bias assessments were performed independently by 2 reviewers from the study team (NW and CAI). Discrepancies were resolved through discussion. Detailed results of the quality assessment are provided in Supplementary Tables 1-3 and Supplementary Fig. 1.
7. Statistical Analysis
A proportional meta-analysis was performed to estimate pooled reherniation rates, reoperation rates, and complication rates, with corresponding 95% confidence intervals (CIs). Statistical analyses were conducted using the metaprop function in R ver. 4.4.1 (R Foundation for Statistical Computing, Austria). Between-study heterogeneity was assessed using the I2 statistic. The I2 values were interpreted cautiously given the tendency for proportional meta-analyses to yield elevated heterogeneity estimates that do not necessarily reflect true inconsistency across studies.
A random-effects model was applied to account for anticipated clinical and methodological variability among included studies. Given the expected low event rates, pooled estimates were generated using a generalized linear mixed-effects model with logit transformation.
Publication bias was evaluated qualitatively using funnel plot inspection, with acknowledgement of the limitations of this approach in proportional meta-analysis (Supplementary Figs. 2-8).
A total of 1,349 records were identified through PubMed, Embase, MEDLINE, and Cochrane. After removal of 315 duplicates, 1,034 records were screened by title and abstract, of which 910 were excluded. Of the 84 full-text articles, 22 were excluded, resulting in 62 studies included in the review. The PRISMA flow chart summarizes these findings (Fig. 1).
The publication years ranged from 2012 to 2025. The countries of origin were, a multinational trial with participating countries of Germany, Switzerland, Austria, Belgium, Netherlands, and France (n=20), China (n=18), Germany (n=5), Croatia (n=3), Korea (n=3), United States (n=3), Russia (n=2), Switzerland (n=2), Iran (n=1), Spain (n=1), Germany and Austria (n=1), a multinational trial with participating countries of Germany, Croatia, and Netherlands (n=1), Germany and Croatia (n=1), and Belgium (n=1). Forty-one of the studies (66%) examined physical devices designed to plug the annulus defect, 18 studies (29%) examined a suturing technique to repair the annulus, and 3 studies (5%) examined a biomaterial as an adjunct to repairing the annulus.
Risk of bias was assessed for all studies included in the meta-analysis. Among the cohort and case-control studies, 79% (14 of 17) were rated as good quality and 21% (3 of 17) as poor quality. The 2 randomized controlled trials were rated as having a low risk of bias. For case series, 100% (16 of 16) of the studies had an overall score of 70% or above. Risk of bias scoring details are presented in Supplementary Fig. 1.
1. Summary of Annular Repair Strategies
For physical devices, 41 studies (66%) (Table 1) evaluated the use of an implantable physical device to block or cover the annular defect to prevent recurrent herniation (Fig. 2). Nearly all of these (n=40, 98%) investigated the Barricaid ACD (Intrinsic Therapeutics, Inc., USA). A large multinational prospective randomized controlled trial consisting of 550 patients produced data for 19 of the 40 studies (48%) [11,20,24-40]. The only non-ACD used was reported by Godino et al. [41] They evaluated the DISC Care Hernia Blocking System (DCHBS) (NEOS Surgery S.L., Spain) in a prospective study. Eighteen studies (29%) (Table 2) solely evaluated suture-based closure of the annulus fibrosus, using preloaded devices, bone-anchored systems, or manual suturing techniques [21,42-58]. An additional 2 suture cohorts were included in the meta-analysis arising from 2 biomaterial studies that had suture-only cohort comparison groups [59,60].
Preloaded suturing devices were reported in 11 studies (61%) [21,43,44,50,52-56,58]. Five (27%) used the “Disposable Annulus Suture” device, all with control cohorts. The “Disposable Annulus Stapler” was evaluated in 4 studies (22%). Fu et al. [50] evaluated the Star-S Suturing System (2020 Medical Technology Co., Ltd., China) in a retrospective controlled study. Bailey et al. [21] conducted a randomized controlled trial using the Xclose device (Anulex Technologies, USA).
Bone-anchored suturing techniques were described in 2 studies (11%). Suh et al. [46] reported on the use of the PushLock implant (Arthrex, USA) in a retrospective case series. Wang et al. [49] described a bone-anchoring suture technique in a retrospective case series. Manual suture techniques were reported in 5 studies (28%) and were performed with needle-guided or endoscopic systems [42,45,47,48,57].
Three of the 62 studies (5%) (Table 3) examined the use of biomaterials as either an adjunct or standalone method for annular fibrosus repair [22,59,60]. Li et al. [59] conducted a prospective study on autologous conditioned plasma used in addition to a suturing technique. Torkian et al. [22] examined the utility of using fibrin sealant applied to annular defect after discectomy. Xu et al. [60] performed a prospective study on the use of bone marrow stromal cells (BMSCs) as an adjunct to suturing the annulus fibrosus.
2. Reherniation Rates
For physical devices, reherniation rates were reported in 34 studies [11,20,24,25,27,29-33,36-40,61-79]. A total of 12 studies were included to calculate the pooled reherniation rate of 4.71% (95% CI, 2.62–8.34; I2=70.9%) [41,61,63,65-70,73-75]. Fig. 3A displays the forest plot of individual study reherniation rates and confidence intervals contributing to the pooled estimate for physical ACDs.
Among suture techniques, 19 studies were used to calculate the pooled reherniation rate of 1.37% (95% CI, 0.52–3.54; I2=0.0%) [42–60]. Fig. 3B presents the forest plot of individual study reherniation rates and confidence intervals contributing to the pooled estimate for suture-based annular repair techniques.
All 3 biomaterial studies were used to calculate the pooled reherniation rate of 2.11% (95% CI, 0.09–34.4; I2=0.0%) [22,59,60]. Fig. 3C displays the forest plot of individual study reherniation rates and confidence intervals contributing to the pooled estimate for biomaterial augmented annular repair strategies.
3. Reoperation Rates
For physical devices, reoperation rates were reported in 33 studies (80%) [11,20,24,25,27-29,31-34,36-39,61,64-80]. A total of 11 studies were included to calculate the pooled reoperation rate of 4.84% (95% CI, 2.73–8.42; I2=52.6%) [41,61,65-70,73-75]. Fig. 4A displays the forest plot of individual study reoperation rates and corresponding confidence intervals contributing to the pooled estimate for physical ACDs.
Among suture techniques, 11 studies were used to calculate the pooled reoperation rate of 0.35% (95% CI, 0.03–3.48; I2=6.5%) [21,42,44,47-52,54,57]. Fig. 4B presents the forest plot of individual study reoperation rates and confidence intervals contributing to the pooled estimate for suture-based annular repair techniques.
None of the biomaterial studies reported reoperation rates.
4. Complication Rates
For physical devices, complications were reported in 27 studies [11,20,24,25,27–29,31,32,37-39,63,65-69,71,73-77,79-81]. Reported complications included device-related incidents, dural tears, hematomas, and infection. A total of 11 studies were included to calculate the pooled complication rate of 1.76% (95% CI, 0.33–8.90; I2=33.5%) [41,63,65-69,73-75,81]. Fig. 5A displays the forest plot of individual study complication rates and corresponding confidence intervals contributing to the pooled estimate for physical closure devices.
Among suture techniques, 15 studies were used to calculate the pooled complication rate of 0.28% (95% CI, 0.02–3.60; I2=0.0%) [21,42,44-46,49-52,54-58,60]. Fig. 5B presents the forest plot of individual study complication rates and confidence intervals contributing to the pooled estimate.
Only 1 biomaterial study reported an associated complication rate [60].
5. Disc Height
For physical devices, disc height was reported in 10 studies (2 4%) [11,25,63,67,68,72,75,77,78,80]. Among suture techniques, 7 studies measured disc height [42,46,47,49,50,53,55]. One biomaterial study reported on disc height [60].
6. Endplate Changes
For physical devices endplate changes were reported in 11 studies (27%) [11,20,25–27,31,61,66,70,75,78]. None of the studies involving suture techniques or biomaterials reported on endplate changes.
7. Patient-reported Outcomes
For physical devices, patient-reported outcomes in the form of visual analogue scale (VAS) or Oswestry Disability Index (ODI) were reported in 33 studies (80%) [11,20,25-31,33,34,36,39,40,61,63-68,70-81]. Among suture techniques, all studies reported VAS or ODI outcomes [21,42-58]. All 3 biomaterial studies reported VAS or ODI outcomes [22,59,60].
This systematic review and proportional meta-analysis included 62 studies evaluating annular repair following discectomy. Pooled analyses from 34 studies showed low rates of reherniation, reoperation, and complications across repair strategies. Implantable physical devices demonstrated pooled reherniation and reoperation rates of approximately 5%. Suture-based techniques showed lower pooled rates for both reherniation and reoperation. Biomaterial approaches were less frequently studied and demonstrated low pooled reherniation rates, but data on reoperations and complications were limited. Complication rates were low across all techniques. Patient-reported outcomes improved after surgery across all repair strategies. Disc height and endplate outcomes were inconsistently reported across repair strategies limiting any comparative interpretation.
1. Summary of Annular Repair Strategies
The ACD consists of a titanium bone-anchor and attached polyester mesh (Fig. 6) [20]. The other physical device reported in this review, the DCHBS, was first marketed in 2023 and consists of a titanium screw that implants into an adjacent vertebral body with an attached polyester barrier.
Preloaded suturing devices accounted for the largest subset of studies. The “Disposable Annulus Suture” device and “Disposable Annulus Stapler” were reported in 5 and 4 studies respectively, although it remains unclear if these represent distinct devices or different names for the same technology. Only 1 study reported the Chinese utility model patent number and Food and Drug Administration of Beijing, Registration Certificate Number for the Disposable Annulus Suture device, while another study identified the manufacturer of the Disposable Annulus Stapler (2020 Medical Technology Co., Ltd., China) [54,59]. Attempts to further confirm the device’s origin were unsuccessful.
Three studies investigated biomaterial strategies for annulus fibrosus repair, either as adjuncts to suturing or as a standalone application. The suturing was conducted using the “Disposable Annular Stapler”. The third study evaluated fibrin sealant applied directly to the annular defect following a discectomy [22].
2. Reherniation Rate
Across annular repair strategies, independently pooled proportional meta-analysis demonstrated low reherniation rates, with physical devices showing a pooled rate of 4.71%, suture techniques 1.37%, and biomaterial approaches 2.11%. Although suture-based techniques demonstrated a lower pooled reherniation rate when examined as independent single-arm estimates, these data were not derived from direct comparisons and should be interpreted as hypothesis-generating rather than evidence of comparative superiority. Comparative studies are required to determine whether observed differences reflect true technique-related effects or underlying differences in patient selection and study design.
Within individual technique categories, studies that directly compared annular repair with discectomy alone consistently reported lower reherniation rates in patients receiving a repair strategy. For physical devices, a recent meta-analysis demonstrated that the ACD significantly reduced symptomatic reherniation compared with discectomy alone [23]. Similarly, across suture- based techniques, individually controlled studies generally reported lower reherniation rates in repair cohorts relative to controls [42,45,47,48,57]. However, these studies were frequently limited by small sample sizes, short follow-up durations, and substantial heterogeneity in technique. This restricts the generalizability of these findings despite favorable outcomes.
Biomaterial studies had a pooled reherniation rate of 2.11%. One study reported a higher reherniation rate in the fibrin sealant cohort compared with controls (11.7% vs. 5.5%, respectively) [22]. The authors suggested that this may be due to how patients were selected. Fibrin sealant was only used in patients with defects greater than 5 mm, while the control group had smaller defects. Intuitively, patients with large annular defects are at a higher risk of symptom recurrence and reoperation than those with small defects [82]. This finding underscores the importance of accounting for defect size when interpreting outcomes and planning annular repair strategies.
3. Reoperation Rate
Reoperation is a clinically meaningful outcome, as it may reflect failure of the index procedure through either recurrent reherniation or indirect structural changes at adjacent levels. Across annular repair strategies, independently pooled proportional meta-analysis demonstrated low reoperation rates, with physical devices showing a rate of 4.84% and suture techniques of 0.35%. Reoperation outcomes were not pooled for biomaterial approaches due to insufficient reporting.
Interpretation of reoperation rates for physical devices is complicated by variability in definitions. While some studies reported only reoperations for symptomatic same-level reherniation, others included procedures performed for adjacent-level disease, device-related complications, or progression to fusion. Within controlled studies, reoperation rates ranged from 4% to 26.3% in control cohorts and 0% to 16% in patients treated with ACD. Despite these ranges, a recent meta-analysis found no significant difference in overall reoperation rates between patients treated with ACD versus discectomy only patients, suggesting that reduction in reherniations may not result in fewer reoperations [23].
Among suture techniques, the pooled reoperation rate was 0.35%. However, findings across individual studies vary. Several controlled studies report lower rates of reoperation in sutured cohorts compared with controls [44,48,50,51,54]. The largest randomized controlled trial using the Xclose device, which included 700 patients, found no significant difference in reoperation rates between groups [21]. This discrepancy highlights the need for caution in interpreting smaller positive series. It suggests that the effectiveness of annular suturing is not uniform across devices and may depend on design, technique, or patient selection rather than the concept of closing the annulus itself.
Reoperation rates were not reported in the 3 biomaterial studies [22,59,60]. Furthermore, only one study reported a follow-up duration greater than 11 months, limiting the reliability of the reported reoperation rates. As a result, meaningful conclusions regarding the clinical impact of biomaterial augmentation on reoperation risk cannot be drawn from the current clinical literature.
4. Complication Rate
Complication rates are an important clinical consideration, as they inform procedural safety and the balance between potential benefit and additional risk.
Although the pooled complication rate for physical devices was low at 1.76%, device-specific risks highlight the importance of surgeon training and patient specific anatomy. Thomé et al. [20] reported barriers to successful ACD placement in 3.3% of patients, including inaccurate mesh deployment and nerve root proximity. At 5 years of follow-up, 5.2% of patients experienced device failure, with 4.5% of patients requiring device removal and 0.75% undergoing removal with fusion [11]. Burkhardt and Oertel [83] described a case of mesh migration compressing a nerve root, necessitating removal of the mesh and associated scar tissue; the anchor was left in place due to its fixation in the vertebral body.
For suture techniques, the pooled rate of complication was 0.28%. Reported complications were infrequent and included both intraoperative and postoperative events as defined by individual studies. These primarily consisted of dural tears, cerebrospinal fluid leak, and postoperative hyperesthesia, possibly due to nerve root compression and traction [21,42].
One biomaterial study reported no complication across cohorts at 24 months of follow-up [60]. Although limited by sample size, these finding suggest that the addition of BMSCs to discectomy did not increase complication risk within the reported follow-up period.
5. Disc Height
Disc height was evaluated as a secondary structural outcome in studies of annular repair, although reporting was inconsistent across techniques and study designs.
Among studies evaluating physical devices, disc height outcomes were variably reported. In single-arm studies, only one study reported a statistically significant decrease in disc height [78]. In controlled studies, a single trial reported significantly greater postoperative disc height in the ACD cohort compared with controls, while the remaining studies reported no significant differences between groups [63]. Overall, disc height was generally maintained across most studies despite heterogeneity in measurement methods and reporting.
For suture techniques, disc height changes were reported in a limited number of studies [42,46,47,49,50,53,55]. Three controlled studies demonstrated significantly less postoperative disc height loss in the suture cohorts compared with the control cohorts. Only one study reported a significantly greater disc height loss postoperatively. These mixed findings may reflect variability in surgical technique or extent of disc removal, limiting definitive conclusions on the effect of annular suturing on disc height preservation.
Xu et al. [60] reported significantly lower disc height loss in the suture plus BMSC group compared to both the control and suture- only groups. This finding may reflect a more favorable intervertebral disc microenvironment associated with biologic augmentation, suggesting that biologic therapies may promote disc height preservation beyond the effects of mechanical closure alone. This interpretation is supported by preclinical studies demonstrating that BMSC injection into degenerated rabbit intervertebral discs can maintain disc height [84,85].
7. Endplate Changes
Endplate changes were more frequently reported in ACD patients, ranging from 14% to 99% compared to 1.4% to 31.4% in controls [11,20,25-27,31,61,66,70,75,78]. Changes to the endplate at the site of titanium anchor implantation are expected. However, the opposing endplate may also undergo degenerative changes, possibly due to the motion of the mesh blocker exerting pressure on the surface, leading to endplate changes, bone resorption, and eventually Modic changes [26,75]. The clinical significance of these changes remains unclear. Across studies, these changes were not associated with worse patient-reported outcomes.
None of the suture technique or biomaterial studies reported endplate changes, limiting conclusions regarding long-term structural remodeling, particularly when compared to implantable physical devices.
8. Patient-Reported Outcomes
Patient-reported outcomes are important for evaluating the impact of adding annular closure to a discectomy procedure. Patient-reported outcomes were summarized descriptively, as heterogeneity in reporting precluded pooled analysis.
Across 33 ACD studies reporting VAS or ODI scores, patients demonstrated significant postoperative improvement regardless of treatment group. However, comparative findings between ACD and nonintervention cohorts were inconsistent. Twelve studies reported no differences between cohorts, while 7 reported significantly greater improvement in ACD patients [11,20,25-31,33,34,36,39,40,61,63-68,70-81].
For suturing techniques, functional outcomes measured by VAS and ODI improved significantly in all groups. Two studies reported superior improvements in patients treated with suturing compared to control groups [43,51]. Again, however, the largest randomized controlled trial using the Xclose device found no significant difference in VAS and ODI between groups [21].
All 3 biomaterial studies reported greater improvement in VAS scores compared with nonintervention group [22,59,60]. In addition, Xu et al. [60] reported greater improvement in ODI scores. While these findings suggest a potential additional therapeutic benefit associated with biomaterial augmentation, the short follow-up durations limit the strength of conclusions that can be drawn.
9. Future Directions
Future research should prioritize long-term, randomized controlled trials comparing ACD and DCHBS to clarify relative safety, effectiveness, and whether observed benefits are device-specific or reflect a broader class effect of anchored occlusive implants. Beyond these, further device innovation is needed. Emerging designs such as the OctaSeal (Spinal Medical, Israel), which uses 8 atraumatic fixation points, aim to occlude annular defects without requiring bony anchoring or inducing structural endplate remodeling (Fig. 7). Such designs may simplify revisions and reduce implant-related complications.
For suture-based techniques, substantial heterogeneity limits interpretation of existing data. Well-designed comparative trials are needed to determine if outcomes are specific to individual techniques. Standardized radiographic follow-up would allow for better characterization of structural changes over time.
Biomaterial strategies show preliminary promise in reducing reherniation and improving pain and disability outcomes but remain limited by small cohorts and short follow-up. Larger randomized studies with longer follow-up are needed to determine whether observed benefits arise from biologic activity, mechanical closure, or synergistic effects.
Finally, while physical devices and suturing techniques may reduce reherniation rates, it remains unclear whether they promote true biological healing of the annulus fibrosus, which has limited intrinsic regenerative capacity [86]. Biologic repair strategies may enhance long-term healing but lack immediate mechanical support. A combined approach integrating mechanical closure with biologic augmentation may ultimately offer the most effective strategy.
10. Limitations
This review has several limitations that should be considered when interpreting the findings. Substantial heterogeneity existed across the included studies in their design and definitions of key outcomes such as reherniation and reoperation. Some studies defined reherniation radiographically and others relied on clinical symptoms or subsequent interventions, making direct comparisons challenging. Reoperation was also variably defined and could include index-level revision, device-related surgery, or adjacent-level procedures. As a result, direct comparison of absolute reherniation and reoperation rates across studies may be misleading. Follow-up duration varied, with many studies limited to short-term or midterm assessments. As disc degeneration, reherniation and device-related complications may emerge over longer periods, the long-term durability of these interventions remains uncertain. Reporting of radiographic outcomes, such as disc height and endplate changes, was inconsistent and at times qualitative. This limits conclusions regarding structural preservation. Complications were variably reported and may be underrepresented. For physical devices, the evidence is dominated by a single device and an overlapping multinational randomized controlled trial dataset. Some of these studies were partially or fully industry sponsored, which may introduce potential bias and should be considered when interpreting reported outcomes. For suture techniques, methods vary widely and may be technique and operator dependent. For biomaterials, clinical data are preliminary with small, short-term cohorts. Most studies examined repair techniques following discectomy, limiting the ability to generalize these results to other spinal procedures. As a result, the applicability of reported outcomes beyond discectomy remains uncertain.
The meta-analysis is limited by heterogeneity across included studies, including differences in study design, patients selection, technique, and outcome definitions. As a result, direct comparative meta-analysis between annular repair strategies were not feasible. Specifically, ACD studies were not pooled comparatively because this question had been addressed in prior dedicated meta-analysis (ref), while suture-based techniques were not subject to comparative pooling due to variability and insufficient clarity regarding technical equivalence across studies [23].
This systematic review and proportional meta-analysis demonstrate that annular repair following discectomy is associated with low rates of reherniation, reoperation, and complications across physical devices, suture-based techniques, and biomaterial approaches. Independently pooled analyses suggest favorable outcomes for all strategies, although observed differences between techniques should be interpreted as hypothesis generating given the absence of direct comparative data and heterogeneity. While physical devices and suturing techniques show the most robust clinical evidence, each strategy carries technique-specific considerations. Biomaterial approaches show early promise, but current evidence is limited by small cohorts and short follow-up durations. Future studies should prioritize long-term comparative trials.

Conflict of Interest

Dr. Härtl reports consulting for DePuy Synthes, Brainlab, and Aclarion; research support from AOSpine, Nuvasive, Brainlab; investments with Realist and Onpoint all outside the submitted work. The other authors have nothing to disclose.

Funding/Support

This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Author Contribution

Conceptualization: RH; AO Spine Knowledge Forum Degenerative; Data curation: CAI, EW; Formal analysis: CAI; Methodology: NW, CAI; Visualization: NW; Writing – original draft: NW; Writing – review & editing: NW, CAI, EW, LKC, AR, AA, GE, GV, IH, RH.

Supplementary Material 1, Supplementary Tables 1-3, and Supplementary Figs. 1-8 are available at https://doi.org/10.14245/ns.2551626.813.
Supplementary Table 1.
Newcastle - Ottawa Quality Assessment Scale (NOS) - Cohort studies
ns-2551626-813-Supplementary-Table-1.pdf
Supplementary Table 2.
Newcastle - Ottawa Quality Assessment (NOS) Scale - Case-control studies
ns-2551626-813-Supplementary-Table-2.pdf
Supplementary Table 3.
Joanna Briggs Institute (JBI) Critical Appraisal Checklist for case series
ns-2551626-813-Supplementary-Table-3.pdf
Supplementary Fig. 1.
Risk of Bias Cochrane Tool for clinical trials.
ns-2551626-813-Supplementary-Fig-1.pdf
Supplementary Fig. 2.
Funnel plot for the incidence of re-herniation among devices for annular repair.
ns-2551626-813-Supplementary-Fig-2.pdf
Supplementary Fig. 3.
Funnel plot for the incidence of reoperation among devices for annular repair.
ns-2551626-813-Supplementary-Fig-3.pdf
Supplementary Fig. 4.
Funnel plot for the incidence of complications among devices for annular repair.
ns-2551626-813-Supplementary-Fig-4.pdf
Supplementary Fig. 5.
Funnel plot for the incidence of reherniation among sutures for annular repair.
ns-2551626-813-Supplementary-Fig-5.pdf
Supplementary Fig. 6.
Funnel plot for the incidence of reoperation among sutures for annular repair.
ns-2551626-813-Supplementary-Fig-6.pdf
Supplementary Fig. 7.
Funnel plot for the incidence of complication among sutures for annular repair.
ns-2551626-813-Supplementary-Fig-7.pdf
Supplementary Fig. 8.
Funnel plot for the incidence of reherniation among biomaterials for annular repair.
ns-2551626-813-Supplementary-Fig-8.pdf
Fig. 1.
PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) flow diagram describing systematic search and review of the literature.
ns-2551626-813f1.jpg
Fig. 2.
Number of clinical studies included by annular closure technique: physical device (n=41), suture techniques (n=18), biomaterials (n=3).
ns-2551626-813f2.jpg
Fig. 3.
Forest plots of pooled outcomes for reherniation rates: physical devices (A), suture techniques (B), and biomaterials (C), shown with individual study estimates and 95% confidence intervals. Total number of patients used were present at final follow-up. GLMM, generalized linear mixed model; CI, confidence interval.
ns-2551626-813f3.jpg
Fig. 4.
Forest plots of pooled outcomes for reoperation rates: physical devices (A) and suture techniques (B) with individual study estimates and 95% confidence intervals. Total number of patients used were present at final follow-up. GLMM, generalized linear mixed model; CI, confidence interval.
ns-2551626-813f4.jpg
Fig. 5.
Forest plots of complication rates: physical devices (A) and suture techniques (B) shown with individual study estimates and 95% confidence intervals. Total number of patients used were present at final follow-up. GLMM, generalized linear mixed model; CI, confidence interval.
ns-2551626-813f5.jpg
Fig. 6.
Physical device reported to occlude the annular defect: Barricaid (Intrinsic Therapeutics, Inc., USA).
ns-2551626-813f6.jpg
Fig. 7.
OctaSeal (Spinol Medical, Israel) device allowing for atraumatic fixation and blocking of defect.
ns-2551626-813f7.jpg
Table 1.
Implantable physical device studies
Table 1.
Title Study Country Technique/device Design Sample (N)* Follow-up (mo) Reherniation rate Reoperation rate Disc height changes Endplate changes Functional outcomes Complications
A new hernia blocking system to prevent recurrent lumbar disc herniation: surgical technique, intraoperative findings and six-months postoperative outcomes Godino et al. [41] 2025 Spain DISC care Prospective case series 30 6 Symptomatic reherniation: 0% 0% At least 75% of disc height maintained in 100% patients Modic type 1 changes in 50% of patients Significant improvement of VAS and ODI 3.30%
Asymptomatic reherniation: 7.4%
Annular closure in lumbar microdiscectomy for prevention of reherniation: a randomized clinical trial Thomé et al. [20] 2018 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Control: 70% ACD: 50% (p<0.001) Control: 16.2% Not reported Control: 30% ACD: 84% (p<0.001) No difference in VAS or ODI between groups Control: 16.6%
Control: 278 ACD: 8.8% (p<0.01) ACD: 7.1% (p=0.001)
ACD: 272
Bone resorption around the annular closure device during a postoperative followup of 8 years Sanginov et al. [61] 2024 Russia Barricaid Retrospective case series 133 85 5.30% 3.00% Not reported Bone resorption 63.6% of patients Significant improvement of VAS and ODI Not reported
Bone-anchored annular closure following lumbar discectomy reduces risk of complications and reoperations within 90 days of discharge Klassen et al. [24] 2017 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 3 Control: 6.8% Control: 5.4% Not reported Not reported Not reported Serious adverse event
Control: 278 ACD: 2.2% (p=0.01) ACD: 1.9% (p=0.03) Control: 16.3%
ACD: 272 ACD: 9.7% (p=0.056)
Device- or procedure-related
Control: 10.2%
ACD: 4.5% (p=0.02)
Cost savings associated with prevention of recurrent lumbar disc herniation with a novel annular closure device: a multicenter prospective cohort study Parker et al. [62] 2013 Croatia Barricaid Prospective case series 76 24 Control: 6.5% Not reported Not reported Not reported Not reported Not reported
Control: 46 ACD: 0.0% (p=0.27)
ACD: 30
Efficacy of a Novel Annular Closure Device after Lumbar Discectomy in Korean Patients: A 24-Month Follow-up of a Randomized Controlled Trial Cho et al. [63] 2019 Korea Barricaid RCT 60 24 Control: 20% Not reported Postoperative disc height Not reported No difference in VAS or ODI between groups 0%
Control: 30 ACD: 3.3% (p=0.044) Control: 10.2 ± 1.2 mm
ACD: 30 ACD: 11.4 ± 1.5 mm (p=0.006)
The high-risk discectomy patient: prevention of reherniation in patients with large anular defects using an anular closure device Bouma et al. [64] 2013 Germany and Croatia Barricaid Prospective case series 75 24 6.50% 1.40% Not reported Not reported Significant improvement of VAS and ODI Not reported
Three-year results from a randomized trial of lumbar discectomy with annulus fibrosus occlusion in patients at high risk for reherniation Kienzler et al. [25] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 36 Control: 29.5% Control: 19.3% Control: 6.4 ± 2.2 mm Control: 41% VAS and ODI significantly better in ACD group Control: 18.7%
Control: 278 ACD: 14.8% (p<0.001) ACD: 11.0% (p=0.007) ACD: 6.3 ± 2.2 mm (p=0.64) ACD: 89% (p<0.001) ACD: 10.7% (p=0.008)
ACD: 272
Surgical experience and complications in 50 patients treated with an anular closure device following lumbar discectomy Ardeshiri et al. [65] 2019 Germany Barricaid Prospective case series 50 12 2% 4% Not reported Not reported Significant improvement of VAS and ODI 4%
Endplate changes after lumbar discectomy with and without implantation of an annular closure device Barth et al. [26] 2018 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Prospective case series 493 12 Not reported Not reported Not reported Superior endplate VAS leg significantly better in ACD group. No difference in other measures Not reported
Control: 251 Control: 31.4%
ACD: 242 ACD: 71.6% (p<0.001)
Inferior endplate
Control: 11.1%
ACD: 56.1% (p<0.001)
Morphology and Clinical Relevance of Vertebral Endplate Changes Following Limited Lumbar Discectomy With or Without Bone-anchored Annular Closure Kuršumović et al. [27] 2018 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid RCT 550 24 Control: 24.0% Control: 13% Not reported Control: 33% No difference in VAS or ODI between groups Higher in control group with vertebral endplate changes compared to ACD group
Control: 283 ACD: 11% (p<0.001) ACD: 5% (p<0.001) ACD: 85%
ACD: 267
Performance of an Annular Closure Device in a ‘Real-World’, Heterogeneous, At-Risk, Lumbar Discectomy Population Kuršumović and Rath. [66] 2017 Germany Barricaid Retrospective case series 171 15 3.50% 7.00% Not reported 14% Significant improvement of ODI and VAS 8.8% of patients had ACD’s mesh detach
Post-lumbar discectomy reoperations that are associated with poor clinical and socioeconomic outcomes can be reduced through use of a novel annular closure device: results from a 2-year randomized controlled trial Klassen et al. [28] 2018 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Control: 25% Control: 16% Not reported Not reported Reoperations led to significantly worse VAS and ODI (p<0.001). Control: 1.1%
Control: 278 ACD: 12% ACD: 9% (p=0.01) ACD: 1.5%
ACD: 272 No difference between groups
Primary Limited Lumbar Discectomy with an Annulus Closure Device: One-Year Clinical and Radiographic Results from a Prospective, Multi-Center Study Lequin et al. [67] 2012 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Prospective case series 45 12 2.40% 2.40% Postoperative disc height: 92.8 ± 7.9% of baseline (p<0.01) Not reported Significant improvement of VAS and ODI 0%
Protecting facet joints post-lumbar discectomy: Barricaid annular closure device reduces risk of facet degeneration Trummer et al. [81] 2013 Germany and Austria Barricaid Prospective 212 12 Not reported Not reported Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 137
ACD: 75
Effect of an Annular Closure Device (Barricaid) on Same-Level Recurrent Disk Herniation and Disk Height Loss After Primary Lumbar Discectomy Two-year Results of a Multicenter Prospective Cohort Study Parker et al. [68] 2016 Croatia Barricaid Prospective case series 76 24 Control: 6.5% Control: 4.3% Postoperative disc height Not reported VAS leg Control: 2.2%
Control: 46 ACD: 0% (p=0.27) ACD: 0% Control: 6.9 ± 1.1 mm Control: 18 ± 18 ACD: 3.3%
ACD: 30 ACD: 7.63 ± 1.5 mm (p=0.054) ACD: 9 ± 20 (p<0.05)
VAS back
Control: 21 ± 22
ACD: 10 ± 19 (p<0.05)
ODI
Control: 21 ± 17
ACD: 11 ± 10 (p<0.05)
Effect of Anular Closure on Disk Height Maintenance and Reoperated Recurrent Herniation Following Lumbar Diskectomy: Two-Year Data Ledic et al. [80] 2015 Croatia, Germany, Netherlands Barricaid Prospective case series 75 24 1.5% 4.00% 92% of patients maintained at least 75% of preoperative disc height Not reported Significant improvement of VAS and ODI 2.70%
Implantation of a bone-anchored annular closure device in conjunction with tubular minimally invasive discectomy for lumbar disc herniation: a retrospective study Martens et al. [69] 2018 Belgium Barricaid Retrospective case series 60 24 3% 5% Not reported Not reported Not reported 0%
Occurrence of discal and non-discal changes after sequestrectomy alone versus sequestrectomy and implantation of an anulus closure device Barth et al. [70] 2016 Germany Barricaid Retrospective case series 85 18 Control: 50% Control: 12.5% Not reported Control: 10.3% No difference in VAS or ODI between groups Not reported
Control: 40 ACD: 4.9% (p<0.001) ACD: 2.2% (p=0.729) ACD: 52.4% (p<0.001)
ACD: 45
Two year real world results of lumbar discectomy with bone anchored annular closure in patients at high risk of reherniation Ardeshiri et al. [71] 2019 Germany Barricaid Prospective case series 75 24 1.40% 4% Not reported Not reported Significant improvement in VAS and ODI 0%
Use of Annular Closure Device (Barricaid®) for Preventing Lumbar Disc Reherniation: One-Year Results of Three Cases Hahn et al. [72] 2014 Korea Barricaid Retrospective case series 3 12 0% 0% Well maintained (no disc height loss at 1 yr) Not reported Significant improvement in VAS Not reported
Effectiveness of an Annular Closure Device to Prevent Recurrent Lumbar Disc Herniation A Secondary Analysis With 5 Years of Follow-up Thomé et al. [11] 2021 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 60 Control: 31.6% Control: 22.6% Disc height loss Control: 1.4% No difference in VAS or ODI between groups Control: 20.5%
Control: 278 ACD: 18.8% (p<0.001) ACD: 16.0% (p=0.03) Control: 1.7 mm ACD: 20.2% (p<0.001) ACD: 12.0% (p=0.008)
ACD: 272 ACD: 1.9 mm (p=0.31)
Lumbar Discectomy With Bone-Anchored Annular Closure Device in Patients With Large Annular Defects: One-Year Results Nunley et al. [73] 2023 United States Barricaid Prospective case series 55 12 3.70% 5.50% Not reported Not reported VAS and ODI Improved by at least minimal clinically important difference 5.0%
Lumbar discectomy with annulus fibrosus closure: A retrospective series of 53 consecutive patients Kurzbuch et al. [74] 2022 Switzerland Barricaid Retrospective case series 53 12 Control: 14.6% Control: 14.6% Not reported Not reported VAS and ODI improved by at least minimal clinically important difference Control: 0%
Control: 41 ACD: 8.3% ACD: 8.3% ACD: 0%
ACD: 12
Incidence and clinical impact of vertebral endplate changes after limited lumbar microdiscectomy and implantation of a bone-anchored annular closure device Kienzler et al. [29] 2021 Switzerland Barricaid Retrospective case series 72 14.67 24% 18% Disc height loss: 0.7 ± 0.6 mm 99% Significant improvement in VAS and ODI Device failure 26.4%
Intraoperative findings, complications, and short-term results after lumbar microdiscectomy with or without implantation of annular closure device Kienzler et al. [29] 2021 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 3 Control: 6.5% Control: 5% Not reported Not reported No significant difference in VAS and ODI between groups Serious adverse events Control: 7.9% ACD: 3.7%
Control: 278 ACD: 1.5% (p=0.004) ACD: 2.2%
ACD: 272
Risk factors for early reherniation after lumbar discectomy with or without annular closure: results of a multicenter randomized controlled study Kienzler et al. [30] 2021 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 3 Control: 6.5% Not reported Not reported Not reported No significant difference in VAS and ODI between groups Not reported
Control: 278 ACD: 1.5% (p=0.004)
ACD: 272
Clinical implications of vertebral endplate disruptions after lumbar discectomy: 3-year results from a randomized trial of a bone-anchored annular closure device Kuršumović et al. [31] 2020 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 36 Control: 29.5% Control: 19.3% Not reported Endplate disruption (n) Significantly improved VAS and ODI in ACD group No serious adverse events
Control: 278 ACD: 14.8% (p<0.001) ACD: 11.0% (p=0.007) Control: 140
ACD: 272 ACD: 436 (p<0.001)
Lumbar Discectomy With Barricaid Device Implantation in Patients at High Risk of Reherniation: Initial Results From a Postmarket Study Nunley et al. [76] 2021 United States Barricaid Prospective case series 55 3 3.60% 1.80% Not reported Not reported VAS improved 98% and ODI improved 95% by at least minimally clinically important difference 5.50%
Lumbar disc reherniation prevention with a bone-anchored annular closure device: 1-year results of a randomized trial van den Brink et al. [32] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 12 Control: 17.3% Control: 12.5% Not reported Not reported Not reported Control: 20.9%
Control: 278 ACD: 8.4% (p=0.002) ACD: 6.6% ACD: 11.2% (p=0.002)
ACD: 272
Reoperation After Primary Lumbar Discectomy with or without Implantation of a Bone-Anchored Annular Closure Device: Surgical Strategies and Clinical Outcomes Klassen et al. [33] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 46.8 Control: 29.5% Control: 19.3% Not reported Not reported Significantly improved VAS and ODI in ACD group Not reported
Control: 278 ACD: 14.8% (p<0.001) ACD: 11.0% (p=0.007)
ACD: 272
Annular closure device lowers reoperation risk 4 years after lumbar discectomy Nanda et al. [34] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 48 Not reported Control: 21.1% Not reported Not reported Significantly improved VAS and ODI in ACD group Not reported
Control: 278 ACD: 14.4% (p=0.03)
ACD: 272
Cost-effectiveness of a Bone-anchored Annular Closure Device Versus Conventional Lumbar Discectomy in Treating Lumbar Disc Herniations Ament et al. [35] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Not reported Not reported Not reported Not reported Not reported Not reported
Control: 278
ACD: 272
Clinical performance of a bone-anchored annular closure device in older adults Bouma et al. [36] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 36 Control: 21.1% Control: 26.3% Not reported Not reported Mean clinically important difference - VAS Control: 70.6% Not reported
Control: 278 ACD: 12.5% ACD: 11.1% ACD: 83.3% ODI
ACD: 272 Control: 70.6%
ACD: 84.6%
Reduction of direct costs in high-risk lumbar discectomy patients during the 90-day post-operative period through annular closure Thaci et al. [37] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 3 Control: 6.8% Control: 4.0% Not reported Not reported Not reported Control: 8.6%
Control: 278 ACD: 2.2% (p=0.01) ACD: 0.7% (p=0.02) ACD: 3.3% (p=0.01)
ACD: 272
Postoperative direct health care costs of lumbar discectomy are reduced with the use of a novel annular closure device in high-risk patients Ament et al. [38] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Control: 13% Control: 21.9% Not reported Not reported Not reported Control: 8 events
Control: 278 ACD: 25% (p<0.001) ACD: 10.7% ACD: 1 event
ACD: 272
Effectiveness of an annular closure device in a “real-world” population: stratification of registry data using screening criteria from a randomized controlled trial Kuršumović and Rath. [77] 2018 Germany Barricaid Retrospective case series 164 15.6 6.8% 6.8% Disc Height Not reported Significant improvement of VAS and ODI 9.10%
Loss: 0.38 ± 0.69 mm
Predictors of Treatment Success Following Limited Discectomy With Annular Closure for Lumbar Disc Herniation Krutko et al. [78] 2020 Russia Barricaid Retrospective case series 133 12 1.50% 3.00% Preoperative: 0.28 ± 0.05 mm End plate resorption increased significantly Significant improvement in VAS and ODI Not reported
Postoperative: 0.24 ± 0.05 mm (p<0.001)
Does Patient Blinding Influence Clinical Outcomes After Annular Closure Device Implantation? A Propensity Score-Matched Analysis Bouma et al. [39] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Blinded: 5.7% Blinded: 8.6% Not reported Not reported No difference in VAS and ODI between groups Blinded: 5.7%
Control: 278 Unblinded: 9.1% (p=0.59) Unblinded: 12.2% (p=0.19) Unblinded: 8.9% (p=0.63)
ACD: 272
Clinical outcomes in patients after lumbar disk surgery with annular reinforcement device: Two-year follow up Vukas et al. [79] 2013 Croatia Barricaid Prospective case series 102 24 Control: 6.9% Control: 6.9% Not reported Not reported Significant improvement in VAS and ODI Durotomy (n)
Control: 72 ACD: 0% ACD: 0% Control: 1
ACD: 30 ACD: 1
Challenges in the Analysis of Longitudinal Pain Data: Practical Lessons from a Randomized Trial of Annular Closure in Lumbar Disc Surgery Bouma et al. [40] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Control: 21.9% Not reported Not reported Not reported No difference in VAS between cohorts in unadjusted analysis. In integrated analysis, VAS significant improved in ACD group Not reported
Control: 278 ACD: 10.3% (p<0.001)
ACD: 272

VAS, visual analogue scale; ODI, Oswestry Disability Index; RCT, randomized controlled trial; ACD, anterior cervical discectomy.

*Total number of patients included in the study.

Table 2.
Suturing technique studies
Table 2.
Title Study Country Technique Design Sample (N)* Follow-up (mo) Reherniation rate Reoperation rate Disc height Endplate changes Functional outcomes Complications
Prospective, Multicenter, Randomized, Controlled Study of Anular Repair in Lumbar Discectomy Bailey et al. [21] 2013 United states Preloaded: Xclose Multicenter RCT 700 24 Not reported Control: 11.2% Not reported Not reported No difference in VAS and ODI between groups Control: 20.5%
Control: 250 Xclose: 9.7% (p=0.562) Suture: 17.6% p=0.34
Xclose: 500
Needle-Guided Suture Technique for Lumbar Annular Fiber Closure in Microendoscopic Discectomy: A Technical Note and Case Series Luo et al. [42] 2020 China Manual: needle-guided annular closure suture Retrospective case series 25 12 0% 0% Mean decrease in disc height (%) 8.11 ± 3.36 Not reported Significant improvement in VAS and ODI 4%
Study on the clinical effect of percutaneous transforaminal endoscopic discectomy combined with annulus fibrosus repair in the treatment of single-segment lumbar disc herniation in young and middle-aged patients Zhao et al. [43] 2024 China Preloaded: disposable annulus fibrosus stapler Retrospective case series 96 12 Control: 14% Not reported Not reported Not reported VAS and ODI significantly improved in suture groups Not reported
Control: 50 Suture: 2.2% (p<0.05)
Suture: 46
Full-endoscopic posterior longitudinal ligament coverage suturing for lumbar disc herniation with annular defects Zhang et al. [44] 2025 China Preloaded: disposable annulus fibrosus suture device Retrospective case series 56 14.3 Control: 17.6% Control: 2.9% Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 34 Suture: 0% (p<0.05) Suture: 0%
Suture: 22
The clinical application of “jetting suture” technique in annular repair under microendoscopic discectomy Qi et al. [45] 2016 China Manual: “Jetting” annular suture under MED Prospective case series 30 26.7 0% Not reported Not reported Not reported Significant improvement in ODI 0%
Repair Using Conventional Implant for Ruptured Annulus Fibrosus after Lumbar Discectomy: Surgical Technique and Case Series Suh et al. [46] 2015 Korea Bone-anchored: No. 2 fiberwire sutures and PushLock implants Retrospective case series 19 36 0% Not reported 2.4 ± 1.3mm (p= 0.08) change in preoperative vs. postoperative Not reported Significant improvement in VAS and ODI 0%
Uni-portal non-coaxial spinal endoscopic surgery combined with annulus fibrosus suture technique for lumbar disc herniation: Case series Li et al. [47] 2025 China Manual: endoscopic suturing Retrospective case series 22 11.3 0% 0% Preoperative Not reported Significant improvement in VAS and ODI Not reported
Control: 9.8 ± 1.5 mm
Suture: 9.5 ± 1.5 mm (p<0.0001)
Clinical effect of full endoscopic lumbar annulus fibrosus suture Peng et al. [48] 2024 China Manual: Endoscopic needle-guided annular suture Retrospective case series 72 12 Control: 12.2% Control: 7.3% Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 41 Suture: 0% (p=0.044) Suture: 0% (p=0.124)
Suture: 31
Bone anchoring annular suture technique for repairing annular defects at vertebral body edge following lumbar discectomy Wang et al. [49] 2025 China Bone-anchored: suture Retrospective case series 84 12.6 1.2% 0% Preop: 9.10 ± 0.75 mm Not reported Significant improvement in VAS and ODI 8.3%
Postop: 9.05 ± 0.82 mm (p=0.070)
Clinical efficacy of single-channel percutaneous endoscopic nucleotomy with annulus fibrosus suturing for lumbar disc herniation: A retrospective study Fu et al. [50] 2024 China Preloaded: STAR-S Suturing System Retrospective 86 12 Control: 9.52% Control: 9.52% Disc height loss rate Not reported No difference in VAS and ODI between groups 0%
Control: 42 Suture: 2.27% (p=0.029) Suture: 2.27% Control: 29.8%
Suture: 44 Suture: 22.3% (p<0.01)
A suture technique combining annulus fibrosis with posterior longitudinal ligament for lumbar disc herniation under endoscopy He et al. [51] 2025 China Preloaded: Disposable Annulus fibrosus Stapler Retrospective case control 412 15.2 Control: 9.3% Control: 3.4% Not reported Not reported VAS and ODI significantly improved in suture groups 0%
Control: 204 Suture: 3.8% (p=0.019) Suture: 0.5% (p=0.03)
Suture: 208
The effcet of annulus fibrosus suture combined with percutaneous transforaminal endoscopic discectomy on obese patients with lumbar disc herniation Zhao et al. [52] 2025 China Preloaded: Disposable Annulus fibrosus Stapler Retrospective 23 12 0% 0% Not reported Not reported Significant improvement of VAS and ODI 0%
Analysis of the clinical efficacy of visualization of percutaneous endoscopic lumbar discectomy combined with annulus fibrosus suture in lumbar disc herniation Xi et al. [53] 2024 China Preloaded: annulus fibrosus suture device Retrospective case control 106 12 Control: 9.59% Not reported Control Preop: 0.76 ± 0.19 mm Not reported No difference in VAS and ODI between groups Not reported
Control: 73 Suture: 3.03% (p=0.027) Postop: 0.67 ± 0.18 mm (p<0.001)
Suture: 33 Suture Preop: 0.86 ± 0.17 mm
Postop: 0.87 ± 0.08 mm (p=0.718)
A retrospective study of the midterm efficacy of full-endoscopic annulus fibrosus suture following lumbar discectomy Wang et al. [54] 2022 China Preloaded: annulus fibrosus suture device Retrospective case series 82 18 Control: 7.1% Control: 7.1% Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 42 Suture: 0% Suture: 0%
Suture: 40
Microendoscopic Discectomy Combined with Annular Suture Versus Percutaneous Transforaminal Endoscopic Discectomy for Lumbar Disc Herniation: A Prospective Observational Study Ren et al. [55] 2020 China Preloaded: annulus fibrosus suture device Prospective case series 135 36 Control: 12.7% Not reported Control: 11.2 ± 1.3 mm Not reported No difference in VAS and ODI between groups 0%
Control: 71 Suture: 6.3% (p=0.170) Suture: 12.0 ± 1.5 mm (p=0.007)
Suture: 64
A Pilot Study of Full-Endoscopic Annulus Fibrosus Suture Following Lumbar Discectomy: Technique Notes and One-Year Follow-Up Li et al. [56] 2020 China Preloaded: Disposable Annulus fibrosus Stapler Prospective case series 50 12 0% Not reported Not reported Not reported Significant improvement in VAS and ODI 0%
Clinical study of Microendoscopic Discectomy + Fibrous Ring Suture Versus Microendoscopic Discectomy alone in the treatment of lumbar disc herniation in young and middle-aged patients Cui et al. [57] 2024 China Manual: microendoscopic suturing Retrospective case series 66 12 Control: 9.1% Control: 9.1% Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 33 Suture: 0% Suture: 0%
Suture: 33
Comparative outcomes of unilateral biportal endoscopic lumbar intervertebral discectomy with and without annulus fibrosus suture in lumbar disc herniation: a retrospective analysis Zhou et al. [58] 2025 China Preloaded: annulus fibrosus suture device Retrospective case series 177 24 Control: 3.6% Control: 5.1% Not reported Not reported No difference in VAS between groups Control: 1.4%
Control: 138 Suture: 0% (p<0.001) Suture: 2.6% Suture: 2.6%
Suture: 39

VAS, visual analogue scale; ODI, Oswestry Disability Index; RCT, randomized controlled trial.

*Total number of patients included in the study.

Table 3.
Biomaterial studies
Table 3.
Title Study Country Technique/device Design Sample (N)* Follow-up (mo) Reherniation rate Reoperation rate Disc height maintenance Endplate changes Functional outcomes Complications
A novel full endoscopic annular repair technique combined with autologous conditioned plasma intradiscal injection: a new safe serial therapeutic model for the treatment of lumbar disc herniation Li et al. [59] 2021 China Disposable Annular Stapler/Autologous conditioned plasma Prospective case series 75 6 Control: 4.0% Not reported Not reported Not reported VAS back Not reported
Control: 25 Suture: 0% Control: 2.00 ± 0.18
Suture: 25 Suture+ACP: 0% Suture: 1.80 ± 0.12
Suture+ACP: 25 Suture+ACP: 0.96 ± 0.14 (p<0.001) VAS leg
Control: 1.96 ± 0.15
Suture: 1.68 ± 0.13
Suture+ACP: 1.48 ± 0.12 (p=0.038)
No difference in ODI
Fibrin sealants in lumbar annuloplasty after endoscopic discectomy as a method to prevent recurrent lumbar disc herniation Torkian et al. [22] 2020 Iran Fibrin sealant Prospective case series 35 10.5 Control: 5.5% Not reported Not reported Not reported VAS Control: 3 (2-5) Not reported
Control: 18 Fibrin: 11.7% Fibrin: 2 (2-4) (p=0.015)
Fibrin: 17
Selective Retention of Bone Marrow Stromal Cells with Gelatin Sponge for Repair of Intervertebral Disc Defects after Microendoscopic Discectomy: A Prospective Controlled Study and 2-year Follow-up Xu et al. [60] 2021 China Disposable Annular Stapler and Bone Marrow Stromal Cells and gelatin sponge Prospective case control 45 24 Control: 0% Not reported Disc height loss Not reported VAS improvement rate 0%
Control: 15 Suture: 0% Control: 29.3% ± 2.2% Control: 71.3% ± 7.0%
Suture: 15 Suture+BMSC: 0% Suture: 27.6% ± 0.7% Suture: 70.1% ± 7.8%
Suture+BMSC: 15 Suture+BMSC: 17.2% ± 1.3% (p<0.05) VAS Suture+BMSC: 80.1 ± 7.6% (p<0.05) ODI improvement rate
Control: 57.8% ± 8.1%
Suture: 59.9% ± 5.5%
Suture+BMSC: 65.6% ± 8.8% (p<0.05)

VAS, visual analogue scale; ACP, autologous conditioned plasma; BMSC, bone marrow stromal cell.

*Total number of patients included in the study.

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Mechanical and Biological Treatments for Annulus Fibrosus Repair and Closure: A Review of Clinical Studies
Neurospine. 2026;23(1):117-144.   Published online January 31, 2026
DOI: https://doi.org/10.14245/ns.2551626.813
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Mechanical and Biological Treatments for Annulus Fibrosus Repair and Closure: A Review of Clinical Studies
Neurospine. 2026;23(1):117-144.   Published online January 31, 2026
DOI: https://doi.org/10.14245/ns.2551626.813
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Mechanical and Biological Treatments for Annulus Fibrosus Repair and Closure: A Review of Clinical Studies
Image Image Image Image Image Image Image
Fig. 1. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) flow diagram describing systematic search and review of the literature.
Fig. 2. Number of clinical studies included by annular closure technique: physical device (n=41), suture techniques (n=18), biomaterials (n=3).
Fig. 3. Forest plots of pooled outcomes for reherniation rates: physical devices (A), suture techniques (B), and biomaterials (C), shown with individual study estimates and 95% confidence intervals. Total number of patients used were present at final follow-up. GLMM, generalized linear mixed model; CI, confidence interval.
Fig. 4. Forest plots of pooled outcomes for reoperation rates: physical devices (A) and suture techniques (B) with individual study estimates and 95% confidence intervals. Total number of patients used were present at final follow-up. GLMM, generalized linear mixed model; CI, confidence interval.
Fig. 5. Forest plots of complication rates: physical devices (A) and suture techniques (B) shown with individual study estimates and 95% confidence intervals. Total number of patients used were present at final follow-up. GLMM, generalized linear mixed model; CI, confidence interval.
Fig. 6. Physical device reported to occlude the annular defect: Barricaid (Intrinsic Therapeutics, Inc., USA).
Fig. 7. OctaSeal (Spinol Medical, Israel) device allowing for atraumatic fixation and blocking of defect.

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Fig. 4.

Fig. 5.

Fig. 6.

Fig. 7.

Mechanical and Biological Treatments for Annulus Fibrosus Repair and Closure: A Review of Clinical Studies
Title Study Country Technique/device Design Sample (N)* Follow-up (mo) Reherniation rate Reoperation rate Disc height changes Endplate changes Functional outcomes Complications
A new hernia blocking system to prevent recurrent lumbar disc herniation: surgical technique, intraoperative findings and six-months postoperative outcomes Godino et al. [41] 2025 Spain DISC care Prospective case series 30 6 Symptomatic reherniation: 0% 0% At least 75% of disc height maintained in 100% patients Modic type 1 changes in 50% of patients Significant improvement of VAS and ODI 3.30%
Asymptomatic reherniation: 7.4%
Annular closure in lumbar microdiscectomy for prevention of reherniation: a randomized clinical trial Thomé et al. [20] 2018 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Control: 70% ACD: 50% (p<0.001) Control: 16.2% Not reported Control: 30% ACD: 84% (p<0.001) No difference in VAS or ODI between groups Control: 16.6%
Control: 278 ACD: 8.8% (p<0.01) ACD: 7.1% (p=0.001)
ACD: 272
Bone resorption around the annular closure device during a postoperative followup of 8 years Sanginov et al. [61] 2024 Russia Barricaid Retrospective case series 133 85 5.30% 3.00% Not reported Bone resorption 63.6% of patients Significant improvement of VAS and ODI Not reported
Bone-anchored annular closure following lumbar discectomy reduces risk of complications and reoperations within 90 days of discharge Klassen et al. [24] 2017 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 3 Control: 6.8% Control: 5.4% Not reported Not reported Not reported Serious adverse event
Control: 278 ACD: 2.2% (p=0.01) ACD: 1.9% (p=0.03) Control: 16.3%
ACD: 272 ACD: 9.7% (p=0.056)
Device- or procedure-related
Control: 10.2%
ACD: 4.5% (p=0.02)
Cost savings associated with prevention of recurrent lumbar disc herniation with a novel annular closure device: a multicenter prospective cohort study Parker et al. [62] 2013 Croatia Barricaid Prospective case series 76 24 Control: 6.5% Not reported Not reported Not reported Not reported Not reported
Control: 46 ACD: 0.0% (p=0.27)
ACD: 30
Efficacy of a Novel Annular Closure Device after Lumbar Discectomy in Korean Patients: A 24-Month Follow-up of a Randomized Controlled Trial Cho et al. [63] 2019 Korea Barricaid RCT 60 24 Control: 20% Not reported Postoperative disc height Not reported No difference in VAS or ODI between groups 0%
Control: 30 ACD: 3.3% (p=0.044) Control: 10.2 ± 1.2 mm
ACD: 30 ACD: 11.4 ± 1.5 mm (p=0.006)
The high-risk discectomy patient: prevention of reherniation in patients with large anular defects using an anular closure device Bouma et al. [64] 2013 Germany and Croatia Barricaid Prospective case series 75 24 6.50% 1.40% Not reported Not reported Significant improvement of VAS and ODI Not reported
Three-year results from a randomized trial of lumbar discectomy with annulus fibrosus occlusion in patients at high risk for reherniation Kienzler et al. [25] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 36 Control: 29.5% Control: 19.3% Control: 6.4 ± 2.2 mm Control: 41% VAS and ODI significantly better in ACD group Control: 18.7%
Control: 278 ACD: 14.8% (p<0.001) ACD: 11.0% (p=0.007) ACD: 6.3 ± 2.2 mm (p=0.64) ACD: 89% (p<0.001) ACD: 10.7% (p=0.008)
ACD: 272
Surgical experience and complications in 50 patients treated with an anular closure device following lumbar discectomy Ardeshiri et al. [65] 2019 Germany Barricaid Prospective case series 50 12 2% 4% Not reported Not reported Significant improvement of VAS and ODI 4%
Endplate changes after lumbar discectomy with and without implantation of an annular closure device Barth et al. [26] 2018 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Prospective case series 493 12 Not reported Not reported Not reported Superior endplate VAS leg significantly better in ACD group. No difference in other measures Not reported
Control: 251 Control: 31.4%
ACD: 242 ACD: 71.6% (p<0.001)
Inferior endplate
Control: 11.1%
ACD: 56.1% (p<0.001)
Morphology and Clinical Relevance of Vertebral Endplate Changes Following Limited Lumbar Discectomy With or Without Bone-anchored Annular Closure Kuršumović et al. [27] 2018 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid RCT 550 24 Control: 24.0% Control: 13% Not reported Control: 33% No difference in VAS or ODI between groups Higher in control group with vertebral endplate changes compared to ACD group
Control: 283 ACD: 11% (p<0.001) ACD: 5% (p<0.001) ACD: 85%
ACD: 267
Performance of an Annular Closure Device in a ‘Real-World’, Heterogeneous, At-Risk, Lumbar Discectomy Population Kuršumović and Rath. [66] 2017 Germany Barricaid Retrospective case series 171 15 3.50% 7.00% Not reported 14% Significant improvement of ODI and VAS 8.8% of patients had ACD’s mesh detach
Post-lumbar discectomy reoperations that are associated with poor clinical and socioeconomic outcomes can be reduced through use of a novel annular closure device: results from a 2-year randomized controlled trial Klassen et al. [28] 2018 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Control: 25% Control: 16% Not reported Not reported Reoperations led to significantly worse VAS and ODI (p<0.001). Control: 1.1%
Control: 278 ACD: 12% ACD: 9% (p=0.01) ACD: 1.5%
ACD: 272 No difference between groups
Primary Limited Lumbar Discectomy with an Annulus Closure Device: One-Year Clinical and Radiographic Results from a Prospective, Multi-Center Study Lequin et al. [67] 2012 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Prospective case series 45 12 2.40% 2.40% Postoperative disc height: 92.8 ± 7.9% of baseline (p<0.01) Not reported Significant improvement of VAS and ODI 0%
Protecting facet joints post-lumbar discectomy: Barricaid annular closure device reduces risk of facet degeneration Trummer et al. [81] 2013 Germany and Austria Barricaid Prospective 212 12 Not reported Not reported Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 137
ACD: 75
Effect of an Annular Closure Device (Barricaid) on Same-Level Recurrent Disk Herniation and Disk Height Loss After Primary Lumbar Discectomy Two-year Results of a Multicenter Prospective Cohort Study Parker et al. [68] 2016 Croatia Barricaid Prospective case series 76 24 Control: 6.5% Control: 4.3% Postoperative disc height Not reported VAS leg Control: 2.2%
Control: 46 ACD: 0% (p=0.27) ACD: 0% Control: 6.9 ± 1.1 mm Control: 18 ± 18 ACD: 3.3%
ACD: 30 ACD: 7.63 ± 1.5 mm (p=0.054) ACD: 9 ± 20 (p<0.05)
VAS back
Control: 21 ± 22
ACD: 10 ± 19 (p<0.05)
ODI
Control: 21 ± 17
ACD: 11 ± 10 (p<0.05)
Effect of Anular Closure on Disk Height Maintenance and Reoperated Recurrent Herniation Following Lumbar Diskectomy: Two-Year Data Ledic et al. [80] 2015 Croatia, Germany, Netherlands Barricaid Prospective case series 75 24 1.5% 4.00% 92% of patients maintained at least 75% of preoperative disc height Not reported Significant improvement of VAS and ODI 2.70%
Implantation of a bone-anchored annular closure device in conjunction with tubular minimally invasive discectomy for lumbar disc herniation: a retrospective study Martens et al. [69] 2018 Belgium Barricaid Retrospective case series 60 24 3% 5% Not reported Not reported Not reported 0%
Occurrence of discal and non-discal changes after sequestrectomy alone versus sequestrectomy and implantation of an anulus closure device Barth et al. [70] 2016 Germany Barricaid Retrospective case series 85 18 Control: 50% Control: 12.5% Not reported Control: 10.3% No difference in VAS or ODI between groups Not reported
Control: 40 ACD: 4.9% (p<0.001) ACD: 2.2% (p=0.729) ACD: 52.4% (p<0.001)
ACD: 45
Two year real world results of lumbar discectomy with bone anchored annular closure in patients at high risk of reherniation Ardeshiri et al. [71] 2019 Germany Barricaid Prospective case series 75 24 1.40% 4% Not reported Not reported Significant improvement in VAS and ODI 0%
Use of Annular Closure Device (Barricaid®) for Preventing Lumbar Disc Reherniation: One-Year Results of Three Cases Hahn et al. [72] 2014 Korea Barricaid Retrospective case series 3 12 0% 0% Well maintained (no disc height loss at 1 yr) Not reported Significant improvement in VAS Not reported
Effectiveness of an Annular Closure Device to Prevent Recurrent Lumbar Disc Herniation A Secondary Analysis With 5 Years of Follow-up Thomé et al. [11] 2021 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 60 Control: 31.6% Control: 22.6% Disc height loss Control: 1.4% No difference in VAS or ODI between groups Control: 20.5%
Control: 278 ACD: 18.8% (p<0.001) ACD: 16.0% (p=0.03) Control: 1.7 mm ACD: 20.2% (p<0.001) ACD: 12.0% (p=0.008)
ACD: 272 ACD: 1.9 mm (p=0.31)
Lumbar Discectomy With Bone-Anchored Annular Closure Device in Patients With Large Annular Defects: One-Year Results Nunley et al. [73] 2023 United States Barricaid Prospective case series 55 12 3.70% 5.50% Not reported Not reported VAS and ODI Improved by at least minimal clinically important difference 5.0%
Lumbar discectomy with annulus fibrosus closure: A retrospective series of 53 consecutive patients Kurzbuch et al. [74] 2022 Switzerland Barricaid Retrospective case series 53 12 Control: 14.6% Control: 14.6% Not reported Not reported VAS and ODI improved by at least minimal clinically important difference Control: 0%
Control: 41 ACD: 8.3% ACD: 8.3% ACD: 0%
ACD: 12
Incidence and clinical impact of vertebral endplate changes after limited lumbar microdiscectomy and implantation of a bone-anchored annular closure device Kienzler et al. [29] 2021 Switzerland Barricaid Retrospective case series 72 14.67 24% 18% Disc height loss: 0.7 ± 0.6 mm 99% Significant improvement in VAS and ODI Device failure 26.4%
Intraoperative findings, complications, and short-term results after lumbar microdiscectomy with or without implantation of annular closure device Kienzler et al. [29] 2021 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 3 Control: 6.5% Control: 5% Not reported Not reported No significant difference in VAS and ODI between groups Serious adverse events Control: 7.9% ACD: 3.7%
Control: 278 ACD: 1.5% (p=0.004) ACD: 2.2%
ACD: 272
Risk factors for early reherniation after lumbar discectomy with or without annular closure: results of a multicenter randomized controlled study Kienzler et al. [30] 2021 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 3 Control: 6.5% Not reported Not reported Not reported No significant difference in VAS and ODI between groups Not reported
Control: 278 ACD: 1.5% (p=0.004)
ACD: 272
Clinical implications of vertebral endplate disruptions after lumbar discectomy: 3-year results from a randomized trial of a bone-anchored annular closure device Kuršumović et al. [31] 2020 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 36 Control: 29.5% Control: 19.3% Not reported Endplate disruption (n) Significantly improved VAS and ODI in ACD group No serious adverse events
Control: 278 ACD: 14.8% (p<0.001) ACD: 11.0% (p=0.007) Control: 140
ACD: 272 ACD: 436 (p<0.001)
Lumbar Discectomy With Barricaid Device Implantation in Patients at High Risk of Reherniation: Initial Results From a Postmarket Study Nunley et al. [76] 2021 United States Barricaid Prospective case series 55 3 3.60% 1.80% Not reported Not reported VAS improved 98% and ODI improved 95% by at least minimally clinically important difference 5.50%
Lumbar disc reherniation prevention with a bone-anchored annular closure device: 1-year results of a randomized trial van den Brink et al. [32] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 12 Control: 17.3% Control: 12.5% Not reported Not reported Not reported Control: 20.9%
Control: 278 ACD: 8.4% (p=0.002) ACD: 6.6% ACD: 11.2% (p=0.002)
ACD: 272
Reoperation After Primary Lumbar Discectomy with or without Implantation of a Bone-Anchored Annular Closure Device: Surgical Strategies and Clinical Outcomes Klassen et al. [33] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 46.8 Control: 29.5% Control: 19.3% Not reported Not reported Significantly improved VAS and ODI in ACD group Not reported
Control: 278 ACD: 14.8% (p<0.001) ACD: 11.0% (p=0.007)
ACD: 272
Annular closure device lowers reoperation risk 4 years after lumbar discectomy Nanda et al. [34] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 48 Not reported Control: 21.1% Not reported Not reported Significantly improved VAS and ODI in ACD group Not reported
Control: 278 ACD: 14.4% (p=0.03)
ACD: 272
Cost-effectiveness of a Bone-anchored Annular Closure Device Versus Conventional Lumbar Discectomy in Treating Lumbar Disc Herniations Ament et al. [35] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Not reported Not reported Not reported Not reported Not reported Not reported
Control: 278
ACD: 272
Clinical performance of a bone-anchored annular closure device in older adults Bouma et al. [36] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 36 Control: 21.1% Control: 26.3% Not reported Not reported Mean clinically important difference - VAS Control: 70.6% Not reported
Control: 278 ACD: 12.5% ACD: 11.1% ACD: 83.3% ODI
ACD: 272 Control: 70.6%
ACD: 84.6%
Reduction of direct costs in high-risk lumbar discectomy patients during the 90-day post-operative period through annular closure Thaci et al. [37] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 3 Control: 6.8% Control: 4.0% Not reported Not reported Not reported Control: 8.6%
Control: 278 ACD: 2.2% (p=0.01) ACD: 0.7% (p=0.02) ACD: 3.3% (p=0.01)
ACD: 272
Postoperative direct health care costs of lumbar discectomy are reduced with the use of a novel annular closure device in high-risk patients Ament et al. [38] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Control: 13% Control: 21.9% Not reported Not reported Not reported Control: 8 events
Control: 278 ACD: 25% (p<0.001) ACD: 10.7% ACD: 1 event
ACD: 272
Effectiveness of an annular closure device in a “real-world” population: stratification of registry data using screening criteria from a randomized controlled trial Kuršumović and Rath. [77] 2018 Germany Barricaid Retrospective case series 164 15.6 6.8% 6.8% Disc Height Not reported Significant improvement of VAS and ODI 9.10%
Loss: 0.38 ± 0.69 mm
Predictors of Treatment Success Following Limited Discectomy With Annular Closure for Lumbar Disc Herniation Krutko et al. [78] 2020 Russia Barricaid Retrospective case series 133 12 1.50% 3.00% Preoperative: 0.28 ± 0.05 mm End plate resorption increased significantly Significant improvement in VAS and ODI Not reported
Postoperative: 0.24 ± 0.05 mm (p<0.001)
Does Patient Blinding Influence Clinical Outcomes After Annular Closure Device Implantation? A Propensity Score-Matched Analysis Bouma et al. [39] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Blinded: 5.7% Blinded: 8.6% Not reported Not reported No difference in VAS and ODI between groups Blinded: 5.7%
Control: 278 Unblinded: 9.1% (p=0.59) Unblinded: 12.2% (p=0.19) Unblinded: 8.9% (p=0.63)
ACD: 272
Clinical outcomes in patients after lumbar disk surgery with annular reinforcement device: Two-year follow up Vukas et al. [79] 2013 Croatia Barricaid Prospective case series 102 24 Control: 6.9% Control: 6.9% Not reported Not reported Significant improvement in VAS and ODI Durotomy (n)
Control: 72 ACD: 0% ACD: 0% Control: 1
ACD: 30 ACD: 1
Challenges in the Analysis of Longitudinal Pain Data: Practical Lessons from a Randomized Trial of Annular Closure in Lumbar Disc Surgery Bouma et al. [40] 2019 Germany, Switzerland, Austria, Belgium, Netherlands, and France Barricaid Multicenter RCT 550 24 Control: 21.9% Not reported Not reported Not reported No difference in VAS between cohorts in unadjusted analysis. In integrated analysis, VAS significant improved in ACD group Not reported
Control: 278 ACD: 10.3% (p<0.001)
ACD: 272
Title Study Country Technique Design Sample (N)* Follow-up (mo) Reherniation rate Reoperation rate Disc height Endplate changes Functional outcomes Complications
Prospective, Multicenter, Randomized, Controlled Study of Anular Repair in Lumbar Discectomy Bailey et al. [21] 2013 United states Preloaded: Xclose Multicenter RCT 700 24 Not reported Control: 11.2% Not reported Not reported No difference in VAS and ODI between groups Control: 20.5%
Control: 250 Xclose: 9.7% (p=0.562) Suture: 17.6% p=0.34
Xclose: 500
Needle-Guided Suture Technique for Lumbar Annular Fiber Closure in Microendoscopic Discectomy: A Technical Note and Case Series Luo et al. [42] 2020 China Manual: needle-guided annular closure suture Retrospective case series 25 12 0% 0% Mean decrease in disc height (%) 8.11 ± 3.36 Not reported Significant improvement in VAS and ODI 4%
Study on the clinical effect of percutaneous transforaminal endoscopic discectomy combined with annulus fibrosus repair in the treatment of single-segment lumbar disc herniation in young and middle-aged patients Zhao et al. [43] 2024 China Preloaded: disposable annulus fibrosus stapler Retrospective case series 96 12 Control: 14% Not reported Not reported Not reported VAS and ODI significantly improved in suture groups Not reported
Control: 50 Suture: 2.2% (p<0.05)
Suture: 46
Full-endoscopic posterior longitudinal ligament coverage suturing for lumbar disc herniation with annular defects Zhang et al. [44] 2025 China Preloaded: disposable annulus fibrosus suture device Retrospective case series 56 14.3 Control: 17.6% Control: 2.9% Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 34 Suture: 0% (p<0.05) Suture: 0%
Suture: 22
The clinical application of “jetting suture” technique in annular repair under microendoscopic discectomy Qi et al. [45] 2016 China Manual: “Jetting” annular suture under MED Prospective case series 30 26.7 0% Not reported Not reported Not reported Significant improvement in ODI 0%
Repair Using Conventional Implant for Ruptured Annulus Fibrosus after Lumbar Discectomy: Surgical Technique and Case Series Suh et al. [46] 2015 Korea Bone-anchored: No. 2 fiberwire sutures and PushLock implants Retrospective case series 19 36 0% Not reported 2.4 ± 1.3mm (p= 0.08) change in preoperative vs. postoperative Not reported Significant improvement in VAS and ODI 0%
Uni-portal non-coaxial spinal endoscopic surgery combined with annulus fibrosus suture technique for lumbar disc herniation: Case series Li et al. [47] 2025 China Manual: endoscopic suturing Retrospective case series 22 11.3 0% 0% Preoperative Not reported Significant improvement in VAS and ODI Not reported
Control: 9.8 ± 1.5 mm
Suture: 9.5 ± 1.5 mm (p<0.0001)
Clinical effect of full endoscopic lumbar annulus fibrosus suture Peng et al. [48] 2024 China Manual: Endoscopic needle-guided annular suture Retrospective case series 72 12 Control: 12.2% Control: 7.3% Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 41 Suture: 0% (p=0.044) Suture: 0% (p=0.124)
Suture: 31
Bone anchoring annular suture technique for repairing annular defects at vertebral body edge following lumbar discectomy Wang et al. [49] 2025 China Bone-anchored: suture Retrospective case series 84 12.6 1.2% 0% Preop: 9.10 ± 0.75 mm Not reported Significant improvement in VAS and ODI 8.3%
Postop: 9.05 ± 0.82 mm (p=0.070)
Clinical efficacy of single-channel percutaneous endoscopic nucleotomy with annulus fibrosus suturing for lumbar disc herniation: A retrospective study Fu et al. [50] 2024 China Preloaded: STAR-S Suturing System Retrospective 86 12 Control: 9.52% Control: 9.52% Disc height loss rate Not reported No difference in VAS and ODI between groups 0%
Control: 42 Suture: 2.27% (p=0.029) Suture: 2.27% Control: 29.8%
Suture: 44 Suture: 22.3% (p<0.01)
A suture technique combining annulus fibrosis with posterior longitudinal ligament for lumbar disc herniation under endoscopy He et al. [51] 2025 China Preloaded: Disposable Annulus fibrosus Stapler Retrospective case control 412 15.2 Control: 9.3% Control: 3.4% Not reported Not reported VAS and ODI significantly improved in suture groups 0%
Control: 204 Suture: 3.8% (p=0.019) Suture: 0.5% (p=0.03)
Suture: 208
The effcet of annulus fibrosus suture combined with percutaneous transforaminal endoscopic discectomy on obese patients with lumbar disc herniation Zhao et al. [52] 2025 China Preloaded: Disposable Annulus fibrosus Stapler Retrospective 23 12 0% 0% Not reported Not reported Significant improvement of VAS and ODI 0%
Analysis of the clinical efficacy of visualization of percutaneous endoscopic lumbar discectomy combined with annulus fibrosus suture in lumbar disc herniation Xi et al. [53] 2024 China Preloaded: annulus fibrosus suture device Retrospective case control 106 12 Control: 9.59% Not reported Control Preop: 0.76 ± 0.19 mm Not reported No difference in VAS and ODI between groups Not reported
Control: 73 Suture: 3.03% (p=0.027) Postop: 0.67 ± 0.18 mm (p<0.001)
Suture: 33 Suture Preop: 0.86 ± 0.17 mm
Postop: 0.87 ± 0.08 mm (p=0.718)
A retrospective study of the midterm efficacy of full-endoscopic annulus fibrosus suture following lumbar discectomy Wang et al. [54] 2022 China Preloaded: annulus fibrosus suture device Retrospective case series 82 18 Control: 7.1% Control: 7.1% Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 42 Suture: 0% Suture: 0%
Suture: 40
Microendoscopic Discectomy Combined with Annular Suture Versus Percutaneous Transforaminal Endoscopic Discectomy for Lumbar Disc Herniation: A Prospective Observational Study Ren et al. [55] 2020 China Preloaded: annulus fibrosus suture device Prospective case series 135 36 Control: 12.7% Not reported Control: 11.2 ± 1.3 mm Not reported No difference in VAS and ODI between groups 0%
Control: 71 Suture: 6.3% (p=0.170) Suture: 12.0 ± 1.5 mm (p=0.007)
Suture: 64
A Pilot Study of Full-Endoscopic Annulus Fibrosus Suture Following Lumbar Discectomy: Technique Notes and One-Year Follow-Up Li et al. [56] 2020 China Preloaded: Disposable Annulus fibrosus Stapler Prospective case series 50 12 0% Not reported Not reported Not reported Significant improvement in VAS and ODI 0%
Clinical study of Microendoscopic Discectomy + Fibrous Ring Suture Versus Microendoscopic Discectomy alone in the treatment of lumbar disc herniation in young and middle-aged patients Cui et al. [57] 2024 China Manual: microendoscopic suturing Retrospective case series 66 12 Control: 9.1% Control: 9.1% Not reported Not reported No difference in VAS and ODI between groups 0%
Control: 33 Suture: 0% Suture: 0%
Suture: 33
Comparative outcomes of unilateral biportal endoscopic lumbar intervertebral discectomy with and without annulus fibrosus suture in lumbar disc herniation: a retrospective analysis Zhou et al. [58] 2025 China Preloaded: annulus fibrosus suture device Retrospective case series 177 24 Control: 3.6% Control: 5.1% Not reported Not reported No difference in VAS between groups Control: 1.4%
Control: 138 Suture: 0% (p<0.001) Suture: 2.6% Suture: 2.6%
Suture: 39
Title Study Country Technique/device Design Sample (N)* Follow-up (mo) Reherniation rate Reoperation rate Disc height maintenance Endplate changes Functional outcomes Complications
A novel full endoscopic annular repair technique combined with autologous conditioned plasma intradiscal injection: a new safe serial therapeutic model for the treatment of lumbar disc herniation Li et al. [59] 2021 China Disposable Annular Stapler/Autologous conditioned plasma Prospective case series 75 6 Control: 4.0% Not reported Not reported Not reported VAS back Not reported
Control: 25 Suture: 0% Control: 2.00 ± 0.18
Suture: 25 Suture+ACP: 0% Suture: 1.80 ± 0.12
Suture+ACP: 25 Suture+ACP: 0.96 ± 0.14 (p<0.001) VAS leg
Control: 1.96 ± 0.15
Suture: 1.68 ± 0.13
Suture+ACP: 1.48 ± 0.12 (p=0.038)
No difference in ODI
Fibrin sealants in lumbar annuloplasty after endoscopic discectomy as a method to prevent recurrent lumbar disc herniation Torkian et al. [22] 2020 Iran Fibrin sealant Prospective case series 35 10.5 Control: 5.5% Not reported Not reported Not reported VAS Control: 3 (2-5) Not reported
Control: 18 Fibrin: 11.7% Fibrin: 2 (2-4) (p=0.015)
Fibrin: 17
Selective Retention of Bone Marrow Stromal Cells with Gelatin Sponge for Repair of Intervertebral Disc Defects after Microendoscopic Discectomy: A Prospective Controlled Study and 2-year Follow-up Xu et al. [60] 2021 China Disposable Annular Stapler and Bone Marrow Stromal Cells and gelatin sponge Prospective case control 45 24 Control: 0% Not reported Disc height loss Not reported VAS improvement rate 0%
Control: 15 Suture: 0% Control: 29.3% ± 2.2% Control: 71.3% ± 7.0%
Suture: 15 Suture+BMSC: 0% Suture: 27.6% ± 0.7% Suture: 70.1% ± 7.8%
Suture+BMSC: 15 Suture+BMSC: 17.2% ± 1.3% (p<0.05) VAS Suture+BMSC: 80.1 ± 7.6% (p<0.05) ODI improvement rate
Control: 57.8% ± 8.1%
Suture: 59.9% ± 5.5%
Suture+BMSC: 65.6% ± 8.8% (p<0.05)
Table 1. Implantable physical device studies

VAS, visual analogue scale; ODI, Oswestry Disability Index; RCT, randomized controlled trial; ACD, anterior cervical discectomy.

Total number of patients included in the study.

Table 2. Suturing technique studies

VAS, visual analogue scale; ODI, Oswestry Disability Index; RCT, randomized controlled trial.

Total number of patients included in the study.

Table 3. Biomaterial studies

VAS, visual analogue scale; ACP, autologous conditioned plasma; BMSC, bone marrow stromal cell.

Total number of patients included in the study.

Table 1.

Table 2.

Table 3.

NS : Neurospine
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